WorldWideScience

Sample records for analysis structural evolution

  1. Analysis of ribosomal protein gene structures: implications for intron evolution.

    Directory of Open Access Journals (Sweden)

    2006-03-01

    Full Text Available Many spliceosomal introns exist in the eukaryotic nuclear genome. Despite much research, the evolution of spliceosomal introns remains poorly understood. In this paper, we tried to gain insights into intron evolution from a novel perspective by comparing the gene structures of cytoplasmic ribosomal proteins (CRPs and mitochondrial ribosomal proteins (MRPs, which are held to be of archaeal and bacterial origin, respectively. We analyzed 25 homologous pairs of CRP and MRP genes that together had a total of 527 intron positions. We found that all 12 of the intron positions shared by CRP and MRP genes resulted from parallel intron gains and none could be considered to be "conserved," i.e., descendants of the same ancestor. This was supported further by the high frequency of proto-splice sites at these shared positions; proto-splice sites are proposed to be sites for intron insertion. Although we could not definitively disprove that spliceosomal introns were already present in the last universal common ancestor, our results lend more support to the idea that introns were gained late. At least, our results show that MRP genes were intronless at the time of endosymbiosis. The parallel intron gains between CRP and MRP genes accounted for 2.3% of total intron positions, which should provide a reliable estimate for future inferences of intron evolution.

  2. An Analysis of the Structure and Evolution of Networks

    Science.gov (United States)

    Hua, Guangying

    2011-01-01

    As network research receives more and more attention from both academic researchers and practitioners, network analysis has become a fast growing field attracting many researchers from diverse fields such as physics, computer science, and sociology. This dissertation provides a review of theory and research on different real data sets from the…

  3. Brain structure evolution in a basal vertebrate clade: evidence from phylogenetic comparative analysis of cichlid fishes

    Directory of Open Access Journals (Sweden)

    Kolm Niclas

    2009-09-01

    Full Text Available Abstract Background The vertebrate brain is composed of several interconnected, functionally distinct structures and much debate has surrounded the basic question of how these structures evolve. On the one hand, according to the 'mosaic evolution hypothesis', because of the elevated metabolic cost of brain tissue, selection is expected to target specific structures mediating the cognitive abilities which are being favored. On the other hand, the 'concerted evolution hypothesis' argues that developmental constraints limit such mosaic evolution and instead the size of the entire brain varies in response to selection on any of its constituent parts. To date, analyses of these hypotheses of brain evolution have been limited to mammals and birds; excluding Actinopterygii, the basal and most diverse class of vertebrates. Using a combination of recently developed phylogenetic multivariate allometry analyses and comparative methods that can identify distinct rates of evolution, even in highly correlated traits, we studied brain structure evolution in a highly variable clade of ray-finned fishes; the Tanganyikan cichlids. Results Total brain size explained 86% of the variance in brain structure volume in cichlids, a lower proportion than what has previously been reported for mammals. Brain structures showed variation in pair-wise allometry suggesting some degree of independence in evolutionary changes in size. This result is supported by variation among structures on the strength of their loadings on the principal size axis of the allometric analysis. The rate of evolution analyses generally supported the results of the multivariate allometry analyses, showing variation among several structures in their evolutionary patterns. The olfactory bulbs and hypothalamus were found to evolve faster than other structures while the dorsal medulla presented the slowest evolutionary rate. Conclusion Our results favor a mosaic model of brain evolution, as certain

  4. Evolution of energy structures

    International Nuclear Information System (INIS)

    Because of the big inertia and long time constants of energy systems, their long-time behaviour is mainly determined by their present day state and by the trends of their recent evolution. For this reason, it is of prime importance to foresee the evolution of the different energy production sources which may play an important role in the future. A status of the world energy consumption and production is made first using the energy statistics of the IEA. Then, using the trends observed since 1973, the consequences of a simple extrapolation of these trends is examined. Finally, the scenarios of forecasting of energy structures, like those supplied by the International institute for applied systems analysis (IIASA) are discussed. (J.S.)

  5. Analysis on the Evolution of Agricultural Structure about Pan-Yangtze River Delta

    Institute of Scientific and Technical Information of China (English)

    DAI Jiang; LIU Zhi-ying

    2010-01-01

    Starting from the definition of agricultural structure,this paper firstly analyzes the change of industrial and spatial structure of agriculture of Pan-Yangtze River Delta,then inspects the relationship between the development of economics and the evolution of agricultural structure,an the end it provides policy recommendation about the development and adjustment of agricultural structure for the future.

  6. Structure and evolution of a European Parliament via a network and correlation analysis

    CERN Document Server

    Puccio, Elena; Piilo, Jyrki; Tumminello, Michele

    2016-01-01

    We present a study of the network of relationships among elected members of the Finnish parliament, based on a quantitative analysis of initiative co-signatures, and its evolution over 16 years. To understand the structure of the parliament, we constructed a statistically validated network of members, based on the similarity between the patterns of initiatives they signed. We looked for communities within the network and characterized them in terms of members' attributes, such as electoral district and party. To gain insight on the nested structure of communities, we constructed a hierarchical tree of members from the correlation matrix. Afterwards, we studied parliament dynamics yearly, with a focus on correlations within and between parties, by also distinguishing between government and opposition. Finally, we investigated the role played by specific individuals, at a local level. In particular, whether they act as proponents who gather consensus, or as signers. Our results provide a quantitative background...

  7. Genre Analysis: Structural and Linguistic Evolution of the English-Medium Medical Research Article (1985-2004)

    Science.gov (United States)

    Li, Li-Juan; Ge, Guang-Chun

    2009-01-01

    This paper reports a corpus-based genre analysis of the structural and linguistic evolution of medical research articles (RAs) written in English. Towards that end, we analyzed the frequency of occurrence of the 11 moves identified by Nwogu (1997), of the three most frequently used verb tenses (simple past, simple present and present perfect) and…

  8. Structural Evolution of Colloidal Crystal Films in the Process of Melting Revealed by Bragg Peak Analysis

    NARCIS (Netherlands)

    Sulyanova, Elena A.; Shabalin, Anatoly; Zozulya, Alexey V.; Meijer, Janne-Mieke; Dzhigaev, Dmitry; Gorobtsov, Oleg; Kurta, Ruslan P.; Lazarev, Sergey; Lorenz, Ulf; Singer, Andrej; Yefanov, Oleksandr; Zaluzhnyy, Ivan; Besedin, Ilya; Sprung, Michael; Petukhov, A. V.; Vartanyants, Ivan A.

    2015-01-01

    In situ X-ray diffraction studies of structural evolution of colloidal crystal films formed by polystyrene spherical particles upon incremental heating are reported. The Bragg peak parameters, such as peak position, integrated intensity, and radial and azimuthal widths were analyzed as a function of

  9. Combined Visualization of Structural and Metric Information for Software Evolution Analysis

    NARCIS (Netherlands)

    Gonzalez, Antonio; Theron, Roberto; Telea, Alexandru; Garcia, Francisco J.

    2009-01-01

    This paper discusses a proposal for the visualization of software evolution, with a focus on combining insight on changes that affect software metrics at project and class level, the project structure, the class hierarchy and the viewing of source code correlated to indirect class coupling. The prop

  10. Structure Model of Urban Traffic System Evolution

    Institute of Scientific and Technical Information of China (English)

    JIANG Ke-jin; ZHANG Dian-ye

    2008-01-01

    A structure model of urban traffic system evolution is built based on the analysis of the factors influencing the system evolution and the hierarchy between the factors. Then the influencing degrees of the factors are quantificationally analyzed by DEMATE (decision making trial and evaluation laboratory). The analysis results indicate that the traffic mode structure which achieves the highest central degree is the dominant influencing factor of the urban traffic system evolution, and that economy development and the traffic poficy axe the second important factors that also affect the traffic mode structures. Furthermore, physical geography is a basic restriction to the urban traffic system evolution.

  11. Structural Evolution of Colloidal Crystal Films in the Process of Melting Revealed by Bragg Peak Analysis

    OpenAIRE

    Sulyanova, Elena; Shabalin, Anatoly; Yefanov, Oleksandr; Zaluzhnyy, Ivan; Besedin, Ilya; Sprung, Michael; Petukhov, Andrei; Vartaniants, Ivan; Zozulya, Alexey; Meijer, Janne-Mieke; Dzhigaev, Dmitry; Gorobtsov, Oleg; Kurta, Ruslan; Lazarev, Sergey; Lorenz, Ulf

    2015-01-01

    In situ X-ray diffraction studies of structural evolution of colloidal crystal films formed by polystyrene spherical particles upon incremental heating are reported. The Bragg peak parameters, such as peak position, integrated intensity, and radial and azimuthal widths were analyzed as a function of temperature. A quantitative study of colloidal crystal lattice distortions and mosaic spread as a function of temperature was carried out using Williamson–Hall plots based on mosaic block model. T...

  12. Stellar Structure and Evolution

    CERN Document Server

    Kippenhahn, Rudolf; Weiss, Achim

    2013-01-01

    This long-awaited second edition of the classical textbook on Stellar Structure and Evolution by Kippenhahn and Weigert is a thoroughly revised version of the original text. Taking into account modern observational constraints as well as additional physical effects such as mass loss and diffusion, Achim Weiss and Rudolf Kippenhahn have succeeded in bringing the book up to the state-of-the-art with respect to both the presentation of stellar physics and the presentation and interpretation of current sophisticated stellar models. The well-received and proven pedagogical approach of the first edition has been retained. The book provides a comprehensive treatment of the physics of the stellar interior and the underlying fundamental processes and parameters. The models developed to explain the stability, dynamics and evolution of the stars are presented and great care is taken to detail the various stages in a star’s life. Just as the first edition, which remained a standard work for more than 20 years after its...

  13. Evolution of energy structures; Evolution des structures energetiques

    Energy Technology Data Exchange (ETDEWEB)

    Nifenecker, H. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    2005-07-01

    Because of the big inertia and long time constants of energy systems, their long-time behaviour is mainly determined by their present day state and by the trends of their recent evolution. For this reason, it is of prime importance to foresee the evolution of the different energy production sources which may play an important role in the future. A status of the world energy consumption and production is made first using the energy statistics of the IEA. Then, using the trends observed since 1973, the consequences of a simple extrapolation of these trends is examined. Finally, the scenarios of forecasting of energy structures, like those supplied by the International institute for applied systems analysis (IIASA) are discussed. (J.S.)

  14. Nuclear Shell Structure Evolution Theory

    OpenAIRE

    Wang, Zhengda; Wang, Xiaobin; Zhang, Xiaodong; Wang, Xiaochun

    2012-01-01

    The Self-similar-structure shell model (SSM) comes from the evolution of the conventional shell model (SM) and keeps the energy level of SM single particle harmonic oscillation motion. In SM, single particle motion is the positive harmonic oscillation and in SSM, the single particle motion is the negative harmonic oscillation. In this paper a nuclear evolution equation (NEE) is proposed. NEE describes the nuclear evolution process from gas state to liquid state and reveals the relations among...

  15. Emergence, Analysis and Evolution of Structures Concepts and Strategies Across Disciplines

    CERN Document Server

    Lucas, Klaus

    2010-01-01

    The study of structures and structure generating processes is a common concern of all scientific and technical disciplines. The present volume presents an interdisciplinary investigation of the different methods of analysis and modelling which, while differing considerably in detail, usually have evolutionary adaption or development schemes at their core. The book naturally falls into three parts - a first part summarizing the transdisciplinary fundamentals, a second part discussing in detail case studies from various fields (production engineering, medicine, management, molecular biology, energy engineering, civil engineering, logistics, sociology, physics) and a shorter outlook on the transdisciplinary perspective.

  16. An Analysis of Local Power Structure of Thailand: Evolution and Implications

    Directory of Open Access Journals (Sweden)

    SATAPORN ROENGTAM

    2016-07-01

    Full Text Available This study presents the results of the investigation about the current characteristics, composition and relationship of actors in the ‘Power Structure of Thailand’. The concept on ‘Power Structure Analysis’ by William Dommhoff is used to construct the conceptual framework and data analysis. The findings are divided into three (3 issues. Firstly, characteristics of the power structure and actors can be divided into three (3 groups, in which all of them have to work together systematically. Secondly, in terms of composition, these groups can be positioned into three (3 rings of power structures: the inner, middle and outer rings. And thirdly, these groups play certain roles according to their relationship. The inner takes responsibility about creating and planning, the middle takes responsibility about command and control, and the outer take responsibility about actions. All of them will have to work together in order to create, use and maintain their power to continuously collect and protect their interests in the province.

  17. Metagenomic analysis of microbiota structure evolution in phytoremediation of a swine lagoon wastewater.

    Science.gov (United States)

    Ye, Jianfeng; Song, Zhaofeng; Wang, Liang; Zhu, Jun

    2016-11-01

    Pytoremediation was studied in this project to treat swine manure lagoon wastewater characteristic of high concentrations of organic carbon, ammonium (N) and phosphorus (P). The impacts of introducing exogenous microalgae Chlorella into the lagoon wastewater on the removal of major nutrients and the transformation of the native wastewater microbiota structure were explored under two phytoremediation modes (shake flask and CO2-air bubbling). The results showed that the inoculation of microalgae could significantly enhance N and P removal. Metagenomic analysis of the native microbiota composition in the wastewater affected by algae inoculation revealed that a substantial population of algicidal bacteria was developed in the shake flask system, while in the CO2-air bubbling system, a niche for more mutualistic bacteria was created, which benefited the maximal algal growth with the simultaneous optimal N and P removal. To our knowledge, this study presents, the first reported case of applying metagenomic approach to a phytoremediation system treating real swine lagoon wastewater. PMID:27518033

  18. Morphotectonic analysis, structural evolution/pattern of a contractional ridge: Giouchtas Mt., Central Crete, Greece

    Indian Academy of Sciences (India)

    Kokinou Eleni; Skilodimou Hariklia D; Bathrellos George D; Antonarakou Assimina; Kamberis Evangelos

    2015-04-01

    The Giouchtas Mountain is situated south of Heraklion, Central Crete. It is a N–S trending morphological asymmetric ridge with a steep western slope, whilst its eastern slope is characterized by a smoother relief, composed of Mesozoic limestone and Eocene–lower Oligocene flysch of the Gavrovo–Tripolis zone. The present study focusses on the structural pattern and development of Giouchtas Mountain. Morphotectonic analyses in combination with field mapping and tectonic analysis were performed for this purpose. GIS techniques were used for mapping the spatial distribution of the geological features on the topographic relief of the area. Geomorphic indices, used in the present study, are the mountain front sinuosity index (Smf) and the valley floor/width ratio index (Vf). Based on Smf and Vf values, it is implied that this area can be assigned to a tectonic class I, corresponding to higher tectonic activity. However, spatial variations of the tectonic activity along the segmented fronts point to a general trend of increasing activity towards the north and especially, northeast. The model of this possibly active structural feature corresponds to a compressional mechanism followed by an earliest Mid. Miocene to Holocene late-stage deformation related to extensional faulting.

  19. Metagenomic Analysis of the Indian Ocean Picocyanobacterial Community: Structure, Potential Function and Evolution.

    Directory of Open Access Journals (Sweden)

    Beatriz Díez

    Full Text Available Unicellular cyanobacteria are ubiquitous photoautotrophic microbes that contribute substantially to global primary production. Picocyanobacteria such as Synechococcus and Prochlorococcus depend on chlorophyll a-binding protein complexes to capture light energy. In addition, Synechococcus has accessory pigments organized into phycobilisomes, and Prochlorococcus contains chlorophyll b. Across a surface water transect spanning the sparsely studied tropical Indian Ocean, we examined Synechococcus and Prochlorococcus occurrence, taxonomy and habitat preference in an evolutionary context. Shotgun sequencing of size fractionated microbial communities from 0.1 μm to 20 μm and subsequent phylogenetic analysis indicated that cyanobacteria account for up to 15% of annotated reads, with the genera Prochlorococcus and Synechococcus comprising 90% of the cyanobacterial reads, even in the largest size fraction (3.0-20 mm. Phylogenetic analyses of cyanobacterial light-harvesting genes (chl-binding pcb/isiA, allophycocyanin (apcAB, phycocyanin (cpcAB and phycoerythin (cpeAB mostly identified picocyanobacteria clades comprised of overlapping sequences obtained from Indian Ocean, Atlantic and/or Pacific Oceans samples. Habitat reconstructions coupled with phylogenetic analysis of the Indian Ocean samples suggested that large Synechococcus-like ancestors in coastal waters expanded their ecological niche towards open oligotrophic waters in the Indian Ocean through lineage diversification and associated streamlining of genomes (e.g. loss of phycobilisomes and acquisition of Chl b; resulting in contemporary small celled Prochlorococcus. Comparative metagenomic analysis with picocyanobacteria populations in other oceans suggests that this evolutionary scenario may be globally important.

  20. Metagenomic Analysis of the Indian Ocean Picocyanobacterial Community: Structure, Potential Function and Evolution.

    Science.gov (United States)

    Díez, Beatriz; Nylander, Johan A A; Ininbergs, Karolina; Dupont, Christopher L; Allen, Andrew E; Yooseph, Shibu; Rusch, Douglas B; Bergman, Birgitta

    2016-01-01

    Unicellular cyanobacteria are ubiquitous photoautotrophic microbes that contribute substantially to global primary production. Picocyanobacteria such as Synechococcus and Prochlorococcus depend on chlorophyll a-binding protein complexes to capture light energy. In addition, Synechococcus has accessory pigments organized into phycobilisomes, and Prochlorococcus contains chlorophyll b. Across a surface water transect spanning the sparsely studied tropical Indian Ocean, we examined Synechococcus and Prochlorococcus occurrence, taxonomy and habitat preference in an evolutionary context. Shotgun sequencing of size fractionated microbial communities from 0.1 μm to 20 μm and subsequent phylogenetic analysis indicated that cyanobacteria account for up to 15% of annotated reads, with the genera Prochlorococcus and Synechococcus comprising 90% of the cyanobacterial reads, even in the largest size fraction (3.0-20 mm). Phylogenetic analyses of cyanobacterial light-harvesting genes (chl-binding pcb/isiA, allophycocyanin (apcAB), phycocyanin (cpcAB) and phycoerythin (cpeAB)) mostly identified picocyanobacteria clades comprised of overlapping sequences obtained from Indian Ocean, Atlantic and/or Pacific Oceans samples. Habitat reconstructions coupled with phylogenetic analysis of the Indian Ocean samples suggested that large Synechococcus-like ancestors in coastal waters expanded their ecological niche towards open oligotrophic waters in the Indian Ocean through lineage diversification and associated streamlining of genomes (e.g. loss of phycobilisomes and acquisition of Chl b); resulting in contemporary small celled Prochlorococcus. Comparative metagenomic analysis with picocyanobacteria populations in other oceans suggests that this evolutionary scenario may be globally important. PMID:27196065

  1. Microrheology: Structural evolution under static and dynamic conditions by simultaneously analysis of confocal microscopy and diffusing wave spectroscopy

    NARCIS (Netherlands)

    Nicolas, Y.; Paques, M.; Knaebel, A.; Steyer, A.; Munch, J.P.; Blijdenstein, T.B.J.; Aken, van G.A.

    2003-01-01

    An oscillatory shear configuration was developed to improve understanding of structural evolution during deformation. It combines an inverted confocal scanning laser microscope (CSLM) and a special sample holder that can apply to the sample specific deformation: oscillatory shear or steady strain. I

  2. Multidimensional operando analysis of macroscopic structure evolution in lithium sulfur cells by X-ray radiography.

    Science.gov (United States)

    Risse, S; Jafta, C J; Yang, Y; Kardjilov, N; Hilger, A; Manke, I; Ballauff, M

    2016-04-21

    Lithium sulfur cells are the most promising candidate for the post lithium-ion battery era. Their major drawback is rapid capacity fading attributed to the complex electrochemical processes during charge and discharge which are not known precisely. Here we present for the first time a multidimensional operando measurement by combining X-ray radiography with impedance spectroscopy while galvanostatically charging and discharging a lithium sulfur cell. The formation of macroscopic sulfur crystals at the end of charge can be seen directly by X-ray radiography. These crystals can be assigned to stable α-sulfur (rhombic) and metastable β-sulfur (monoclinic) by their characteristic crystal habit. These crystal structures with a length of more than 1 mm form and dissolve rapidly during cycling. Their appearance is accompanied by characteristic signals in impedance spectroscopy. Macroscopic crystals of Li2S cannot be observed in full agreement with earlier studies by operando X-ray diffraction. In addition, X-ray radiography reveals non-wetted areas on the carbon cathode. These regions grow during discharge and are reduced during charge. The area of these electrochemically inactive spots is inversely proportional to discharge capacity. PMID:27035926

  3. Structural evolution of the VMS-hosting Kristineberg area, Sweden – constraints from structural analysis and 3-D-modelling

    OpenAIRE

    Hübert, J.; García, M.; Juhlin, C.; M. Dehghannejad; Hermansson, T.; Bauer, T.; P. Skyttä; Weihed, P.

    2012-01-01

    Structural mapping and 3-D-modelling with constraints from magnetotelluric (MT) and reflection seismic investigations have been used to provide a geological synthesis of the geometrically complex Kristineberg area in the western part of the Palaeoproterozoic Skellefte district. The results indicate that, like the south-eastern parts of the Skellefte district, the area was subjected to SSE-NNW transpressional deformation at around 1.87 Ga. The contrasting structural geometries between the Kris...

  4. An analysis of the structure and evolution of the scientific collaboration network of computer intelligence in games

    Science.gov (United States)

    Lara-Cabrera, R.; Cotta, C.; Fernández-Leiva, A. J.

    2014-02-01

    Games constitute a research domain that is attracting the interest of scientists from numerous disciplines. This is particularly true from the perspective of computational intelligence. In order to examine the growing importance of this area in the gaming domain, we present an analysis of the scientific collaboration network of researchers working on computational intelligence in games (CIG). This network has been constructed from bibliographical data obtained from the Digital Bibliography & Library Project (DBLP). We have analyzed from a temporal perspective several properties of the CIG network at the macroscopic, mesoscopic and microscopic levels, studying the large-scale structure, the growth mechanics, and collaboration patterns among other features. Overall, computational intelligence in games exhibits similarities with other collaboration networks such as for example a log-normal degree distribution and sub-linear preferential attachment for new authors. It also has distinctive features, e.g. the number of papers co-authored is exponentially distributed, the internal preferential attachment (new collaborations among existing authors) is linear, and fidelity rates (measured as the relative preference for publishing with previous collaborators) grow super-linearly. The macroscopic and mesoscopic evolution of the network indicates the field is very active and vibrant, but it is still at an early developmental stage. We have also analyzed communities and central nodes and how these are reflected in research topics, thus identifying active research subareas.

  5. Structural evolution of the VMS-hosting Kristineberg area, Sweden – constraints from structural analysis and 3-D-modelling

    Directory of Open Access Journals (Sweden)

    J. Hübert

    2012-10-01

    Full Text Available Structural mapping and 3-D-modelling with constraints from magnetotelluric (MT and reflection seismic investigations have been used to provide a geological synthesis of the geometrically complex Kristineberg area in the western part of the Palaeoproterozoic Skellefte district. The results indicate that, like the south-eastern parts of the Skellefte district, the area was subjected to SSE-NNW transpressional deformation at around 1.87 Ga. The contrasting structural geometries between the Kristineberg and the central Skellefte district areas may be attributed to the termination and splaying of a major ESE-WNW-striking high-strain zone into several branches in the northern part of the Kristineberg area. The transpressional structural signature was preferentially developed within the southern of the two antiformal structures of the area, "the Southern antiform", which exposes the deepest cut through the crust and hosts all the economic volcanogenic massive sulphides (VMS deposits of the area. Partitioning of the SSE-NNW transpression into N–S and E–W components led to formation of a characteristic "flat-steep-flat" geometry defining a highly non-cylindrical hinge of for the Southern antiform. Recognition of the transpressional structural signatures including the "flat-steep-flat" geometry and the distinct pattern of sub-horizontal E–W trending to moderately SW-plunging mineral lineations in the deeper crustal parts of the Kristineberg area is of significance for VMS exploration in both near mine and regional scales. The 3-D-model illustrating the outcomes of this study is available as a 3-D-PDF document through the publication website.

  6. Evolution of the Northeast German Basin — inferences from a 3D structural model and subsidence analysis

    Science.gov (United States)

    Scheck, M.; Bayer, U.

    1999-11-01

    A 3D structural model of the Northeast German Basin was evaluated with special emphasis on its evolution as an intracontinental depression. The study includes investigations on subsidence history and structural setting of the basin. Thickness evolution and calculated tectonic subsidence volumes of Permian to Quaternary sediments in the Northeast German Basin indicate that the subsidence history was related to five stages of basin evolution which differ in their subsidence mechanisms. For the initial rift phase in the Late Carboniferous to Early Permian, a dominant thermal event and subordinate horizontal stresses were indicated by thickness variation evolution and by structural evidence. The main part of basin subsidence occurred in a NW-SE-oriented basin in the subsequent phase of thermal relaxation with maximum subsidence from Early Permian (Rotliegend) to Middle Triassic (Muschelkalk). From Middle Triassic the thermal subsidence pattern was superposed by further tectonic events. In the Middle Triassic regional extension led to a reconfiguration of the southern part of the basin, where new NNE-SSW-trending troughs (Rheinsberg and Gifhorn Troughs) developed. In the Jurassic the northwestern part of the basin was uplifted while in the south the Keuper subsiding areas continued to sink and NW-SE-trending depressions, related to salt margins, became important. Differentiation continued into Cretaceous times when regional compression caused uplift of the southeastern part of the basin and basin margins. A final subsidence phase occurred in the Cenozoic. This was accompanied by intensive salt movement. Recent basin configuration reflects the superposition of structural elements resulting from different evolution stages. The main structural characteristics of the basin are: (1) a vertical tectonic zonation in a pre-Zechstein succession, which lacks significant internal structures, and a strongly deformed post-Zechstein succession, which was decoupled due to the thick

  7. Protein Evolution within a Structural Space

    OpenAIRE

    Deeds, Eric J.; Dokholyan, Nikolay V.; Shakhnovich, Eugene I.

    2003-01-01

    Understanding of the evolutionary origins of protein structures represents a key component of the understanding of molecular evolution as a whole. Here we seek to elucidate how the features of an underlying protein structural “space” might impact protein structural evolution. We approach this question using lattice polymers as a completely characterized model of this space. We develop a measure of structural comparison of lattice structures that is analogous to the one used to understand stru...

  8. Analysis on the Filament Structure Evolution in Reset Transition of Cu/HfO2/Pt RRAM Device.

    Science.gov (United States)

    Zhang, Meiyun; Long, Shibing; Li, Yang; Liu, Qi; Lv, Hangbing; Miranda, Enrique; Suñé, Jordi; Liu, Ming

    2016-12-01

    The resistive switching (RS) process of resistive random access memory (RRAM) is dynamically correlated with the evolution process of conductive path or conductive filament (CF) during its breakdown (rupture) and recovery (reformation). In this study, a statistical evaluation method is developed to analyze the filament structure evolution process in the reset operation of Cu/HfO2/Pt RRAM device. This method is based on a specific functional relationship between the Weibull slopes of reset parameters' distributions and the CF resistance (R on). The CF of the Cu/HfO2/Pt device is demonstrated to be ruptured abruptly, and the CF structure of the device has completely degraded in the reset point. Since no intermediate states are generated in the abrupt reset process, it is quite favorable for the reliable and stable one-bit operation in RRAM device. Finally, on the basis of the cell-based analytical thermal dissolution model, a Monte Carlo (MC) simulation is implemented to further verify the experimental results. This work provides inspiration for RRAM reliability and performance design to put RRAM into practical application. PMID:27389343

  9. Analysis on the Filament Structure Evolution in Reset Transition of Cu/HfO2/Pt RRAM Device

    Science.gov (United States)

    Zhang, Meiyun; Long, Shibing; Li, Yang; Liu, Qi; Lv, Hangbing; Miranda, Enrique; Suñé, Jordi; Liu, Ming

    2016-05-01

    The resistive switching (RS) process of resistive random access memory (RRAM) is dynamically correlated with the evolution process of conductive path or conductive filament (CF) during its breakdown (rupture) and recovery (reformation). In this study, a statistical evaluation method is developed to analyze the filament structure evolution process in the reset operation of Cu/HfO2/Pt RRAM device. This method is based on a specific functional relationship between the Weibull slopes of reset parameters' distributions and the CF resistance ( R on). The CF of the Cu/HfO2/Pt device is demonstrated to be ruptured abruptly, and the CF structure of the device has completely degraded in the reset point. Since no intermediate states are generated in the abrupt reset process, it is quite favorable for the reliable and stable one-bit operation in RRAM device. Finally, on the basis of the cell-based analytical thermal dissolution model, a Monte Carlo (MC) simulation is implemented to further verify the experimental results. This work provides inspiration for RRAM reliability and performance design to put RRAM into practical application.

  10. Structural Evolution of Carbon During Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Adel F. Sarofim; Angelo Kandas

    1998-10-28

    The examination of the structural evolution of carbon during oxidation has proven to be of scientific interest. Early modeling work of fluidized bed combustion showed that most of the reactions of interest occurs iOn the micropores, and this work has concentrated on these pores. This work has concentrated on evolution of macroporosity and rnicroporosity of carbons during kinetic controlled oxidation using SAXS, C02 and TEM analysis. Simple studies of fluidized bed combustion of coal chars has shown that many of the events considered fragmentation events previously may in fact be "hidden" or nonaccessible porosity. This makes the study of the microporous combustion characteristics of carbon even more important. The generation of a combustion resistant grid, coupled with measurements of the SAXS and C02 surface areas, fractal analysis and TEM studies has confined that soot particles shrink during their oxidation, as previously suspected. However, this shrinkage results in an overall change in structure. This structure becomes, on a radial basis, much more ordered near the edges, while the center itself becomes transparent to the TEM beam, implying a total lack of structure in this region. Although complex, this carbon structure is probably burning as to keep the density of the soot particles nearly the same. The TEM techniques developed for examination of soots has also been applied to Spherocarb. The Spherocarb during oxidation also increases its ordering,. This ordering, by present theories, would imply that the reactivity would go. However, the reactivity goes up, implying that structure of carbon is secondary in importance to catalytic effects.

  11. Evolution in Stage-Structured Populations

    Science.gov (United States)

    Barfield, Michael; Holt, Robert D.; Gomulkiewicz, Richard

    2016-01-01

    For many organisms, stage is a better predictor of demographic rates than age. Yet no general theoretical framework exists for understanding or predicting evolution in stage-structured populations. Here, we provide a general modeling approach that can be used to predict evolution and demography of stage-structured populations. This advances our ability to understand evolution in stage-structured populations to a level previously available only for populations structured by age. We use this framework to provide the first rigorous proof that Lande’s theorem, which relates adaptive evolution to population growth, applies to stage-classified populations, assuming only normality and that evolution is slow relative to population dynamics. We extend this theorem to allow for different means or variances among stages. Our next major result is the formulation of Price’s theorem, a fundamental law of evolution, for stage-structured populations. In addition, we use data from Trillium grandiflorum to demonstrate how our models can be applied to a real-world population and thereby show their practical potential to generate accurate projections of evolutionary and population dynamics. Finally, we use our framework to compare rates of evolution in age- versus stage-structured populations, which shows how our methods can yield biological insights about evolution in stage-structured populations. PMID:21460563

  12. Microrheology: Structural evolution under static and dynamic conditions by simultaneous analysis of confocal microscopy and diffusing wave spectroscopy

    Science.gov (United States)

    Nicolas, Yves; Paques, Marcel; Knaebel, Alexandra; Steyer, Alain; Munch, Jean-Pierre; Blijdenstein, Theo B. J.; van Aken, George A.

    2003-08-01

    An oscillatory shear configuration was developed to improve understanding of structural evolution during deformation. It combines an inverted confocal scanning laser microscope (CSLM) and a special sample holder that can apply to the sample specific deformation: oscillatory shear or steady strain. In this configuration, a zero-velocity plane is created in the sample by moving two plates in opposite directions, thereby providing stable observation conditions of the structural behavior under deformation. The configuration also includes diffusion wave spectroscopy (DWS) to monitor the network properties via particle mobility under static and dynamic conditions. CSLM and DWS can be performed simultaneously and three-dimensional images can be obtained under static conditions. This configuration is mainly used to study mechanistic phenomena like particle interaction, aggregation, gelation and network disintegration, interactions at interfaces under static and dynamic conditions in semisolid food materials (desserts, dressings, sauces, dairy products) and in nonfood materials (mineral emulsions, etc.). Preliminary data obtained with this new oscillatory shear configuration are described that demonstrate their capabilities and the potential contribution to other areas of application also.

  13. Phylogeny and evolution of RNA structure.

    Science.gov (United States)

    Gesell, Tanja; Schuster, Peter

    2014-01-01

    Darwin's conviction that all living beings on Earth are related and the graph of relatedness is tree-shaped has been essentially confirmed by phylogenetic reconstruction first from morphology and later from data obtained by molecular sequencing. Limitations of the phylogenetic tree concept were recognized as more and more sequence information became available. The other path-breaking idea of Darwin, natural selection of fitter variants in populations, is cast into simple mathematical form and extended to mutation-selection dynamics. In this form the theory is directly applicable to RNA evolution in vitro and to virus evolution. Phylogeny and population dynamics of RNA provide complementary insights into evolution and the interplay between the two concepts will be pursued throughout this chapter. The two strategies for understanding evolution are ultimately related through the central paradigm of structural biology: sequence ⇒ structure ⇒ function. We elaborate on the state of the art in modeling both phylogeny and evolution of RNA driven by reproduction and mutation. Thereby the focus will be laid on models for phylogenetic sequence evolution as well as evolution and design of RNA structures with selected examples and notes on simulation methods. In the perspectives an attempt is made to combine molecular structure, population dynamics, and phylogeny in modeling evolution.

  14. Photometric analysis of the structure evolution on the Pb-19.4%Sn melt surface in the S-L temperature range

    Directory of Open Access Journals (Sweden)

    Lyakhovitskii M.M.

    2011-05-01

    Full Text Available The structure evolution of alloys in solidification range is considered as the first-order phase transformation from the solid state to the liquid one, which occurs by the mechanism of nucleation and growth of more symmetrical phase to less symmetrical crystalline phase. The kinetic regularities of this transformation are studied by the method of the photometric analysis of structure images (PHASI, which makes it possible to establish the temperature dependence of the relationship between the solid and liquid phases and their distribution on the melt surface. The PHASI method is based on the combined analysis of the brightness spectra of the visible light reflections from the sample surface and of the distribution of its scattering centers in different intensity intervals. The data on the structure evolution of the Sn+19.4%Pb alloy upon melting and solidification were considered in parallel with the measured spectra of sound signals. It was revealed that a distinct maximum is observed in the temperature dependence of radiation energy in the temperature range of phase transformation from the liquid into the solid state and hot crack formation occurs near the transition zone in the region of the contact of the ingot with the crucible.

  15. Industrial Structure Evolution and Economic Growth in Dingxi City Based on Shift-Share Method and Location Quotient Analysis

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    According to the statistical data in the years 2004-2008, both Shift-Share Analysis and Location Quotient Analysis are used to compare the economic development status of counties (districts) in Dingxi City in the years 2004 and 2008. Advantages and disadvantages of industrial structure and competitiveness are analyzed, as well as the impacts of existing industrial structure on economic growth. Development direction and development focus of primary, secondary and tertiary industries are found out. Countermeasures for accelerating the economic development of counties (districts) in Dingxi City are put forward, such as increasing the inputs in characteristic agriculture, promoting the development of primary industry, speeding up the construction of large and medium industrial enterprises, enhancing the development of secondary industry, strengthening comprehensive environmental improvement in tourist area, and actively developing tertiary industry.

  16. The structure and evolution of story networks.

    Science.gov (United States)

    Karsdorp, Folgert; van den Bosch, Antal

    2016-06-01

    With this study, we advance the understanding about the processes through which stories are retold. A collection of story retellings can be considered as a network of stories, in which links between stories represent pre-textual (or ancestral) relationships. This study provides a mechanistic understanding of the structure and evolution of such story networks: we construct a story network for a large diachronic collection of Dutch literary retellings of Red Riding Hood, and compare this network to one derived from a corpus of paper chain letters. In the analysis, we first provide empirical evidence that the formation of these story networks is subject to age-dependent selection processes with a strong lopsidedness towards shorter time-spans between stories and their pre-texts (i.e. 'young' story versions are preferred in producing new versions). Subsequently, we systematically compare these findings with and among predictions of various formal models of network growth to determine more precisely which kinds of attractiveness are also at play or might even be preferred as explicatory models. By carefully studying the structure and evolution of the two story networks, then, we show that existing stories are differentially preferred to function as a new version's pre-text given three types of attractiveness: (i) frequency-based and (ii) model-based attractiveness which (iii) decays in time. PMID:27429767

  17. The structure and evolution of story networks.

    Science.gov (United States)

    Karsdorp, Folgert; van den Bosch, Antal

    2016-06-01

    With this study, we advance the understanding about the processes through which stories are retold. A collection of story retellings can be considered as a network of stories, in which links between stories represent pre-textual (or ancestral) relationships. This study provides a mechanistic understanding of the structure and evolution of such story networks: we construct a story network for a large diachronic collection of Dutch literary retellings of Red Riding Hood, and compare this network to one derived from a corpus of paper chain letters. In the analysis, we first provide empirical evidence that the formation of these story networks is subject to age-dependent selection processes with a strong lopsidedness towards shorter time-spans between stories and their pre-texts (i.e. 'young' story versions are preferred in producing new versions). Subsequently, we systematically compare these findings with and among predictions of various formal models of network growth to determine more precisely which kinds of attractiveness are also at play or might even be preferred as explicatory models. By carefully studying the structure and evolution of the two story networks, then, we show that existing stories are differentially preferred to function as a new version's pre-text given three types of attractiveness: (i) frequency-based and (ii) model-based attractiveness which (iii) decays in time.

  18. Effectiveness of Land Use Structure Evolution to Industrial Structure Transformation

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Scarcity of land resources and transformation of industrial structure is a pair of contradictory elements.We derive the characteristics of land use structure and industrial structure transformation in Xining City using Transformation Coefficient(TC):first,in the period 1999-2000,the land use structure coefficient(θ1) declined by 79.55%,but the overall evolution trend is gentle;second,the transformation coefficient of industrial structure(θ2) tended to decline ceaselessly on the whole,a decrease of 36.09%(overall,the transformation coefficient of industrial structure is slightly greater than the land use structure coefficient);third,the inter-annual variation of the two experienced ups and downs(in the period 1999-2007,the inter-annual variation was great and in the period 2008-2010,the inter-annual variation tended to be gentle).On the basis of autocorrelation and co-integration model,we draw the following conclusions through analysis:first,the land use structure in Xining City plays a role in promoting industrial structure transformation;second,there is a long-term equilibrium relationship between the two.Finally,relevant policy recommendations are put forward for the industrial development in Xining City.

  19. Ductile and brittle structural evolution of the Laxemar-Simpevarp area: an independent analysis based on local and regional constraints

    Energy Technology Data Exchange (ETDEWEB)

    Viola, Giulio (Geological Survey of Norway, Trondheim (Norway))

    2008-10-15

    This report discusses the main aspects of the ductile and brittle deformational evolution of the Laxemar-Simpevarp area. Based on the interpretation of existing potential field geophysical data, it is suggested that the structural ductile grain of the region is controlled by large, c. EW trending shear zones with an overall sinistral strike-slip kinematics. The Oskarshamn Shear Zone (OSZ) and the Mederhult lineament are two examples of these shear zones and it is proposed that the ductile lineaments mapped in Laxemar-Simpevarp are genetically linked to shearing accommodated by these shear zones. The structural interpretation of the geophysical imagery of the Laxemar-Simpevarp regional model area and the available meso-scale structural information indicate that the Laxemar-Simpevarp study area can be interpreted as the analogue of a large-scale S/C' structural pattern. In detail, the Aespoe shear zone and other similarly oriented ductile shears represent C' shear bands that deform sinistrally the intervening EW lineaments (the S surfaces), which locally are significantly crenulated/folded in response to their asymptotic bending into the C' shears. This geometric and kinematic interpretation implies that, in contrast to existing reconstructions and models, EW- and not NE-trending shear zones become the main structural ductile feature of the region. Shear forces acting parallel to these main zones can successfully explain all the ductile structures described and reported from the area. The greatest compressive stress at the time of ductile shearing would trend NE-SW. The brittle deformation history of the region is complex and results from the multiple reactivation of fracture- and fault sets caused by the many orogenic episodes that affected the area during 1.5 Gyr of geological brittle evolution. Fault-slip data from outcrops and oriented drill cores were used to compute paleo-stress states. In the general absence of time markers that help constrain

  20. Large scale comparative codon-pair context analysis unveils general rules that fine-tune evolution of mRNA primary structure.

    Directory of Open Access Journals (Sweden)

    Gabriela Moura

    Full Text Available BACKGROUND: Codon usage and codon-pair context are important gene primary structure features that influence mRNA decoding fidelity. In order to identify general rules that shape codon-pair context and minimize mRNA decoding error, we have carried out a large scale comparative codon-pair context analysis of 119 fully sequenced genomes. METHODOLOGIES/PRINCIPAL FINDINGS: We have developed mathematical and software tools for large scale comparative codon-pair context analysis. These methodologies unveiled general and species specific codon-pair context rules that govern evolution of mRNAs in the 3 domains of life. We show that evolution of bacterial and archeal mRNA primary structure is mainly dependent on constraints imposed by the translational machinery, while in eukaryotes DNA methylation and tri-nucleotide repeats impose strong biases on codon-pair context. CONCLUSIONS: The data highlight fundamental differences between prokaryotic and eukaryotic mRNA decoding rules, which are partially independent of codon usage.

  1. MADS-box gene evolution - structure and transcription patterns

    DEFF Research Database (Denmark)

    Johansen, Bo; Pedersen, Louise Buchholt; Skipper, Martin;

    2002-01-01

    Mads-box genes, ABC model, Evolution, Phylogeny, Transcription patterns, Gene structure, Conserved motifs......Mads-box genes, ABC model, Evolution, Phylogeny, Transcription patterns, Gene structure, Conserved motifs...

  2. Structural Architecture and Evolution of Kumkuli Basin, North Tibet

    Institute of Scientific and Technical Information of China (English)

    He Bizhu; Xu Zhiqin; Jiao Cunli; Cui Junwen; Wang Shenglang; Wang Gonghuai; Li Zhaoyang; Qiu Zhuli

    2009-01-01

    Utilizing the new data of gravity, magnetic, and magnetotelluric survey, we analyzed the characteristics of the three geophysical attribute (gravity, magnetic, and resistivity) interfaces and the deep architecture and structure of Kumkuli basin. The research results can provide basic data for early basin structural study. From coupled basin and mountain system, analysis of the structure, and evolution of Knmknli basin, we found that there was zoning from north to south and from west to east. Kumkuli basin has three structural architecture layers including metamorphic crystallization basement, fold basement and sedimentary cover. Knmkuli basin can be divided into three structural units, two depressions, and one uplift. Structural evolution of the Kumkuli basin can be divided into five evolution stages, including Kumkuli microcontinent formed in Sinian-Ordovician, suture around Kumkuli basin formed in Eopaleozoic, retroarc foreland basin formed in Neopaleozoic, rejuvenated foreland hasin developed in Mesozoic, and strike slip and compression basin developed in Cenozoic.

  3. EVOLUTION OF APPROACHES TO DEFINITION AND STRUCTURIZATION OF INTELLECTUAL CAPITAL

    OpenAIRE

    V. Virchenko

    2012-01-01

    Article is devoted to analysis of peculiarities of evolution theoretical approaches to analysis of the nature of intellectual capital. The stages of development of the intellectual capital theory and approaches to it's structurization are investigated. Peculiarities of the intellectual capital are considered.

  4. Evolution of dinosaur epidermal structures.

    Science.gov (United States)

    Barrett, Paul M; Evans, David C; Campione, Nicolás E

    2015-06-01

    Spectacularly preserved non-avian dinosaurs with integumentary filaments/feathers have revolutionized dinosaur studies and fostered the suggestion that the dinosaur common ancestor possessed complex integumentary structures homologous to feathers. This hypothesis has major implications for interpreting dinosaur biology, but has not been tested rigorously. Using a comprehensive database of dinosaur skin traces, we apply maximum-likelihood methods to reconstruct the phylogenetic distribution of epidermal structures and interpret their evolutionary history. Most of these analyses find no compelling evidence for the appearance of protofeathers in the dinosaur common ancestor and scales are usually recovered as the plesiomorphic state, but results are sensitive to the outgroup condition in pterosaurs. Rare occurrences of ornithischian filamentous integument might represent independent acquisitions of novel epidermal structures that are not homologous with theropod feathers.

  5. Geodynamic evolution and mantle structure

    NARCIS (Netherlands)

    de Jonge, M.R.

    1995-01-01

    With the advent of plate tectonic theory a framework has become available in which many observed features of the structure of the Earth can be understood. The theory can explain the geological processes that have resulted in terranes as diverse as oceans, mid-oceanic ridges, mountain belts, and intr

  6. Cross-linked structure of network evolution

    Energy Technology Data Exchange (ETDEWEB)

    Bassett, Danielle S., E-mail: dsb@seas.upenn.edu [Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Physics, University of California, Santa Barbara, California 93106 (United States); Sage Center for the Study of the Mind, University of California, Santa Barbara, California 93106 (United States); Wymbs, Nicholas F.; Grafton, Scott T. [Department of Psychology and UCSB Brain Imaging Center, University of California, Santa Barbara, California 93106 (United States); Porter, Mason A. [Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom); CABDyN Complexity Centre, University of Oxford, Oxford, OX1 1HP (United Kingdom); Mucha, Peter J. [Carolina Center for Interdisciplinary Applied Mathematics, Department of Mathematics, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, North Carolina 27599 (United States)

    2014-03-15

    We study the temporal co-variation of network co-evolution via the cross-link structure of networks, for which we take advantage of the formalism of hypergraphs to map cross-link structures back to network nodes. We investigate two sets of temporal network data in detail. In a network of coupled nonlinear oscillators, hyperedges that consist of network edges with temporally co-varying weights uncover the driving co-evolution patterns of edge weight dynamics both within and between oscillator communities. In the human brain, networks that represent temporal changes in brain activity during learning exhibit early co-evolution that then settles down with practice. Subsequent decreases in hyperedge size are consistent with emergence of an autonomous subgraph whose dynamics no longer depends on other parts of the network. Our results on real and synthetic networks give a poignant demonstration of the ability of cross-link structure to uncover unexpected co-evolution attributes in both real and synthetic dynamical systems. This, in turn, illustrates the utility of analyzing cross-links for investigating the structure of temporal networks.

  7. Cosmic evolution of Quasar radio structure

    Science.gov (United States)

    Hutchings, J. B.; Neff, S. G.

    1991-01-01

    We discuss the results of a survey of Quasar radio structures over redshifts from 0.6 to 3.7. There are clear evolutionary trends in size and luminosity, which suggest that the duty cycle of individual Quasars has increased over cosmic time. This affects source count statistics and gives clues on the evolution of Quasar environments.

  8. Cross-linked structure of network evolution

    International Nuclear Information System (INIS)

    We study the temporal co-variation of network co-evolution via the cross-link structure of networks, for which we take advantage of the formalism of hypergraphs to map cross-link structures back to network nodes. We investigate two sets of temporal network data in detail. In a network of coupled nonlinear oscillators, hyperedges that consist of network edges with temporally co-varying weights uncover the driving co-evolution patterns of edge weight dynamics both within and between oscillator communities. In the human brain, networks that represent temporal changes in brain activity during learning exhibit early co-evolution that then settles down with practice. Subsequent decreases in hyperedge size are consistent with emergence of an autonomous subgraph whose dynamics no longer depends on other parts of the network. Our results on real and synthetic networks give a poignant demonstration of the ability of cross-link structure to uncover unexpected co-evolution attributes in both real and synthetic dynamical systems. This, in turn, illustrates the utility of analyzing cross-links for investigating the structure of temporal networks

  9. Shaping galaxy evolution with galaxy structure

    Science.gov (United States)

    Cheung, Edmond

    A fundamental pursuit of astronomy is to understand galaxy evolution. The enormous scales and complex physics involved in this endeavor guarantees a never-ending journey that has enamored both astronomers and laymen alike. But despite the difficulty of this task, astronomers have still attempted to further this goal. Among of these astronomers is Edwin Hubble. His work, which includes the famous Hubble sequence, has immeasurably influenced our understanding of galaxy evolution. In this thesis, we present three works that continues Hubble's line of study by using galaxy structure to learn about galaxy evolution. First, we examine the dependence of galaxy quiescence on inner galactic structure with the AEGIS/ DEEP2 survey at 0.5In this thesis, we present three works that continues Hubble's line of study by using galaxy structure to learn about galaxy evolution. First, we examine the dependence of galaxy quiescence on inner galactic structure with the AEGIS/ DEEP2 survey at 0.5Hubble at 0.2

  10. Dynamic Neighborhood Structures in Parallel Evolution Strategies

    OpenAIRE

    Mehnen, Jörn; Rudolph, Günter; Weinert, Klaus

    2001-01-01

    Parallelizing is a straightforward approach to reduce the total computation time of evolutionary algorithms. Finding an appropriate communication network within spatially structured populations for improving convergence speed and convergence probability is a difficult task. A new method that uses a dynamic communication scheme in an evolution strategy will be compared with conventional static and dynamic approaches. The communication structure is based on a socalled diffusion model approach. ...

  11. NUMERICAL SOLUTION OF SHORELINE EVOLUTION NEAR COASTAL STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    Cai Ze-wei; Song Xiao-gang; Ye Chun-yang

    2003-01-01

    Numerical analysis was made for shoreline evolution in the vicinity of coastal structures, including spur dike, detached breakwaters. The nonlinear partial differential equation was derived, and numerical solutions were obtained by the finite difference method. The numerical results show good agreement with previous analytical results.

  12. Molecular evolution of rDNA in early diverging Metazoa: First comparative analysis and phylogenetic application of complete SSU rRNA secondary structures in Porifera

    OpenAIRE

    Wörheide Gert; Erpenbeck Dirk; Voigt Oliver

    2008-01-01

    Abstract Background The cytoplasmic ribosomal small subunit (SSU, 18S) ribosomal RNA (rRNA) is the most frequently-used gene for molecular phylogenetic studies. However, information regarding its secondary structure is neglected in most phylogenetic analyses. Incorporation of this information is essential in order to apply specific rRNA evolutionary models to overcome the problem of co-evolution of paired sites, which violates the basic assumption of the independent evolution of sites made by...

  13. Abundance and Temperature Dependency of Protein-Protein Interaction Revealed by Interface Structure Analysis and Stability Evolution

    Science.gov (United States)

    He, Yi-Ming; Ma, Bin-Guang

    2016-05-01

    Protein complexes are major forms of protein-protein interactions and implement essential biological functions. The subunit interface in a protein complex is related to its thermostability. Though the roles of interface properties in thermal adaptation have been investigated for protein complexes, the relationship between the interface size and the expression level of the subunits remains unknown. In the present work, we studied this relationship and found a positive correlation in thermophiles rather than mesophiles. Moreover, we found that the protein interaction strength in complexes is not only temperature-dependent but also abundance-dependent. The underlying mechanism for the observed correlation was explored by simulating the evolution of protein interface stability, which highlights the avoidance of misinteraction. Our findings make more complete the picture of the mechanisms for protein complex thermal adaptation and provide new insights into the principles of protein-protein interactions.

  14. Leptin and leptin receptor: Analysis of a structure to function relationship in interaction and evolution from humans to fish

    OpenAIRE

    Prokop, JW; Duff, RJ; Ball, HC; Copeland, DL; Londraville, RL

    2012-01-01

    Leptin is a circulating protein which regulates dietary intake through binding the leptin receptor. Numerous labs have used known structures and mutagenesis to study this binding process in common animal models (human, mouse and rat). Understanding this binding process in other vertebrate species will allow for a better understanding of leptin and leptin receptor function. The binding site between leptin and leptin receptor is highly conserved in mammals as confirmed through sequence alignmen...

  15. Giant Planet Formation, Evolution, and Internal Structure

    CERN Document Server

    Helled, Ravit; Podolak, Morris; Boley, Aaron; Meru, Farzana; Nayakshin, Sergei; Fortney, Jonathan J; Mayer, Lucio; Alibert, Yann; Boss, Alan P

    2013-01-01

    The large number of detected giant exoplanets offers the opportunity to improve our understanding of the formation mechanism, evolution, and interior structure of gas giant planets. The two main models for giant planet formation are core accretion and disk instability. There are substantial differences between these formation models, including formation timescale, favorable formation location, ideal disk properties for planetary formation, early evolution, planetary composition, etc. First, we summarize the two models including their substantial differences, advantages, and disadvantages, and suggest how theoretical models should be connected to available (and future) data. We next summarize current knowledge of the internal structures of solar- and extrasolar- giant planets. Finally, we suggest the next steps to be taken in giant planet exploration.

  16. INVESTMENT STRUCTURE AND EVOLUTION IN THE CONTEXT OF ECONOMIC CRISIS

    Directory of Open Access Journals (Sweden)

    CODAU CIPRIAN-CRACIUN

    2011-12-01

    Full Text Available The scope of this article is the evolution analysis of net investment in Romania between economic growth and international economic crisis. The analysis captures both the evolution of net investment by structure elements (buildings, outfits, other investments and the structure and evolution of investments by sources of financing. Also there is an analysis of the foreign direct investment (FDI share in the total net investment and the impact of the economic crisis on this share. The article aims to identify the main factors for the evolution of investments in Romania before the financial crisis and determine how the financial crisis influenced the structure and volume of investments in the national economy. Most previous studies have focused either on a small part of the investments made in Romania (in most cases the FDI have been analyzed or on the period of economic expansion without capturing the evolution of investment during the economic crisis. Previous research has highlighted especially the FDI influence on macroeconomic indicators of high importance for the economy (unemployment rate, GDP growth rate, etc. with less focus on the factors influencing these investments and the close connection between the economic context (economy status and the volume of these investments. For the analysis of the investment evolution during the mentioned period statistical data was used that captured both the investment evolution trend and the changes occurred by the national economy stepping into recession amid the global financial crisis established. To get an overview of the situation it was considered a time internal that captured both the economic growth and the period after the onset of the economic crisis. Thereby information was obtained on the volume of net investment during 2000-2010, on foreign direct investment in the period 2003-2010 and their share in total net investment and also on the main sources of investment financing during the

  17. Molecular evolution of rDNA in early diverging Metazoa: First comparative analysis and phylogenetic application of complete SSU rRNA secondary structures in Porifera

    Directory of Open Access Journals (Sweden)

    Wörheide Gert

    2008-02-01

    Full Text Available Abstract Background The cytoplasmic ribosomal small subunit (SSU, 18S ribosomal RNA (rRNA is the most frequently-used gene for molecular phylogenetic studies. However, information regarding its secondary structure is neglected in most phylogenetic analyses. Incorporation of this information is essential in order to apply specific rRNA evolutionary models to overcome the problem of co-evolution of paired sites, which violates the basic assumption of the independent evolution of sites made by most phylogenetic methods. Information about secondary structure also supports the process of aligning rRNA sequences across taxa. Both aspects have been shown to increase the accuracy of phylogenetic reconstructions within various taxa. Here, we explore SSU rRNA secondary structures from the three extant classes of Phylum Porifera (Grant, 1836, a pivotal, but largely unresolved taxon of early branching Metazoa. This is the first phylogenetic study of poriferan SSU rRNA data to date that includes detailed comparative secondary structure information for all three sponge classes. Results We found base compositional and structural differences in SSU rRNA among Demospongiae, Hexactinellida (glass sponges and Calcarea (calcareous sponges. We showed that analyses of primary rRNA sequences, including secondary structure-specific evolutionary models, in combination with reconstruction of the evolution of unusual structural features, reveal a substantial amount of additional information. Of special note was the finding that the gene tree topologies of marine haplosclerid demosponges, which are inconsistent with the current morphology-based classification, are supported by our reconstructed evolution of secondary structure features. Therefore, these features can provide alternative support for sequence-based topologies and give insights into the evolution of the molecule itself. To encourage and facilitate the application of rRNA models in phylogenetics of early

  18. Macrodomains: Structure, Function, Evolution, and Catalytic Activities.

    Science.gov (United States)

    Rack, Johannes Gregor Matthias; Perina, Dragutin; Ahel, Ivan

    2016-06-01

    Recent developments indicate that macrodomains, an ancient and diverse protein domain family, are key players in the recognition, interpretation, and turnover of ADP-ribose (ADPr) signaling. Crucial to this is the ability of macrodomains to recognize ADPr either directly, in the form of a metabolic derivative, or as a modification covalently bound to proteins. Thus, macrodomains regulate a wide variety of cellular and organismal processes, including DNA damage repair, signal transduction, and immune response. Their importance is further indicated by the fact that dysregulation or mutation of a macrodomain is associated with several diseases, including cancer, developmental defects, and neurodegeneration. In this review, we summarize the current insights into macrodomain evolution and how this evolution influenced their structural and functional diversification. We highlight some aspects of macrodomain roles in pathobiology as well as their emerging potential as therapeutic targets. PMID:26844395

  19. Evolution of sensory structures in basal metazoa.

    Science.gov (United States)

    Jacobs, Dave K; Nakanishi, Nagayasu; Yuan, David; Camara, Anthony; Nichols, Scott A; Hartenstein, Volker

    2007-11-01

    Cnidaria have traditionally been viewed as the most basal animals with complex, organ-like multicellular structures dedicated to sensory perception. However, sponges also have a surprising range of the genes required for sensory and neural functions in Bilateria. Here, we: (1) discuss "sense organ" regulatory genes, including; sine oculis, Brain 3, and eyes absent, that are expressed in cnidarian sense organs; (2) assess the sensory features of the planula, polyp, and medusa life-history stages of Cnidaria; and (3) discuss physiological and molecular data that suggest sensory and "neural" processes in sponges. We then develop arguments explaining the shared aspects of developmental regulation across sense organs and between sense organs and other structures. We focus on explanations involving divergent evolution from a common ancestral condition. In Bilateria, distinct sense-organ types share components of developmental-gene regulation. These regulators are also present in basal metazoans, suggesting evolution of multiple bilaterian organs from fewer antecedent sensory structures in a metazoan ancestor. More broadly, we hypothesize that developmental genetic similarities between sense organs and appendages may reflect descent from closely associated structures, or a composite organ, in the common ancestor of Cnidaria and Bilateria, and we argue that such similarities between bilaterian sense organs and kidneys may derive from a multifunctional aggregations of choanocyte-like cells in a metazoan ancestor. We hope these speculative arguments presented here will stimulate further discussion of these and related questions. PMID:21669752

  20. Colloidal structural evolution of asphaltene studied by confocal microscopy

    Science.gov (United States)

    Hung, Jannett; Castillo, Jimmy A.; Reyes, A.

    2004-10-01

    In this work, a detail analysis of the flocculation kinetic of asphaltenes colloidal particles has been carried out usng confocal microscopy. The colloidal structural evolution of the asphaltene flocculated has had varies postulated; however, the aggregation process of asphaltene is still not fully understood. In a recent paper, using Confocal microscope (homemade), we reported high-resolution micrographic images of asphaltenes flocculated and the correlation between crude oil stability and flocculation process. This technique permitted visualizes directly the physical nature of asphaltene flocculated. In this work, a detail analysis of the flocculation kinetic of asphaltene colloidal particles has been carried out using confocal microscopy. The physical nature of asphaltene flocculated from different crude oils is showed through of high-resolution image micrographies and its colloidal structural evolution.

  1. Crystallography, evolution, and the structure of viruses.

    Science.gov (United States)

    Rossmann, Michael G

    2012-03-16

    My undergraduate education in mathematics and physics was a good grounding for graduate studies in crystallographic studies of small organic molecules. As a postdoctoral fellow in Minnesota, I learned how to program an early electronic computer for crystallographic calculations. I then joined Max Perutz, excited to use my skills in the determination of the first protein structures. The results were even more fascinating than the development of techniques and provided inspiration for starting my own laboratory at Purdue University. My first studies on dehydrogenases established the conservation of nucleotide-binding structures. Having thus established myself as an independent scientist, I could start on my most cherished ambition of studying the structure of viruses. About a decade later, my laboratory had produced the structure of a small RNA plant virus and then, in another six years, the first structure of a human common cold virus. Many more virus structures followed, but soon it became essential to supplement crystallography with electron microscopy to investigate viral assembly, viral infection of cells, and neutralization of viruses by antibodies. A major guide in all these studies was the discovery of evolution at the molecular level. The conservation of three-dimensional structure has been a recurring theme, from my experiences with Max Perutz in the study of hemoglobin to the recognition of the conserved nucleotide-binding fold and to the recognition of the jelly roll fold in the capsid protein of a large variety of viruses.

  2. Structural Analysis of Histo-Blood Group Antigen Binding Specificity in a Norovirus GII.4 Epidemic Variant: Implications for Epochal Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Shanker, Sreejesh; Choi, Jae-Mun; Sankaran, Banumathi; Atmar, Robert L.; Estes, Mary K.; Prasad, B.V. Venkataram (Baylor); (LBNL)

    2012-03-23

    Susceptibility to norovirus (NoV), a major pathogen of epidemic gastroenteritis, is associated with histo-blood group antigens (HBGAs), which are also cell attachment factors for this virus. GII.4 NoV strains are predominantly associated with worldwide NoV epidemics with a periodic emergence of new variants. The sequence variations in the surface-exposed P domain of the capsid protein resulting in differential HBGA binding patterns and antigenicity are suggested to drive GII.4 epochal evolution. To understand how temporal sequence variations affect the P domain structure and contribute to epochal evolution, we determined the P domain structure of a 2004 variant with ABH and secretor Lewis HBGAs and compared it with the previously determined structure of a 1996 variant. We show that temporal sequence variations do not affect the binding of monofucosyl ABH HBGAs but that they can modulate the binding strength of difucosyl Lewis HBGAs and thus could contribute to epochal evolution by the potentiated targeting of new variants to Lewis-positive, secretor-positive individuals. The temporal variations also result in significant differences in the electrostatic landscapes, likely reflecting antigenic variations. The proximity of some of these changes to the HBGA binding sites suggests the possibility of a coordinated interplay between antigenicity and HBGA binding in epochal evolution. From the observation that the regions involved in the formation of the HBGA binding sites can be conformationally flexible, we suggest a plausible mechanism for how norovirus disassociates from salivary mucin-linked HBGA before reassociating with HBGAs linked to intestinal epithelial cells during its passage through the gastrointestinal tract.

  3. Mathematical Analysis of Evolution, Information, and Complexity

    CERN Document Server

    Arendt, Wolfgang

    2009-01-01

    Mathematical Analysis of Evolution, Information, and Complexity deals with the analysis of evolution, information and complexity. The time evolution of systems or processes is a central question in science, this text covers a broad range of problems including diffusion processes, neuronal networks, quantum theory and cosmology. Bringing together a wide collection of research in mathematics, information theory, physics and other scientific and technical areas, this new title offers elementary and thus easily accessible introductions to the various fields of research addressed in the book.

  4. Triadic Conceptual Structure of the Maximum Entropy Approach to Evolution

    CERN Document Server

    Herrmann-Pillath, Carsten

    2010-01-01

    Many problems in evolutionary theory are cast in dyadic terms, such as the polar oppositions of organism and environment. We argue that a triadic conceptual structure offers an alternative perspective under which the information generating role of evolution as a physical process can be analyzed, and propose a new diagrammatic approach. Peirce's natural philosophy was deeply influenced by his reception of both Darwin's theory and thermodynamics. Thus, we elaborate on a new synthesis which puts together his theory of signs and modern Maximum Entropy approaches to evolution. Following recent contributions to the naturalization of Peircean semiosis, we show that triadic structures involve the conjunction of three different kinds of causality, efficient, formal and final. We apply this on Ulanowicz's analysis of autocatalytic cycles as primordial patterns of life. This paves the way for a semiotic view of thermodynamics which is built on the idea that Peircean interpretants are systems of physical inference device...

  5. Structural evolution and metallicity of lead clusters

    Science.gov (United States)

    Götz, Daniel A.; Shayeghi, Armin; Johnston, Roy L.; Schwerdtfeger, Peter; Schäfer, Rolf

    2016-05-01

    The evolution of the metallic state in lead clusters and its structural implications are subject to ongoing discussions. Here we present molecular beam electric deflection studies of neutral PbN (N = 19-25, 31, 36, 54) clusters. Many of them exhibit dipole moments or anomalies of the polarizability indicating a non-metallic state. In order to resolve their structures, the configurational space is searched using the Pool Birmingham Cluster Genetic algorithm based on density functional theory. Spin-orbit effects on the geometries and dipole moments are taken into account by further relaxing them with two-component density functional theory. Geometries and dielectric properties from quantum chemical calculations are then used to simulate beam deflection profiles. Structures are assigned by the comparison of measured and simulated beam profiles. Energy gaps are calculated using time-dependent density functional theory. They are compared to Kubo gaps, which are an indicator of the metallicity in finite particles. Both, experimental and theoretical data suggest that lead clusters are not metallic up to at least 36 atoms.The evolution of the metallic state in lead clusters and its structural implications are subject to ongoing discussions. Here we present molecular beam electric deflection studies of neutral PbN (N = 19-25, 31, 36, 54) clusters. Many of them exhibit dipole moments or anomalies of the polarizability indicating a non-metallic state. In order to resolve their structures, the configurational space is searched using the Pool Birmingham Cluster Genetic algorithm based on density functional theory. Spin-orbit effects on the geometries and dipole moments are taken into account by further relaxing them with two-component density functional theory. Geometries and dielectric properties from quantum chemical calculations are then used to simulate beam deflection profiles. Structures are assigned by the comparison of measured and simulated beam profiles. Energy gaps

  6. Structural evolution in the crystallization of rapid cooling silver melt

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Z.A., E-mail: ze.tian@gmail.com [School of Physics and Electronics, Hunan University, Changsha 410082 (China); Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Dong, K.J.; Yu, A.B. [Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2015-03-15

    The structural evolution in a rapid cooling process of silver melt has been investigated at different scales by adopting several analysis methods. The results testify Ostwald’s rule of stages and Frank conjecture upon icosahedron with many specific details. In particular, the cluster-scale analysis by a recent developed method called LSCA (the Largest Standard Cluster Analysis) clarified the complex structural evolution occurred in crystallization: different kinds of local clusters (such as ico-like (ico is the abbreviation of icosahedron), ico-bcc like (bcc, body-centred cubic), bcc, bcc-like structures) in turn have their maximal numbers as temperature decreases. And in a rather wide temperature range the icosahedral short-range order (ISRO) demonstrates a saturated stage (where the amount of ico-like structures keeps stable) that breeds metastable bcc clusters. As the precursor of crystallization, after reaching the maximal number bcc clusters finally decrease, resulting in the final solid being a mixture mainly composed of fcc/hcp (face-centred cubic and hexagonal-closed packed) clusters and to a less degree, bcc clusters. This detailed geometric picture for crystallization of liquid metal is believed to be useful to improve the fundamental understanding of liquid–solid phase transition. - Highlights: • A comprehensive structural analysis is conducted focusing on crystallization. • The involved atoms in our analysis are more than 90% for all samples concerned. • A series of distinct intermediate states are found in crystallization of silver melt. • A novelty icosahedron-saturated state breeds the metastable bcc state.

  7. Models of protocellular structures, functions and evolution

    Science.gov (United States)

    Pohorille, Andrew; New, Michael H.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The central step in the origin of life was the emergence of organized structures from organic molecules available on the early earth. These predecessors to modern cells, called 'proto-cells,' were simple, membrane bounded structures able to maintain themselves, grow, divide, and evolve. Since there is no fossil record of these earliest of life forms, it is a scientific challenge to discover plausible mechanisms for how these entities formed and functioned. To meet this challenge, it is essential to create laboratory models of protocells that capture the main attributes associated with living systems, while remaining consistent with known, or inferred, protobiological conditions. This report provides an overview of a project which has focused on protocellular metabolism and the coupling of metabolism to energy transduction. We have assumed that the emergence of systems endowed with genomes and capable of Darwinian evolution was preceded by a pre-genomic phase, in which protocells functioned and evolved using mostly proteins, without self-replicating nucleic acids such as RNA.

  8. The proteome: structure, function and evolution.

    Science.gov (United States)

    Fleming, Keiran; Kelley, Lawrence A; Islam, Suhail A; MacCallum, Robert M; Muller, Arne; Pazos, Florencio; Sternberg, Michael J E

    2006-03-29

    This paper reports two studies to model the inter-relationships between protein sequence, structure and function. First, an automated pipeline to provide a structural annotation of proteomes in the major genomes is described. The results are stored in a database at Imperial College, London (3D-GENOMICS) that can be accessed at www.sbg.bio.ic.ac.uk. Analysis of the assignments to structural superfamilies provides evolutionary insights. 3D-GENOMICS is being integrated with related proteome annotation data at University College London and the European Bioinformatics Institute in a project known as e-protein (http://www.e-protein.org/). The second topic is motivated by the developments in structural genomics projects in which the structure of a protein is determined prior to knowledge of its function. We have developed a new approach PHUNCTIONER that uses the gene ontology (GO) classification to supervise the extraction of the sequence signal responsible for protein function from a structure-based sequence alignment. Using GO we can obtain profiles for a range of specificities described in the ontology. In the region of low sequence similarity (around 15%), our method is more accurate than assignment from the closest structural homologue. The method is also able to identify the specific residues associated with the function of the protein family.

  9. Accelerated probabilistic inference of RNA structure evolution

    Directory of Open Access Journals (Sweden)

    Holmes Ian

    2005-03-01

    Full Text Available Abstract Background Pairwise stochastic context-free grammars (Pair SCFGs are powerful tools for evolutionary analysis of RNA, including simultaneous RNA sequence alignment and secondary structure prediction, but the associated algorithms are intensive in both CPU and memory usage. The same problem is faced by other RNA alignment-and-folding algorithms based on Sankoff's 1985 algorithm. It is therefore desirable to constrain such algorithms, by pre-processing the sequences and using this first pass to limit the range of structures and/or alignments that can be considered. Results We demonstrate how flexible classes of constraint can be imposed, greatly reducing the computational costs while maintaining a high quality of structural homology prediction. Any score-attributed context-free grammar (e.g. energy-based scoring schemes, or conditionally normalized Pair SCFGs is amenable to this treatment. It is now possible to combine independent structural and alignment constraints of unprecedented general flexibility in Pair SCFG alignment algorithms. We outline several applications to the bioinformatics of RNA sequence and structure, including Waterman-Eggert N-best alignments and progressive multiple alignment. We evaluate the performance of the algorithm on test examples from the RFAM database. Conclusion A program, Stemloc, that implements these algorithms for efficient RNA sequence alignment and structure prediction is available under the GNU General Public License.

  10. Connectivity of neutral networks and structural conservation in protein evolution

    OpenAIRE

    Bastolla, Ugo; Porto, Markus; Roman, H. Eduardo; Vendruscolo, Michele

    2001-01-01

    Protein structures are much more conserved than sequences during evolution. Based on this observation, we investigate the consequences of structural conservation on protein evolution. We study seven of the most studied protein folds, finding out that an extended neutral network in sequence space is associated to each of them. Within our model, neutral evolution leads to a non-Poissonian substitution process, due to the broad distribution of connectivities in neutral networks. The observation ...

  11. Models of Protocellular Structure, Function and Evolution

    Science.gov (United States)

    New, Michael H.; Pohorille, Andrew; Szostak, Jack W.; Keefe, Tony; Lanyi, Janos K.

    2001-01-01

    In the absence of any record of protocells, the most direct way to test our understanding of the origin of cellular life is to construct laboratory models that capture important features of protocellular systems. Such efforts are currently underway in a collaborative project between NASA-Ames, Harvard Medical School and University of California. They are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures. The centerpiece of this project is a method for the in vitro evolution of protein enzymes toward arbitrary catalytic targets. A similar approach has already been developed for nucleic acids in which a small number of functional molecules are selected from a large, random population of candidates. The selected molecules are next vastly multiplied using the polymerase chain reaction. A mutagenic approach, in which the sequences of selected molecules are randomly altered, can yield further improvements in performance or alterations of specificities. Unfortunately, the catalytic potential of nucleic acids is rather limited. Proteins are more catalytically capable but cannot be directly amplified. In the new technique, this problem is circumvented by covalently linking each protein of the initial, diverse, pool to the RNA sequence that codes for it. Then, selection is performed on the proteins, but the nucleic acids are replicated. Additional information is contained in the original extended abstract.

  12. Study on Evolution of Spatial Structure of Pan-Linxia Economic Zone

    OpenAIRE

    Jing Xu

    2014-01-01

    This paper applies spatial correlation method in spatial statistics and GIS technology to analyze special structural form and evolution process of regional economy of Pan-Linxia region. Morphological analysis of spatial structure shows the correlation between economic development level of Linxia City and regional economic development in the minority area of south Gansu has strong complementarities. The evolution of spatial structure shows spatial correlation between the economy in Linxia City...

  13. Magnetic field structure evolution in RMF plasmas

    Science.gov (United States)

    Petrov, Yuri; Yang, Xiaokang; Huang, Tian-Sen

    2007-11-01

    A study of magnetic field structure evolution during 40-ms plasma discharge had been performed in 80 cm long / 40 cm OD cylindrical chamber. Plasma current Ip˜2--3 kA is produced by applied 500 kHz rotating magnetic field. In experiments, the 2D profile of plasma current is changed by feeding a 10-ms pulse current to additional magnetic coil located at the midplane. Using newly developed magnetic field pick-up coils system, we scanned the magnetic field in cross-section of plasma. Two experimental regimes were studied: without external toroidal field (TF), and with TF produced by applied axial current. When a relatively small current (<0.5 kA) is applied to the midplane coil, in both cases the total plasma current measured with Rogowski coil experiences a jump (up to 100%), but the profile of current remains almost unchanged. When a larger current (1--2 kA) is applied to the midplane coil, the total plasma current drops; the magnetic structure changes differently in two regimes. In regime without TF, the magnetic field of plasma current is reversed at R

  14. Analysis of the geological structure and tectonic evolution of Xingning-Jinghai sag in deep water area, northern South China Sea

    Science.gov (United States)

    Han, Xiaoying; Ren, Jianye; Lin, Zi; Yang, Linlong

    2015-04-01

    Recent years, oil and gas exploration of the Pearl River Mouth Basin in the northern margin of South China Sea continuously achieved historic breakthroughs. The Xingning-Jinghai sag, which is located in southeast of the Pearl River Mouth Basin, is a deep-water sag with a great exploration potential. Its tectonic evolution is extremely complex. It experienced Mesozoic subduction to Cenozoic intra-continental rifting background, and finally evolved into a deep-water sag of the northern continental margin of South China Sea. The geological characteristics and the tectonic evolution of Xingning-Jinghai sag was closely related to the process of formation and evolution of the passive continental margin of the northern South China Sea. It is confirmed by many geophysical data that compared with adjacent Chaoshan depression, the crustal thickness of Xingning-Jinghai sag was rapidly thinning, and it developed detachment faults with later magmatic intrusion. The development of detachment faults have dynamic significance for the spreading of the South China Sea. Based on the seismic geological interpretation of 2D seismic data in the study area, the characteristics of detachment fault and supra-detachment basin have been proposed in this study. The characteristics of the detachment fault are low angle and high ratio between heave and throw. The geometry of the detachment fault is a typical lisric shape, with the dip of fault decreasing generally from the seismic profile. The detachment basin where sediments are not deposited over a tilting hanging-wall block but onto a tectonically exhumed footwall which is different from the typical half graben basin. Seismic profiles indicate two different structural styles in the east and west part of Xingning-Jinghai sag. In the west of the sag, there developed two large detachment faults, which control their detachment basin systems and the typical H block, and the two detachment faults are dipping landward and seaward, respectively. In

  15. The Coevolution of Phycobilisomes: Molecular Structure Adapting to Functional Evolution

    Directory of Open Access Journals (Sweden)

    Fei Shi

    2011-01-01

    Full Text Available Phycobilisome is the major light-harvesting complex in cyanobacteria and red alga. It consists of phycobiliproteins and their associated linker peptides which play key role in absorption and unidirectional transfer of light energy and the stability of the whole complex system, respectively. Former researches on the evolution among PBPs and linker peptides had mainly focused on the phylogenetic analysis and selective evolution. Coevolution is the change that the conformation of one residue is interrupted by mutation and a compensatory change selected for in its interacting partner. Here, coevolutionary analysis of allophycocyanin, phycocyanin, and phycoerythrin and covariation analysis of linker peptides were performed. Coevolution analyses reveal that these sites are significantly correlated, showing strong evidence of the functional and structural importance of interactions among these residues. According to interprotein coevolution analysis, less interaction was found between PBPs and linker peptides. Our results also revealed the correlations between the coevolution and adaptive selection in PBS were not directly related, but probably demonstrated by the sites coupled under physical-chemical interactions.

  16. Mathematical Analysis of Genomic Evolution

    Directory of Open Access Journals (Sweden)

    Cedric Green

    2011-01-01

    Full Text Available Changes in nucleotide sequences, or mutations, accumulate from generation to generation in the genomes of all living organisms. The mutations can be advantageous, deleterious, or neutral. The goal of this project is to determine the amount of advantageous mutations it takes to get human (Homo sapiens DNA from the DNA of genetically distinct organisms. We do this by collecting the genomic data of such organisms, and estimating the amount of mutations it takes to transform yeast (Saccharomyces cerevisiae DNA to the DNA of a human. We calculate the typical number of mutations occurring annually through the organism's average life span and the average mutation rate. This allows us to determine the total number of mutations as well as the probability of advantageous mutations. Not surprisingly, this probability proves to be fairly small. A more precise estimate can be determined by accounting for the differences in the chromosomal structure and phenomena like horizontal gene transfer.

  17. Triadic conceptual structure of the maximum entropy approach to evolution.

    Science.gov (United States)

    Herrmann-Pillath, Carsten; Salthe, Stanley N

    2011-03-01

    Many problems in evolutionary theory are cast in dyadic terms, such as the polar oppositions of organism and environment. We argue that a triadic conceptual structure offers an alternative perspective under which the information generating role of evolution as a physical process can be analyzed, and propose a new diagrammatic approach. Peirce's natural philosophy was deeply influenced by his reception of both Darwin's theory and thermodynamics. Thus, we elaborate on a new synthesis which puts together his theory of signs and modern Maximum Entropy approaches to evolution in a process discourse. Following recent contributions to the naturalization of Peircean semiosis, pointing towards 'physiosemiosis' or 'pansemiosis', we show that triadic structures involve the conjunction of three different kinds of causality, efficient, formal and final. In this, we accommodate the state-centered thermodynamic framework to a process approach. We apply this on Ulanowicz's analysis of autocatalytic cycles as primordial patterns of life. This paves the way for a semiotic view of thermodynamics which is built on the idea that Peircean interpretants are systems of physical inference devices evolving under natural selection. In this view, the principles of Maximum Entropy, Maximum Power, and Maximum Entropy Production work together to drive the emergence of information carrying structures, which at the same time maximize information capacity as well as the gradients of energy flows, such that ultimately, contrary to Schrödinger's seminal contribution, the evolutionary process is seen to be a physical expression of the Second Law.

  18. Analysis of the complete DNA sequence of the temperate bacteriophage TP901-1: Evolution, structure, and genome organization of lactococcal bacteriophages

    DEFF Research Database (Denmark)

    Brøndsted, Lone; Østergaard, Solvej; Pedersen, Margit;

    2001-01-01

    A complete analysis of the entire genome of the temperate lactococcal bacteriophage TP901-1 has been performed and the function of 21 of 56 TP901-1-encoded ORFs has been assigned. This knowledge has been used to propose 10 functional modules each responsible for specific functions during bacterio......A complete analysis of the entire genome of the temperate lactococcal bacteriophage TP901-1 has been performed and the function of 21 of 56 TP901-1-encoded ORFs has been assigned. This knowledge has been used to propose 10 functional modules each responsible for specific functions during...... bacteriophage TP901-1 proliferation. Short regions of microhomology in intergenic regions present in several lactococcal bacteriophages and chromosomal fragments of Lactococcus lactis are suggested to be points of exchange of genetic material through homologous recombination. Our results indicate that TP901......-1 may have evolved by homologous recombination between the host chromosome and a mother phage and support the observation that phage remnants as well as prophages located in the Lactococcus chromosome contribute significantly to bacteriophage evolution. Some proteins encoded in the early transcribed...

  19. Social network analysis community detection and evolution

    CERN Document Server

    Missaoui, Rokia

    2015-01-01

    This book is devoted to recent progress in social network analysis with a high focus on community detection and evolution. The eleven chapters cover the identification of cohesive groups, core components and key players either in static or dynamic networks of different kinds and levels of heterogeneity. Other important topics in social network analysis such as influential detection and maximization, information propagation, user behavior analysis, as well as network modeling and visualization are also presented. Many studies are validated through real social networks such as Twitter. This edit

  20. Modeling Temporal Evolution and Multiscale Structure in Networks

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard

    2013-01-01

    -point model to account for the temporal evolution of each vertex. We demonstrate that our model is able to infer time-varying multiscale structure in synthetic as well as three real world time-evolving complex networks. Our modeling of the temporal evolution of hierarchies brings new insights...

  1. Shell evolution: A paradigm of structure of exotic nuclei?

    OpenAIRE

    Otsuka, Taka

    2003-01-01

    The evolution of shell structure and magic numbers of exotic nuclei are discussed with a rather pedagogical introduction. A major origin of the shell evolution is shown to be the spin-isospin dependent central part of the nucleon-nucleon interaction in nuclei. The importance and robustness of this mechanism ...

  2. Evolution and Structural Analyses of Glossina morsitans (Diptera; Glossinidae) Tetraspanins

    NARCIS (Netherlands)

    Murungi, E.K.; Kariithi, H.M.; Adunga, V.; Obonyo, M.; Christoffels, A.

    2014-01-01

    Tetraspanins are important conserved integral membrane proteins expressed in many organisms. Although there is limited knowledge about the full repertoire, evolution and structural characteristics of individual members in various organisms, data obtained so far show that tetraspanins play major role

  3. 我国海洋产业结构演化的过程研究%Analysis of Chinese Marine Industrial Structure Evolution and Optimization Based on the"Three Axis Diagram"Method

    Institute of Scientific and Technical Information of China (English)

    石秋艳

    2014-01-01

    海洋产业结构的优化升级是海洋经济健康持续发展的重要保障,并直接影响着人类未来的发展。在有关学者对海洋产业结构演化的研究基础之上,运用三轴图分析法,构建了海洋产业结构演进模式图,可直观清晰地看出我国海洋三次产业结构的动态演变过程,显示我国海洋产业结构已实现第三产业占据主导地位的三、二、一产业结构模式,并在此基础上对海洋产业结构的演化阶段进行分析。从加强国家宏观调控、优化产业布局、加强科技创新、建立人才队伍等方面提出优化海洋产业结构的对策。%Optimization and upgrading of industrial structure of the ocean is an important guarantee for develping marine economy healthly and sustainly which directly affecting the future development of mankind. Based on the research scholars of the evolution of the marine industry structure above, marine industrial structure evolution model diagram was constructed by using three-axis chart analysis.c The dynamic evolution of the industrial structure of China's three oceans can be revealed as following:The third industry has become the largest industrial sector in marine industry structure . The evolutionary stages of marine industrial structure were analyzed based on the above analysis. Finally, the marine industrial structure optimization strategies were put forward as the following:strengthening the national macro-control, optimizing the industrial layout, strengthening scientific and technological innovation, and establishing personnel.

  4. Structural evolution of the protein kinase-like superfamily.

    Directory of Open Access Journals (Sweden)

    Eric D Scheeff

    2005-10-01

    Full Text Available The protein kinase family is large and important, but it is only one family in a larger superfamily of homologous kinases that phosphorylate a variety of substrates and play important roles in all three superkingdoms of life. We used a carefully constructed structural alignment of selected kinases as the basis for a study of the structural evolution of the protein kinase-like superfamily. The comparison of structures revealed a "universal core" domain consisting only of regions required for ATP binding and the phosphotransfer reaction. Remarkably, even within the universal core some kinase structures display notable changes, while still retaining essential activity. Hence, the protein kinase-like superfamily has undergone substantial structural and sequence revision over long evolutionary timescales. We constructed a phylogenetic tree for the superfamily using a novel approach that allowed for the combination of sequence and structure information into a unified quantitative analysis. When considered against the backdrop of species distribution and other metrics, our tree provides a compelling scenario for the development of the various kinase families from a shared common ancestor. We propose that most of the so-called "atypical kinases" are not intermittently derived from protein kinases, but rather diverged early in evolution to form a distinct phyletic group. Within the atypical kinases, the aminoglycoside and choline kinase families appear to share the closest relationship. These two families in turn appear to be the most closely related to the protein kinase family. In addition, our analysis suggests that the actin-fragmin kinase, an atypical protein kinase, is more closely related to the phosphoinositide-3 kinase family than to the protein kinase family. The two most divergent families, alpha-kinases and phosphatidylinositol phosphate kinases (PIPKs, appear to have distinct evolutionary histories. While the PIPKs probably have an

  5. Structural Evolution of the Protein Kinase-Like Superfamily.

    Directory of Open Access Journals (Sweden)

    2005-10-01

    Full Text Available The protein kinase family is large and important, but it is only one family in a larger superfamily of homologous kinases that phosphorylate a variety of substrates and play important roles in all three superkingdoms of life. We used a carefully constructed structural alignment of selected kinases as the basis for a study of the structural evolution of the protein kinase-like superfamily. The comparison of structures revealed a "universal core" domain consisting only of regions required for ATP binding and the phosphotransfer reaction. Remarkably, even within the universal core some kinase structures display notable changes, while still retaining essential activity. Hence, the protein kinase-like superfamily has undergone substantial structural and sequence revision over long evolutionary timescales. We constructed a phylogenetic tree for the superfamily using a novel approach that allowed for the combination of sequence and structure information into a unified quantitative analysis. When considered against the backdrop of species distribution and other metrics, our tree provides a compelling scenario for the development of the various kinase families from a shared common ancestor. We propose that most of the so-called "atypical kinases" are not intermittently derived from protein kinases, but rather diverged early in evolution to form a distinct phyletic group. Within the atypical kinases, the aminoglycoside and choline kinase families appear to share the closest relationship. These two families in turn appear to be the most closely related to the protein kinase family. In addition, our analysis suggests that the actin-fragmin kinase, an atypical protein kinase, is more closely related to the phosphoinositide-3 kinase family than to the protein kinase family. The two most divergent families, alpha-kinases and phosphatidylinositol phosphate kinases (PIPKs, appear to have distinct evolutionary histories. While the PIPKs probably have an

  6. Modified structure of graphene oxide by investigation of structure evolution

    Indian Academy of Sciences (India)

    A Nekahi; S P H Marashi; D Haghshenas Fatmesari

    2015-12-01

    The structure of graphite oxide and graphene oxide (GO) has been studied previously using various analyses and computer simulations. Although some oxygen functional groups (OFGs) are accepted as the main functionalities in GO, the structure of GO has remained elusive. In this regard, GO was produced using the modified Hummers method and was investigated using X-ray diffraction pattern, Fourier transform infrared analysis and Boehm titration method. Based on the obtained results, a modified model was proposed for GO based on the model of Lerf-Klinowski. OFGs include highly carboxyl groups and phenols with few epoxides, lactones and ketones agglomerated in some regions due to hydrogen bonding between functional groups. Trapped water molecules were shown between the GO sheets which strongly affected the distribution of OFGs and their aggregation by hydrogen bonding.

  7. Structural evolution of small ruthenium cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Waldt, Eugen [Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany); Hehn, Anna-Sophia; Ahlrichs, Reinhart [Institute für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstrasse 12, 76128 Karlsruhe (Germany); Kappes, Manfred M.; Schooss, Detlef, E-mail: detlef.schooss@kit.edu [Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany); Institute für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstrasse 12, 76128 Karlsruhe (Germany)

    2015-01-14

    The structures of ruthenium cluster anions have been investigated using a combination of trapped ion electron diffraction and density functional theory computations in the size range from eight to twenty atoms. In this size range, three different structural motifs are found: Ru{sub 8}{sup −}–Ru{sub 12}{sup −} have simple cubic structures, Ru{sub 13}{sup −}–Ru{sub 16}{sup −} form double layered hexagonal structures, and larger clusters form close packed motifs. For Ru{sub 17}{sup −}, we find hexagonal close packed stacking, whereas octahedral structures occur for Ru{sub 18}{sup −}–Ru{sub 20}{sup −}. Our calculations also predict simple cubic structures for the smaller clusters Ru{sub 4}{sup −}–Ru{sub 7}{sup −}, which were not accessible to electron diffraction measurements.

  8. Structure, Evolution and Nucleosynthesis of Primordial Stars

    CERN Document Server

    Siess, L; Lattanzio, J C; Siess, Lionel; Livio, Mario; Lattanzio, John

    2002-01-01

    (abridge version) The evolution of population III stars (Z=0) is followed from the pre-main sequence phase up to the AGB phase for intermediate-mass stars and up to C ignition in more massive stars...We find that, thanks to the development of mixing episodes (carbon injections) at the beginning of the AGB phase, the carbon abundance of the 1, 1.5, 2, 3, 4 and 5Mo models is significantly increased in the envelope. This process then allows low- and intermediate-mass stars to achieve a ``standard'' thermally pulsing AGB phase... In the 7Mo model, the CNO envelope abundance following the second dredge-up is so large that the star does not experience the carbon injection episode and follows a more standard thermally pulsing AGB evolution. Our computations also indicate that, thanks to a small overshooting at the base of the convective envelope, the third dredge-up is already operating in stars with M >~1.5 Mo after a few pulses, and that by the end of our modeling, hot bottom burning is activated in stars more mas...

  9. Structural analysis for Diagnosis

    DEFF Research Database (Denmark)

    Izadi-Zamanabadi, Roozbeh; Blanke, M.

    2001-01-01

    Aiming at design of algorithms for fault diagnosis, structural analysis of systems offers concise yet easy overall analysis. Graph-based matching, which is the essential technique to obtain redundant information for diagnosis, is re-considered in this paper. Matching is re-formulated as a problem...

  10. Evolution of extortion in structured populations

    CERN Document Server

    Szolnoki, Attila

    2014-01-01

    Extortion strategies can dominate any opponent in an iterated prisoner's dilemma game. But if players are able to adopt the strategies performing better, extortion becomes widespread and evolutionary unstable. It may sometimes act as a catalyst for the evolution of cooperation, and it can also emerge in interactions between two populations, yet it is not the evolutionary stable outcome. Here we revisit these results in the realm of spatial games. We find that pairwise imitation and birth-death dynamics return known evolutionary outcomes. Myopic best response strategy updating, on the other hand, reveals new counterintuitive solutions. Defectors and extortioners coarsen spontaneously, which allows cooperators to prevail even at prohibitively high temptations to defect. Here extortion strategies play the role of a Trojan horse. They may emerge among defectors by chance, and once they do, cooperators become viable as well. These results are independent of the interaction topology, and they highlight the importan...

  11. Mixing biases: Structural changes in the as topology evolution

    NARCIS (Netherlands)

    Haddadi, H.; Fay, D.; Uhlig, S.; Moore, A.; Mortier, R.; Jamakovic, A.

    2010-01-01

    In this paper we study the structural evolution of the AS topology as inferred from two different datasets over a period of seven years. We use a variety of topological metrics to analyze the structural differences revealed in the AS topologies inferred from the two different datasets. In particular

  12. BAK-SNEPPEN MODELS FOR THE EVOLUTION OF STRUCTURED KNOWLEDGE

    OpenAIRE

    Piccinini, Livio Clemente; Chang, Ting Fa Margherita; Lepellere, Maria Antonietta; Taverna, Mario; Tubaro, Giovanni

    2016-01-01

    Scientific knowledge is subject to a twin evolution, since its development towards novelty creates disconnections and inconsistencies, while the need of structure requires order and method so that transmission and comprehension can be ensured. Models of biological evolution can help to understand many social and economical phenomena where the search for optimality is hindered by voluntary or random competition. Bak-Sneppen is one of the most significant models because it balances at best expl...

  13. Evolution of Sex-Ratio in Structured Population Dynamics

    OpenAIRE

    Ripoll i Missé, Jordi

    2005-01-01

    In this Thesis we address the study of some non-linear evolution equations (e.g. pde's) modelling the dynamics of sexually-reproducing structured populations, with special emphasis on biological evolution driven by natural selection. The latter is incorporated into the models through the adaptive dynamics, which is a way of describing how the hereditary characteristics of the population evolve. The sex-ratio, defined as the proportion between females and males, is analyzed from the evolutiona...

  14. Evol and ProDy for bridging protein sequence evolution and structural dynamics

    OpenAIRE

    Bakan, Ahmet; Dutta, Anindita; Mao, Wenzhi; Liu, Ying; Chennubhotla, Chakra; Lezon, Timothy R.; Bahar, Ivet

    2014-01-01

    Correlations between sequence evolution and structural dynamics are of utmost importance in understanding the molecular mechanisms of function and their evolution. We have integrated Evol, a new package for fast and efficient comparative analysis of evolutionary patterns and conformational dynamics, into ProDy, a computational toolbox designed for inferring protein dynamics from experimental and theoretical data. Using information-theoretic approaches, Evol coanalyzes conservation and coevolu...

  15. Analysis of DCC domain structure

    International Nuclear Information System (INIS)

    Wavelet-type methods are employed for the analysis of pion field configurations that have been obtained by dynamical simulations in idealized scenarios relevant to the formation of disoriented chiral condensates. It is illustrated how the measurement of the isospin domain structure depends on the ability to zoom in on limited parts of the phase space, due to the interplay between the pion correlation length and the effective source geometry. The need for advanced analysis methods is underscored by the fact that the extracted neutral-fraction distribution would differ significantly from the ideal form, even under perfect experimental conditions, and, moreover, by the circumstance that thermal sources with suitably adjusted temperatures can lead to distributions that may be practically indistinguishable from those arising from DCC-type nonequilibrium evolutions. copyright 1997 The American Physical Society

  16. Evolution Analysis About Soybean MIR166 Family

    Institute of Scientific and Technical Information of China (English)

    Wang Zhi-hao; Jin Hui-hui; Chen Qing-shan; Zhu Rong-sheng

    2015-01-01

    MicroRNA (miRNA) is a class of important regulating non-coding small molecular RNA. The gma-MIR166 gene family consists of 21 members and their expression patterns diversify widely. It is important to analyze the evolution of gma-MIR166 gene family in order to understand the evolutionary mechanisms of miRNAs in soybean. In this study, we implemented soybean wide genome block analysis, the molecular phylogeny of gma-MIR166 and block analysis of gma-MIR166 family. The results showed that both chromosome big segmental duplications and tandem duplications were main reasons contributed to the expanding of gma-MIR166 gene family. These findings suggested that gma-MIR166 gene family might originate from one or two ancient miRNA genes. The results of research provided a support for evolutionary study of miRNAs in soybean and related species in Fabaceae.

  17. Evolution of atomic structure during nanoparticle formation

    Directory of Open Access Journals (Sweden)

    Christoffer Tyrsted

    2014-05-01

    Full Text Available Understanding the mechanism of nanoparticle formation during synthesis is a key prerequisite for the rational design and engineering of desirable materials properties, yet remains elusive due to the difficulty of studying structures at the nanoscale under real conditions. Here, the first comprehensive structural description of the formation of a nanoparticle, yttria-stabilized zirconia (YSZ, all the way from its ionic constituents in solution to the final crystal, is presented. The transformation is a complicated multi-step sequence of atomic reorganizations as the material follows the reaction pathway towards the equilibrium product. Prior to nanoparticle nucleation, reagents reorganize into polymeric species whose structure is incompatible with the final product. Instead of direct nucleation of clusters into the final product lattice, a highly disordered intermediate precipitate forms with a local bonding environment similar to the product yet lacking the correct topology. During maturation, bond reforming occurs by nucleation and growth of distinct domains within the amorphous intermediary. The present study moves beyond kinetic modeling by providing detailed real-time structural insight, and it is demonstrated that YSZ nanoparticle formation and growth is a more complex chemical process than accounted for in conventional models. This level of mechanistic understanding of the nanoparticle formation is the first step towards more rational control over nanoparticle synthesis through control of both solution precursors and reaction intermediaries.

  18. Structural Approaches to Sequence Evolution Molecules, Networks, Populations

    CERN Document Server

    Bastolla, Ugo; Roman, H. Eduardo; Vendruscolo, Michele

    2007-01-01

    Structural requirements constrain the evolution of biological entities at all levels, from macromolecules to their networks, right up to populations of biological organisms. Classical models of molecular evolution, however, are focused at the level of the symbols - the biological sequence - rather than that of their resulting structure. Now recent advances in understanding the thermodynamics of macromolecules, the topological properties of gene networks, the organization and mutation capabilities of genomes, and the structure of populations make it possible to incorporate these key elements into a broader and deeply interdisciplinary view of molecular evolution. This book gives an account of such a new approach, through clear tutorial contributions by leading scientists specializing in the different fields involved.

  19. Dynamic structure evolution of time-dependent network

    Science.gov (United States)

    Zhang, Beibei; Zhou, Yadong; Xu, Xiaoyan; Wang, Dai; Guan, Xiaohong

    2016-08-01

    In this paper, we research the long-voided problem of formulating the time-dependent network structure evolution scheme, it focus not only on finding new emerging vertices in evolving communities and new emerging communities over the specified time range but also formulating the complex network structure evolution schematic. Previous approaches basically applied to community detection on time static networks and thus failed to consider the potentially crucial and useful information latently embedded in the dynamic structure evolution process of time-dependent network. To address these problems and to tackle the network non-scalability dilemma, we propose the dynamic hierarchical method for detecting and revealing structure evolution schematic of the time-dependent network. In practice and specificity, we propose an explicit hierarchical network evolution uncovering algorithm framework originated from and widely expanded from time-dependent and dynamic spectral optimization theory. Our method yields preferable results compared with previous approaches on a vast variety of test network data, including both real on-line networks and computer generated complex networks.

  20. Firn Structure Evolution at WAIS Divide

    Science.gov (United States)

    Harwell, E. N.; Albert, M. R.; Gregory, S.; Keegan, K. M.

    2013-12-01

    The polar ice sheets serve as natural archives of past climate, as well as sensitive indicators of current climate change. The physical structure of snow and firn is sensitive to local environmental changes. The top 60-120 m of wide expanses of the Greenland and Antarctic ice sheets consists of firn, snow that is more than a year old. This porous structure serves as a natural archive of past atmospheric composition and plays an important role in the initiation of the ice core record of past atmospheres, and also plays a key role in remote sensing. This paper examines the physical nature of firn at the WAIS Divide ice core site in West Antarctica. Measurements of the density and permeability profiles are reported from the surface over the depth of the firn column profile. The WAIS Divide ice core site was chosen to be the Antarctic analog of the high-resolution GISP2 core from Summit, Greenland; both sites are cold sites with high accumulation rates. We describe similarities and differences in the structure of firn by comparing measurements from WAIS Divide and Summit, and we identify causes for differences.

  1. Modelling the Evolution of Social Structure

    Science.gov (United States)

    Sutcliffe, A. G.; Dunbar, R. I. M.; Wang, D.

    2016-01-01

    Although simple social structures are more common in animal societies, some taxa (mainly mammals) have complex, multi-level social systems, in which the levels reflect differential association. We develop a simulation model to explore the conditions under which multi-level social systems of this kind evolve. Our model focuses on the evolutionary trade-offs between foraging and social interaction, and explores the impact of alternative strategies for distributing social interaction, with fitness criteria for wellbeing, alliance formation, risk, stress and access to food resources that reward social strategies differentially. The results suggest that multi-level social structures characterised by a few strong relationships, more medium ties and large numbers of weak ties emerge only in a small part of the overall fitness landscape, namely where there are significant fitness benefits from wellbeing and alliance formation and there are high levels of social interaction. In contrast, ‘favour-the-few’ strategies are more competitive under a wide range of fitness conditions, including those producing homogeneous, single-level societies of the kind found in many birds and mammals. The simulations suggest that the development of complex, multi-level social structures of the kind found in many primates (including humans) depends on a capacity for high investment in social time, preferential social interaction strategies, high mortality risk and/or differential reproduction. These conditions are characteristic of only a few mammalian taxa. PMID:27427758

  2. Modelling the Evolution of Social Structure.

    Directory of Open Access Journals (Sweden)

    A G Sutcliffe

    Full Text Available Although simple social structures are more common in animal societies, some taxa (mainly mammals have complex, multi-level social systems, in which the levels reflect differential association. We develop a simulation model to explore the conditions under which multi-level social systems of this kind evolve. Our model focuses on the evolutionary trade-offs between foraging and social interaction, and explores the impact of alternative strategies for distributing social interaction, with fitness criteria for wellbeing, alliance formation, risk, stress and access to food resources that reward social strategies differentially. The results suggest that multi-level social structures characterised by a few strong relationships, more medium ties and large numbers of weak ties emerge only in a small part of the overall fitness landscape, namely where there are significant fitness benefits from wellbeing and alliance formation and there are high levels of social interaction. In contrast, 'favour-the-few' strategies are more competitive under a wide range of fitness conditions, including those producing homogeneous, single-level societies of the kind found in many birds and mammals. The simulations suggest that the development of complex, multi-level social structures of the kind found in many primates (including humans depends on a capacity for high investment in social time, preferential social interaction strategies, high mortality risk and/or differential reproduction. These conditions are characteristic of only a few mammalian taxa.

  3. STRUCTURAL EVOLUTION IN BIORENEWABLE SOY BASED POLYURETHANES

    Institute of Scientific and Technical Information of China (English)

    Deepa Puthanparambil; Casey Kimball; Shaw Ling Hsu; Zhiyong Ren

    2009-01-01

    Spectroscopic studies have revealed that the amount of polyureas formed and the kinetics of their formation in soy based polyurethane systems are considerably different from traditional systems employing ethylene oxide-propylene oxide (EO-PO) based polyols. The aggregation of polyureas was characterized by the hydrogen bonds formed utilizing FTIR spectroscopy. This study offered the opportunity to assign the previously undefined infrared features. The structural transformation is reflected in the segmental relaxation kinetics characterized by spin-spin diffusion most conveniently measured using low field NMR. The reaction kinetics and the products formed are directly related to the hydrophobic nature of the soy based polyols and its inability to disperse water.

  4. Structural analysis of DAEs

    DEFF Research Database (Denmark)

    Poulsen, Mikael Zebbelin

    2002-01-01

    , by the implementation of the Simpy tool box. This is an object oriented system implemented in the Python language. It can be used for analysis of DAEs, ODEs and non-linear equation and uses e.g. symbolic representations of expressions and equations. The presentations of theory and algorithms for structural index...

  5. Structural Evolution of Interstellar Polycyclic Aromatic Hydrocarbons

    Science.gov (United States)

    Hammonds, Mark; Candian, Alessandra; Mori, Tamami; Usui, Fumihiko; Onaka, Takashi

    2015-08-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are an important reservoir for molecular carbon in the interstellar medium (ISM), and investigations into their chemistry and behaviour may be important to the understanding of how carbon is processed from simple forms into complex prebiotic molecules such as those detected in chondritic meteorites. In this study, infrared astronomical data from AKARI and other observatories are used together with laboratory and theoretical data to study variations in the structure of emitting PAHs in interstellar environments using spectroscopic decomposition techniques and bands arising from carbon-hydrogen bond vibrations at wavelengths from 3 - 14 microns. Results and inferences are discussed in terms of the processing of large carbonaceous molecules in astrophysical environments.

  6. Design Evolution and Analysis of the ITER Cryostat Support System

    Science.gov (United States)

    Xie, Han; Song, Yuntao; Wang, Songke

    2015-12-01

    The cryostat is a vacuum tight container enveloping the entire basic systems of the ITER tokamak machine, including a vacuum vessel, a superconducting magnet and thermal shield etc. It is evacuated to a pressure of 10-4 Pa to limit the heat transfer via gas conduction and convection to the cryogenically cooled components. Another important function of cryostat is to support all the loads from the tokamak to the concrete floor of the pit by its support system during different operational regimes and accident scenarios. This paper briefly presents the design evolution and associated analysis of the cryostat support system and the structural interface with the building.

  7. Structure, Function, and Evolution of Rice Centromeres

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jiming

    2010-02-04

    The centromere is the most characteristic landmark of eukaryotic chromosomes. Centromeres function as the site for kinetochore assembly and spindle attachment, allowing for the faithful pairing and segregation of sister chromatids during cell division. Characterization of centromeric DNA is not only essential to understand the structure and organization of plant genomes, but it is also a critical step in the development of plant artificial chromosomes. The centromeres of most model eukaryotic species, consist predominantly of long arrays of satellite DNA. Determining the precise DNA boundary of a centromere has proven to be a difficult task in multicellular eukaryotes. We have successfully cloned and sequenced the centromere of rice chromosome 8 (Cen8), representing the first fully sequenced centromere from any multicellular eukaryotes. The functional core of Cen8 spans ~800 kb of DNA, which was determined by chromatin immunoprecipitation (ChIP) using an antibody against the rice centromere-specific H3 histone. We discovered 16 actively transcribed genes distributed throughout the Cen8 region. In addition to Cen8, we have characterized eight additional rice centromeres using the next generation sequencing technology. We discovered four subfamilies of the CRR retrotransposon that is highly enriched in rice centromeres. CRR elements are constitutively transcribed and different CRR subfamilies are differentially processed by RNAi. These results suggest that different CRR subfamilies may play different roles in the RNAi-mediated pathway for formation and maintenance of centromeric chromatin.

  8. Structural evolution of Colloidal Gels under Flow

    Science.gov (United States)

    Boromand, Arman; Maia, Joao; Jamali, Safa

    Colloidal suspensions are ubiquitous in different industrial applications ranging from cosmetic and food industries to soft robotics and aerospace. Owing to the fact that mechanical properties of colloidal gels are controlled by its microstructure and network topology, we trace the particles in the networks formed under different attraction potentials and try to find a universal behavior in yielding of colloidal gels. Many authors have implemented different simulation techniques such as molecular dynamics (MD) and Brownian dynamics (BD) to capture better picture during phase separation and yielding mechanism in colloidal system with short-ranged attractive force. However, BD neglects multi-body hydrodynamic interactions (HI) which are believed to be responsible for the second yielding of colloidal gels. We envision using dissipative particle dynamics (DPD) with modified depletion potential and hydrodynamic interactions, as a coarse-grain model, can provide a robust simulation package to address the gel formation process and yielding in short ranged-attractive colloidal systems. The behavior of colloidal gels with different attraction potentials under flow is examined and structural fingerprints of yielding in these systems will be discussed.

  9. Prolongation Structure of Semi-discrete Nonlinear Evolution Equations

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on noncommutative differential calculus, we present a theory of prolongation structure for semi-discrete nonlinear evolution equations. As an illustrative example, a semi-discrete model of the nonlinear Schr(o)dinger equation is discussed in terms of this theory and the corresponding Lax pairs are also given.

  10. Rehabilitation Counselor Education Accreditation: History, Structure, and Evolution

    Science.gov (United States)

    Shaw, Linda R.; Kuehn, Marvin D.

    2009-01-01

    This review examines some of the critical factors that influenced the evolution of rehabilitation counselor education accreditation. The article discusses the history and structure of the accreditation process and the activities that have occurred to maintain the relevancy and viability of the process. Major issues that the Council on…

  11. The Evolution of Protein Structures and Structural Ensembles Under Functional Constraint

    OpenAIRE

    Liberles, David A; Grahnen, Johan A.; Jessica Siltberg-Liberles

    2011-01-01

    Protein sequence, structure, and function are inherently linked through evolution and population genetics. Our knowledge of protein structure comes from solved structures in the Protein Data Bank (PDB), our knowledge of sequence through sequences found in the NCBI sequence databases (http://www.ncbi.nlm.nih.gov/), and our knowledge of function through a limited set of in-vitro biochemical studies. How these intersect through evolution is described in the first part of the review. In the secon...

  12. Evolution and physics in comparative protein structure modeling.

    Science.gov (United States)

    Fiser, András; Feig, Michael; Brooks, Charles L; Sali, Andrej

    2002-06-01

    From a physical perspective, the native structure of a protein is a consequence of physical forces acting on the protein and solvent atoms during the folding process. From a biological perspective, the native structure of proteins is a result of evolution over millions of years. Correspondingly, there are two types of protein structure prediction methods, de novo prediction and comparative modeling. We review comparative protein structure modeling and discuss the incorporation of physical considerations into the modeling process. A good starting point for achieving this aim is provided by comparative modeling by satisfaction of spatial restraints. Incorporation of physical considerations is illustrated by an inclusion of solvation effects into the modeling of loops.

  13. Structural evolution of silica sols modified with formamide

    Directory of Open Access Journals (Sweden)

    Lenza R.F.S.

    2001-01-01

    Full Text Available In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR. Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH stretching vibration at around 950 cm-1 and the Si-O-(Si vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.

  14. Structural dynamics analysis

    Science.gov (United States)

    Housner, J. M.; Anderson, M.; Belvin, W.; Horner, G.

    1985-01-01

    Dynamic analysis of large space antenna systems must treat the deployment as well as vibration and control of the deployed antenna. Candidate computer programs for deployment dynamics, and issues and needs for future program developments are reviewed. Some results for mast and hoop deployment are also presented. Modeling of complex antenna geometry with conventional finite element methods and with repetitive exact elements is considered. Analytical comparisons with experimental results for a 15 meter hoop/column antenna revealed the importance of accurate structural properties including nonlinear joints. Slackening of cables in this antenna is also a consideration. The technology of designing actively damped structures through analytical optimization is discussed and results are presented.

  15. Evolution of Analysis of Polyhenols from Grapes, Wines, and Extracts

    Directory of Open Access Journals (Sweden)

    Pierre-Louis Teissedre

    2013-01-01

    Full Text Available Grape and wine phenolics are structurally diverse, from simple molecules to oligomers and polymers usually designated as tannins. They have an important impact on the organoleptic properties of wines, that’s why their analysis and quantification are of primordial importance. The extraction of phenolics from grapes and from wines is the first step involved in the analysis. Then, several analytical methods have been developed for the determination of total content of phenolic, while chromatographic and spectrophotometric analyses are continuously improved in order to achieve adequate separation of phenolic molecules, their subsequent identification and quantification. This review provides a summary of evolution of analysis of polyphenols from grapes, wines and extracts.

  16. Structural evolution of zirconium carbide under ion irradiation

    Science.gov (United States)

    Gosset, D.; Dollé, M.; Simeone, D.; Baldinozzi, G.; Thomé, L.

    2008-02-01

    Zirconium carbide is one of the candidate materials to be used for some fuel components of the high temperature nuclear reactors planned in the frame of the Gen-IV project. Few data exist regarding its behaviour under irradiation. We have irradiated ZrC samples at room temperature with slow heavy ions (4 MeV Au, fluence from 10 11 to 5 × 10 15 cm -2) in order to simulate neutron irradiations. Grazing incidence X-Ray diffraction (GIXRD) and transmission electron microscopy (TEM) analysis have been performed in order to study the microstructural evolution of the material versus ion fluence. A high sensitivity to oxidation is observed with the formation of zirconia precipitates during the ion irradiations. Three damage stages are observed. At low fluence (high micro-strains appear together with small faulted dislocation loops. At the highest fluence (>10 14 cm -2), the micro-strains saturate and the loops coalesce to form a dense dislocation network. No other structural modification is observed. The material shows a moderate cell parameter increase, corresponding to a 0.6 vol.% swelling, which saturates around 10 14 ions/cm 2, i.e., a few Zr dpa. As a result, in spite of a strong covalent bonding component, ZrC seems to have a behaviour under irradiation close to cubic metals.

  17. THE STRUCTURE, ORIGIN, AND EVOLUTION OF INTERSTELLAR HYDROCARBON GRAINS

    Energy Technology Data Exchange (ETDEWEB)

    Chiar, J. E.; Ricca, A. [SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, CA 94043 (United States); Tielens, A. G. G. M. [Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Adamson, A. J., E-mail: jchiar@seti.org, E-mail: Alessandra.Ricca@1.nasa.gov, E-mail: tielens@strw.leidenuniv.nl, E-mail: aadamson@gemini.edu [Gemini Observatory, Northern Operations Center, 670 North A' ohoku Place, Hilo, HI 96729 (United States)

    2013-06-10

    Many materials have been considered for the carrier of the hydrocarbon absorption bands observed in the diffuse interstellar medium (ISM). In order to refine the model for ISM hydrocarbon grains, we analyze the observed aromatic (3.28, 6.2 {mu}m) and aliphatic (3.4 {mu}m) hydrocarbon absorption features in the diffuse ISM along the line of sight toward the Galactic center Quintuplet Cluster. Observationally, sp {sup 2} bonds can be measured in astronomical spectra using the 6.2 {mu}m CC aromatic stretch feature, whereas the 3.4 {mu}m aliphatic feature can be used to quantify the fraction of sp {sup 3} bonds. The fractional abundance of these components allows us to place the Galactic diffuse ISM hydrocarbons on a ternary phase diagram. We conclude that the Galactic hydrocarbon dust has, on average, a low H/C ratio and sp {sup 3} content and is highly aromatic. We have placed the results of our analysis within the context of the evolution of carbon dust in the ISM. We argue that interstellar carbon dust consists of a large core of aromatic carbon surrounded by a thin mantle of hydrogenated amorphous carbon (a-C:H), a structure that is a natural consequence of the processing of stardust grains in the ISM.

  18. Computational Analysis for Morphological Evolution in Pyrolysis for Micro/Nanofabrication

    Directory of Open Access Journals (Sweden)

    Myeongseok Yang

    2015-01-01

    Full Text Available Pyrolysis is recently proposed as an efficient fabrication technique of micro/nanoscale carbon structures. In order to understand the morphological evolution in pyrolysis and design the final shape of carbon structure, this study proposes a comprehensive model that incorporates the essential mechanisms of pyrolysis based on the phase field framework. Computational analysis with the developed model provides information about the effect of interface energy and kinetic rate on the morphological evolution in pyrolysis.

  19. The Liaonan Metamorphic Core Complex: Constitution, Structure and Evolution

    Institute of Scientific and Technical Information of China (English)

    LIU Junlai; GUAN Huimei; JI Mo; CAO Shuyun; HU Ling

    2006-01-01

    The Liaonan metamorphic core complex (mcc) has a three-layer structure and is constituted by five parts, i.e. a detachment fault zone, an allochthonous upper plate and an supradetachment basin above the fault zone, and highly metamorphosed rocks and intrusive rocks in the lower plate. The allochthonous upper plate is mainly of Neoproterozoic and Paleozoic rocks weakly deformed and metamorphosed in pre-Indosinan stage. Above these rocks is a small-scale supradetachment basin of Cretaceous sedimentary and volcanic rocks. The lower plate is dominated by Archean TTG gneisses with minor amount of supracrustal rocks. The Archean rocks are intruded by late Mesozoic synkinematic monzogranitic and granitic plutons. Different types of fault rocks, providing clues to the evolution of the detachment fault zone, are well-preserved in the fault zone, e.g. mylonitic gneiss,mylonites, brecciated mylonites, microbreccias and pseudotachylites. Lineations in lower plate granitic intrusions have consistent orientation that indicate uniform top-to-NW shearing along the main detachment fault zone. This also provides evidence for the synkinematic characteristics of the granitic plutons in the lower plate. Structural analysis of the different parts in the mcc and isotopic dating of plutonic rocks from the lower plate and mylonitic rocks from detachment fault zone suggest that exhumation of the mcc started with regional crustal extension due to crustal block rotation and tangential shearing. The extension triggered magma formation, upwelling and emplacement. This event ended with appearance of pseudotachylite and fault gauges formed at the uppermost crustal level.U-Pb dating of single zircon grains from granitic rocks in the lower plate gives an age of 130±5 Ma, and biotite grains from the main detachment fault zone have 40Ar-39Ar ages of 108-119 Ma. Several aspects may provide constraints for the exhumation of the Liaonan mcc. These include regional extensional setting, cover

  20. Subsurface defects structural evolution in nano-cutting of single crystal copper

    International Nuclear Information System (INIS)

    Highlights: • An innovative analysis method is adopted to analyze nano-cutting process accurately. • A characteristic SFT and stair-rod dislocation are found in subsurface defect layer. • The formation mechanism of stair-rod dislocation is investigated. • The local atomic structure of subsurface defects is introduced. - Abstract: In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, “V-shaped” dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated

  1. Subsurface defects structural evolution in nano-cutting of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Quanlong [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bai, Qingshun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chen, Jiaxuan, E-mail: wangquanlong0@hit.edu.cn [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Yazhou [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Yongbo [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liang, Yingchun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-07-30

    Highlights: • An innovative analysis method is adopted to analyze nano-cutting process accurately. • A characteristic SFT and stair-rod dislocation are found in subsurface defect layer. • The formation mechanism of stair-rod dislocation is investigated. • The local atomic structure of subsurface defects is introduced. - Abstract: In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, “V-shaped” dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated.

  2. Voronoi Structural Evolution of Bulk Silicon upon Melting

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shi-Liang; ZHANG Xin-Yu; WANG Lin-Min; QI Li; ZHANG Su-Hong; ZHU Yan; LIU Ri-Ping

    2011-01-01

    @@ The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation.At temperatures below the melting point, the solid state system is identified to have a four-fold coordination structure .As the temperature increases, the five-fold coordination and six-fold coordination structures and are observed.This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others.At temperatures above the melting point, nearly ali of the four-fold coordination structures grows into multiple-fold coordination ones.%The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation. At temperatures below the melting point, the solid state system is identified to have a four-told coordination structure (4,0,0,0). As the temperature increases, the five-fold coordination (2,3,0,0) and six-fold coordination structures (2,2,2,0) and (0,6,0,0) are observed. This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others. At temperatures above the melting point, nearly all of the four-fold coordination structures grows into multiple-fold coordination ones.

  3. Simulated evolution of the dark matter large-scale structure

    CERN Document Server

    Demiański, M; Pilipenko, S; Gottlöber, S

    2011-01-01

    We analyze evolution of the basic properties of simulated large scale structure elements formed by dark matter (DM LSS) and confront it with the observed evolution of the Lyman-$\\alpha$ forest. In three high resolution simulations we selected samples of compact DM clouds of moderate overdensity. Clouds are selected at redshifts $0\\leq z\\leq 3$ with the Minimal Spanning Tree (MST) technique. The main properties of so selected clouds are analyzed in 3D space and with the core sampling approach, what allows us to compare estimates of the DM LSS evolution obtained with two different techniques and to clarify some important aspects of the LSS evolution. In both cases we find that regular redshift variations of the mean characteristics of the DM LSS are accompanied only by small variations of their PDFs, what indicates the self similar character of the DM LSS evolution. The high degree of relaxation of DM particles compressed within the LSS is found along the shortest principal axis of clouds. We see that the inter...

  4. Protoplanetary Disk Structure With Grain Evolution: the ANDES Model

    CERN Document Server

    Akimkin, V; Wiebe, D; Semenov, D; Pavlyuchenkov, Ya; Vasyunin, A; Birnstiel, T; Henning, Th

    2013-01-01

    We present a self-consistent model of a protoplanetary disk: 'ANDES' ('AccretioN disk with Dust Evolution and Sedimentation'). ANDES is based on a flexible and extendable modular structure that includes 1) a 1+1D frequency-dependent continuum radiative transfer module, 2) a module to calculate the chemical evolution using an extended gas-grain network with UV/X-ray-driven processes surface reactions, 3) a module to calculate the gas thermal energy balance, and 4) a 1+1D module that simulates dust grain evolution. For the first time, grain evolution and time-dependent molecular chemistry are included in a protoplanetary disk model. We find that grain growth and sedimentation of large grains to the disk midplane lead to a dust-depleted atmosphere. Consequently, dust and gas temperatures become higher in the inner disk (R 50 AU), in comparison with the disk model with pristine dust. The response of disk chemical structure to the dust growth and sedimentation is twofold. First, due to higher transparency a partl...

  5. Fault Wear and Friction Evolution: Experimental Analysis

    Science.gov (United States)

    Boneh, Y.; Chang, J. C.; Lockner, D. A.; Reches, Z.

    2011-12-01

    Wear is an inevitable product of frictional sliding of brittle rocks as evidenced by the ubiquitous occurrence of fault gouge and slickenside striations. We present here experimental observations designed to demonstrate the relationship between wear and friction and their governing mechanisms. The experiments were conducted with a rotary shear apparatus on solid, ring-shaped rock samples that slipped for displacements up to tens of meters. Stresses, wear and temperature were continuously monitored. We analyzed 86 experiments of Kasota dolomite, Sierra White granite, Pennsylvania quartzite, Karoo gabbro, and Tennessee sandstone at slip velocities ranging from 0.002 to 0.97 m/s, and normal stress from 0.25 to 6.9 MPa. We conducted two types of runs: short slip experiments (slip distance wear mechanisms; and long slip experiments (slip distance > 3 m) designed to achieve mature wear conditions and to observe the evolution of wear and friction as the fault surfaces evolved. The experiments reveal three wear stages: initial, running-in, and steady-state. The initial stage is characterized by (1) discrete damage striations, the length of which is comparable to total slip , and local pits or plow features; (2) timing and magnitude of fault-normal dilation corresponds to transient changes of normal and shear stresses; and (3) surface roughness increasing with the applied normal stress. We interpret these observations as wear mechanisms of (a) plowing into the fresh rock surfaces; (b) asperity breakage; and (c) asperity climb. The running-in stage is characterized by (1) intense wear-rate over a critical wear distance of Rd = 0.3-2 m; (2) drop of friction coefficient over a weakening distance of Dc = 0.2-4 m; (3) Rd and Dc display positive, quasi-linear relation with each other. We interpret these observations as indicating the organizing of newly-created wear particles into a 'three-body' structure that acts to lubricate the fault (Reches & Lockner, 2010). The steady

  6. Structure and evolution of barley powdery mildew effector candidates

    Directory of Open Access Journals (Sweden)

    Pedersen Carsten

    2012-12-01

    Full Text Available Abstract Background Protein effectors of pathogenicity are instrumental in modulating host immunity and disease resistance. The powdery mildew pathogen of grasses Blumeria graminis causes one of the most important diseases of cereal crops. B. graminis is an obligate biotrophic pathogen and as such has an absolute requirement to suppress or avoid host immunity if it is to survive and cause disease. Results Here we characterise a superfamily predicted to be the full complement of Candidates for Secreted Effector Proteins (CSEPs in the fungal barley powdery mildew parasite B. graminis f.sp. hordei. The 491 genes encoding these proteins constitute over 7% of this pathogen’s annotated genes and most were grouped into 72 families of up to 59 members. They were predominantly expressed in the intracellular feeding structures called haustoria, and proteins specifically associated with the haustoria were identified by large-scale mass spectrometry-based proteomics. There are two major types of effector families: one comprises shorter proteins (100–150 amino acids, with a high relative expression level in the haustoria and evidence of extensive diversifying selection between paralogs; the second type consists of longer proteins (300–400 amino acids, with lower levels of differential expression and evidence of purifying selection between paralogs. An analysis of the predicted protein structures underscores their overall similarity to known fungal effectors, but also highlights unexpected structural affinities to ribonucleases throughout the entire effector super-family. Candidate effector genes belonging to the same family are loosely clustered in the genome and are associated with repetitive DNA derived from retro-transposons. Conclusions We employed the full complement of genomic, transcriptomic and proteomic analyses as well as structural prediction methods to identify and characterize the members of the CSEPs superfamily in B. graminis f

  7. The Evolution of Community Structure in a Coauthorship Network

    Directory of Open Access Journals (Sweden)

    William Mcdowell

    2011-12-01

    Full Text Available Mechanisms such as triadic closure and preferential attachment drive the evolution of social networks. Many models use these mechanisms to predict future links, and they generate realistic networks with scale-free degree distributions. These social networks also have community structure, or sets of vertices which are more connected to each other than the rest of the network. To study the evolution of research groups of scientists in a coauthorship network, we use a timeheterarchy representation to extend the mechanisms driving the evolution of the network to the level of this community structure. Specifically, we examine changes in the structure of groups in terms of mechanisms analogous to triadic closure and preferential attachment, and as a result, we find that the network evolves in the same way at the group-level and the individual-level. In addition, we find that interactions at the group-level might affect interactions at the individual-level in that members of a single group are more likely to strengthen their relationships than members of separate groups.

  8. Analysis of snowpack properties and structure from TerraSAR-X data, based on multilayer backscattering and snow evolution modeling approaches

    CERN Document Server

    Phan, Xuan-Vu; Gay, Michel; Durand, Yves; Dumont, Marie; Allain, Sophie; D'Urso, Guy

    2012-01-01

    Recently launched high precision Synthetic Aperture Radar (SAR) satellites such as TerraSAR-X, COSMO-SkyMed, etc. present a high potential for better observation and characterization of the cryosphere. This study introduces a new approach using high frequency (X-band) SAR data and an Electromagnetic Backscattering Model (EBM) to constrain the detailed snowpack model Crocus. A snowpack EBM based on radiative transfer theory, previously used for C-band applications, is adapted for the X-band. From measured or simulated snowpack stratigraphic profiles consisting of snow optical grain radius and density, this forward model calculates the backscattering coefficient for different polarimetric channels. The output result is then compared with spaceborne TerraSAR-X acquisitions to evaluate the forward model. Next, from the EBM, the adjoint operator is developed and used in a variational analysis scheme in order to minimize the discrepancies between simulations and SAR observations. A time series of TerraSAR-X acquisi...

  9. Fine-structure constant variability surprises for laboratory atomic spectroscopy and cosmological evolution of quasar spectra

    CERN Document Server

    Bekenstein, J D

    2003-01-01

    Calculation of the Dirac hydrogen atom spectrum in the framework of dynamical fine structure constant (alpha) variability discloses a small departure in the laboratory from Sommerfeld's formula for the fine structure shifts, possibly measurable today. And for a distant object in the universe, the wavelength shift of a spectral line specifically ascribable to cosmological alpha variation is found to depend differently on the quantum numbers than in the conventional view. This last result clashes with the conventional wisdom that an atom's spectrum can change with cosmological time only through evolution of the alpha parameter in the energy eigenvalue formula, and thus impacts on the Webb group's analysis of fine structure intervals in quasar absorption lines (which has been claimed to disclose cosmological alpha evolution). In particular, analyzing together a mix of quasar absorption lines from different fine structure multiplets can bias estimates of cosmological alpha variability.

  10. Impact damage evolution under fatigue loading by InfraRed Thermography on composite structures

    Directory of Open Access Journals (Sweden)

    Pastor M.-L.

    2010-06-01

    Full Text Available This study deals with cumulative damage and its evolution in already impact damage composite structure. In order to follow the growing damage and to compare it with cumulative model, tests are monitored with an InfraRed thermography system. A carbon-epoxy composite is first low-energy impacted and then fatigued under tensioncompression loading. This study also enables a very fast analysis of predicting the damage evolution coupling InfraRed Thermography as NDT method and InfraRed thermography as a following system.

  11. Evol and ProDy for bridging protein sequence evolution and structural dynamics

    Science.gov (United States)

    Mao, Wenzhi; Liu, Ying; Chennubhotla, Chakra; Lezon, Timothy R.; Bahar, Ivet

    2014-01-01

    Correlations between sequence evolution and structural dynamics are of utmost importance in understanding the molecular mechanisms of function and their evolution. We have integrated Evol, a new package for fast and efficient comparative analysis of evolutionary patterns and conformational dynamics, into ProDy, a computational toolbox designed for inferring protein dynamics from experimental and theoretical data. Using information-theoretic approaches, Evol coanalyzes conservation and coevolution profiles extracted from multiple sequence alignments of protein families with their inferred dynamics. Availability and implementation: ProDy and Evol are open-source and freely available under MIT License from http://prody.csb.pitt.edu/. Contact: bahar@pitt.edu PMID:24849577

  12. Structural evolution and diversity of the caterpillar trunk

    DEFF Research Database (Denmark)

    Dupont, Steen Thorleif

    The thesis explores some major transformation series in the structure of the lepidopteran larval trunk, focusing partly on the initial events in the evolution of the order, partly on one of the more spectacular cases of subsequent biological diversification within ‘typical’/’higher’ Lepidoptera...... identify possible ground plan characteristics of the Lepidoptera and Amphiesmenoptera (MS1), 2) to describe and understand the evolution of the neolepidopteran caterpillar, and in particularly its crochet-bearing prolegs that are closely linked to walking on silken substrates and an external arboreal...... morphology in an attempt to link form and function (MS2-3). 4) to re-evaluate the previously indicated correlation between the cuticle thickness of lycaenid larvae and the degree of myrmecophily in a selection of species in this family, and through a comparative study to better understand the link between...

  13. Statistical Analysis of Hominoid Molecular Evolution

    OpenAIRE

    Barry, Daniel; Hartigan, J. A.

    1987-01-01

    The core data of molecular biology consists of DNA sequences. We will show how DNA sequences may be used to infer the evolution of the primates, human, chimpanzee, ape, orangutan and gibbon. The underlying probability models are taken to be Markov processes on trees. Some dependencies along the sequence due to the genetic code are also considered.

  14. Comparative Genome Analysis and Genome Evolution

    NARCIS (Netherlands)

    Snel, Berend

    2003-01-01

    This thesis described a collection of bioinformatic analyses on complete genome sequence data. We have studied the evolution of gene content and find that vertical inheritance dominates over horizontal gene trasnfer, even to the extent that we can use the gene content to make genome phylogenies. Usi

  15. A lithospheric perspective on structure and evolution of Precambrian cratons

    DEFF Research Database (Denmark)

    Artemieva, Irina

    2012-01-01

    The purpose of this chapter is to provide a summary of geophysical data on the structure of the stable continental lithosphere and its evolution since the Archean. Here, the term lithosphere is used to define the outer layer of the Earth which includes the crust and uppermost mantle, forms...... the roots of the continents, and moves together with continental plates. Depending on geophysical techniques (and physical properties measured), the lithosphere has different practical definitions. Most of them (i.e., seismic, electrical) are on the basis of a sharp change in temperature-dependent physical...

  16. Influence Activation Model: A New Perspective in Social Influence Analysis and Social Network Evolution

    CERN Document Server

    Yang, Yang; Lichtenwalter, Ryan N; Dong, Yuxiao

    2016-01-01

    What drives the propensity for the social network dynamics? Social influence is believed to drive both off-line and on-line human behavior, however it has not been considered as a driver of social network evolution. Our analysis suggest that, while the network structure affects the spread of influence in social networks, the network is in turn shaped by social influence activity (i.e., the process of social influence wherein one person's attitudes and behaviors affect another's). To that end, we develop a novel model of network evolution where the dynamics of network follow the mechanism of influence propagation, which are not captured by the existing network evolution models. Our experiments confirm the predictions of our model and demonstrate the important role that social influence can play in the process of network evolution. As well exploring the reason of social network evolution, different genres of social influence have been spotted having different effects on the network dynamics. These findings and ...

  17. Origin, Internal Structure and Evolution of 4 Vesta

    Science.gov (United States)

    Zuber, Maria T.; McSween, Harry Y.; Binzel, Richard P.; Elkins-Tanton, Linda T.; Konopliv, Alexander S.; Pieters, Carle M.; Smith, David E.

    2011-12-01

    Asteroid 4 Vesta is the only preserved intact example of a large, differentiated protoplanet like those believed to be the building blocks of terrestrial planet accretion. Vesta accreted rapidly from the solar nebula in the inner asteroid belt and likely melted due to heat released due to the decay of 26Al. Analyses of meteorites from the howardite-eucrite-diogenite (HED) suite, which have been both spectroscopically and dynamically linked to Vesta, lead to a model of the asteroid with a basaltic crust that overlies a depleted peridotitic mantle and an iron core. Vesta’s crust may become more mafic with depth and might have been intruded by plutons arising from mantle melting. Constraints on the asteroid’s moments of inertia from the long-wavelength gravity field, pole position and rotation, informed by bulk composition estimates, allow tradeoffs between mantle density and core size; cores of up to half the planetary radius can be consistent with plausible mantle compositions. The asteroid’s present surface is expected to consist of widespread volcanic terrain, modified extensively by impacts that exposed the underlying crust or possibly the mantle. Hemispheric heterogeneity has been observed by poorly resolved imaging of the surface that suggests the possibility of a physiographic dichotomy as occurs on other terrestrial planets. Vesta might have had an early magma ocean but details of the early thermal structure are far from clear owing to model uncertainties and paradoxical observations from the HEDs. Petrological analysis of the eucrites coupled with thermal evolution modeling recognizes two possible mechanisms of silicate-metal differentiation leading to the formation of the basaltic achondrites: equilibrium partial melting or crystallization of residual liquid from the cooling magma ocean. A firmer understanding the plethora of complex physical and chemical processes that contribute to melting and crystallization will ultimately be required to

  18. The structural and property evolution of cellulose during carbonization

    Science.gov (United States)

    Rhim, Yo-Rhin

    The understanding of the structure and related property evolution during carbonization is imperative in engineering carbon materials for specific functionalities. High purity cellulose was used as a model precursor to help understand the conversion of organic compounds to hard carbons. Several characterization techniques were employed to follow the structural, compositional and property changes during the thermal transformation of microcrystalline cellulose to carbon over the temperature range of 250°C to 2000°C. These studies revealed several stages of composition and microstructure evolution during carbonization supported by the observation of five distinct regions of electrical and thermal properties. In Region I, from 250°C to 400°C, depolymerisation of cellulose molecules caused the evolution of volatile gases and decrease in dipole polarization. This also led to the reduction of overall AC electrical conductivity and specific heat. In Region II, from 450°C to 500°C, the formation and growth of conducting sp 2 carbon clusters resulted in increases in overall AC electrical conductivity and thermal diffusivity with rising temperature. For heat treatment temperatures of 550°C and 600°C, Region III, carbon clusters grew into aggregates of curved carbon layers leading to interfacial polarization and onset of percolation. AC electrical and thermal conductivities are enhanced due to electron hopping and improved phonon transport among carbon clusters. With temperatures rising from 650°C to 1000°C, Region IV, DC conductivity began to emerge and increased sharply along with thermal conductivity with further percolation of carbon clusters as lateral growth of carbon layers continued. Lastly, from 1200°C to 2000°C, Region V, DC electrical conductivity remained constant due to a fully percolated system.

  19. Primary Cell Wall Structure in the Evolution of Land Plants

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Investigation of the primary cell walls of lower plants improves our understanding of the cell biology of these organisms but also has the potential to improve our understanding of cell wall structure and function in angiosperms that evolved from lower plants. Cell walls were prepared from eight species, ranging from a moss to advanced gymnosperms, and subjected to sequential chemical extraction to separate the main polysaccharide fractions. The glycosyl compositions of these fractions were then determined by gas chromatography. The results were compared among the eight plants and among data from related studies reported in the existing published reports to identify structural features that have been either highly conserved or clearly modified during evolution. Among the highly conserved features are the presence of a cellulose framework, the presence of certain hemicelluloses such as xyloglucan, and the presence of rhamnogalacturonan Ⅱ, a domain in pectic polysaccharides. Among the modified features are the abundance of mannosyl-containing hemicelluloses and the presence of methylated sugars.

  20. Convergent evolution of modularity in metabolic networks through different community structures

    Directory of Open Access Journals (Sweden)

    Zhou Wanding

    2012-09-01

    Full Text Available Abstract Background It has been reported that the modularity of metabolic networks of bacteria is closely related to the variability of their living habitats. However, given the dependency of the modularity score on the community structure, it remains unknown whether organisms achieve certain modularity via similar or different community structures. Results In this work, we studied the relationship between similarities in modularity scores and similarities in community structures of the metabolic networks of 1021 species. Both similarities are then compared against the genetic distances. We revisited the association between modularity and variability of the microbial living environments and extended the analysis to other aspects of their life style such as temperature and oxygen requirements. We also tested both topological and biological intuition of the community structures identified and investigated the extent of their conservation with respect to the taxomony. Conclusions We find that similar modularities are realized by different community structures. We find that such convergent evolution of modularity is closely associated with the number of (distinct enzymes in the organism’s metabolome, a consequence of different life styles of the species. We find that the order of modularity is the same as the order of the number of the enzymes under the classification based on the temperature preference but not on the oxygen requirement. Besides, inspection of modularity-based communities reveals that these communities are graph-theoretically meaningful yet not reflective of specific biological functions. From an evolutionary perspective, we find that the community structures are conserved only at the level of kingdoms. Our results call for more investigation into the interplay between evolution and modularity: how evolution shapes modularity, and how modularity affects evolution (mainly in terms of fitness and evolvability. Further, our results

  1. Wound Image Analysis Using Contour Evolution

    Directory of Open Access Journals (Sweden)

    K. Sundeep Kumar

    2014-05-01

    Full Text Available The aim of the algorithm described in this paper is to segment wound images from the normal and classify them according to the types of the wound. The segmentation of wounds extravagates color representation, which has been followed by an algorithm of grayscale segmentation based on the stack mathematical approach. Accurate classification of wounds and analyzing wound healing process is a critical task for patient care and health cost reduction at hospital. The tissue uniformity and flatness leads to a simplified approach but requires multispectral imaging for enhanced wound delineation. Contour Evolution method which uses multispectral imaging replaces more complex tools such as, SVM supervised classification, as no training step is required. In Contour Evolution, classification can be done by clustering color information, with differential quantization algorithm, the color centroids of small squares taken from segmented part of the wound image in (C1,C2 plane. Where C1, C2 are two chrominance components. Wound healing is identified by measuring the size of the wound through various means like contact and noncontact methods of wound. The wound tissues proportion is also estimated by a qualitative visual assessment based on the red-yellow-black code. Moreover, involving all the spectral response of the tissue and not only RGB components provides a higher discrimination for separating healed epithelial tissue from granulation tissue.

  2. Green chemistry and the evolution of flow analysis. A review.

    Science.gov (United States)

    Melchert, Wanessa R; Reis, Boaventura F; Rocha, Fábio R P

    2012-02-10

    Flow analysis has achieved its majority as a well-established tool to solve analytical problems. Evolution of flow-based approaches has been analyzed by diverse points of view, including historical aspects, the commutation concept and the impact on analytical methodologies. In this overview, the evolution of flow analysis towards green analytical chemistry is demonstrated by comparing classical procedures implemented with different flow approaches. The potential to minimize reagent consumption and waste generation and the ability to implement processes unreliable in batch to replace toxic chemicals are also emphasized. Successful applications of greener approaches in flow analysis are also discussed, focusing on the last 10 years. PMID:22244133

  3. Green chemistry and the evolution of flow analysis. A review.

    Science.gov (United States)

    Melchert, Wanessa R; Reis, Boaventura F; Rocha, Fábio R P

    2012-02-10

    Flow analysis has achieved its majority as a well-established tool to solve analytical problems. Evolution of flow-based approaches has been analyzed by diverse points of view, including historical aspects, the commutation concept and the impact on analytical methodologies. In this overview, the evolution of flow analysis towards green analytical chemistry is demonstrated by comparing classical procedures implemented with different flow approaches. The potential to minimize reagent consumption and waste generation and the ability to implement processes unreliable in batch to replace toxic chemicals are also emphasized. Successful applications of greener approaches in flow analysis are also discussed, focusing on the last 10 years.

  4. Astrocladistics: a phylogenetic analysis of galaxy evolution I. Character evolutions and galaxy histories

    CERN Document Server

    Fraix-Burnet, D; Douzery, E J P; Verhamme, A; Fraix-Burnet, Didier; Choler, Philippe; Douzery, Emmanuel J.P.; Verhamme, Anne

    2006-01-01

    This series of papers is intended to present astrocladistics in some detail and evaluate this methodology in reconstructing phylogenies of galaxies. Being based on the evolution of all the characters describing galaxies, it is an objective way of understanding galaxy diversity through evolutionary relationships. In this first paper, we present the basic steps of a cladistic analysis and show both theoretically and practically that it can be applied to galaxies. For illustration, we use a sample of 50 simulated galaxies taken from the GALICS database, which are described by 91 observables (dynamics, masses and luminosities). These 50 simulated galaxies are indeed 10 different galaxies taken at 5 cosmological epochs, and they are free of merger events. The astrocladistic analysis easily reconstructs the true chronology of evolution relationships within this sample. It also demonstrates that burst characters are not relevant for galaxy evolution as a whole. A companion paper is devoted to the formalization of th...

  5. Transverse zones controlling the structural evolution of the Zipaquira Anticline (Eastern Cordillera, Colombia): Regional implications

    Science.gov (United States)

    García, Helbert; Jiménez, Giovanny

    2016-08-01

    We report paleomagnetic, magnetic fabric and structural results from 21 sites collected in Cretaceous marine mudstones and Paleogene continental sandstones from the limbs, hinge and transverse zones of the Zipaquira Anticline (ZA). The ZA is an asymmetrical fold with one limb completely overturned by processes like gravity and salt tectonics, and marked by several axis curvatures. The ZA is controlled by at least two (2) transverse zones known as the Neusa and Zipaquira Transverse Zones (NTZ and ZTZ, respectively). Magnetic mineralogy methods were applied at different sites and the main carriers of the magnetic properties are paramagnetic components with some sites being controlled by hematite and magnetite. Magnetic fabric analysis shows rigid-body rotation for the back-limb in the ZA, while the forelimb is subjected to internal deformation. Structural and paleomagnetic data shows the influence of the NTZ and ZTZ in the evolution of the different structures like the ZA and the Zipaquira, Carupa, Rio Guandoque, Las Margaritas and Neusa faults, controlling several factors as vergence, extension, fold axis curvature and stratigraphic detatchment. Clockwise rotations unraveled a block segmentation following a discontinuos model caused by transverse zones and one site reported a counter clockwise rotation associated with a left-lateral strike slip component for transverse faults (e.g. the Neusa Fault). We propose that diverse transverse zones have been active since Paleogene times, playing an important role in the tectonic evolution of the Cundinamarca sub-basin and controlling the structural evolution of folds and faults with block segmentation and rotations.

  6. The Interior Structure, Composition, and Evolution of Giant Planets

    CERN Document Server

    Fortney, Jonathan J

    2009-01-01

    We discuss our current understanding of the interior structure and thermal evolution of giant planets. This includes the gas giants, such as Jupiter and Saturn, that are primarily composed of hydrogen and helium, as well as the "ice giants," such as Uranus and Neptune, which are primarily composed of elements heavier than H/He. The effect of different hydrogen equations of state (including new first-principles computations) on Jupiter's core mass and heavy element distribution is detailed. This variety of the hydrogen equations of state translate into an uncertainty in Jupiter's core mass of 18 M_Earth. For Uranus and Neptune we find deep envelope metallicities up to 0.95, perhaps indicating the existence of an eroded core, as also supported by their low luminosity. We discuss the results of simple cooling models of our solar system's planets, and show that more complex thermal evolution models may be necessary to understand their cooling history. We review how measurements of the masses and radii of the ~50 ...

  7. Structure and evolution of magnetic fields associated with solar eruptions

    International Nuclear Information System (INIS)

    This paper reviews the studies of solar photospheric magnetic field evolution in active regions and its relationship to solar flares. It is divided into two topics, the magnetic structure and evolution leading to solar eruptions and rapid changes in the photospheric magnetic field associated with eruptions. For the first topic, we describe the magnetic complexity, new flux emergence, flux cancelation, shear motions, sunspot rotation and magnetic helicity injection, which may all contribute to the storage and buildup of energy that trigger solar eruptions. For the second topic, we concentrate on the observations of rapid and irreversible changes of the photospheric magnetic field associated with flares, and the implication on the restructuring of the three-dimensional magnetic field. In particular, we emphasize the recent advances in observations of the photospheric magnetic field, as state-of-the-art observing facilities (such as Hinode and Solar Dynamics Observatory) have become available. The linkages between observations, theories and future prospectives in this research area are also discussed. (invited reviews)

  8. Cooling-induced structure formation and evolution in collapsars

    CERN Document Server

    Batta, Aldo

    2013-01-01

    The collapse of massive rotating stellar cores and the associated accretion onto the newborn compact object is thought to power long gamma ray bursts (GRBs). The physical scale and dynamics of the accretion disk are initially set by the angular momentum distribution in the progenitor, and the physical conditions make neutrino emission the main cooling agent in the flow. The formation and evolution of structure in these disks is potentially very relevant for the energy release and its time variability, which ultimately imprint on the observed GRB properties. To begin to characterize these, taking into account the three dimensional nature of the problem, we have carried out an initial set of calculations of the collapse of rotating polytropic cores in three dimensions, making use of a pseudo-relativistic potential and a simplified cooling prescription. We focus on the effects of self gravity and cooling on the overall morphology and evolution of the flow for a given rotation rate in the context of the collapsar...

  9. Structure and evolution of low-mass stars

    CERN Document Server

    Chabrier, G; Chabrier, Gilles; Baraffe, Isabelle

    1997-01-01

    We present extensive calculations of the structure and the evolution of low-massstars in the range 0.07-0.8 $\\msol$, for metallicities $-2.0\\le \\mh \\le 0.0$. These calculations are based on the most recent description of the microphysics characteristic of these dense and cool objects and on the lattest generation of grainless non-grey atmosphere models. We examine the evolution of the different mechanical and thermal properties of these objects as a function of mass and metallicity. We also demonstrate the inaccuracy of grey models and $T(\\tau)$ relationships under these conditions. We provide detailed tables of the mass-radius-luminosity-effective temperature relations for various ages and metallicities, aimed at calibrating existing or future observations of low-mass stars and massive brown dwarfs. We derive new hydrogen-burning minimum masses, within the afore-mentioned metallicity range. These minimum masses are found to be smaller than previous estimates, a direct consequence of non-grey effects. At last...

  10. Models of the Structure and Evolution of Protoplanetary Disks

    Science.gov (United States)

    Dullemond, C. P.; Hollenbach, D.; Kamp, I.; D'Alessio, P.

    We review advances in the modeling of protoplanetary disks. This review will focus on the regions of the disk beyond the dust sublimation radius, i.e., beyond 0.1-1 AU, depending on the stellar luminosity. We will be mostly concerned with models that aim to fit spectra of the dust continuum or gas lines, and derive physical parameters from these fits. For optically thick disks, these parameters include the accretion rate through the disk onto the star, the geometry of the disk, the dust properties, the surface chemistry, and the thermal balance of the gas. For the latter we are mostly concerned with the upper layers of the disk, where the gas and dust temperature decouple and a photoevaporative flow may originate. We also briefly discuss optically thin disks, focusing mainly on the gas, not the dust. The evolution of these disks is dominated by accretion, viscous spreading, photoevaporation, and dust settling and coagulation. The density and temperature structure arising from the surface layer models provide input to models of photoevaporation, which occurs largely in the outer disk. We discuss the consequences of photoevaporation on disk evolution and planet formation.

  11. Structures and their analysis

    CERN Document Server

    Fuchs, Maurice Bernard

    2016-01-01

    Addressing structures, this book presents a classic discipline in a modern setting by combining illustrated examples with insights into the solutions. It is the fruit of the author’s many years of teaching the subject and of just as many years of research into the design of optimal structures. Although intended for an advanced level of instruction it has an undergraduate course at its core. Further, the book was written with the advantage of having massive computer power in the background, an aspect which changes the entire approach to many engineering disciplines and in particular to structures. This paradigm shift has dislodged the force (flexibility) method from its former prominence and paved the way for the displacement (stiffness) method, despite the multitude of linear equations it spawns. In this book, however, both methods are taught: the force method offers a perfect vehicle for understanding structural behavior, bearing in mind that it is the displacement method which does the heavy number crunch...

  12. The evolution and revival structure of localized quantum wave packets

    CERN Document Server

    Bluhm, R; Porter, J; Bluhm, Robert; Kostelecky, Alan; Porter, James

    1995-01-01

    Localized quantum wave packets can be produced in a variety of physical systems and are the subject of much current research in atomic, molecular, chemical, and condensed-matter physics. They are particularly well suited for studying the classical limit of a quantum-mechanical system. The motion of a localized quantum wave packet initially follows the corresponding classical motion. However, in most cases the quantum wave packet spreads and undergoes a series of collapses and revivals. We present a generic treatment of wave-packet evolution, and we provide conditions under which various types of revivals occur in ideal form. The discussion is at a level appropriate for an advanced undergraduate or first-year graduate course in quantum mechanics. Explicit examples of different types of revival structure are provided, and physical applications are discussed.

  13. Evolution of Structural Damage in Aluminium Irradiated with Xenon Ions

    CERN Document Server

    Hofmann, A

    2001-01-01

    Structural defect evolution in high-purity aluminium both as-irradiated and annealed after irradiation has been investigated by transmission electron microscopy. The foils of high-purity aluminium were irradiated with 124 MeV Xe ions with fluence up to 2\\cdot 10^{16} Xe^+ cm^{-2} at room temperature and at 100 ^{o}C. The samples irradiated at 100 ^{o}C were annealed at 480 and 600 ^{o}C. At initial stage of irradiation, at low fluence (\\leq 2\\cdot 10^{14} Xe^+ cm^{-2}) the isolated dislocation loops are observed. When ion fluence increased the loops grow. At fluences above 10^{15} Xe^+ cm^{-2} cm the microstructure is characterized by high-density small voids (pores) which are grown and slowly merged with fluence increasing. For these conditions, the most possible mechanism of pore growth is their diffusion-controlled coalescence.

  14. Diversity, structure and convergent evolution of the global sponge microbiome.

    Science.gov (United States)

    Thomas, Torsten; Moitinho-Silva, Lucas; Lurgi, Miguel; Björk, Johannes R; Easson, Cole; Astudillo-García, Carmen; Olson, Julie B; Erwin, Patrick M; López-Legentil, Susanna; Luter, Heidi; Chaves-Fonnegra, Andia; Costa, Rodrigo; Schupp, Peter J; Steindler, Laura; Erpenbeck, Dirk; Gilbert, Jack; Knight, Rob; Ackermann, Gail; Victor Lopez, Jose; Taylor, Michael W; Thacker, Robert W; Montoya, Jose M; Hentschel, Ute; Webster, Nicole S

    2016-01-01

    Sponges (phylum Porifera) are early-diverging metazoa renowned for establishing complex microbial symbioses. Here we present a global Porifera microbiome survey, set out to establish the ecological and evolutionary drivers of these host-microbe interactions. We show that sponges are a reservoir of exceptional microbial diversity and major contributors to the total microbial diversity of the world's oceans. Little commonality in species composition or structure is evident across the phylum, although symbiont communities are characterized by specialists and generalists rather than opportunists. Core sponge microbiomes are stable and characterized by generalist symbionts exhibiting amensal and/or commensal interactions. Symbionts that are phylogenetically unique to sponges do not disproportionally contribute to the core microbiome, and host phylogeny impacts complexity rather than composition of the symbiont community. Our findings support a model of independent assembly and evolution in symbiont communities across the entire host phylum, with convergent forces resulting in analogous community organization and interactions. PMID:27306690

  15. Diversity, structure and convergent evolution of the global sponge microbiome

    Science.gov (United States)

    Thomas, Torsten; Moitinho-Silva, Lucas; Lurgi, Miguel; Björk, Johannes R.; Easson, Cole; Astudillo-García, Carmen; Olson, Julie B.; Erwin, Patrick M.; López-Legentil, Susanna; Luter, Heidi; Chaves-Fonnegra, Andia; Costa, Rodrigo; Schupp, Peter J.; Steindler, Laura; Erpenbeck, Dirk; Gilbert, Jack; Knight, Rob; Ackermann, Gail; Victor Lopez, Jose; Taylor, Michael W.; Thacker, Robert W.; Montoya, Jose M.; Hentschel, Ute; Webster, Nicole S.

    2016-01-01

    Sponges (phylum Porifera) are early-diverging metazoa renowned for establishing complex microbial symbioses. Here we present a global Porifera microbiome survey, set out to establish the ecological and evolutionary drivers of these host–microbe interactions. We show that sponges are a reservoir of exceptional microbial diversity and major contributors to the total microbial diversity of the world's oceans. Little commonality in species composition or structure is evident across the phylum, although symbiont communities are characterized by specialists and generalists rather than opportunists. Core sponge microbiomes are stable and characterized by generalist symbionts exhibiting amensal and/or commensal interactions. Symbionts that are phylogenetically unique to sponges do not disproportionally contribute to the core microbiome, and host phylogeny impacts complexity rather than composition of the symbiont community. Our findings support a model of independent assembly and evolution in symbiont communities across the entire host phylum, with convergent forces resulting in analogous community organization and interactions. PMID:27306690

  16. Structural Evolution and Mechanisms of Fatigue in Polycrystalline Brass

    DEFF Research Database (Denmark)

    Carstensen, Jesper Vejlø

    planar and wavy slip. The mechanical and structural behaviour observed in brass resembles recent observations in 316L austenitic stainless steels, and the present results reveal that Cu-30%Zn and 316L have approximately the same fatigue life curve. This empha-sizes brass as being a convenient model...... system for the industrially important austenitic steels. A quantitative fatigue damage characterization has been carried out using a classification of sur-face cracks based on their length and growth behaviour. This has provided the basis for using a numerical Monte Carlo type model, which has been...... further developed to account for the ob-served intergranular damage evolution on Cu-30%Zn. With these modifications the model pre-dicts the fatigue life curve of Cu-30%Zn and 316L....

  17. Biophysical and structural considerations for protein sequence evolution

    Directory of Open Access Journals (Sweden)

    Grahnen Johan A

    2011-12-01

    Full Text Available Abstract Background Protein sequence evolution is constrained by the biophysics of folding and function, causing interdependence between interacting sites in the sequence. However, current site-independent models of sequence evolutions do not take this into account. Recent attempts to integrate the influence of structure and biophysics into phylogenetic models via statistical/informational approaches have not resulted in expected improvements in model performance. This suggests that further innovations are needed for progress in this field. Results Here we develop a coarse-grained physics-based model of protein folding and binding function, and compare it to a popular informational model. We find that both models violate the assumption of the native sequence being close to a thermodynamic optimum, causing directional selection away from the native state. Sampling and simulation show that the physics-based model is more specific for fold-defining interactions that vary less among residue type. The informational model diffuses further in sequence space with fewer barriers and tends to provide less support for an invariant sites model, although amino acid substitutions are generally conservative. Both approaches produce sequences with natural features like dN/dS Conclusions Simple coarse-grained models of protein folding can describe some natural features of evolving proteins but are currently not accurate enough to use in evolutionary inference. This is partly due to improper packing of the hydrophobic core. We suggest possible improvements on the representation of structure, folding energy, and binding function, as regards both native and non-native conformations, and describe a large number of possible applications for such a model.

  18. The influence of halo evolution on galaxy structure

    Science.gov (United States)

    White, Simon

    2015-03-01

    If Einstein-Newton gravity holds on galactic and larger scales, then current observations demonstrate that the stars and interstellar gas of a typical bright galaxy account for only a few percent of its total nonlinear mass. Dark matter makes up the rest and cannot be faint stars or any other baryonic form because it was already present and decoupled from the radiation plasma at z = 1000, long before any nonlinear object formed. The weak gravito-sonic waves so precisely measured by CMB observations are detected again at z = 4 as order unity fluctuations in intergalactic matter. These subsequently collapse to form today's galaxy/halo systems, whose mean mass profiles can be accurately determined through gravitational lensing. High-resolution simulations link the observed dark matter structures seen at all these epochs, demonstrating that they are consistent and providing detailed predictions for all aspects of halo structure and growth. Requiring consistency with the abundance and clustering of real galaxies strongly constrains the galaxy-halo relation, both today and at high redshift. This results in detailed predictions for galaxy assembly histories and for the gravitational arena in which galaxies live. Dark halos are not expected to be passive or symmetric but to have a rich and continually evolving structure which will drive evolution in the central galaxy over its full life, exciting warps, spiral patterns and tidal arms, thickening disks, producing rings, bars and bulges. Their growth is closely related to the provision of new gas for galaxy building.

  19. 广东省旅游中心地规模等级结构变化趋势的分形分析%Fractal Analysis on the Scale Structure Evolution of Tourism Central Place in Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    许小卉

    2016-01-01

    In this paper we apply fractal theory to analyze the scale structure variation and the scale evo-lution trend for the tourism central places in Guangdong Province. By means of linear regression calculation, we obtain the Zipf dimensions and fractal dimensions of hierarchical structure of the tourism central places in Guangdong Province from 2005 to 2014. The results show that it is workable to apply the fractal theory to the scale structure of the tourism central places; the scale structure of the tourism central places in Guangdong Province conforms to Zipf law and possesses distinctively fractal feature;there appears several chasms in the hi-erarchical structure of the scale of the tourism central places; the monopoly of the first-rate tourism central place, Guangzhou gradually becomes weakened; the scale evolution trend for the tourism central places in Guangdong Province is getting smaller and smaller.%以广东省21个地级市为研究对象,运用分形理论,对广东省旅游中心地规模差异及其变化趋势进行研究。应用线性回归,得到广东省2005~2014年旅游中心地规模等级结构的Zipf维数和分形维数。结果表明,广东省旅游中心地规模结构符合Zipf法则并具有分形特征;旅游中心地规模的等级结构出现多次中间层次的断层;首位旅游中心地广州的垄断性逐渐减弱,旅游中心地规模差异具有逐渐减小的趋势。

  20. Markov chains or the game of structure and chance. From complex networks, to language evolution, to musical compositions

    Science.gov (United States)

    Blanchard, Ph.; Dawin, J. R.; Volchenkov, D.

    2010-06-01

    Markov chains provide us with a powerful tool for studying the structure of graphs and databases in details. We review the method of generalized inverses for Markov chains and apply it for the analysis of urban structures, evolution of languages, and musical compositions. We also discuss a generalization of Lévy flights over large complex networks and study the interplay between the nonlinearity of diffusion process and the topological structure of the network.

  1. Evolution Analysis of Simple Sequence Repeats in Plant Genome.

    Directory of Open Access Journals (Sweden)

    Zhen Qin

    Full Text Available Simple sequence repeats (SSRs are widespread units on genome sequences, and play many important roles in plants. In order to reveal the evolution of plant genomes, we investigated the evolutionary regularities of SSRs during the evolution of plant species and the plant kingdom by analysis of twelve sequenced plant genome sequences. First, in the twelve studied plant genomes, the main SSRs were those which contain repeats of 1-3 nucleotides combination. Second, in mononucleotide SSRs, the A/T percentage gradually increased along with the evolution of plants (except for P. patens. With the increase of SSRs repeat number the percentage of A/T in C. reinhardtii had no significant change, while the percentage of A/T in terrestrial plants species gradually declined. Third, in dinucleotide SSRs, the percentage of AT/TA increased along with the evolution of plant kingdom and the repeat number increased in terrestrial plants species. This trend was more obvious in dicotyledon than monocotyledon. The percentage of CG/GC showed the opposite pattern to the AT/TA. Forth, in trinucleotide SSRs, the percentages of combinations including two or three A/T were in a rising trend along with the evolution of plant kingdom; meanwhile with the increase of SSRs repeat number in plants species, different species chose different combinations as dominant SSRs. SSRs in C. reinhardtii, P. patens, Z. mays and A. thaliana showed their specific patterns related to evolutionary position or specific changes of genome sequences. The results showed that, SSRs not only had the general pattern in the evolution of plant kingdom, but also were associated with the evolution of the specific genome sequence. The study of the evolutionary regularities of SSRs provided new insights for the analysis of the plant genome evolution.

  2. Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Charlotte A.L.; Kavanagh, Christopher M. [School of Chemistry and EaStCHEM, University of St Andrews, St Andrews KY16 9ST (United Kingdom); Knight, Kevin S.; Kockelmann, Winfried [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Morrison, Finlay D. [School of Chemistry and EaStCHEM, University of St Andrews, St Andrews KY16 9ST (United Kingdom); Lightfoot, Philip, E-mail: pl@st-and.ac.uk [School of Chemistry and EaStCHEM, University of St Andrews, St Andrews KY16 9ST (United Kingdom)

    2015-10-15

    The thermal evolution of the crystal structure of the prototypical orthorhombic perovskite LaFeO{sub 3} has been studied in detail by powder neutron diffraction in the temperature range 25analysis, combined with an analysis in terms of symmetry-adapted modes, allows key aspects of the thermal behavior to be understood. In particular, the largest-amplitude symmetry modes (viz. in-phase and out-of-phase octahedral tilts, and A-site cation displacements) are shown to display relatively ‘normal’ behavior, increasing with decreasing temperature, which contrasts with the anomalous behavior previously shown by the derivative Bi{sub 0.5}La{sub 0.5}FeO{sub 3}. However, an unexpected behavior is seen in the nature of the intra-octahedral distortion, which is used to rationalize the unique occurrence of a temperature dependent crossover of the a and c unit cell metrics in this compound. - Graphical abstract: The unusual thermal evolution of lattice metrics in the perovskite LaFeO{sub 3} is rationalized from a detailed powder neutron diffraction study. - Highlights: • Crystal structure of the perovskite LaFeO{sub 3} studied in detail by powder neutron diffraction. • Unusual thermal evolution of lattice metrics rationalized. • Contrasting behavior to Bi-doped LaFeO{sub 3}. • Octahedral distortion/tilt parameters explain unusual a and c lattice parameter behavior.

  3. Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO3

    International Nuclear Information System (INIS)

    The thermal evolution of the crystal structure of the prototypical orthorhombic perovskite LaFeO3 has been studied in detail by powder neutron diffraction in the temperature range 25analysis, combined with an analysis in terms of symmetry-adapted modes, allows key aspects of the thermal behavior to be understood. In particular, the largest-amplitude symmetry modes (viz. in-phase and out-of-phase octahedral tilts, and A-site cation displacements) are shown to display relatively ‘normal’ behavior, increasing with decreasing temperature, which contrasts with the anomalous behavior previously shown by the derivative Bi0.5La0.5FeO3. However, an unexpected behavior is seen in the nature of the intra-octahedral distortion, which is used to rationalize the unique occurrence of a temperature dependent crossover of the a and c unit cell metrics in this compound. - Graphical abstract: The unusual thermal evolution of lattice metrics in the perovskite LaFeO3 is rationalized from a detailed powder neutron diffraction study. - Highlights: • Crystal structure of the perovskite LaFeO3 studied in detail by powder neutron diffraction. • Unusual thermal evolution of lattice metrics rationalized. • Contrasting behavior to Bi-doped LaFeO3. • Octahedral distortion/tilt parameters explain unusual a and c lattice parameter behavior

  4. Computational Analysis for Morphological Evolution in Pyrolysis for Micro/Nanofabrication

    OpenAIRE

    Yang, Myeongseok; Lee, Wooju; Shin, Heungjoo; Kim, Dongchoul

    2015-01-01

    Pyrolysis is recently proposed as an efficient fabrication technique of micro/nanoscale carbon structures. In order to understand the morphological evolution in pyrolysis and design the final shape of carbon structure, this study proposes a comprehensive model that incorporates the essential mechanisms of pyrolysis based on the phase field framework. Computational analysis with the developed model provides information about the effect of interface energy and kinetic rate on the morphological ...

  5. 基于概率密度演化的渡槽结构抗震分析%Seismic Analysis of Large-scale Aqueduct Structures Based on the Probability Density Evolution Method

    Institute of Scientific and Technical Information of China (English)

    曾波; 邢彦富; 刘章军

    2014-01-01

    Using the orthogonal expansion method of random processes,the non-stationary seismic acceleration process is represented as a linear combination of the standard orthogonal basis func-tions and the standard orthogonal random variables.Then,using the random function,these stand-ard orthogonal random variables in the orthogonal expansion are expressed as an orthogonal func-tion form of the basic random variable.Therefore,this method can use a basic random variable to express the original earthquake ground processes.The orthogonal expansion-random function ap-proach was used to generate 126 representative earthquake samples,and each representative sam-ple was assigned a given probability.The 126 representative earthquake samples were combined with the probability density evolution method of stochastic dynamical systems and random seis-mic responses of large-scale aqueduct structures was investigated.In this study,four cases were considered;aqueduct without water,aqueduct with water in the central trough,aqueduct with wa-ter in a two-side trough,and aqueduct with water in three troughs,and probability information of seismic responses for these cases were obtained.Moreover,using the proposed method,the seis-mic reliability of the aqueduct structures was efficiently calculated.This method provides a new and effective means for precise seismic analysis of large-scale aqueduct structures.%应用随机过程的正交展开方法,将地震动加速度过程展开为标准正交基函数与标准正交随机变量的线性组合形式。在此基础上采用随机函数的思想,将正交展开式中的标准正交随机变量表达为基本随机变量的函数形式,从而实现用一个基本随机变量来表达原地震动过程的目的。结合地震动过程的正交展开-随机函数模型与概率密度演化方法,对某大型渡槽结构进行随机地震反应分析与抗震可靠度计算;重点研究空槽和三槽有水等四种工况下渡槽结构

  6. Cenozoic structures and the tectonic evolution of the eastern North Sea

    DEFF Research Database (Denmark)

    Clausen, O.R.; Nielsen, S.B.; Egholm, D.L.;

    2011-01-01

    of relaxation inversion (Nielsen et al. 2005). In conclusion, the Cenozoic structures in the North Sea area do not generally support ideas on Neogene basement tectonism. References: Clausen, O. R. and M. Huuse (1999). "Topography of the Top Chalk surface on- and offshore Denmark." Marine and Petroleum Geology......Abundant seismic sections and well data from the Cenozoic succession in the eastern North Sea area generally reveal normal faulting, salt tectonics and localized tectonic inversion. However, inferences on the Cenozoic dynamic evolution of the region require thorough analysis of interactions between...... detachment surfaces withinthe sedimentary succession and basement structures. Here we define basement structures by offsets in the pre Zechstein succession. Cover structures are confined to the post Zechstein succession, or part hereof, and detach internally along surfaces in the post Zechstein succession...

  7. Orchestrated structure evolution: modeling growth-regulated nanomanufacturing

    Science.gov (United States)

    Abbasi, Shaghayegh; Kitayaporn, Sathana; Schwartz, Daniel T.; Böhringer, Karl F.

    2011-04-01

    Orchestrated structure evolution (OSE) is a scalable manufacturing method that combines the advantages of top-down (tool-directed) and bottom-up (self-propagating) approaches. The method consists of a seed patterning step that defines where material nucleates, followed by a growth step that merges seeded islands into the final patterned thin film. We develop a model to predict the completed pattern based on a computationally efficient approximate Green's function solution of the diffusion equation plus a Voronoi diagram based approach that defines the final grain boundary structure. Experimental results rely on electron beam lithography to pattern the seeds, followed by the mass transfer limited growth of copper via electrodeposition. The seed growth model is compared with experimental results to quantify nearest neighbor seed-to-seed interactions as well as how seeds interact with the pattern boundary to impact the local growth rate. Seed-to-seed and seed-to-pattern interactions are shown to result in overgrowth of seeds on edges and corners of the shape, where seeds have fewer neighbors. We explore how local changes to the seed location can be used to improve the patterning quality without increasing the manufacturing cost. OSE is shown to enable a unique set of trade-offs between the cost, time, and quality of thin film patterning.

  8. Structural Evolution of Household Energy Consumption: A China Study

    Directory of Open Access Journals (Sweden)

    Qingsong Wang

    2015-04-01

    Full Text Available Sustainable energy production and consumption is one of the issues for the sustainable development strategy in China. As China’s economic development paradigm shifts, household energy consumption (HEC has become a focus of achieving national goals of energy efficiency and greenhouse gas reduction. The information entropy model and LMDI model were employed in this study in order to analyse the structural evolution of HEC, as well as its associated critical factors. The results indicate that the information entropy of HEC increased gradually, and coal will be reduced by clean energies, such as natural gas and liquefied petroleum gas. The information entropy tends to stabilize and converge due to rapid urbanization. Therefore, from the perspective of environmental protection and natural resource conservation, the structure of household energy consumption will be optimized. This study revealed that residents’ income level is one of the most critical factors for the increase of energy consumption, while the energy intensity is the only driving force for the reduction of HEC. The accumulated contribution of these two factors to the HEC is 240.53% and −161.75%, respectively. It is imperative to improve the energy efficiency in the residential sector. Recommendations are provided to improve the energy efficiency-related technologies, as well as the standards for the sustainable energy strategy.

  9. Shell structure evolution far from stability: experimental results

    International Nuclear Information System (INIS)

    Shell structure evolution in nuclei situated at the extremes of neutron and proton excess are investigated using in-beam gamma spectroscopy techniques with radioactive beams at GANIL. A selection of results obtained very recently is presented: i) The reduced transition probabilities B(E2;0+1 → 2+) of the neutron-rich 74Zn and 70Ni nuclei have been measured using Coulomb excitation at intermediate energy. An unexpected large proton core polarization has been found in 70Ni and interpreted as being due to the monopole interaction between the neutron g9/2 and protons f7/2 and f5/2 spin-orbit partner orbitals. ii) Two proton knock-out reactions has been performed in order to study the most neutron-rich nuclei at the N = 28 shell closure. Gamma rays spectra and momentum distribution have been obtained for 42Si and neighboring nuclei. Evidence has been found for a deformed structure at N = 28 for Silicon, despite a relatively large Z = 14 gap. iii) The in-beam gamma spectroscopy of 36Ca performed using neutron knock-out reactions revealed that N = 16 is as large sub-shell closure as Z = 16 in 36S. The uniquely large excitation energy difference of the first 2+ state in these mirror nuclei turns out to be a consequence of their relatively pure neutron or proton 1p(d3/2)-1h(s1/2) nature

  10. Functional role, structure, and evolution of the melanocortin-4 receptor.

    Science.gov (United States)

    Schiöth, Helgi B; Lagerström, Malin C; Watanobe, Hajime; Jonsson, Logi; Vergoni, Anna Valeria; Ringholm, Aneta; Skarphedinsson, Jon O; Skuladottir, Gudrun V; Klovins, Janis; Fredriksson, Robert

    2003-06-01

    The melanocortin (MC)-4 receptor participates in regulating body weight homeostasis. We demonstrated early that acute blockage of the MC-4 receptor increases food intake and relieves anorexic conditions in rats. Our recent studies show that 4-week chronic blockage of the MC-4 receptor leads to robust increases in food intake and development of obesity, whereas stimulation of the receptor leads to anorexia. Interestingly, the food conversion ratio was clearly increased by MC-4 receptor blockage, whereas it was decreased in agonist-treated rats in a transient manner. Chronic infusion of an agonist caused a transient increase in oxygen consumption. Our studies also show that the MC-4 receptor plays a role in luteinizing hormone and prolactin surges in female rats. The MC-4 receptor has a role in mediating the effects of leptin on these surges. The phylogenetic relation of the MC-4 receptor to other GPCRs in the human genome was determined. The three-dimensional structure of the protein was studied by construction of a high-affinity zinc binding site between the helices, using two histidine residues facing each other. We also cloned the MC-4 receptor from evolutionary important species and showed by chromosomal mapping a conserved synteny between humans and zebrafish. The MC-4 receptor has been remarkably conserved in structure and pharmacology for more than 400 million years, implying that the receptor participated in vital physiological functions early in vertebrate evolution. PMID:12851300

  11. Structural evolution mechanisms of amorphous and liquid As2Se3 at high pressures

    Science.gov (United States)

    Properzi, L.; Santoro, M.; Minicucci, M.; Iesari, F.; Ciambezi, M.; Nataf, L.; Le Godec, Y.; Irifune, T.; Baudelet, F.; Di Cicco, A.

    2016-06-01

    The elusive structure of compressed, melt-quenched As2Se3 was studied in both its liquid and amorphous form up to 4.4 and 30 GPa, respectively, by means of x-ray absorption spectroscopy and diffraction. The evolution of the short-range structure is studied by As and Se multiple K -edge extended x-ray absorption fine structure (EXAFS) refinement, while changes in intermediate-range ordering are revealed by x-ray diffraction and near-edge structures. In the liquid, at the nearest-neighbor length scales, a gradual disordering and slight elongation of the As-Se average distances is observed, preserving the local coordination upon increasing pressure, whereas substantial compression and disordering are observed at intermediate distances. Similarly, in the amorphous form we found a progressive slight elongation and disordering of the first-neighbor As-Se average distance R (from ˜2.42 to 2.44 Å) and bond variance σ2 (from ˜0.004 to 0.008 Å2) upon increasing pressures up to 30 GPa. On the other hand, gradual shortening of the second and farther neighbor distances, more evident below 15 GPa, are compatible with data analysis. No sign of crystallization and gradual metallization are observed for amorphous a-As2Se3 up to 30 GPa. The emerging picture for the structure evolution under high pressures is a compaction mechanism involving mainly changes at intermediate distances, weakly affecting the first-neighbor bonding character.

  12. Structured Analysis - IDEF0

    DEFF Research Database (Denmark)

    Larsen, Michael Holm

    1999-01-01

    This note introduces the IDEF0 modelling language (semantics and syntax), and associated rules and techniques, for developing structured graphical representations of a system or enterprise. Use of this standard for IDEF0 permits the construction of models comprising system functions (activities......, actions, processes, operations), functional relationships, and data (information or objects) that support systems integration. An IDEF0 model is domain specific in the sense that purpose, viewpoint and context must be identified in the model. The IDEF0 modelling language is recommended for projects...... for Integration Definition for Function Modelling (IDEF0). I.e. the Draft Federal Information Processing Standards Publication 183, 1993, December 21, Announcing the Standard for Integration Definition for Function Modelling (IDEF0)....

  13. Coda Wave Interferometry Method Applied in Structural Monitoring to Assess Damage Evolution in Masonry and Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Masera, D; Bocca, P; Grazzini, A, E-mail: davide.masera@polito.it [Department of Structural and Geotechnical Engineering - Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Turin (Italy)

    2011-07-19

    In this experimental program the main goal is to monitor the damage evolution in masonry and concrete structures by Acoustic Emission (AE) signal analysis applying a well-know seismic method. For this reason the concept of the coda wave interferometry is applied to AE signal recorded during the tests. Acoustic Emission (AE) are very effective non-destructive techniques applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate the velocity of ultrasound waves propagation and the amount of energy released during fracture propagation to obtain information on the criticality of the ongoing process. By means of AE monitoring, an experimental analysis on a set of reinforced masonry walls under variable amplitude loading and strengthening reinforced concrete (RC) beams under monotonic static load has been carried out. In the reinforced masonry wall, cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of masonry under static long-time loading. During the tests, the evaluation of fracture growth is monitored by coda wave interferometry which represents a novel approach in structural monitoring based on AE relative change velocity of coda signal. In general, the sensitivity of coda waves has been used to estimate velocity changes in fault zones, in volcanoes, in a mining environment, and in ultrasound experiments. This method uses multiple scattered waves, which travelled through the material along numerous paths, to infer tiny temporal changes in the wave velocity. The applied method has the potential to be used as a 'damage-gauge' for monitoring velocity changes as a sign of damage evolution into masonry and concrete structures.

  14. Coda Wave Interferometry Method Applied in Structural Monitoring to Assess Damage Evolution in Masonry and Concrete Structures

    Science.gov (United States)

    Masera, D.; Bocca, P.; Grazzini, A.

    2011-07-01

    In this experimental program the main goal is to monitor the damage evolution in masonry and concrete structures by Acoustic Emission (AE) signal analysis applying a well-know seismic method. For this reason the concept of the coda wave interferometry is applied to AE signal recorded during the tests. Acoustic Emission (AE) are very effective non-destructive techniques applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate the velocity of ultrasound waves propagation and the amount of energy released during fracture propagation to obtain information on the criticality of the ongoing process. By means of AE monitoring, an experimental analysis on a set of reinforced masonry walls under variable amplitude loading and strengthening reinforced concrete (RC) beams under monotonic static load has been carried out. In the reinforced masonry wall, cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of masonry under static long-time loading. During the tests, the evaluation of fracture growth is monitored by coda wave interferometry which represents a novel approach in structural monitoring based on AE relative change velocity of coda signal. In general, the sensitivity of coda waves has been used to estimate velocity changes in fault zones, in volcanoes, in a mining environment, and in ultrasound experiments. This method uses multiple scattered waves, which travelled through the material along numerous paths, to infer tiny temporal changes in the wave velocity. The applied method has the potential to be used as a "damage-gauge" for monitoring velocity changes as a sign of damage evolution into masonry and concrete structures.

  15. Microeconomic co-evolution model for financial technical analysis signals

    CERN Document Server

    Rotundo, G

    2006-01-01

    Technical analysis (TA) has been used for a long time before the availability of more sophisticated instruments for financial forecasting in order to suggest decisions on the basis of the occurrence of data patterns. Many mathematical and statistical tools for quantitative analysis of financial markets have experienced a fast and wide growth and have the power for overcoming classical technical analysis methods. This paper aims to give a measure of the reliability of some information used in TA by exploring the probability of their occurrence within a particular $microeconomic$ agent based model of markets, i.e., the co-evolution Bak-Sneppen model originally invented for describing species population evolutions. After having proved the practical interest of such a model in describing financial index so called avalanches, in the prebursting bubble time rise, the attention focuses on the occurrence of trend line detection crossing of meaningful barriers, those that give rise to some usual technical analysis str...

  16. The Geography, Structure and Evolution of Infrastructure Networks in Europe

    OpenAIRE

    Vinciguerra, S.

    2012-01-01

    In recent years, network science has entered in virtually every scientific discipline. Some even speak of the “new science of networks” causing a scientific revolution across all disciplines. Also in Geography and Urban Studies, interest in network analysis has increased. This interest is understandable since most networks have a geographical structure, with nodes being located in space and links providing connections across space. This study positions itself at the interface of Social Networ...

  17. Evolution of a defect structure of Pd-Ag alloys during tritium exposure

    Energy Technology Data Exchange (ETDEWEB)

    Tebus, V. E-mail: tebus@bochvar.ru; Rivkis, L.; Dmitrievskaia, E.; Arutunova, G.; Golikov, I.; Ryazantseva, N.; Filin, V.; Kapychev, V.; Bulkin, V

    2002-12-01

    Pd-Ag alloys, a material for palladium diffuser of the ITER fuel clean-up system, were investigated after long-term usage exposition in tritium. Nucleation and evolution of the alloy structure defects as a result of a radiogenic helium-3 accumulation have been examined using electron microscopy, positron annihilation and X-ray analysis. The types of helium containing defects and their characteristics were determined. The early stage of helium bubbles forming was observed. It was shown that the simple defect concentration decreased slowly and helium-3 bubble sizes and concentration increased during the tritium exposure.

  18. Boltzmann, Lotka and Volterra and spatial structural evolution: an integrated methodology for some dynamical systems.

    Science.gov (United States)

    Wilson, Alan

    2008-08-01

    It is shown that Boltzmann's methods from statistical physics can be applied to a much wider range of systems, and in a variety of disciplines, than has been commonly recognized. A similar argument can be applied to the ecological models of Lotka and Volterra. Furthermore, it is shown that the two methodologies can be applied in combination to generate the Boltzmann, Lotka and Volterra (BLV) models. These techniques enable both spatial interaction and spatial structural evolution to be modelled, and it is argued that they potentially provide a much richer modelling methodology than that currently used in the analysis of 'scale-free' networks.

  19. Comparative Analysis of the Value Added Tax Evolution

    Directory of Open Access Journals (Sweden)

    Mirela Anca Postole

    2013-06-01

    Full Text Available The impact of indirect taxes is analysed in the study of evolution, especially the VAT for the economic activity of the company studied. During the reporting period, namely January 2009 – December 2011 the supporting documents were checked which records on VAT deductible and collected were based on, in compliance with legal norms and principles of financial accounting. Also the data processed were the basis for an analysis to compare the evolution of VAT. VAT shall be paid for the entire activity of the company.

  20. Evolution of grain structures during directional solidification of silicon wafers

    Science.gov (United States)

    Lin, H. K.; Wu, M. C.; Chen, C. C.; Lan, C. W.

    2016-04-01

    The evolution of grain structures, especially the types of grain boundaries (GBs), during directional solidification is crucial to the electrical properties of multicrystalline silicon used for solar cells. To study this, the electric molten zone crystallization (EMZC) of silicon wafers at different drift speeds from 2 to 6 mm/min was considered. It was found that orientation was dominant at the lower drift velocity, while orientation at the higher drift velocity. Most of the non-∑GBs tended to align with the thermal gradient, but some tilted toward the unfavorable grains having higher interfacial energies. On the other hand, the tilted ∑3GBs tended to decrease during grain competition, except at the higher speed, where the twin nucleation became frequent. The competition of grains separated by ∑GBs could be viewed as the interactions of GBs that two coherent ∑3n GBs turned into one ∑3nGB following certain relations as reported before. On the other hand, when ∑ GBs met non-∑ GBs, the non-∑ GBs remained which explained the decrease of ∑ GBs at the lower speed.

  1. Interactive diversity promotes the evolution of cooperation in structured populations

    Science.gov (United States)

    Su, Qi; Li, Aming; Zhou, Lei; Wang, Long

    2016-10-01

    Evolutionary games on networks traditionally assume that each individual adopts an identical strategy to interact with all its neighbors in each generation. Considering the prevalent diversity of individual interactions in the real society, here we propose the concept of interactive diversity, which allows individuals to adopt different strategies against different neighbors in each generation. We investigate the evolution of cooperation based on the edge dynamics rather than the traditional nodal dynamics in networked systems. The results show that, without invoking any other mechanisms, interactive diversity drives the frequency of cooperation to a high level for a wide range of parameters in both well-mixed and structured populations. Even in highly connected populations, cooperation still thrives. When interactive diversity and large topological heterogeneity are combined together, however, in the relaxed social dilemma, cooperation level is lower than that with just one of them, implying that the combination of many promotive factors may make a worse outcome. By an analytical approximation, we get the condition under which interactive diversity provides more advantages for cooperation than traditional evolutionary dynamics does. Numerical simulations validating the approximation are also presented. Our work provides a new line to explore the latent relation between the ubiquitous cooperation and individuals’ distinct responses in different interactions. The presented results suggest that interactive diversity should receive more attention in pursuing mechanisms fostering cooperation.

  2. Mutation rates and the evolution of germline structure.

    Science.gov (United States)

    Scally, Aylwyn

    2016-07-19

    Genome sequencing studies of de novo mutations in humans have revealed surprising incongruities in our understanding of human germline mutation. In particular, the mutation rate observed in modern humans is substantially lower than that estimated from calibration against the fossil record, and the paternal age effect in mutations transmitted to offspring is much weaker than expected from our long-standing model of spermatogenesis. I consider possible explanations for these discrepancies, including evolutionary changes in life-history parameters such as generation time and the age of puberty, a possible contribution from undetected post-zygotic mutations early in embryo development, and changes in cellular mutation processes at different stages of the germline. I suggest a revised model of stem-cell state transitions during spermatogenesis, in which 'dark' gonial stem cells play a more active role than hitherto envisaged, with a long cycle time undetected in experimental observations. More generally, I argue that the mutation rate and its evolution depend intimately on the structure of the germline in humans and other primates.This article is part of the themed issue 'Dating species divergences using rocks and clocks'. PMID:27325834

  3. The structure and evolution of buyer-supplier networks.

    Science.gov (United States)

    Mizuno, Takayuki; Souma, Wataru; Watanabe, Tsutomu

    2014-01-01

    In this paper, we investigate the structure and evolution of customer-supplier networks in Japan using a unique dataset that contains information on customer and supplier linkages for more than 500,000 incorporated non-financial firms for the five years from 2008 to 2012. We find, first, that the number of customer links is unequal across firms; the customer link distribution has a power-law tail with an exponent of unity (i.e., it follows Zipf's law). We interpret this as implying that competition among firms to acquire new customers yields winners with a large number of customers, as well as losers with fewer customers. We also show that the shortest path length for any pair of firms is, on average, 4.3 links. Second, we find that link switching is relatively rare. Our estimates indicate that the survival rate per year for customer links is 92 percent and for supplier links 93 percent. Third and finally, we find that firm growth rates tend to be more highly correlated the closer two firms are to each other in a customer-supplier network (i.e., the smaller is the shortest path length for the two firms). This suggests that a non-negligible portion of fluctuations in firm growth stems from the propagation of microeconomic shocks - shocks affecting only a particular firm - through customer-supplier chains. PMID:25000368

  4. Structure Shape Evolution in Lanthanide and Actinide Nuclei

    Directory of Open Access Journals (Sweden)

    Khalaf A. M.

    2013-04-01

    Full Text Available To give the characteristics of the evolution of the collectivity in even-even nuclei, we studied the behavior of the energy ratios R(4 / 2 and R(6 / 4. All chains of lanthanides begins as vibrational with R(4 / 2 near 2.0 and move towards rotational (R(4 / 2 3.33 as neutron number increases. A rabid jump in R(4 / 2 near N = 90 was seen. The plot of R(4 / 2 against Z shows not only the existence of a shape transitions but also the change in curvature in the data for N = 88 and 90, concave to convex. For intermedi- ate structure the slopes in E-GOS ( E over spin plots range between the vibrator and rotor extremes. The abnormal behavior of the two-neutron separation energies of our lanthanide nuclei as a function of neutron number around neutron number 90 is cal- culated. Nonlinear behavior is observed which indicate that shape phase transition is occurred in this region. The calculated reduced B(E2 transition probabilities of the low states of the ground state band in the nuclei 150 Nd / 152 Sm / 154 Gd / 156 Dy are analyzed and compared to the prediction of vibrational U(5 and rotational SU(3 limits of interacting boson model calculations.

  5. The structure and evolution of buyer-supplier networks.

    Directory of Open Access Journals (Sweden)

    Takayuki Mizuno

    Full Text Available In this paper, we investigate the structure and evolution of customer-supplier networks in Japan using a unique dataset that contains information on customer and supplier linkages for more than 500,000 incorporated non-financial firms for the five years from 2008 to 2012. We find, first, that the number of customer links is unequal across firms; the customer link distribution has a power-law tail with an exponent of unity (i.e., it follows Zipf's law. We interpret this as implying that competition among firms to acquire new customers yields winners with a large number of customers, as well as losers with fewer customers. We also show that the shortest path length for any pair of firms is, on average, 4.3 links. Second, we find that link switching is relatively rare. Our estimates indicate that the survival rate per year for customer links is 92 percent and for supplier links 93 percent. Third and finally, we find that firm growth rates tend to be more highly correlated the closer two firms are to each other in a customer-supplier network (i.e., the smaller is the shortest path length for the two firms. This suggests that a non-negligible portion of fluctuations in firm growth stems from the propagation of microeconomic shocks - shocks affecting only a particular firm - through customer-supplier chains.

  6. Models of the Structure and Evolution of Protoplanetary Disks

    CERN Document Server

    Dullemond, C P; Kamp, I; D'Alessio, P

    2006-01-01

    We review advances in the modeling of protoplanetary disks. This review will focus on the regions of the disk beyond the dust sublimation radius, i.e. beyond 0.1 - 1 AU, depending on the stellar luminosity. We will be mostly concerned with models that aim to fit spectra of the dust continuum or gas lines, and derive physical parameters from these fits. For optically thick disks, these parameters include the accretion rate through the disk onto the star, the geometry of the disk, the dust properties, the surface chemistry and the thermal balance of the gas. For the latter we are mostly concerned with the upper layers of the disk, where the gas and dust temperature decouple and a photoevaporative flow may originate. We also briefly discuss optically thin disks, focusing mainly on the gas, not the dust. The evolution of these disks is dominated by accretion, viscous spreading, photoevaporation, and dust settling and coagulation. The density and temperature structure arising from the surface layer models provide ...

  7. Structure and evolution of the global seafood trade network

    Science.gov (United States)

    Gephart, Jessica A.; Pace, Michael L.

    2015-12-01

    The food production system is increasingly global and seafood is among the most highly traded commodities. Global trade can improve food security by providing access to a greater variety of foods, increasing wealth, buffering against local supply shocks, and benefit the environment by increasing overall use efficiency for some resources. However, global trade can also expose countries to external supply shocks and degrade the environment by increasing resource demand and loosening feedbacks between consumers and the impacts of food production. As a result, changes in global food trade can have important implications for both food security and the environmental impacts of production. Measurements of globalization and the environmental impacts of food production require data on both total trade and the origin and destination of traded goods (the network structure). While the global trade network of agricultural and livestock products has previously been studied, seafood products have been excluded. This study describes the structure and evolution of the global seafood trade network, including metrics quantifying the globalization of seafood, shifts in bilateral trade flows, changes in centrality and comparisons of seafood to agricultural and industrial trade networks. From 1994 to 2012 the number of countries trading in the network remained relatively constant, while the number of trade partnerships increased by over 65%. Over this same period, the total quantity of seafood traded increased by 58% and the value increased 85% in real terms. These changes signify the increasing globalization of seafood products. Additionally, the trade patterns in the network indicate: increased influence of Thailand and China, strengthened intraregional trade, and increased exports from South America and Asia. In addition to characterizing these network changes, this study identifies data needs in order to connect seafood trade with environmental impacts and food security outcomes.

  8. Structural evolution and mechanisms of fatigue in polycrystalline brass

    Energy Technology Data Exchange (ETDEWEB)

    Vejloe Carstensen, J

    1998-03-01

    The plastic strain controlled fatigue behaviour of polycrystalline Cu-15%Zn and Cu-30%Zn has been investigated with the aim of studying the effect of slip mode modification by the addition of zinc to copper. It has been clearly demonstrated, that true cyclic saturation does not occur in the plastic strain controlled fatigue of brass. This complicates the contstruction of a cyclic stress-strain (CSS) curve and thus the comparison with copper. A method to overcome this complication has been suggested. Surface observations on fatigued brass specimens show that individual grains tend to deform by Sachs type single slip. This behaviour has been described by the self-consistent Sachs-Eshelby model, which provides estimates of the CSS curve for brass polycrystals. Successive stages of primary hardening, softening and secondary hardening has been observed in the plastic strain controlled fatigue of brass. It has been found that the primary hardening is attributed to an increase of intergranular stresses whereas the secondary hardening apparently is attributed to an increase of friction stresses. Investigations of the structural evolution show that the softening behaviour can be explained by the presence of short-range order (SRO). SRO promote the formation of extended dipole arrays which hardens the material. The formation of intense shear bands destroy the dipole arrays, which explains the cyclic softening. The present results reveal that Cu-30%Zn in a pure planar slip alloy, while Cu-15%Zn displays both planar and wavy slip. The mechanical and structural behaviour observed in brass resembles recent observations in 316L austenitic stainless steels, and the present results reveal that Cu-30%Zn and 316L have approximately the same fatigue life curve. This emphasizes brass as being a convenient model system for the industrially important austenitic steels. (au) 9 tabs., 94 ills., 177 refs.; The thesis is also available as DCAMM-R-S80 and as an electronic document on http://www.risoe.dk/rispubl

  9. Structural evolution and mechanisms of fatigue in polycrystalline brass

    International Nuclear Information System (INIS)

    The plastic strain controlled fatigue behaviour of polycrystalline Cu-15%Zn and Cu-30%Zn has been investigated with the aim of studying the effect of slip mode modification by the addition of zinc to copper. It has been clearly demonstrated, that true cyclic saturation does not occur in the plastic strain controlled fatigue of brass. This complicates the contstruction of a cyclic stress-strain (CSS) curve and thus the comparison with copper. A method to overcome this complication has been suggested. Surface observations on fatigued brass specimens show that individual grains tend to deform by Sachs type single slip. This behaviour has been described by the self-consistent Sachs-Eshelby model, which provides estimates of the CSS curve for brass polycrystals. Successive stages of primary hardening, softening and secondary hardening has been observed in the plastic strain controlled fatigue of brass. It has been found that the primary hardening is attributed to an increase of intergranular stresses whereas the secondary hardening apparently is attributed to an increase of friction stresses. Investigations of the structural evolution show that the softening behaviour can be explained by the presence of short-range order (SRO). SRO promote the formation of extended dipole arrays which hardens the material. The formation of intense shear bands destroy the dipole arrays, which explains the cyclic softening. The present results reveal that Cu-30%Zn in a pure planar slip alloy, while Cu-15%Zn displays both planar and wavy slip. The mechanical and structural behaviour observed in brass resembles recent observations in 316L austenitic stainless steels, and the present results reveal that Cu-30%Zn and 316L have approximately the same fatigue life curve. This emphasizes brass as being a convenient model system for the industrially important austenitic steels. (au)

  10. Structures of two molluscan hemocyanin genes: significance for gene evolution.

    Science.gov (United States)

    Lieb, B; Altenhein, B; Markl, J; Vincent, A; van Olden, E; van Holde, K E; Miller, K I

    2001-04-10

    We present here the description of genes coding for molluscan hemocyanins. Two distantly related mollusks, Haliotis tuberculata and Octopus dofleini, were studied. The typical architecture of a molluscan hemocyanin subunit, which is a string of seven or eight globular functional units (FUs, designated a to h, about 50 kDa each), is reflected by the gene organization: a series of eight structurally related coding regions in Haliotis, corresponding to FU-a to FU-h, with seven highly variable linker introns of 174 to 3,198 bp length (all in phase 1). In Octopus seven coding regions (FU-a to FU-g) are found, separated by phase 1 introns varying in length from 100 bp to 910 bp. Both genes exhibit typical signal (export) sequences, and in both cases these are interrupted by an additional intron. Each gene also contains an intron between signal peptide and FU-a and in the 3' untranslated region. Of special relevance for evolutionary considerations are introns interrupting those regions that encode a discrete functional unit. We found that five of the eight FUs in Haliotis each are encoded by a single exon, whereas FU-f, FU-g, and FU-a are encoded by two, three and four exons, respectively. Similarly, in Octopus four of the FUs each correspond to an uninterrupted exon, whereas FU-b, FU-e, and FU-f each contain a single intron. Although the positioning of the introns between FUs is highly conserved in the two mollusks, the introns within FUs show no relationship either in location nor phase. It is proposed that the introns between FUs were generated as the eight-unit polypeptide evolved from a monomeric precursor, and that the internal introns have been added later. A hypothesis for evolution of the ring-like quaternary structure of molluscan hemocyanins is presented. PMID:11287637

  11. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

    2011-07-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  12. The Structural Evolution of Forming and Early Stage Star Clusters

    Science.gov (United States)

    Jaehnig, Karl; Da Rio, Nicola; Tan, Jonathan C.

    2016-05-01

    We study the degree of angular substructure in the stellar position distribution of young members of Galactic star-forming regions, looking for correlations with distance from cluster center, surface number density of stars, and local dynamical age. To this end we adopt the catalog of members in 18 young (∼1-3 Myr) clusters from the Massive Young Star-Forming Complex Study in Infrared and X-ray (MYStIX) Survey and the statistical analysis of the Angular Dispersion Parameter, δADP. We find statistically significant correlation between δADP and physical projected distance from the center of the clusters, with the centers appearing smoother than the outskirts, consistent with more rapid dynamical processing on local dynamical, free-fall or orbital timescales. Similarly, smoother distributions are seen in regions of higher surface density, or older dynamical ages. These results indicate that dynamical processing that erases substructure is already well-advanced in young, sometimes still-forming, clusters. Such observations of the dissipation of substructure have the potential to constrain theoretical models of the dynamical evolution of young and forming clusters.

  13. Spectral properties of the temporal evolution of brain network structure

    Science.gov (United States)

    Wang, Rong; Zhang, Zhen-Zhen; Ma, Jun; Yang, Yong; Lin, Pan; Wu, Ying

    2015-12-01

    The temporal evolution properties of the brain network are crucial for complex brain processes. In this paper, we investigate the differences in the dynamic brain network during resting and visual stimulation states in a task-positive subnetwork, task-negative subnetwork, and whole-brain network. The dynamic brain network is first constructed from human functional magnetic resonance imaging data based on the sliding window method, and then the eigenvalues corresponding to the network are calculated. We use eigenvalue analysis to analyze the global properties of eigenvalues and the random matrix theory (RMT) method to measure the local properties. For global properties, the shifting of the eigenvalue distribution and the decrease in the largest eigenvalue are linked to visual stimulation in all networks. For local properties, the short-range correlation in eigenvalues as measured by the nearest neighbor spacing distribution is not always sensitive to visual stimulation. However, the long-range correlation in eigenvalues as evaluated by spectral rigidity and number variance not only predicts the universal behavior of the dynamic brain network but also suggests non-consistent changes in different networks. These results demonstrate that the dynamic brain network is more random for the task-positive subnetwork and whole-brain network under visual stimulation but is more regular for the task-negative subnetwork. Our findings provide deeper insight into the importance of spectral properties in the functional brain network, especially the incomparable role of RMT in revealing the intrinsic properties of complex systems.

  14. Spectral properties of the temporal evolution of brain network structure.

    Science.gov (United States)

    Wang, Rong; Zhang, Zhen-Zhen; Ma, Jun; Yang, Yong; Lin, Pan; Wu, Ying

    2015-12-01

    The temporal evolution properties of the brain network are crucial for complex brain processes. In this paper, we investigate the differences in the dynamic brain network during resting and visual stimulation states in a task-positive subnetwork, task-negative subnetwork, and whole-brain network. The dynamic brain network is first constructed from human functional magnetic resonance imaging data based on the sliding window method, and then the eigenvalues corresponding to the network are calculated. We use eigenvalue analysis to analyze the global properties of eigenvalues and the random matrix theory (RMT) method to measure the local properties. For global properties, the shifting of the eigenvalue distribution and the decrease in the largest eigenvalue are linked to visual stimulation in all networks. For local properties, the short-range correlation in eigenvalues as measured by the nearest neighbor spacing distribution is not always sensitive to visual stimulation. However, the long-range correlation in eigenvalues as evaluated by spectral rigidity and number variance not only predicts the universal behavior of the dynamic brain network but also suggests non-consistent changes in different networks. These results demonstrate that the dynamic brain network is more random for the task-positive subnetwork and whole-brain network under visual stimulation but is more regular for the task-negative subnetwork. Our findings provide deeper insight into the importance of spectral properties in the functional brain network, especially the incomparable role of RMT in revealing the intrinsic properties of complex systems. PMID:26723151

  15. The Co-evolution mechanism and stability analysis of service-oriented manufacturing enterprise system

    Directory of Open Access Journals (Sweden)

    Peipei Liang

    2015-11-01

    Full Text Available Purpose: Service-oriented manufacturing (SOM is a new worldwide trend in the manufacturing industry. An increasing number of enterprises have realized the advantages and importance of SOM. However, the co-evolution mechanism and the stability of service-oriented manufacturing enterprise systems have influences on the form and direction of evolution and decisions about how to determine the suitable scope of external investment. This paper aims to reveal the co-evolution mechanism and provide a scientific framework for the efficient operation of SOM enterprise system.Design/methodology: Based on a system’s features and the logistic equation, our research builds a three-dimensional dynamic model with three state variables: response capability, profitability, and structural complexity. In addition, an analysis of a system’s stability and state variables is conducted using the method of synergetics and, simultaneously, the threshold condition of co-evolution was determined and the evolution mechanism revealed. Finally, model validity is verified through the simulation of instance.Findings: By analyzing the dynamic model using Lyapounov stability analysis, the results show that responsiveness under the threshold condition will guide an enterprise system’s evolution for a long period of time, and whether the SOM enterprise system is stable or not depends on the external investment level ?. When the investment level reaches the threshold condition, system will realize its development and then repeatedly change from one kind of structure to another for an extended period. If not, system will be unstable, although it will improve, the rise in responsiveness will not be obvious.Originality/value: Most of the related researches are over-reliant on qualitative description and has seldom been from the perspective of a complex system. This work is a supplement from evolution perspective to SOM related theory researches, and also an innovation in the

  16. STRUCTURAL EVOLUTION AND COMPOSITION CHANGE IN THE SURFACE REGION OF POLYPROPYLENE/CLAY NANOCOMPOSITES ANNEALED AT HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    唐涛

    2009-01-01

    A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene(PP)/organically modified montmorillonite(OMMT) nanocomposites.The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation.The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis(TGA).The structural evolution and composition change in the surface region of...

  17. Structural evolution of tetragonal MnO2 and its electrochemical behavior

    Science.gov (United States)

    Shafi, P. Muhammed; Bose, A. Chandra

    2016-05-01

    MnO2 nanoparticles were synthesized by simple chemical precipitation method and were subjected to different heat treatment process. The structural evolution of as-prepared MnO2 nanoparticles at different annealing temperature was confirmed by XRD analysis. The weight loss as well as the heat flow associated with the thermal decomposition was studied by thermogravimetric analysis (TGA) along with differential thermal analysis (DTA). The functional group and phase formation were confirmed by Fourier transform infrared spectroscopy (FTIR). Finally electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge techniques. The cyclic voltammogram and charge-discharge curve of 450 ˚C annealed MnO2 nanoparticles exhibited relatively good capacitive behavior.

  18. Rational Engineering of Enzyme Allosteric Regulation through Sequence Evolution Analysis

    OpenAIRE

    Jae-Seong Yang; Sang Woo Seo; Sungho Jang; Gyoo Yeol Jung; Sanguk Kim

    2012-01-01

    Control of enzyme allosteric regulation is required to drive metabolic flux toward desired levels. Although the three-dimensional (3D) structures of many enzyme-ligand complexes are available, it is still difficult to rationally engineer an allosterically regulatable enzyme without decreasing its catalytic activity. Here, we describe an effective strategy to deregulate the allosteric inhibition of enzymes based on the molecular evolution and physicochemical characteristics of allosteric ligan...

  19. Structure and evolution of high-mass stellar mergers

    CERN Document Server

    Glebbeek, Evert; Zwart, Simon Portegies; Pols, Onno R

    2013-01-01

    In young dense clusters repeated collisions between massive stars may lead to the formation of a very massive star (above 100 Msun). In the past the study of the long-term evolution of merger remnants has mostly focussed on collisions between low-mass stars (up to about 2 Msun) in the context of blue-straggler formation. The evolution of collision products of more massive stars has not been as thoroughly investigated. In this paper we study the long-term evolution of a number of stellar mergers formed by the head-on collision of a primary star with a mass of 5-40 Msun with a lower mass star at three points in its evolution in order to better understand their evolution. We use smooth particle hydrodynamics (SPH) calculations to model the collision between the stars. The outcome of this calculation is reduced to one dimension and imported into a stellar evolution code. We follow the subsequent evolution of the collision product through the main sequence at least until the onset of helium burning. We find that l...

  20. Population genomics of dengue virus serotype 4: insights into genetic structure and evolution.

    Science.gov (United States)

    Waman, Vaishali P; Kasibhatla, Sunitha Manjari; Kale, Mohan M; Kulkarni-Kale, Urmila

    2016-08-01

    The spread of dengue disease has become a global public health concern. Dengue is caused by dengue virus, which is a mosquito-borne arbovirus of the genus Flavivirus, family Flaviviridae. There are four dengue virus serotypes (1-4), each of which is known to trigger mild to severe disease. Dengue virus serotype 4 (DENV-4) has four genotypes and is increasingly being reported to be re-emerging in various parts of the world. Therefore, the population structure and factors shaping the evolution of DENV-4 strains across the world were studied using genome-based population genetic, phylogenetic and selection pressure analysis methods. The population genomics study helped to reveal the spatiotemporal structure of the DENV-4 population and its primary division into two spatially distinct clusters: American and Asian. These spatial clusters show further time-dependent subdivisions within genotypes I and II. Thus, the DENV-4 population is observed to be stratified into eight genetically distinct lineages, two of which are formed by American strains and six of which are formed by Asian strains. Episodic positive selection was observed in the structural (E) and non-structural (NS2A and NS3) genes, which appears to be responsible for diversification of Asian lineages in general and that of modern lineages of genotype I and II in particular. In summary, the global DENV-4 population is stratified into eight genetically distinct lineages, in a spatiotemporal manner with limited recombination. The significant role of adaptive evolution in causing diversification of DENV-4 lineages is discussed. The evolution of DENV-4 appears to be governed by interplay between spatiotemporal distribution, episodic positive selection and intra/inter-genotype recombination. PMID:27169727

  1. Protein structure and evolution: are they constrained globally by a principle derived from information theory?

    Science.gov (United States)

    Hatton, Leslie; Warr, Gregory

    2015-01-01

    That the physicochemical properties of amino acids constrain the structure, function and evolution of proteins is not in doubt. However, principles derived from information theory may also set bounds on the structure (and thus also the evolution) of proteins. Here we analyze the global properties of the full set of proteins in release 13-11 of the SwissProt database, showing by experimental test of predictions from information theory that their collective structure exhibits properties that are consistent with their being guided by a conservation principle. This principle (Conservation of Information) defines the global properties of systems composed of discrete components each of which is in turn assembled from discrete smaller pieces. In the system of proteins, each protein is a component, and each protein is assembled from amino acids. Central to this principle is the inter-relationship of the unique amino acid count and total length of a protein and its implications for both average protein length and occurrence of proteins with specific unique amino acid counts. The unique amino acid count is simply the number of distinct amino acids (including those that are post-translationally modified) that occur in a protein, and is independent of the number of times that the particular amino acid occurs in the sequence. Conservation of Information does not operate at the local level (it is independent of the physicochemical properties of the amino acids) where the influences of natural selection are manifest in the variety of protein structure and function that is well understood. Rather, this analysis implies that Conservation of Information would define the global bounds within which the whole system of proteins is constrained; thus it appears to be acting to constrain evolution at a level different from natural selection, a conclusion that appears counter-intuitive but is supported by the studies described herein.

  2. CODSTRAN: Composite durability structural analysis

    Science.gov (United States)

    Chamis, C. C.; Smith, G. T.

    1978-01-01

    CODSTRAN (COmposite Durability STRuctural ANalysis) is an integrated computer program being developed for the prediction of defect growth and fracture of composite structures subjected to service loads and environments. CODSTRAN is briefly described with respect to organization, capabilities and present status. Application of CODSTRAN current capability to a flat composite laminate with a center slit which was subjected to axial tension loading predicted defect growth which is in good agreement with C-scan ultrasonic test records.

  3. Compact structure and proteins of pasta retard in vitro digestive evolution of branched starch molecular structure.

    Science.gov (United States)

    Zou, Wei; Sissons, Mike; Warren, Frederick J; Gidley, Michael J; Gilbert, Robert G

    2016-11-01

    The roles that the compact structure and proteins in pasta play in retarding evolution of starch molecular structure during in vitro digestion are explored, using four types of cooked samples: whole pasta, pasta powder, semolina (with proteins) and extracted starch without proteins. These were subjected to in vitro digestion with porcine α-amylase, collecting samples at different times and characterizing the weight distribution of branched starch molecules using size-exclusion chromatography. Measurement of α-amylase activity showed that a protein (or proteins) from semolina or pasta powder interacted with α-amylase, causing reduced enzymatic activity and retarding digestion of branched starch molecules with hydrodynamic radius (Rh)protein(s) was susceptible to proteolysis. Thus the compact structure of pasta protects the starch and proteins in the interior of the whole pasta, reducing the enzymatic degradation of starch molecules, especially for molecules with Rh>100nm. PMID:27516291

  4. Understanding the Structure and Evolution of Nearby Disk Galaxies

    Science.gov (United States)

    Zheng, Zheng

    2014-01-01

    In order to understand the structure and evolution of disk galaxies, we studied the stellar and gaseous components as well as the star formation rate in nearby disk galaxies. We used PS1 medium deep survey images to derive five-band (grizy) surface brightness profiles down to 30 ABmag/arcsec^2 for about 700 galaxies. From these stellar mass and mass-to-light ratio radial profiles are derived. The stellar mass radial profiles tend to bend-up at large radii, this often traces an extended old stellar population. The mass-to-light ratio profiles tend to rise outside the r25 radii. We also find a larger fraction of up-bending surface brightness profiles than Polen & Trujillo (2006). This may be because their sample is biased towards low surface brightness galaxies. We used HIPASS data as well as VLA HI 21cm data to study the gas component and dynamics of disk galaxies. We used the GALEX UV images to study the star formation of a HI-selected star-forming sample of about 400 galaxies, compiling a database of FUV and NUV radial profiles and related parameters. We used this to study the star forming efficiency (SFE, star formation rate per unit area divided by gas surface mass density) of the sample galaxies. We found that the UV based SFE has a tighter relationship with HI mass than an H_alpha based SFE as typically used in previous studies and the UV SFE is flat across wide range of stellar mass. We constructed a simple model to predict the distribution of interstellar medium and star formation rate in an equilibrium disk with constant two-fluid Toomre Q. This model can reproduces the SFE relations we derived.

  5. Structure and evolution of the magnetochrome domains: no longer alone

    Directory of Open Access Journals (Sweden)

    Pascal eArnoux

    2014-03-01

    Full Text Available Magnetotactic bacteria (MTB can swim along Earth’s magnetic field lines, thanks to the alignment of dedicated cytoplasmic organelles. These organelles, termed magnetosomes, are proteolipidic vesicles filled by a 35-120 nm crystal of either magnetite or greigite. The formation and alignment of magnetosomes are mediated by a group of specific genes, the mam genes, encoding the magnetosome-associated proteins. The whole process of magnetosome biogenesis can be divided into four sequential steps; (i cytoplasmic membrane invagination, (ii magnetosomes alignment, (iii iron crystal nucleation and (iv species-dependent mineral size and shape control. Since both magnetite and greigite are a mix of iron(III and iron(II, iron redox state management within the magnetosome vesicle is a key issue. Recently, studies have started pointing out the importance of a MTB-specific c-type cytochrome domain found in several magnetosome-associated proteins (MamE, P, T and X. This magnetochrome (MCR domain is almost always found in tandem, and this tandem is either found alone (MamT, in combination with a PDZ domain (MamP, a domain of unknown function (MamX or with a trypsin combined to one or two PDZ domains (MamE. By taking advantage of new genomic data available on MTB and a recent structural study of MamP, which helped define the MCR domain boundaries, we attempt to retrace the evolutionary history within and between the different MCR-containing proteins. We propose that the observed tandem repeat of MCR is the result of a convergent evolution and attempt to explain why this domain is rarely found alone.

  6. Structure and evolution of the magnetochrome domains: no longer alone.

    Science.gov (United States)

    Arnoux, Pascal; Siponen, Marina I; Lefèvre, Christopher T; Ginet, Nicolas; Pignol, David

    2014-01-01

    Magnetotactic bacteria (MTB) can swim along Earth's magnetic field lines, thanks to the alignment of dedicated cytoplasmic organelles. These organelles, termed magnetosomes, are proteolipidic vesicles filled by a 35-120 nm crystal of either magnetite or greigite. The formation and alignment of magnetosomes are mediated by a group of specific genes, the mam genes, encoding the magnetosome-associated proteins. The whole process of magnetosome biogenesis can be divided into four sequential steps; (i) cytoplasmic membrane invagination, (ii) magnetosomes alignment, (iii) iron crystal nucleation and (iv) species-dependent mineral size and shape control. Since both magnetite and greigite are a mix of iron (III) and iron (II), iron redox state management within the magnetosome vesicle is a key issue. Recently, studies have started pointing out the importance of a MTB-specific c-type cytochrome domain found in several magnetosome-associated proteins (MamE, P, T, and X). This magnetochrome (MCR) domain is almost always found in tandem, and this tandem is either found alone (MamT), in combination with a PDZ domain (MamP), a domain of unknown function (MamX) or with a trypsin combined to one or two PDZ domains (MamE). By taking advantage of new genomic data available on MTB and a recent structural study of MamP, which helped define the MCR domain boundaries, we attempt to retrace the evolutionary history within and between the different MCR-containing proteins. We propose that the observed tandem repeat of MCR is the result of a convergent evolution and attempt to explain why this domain is rarely found alone. PMID:24723915

  7. Real Time Pore Structure Evolution during Olivine Mineral Carbonation

    Science.gov (United States)

    Zhu, W.; Fusseis, F.; Lisabeth, H. P.; Xiao, X.

    2014-12-01

    Aqueous carbonation of ultramafic rocks has been proposed as a promising method for long-term, secure sequestration of carbon dioxide. While chemical kinetics data indicate that carbonation reaction in olivine is one of the fastest among the mg-bearing minerals, in practice, the factors that limit the extent and rate of carbonation in ultramafic rocks are fluid supply and flux. On the one hand, reaction products could produce passivating layer that prohibits further reactions. On the other hand, the increases in solid volume during carbonation could lead to cracking and create new fluid paths. Whether carbonation in ultramafic rocks is self-limiting or self-sustaining has been hotly debated. Experimental evidence of precipitation of reaction products during olivine carbonation was reported. To date, reaction-driven cracking has not been observed. In this paper, we present the first real-time pore structure evolution data using the x-ray synchrotron microtomography. Sodium bicarbonate (NaHCO3) solution was injected into porous olivine aggregates and in-situ pore structure change during olivine carbonation at a constant confining pressure (12 MPa) and a temperature of 200oC was captured at 30 min. interval for ~160 hours. Shortly after the experiment started, filling-in of the existing pores by precipitation of reaction products was visible. The size of the in-fills kept increasing as reactions continued. After ~48 hours, cracking around the in-fill materials became visible. After ~60 hours, these cracks started to show a clear polygonal pattern, similar to the crack patterns usually seen on the surface of drying mud. After ~72 hours, some of the cracks coalesced into large fractures that cut-through the olivine aggregates. New fractures continued to develop and at the end of the experiment, the sample was completely disintegrated by these fractures. We also conducted nanotomography experiments on a sub-volume of the reacted olivine aggregate. Orthogonal sets of

  8. Chromatin structure and evolution in the human genome

    Directory of Open Access Journals (Sweden)

    Dunlop Malcolm G

    2007-05-01

    Full Text Available Abstract Background Evolutionary rates are not constant across the human genome but genes in close proximity have been shown to experience similar levels of divergence and selection. The higher-order organisation of chromosomes has often been invoked to explain such phenomena but previously there has been insufficient data on chromosome structure to investigate this rigorously. Using the results of a recent genome-wide analysis of open and closed human chromatin structures we have investigated the global association between divergence, selection and chromatin structure for the first time. Results In this study we have shown that, paradoxically, synonymous site divergence (dS at non-CpG sites is highest in regions of open chromatin, primarily as a result of an increased number of transitions, while the rates of other traditional measures of mutation (intergenic, intronic and ancient repeat divergence as well as SNP density are highest in closed regions of the genome. Analysis of human-chimpanzee divergence across intron-exon boundaries indicates that although genes in relatively open chromatin generally display little selection at their synonymous sites, those in closed regions show markedly lower divergence at their fourfold degenerate sites than in neighbouring introns and intergenic regions. Exclusion of known Exonic Splice Enhancer hexamers has little affect on the divergence observed at fourfold degenerate sites across chromatin categories; however, we show that closed chromatin is enriched with certain classes of ncRNA genes whose RNA secondary structure may be particularly important. Conclusion We conclude that, overall, non-CpG mutation rates are lowest in open regions of the genome and that regions of the genome with a closed chromatin structure have the highest background mutation rate. This might reflect lower rates of DNA damage or enhanced DNA repair processes in regions of open chromatin. Our results also indicate that dS is a poor

  9. Analysis of the Structuration Evolution Mechanism of Inter-firm Collaborative Knowledge Creation%企业间合作知识创造的结构化演变机理研究

    Institute of Scientific and Technical Information of China (English)

    韩晓琳; 张庆普; 单伟

    2012-01-01

    深入理解合作知识创造机理有助于构建有效的合作知识创造管理模式,促进企业间的合作知识创造进程.可是,由于合作企业在战略规划、利益机制、企业文化和管理模式等方面存在差异,合作知识创造的机理非常复杂.在阐明结构化理论和合作知识创造理论一致性的基础上,应用结构二重性原理,从合作博弈、表意结构、支配结构和合法化结构四个维度对企业间合作知识创造的结构化演变机理进行了剖析,并构建了基于结构化模态的合作知识创造管理模式,以有效提高企业间合作知识创造绩效.%Mastering collaborative knowledge creation mechanism can contribute to constructing effective collaborative knowledge creation management mode, and promoting inter- firm collaborative knowledge creation process. However, because of the differences of inter-firm in strategic planning, interest mechanism, corporate culture and management mode, collaborative knowledge creation mechanism is very complex. On the basis of clarifying the consistency between structuration theory and collaborative knowledge creation theory, this paper analyzes the structuration evolution mechanism of inter-firm collaborative knowledge creation from four dimensions: collaborative game, signification, domination, and legitimation. Based on the structuration mode, the paper constructs the collaborative knowledge creation management mode to improve the inter-firm collaborative knowledge creation performance.

  10. Probability Density Evolution Analysis for Stochastic Dynamic Seismic Responses of Structures Based on Improved Point Estimation Method%基于改进点估计法的结构随机动力地震反应概率密度演化

    Institute of Scientific and Technical Information of China (English)

    宋鹏彦; 吕大刚; 于晓辉; 王光远

    2014-01-01

    为了获得结构反应概率密度随时间的变化规律,将改进的点估计法、最大熵原理与随机动力学的概率密度演化理论相结合,提出了基于统计矩信息的结构非线性随机动力反应概率密度演化分析方法。以一栋按我国规范设计的钢筋混凝土框架结构为研究对象,选取结构在地震作用下的顶层位移和整体地震损伤指数作为反应参数,并考虑结构参数的不确定性,用本文提出的方法进行了地震作用下结构的非线性随机动力反应的概率密度演化分析及参数灵敏度分析,结果表明:钢筋屈服强度、结构的阻尼、混凝土容重对结构的位移反应影响较为明显,灵敏度超过10%。%In order to obtain the law of probability densities of structural responses varying with time, a new moment-based approach for analysis of probability density evolution of nonlinear stochastic dynamic responses of structures was developed,by combining an improved point estimation method (IPEM)with the maximum entropy theory and the probability density evolution theory for stochastic dynamics of structures. The proposed method was then used to perform probabilistic density evolution analysis and parameter sensitivity analysis of a reinforced concrete (RC ) frame structure designed according to Chinese codes,selecting the top displacement and global seismic damage index of the structure under earthquake as response parameters,and taking into account the uncertainty of structural parameters. The results show that the steel yield strength,the structural damping ratio,and concrete gravity density have dominant influences on structural displacement,with a sensitivity of more than 10%.

  11. Social dilemmas in an online social network: The structure and evolution of cooperation

    International Nuclear Information System (INIS)

    We investigate two paradigms for studying the evolution of cooperation-Prisoner's Dilemma and Snowdrift game in an online friendship network, obtained from a social networking site. By structural analysis, it is revealed that the empirical social network has small-world and scale-free properties. Besides, it exhibits assortative mixing pattern. Then, we study the evolutionary version of the two types of games on it. It is found that cooperation is substantially promoted with small values of game matrix parameters in both games. Whereas the competent cooperators induced by the underlying network of contacts will be dramatically inhibited with increasing values of the game parameters. Further, we explore the role of assortativity in evolution of cooperation by random edge rewiring. We find that increasing amount of assortativity will to a certain extent diminish the cooperation level. We also show that connected large hubs are capable of maintaining cooperation. The evolution of cooperation on empirical networks is influenced by various network effects in a combined manner, compared with that on model networks. Our results can help understand the cooperative behaviors in human groups and society

  12. Evolution of grain and subgrain structure during cold rolling of commercial-purity titanium

    International Nuclear Information System (INIS)

    Research highlights: → EBSD analysis of cold-rolled titanium revealed three stages of structure evolution. → These stages are defined by plots of the boundaries density as a function of strain. → The first stage is associated with twinning. → Dislocation density increases and substructure forms at the second stage. → The third stage is related to the formation of high-angle boundaries. - Abstract: The evolution of microstructure in commercial-purity titanium during cold rolling to a thickness strain of 2.6 was quantified using electron backscatter diffraction. The measurements were analyzed in terms of the mean grain size and the density of boundaries (the ratio of total boundary length to the scanned area). The density of high-angle boundaries as a function of thickness strain had three distinct stages, each of which was associated with a different mechanism of microstructure formation, i.e., (i) twinning, (ii) an increase in dislocation density and the formation of substructure, and (iii) the formation of deformation-induced high-angle boundaries. The influence of twinning on the kinetics of microstructure evolution was also interpreted.

  13. Structural analysis of aligned RNAs.

    Science.gov (United States)

    Voss, Björn

    2006-01-01

    The knowledge about classes of non-coding RNAs (ncRNAs) is growing very fast and it is mainly the structure which is the common characteristic property shared by members of the same class. For correct characterization of such classes it is therefore of great importance to analyse the structural features in great detail. In this manuscript I present RNAlishapes which combines various secondary structure analysis methods, such as suboptimal folding and shape abstraction, with a comparative approach known as RNA alignment folding. RNAlishapes makes use of an extended thermodynamic model and covariance scoring, which allows to reward covariation of paired bases. Applying the algorithm to a set of bacterial trp-operon leaders using shape abstraction it was able to identify the two alternating conformations of this attenuator. Besides providing in-depth analysis methods for aligned RNAs, the tool also shows a fairly well prediction accuracy. Therefore, RNAlishapes provides the community with a powerful tool for structural analysis of classes of RNAs and is also a reasonable method for consensus structure prediction based on sequence alignments. RNAlishapes is available for online use and download at http://rna.cyanolab.de. PMID:17020924

  14. Compensatory evolution of a precursor messenger RNA secondary structure in the Drosophila melanogaster Adh gene

    Science.gov (United States)

    Chen, Ying; Stephan, Wolfgang

    2003-01-01

    Evidence for the evolutionary maintenance of a hairpin structure possibly involved in intron processing had been found in intron 1 of the alcohol dehydrogenase gene (Adh) in diverse Drosophila species. In this study, the putative hairpin structure was evaluated systematically in Drosophila melanogaster by elimination of either side of the stem using site-directed mutagenesis. The effects of these mutations and the compensatory double mutant on intron splicing efficiency and ADH protein production were assayed in Drosophila melanogaster Schneider L2 cells and germ-line transformed adult flies. Mutations that disrupt the putative hairpin structure right upstream of the intron branch point were found to cause a significant reduction in both splicing efficiency and ADH protein production. In contrast, the compensatory double mutant that restores the putative hairpin structure was indistinguishable from the WT in both splicing efficiency and ADH level. It was also observed by mutational analysis that a more stable secondary structure (with a longer stem) in this intron decreases both splicing efficiency and ADH protein production. Implications for RNA secondary structure and intron evolution are discussed. PMID:12972637

  15. Compact structure and proteins of pasta retard in vitro digestive evolution of branched starch molecular structure.

    Science.gov (United States)

    Zou, Wei; Sissons, Mike; Warren, Frederick J; Gidley, Michael J; Gilbert, Robert G

    2016-11-01

    The roles that the compact structure and proteins in pasta play in retarding evolution of starch molecular structure during in vitro digestion are explored, using four types of cooked samples: whole pasta, pasta powder, semolina (with proteins) and extracted starch without proteins. These were subjected to in vitro digestion with porcine α-amylase, collecting samples at different times and characterizing the weight distribution of branched starch molecules using size-exclusion chromatography. Measurement of α-amylase activity showed that a protein (or proteins) from semolina or pasta powder interacted with α-amylase, causing reduced enzymatic activity and retarding digestion of branched starch molecules with hydrodynamic radius (Rh)pasta protects the starch and proteins in the interior of the whole pasta, reducing the enzymatic degradation of starch molecules, especially for molecules with Rh>100nm.

  16. Models of the Protocellular Structures, Functions and Evolution

    Science.gov (United States)

    Pohorille, Andrew; New, Michael; Keefe, Anthony; Szostak, Jack W.; Lanyi, Janos F.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    In the absence of extinct or extant record of protocells, the most direct way to test our understanding of the origin of cellular life is to construct laboratory models that capture important features of protocellular systems. Such efforts are currently underway in a collaborative project between NASA-Ames, Harvard medical School and University of California. They are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures. The centerpiece of this project is a method for the in vitro evolution of protein enzymes toward arbitrary catalytic targets. A similar approach has already been developed for nucleic acids: First, a very large population of candidate molecules is generated using a random synthetic approach. Next, the small numbers of molecules that can accomplish the desired task are selected. These molecules are next vastly multiplied using the polymerase chain reaction. A mutagenic approach, in which the sequences of selected molecules are randomly altered, can yield further improvements in performance or alterations of specificities. Unfortunately, the catalytic potential of nucleic acids is rather limited. Proteins are more catalytically capable but cannot be directly amplified. In the new technique, this problem is circumvented by covalently linking each protein of the initial, diverse, pool to the RNA sequence that codes for it. Then, selection is performed on the proteins, but the nucleic acids are replicated. To date, we have obtained "a proof of concept" by evolving simple, novel proteins capable of selectively binding adenosine tri-phosphate (ATP). Our next goal is to create an enzyme that can phosphorylate amino acids and another to catalyze the formation of peptide bonds in the absence of nucleic acid templates. This latter reaction does not take place in contemporary cells. once developed, these enzymes will be encapsulated in liposomes so that they will function in a simulated cellular

  17. Kinematic and Structural Evolution of Field and Cluster Spiral Galaxies

    CERN Document Server

    Ziegler, Bodo L; Da Rocha, Cristiano; Böhm, Asmus; Peletier, Reynier F; Verdugo, Miguel

    2009-01-01

    To understand the processes that build up galaxies we investigate the stellar structure and gas kinematics of spiral and irregular galaxies out to redshift 1. We target 92 galaxies in four cluster (z = 0.3 & 0.5) fields to study the environmental influence. Their stellar masses derived from multiband VLT/FORS photometry are distributed around but mostly below the characteristic Schechter-fit mass. From HST/ACS images we determine morphologies and structural parameters like disk length, position angle and ellipticity. Combining the spectra of three slit positions per galaxy using the MXU mode of VLT/FORS2 we construct the two-dimensional velocity field from gas emission lines for 16 cluster members and 33 field galaxies. The kinematic position angle and flatness are derived by a Fourier expansion of elliptical velocity profiles. To trace possible interaction processes, we define three irregularity indicators based on an identical analysis of local galaxies from the SINGS project. Our distant sample display...

  18. Modeling solidification structure evolution and microsegregation under pressure condition

    Institute of Scientific and Technical Information of China (English)

    Qiang Li; Qiaoyi Guo; Rongde Li

    2006-01-01

    Solidification microstructure and microsegregation were simulated under a constant pressure condition using the cellular automaton method. First, a single dendrite evolution was simulated and compared under pressure condition and under normal condition,respectively. The solidification microstructure and microsegregation were then simulated. Through simulation, it may be concluded that if the growth direction of the dendrite is parallel to the pressure direction, dendrite growth will be hindered. On the other hand,pressure has no influence on the dendrite evolution. However, when two dendrites grow in close contact, solute enrichment occurs in the dendrites, which hinders the growth of the dendrites. In addition, the solute is preferentially enriched along the pressure direction.

  19. Structural Analysis of Plate Based Tensegrity Structures

    DEFF Research Database (Denmark)

    Hald, Frederik; Kirkegaard, Poul Henning; Damkilde, Lars

    2013-01-01

    Plate tensegrity structures combine tension cables with a cross laminated timber plate and can then form e.g. a roof structure. The topology of plate tensegrity structures is investigated through a parametric investigation. Plate tensegrity structures are investigated, and a method for...... determination of the structures pre-stresses is used. A parametric investigation is performed to determine a more optimized form of the plate based tensegrity structure. Conclusions of the use of plate based tensegrity in civil engineering and further research areas are discussed....

  20. Gene finding with a hidden Markov model of genome structure and evolution

    DEFF Research Database (Denmark)

    Pedersen, Jakob Skou; Hein, Jotun

    2003-01-01

    annotation. The modelling of evolution by the existing comparative gene finders leaves room for improvement. Results: A probabilistic model of both genome structure and evolution is designed. This type of model is called an Evolutionary Hidden Markov Model (EHMM), being composed of an HMM and a set of region...

  1. Structure and evolution of the Y-chromosomal and mitochondrial DNA of cattle

    NARCIS (Netherlands)

    Verkaar, Edward Louis Christian

    2004-01-01

    The research described in this thesis is focused on the structure and evolution of the bovine Y-chromosome and the use of paternal markers in molecular diagnostics. The Y-chromosome has emerged together with the X-chromosome early during the evolution of the mammals by differentiation of a pair of a

  2. Analysis of the Science and Technology Preservice Teachers' Opinions on Teaching Evolution and Theory of Evolution

    Science.gov (United States)

    Töman, Ufuk; Karatas, Faik Özgür; Çimer, Sabiha Odabasi

    2014-01-01

    In this study, we investigate of science and technology teachers' opinions about the theory of evolution and the evolution teaching. The aim of this study, we investigate of science and technology teachers' opinions about the theory of evolution and the evolution teaching. This study is a descriptive study. Open-ended questions were used to…

  3. China’s Structural Energy Conservation: Analysis and Proposals

    Institute of Scientific and Technical Information of China (English)

    张雷; 黄园淅

    2008-01-01

    Given the increasing dependence of development on energy consumption, an understanding of the rules and trends of national energy consumption is required for boosting social energy conservation. By using two models -- the structural evolution energy consumption model and the structural evolution per-unit energy consumption model, this article attempts to make an international comparison of the industrial structure development versus energy consumption patterns in the United States, the United Kingdom, France, Germany, Japan, and India. The results of this analysis indicate that the dominance of secondary industry over the industrial structure evolution process noticeably accelerates national energy consumption at the initial stage of modernization. Subsequently, a slowdown in energy consumption as a result of industrial structure development yields effects as the diversification process speeds up. Under such influence, energy consumption per unit of GDP follows an inverted U-shaped curve from rise to decline. As one of the world’s major energy producers and consumers, China has long employed a one- sided sector development policy. Under the influence of this policy, national energy conservation endeavors have been inhibited by the rigidity in its industry structural evolution. Thus, in China, energy consumption per unit of GDP has remained at a high level.

  4. Structural Analysis of Complex Networks

    CERN Document Server

    Dehmer, Matthias

    2011-01-01

    Filling a gap in literature, this self-contained book presents theoretical and application-oriented results that allow for a structural exploration of complex networks. The work focuses not only on classical graph-theoretic methods, but also demonstrates the usefulness of structural graph theory as a tool for solving interdisciplinary problems. Applications to biology, chemistry, linguistics, and data analysis are emphasized. The book is suitable for a broad, interdisciplinary readership of researchers, practitioners, and graduate students in discrete mathematics, statistics, computer science,

  5. Temporal evolution of the chemical structure during the pattern transfer by ion-beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ha, N.-B.; Jeong, S.; Yu, S.; Ihm, H.-I.; Kim, J.-S.

    2015-01-01

    Highlights: • Chemical analyses of the individual nano structures simultaneously with the investigation of their morphological evolution were performed. • Degradation of the transferred pattern starts before the overlayer is fully removed. • The chemical analysis reveals the severe reduction of the sputter yield of the material forming the overlayer near the interface due to the compound formation, requesting caution in the practice of the pattern transfer. - Abstract: Ru films patterned by ion-beam sputtering (IBS) serve as sacrificial masks for the transfer of the patterns to Si(1 0 0) and metallic glass substrates by continued IBS. Under the same sputter condition, however, both bare substrates remain featureless. Chemical analyses of the individual nano structures simultaneously with the investigation of their morphological evolution reveal that the pattern transfer, despite its apparent success, suffers from premature degradation before the mask is fully removed by IBS. Moreover, the residue of the mask or Ru atoms stubbornly remains near the surface, resulting in unintended doping or alloying of both patterned substrates.

  6. The Evolution and Internal Structure of Jupiter and Saturn with Compositional Gradients

    CERN Document Server

    Vazan, A; Podolak, M; Kovetz, A

    2016-01-01

    The internal structure of gas giant planets may be more complex than the commonly assumed core-envelope structure with an adiabatic temperature profile. Different primordial internal structures as well as various physical processes can lead to non-homogenous compositional distributions. A non-homogenous internal structure has a significant impact on the thermal evolution and final structure of the planets. In this paper, we present alternative structure and evolution models for Jupiter and Saturn allowing for non-adiabatic primordial structures and the mixing of heavy elements by convection as these planets evolve. We present the evolution of the planets accounting for various initial composition gradients, and in the case of Saturn, include the formation of a helium-rich region as a result of helium rain. We investigate the stability of regions with composition gradients against convection, and find that the helium shell in Saturn remains stable and does not mix with the rest of the envelope. In other cases,...

  7. Downstream Evolution of Longitudinal Embedded Vortices with Helical Structure

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Okulov, Valery; Hansen, Martin Otto Laver

    2009-01-01

    In the present work the downstream development of device induced vortices with helical symmetry embedded in wall bounded flow on a bump is studied with the aid of Stereoscopic Particle Image Velocimetry (SPIV). The downstream evolution of characteristic parameters of helical vortices is studied...

  8. Properties and evolution of anisotropic structures in collisionless plasmas

    CERN Document Server

    Karimov, A R; Stenflo, L

    2016-01-01

    A new class of exact electrostatic solutions of the Vlasov-Maxwell equations based on the Jeans's theorem is proposed for studying the evolution and properties of two-dimensional anisotropic plasmas that are far from thermodynamic equilibrium. In particular, the free expansion of a slab of electron-ion plasma into vacuum is investigated.

  9. The Structure and Evolution of Quasi-stars

    CERN Document Server

    Ball, Warrick H; Zytkow, Anna N; Eldridge, John J

    2011-01-01

    The existence of bright quasars at high redshifts implies that supermassive black holes were able to form in the early Universe. Though a number of mechanisms to achieve this have been proposed, none yet stands out. A recent suggestion is the formation of quasi-stars, initially stellar-mass black holes accreting from hydrostatic giant-like envelopes of gas, formed from the monolithic collapse of pre-galactic gas clouds. In this work, we modify the Cambridge STARS stellar evolution package to construct detailed models of the evolution of these objects. We find that, in all of our models, the black hole inside the envelope is able to reach slightly more than one-tenth of the total mass of the system before hydrostatic equilibrium breaks down. This breakdown occurs after a few million years of evolution. We show that the mechanism which causes the hydrostatic evolution to end is present in polytropic models. We also show that the solutions are highly sensitive to the size of the inner boundary radius and that no...

  10. Stereological analysis of spatial structures

    DEFF Research Database (Denmark)

    Hansen, Linda Vadgård

    The thesis deals with stereological analysis of spatial structures. One area of focus has been to improve the precision of well-known stereological estimators by including information that is available via automatic image analysis. Furthermore, the thesis presents a stochastic model for star......-shaped three-dimensional objects using the radial function. It appears that the model is highly fleksiblel in the sense that it can be used to describe an object with arbitrary irregular surface. Results on the distribution of well-known local stereological volume estimators are provided....

  11. Red Nuggets at High Redshift: Structural Evolution of Quiescent Galaxies Over 10 Gyr of Cosmic History

    CERN Document Server

    Damjanov, Ivana; Glazebrook, Karl; McCarthy, Patrick J; Caris, Evelyn; Carlberg, Raymond G; Chen, Hsiao-Wen; Crampton, David; Green, Andrew W; Jørgensen, Inger; Juneau, Stéphanie; Borgne, Damien Le; Marzke, Ronald O; Mentuch, Erin; Murowinski, Richard; Roth, Kathy; Savaglio, Sandra; Yan, Haojing

    2011-01-01

    We present an analysis of the size growth seen in early-type galaxies over 10 Gyr of cosmic time. Our analysis is based on a homogeneous synthesis of published data from 17 spectroscopic surveys observed at similar spatial resolution, augmented by new measurements for galaxies in the Gemini Deep Deep Survey. In total, our sample contains structural data for 465 galaxies (mainly early-type) in the redshift range 0.2evolution of passively-evolving galaxies over this redshift range is gradual and continuous, with no evidence for an end or change to the process around z~1, as has been hinted at by some surveys which analyze subsets of the data in isolation. The size growth appears to be independent of stellar mass, with the mass-normalized half-light radius scaling with redshift as R_e (1+z)^(-1.62 +/- 0.34). Surprisingly, this power law seems to be in good agreement with the recently reported continuous size evolution of UV-bright galaxies in the redshift range z~0.5-3.5. It is also in acc...

  12. Generalized Dromion Structures of New (2 + 1)-Dimensional Nonlinear EvolutionEquation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie-Fang

    2001-01-01

    We derive the generalized dromions of the new (2 + 1)-dimensional nonlinear evolution equation by the arbitrary function presented in the bilinearized linear equations. The rich soliton and dromion structures for this system are released.

  13. Alpha-synuclein gene structure,evolution,and protein aggregation

    Institute of Scientific and Technical Information of China (English)

    Lili Xiong; Peng Zhao; Zhiyun Guo; Jianhua Zhang; Diqiang Li; Canquan Mao

    2010-01-01

    α-synuclein,a member of the synuclein family,is predominately expressed in brain tissues,where it is the major component of Lewy bodies,the major hallmark of Parkinson's disease.We analyzed the phylogenetics,gene structure,and effects of different forms of α-synuclein on in vitro protein aggregation.The synuclein phylogenetic tree showed that sequences could be classified into α,β,and γ protein groups.The orthologous gene α-,β-and γ-synuclein showed similar evolutionary distance to the paralogous gene α-,β-and γ-synuclein.Bioinformatics analysis suggests that the amino-acid sequence of human α-synuclein can be divided into three regions: N-terminal amphipathic region(1-60),central hydrophobic non-amyloid beta component segment(61-95),and the C-terminal acidic part(96-140).The mutant site of A30P is at the second exon of α-synuclein,whereas E46K is located at the third exon of α-synuclein.α-synuclein alternative splicing results in four isomers,and five exons,all of which participate in protein coding,comprising 140 amino acids to produce the major α-synuclein in vivo.The threeα-synuclein isoforms are products of alternative splicing,α-synuclein 126,112 and 98.We also review the genetic and cellular factors that affect the aggregation of α-synuclein and compounds that inhibit aggregation.A better understanding of α-synuclein sequences,structure,and function may allow better targeted therapy and diagnosis of α-synuclein in Parkinson's disease and other neurodegenerative diseases.

  14. Distribution functions for internal interface energy as a characteristic of submicrocrystalline copper structure evolution under low-temperature annealing

    Science.gov (United States)

    Kuznetsov, P.; Rakhmatulina, T.; Koznikov, A.; Belyaeva, I.

    2015-10-01

    Submicrocrystalline structure of 99.99% pure copper produced by equal channel angular pressing was under investigation. After deformation the samples were subjected to low-temperature annealing. Grain and subgrain structure was studied by scanning tunnel microscopy. Internal interface energy was estimated using the method based on measurement of dihedral angles (ψ) of the boundary grooves formed by electrochemical etching. Analysis of the differential and cumulative distribution functions for relative grain boundary energy enabled to qualitatively evaluate energy redistribution between the boundaries of different types and internal bulk crystallites and to study evolution of submicrocrystalline structure under low-temperature annealing.

  15. Evolution of collective action in adaptive social structures.

    Science.gov (United States)

    Moreira, João A; Pacheco, Jorge M; Santos, Francisco C

    2013-01-01

    Many problems in nature can be conveniently framed as a problem of evolution of collective cooperative behaviour, often modelled resorting to the tools of evolutionary game theory in well-mixed populations, combined with an appropriate N-person dilemma. Yet, the well-mixed assumption fails to describe the population dynamics whenever individuals have a say in deciding which groups they will participate. Here we propose a simple model in which dynamical group formation is described as a result of a topological evolution of a social network of interactions. We show analytically how evolutionary dynamics under public goods games in finite adaptive networks can be effectively transformed into a N-Person dilemma involving both coordination and co-existence. Such dynamics would be impossible to foresee from more conventional 2-person interactions as well as from descriptions based on infinite, well-mixed populations. Finally, we show how stochastic effects help rendering cooperation viable, promoting polymorphic configurations in which cooperators prevail.

  16. Shallow nitrogen ion implantation: Evolution of chemical state and defect structure in titanium

    Science.gov (United States)

    Manojkumar, P. A.; Chirayath, V. A.; Balamurugan, A. K.; Krishna, Nanda Gopala; Ilango, S.; Kamruddin, M.; Amarendra, G.; Tyagi, A. K.; Raj, Baldev

    2016-09-01

    Evolution of chemical states and defect structure in titanium during low energy nitrogen ion implantation by Plasma Immersion Ion Implantation (PIII) process is studied. The underlying process of chemical state evolution is investigated using secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The implantation induced defect structure evolution as a function of dose is elucidated using variable energy positron annihilation Doppler broadening spectroscopy (PAS) and the results were corroborated with chemical state. Formation of 3 layers of defect state was modeled to fit PAS results.

  17. Molecular evolution, intracellular organization, and the quinary structure of proteins.

    OpenAIRE

    McConkey, E H

    1982-01-01

    High-resolution two-dimensional polyacrylamide gel electrophoresis shows that at least half of 370 denatured polypeptides from hamster cells and human cells are indistinguishable in terms of isoelectric points and molecular weights. Molecular evolution may have been more conservative for this set of proteins than sequence studies on soluble proteins have implied. This may be a consequence of complexities of intracellular organization and the numerous macromolecular interactions in which most ...

  18. Organizational culture evolution - problems of structure and competence

    OpenAIRE

    Eugenia Campeanu-Sonea; Adrian Sonea

    2006-01-01

    The paper contains 4 chapters: 1. the organizational culture - an authors vision concerning this definition and this main variables; 2. the competence on the organisational level as the objective of this culture development; the process of learning and skills capitalisation in order to fulfil the customer requirements; 3. the changing process in organization - an authors rewritten after the models of Nadler and Greiner, analysing the stages of the evolution companies; 4. the organizational st...

  19. [Genomic structure of the autotetraploid oat species Avena macrostachya inferred from comparative analysis of the ITS1 and ITS2 sequences: on the oat karyotype evolution during the early stages of the Avena species divergence].

    Science.gov (United States)

    Rodionov, A V; Tiupa, N B; Kim, E S; Machs, E M; Loskutov, I G

    2005-05-01

    To examine the genomic structure of Avena macrostachya, internal transcribed spacers, ITS1 and ITS2, as well as nuclear 5.8S tRNA genes from three oat species with AsAs karyotype (A. wiestii, A. hirtula, and A. atlantica), and those from A. longiglumis (AlAl), A. canariensis (AcAc), A. ventricosa (CvCv), A. pilosa, and A. clauda (CpCp) were sequenced. All species of the genus Avena examined represented a monophyletic group (bootstrap index = 98), within which two branches, i.e., species with A- and C-genomes, were distinguished (bootstrap indices = 100). The subject of our study, A. macrostachya, albeit belonging to the phylogenetic branch of C-genome oat species (karyotype with submetacentic and subacrocentric chromosomes), has preserved an isobrachyal karyotype, (i.e., that containing metacentric chromosomes), probably typical of the common Avena ancestor. It was suggested to classify the A. macrostachya genome as a specific form of C-genome, Cm-genome. Among the species from other genera studied, Arrhenatherum elatius was found to be the closest to Avena in ITS1 and ITS structure. Phylogenetic relationships between Avena and Helictotrichon remain intriguingly uncertain. The HPR389153 sequence from H. pratense genome was closest to the ITS1 sequences specific to the Avena A-genomes (p-distance = 0.0237), while the differences of this sequence from the ITS1 of A. macrostachya reached 0.1221. On the other hand, HAD389117 from H. adsurgens was close to the ITS1 specific to Avena C-genomes (p-distance = 0.0189), while its differences from the A-genome specific ITS1 sequences reached 0.1221. It seems likely that the appearance of highly polyploid (2n = 12-21x) species of H. pratense and H. adsurgens could be associated with interspecific hybridization involving Mediterranean oat species carrying A- and C-genomes. A hypothesis on the pathways of Avena chromosomes evolution during the early stages the oat species divergence is proposed.

  20. MICROMECHANICS ANALYSIS ON EVOLUTION OF CRACK IN VISCOELASTIC MATERIALS

    Institute of Scientific and Technical Information of China (English)

    张双寅

    2002-01-01

    A preliminary analysis on crack evolution in viscoelastic materials was presented Based on the equivalent inclusion concept of micro mechanics theory, the explicit expressions of crack opening displacement δ and energy release rate G were derived,indicating that both δ and G are increasing with time. The equivalent modulus of the viscoelastic solid comprising cracks was evaluated. It is proved that the decrease of the modulus comes from two mechanisms: one is the viscoelasticity of the material; the other is the crack opening which is getting larger with time.

  1. Space-time isogeometric analysis of parabolic evolution problems

    Science.gov (United States)

    Langer, Ulrich; Moore, Stephen E.; Neumüller, Martin

    2016-07-01

    We present and analyze a new stable space-time Isogeometric Analysis (IgA) method for the numerical solution of parabolic evolution equations in fixed and moving spatial computational domains. The discrete bilinear form is elliptic on the IgA space with respect to a discrete energy norm. This property together with a corresponding boundedness property, consistency and approximation results for the IgA spaces yields an a priori discretization error estimate with respect to the discrete norm. The theoretical results are confirmed by several numerical experiments with low- and high-order IgA spaces.

  2. Principal Component Analysis reveals correlation of cavities evolution and functional motions in proteins.

    Science.gov (United States)

    Desdouits, Nathan; Nilges, Michael; Blondel, Arnaud

    2015-02-01

    Protein conformation has been recognized as the key feature determining biological function, as it determines the position of the essential groups specifically interacting with substrates. Hence, the shape of the cavities or grooves at the protein surface appears to drive those functions. However, only a few studies describe the geometrical evolution of protein cavities during molecular dynamics simulations (MD), usually with a crude representation. To unveil the dynamics of cavity geometry evolution, we developed an approach combining cavity detection and Principal Component Analysis (PCA). This approach was applied to four systems subjected to MD (lysozyme, sperm whale myoglobin, Dengue envelope protein and EF-CaM complex). PCA on cavities allows us to perform efficient analysis and classification of the geometry diversity explored by a cavity. Additionally, it reveals correlations between the evolutions of the cavities and structures, and can even suggest how to modify the protein conformation to induce a given cavity geometry. It also helps to perform fast and consensual clustering of conformations according to cavity geometry. Finally, using this approach, we show that both carbon monoxide (CO) location and transfer among the different xenon sites of myoglobin are correlated with few cavity evolution modes of high amplitude. This correlation illustrates the link between ligand diffusion and the dynamic network of internal cavities.

  3. An SAO-based approach to technology evolution analysis using patent information: Case study—graphene sensors

    Institute of Scientific and Technical Information of China (English)

    Zhengyin; HU; Shu; FANG; Ling; WEI; Yi; WEN; Xian; ZHANG; Min; WANG

    2015-01-01

    Purpose: This paper introduces an approach to technology evolution analysis using patent information based on Subject-Action-Object(SAO) structures.Design/methodology/approach: First, SAO structures were extracted from patent documents and were cleaned. Second, several dimension-reduction techniques were used to generate technology topics. Then, the hierarchical relationships between technology topics were calculated based on patent clustering. Finally, technology evolution maps were drawn by adding a timeline.Findings: This approach can reveal technology evolution processes from multiple perspectives than other approaches.Research limitations: The semantic annotation of an SAO type is not very accurate and the semantic types of technology topics need to be enriched.Practical implications: The approach can be applied to draw technology evolution maps using different types of technology topics such as problem or solution.Originality/value: This approach offers an analytical dimension and more details than existing techniques, and it helps identify fundamental and emerging technologies more accurately and comprehensively.

  4. In Situ Observation of the Dislocation Structure Evolution During a Strain Path Change in Copper

    DEFF Research Database (Denmark)

    Wejdemann, Christian; Poulsen, Henning Friis; Lienert, Ulrich;

    2013-01-01

    The evolution of deformation structures in individual grains embedded in polycrystalline copper specimens during strain path changes is observed in situ by high-resolution reciprocal space mapping with high-energy synchrotron radiation. A large number of individual subgrains is resolved......; their behavior during the strain path change is revealed and complemented by the analysis of radial x-ray peak profiles for the entire grain. This allows distinction between two different regimes during the mechanically transient behavior following the strain path change: Below 0.3% strain, the number...... and orientation of the resolved subgrains change only slightly, while their elastic stresses are significantly altered. This indicates the existence of a microplastic regime during which only the subgrains deform plastically and no yielding of the dislocation walls occurs. After reloading above 0.3% strain...

  5. Structural Analysis of Fungal Cerebrosides

    Directory of Open Access Journals (Sweden)

    Eliana eBarreto-Bergter

    2011-12-01

    Full Text Available Of the ceramide monohexosides (CMHs, gluco- and galactosylceramides are the main neutral glycosphingolipids expressed in fungal cells. Their structural determination is greatly dependent on the use of mass spectrometric techniques, including fast atom bombardment-mass spectrometry (FAB-MS, electrospray ionization (ESI-MS, and energy collision-induced dissociation mass spectrometry (ESI-MS/CID-MS. Nuclear magnetic resonance (NMR has also been used successfully. Such a combination of techniques, combined with classical analytical separation, such as HPTLC and column chromatography, has led to the structural elucidation of a great number of fungal CMHs. The structure of fungal CMH is conserved among fungal species and consists of a glucose or galactose residue attached to a ceramide moiety containing 9-methyl-4,8-sphingadienine with an amidic linkage to hydroxylated fatty acids, most commonly having 16 or 18 carbon atoms and unsaturation between C-3 and C-4. Along with their unique structural characteristics, fungal CMHs have a peculiar subcellular distribution and striking biological properties. Fungal cerebrosides were also characterized as antigenic molecules directly or indirectly involved in cell growth or differentiation in Schizophyllum commune, Cryptococcus neoformans, Pseudallescheria boydii, Candida albicans, Aspergillus nidulans, A.fumigatus and Colletotrichum gloeosporioides. Besides classical techniques for cerebroside (CMH analysis, we now describe new approaches, combining conventional TLC and mass spectrometry, as well as emerging technologies for subcellular localization and distribution of glycosphingolipids by SIMS and imaging MALDI TOF .

  6. 雪峰山早中生代构造演化:构造学和年代学分析木%Tectonic evolution of the Early Mesozoic Xuefengshan belt:Insights from structural analysis and geochronological constraints

    Institute of Scientific and Technical Information of China (English)

    褚杨; 林伟; Michel Faure; 王清晨

    2011-01-01

    In the center of the South China Block,in Hunan Province, the Xuefengshan Belt providesa well-exposed example of intracontinental orogens. Detail field observations indicate that the Xuefengshan Belt can be divided into: ( 1 ) the Western Outer Zone,characterized by km-scale box-fold structure; (2) the Central Xuefengshan Zone, where the dip of the cleavage surface exhibits a fan-like pattern, separated from the Western Outer Zone by the Xuefengshan Main Thrust,the most deformed and metamorphosed region in this belt; (3)and the Eastern Zone,deformed mainly in the brittle-ductile level, characterized by top-to-the-NW structures and also some back-folding structures. The Xuefengshan Belt results of polyphase deformation: D1,characterized by a widespread top-to-the-NW ductile shearing. D2 corresponds to a SE-directed back thrusting and folding event. D3 consists of upright folds with vertical cleavage and lineation. The tectonic evolution of the Early Mesozoic Xuefengshan Belt is possibly originated by the continental subduction in response to the northwest directed subduction of the Pacific plate.%雪峰山主体地处湖南省境内,位于华南板块的中心区域,是一条典型的陆内造山带.通过详细的野外地质观察,我们将其分为3个构造单元:西部外区,主要以大型箱状褶皱为主;中部区,与西部区以主逆冲断层相分隔,劈理发育呈扇状,是雪峰山构造带的核心区域,也是变质级别最深、变形最强的区域;东部区,变形集中在脆韧性区域之上,以极性北西构造为主,并有反向构造发育.研究区经历了3期构造变形:D1为上部指向北西的韧性剪切,广泛发育于整个区域;D2代表了一期反向褶皱一逆冲构造事件;D3则以水平挤压为主,形成了直立的褶皱、劈理和线理.雪峰山的构造演化表明华南板块东南缘古太平洋板块向北西方向的俯冲可能引发了早中生代的陆内俯冲造山过程.

  7. The structural, metamorphic and magmatic evolution of Mesoproterozoic orogens

    OpenAIRE

    Roberts, Nick M. W.; Slagstad, Trond; Viola, Giulio

    2015-01-01

    The Mesoproterozoic (1600–1000 Ma) is an Era of Earth history that has been defined in the literature as being quiescent in terms of both tectonics and the evolution of the biosphere and atmosphere (Holland, 2006, Piper, 2013b and Young, 2013). The ‘boring billion’ is an informal term that is given to a time period overlapping the Mesoproterozoic period, extending from 1.85 to 0.85 Ga (Holland, 2006). Orogenesis was not absent from this period however, with various continents featuring active...

  8. Microeconomic co-evolution model for financial technical analysis signals

    Science.gov (United States)

    Rotundo, G.; Ausloos, M.

    2007-01-01

    Technical analysis (TA) has been used for a long time before the availability of more sophisticated instruments for financial forecasting in order to suggest decisions on the basis of the occurrence of data patterns. Many mathematical and statistical tools for quantitative analysis of financial markets have experienced a fast and wide growth and have the power for overcoming classical TA methods. This paper aims to give a measure of the reliability of some information used in TA by exploring the probability of their occurrence within a particular microeconomic agent-based model of markets, i.e., the co-evolution Bak-Sneppen model originally invented for describing species population evolutions. After having proved the practical interest of such a model in describing financial index so-called avalanches, in the prebursting bubble time rise, the attention focuses on the occurrence of trend line detection crossing of meaningful barriers, those that give rise to some usual TA strategies. The case of the NASDAQ crash of April 2000 serves as an illustration.

  9. Transient evolution of the global mode in turbulent swirling jets: experiments and modal stability analysis

    CERN Document Server

    Rukes, Lothar; Paschereit, Oliver; Oberleithner, Kilian

    2016-01-01

    Modal linear stability analysis has proven very successful in the analysis of coherent structures of turbulent flows. Formally, it describes the evolution of a disturbance in the limit of infinite time. In this work we apply modal linear stability analysis to a turbulent swirling jet undergoing a control parameter transient. The flow undergoes a transition from a non-vortex breakdown state to a state with a strong recirculation bubble and the associated global mode. High-speed Particle Image Velocimetry (PIV) measurements are the basis for a local linear stability analysis of the temporarily evolving base flow. This analysis reveals that the onset of the global mode is strongly linked to the formation of the internal stagnation point. Several transition scenarios are discussed and the ability of a frequency selection criterion to predict the wavemaker location, frequency and growth rate of the global mode are evaluated. We find excellent agreement between the linear global mode frequency and the experimental ...

  10. Precambrian crustal evolution and Cretaceous–Palaeogene faulting in West Greenland: Structural analysis of the northern Nagssugtoqidian orogen, West Greenland: an example of complex tectonic patterns in reworked high-grade metamorphic terrains

    Directory of Open Access Journals (Sweden)

    Mazur, Stanislaw

    2006-12-01

    Full Text Available Structural analysis of the deeply eroded northern flank of the Palaeoproterozoic Nagssugtoqidian orogen shows marked regional variations in both the orientation and type of fabrics, as is characteristic of Precambrian high-grade terrains subjected to polyphase deformation. Here we investigate the relationship between strain, metamorphic grade, and the resulting structural patterns. The study area south of Aasiaat in West Greenland consists of amphibolite- togranulite-gradeArchaean orthogneisses and relatively thin supracrustal units. The regional foliation displays a WSW–ENE to SW–NE strike associated with steep to moderate dips towards the WNW or SSE. Lineation trends are WSW–ENE and generally plunge gently towards the WSW. Mesoscopic fold hinges are usually colinear with the regional lineation. A systematic change in the plunge of lineations occurs across the south-western part of the study area. Towards the south, the lineation plunge progressively increases, despite the generally uniform strike of foliation. This southward increase of lineation pitch is typically associated with the transition from L > S or L = S shape fabrics in rocks characterised by a low pitch, to S > L or S fabrics in the zone of moderate to high pitch. The structural patterns point to subdivision of the study area into a southern domain mostly characterised by S or S > L shape fabrics and a moderate to high angle of lineation pitch, and a northern domain showing L > S or L = S fabrics and low angles of lineation pitch. This subdivision corresponds well with the map scale boundary between granulite facies rocks in the south and amphibolite facies rocks farther north. The observed structural pattern may be explained by two alternative tectonic models: (1 northward indentation of the previously cooled granulite block into the rheologically weaker amphibolite domain, and (2 strain partitioning within a mid-crustal transpression zone. In model 2 the northern domain

  11. Transposon Insertions, Structural Variations, and SNPs Contribute to the Evolution of the Melon Genome.

    Science.gov (United States)

    Sanseverino, Walter; Hénaff, Elizabeth; Vives, Cristina; Pinosio, Sara; Burgos-Paz, William; Morgante, Michele; Ramos-Onsins, Sebastián E; Garcia-Mas, Jordi; Casacuberta, Josep Maria

    2015-10-01

    The availability of extensive databases of crop genome sequences should allow analysis of crop variability at an unprecedented scale, which should have an important impact in plant breeding. However, up to now the analysis of genetic variability at the whole-genome scale has been mainly restricted to single nucleotide polymorphisms (SNPs). This is a strong limitation as structural variation (SV) and transposon insertion polymorphisms are frequent in plant species and have had an important mutational role in crop domestication and breeding. Here, we present the first comprehensive analysis of melon genetic diversity, which includes a detailed analysis of SNPs, SV, and transposon insertion polymorphisms. The variability found among seven melon varieties representing the species diversity and including wild accessions and highly breed lines, is relatively high due in part to the marked divergence of some lineages. The diversity is distributed nonuniformly across the genome, being lower at the extremes of the chromosomes and higher in the pericentromeric regions, which is compatible with the effect of purifying selection and recombination forces over functional regions. Additionally, this variability is greatly reduced among elite varieties, probably due to selection during breeding. We have found some chromosomal regions showing a high differentiation of the elite varieties versus the rest, which could be considered as strongly selected candidate regions. Our data also suggest that transposons and SV may be at the origin of an important fraction of the variability in melon, which highlights the importance of analyzing all types of genetic variability to understand crop genome evolution.

  12. Superhydrophobic hierarchically structured surfaces in biology: evolution, structural principles and biomimetic applications.

    Science.gov (United States)

    Barthlott, W; Mail, M; Neinhuis, C

    2016-08-01

    A comprehensive survey of the construction principles and occurrences of superhydrophobic surfaces in plants, animals and other organisms is provided and is based on our own scanning electron microscopic examinations of almost 20 000 different species and the existing literature. Properties such as self-cleaning (lotus effect), fluid drag reduction (Salvinia effect) and the introduction of new functions (air layers as sensory systems) are described and biomimetic applications are discussed: self-cleaning is established, drag reduction becomes increasingly important, and novel air-retaining grid technology is introduced. Surprisingly, no evidence for lasting superhydrophobicity in non-biological surfaces exists (except technical materials). Phylogenetic trees indicate that superhydrophobicity evolved as a consequence of the conquest of land about 450 million years ago and may be a key innovation in the evolution of terrestrial life. The approximate 10 million extant species exhibit a stunning diversity of materials and structures, many of which are formed by self-assembly, and are solely based on a limited number of molecules. A short historical survey shows that bionics (today often called biomimetics) dates back more than 100 years. Statistical data illustrate that the interest in biomimetic surfaces is much younger still. Superhydrophobicity caught the attention of scientists only after the extreme superhydrophobicity of lotus leaves was published in 1997. Regrettably, parabionic products play an increasing role in marketing.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'. PMID:27354736

  13. Conservation of mRNA secondary structures may filter out mutations in Escherichia coli evolution

    OpenAIRE

    Chursov, Andrey; Frishman, Dmitrij; Shneider, Alexander

    2013-01-01

    Recent reports indicate that mutations in viral genomes tend to preserve RNA secondary structure, and those mutations that disrupt secondary structural elements may reduce gene expression levels, thereby serving as a functional knockout. In this article, we explore the conservation of secondary structures of mRNA coding regions, a previously unknown factor in bacterial evolution, by comparing the structural consequences of mutations in essential and nonessential Escherichia coli genes accumul...

  14. Visualization and Evolution of the Scientific Structure of Fuzzy Sets Research in Spain

    Science.gov (United States)

    Lopez-Herrera, A. G.; Cobo, M. J.; Herrera-Viedma, E.; Herrera, F.; Bailon-Moreno, R.; Jimenez-Contreras, E.

    2009-01-01

    Introduction: Presents the first bibliometric study on the evolution of the fuzzy sets theory field. It is specially focused on the research carried out by the Spanish community. Method. The CoPalRed software, for network analysis, and the co-word analysis technique are used. Analysis: Bibliometric maps showing the main associations among the…

  15. Tectonic evolution and mantle structure of the Caribbean

    NARCIS (Netherlands)

    van Benthem, S.; Govers, R.; Spakman, W.; Wortel, R.

    2013-01-01

    We investigate whether predictions of mantle structure from tectonic reconstructions are in agreement with a detailed tomographic image of seismic P wave velocity structure under the Caribbean region. In the upper mantle, positive seismic anomalies are imaged under the Lesser Antilles and Puerto Ric

  16. Evolution of climatic niche specialization: a phylogenetic analysis in amphibians.

    Science.gov (United States)

    Bonetti, Maria Fernanda; Wiens, John J

    2014-11-22

    The evolution of climatic niche specialization has important implications for many topics in ecology, evolution and conservation. The climatic niche reflects the set of temperature and precipitation conditions where a species can occur. Thus, specialization to a limited set of climatic conditions can be important for understanding patterns of biogeography, species richness, community structure, allopatric speciation, spread of invasive species and responses to climate change. Nevertheless, the factors that determine climatic niche width (level of specialization) remain poorly explored. Here, we test whether species that occur in more extreme climates are more highly specialized for those conditions, and whether there are trade-offs between niche widths on different climatic niche axes (e.g. do species that tolerate a broad range of temperatures tolerate only a limited range of precipitation regimes?). We test these hypotheses in amphibians, using phylogenetic comparative methods and global-scale datasets, including 2712 species with both climatic and phylogenetic data. Our results do not support either hypothesis. Rather than finding narrower niches in more extreme environments, niches tend to be narrower on one end of a climatic gradient but wider on the other. We also find that temperature and precipitation niche breadths are positively related, rather than showing trade-offs. Finally, our results suggest that most amphibian species occur in relatively warm and dry environments and have relatively narrow climatic niche widths on both of these axes. Thus, they may be especially imperilled by anthropogenic climate change.

  17. Evolution of the Magnetic Field Structure of the Crab Pulsar

    CERN Document Server

    Lyne, Andrew; Weltevrede, Patrick; Jordan, Christine; Stappers, Ben; Bassa, Cees; Kramer, Michael

    2013-01-01

    Pulsars are highly-magnetised rotating neutron stars and are well-known for the stability of their signature pulse shapes, allowing high-precision studies of their rotation. However, during the past 22 years, the radio pulse profile of the Crab pulsar has shown a steady increase in the separation of the main pulse and interpulse components at 0.62$^{\\rm o}\\pm$0.03$^{\\rm o}$ per century. There are also secular changes in the relative strengths of several components of the profile. The changing component separation indicates that the axis of the dipolar magnetic field, embedded in the neutron star, is moving towards the stellar equator. This evolution of the magnetic field could explain why the pulsar does not spin down as expected from simple braking by a rotating dipolar magnetic field.

  18. Tabletop imaging of structural evolutions in chemical reactions

    CERN Document Server

    Ibrahim, Heide; Beaulieu, Samuel; Schmidt, Bruno E; Thiré, Nicolas; Bisson, Éric; Hebeisen, Christoph T; Wanie, Vincent; Giguére, Mathieu; Kieffer, Jean-Claude; Sanderson, Joseph; Schuurman, Michael S; Légaré, François

    2014-01-01

    The introduction of femto-chemistry has made it a primary goal to follow the nuclear and electronic evolution of a molecule in time and space as it undergoes a chemical reaction. Using Coulomb Explosion Imaging we have shot the first high-resolution molecular movie of a to and fro isomerization process in the acetylene cation. So far, this kind of phenomenon could only be observed using VUV light from a Free Electron Laser [Phys. Rev. Lett. 105, 263002 (2010)]. Here we show that 266 nm ultrashort laser pulses are capable of initiating rich dynamics through multiphoton ionization. With our generally applicable tabletop approach that can be used for other small organic molecules, we have investigated two basic chemical reactions simultaneously: proton migration and C=C bond-breaking, triggered by multiphoton ionization. The experimental results are in excellent agreement with the timescales and relaxation pathways predicted by new and definitively quantitative ab initio trajectory simulations.

  19. Thermo-plastic finite element analysis for metal honeycomb structure

    Directory of Open Access Journals (Sweden)

    Ji Zhanling

    2013-01-01

    Full Text Available This paper deals with thermal-plastic analysis for the metal honeycomb structure. The heat transfer equation and thermal elastoplastic constitutive equation of a multilayer panel are established and studied numerically using ANSYS software. The paper elucidates that only the outer skin produces easily plastic deformation, and the outer skin still exists some residual stress and residual deformation after cooling. The dynamic evolution of plastic deformation and material performance degradation under high energy thermal load are revealed.

  20. The evolution of the plasmoidal structure in the pinched column in plasma focus discharge

    Science.gov (United States)

    Kubes, P.; Paduch, M.; Cikhardt, J.; Klir, D.; Kravarik, J.; Rezac, K.; Cikhardtova, B.; Kortanek, J.; Zielinska, E.

    2016-04-01

    In this paper, a description is provided of the evolution of the dense spherical-like structures—plasmoids—formed in the pinched column of the dense plasma focus at the current of 1 MA at the final phase of implosion of the deuterium plasma sheath and at the phase of evolution of instabilities both at the time of HXR and neutron production. At the stratification of the plasma column, the plasma injected to the dense structures from the axially neighboring regions forms small turbulences which increase first the toroidal structures, and finally generates a non-chaotic current plasmoidal structure with central maximal density. This spontaneous evolution supports the hypothesis of the spheromak-like model of the plasmoid and its sub-millimeter analogy, high-energy spot. These spots, also called nodules formed in the filamentary structure of the current can be a source of the energy capable of accelerating the fast charged particles.

  1. Shifting the Starspot Paradigm through Imaging Magnetic Structures and Evolution

    Science.gov (United States)

    Roettenbacher, Rachael M.

    Magnetism is present in stars across all masses and evolutionary states. For cool stars with a convective outer envelope, stellar magnetic fields are generated through complex interactions between the convective layer and radiative core due to rotation. Magnetism in cool stars fuels stellar activity, in particular as starspots. Using starspots as a proxy, this work concentrates on imaging stellar magnetism. With state-of-the-art observations and imaging techniques, I investigate shifting the spot paradigm of localized starspots blemishing an otherwise bright surface (analogous to the solar photosphere) to a surface hosting a widespread network of magnetically-suppressed convection. This network is capable of affecting measurements of fundamental stellar parameters, such as radius and temperature, leading to inaccurate mass and age estimates. To accomplish this shift, I use precision Kepler data and a light-curve inversion algorithm for studies of stellar differential rotation and starspot evolution. Additionally, with long-baseline interferometric data collected with the Michigan Infrared Combiner (MIRC) at Georgia State University's Center for High Angular Resolution Astronomy (CHARA) Array, I target the bright, spotted, giant primary stars of close binary (RS CVn) systems. For these stars, I combine interferometric detections with radial velocity data to measure orbital and stellar parameters, which are used in concert with long-term photometric light curves to observe ellipsoidal variations, measure gravity darkening, and isolate the starspot signatures. In direct imaging using the interferometric data, I observe a spotted RS CVn star through an entire rotation period to detect canonical starspots, a polar starspot, and globally-suppressed convection. The regions of magnetically-suppressed convection cover a large fraction of the surface, potentially impacting estimates of stellar parameters. The combination of these efforts provides a start to a new era of

  2. Structural Evolution of Human Recombinant alfaB-Crystallin under UV Irradiation

    DEFF Research Database (Denmark)

    Sugiyama, Masaaki; Fujii, Noriko; Morimoto, Yukio;

    2008-01-01

    External stresses cause certain proteins to lose their regular structure and aggregate. In order to clarify this abnormal aggregation process, a structural evolution of human recombinant aB-crystallin under UV irradiation was observed with in situ small-angle neutron scattering. The abnormal...

  3. Structure, function and evolution of topologically associating domains (TADs) at HOX loci.

    Science.gov (United States)

    Lonfat, Nicolas; Duboule, Denis

    2015-10-01

    Hox genes encode transcription factors necessary for patterning the major developing anterior to posterior embryonic axis. In addition, during vertebrate evolution, various subsets of this gene family were co-opted along with the emergence of novel body structures, such as the limbs or the external genitalia. The morphogenesis of these axial structures thus relies in part upon the precisely controlled transcription of specific Hox genes, a mechanism involving multiple long-range enhancers. Recently, it was reported that such regulatory mechanisms were largely shared between different developing tissues, though with some specificities, suggesting the recruitment of ancestral regulatory modalities from one tissue to another. The analysis of chromatin architectures at HoxD and HoxA loci revealed the existence of two flanking topologically associating domains (TADs), precisely encompassing the adjacent regulatory landscapes. Here, we discuss the function of these TADs in the control of Hox gene regulation and we speculate about their capacity to serve as structural frameworks for the emergence of novel enhancers. In this view, TADs may have been used as genomic niches to evolve pleiotropic regulations found at many developmental loci. PMID:25913784

  4. Natural evolution inspired design of light trapping structure in thin film organic solar cells

    Science.gov (United States)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-09-01

    Light trapping has been developed to effectively enhance the efficiency of the thin film solar cell by extending the pathlength for light interacting with the active materials. Searching for optimal light trapping design requires a delicate balance among all the competing physical processes, including light refraction, reflection, and absorption. The existing design methods mainly depend on engineers' intuition to predefine the topology of the light-trapping structure. However, these methods are not capable of handling the topological variation in reaching the optimal design. In this work, a systematic approach based on Genetic Algorithm is introduced to design the scattering pattern for effective light trapping. Inspired by natural evolution, this method can gradually improve the performance of light trapping structure through iterative procedures, producing the most favorable structure with minimized reflection and substantial enhancement in light absorption. Both slot waveguide based solar cell and a more realistic organic solar with a scattering layer consisting of nano-scale patterned front layer is optimized to maximize absorption by strongly coupling incident sun light into the localized photonic modes supported by the multilayer system. Rigorous coupled wave analysis (RCWA) is implemented to evaluate the absorbance. The optimized slot waveguide cell achieves a broadband absorption efficiency of 48.1% and more than 3-fold increase over the Yablonovitch limit and the optimized realistic organic cell exhibits nearly 50% average absorbance over the solar spectrum with short circuit current density five times larger than the control case using planar ITO layer.

  5. Structure evolution of carbon black under ionic-liquid-assisted microwave irradiation

    International Nuclear Information System (INIS)

    The interactions between the carbon black (CB) and the ionic liquid (IL), 1-butyl-3-methyl-imiazolium hexafluorophosphate ([BMIM+][PF6-]), are firstly examined. The CB, mixed with the IL via simple blending, is then subjected to microwave (MW) irradiation to prepare the modified CB. The structure evolutions of the modified CB such as the microcrystalline structure and surface chemistry are revealed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and pore analysis. After mixing but before MW irradiation, the microcrystalline arrangement of CB turns to be more ordering and microcrystalline size (La) to be a little bigger but with a limited degree. Under MW irradiation, the IL undergoes severe decomposition. The combination of localized high temperature (proposed to be higher than 425 deg. C) and the decomposition of the IL leads to substantial structure changes of the CB. The graphitization of the CB surface, the disordering of the microcrystalline and the decrease in La are disclosed. In addition, compared with the untreated CB, the CB treated with IL-assisted MW irradiation is found to have much higher volume of the smaller mesopore.

  6. The importance of inherited structures in slope evolution: the Ridnaun Valley case, Italy

    Science.gov (United States)

    Zorzi, L.; Flaim, L.; Massironi, M.; Genevois, R.; Stead, D.

    2013-12-01

    The south facing slope of the Ridnaun Valley (South Tyrol, Italy) comprises the crystalline units belonging to the Austoalpine Nappe of the Alpine orogenic wedge and shows evidence of quaternary gravitational evolution which is highly dependent on the interaction between the slope trend and the brittle/ductile structural setting. The slope valley is incised within the paragneiss rocks of the Oetztal - Stubei Unit and the micaschists of the Schneeberg Unit. These two units are separated by a NNW gentle dipping tectonic contact, which obliquely intersects the E-W slope, and is characterized by multiple ultracataclasitic layers that follow the regional low angle north-dipping schistosity. Folds with sub-horizontal E-trending axes induce a change in the dip direction of the regional schistosity from N dipping (unfavorable to the slip) to SE dipping (favorable to the slip). NNE-SSW and N-S trending faults, having a mean thickness of incoherent fault breccias of 1 m, affect the entire slope. These along with the folds and the ultracataclastic layers, have significant influence on rock mass mechanical properties and on mechanisms and timing of the observed gravitational phenomena. Field work and ALS-HRDEM analysis has revealed different gravitational movements along the slope. A fully evolved gravitational collapse, having the features of a Rock Avalanche (RA), characterizes the central part covering an area of about 2.4 km2; whereas to the east and west of the RA, deep seated gravitational slope deformations (DSGSDs) still affect the slope. An ongoing gravitational deformation is apparent in the uphill sections of the slope, next to the crown area of the RA. PS and DS - SAR interferometry data (provided by the Geological Survey of the Autonomous Province of Bolzano, Italy), testify an ongoing movement on both the DSGSDs bordering the RA, highlighting a most unstable area at the western sector. The heterogeneous behavior of the slope is most likely controlled by the

  7. Design of structurally distinct proteins using strategies inspired by evolution.

    Science.gov (United States)

    Jacobs, T M; Williams, B; Williams, T; Xu, X; Eletsky, A; Federizon, J F; Szyperski, T; Kuhlman, B

    2016-05-01

    Natural recombination combines pieces of preexisting proteins to create new tertiary structures and functions. We describe a computational protocol, called SEWING, which is inspired by this process and builds new proteins from connected or disconnected pieces of existing structures. Helical proteins designed with SEWING contain structural features absent from other de novo designed proteins and, in some cases, remain folded at more than 100°C. High-resolution structures of the designed proteins CA01 and DA05R1 were solved by x-ray crystallography (2.2 angstrom resolution) and nuclear magnetic resonance, respectively, and there was excellent agreement with the design models. This method provides a new strategy to rapidly create large numbers of diverse and designable protein scaffolds.

  8. On the formation and evolution of gaseous structures in Comet P/Halley

    Science.gov (United States)

    Schulz, Rita; A'Hearn, Michael F.; Samarasinha, Nalin H.

    1993-01-01

    The possibility of a dynamic connection between the CN jets and CN shells in the coma of Comet P/Halley is here investigated through numerical simulations on the spatial and temporal evolution of gaseous jets. The evolution of such a jet into a shell is found to be straightforward for several geometries. It is noted that a closed shell structure may be due to a near-equatorial observational view of material derived from the active region near the nucleus equator.

  9. From fast to slow processes in the evolution of urban and regional settlement structures

    OpenAIRE

    Wolfgang Weidlich

    1999-01-01

    Complex systems consist of many intertwined organizational levels starting from micro-structures and ending with macrostructures. Their evolution takes place on different time scales: Micropatterns exhibit a fast dynamics whereas macropatterns develop slowly. Urban and regional science can make use of this fact by constructing a hierarchy of models on different spatio-temporal scales.Based on this understanding two models are presented: One for the relatively fast urban evolution on the micro...

  10. Geodynamic evolution and morphostructural analysis of the Western sector of the Russian Arctic shelf

    Directory of Open Access Journals (Sweden)

    Sorokhtin N. O.

    2016-03-01

    Full Text Available The paper considers issues of the Barents Sea shelf geodynamic evolution and influence of basement geologic structural processes on seabed morphology in their interaction. The obtained data have made possible to assume that the Norwegian-Mezenskaya rift system, Voronin graben, St. Anne and Victoria grabens were formed at the expense of the lithosphere stretching processes, but the Vostochno-Barentsevomorskaya basin and Medvezinsko-Edzinskaya area of depressions developed on the initial stage of lithosphere plate evolution due to collision of several island arcs and now all of them are outliers of the ancient oceanic crust. The technique of morphostructural analysis developed by the authors has allowed solve the inverse problem, and under morphological approach split all largest depressions on two main genetic types that confirm received geodynamic conclusion

  11. The tRNA Elbow in Structure, Recognition and Evolution

    Directory of Open Access Journals (Sweden)

    Jinwei Zhang

    2016-01-01

    Full Text Available Prominent in the L-shaped three-dimensional structure of tRNAs is the “elbow” where their two orthogonal helical stacks meet. It has a conserved structure arising from the interaction of the terminal loops of the D- and T-stem-loops, and presents to solution a flat face of a tertiary base pair between the D- and T-loops. In addition to the ribosome, which interacts with the elbow in all three of its tRNA binding sites, several cellular RNAs and many proteins are known to recognize the elbow. At least three classes of non-coding RNAs, namely 23S rRNA, ribonuclease P, and the T-box riboswitches, recognize the tRNA elbow employing an identical structural motif consisting of two interdigitated T-loops. In contrast, structural solutions to tRNA-elbow recognition by proteins are varied. Some enzymes responsible for post-transcriptional tRNA modification even disrupt the elbow structure in order to access their substrate nucleotides. The evolutionary origin of the elbow is mysterious, but, because it does not explicitly participate in the flow of genetic information, it has been proposed to be a late innovation. Regardless, it is biologically essential. Even some viruses that hijack the cellular machinery using tRNA decoys have convergently evolved near-perfect mimics of the tRNA elbow.

  12. Heterogeneous Deployment Analysis for Cost-Effective Mobile Network Evolution

    DEFF Research Database (Denmark)

    Coletti, Claudio

    2013-01-01

    statistical models of deployment areas, the performance analysis is carried out in the form of operator case studies for large-scale deployment scenarios, including realistic macro network layouts and inhomogeneous spatial traffic distributions. Deployment of small cells is performed by means of proposed...... network coverage and boosting network capacity in traffic hot-spot areas. The thesis deals with the deployment of both outdoor small cells and indoor femto cells. Amongst the outdoor solution, particular emphasis is put on relay base stations as backhaul costs can be reduced by utilizing LTE spectrum......The plethora of connected devices, such as attractive smartphones, data dongles and 3G/4G built-in tablet computers, has brought mobile operators to face increasing demand in mobile broadband traffic and services. In addition to the roll-out of Long Term Evolution (LTE), the deployment of small low...

  13. BASE-9: Bayesian Analysis for Stellar Evolution with nine variables

    Science.gov (United States)

    Robinson, Elliot; von Hippel, Ted; Stein, Nathan; Stenning, David; Wagner-Kaiser, Rachel; Si, Shijing; van Dyk, David

    2016-08-01

    The BASE-9 (Bayesian Analysis for Stellar Evolution with nine variables) software suite recovers star cluster and stellar parameters from photometry and is useful for analyzing single-age, single-metallicity star clusters, binaries, or single stars, and for simulating such systems. BASE-9 uses a Markov chain Monte Carlo (MCMC) technique along with brute force numerical integration to estimate the posterior probability distribution for the age, metallicity, helium abundance, distance modulus, line-of-sight absorption, and parameters of the initial-final mass relation (IFMR) for a cluster, and for the primary mass, secondary mass (if a binary), and cluster probability for every potential cluster member. The MCMC technique is used for the cluster quantities (the first six items listed above) and numerical integration is used for the stellar quantities (the last three items in the above list).

  14. DPR analysis of microstructural evolution of ZnO ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nikolic, Z.M. [Faculty of Physics, Belgrade (Czechoslovakia); Pavlovic, V.B. [Faculty of Agriculture, Zemun (Czechoslovakia)

    2004-07-01

    It is well known that, due to their specific properties, ZnO - based materials are frequently used in electrotechnics and electronics. Since these properties are very much dependent on the microstructural state of material (grain size, pore size, grain and pore distribution), in this article systematic investigation of evolution of microstructural constituents occurred during sintering of ZnO has been performed by new digital pattern recognition method (DPR). Microstructure investigations of the influence of the sintering regime on microstructural development of ZnO ceramics were carried out, using the scanning electron microscope (SEM) digital pictures, their contour recognition and decomposition of digital image objects according to their gray scale intensity (automatic microstructural analysis). The obtained results enable to establish the sintering parameters, which are indispensable for processing of materials with advanced required properties. (orig.)

  15. Diagnostics and future evolution analysis of the two parametric models

    CERN Document Server

    Yang, Guang; Meng, Xinhe

    2016-01-01

    In this paper, we apply three diagnostics including $Om$, Statefinder hierarchy and the growth rate of perturbations into discriminating the two parametric models for the effective pressure with the $\\Lambda$CDM model. By using the $Om$ diagnostic, we find that both the model 1 and the model 2 can be hardly distinguished from each other as well as the $\\Lambda$CDM model in terms of 68\\% confidence level. As a supplement, by using the Statefinder hierarchy diagnostics and the growth rate of perturbations, we discover that not only can our two parametric models be well distinguished from $\\Lambda$CDM model, but also, by comparing with $Om$ diagnostic, the model 1 and the model 2 can be distinguished better from each other. In addition, we also explore the fate of universe evolution of our two models by means of the rip analysis.

  16. Total Lightning Characteristics and Electric Structure Evolution in a Hailstorm

    Institute of Scientific and Technical Information of China (English)

    ZHENG Dong; ZHANG Yijun; MENG Qing; LU Weitao; YI Xiaoyuan

    2009-01-01

    In this paper, total lightning data observed by SAFIR3000 3-D Lightning Locating System was combined with radar data to analyze characteristics of the lightning activity and electric structure of a hailstorm that occurred in Beijing on 31 May 2005. The results indicated that there were two active periods for the lightning activity during the hailstorm process. The hail shooting was found in the first period. After the end of the hail shooting, lightning frequency decreased suddenly. However, more active lightning activities occurred in the second period with lots of them appearing in the cloud anvil region. The peak of the lightning frequency came about 5 rain prior to the hail shooting. Only 6.16% of the total lightning was cloud-to-ground (CG) lightning, among which 20% had positive polarity. This percentage was higher than that in normal thunderstorms. In addition, heavier positive CG lightning discharge occurred before rather than after the hail shooting. In the stage of the hail shooting, the electric structure of the hailstorm was inverted, with the main negative charge region located around the -40℃ level and the main positive charge region around the -15℃ level. In addition, a weak negative charge region existed below the positive charge region transitorily. After the hail shooting, the electric structure underwent fast and persistent adjustments and became a normal tripole, with positive charge in the upper and lower levels and negative charge in the middle levels. However, the electric structure was tilted under the influence of the westerly wind in the middle and upper levels. The lightning activity and electric structure were closely related to the dynamic and microphysical processes of the hailstorm. It was believed that severe storms with stronger updrafts were more conducive to an inverted tripolar electric structure than normal thunderstorms, and the inverted distribution could then facilitate more positive CG lightning in the severe storms.

  17. A SIMPLE ANALYSIS OF THE GEOTECTONIC EVOLUTIONAL CHARACTERS OF TONGLIN AREA,ANHUI

    Institute of Scientific and Technical Information of China (English)

    SHAO; Yong-jun; PENG; Sheng-lin; LIU; Liang-ming

    2001-01-01

    Tonglin area is one of the areas where there exist many copper ore deposits.The geotectonic property has many titles.Most of geological scholars call it the lower Yangtze platform depression and divide the geotectonic stages into formation of basement,sedimentaion of cover and intreplate deformation.According to the diwa theory,this paper classifies it as the Jiangsu-Hubei geodepressional system of the Central China geodepressional region.According to the analysis of the features of structural layers,the geotectonic evolution of the region is divided into four stages: pre-geosyncline,geosyncline,platform and diwa.

  18. Quasar Evolution Driven by Galaxy Encounters in Hierarchical Structures

    CERN Document Server

    Menci, N; Fontana, A; Giallongo, E; Poli, F; Vittorini, V

    2003-01-01

    We link the evolution of the galaxies in the hierarchical clustering scenario with the changing accretion rates of cold gas onto the central massive black holes that power the quasars. We base on galaxy interactions as main triggers of accretion; the related scaling laws are taken up from Cavaliere & Vittorini (2000), and grafted to a semi-analytic code for galaxy formation. As a result, at high $z$ the protogalaxies grow rapidly by hierarchical merging; meanwhile, much fresh gas is imported and also destabilized, so the holes are fueled at their full Eddington rates. At lower $z$ the galactic dynamical events are mostly encounters in hierarchically growing groups; now the refueling peters out, as the residual gas is exhausted while the destabilizing encounters dwindle. So, with no parameter tuning other than needed for stellar observables, our model uniquely produces at $z>3$ a rise, and at $z\\lesssim 2.5 $ a decline of the bright quasar population as steep as observed. In addition, our results closely f...

  19. Building intuition of iron evolution during solar cell processing through analysis of different process models

    Science.gov (United States)

    Morishige, Ashley E.; Laine, Hannu S.; Schön, Jonas; Haarahiltunen, Antti; Hofstetter, Jasmin; del Cañizo, Carlos; Schubert, Martin C.; Savin, Hele; Buonassisi, Tonio

    2015-09-01

    An important aspect of Process Simulators for photovoltaics is prediction of defect evolution during device fabrication. Over the last twenty years, these tools have accelerated process optimization, and several Process Simulators for iron, a ubiquitous and deleterious impurity in silicon, have been developed. The diversity of these tools can make it difficult to build intuition about the physics governing iron behavior during processing. Thus, in one unified software environment and using self-consistent terminology, we combine and describe three of these Simulators. We vary structural defect distribution and iron precipitation equations to create eight distinct Models, which we then use to simulate different stages of processing. We find that the structural defect distribution influences the final interstitial iron concentration ([]) more strongly than the iron precipitation equations. We identify two regimes of iron behavior: (1) diffusivity-limited, in which iron evolution is kinetically limited and bulk [] predictions can vary by an order of magnitude or more, and (2) solubility-limited, in which iron evolution is near thermodynamic equilibrium and the Models yield similar results. This rigorous analysis provides new intuition that can inform Process Simulation, material, and process development, and it enables scientists and engineers to choose an appropriate level of Model complexity based on wafer type and quality, processing conditions, and available computation time.

  20. The (De-)evolution of Evolution Games: A Content Analysis of the Representation of Evolution Through Natural Selection in Digital Games

    Science.gov (United States)

    Leith, Alex P.; Ratan, Rabindra A.; Wohn, Donghee Yvette

    2016-04-01

    Given the diversity and complexity of education game mechanisms and topics, this article contributes to a theoretical understanding of how game mechanisms "map" to educational topics through inquiry-based learning. Namely, the article examines the presence of evolution through natural selection (ENS) in digital games. ENS is a fundamentally important and widely misunderstood theory. This analysis of ENS portrayal in digital games provides insight into the use of games in teaching ENS. Systematic database search results were coded for the three principles of ENS: phenotypic variation, differential fitness, and fitness heritability. Though thousands of games use the term evolution, few presented elements of evolution, and even fewer contained all principles of ENS. Games developed to specifically teach evolution were difficult to find through Web searches. These overall deficiencies in ENS games reflect the inherent incompatibility between game control elements and the automatic process of ENS.

  1. The (De-)evolution of Evolution Games: A Content Analysis of the Representation of Evolution Through Natural Selection in Digital Games

    Science.gov (United States)

    Leith, Alex P.; Ratan, Rabindra A.; Wohn, Donghee Yvette

    2016-08-01

    Given the diversity and complexity of education game mechanisms and topics, this article contributes to a theoretical understanding of how game mechanisms "map" to educational topics through inquiry-based learning. Namely, the article examines the presence of evolution through natural selection (ENS) in digital games. ENS is a fundamentally important and widely misunderstood theory. This analysis of ENS portrayal in digital games provides insight into the use of games in teaching ENS. Systematic database search results were coded for the three principles of ENS: phenotypic variation, differential fitness, and fitness heritability. Though thousands of games use the term evolution, few presented elements of evolution, and even fewer contained all principles of ENS. Games developed to specifically teach evolution were difficult to find through Web searches. These overall deficiencies in ENS games reflect the inherent incompatibility between game control elements and the automatic process of ENS.

  2. Structure and tectonic evolution of the northeastern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ramana, M.V.; Krishna, K.S.; Ramprasad, T.; Desa, M.; Subrahmanyam, V.; Sarma, K.V.L.N.S.

    , (3) identification of the Cretaceous magnetic smooth zone and the boundary of the late Cretaceous crust in the distal part of the Bengal Fan, (4) structure and origin of the 85 degrees E Ridge, seismic stratigraphy, the presence of carbonate buildup...

  3. Structural constraints on the evolution of the collagen fibril: convergence on a 1014-residue COL domain.

    Science.gov (United States)

    Slatter, David Anthony; Farndale, Richard William

    2015-05-01

    Type I collagen is the fundamental component of the extracellular matrix. Its α1 gene is the direct descendant of ancestral fibrillar collagen and contains 57 exons encoding the rod-like triple-helical COL domain. We trace the evolution of the COL domain from a primordial collagen 18 residues in length to its present 1014 residues, the limit of its possible length. In order to maintain and improve the essential structural features of collagen during evolution, exons can be added or extended only in permitted, non-random increments that preserve the position of spatially sensitive cross-linkage sites. Such sites cannot be maintained unless the twist of the triple helix is close to 30 amino acids per turn. Inspection of the gene structure of other long structural proteins, fibronectin and titin, suggests that their evolution might have been subject to similar constraints.

  4. Correlation between atomic structure evolution and strength in a bulk metallic glass at cryogenic temperature.

    Science.gov (United States)

    Tan, J; Wang, G; Liu, Z Y; Bednarčík, J; Gao, Y L; Zhai, Q J; Mattern, N; Eckert, J

    2014-01-01

    A model Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) is selected to explore the structural evolution on the atomic scale with decreasing temperature down to cryogenic level using high energy X-ray synchrotron radiation. We discover a close correlation between the atomic structure evolution and the strength of the BMG and find out that the activation energy increment of the concordantly atomic shifting at lower temperature is the main factor influencing the strength. Our results might provide a fundamental understanding of the atomic-scale structure evolution and may bridge the gap between the atomic-scale physics and the macro-scale fracture strength for BMGs. PMID:24469299

  5. Structural Evolution of the Gold-rich Ashanti Belt, SW Ghana

    OpenAIRE

    Perrouty, Stephane

    2012-01-01

    The Paleoproterozoic Ashanti Belt hosts numerous world class gold deposits such as the Obuasi deposit (60 million ounces) and the Tarkwa deposit (40 million ounces). Characterising the regional structural and magmatic evolution provides new insight into the geotectonic context forming these deposits. In this work, we propose (1) a new geologic and structural map of the area using field observations and airborne geophysical data, (2) a structural context of early gold mineralisation in the Was...

  6. Fluorous 'ponytails' lead to strong gelators showing thermally induced structure evolution.

    Science.gov (United States)

    Kumari, Harshita; Armitage, Sarah E; Kline, Steven R; Damodaran, Krishna K; Kennedy, Stuart R; Atwood, Jerry L; Steed, Jonathan W

    2015-11-21

    Appending perfluoroalkyl substituents to bis(urea) gelators results in significantly decreased inter-chain interactions with markedly thinner fibres and hence more cross-linked and more transparent gels with potential applications in the crystallisation of fluorinated pharmaceuticals. Gel structure has been probed by detailed SANS measurements which indicate a surprising structure evolution on thermal cycling, not seen for hydrocarbon analogues. The SANS data are complemented by the single crystal X-ray structure of one fluorinated gelator. PMID:26364926

  7. Directed enzyme evolution guided by multidimensional analysis of substrate-activity space.

    Science.gov (United States)

    Larsson, Anna-Karin; Emrén, Lars O; Bardsley, William G; Mannervik, Bengt

    2004-01-01

    The directed evolution of protein function frequently involves identification of mutants with improved properties from a population of variants obtained by mutagenesis. The selection of clones to parent the subsequent generation is crucial to the continued creation of superior progeny. In the present study, multivariate analysis guided the evolution of human glutathione transferase (GST) T1-1 to 65-fold enhanced alkyltransferase activity. Six alternative substrates monitored the substrate-activity space that characterized a mutant library of enzymes, obtained by recombination of DNA and heterologous expression in Escherichia coli. A subset of mutants was identified by their proximity in the targeted region of six-dimensional factor space. DNA from these mutants was recombined to create a new generation of GST variants from which an improved enzyme was isolated. The multidimensional cluster analysis is applicable to quantitative properties in any population of molecules undergoing evolution and can guide the tailoring of proteins, nucleic acids and other chemical structures to novel and improved functions.

  8. Risk Analysis of Marine Structures

    DEFF Research Database (Denmark)

    Hansen, Peter Friis

    1998-01-01

    Basic concepts of risk analysis is introduced. Formulation and analysis of fault and event trees are treated.......Basic concepts of risk analysis is introduced. Formulation and analysis of fault and event trees are treated....

  9. Subsurface defects structural evolution in nano-cutting of single crystal copper

    Science.gov (United States)

    Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Sun, Yazhou; Guo, Yongbo; Liang, Yingchun

    2015-07-01

    In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, "V-shaped" dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated.

  10. Structural evolution of an alkali sulfate activated slag cement

    Science.gov (United States)

    Mobasher, Neda; Bernal, Susan A.; Provis, John L.

    2016-01-01

    In this study, the effect of sodium sulfate content and curing duration (from fresh paste up to 18 months) on the binder structure of sodium sulfate activated slag cements was evaluated. Isothermal calorimetry results showed an induction period spanning the first three days after mixing, followed by an acceleration-deceleration peak corresponding to the formation of bulk reaction products. Ettringite, a calcium aluminium silicate hydrate (C-A-S-H) phase, and a hydrotalcite-like Mg-Al layered double hydroxide have been identified as the main reaction products, independent of the Na2SO4 dose. No changes in the phase assemblage were detected in the samples with curing from 1 month up to 18 months, indicating a stable binder structure. The most significant changes upon curing at advanced ages observed were growth of the AFt phase and an increase in silicate chain length in the C-A-S-H, resulting in higher strength.

  11. Differential human capital and structural evolution in agriculture

    OpenAIRE

    Rogers, John L.

    1994-01-01

    The growth of market capitalism and the technological advances of the last two centuries underlie the relentless process of structural change in agriculture. Substantial occupational migration out of farming and geographical migration from rural to urban areas is a characteristic of most, if not all, economies in the 20th century. The process of rural-urban migration, and the resulting urban problems have received considerable attention. The fate of the residual farm population has received l...

  12. Structured habitats and the evolution of anticompetitor toxins in bacteria.

    OpenAIRE

    Chao, L.; Levin, B R

    1981-01-01

    We demonstrate that in liquid cultures, defined in this study as a mass habitat, the outcome of competition between Escherichia coli that produce an antibacterial toxin (colicin) and sensitive E. coli is frequency dependent; the colicinogenic bacteria are at an advantage only when fairly common (frequencies in excess of 2 X 10(-2)). However, we also show that in a soft agar matrix, a structured habitat, the colicinogenic bacteria have an advantage even when initially rare (frequencies as low ...

  13. Evolution of organizational structure and strategy of the automobile industry

    OpenAIRE

    Heng, S.H.; Wibbelink, R.

    2000-01-01

    This paper is a historically oriented study of the automobile industry. It sets out to understand why have the structure and strategy of the dominant companies in the automobile industry changed in the way they have done. Our findings suggest three factors at work, namely the knowledge of car production and of customers, the capability of the technological system, and the business environment. The knowledge system represents the level of know-how and the availability of information. In a sens...

  14. Effect of Ni on eutectic structural evolution in hypereutectic Al-Mg2Si cast alloys

    International Nuclear Information System (INIS)

    Research highlights: → By the injection of rod-like NiAl3 phase in Al-Mg2Si alloys, Al-Mg2Si binary eutectic structure gradually evolves into Al-Mg2Si-NiAl3 ternary eutectic. → The ternary eutectic presents a unique double rod structure that rod-like NiAl3 and Mg2Si uniformly distribute in Al matrix. → The mechanism of structural evolution was analyzed in terms of the detailed microstructural observations. → The high temperature (350 deg. C) tensile strength of the alloy increases by 23% due to the eutectic structural evolution. - Abstract: The aim of this work is to investigate the eutectic structural evolution of hypereutectic Al-20% Mg2Si with Ni addition under a gravity casting process. Three-dimensional morphologies of eutectic phases were observed in detail using field emission scanning electron microscopy, after Al matrix was removed by deep etching or extraction. The results show that Al-Mg2Si binary eutectic gradually evolves into Al-Mg2Si-NiAl3 ternary eutectic with the increase of Ni content, and flake-like eutectic Mg2Si transforms into rods. The ternary eutectic presents a unique double rod structure that rod-like NiAl3 and Mg2Si uniformly distribute in Al matrix. Further, the high temperature (350 deg. C) tensile strength of the alloy increases by 23% due to the eutectic structure evolution, and the mechanism of structural evolution was discussed and analyzed in terms of the detailed microstructural observations.

  15. Thermally Induced Structural Evolution and Performance of Mesoporous Block Copolymer-Directed Alumina Perovskite Solar Cells

    OpenAIRE

    Tan, Kwan Wee; Moore, David T.; Saliba, Michael; Sai, Hiroaki; Estroff, Lara A.; Hanrath, Tobias; Snaith, Henry J.; Wiesner, Ulrich

    2014-01-01

    Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI3–x Cl x ) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI3–x Cl x material evolution to be ...

  16. Correlation between atomic structure evolution and strength in a bulk metallic glass at cryogenic temperature

    OpenAIRE

    Tan, J.; Wang, G.; Z. Y. LIU; Bednarčík, J.; Gao, Yan; Zhai, Q. J.; Mattern, N.; Eckert, J.

    2014-01-01

    A model Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) is selected to explore the structural evolution on the atomic scale with decreasing temperature down to cryogenic level using high energy X-ray synchrotron radiation. We discover a close correlation between the atomic structure evolution and the strength of the BMG and find out that the activation energy increment of the concordantly atomic shifting at lower temperature is the main factor influencing the strength. Our res...

  17. THE GALACTIC STRUCTURE AND CHEMICAL EVOLUTION TRACED BY THE POPULATION OF PLANETARY NEBULAE

    International Nuclear Information System (INIS)

    Planetary nebulae (PNe) derive from the evolution of ∼1-8 Msun mass stars, corresponding to a wide range of progenitor ages, and thus are essential probes of the chemical evolution of galaxies, and indispensable to constrain the results from chemical models. We use an extended and homogeneous data set of Galactic PNe to study the metallicity gradients and the Galactic structure and evolution. The most up-to-date abundances, distances (calibrated with Magellanic Cloud PNe), and other parameters have been employed, together with a novel homogeneous morphological classification, to characterize the different PN populations. We confirm that morphological classes have a strong correlation with Peimbert's type PN, and also with their distribution on the Galactic landscape. We studied the α-element distribution within the Galactic disk, and found that the best selected disk population (i.e., excluding bulge and halo component), together with the most reliable PN distance scale yields to a radial oxygen gradient of Δlog(O/H)/ΔRG = -0.023 ± 0.006 dex kpc-1 for the whole disk sample, and of Δlog(O/H)/ΔRG = -0.035 ± 0.024, -0.023 ± 0.005, and -0.011 ± 0.013 dex kpc-1, respectively for Type I, II, and III PNe, i.e., for high-, intermediate-, and low-mass progenitors. Neon gradients for the same PN types confirm the trend. Accurate statistical analysis shows moderately high uncertainties in the slopes, but also confirms the trend of steeper gradient for PNe with more massive progenitors, indicating a possible steepening with time of the Galactic disk metallicity gradient for what the α-elements are concerned. We found that the metallicity gradients are almost independent on the distance scale model used, as long as these scales are equally well calibrated with the Magellanic Clouds. The PN metallicity gradients presented here are consistent with the local metallicity distribution; furthermore, oxygen gradients determined with young and intermediate age PNe show good

  18. Rogers' paradox recast and resolved: population structure and the evolution of social learning strategies.

    Science.gov (United States)

    Rendell, Luke; Fogarty, Laurel; Laland, Kevin N

    2010-02-01

    We explore the evolution of reliance on social and asocial learning using a spatially explicit stochastic model. Our analysis considers the relative merits of four evolved strategies, two pure strategies (asocial and social learning) and two conditional strategies (the "critical social learner," which learns asocially only when copying fails, and the "conditional social learner," which copies only when asocial learning fails). We find that spatial structure generates outcomes that do not always conform to the finding of earlier theoretical analyses that social learning does not enhance average individual fitness at equilibrium (Rogers' paradox). Although we describe circumstances under which the strategy of pure social learning increases the average fitness of individuals, we find that spatial structure introduces a new paradox, which is that social learning can spread even when it decreases the average fitness of individuals below that of asocial learners. We also show that the critical social learner and conditional social learner both provide solutions to the aforementioned paradoxes, although we find some conditions in which pure (random) social learning out-competes both conditional strategies. Finally, we consider the relative merits of critical and conditional social learning under various conditions.

  19. Stress field evolution law of mining environment reconstructing structure with change of filling height

    Institute of Scientific and Technical Information of China (English)

    CHEN Qing-fa; ZHOU Ke-ping; WANG Li-li

    2010-01-01

    For improving global stability of mining environment reconstructing structure,the stress field evolution law of the structure with the filling height change of low-grade backfill was studied by ADINA finite element analysis code.Three kinds of filling schemes were designed and calculated,in which the filling heights were 2,4,and 7 m,separately.The results show that there are some rules in the stress field with the increase of the filling height as follows:(1)the maximum value of tension stress of the roof decreases gradually,and stress conditions are improved gradually;(2)the tension stress status in the vertical pillar is transformed into the compressive stress status,and the carrying capacity is improved gradually; however,when the filling height is beyond 2.8 m,the carrying capacity of the vertical pillar grows very slowly,so,there is little significance to continue to fill the low-grade backfill;(3)the bottom pillar suffers the squeezing action from the vertical pillars at first and then the gravity action of the low-grade backfill,and the maximum value of tension stress of the bottom pillar firstly increases and then decreases.Considering the economic factor,security and other factors,the low-grade backfill has the most reasonable height(2.8 m)in the scope of all filling height.

  20. Time evolution of the structure function and dynamical scaling in porous SnO 2 dry gels

    Science.gov (United States)

    Craievich, A. F.; Santilli, C. V.; Pulcinelli, S. H.

    1995-05-01

    An in situ study of the structural evolution of a porous SnO2 dry gel, under isothermal conditions, was carried out by means of the SAXS technique. The time evolution of the structure function is in agreement with the predictions of computer simulations for advanced stages of phase separation in binary materials. Dynamical scaling properties of the structure function of the porous system were verified. This study suggests that the evolution of microporosity occurs by a pure coagulation mechanism.

  1. Robustness Analysis of Kinetic Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    The present paper considers robustness of kinetic structures. Robustness of structures has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. Especially for these types of structural syst...

  2. Thermally induced structural evolution and performance of mesoporous block copolymer-directed alumina perovskite solar cells.

    KAUST Repository

    Tan, Kwan Wee

    2014-04-11

    Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI(3-x)Cl(x)) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI(3-x)Cl(x) material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance.

  3. Modeling high temperature materials behavior for structural analysis

    CERN Document Server

    Naumenko, Konstantin

    2016-01-01

    This monograph presents approaches to characterize inelastic behavior of materials and structures at high temperature. Starting from experimental observations, it discusses basic features of inelastic phenomena including creep, plasticity, relaxation, low cycle and thermal fatigue. The authors formulate constitutive equations to describe the inelastic response for the given states of stress and microstructure. They introduce evolution equations to capture hardening, recovery, softening, ageing and damage processes. Principles of continuum mechanics and thermodynamics are presented to provide a framework for the modeling materials behavior with the aim of structural analysis of high-temperature engineering components.

  4. Structure evolution of poly(3-hexylthiophene) on Si wafer and poly(vinylphenol) sublayer.

    Science.gov (United States)

    Sun, Xiaoli; Ren, Zhongjie; Liu, Junteng; Takahashi, Isao; Yan, Shouke

    2014-07-01

    The structure evolution of P3HT thin films on Si wafer and PVPh covered Si wafer during heating, thermal annealing, and melt recrystallization processes has been studied in detail using X-ray analysis techniques. The effect of substrate on the crystallization behavior and interface structure of P3HT films was explored. For the P3HT films deposited on the Si substrate, it was found that the stability of P3HT crystals is orientation dependent. The crystals oriented with b-axis normal to the substrate, that is, a face-on molecular orientation, are less stable than those with the a-axis arranged normal to the substrate (side-on molecular orientation). Thermal annealing temperature plays an important role in the molecular structure of P3HT including crystal structure, film thickness, and surface roughness. After annealing at relatively high temperature, new crystals form during the cooling process accompanied by the shrinking of a-axis. Moreover, the melt recrystallization favors the formation of more stable P3HT crystals with side-on molecular orientation. The PVPh substrate does not affect the crystallization behavior of solution cast P3HT significantly but inhibits the formation of P3HT crystal with face-on molecular orientation. However, the interfacial morphology of P3HT and PVPh changes by annealing at elevated temperature. The P3HT/PVPh interface changes from a sharply defined one into a diffused one at around 160 °C. The PVPh sublayer inhibits the melt recrystallization of P3HT to some extent, leading to a slight expansion of the a-axis.

  5. Structure, function and evolution of the gas exchangers: comparative perspectives.

    Science.gov (United States)

    Maina, J N

    2002-10-01

    Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that 'necessity is the mother of invention', gas exchangers have been inaugurated through stiff cost-benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural-functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones of the modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices--water or air--within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animals have adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water-air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed. PMID:12430953

  6. Evolution in the enunciative structure of the political discourse

    Directory of Open Access Journals (Sweden)

    Joanna Jereczek-Lipińska

    2012-01-01

    Full Text Available This study is based upon discursive and logometric analysis of the political speeches delivered by the candidates during the campaign and pre-campaign phases of the 2012 presidential elections in France, taking into account the results of previous studies related to the 2007 presidential elections. The present paper aims at tracing the different representations of the speaker within his own speeches and at analyzing the way he verbalizes himself in his campaign by observing the use, the distribution, the role and the possible impact of “I” and of the other personal pronouns within the frame of political communication. The analysis of statistical data tends to emphasize syntactic as well as morphological, stylistic, lexical, and gramatical distinctive features of the speeches delivered by the candidates to the presidential elections, especially in relation with the new possibilities conveyed by internet.

  7. Structure evolution of AZ61 magnesium alloy in SIMA process

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; ZHANG Fa-yun; JIE Xiao-ping

    2005-01-01

    The effect of prior compressive deformation, isothermal temperature and holding time on the structure of AZ61 magnesium alloy fabricated by strain-induced melt activation(SIMA) processing was investigated. The specimens were subjected under deformation ratios of 0%, 22% and 40% and various heat treatment time and temperature regions. The results indicate that the ideal technological parameters of semi-solid AZ61 alloy produced with non-dendrites are recommended as 22% (prior compressive deformation), 595 ℃ (heat treatment temperature) and 40 min(time). The as-cast AZ61 magnesium alloy isn't fit for semi-solid forming.

  8. Review: Evolution of GnIH structure and function

    Directory of Open Access Journals (Sweden)

    Tomohiro eOsugi

    2014-08-01

    Full Text Available Discovery of gonadotropin-inhibitory hormone (GnIH in the Japanese quail in 2000 was the first to demonstrate the existence of a hypothalamic neuropeptide inhibiting gonadotropin release. We now know that GnIH regulates reproduction by inhibiting gonadotropin synthesis and release via action on the gonadotropin-releasing hormone (GnRH system and the gonadotrope in various vertebrates. GnIH peptides identified in birds and mammals have a common LPXRF-amide (X = L or Q motif at the C-terminus and inhibits pituitary gonadotropin secretion. However, the function and structure of GnIH peptides were diverse in fish. Goldfish GnIHs possessing a C-terminal LPXRF-amide motif had both stimulatory and inhibitory effects on gonadotropin synthesis or release. The C-terminal sequence of grass puffer and medaka GnIHs were MPQRF-amide. To investigate the evolutionary origin of GnIH and its ancestral structure and function, we searched for GnIH in agnathans, the most ancient lineage of vertebrates. We identified GnIH precursor gene and mature GnIH peptides with C-terminal QPQRF-amide or RPQRF-amide from the brain of sea lamprey. Lamprey GnIH fibers were in close proximity to GnRH-III neurons. Further, one of lamprey GnIHs stimulated the expression of lamprey GnRH-III peptide in the hypothalamus and gonadotropic hormone β mRNA expression in the pituitary. We further identified the ancestral form of GnIH, which had a C-terminal RPQRF-amide, and its receptors in amphioxus, the most basal chordate species. The amphioxus GnIH inhibited cAMP signaling in vitro. In sum, the original forms of GnIH may date back to the time of the emergence of early chordates. GnIH peptides may have had various C-terminal structures slightly different from LPXRF-amide in basal chordates, which had stimulatory and/or inhibitory functions on reproduction. The C-terminal LPXRF-amide structure and its inhibitory function on reproduction may be selected in later-evolved vertebrates, such as

  9. MADS-box gene evolution-structure and transcription patterns

    DEFF Research Database (Denmark)

    Johansen, Bo; Pedersen, Louise B; Skipper, Martin;

    2002-01-01

    from earlier analyses, and all major monophyletic groups are further supported by a common gene structure in exons 1-6 and by conserved C-terminal motifs. Transcription patterns are mapped on the tree to obtain an overview of MIKC gene transcription. Genes that are transcribed only in vegetative organs...... are located in the basal part of the tree, whereas genes involved in flower development have evolved later. As the universality of the ABC model has recently been questioned, special account is paid to the expression of A-, B-, and C-class genes. Mapping of transcription patterns on the phylogeny shows all...

  10. 一个锢囚状中尺度对流系统的多尺度结构分析%An analysis of the multi-scale structure and evolution of a meso-scale occluding convective system

    Institute of Scientific and Technical Information of China (English)

    易笑园; 李泽椿; 姚学祥; 王红艳; 孙晓磊

    2011-01-01

    The composite Doppler radar data at the Beijing, Tianjin and Qinhuangdao stations, the satellite data, the automatic meteorological observing stations data and the NCEP 1° × 1° reanalysis data were used to analyze the multi-scale structure and evolution of a meso-scale occluding convective system in the east part of the Huabei plain, which caused severe heavy rainfall on 18 July 2007. The methods of the meso-scale filtering, the 4DVAR single Doppler radar retrieval, and the horizontal and vertical section analyses were employed in this paper. The results show that firstly, this MaCS experienced 3 phases including the intialization and developing, the maturation and the dissipation. The cold cloud top of the MαCS changed from an elongated top to a circle one with only single center again to a polygon top with several centers as shown in the satellite images. It is seen from the radar data that a meso-scale convective system under the cold top was a occluding squall-line mesoscale convective system, whose two cross meso-β-scale line-squall convective systems were composed of several MγCSs arranged in the form of a line with independent strong radar reflectivity center and life-cycle. In the occluding phase of the MaCS the active MγCSs caused local severe rainfall. In the occluded phase, those MγCSs were closely organized together so as to make their edges become obscured with the occluded point corresponding to the cold cloud top center of the MαCS. In the dissipation phase, with the pattern of crossing disappearing and cloud top dropping, the radar echo-top and the reflectivity both showed an eddy feature. Secondly, severe ascending motion existed in the MαCS whose center appears from 600 hPa to 500 hPa. At the height of 200 hPa, an anti-cyclonic circulation had an effect on the shape of cold cloud top. At the height of 700 hPa, the cold air flow brought by the cyclonic circulation weakened physically the intensity of MαCS. Thirdly, the structure and

  11. Structure and Function Evolution of Thiolate Monolayers on Gold

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Grant Alvin [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    The use of n-alkanethiolate self-assembled monolayers on gold has blossomed in the past few years. These systems have functioned as models for common interfaces. Thiolate monolayers are ideal because they are easily modified before or after deposition. The works contained within this dissertation include interfacial characterization (inbred reflection absorption spectroscopy, ellipsometry, contact angle, scanning probe microscopy, and heterogeneous electron-transfer kinetics) and various modeling scenarios. The results of these characterizations present ground-breaking insights into the structure, function, and reproducible preparation of these monolayers. Surprisingly, three interfacial properties (electron-transfer, contact angle, and ellipsometry) were discovered to depend directly on the odd-even character of the monolayer components. Molecular modeling was utilized to investigate adlayer orientation, and suggests that these effects are adlayer structure specific. Finally, the electric force microscopy and theoretical modeling investigations of monolayer samples are presented, which show that the film dielectric constant, thickness, and dipole moment directly affect image contrast. In addition, the prospects for utilization of this emerging technique are outlined.

  12. Structure and function evolution of thiolate monolayers on gold

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Grant Alvin [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    The use of n-alkanethiolate self-assembled monolayers on gold has blossomed in the past few years. These systems have functioned as models for common interfaces. Thiolate monolayers are ideal because they are easily modified before or after deposition. The works contained within this dissertation include interfacial characterization (infrared reflection absorption spectroscopy, ellipsometry, contact angle, scanning probe microscopy, and heterogeneous electron-transfer kinetics) and various modeling scenarios. The results of these characterizations present ground-breaking insights into the structure, function, and reproducible preparation of these monolayers. Surprisingly, three interfacial properties (electron-transfer, contact angle, and ellipsometry) were discovered to depend directly on the odd-even character of the monolayer components. Molecular modeling was utilized to investigate adlayer orientation, and suggests that these effects are adlayer structure specific. Finally, the electric force microscopy and theoretical modeling investigations of monolayer samples are presented, which show that the film dielectric constant, thickness, and dipole moment directly affect image contrast. In addition, the prospects for utilization of this emerging technique are outlined.

  13. Impact origin of the Sudbury structure: Evolution of a theory

    Science.gov (United States)

    Lowman, Paul D., Jr.

    1992-01-01

    This paper reviews the origin, development, and present status of the widely accepted theory, proposed by Robert S. Dietz in 1962, that the Sudbury structure was formed by meteoritic or asteroidal impact. The impact theory for the origin of the Sudbury structure seems supported by a nearly conclusive body of evidence. However, even assuming an impact origin to be correct, at least three major questions require further study: (1) the original size and shape of the crater, before tectonic deformation and erosion; (2) the source of the melt now forming the Sudbury Igneous Complex; and (3) the degree, if any, to which the Ni-Cu-platinum group elements are meteoritic. The history of the impact theory illustrates several under-appreciated aspects of scientific research: (1) the importance of cross-fertilization between space research and terrestrial geology; (2) the role of the outsider in stimulating thinking by insiders; (3) the value of small science, at least in the initial stages of an investigation, Dietz's first field work having been at his own expense; and (4) the value of analogies (here, between the Sudbury Igneous Complex and the maria), which although incorrect in major aspects, may trigger research on totally new lines. Finally, the Sudbury story illustrates the totally unpredictable and, by implication, unplannable nature of basic research, in that insight to the origin of the world's then-greatest Ni deposit came from the study of tektites and the Moon.

  14. The evolution of field-induced structure of confined ferrofluid emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Mou, T.; Flores, G.A.; Liu, J. (California State Univ., Long Beach, CA (United States). Dept. of Physics and Astronomy); Bibette, J. (Centre de Recherche Paul Pascal, Pessac (France)); Richard, J. (Rhone-Poulenc Recherches, Aubervilliers (France))

    1994-09-01

    The authors report a real-time study of the evolution of the structure of confined ferrofluid emulsions during the ''liquid-solid'' phase transition. A monodisperse oil-in-water ferrofluid emulsion is used. The structure evolution of the emulsion after rapidly applying a magnetic field is probed by the static light scattering. The scattering pattern exhibits pronounced rings reflecting the formation of chains and their coalescence to columns or even ''worm'' structures. The scattering ring is found to decrease in size and brighten in intensity with time. To monitor the structure evolution in time, both the ring peak position in scattering wave vector, q[sub max], and the peak intensity, I[sub max], are measured as a function of time. Both q[sub max] and I[sub max] saturate in less than 0.5 seconds after applying a magnetic field. At a constant cell thickness of 25 [mu]m, the evolution of structure is essentially independent of volume fraction ranging from 0.015 to 0.13. In addition, a very good scaling is found in the scattered light intensity as a function of the scattering wave vector.

  15. Tectonic evolution and mantle structure of the Caribbean

    Science.gov (United States)

    Benthem, Steven; Govers, Rob; Spakman, Wim; Wortel, Rinus

    2013-06-01

    investigate whether predictions of mantle structure from tectonic reconstructions are in agreement with a detailed tomographic image of seismic P wave velocity structure under the Caribbean region. In the upper mantle, positive seismic anomalies are imaged under the Lesser Antilles and Puerto Rico. These anomalies are interpreted as remnants of Atlantic lithosphere subduction and confirm tectonic reconstructions that suggest at least 1100 km of convergence at the Lesser Antilles island arc during the past ~45 Myr. The imaged Lesser Antilles slab consists of a northern and southern anomaly, separated by a low-velocity anomaly across most of the upper mantle, which we interpret as the subducted North America-South America plate boundary. The southern edge of the imaged Lesser Antilles slab agrees with vertical tearing of South America lithosphere. The northern Lesser Antilles slab is continuous with the Puerto Rico slab along the northeastern plate boundary. This results in an amphitheater-shaped slab, and it is interpreted as westward subducting North America lithosphere that remained attached to the surface along the northeastern boundary of the Caribbean plate. At the Muertos Trough, however, material is imaged until a depth of only 100 km, suggesting a small amount of subduction. The location and length of the imaged South Caribbean slab agrees with proposed subduction of Caribbean lithosphere under the northern South America plate. An anomaly related to proposed Oligocene subduction at the Nicaragua rise is absent in the tomographic model. Beneath Panama, a subduction window exists across the upper mantle, which is related to the cessation of subduction of the Nazca plate under Panama since 9.5 Ma and possibly the preceding subduction of the extinct Cocos-Nazca spreading center. In the lower mantle, two large anomaly patterns are imaged. The westernmost anomaly agrees with the subduction of Farallon lithosphere. The second lower mantle anomaly is found east of

  16. Patterning and evolution of floral structures - marking time.

    Science.gov (United States)

    McKim, Sarah; Hay, Angela

    2010-08-01

    The diversity of flowering structures dazzles the eye, dominates the landscape, and invites evolutionary questions regarding the development of such variety. Comparative work in a number of genetically tractable plant species has addressed how diverse floral architectures develop, and started to reveal the balance between conservation and divergence of the patterning mechanisms responsible for when and where flowers form on a plant. We highlight findings from Petunia where conserved LFY/UFO function is under species-specific regulation, and a novel mechanism involving WOX homeodomain proteins for modulating cyme development in diverse nightshades. We also draw attention to recent findings in Arabidopsis of miRNA and chromatin-based timing mechanisms controlling floral development, and illustrate how genetic studies in Arabidopsis relatives can reveal how evolutionary changes in such mechanisms generate diversity in form. PMID:20452201

  17. Further Evidence for Cosmological Evolution of the Fine Structure Constant

    Energy Technology Data Exchange (ETDEWEB)

    Webb, J. K.; Murphy, M. T.; Flambaum, V. V.; Dzuba, V. A.; Barrow, J. D.; Churchill, C. W.; Prochaska, J. X.; Wolfe, A. M.

    2001-08-27

    We describe the results of a search for time variability of the fine structure constant {alpha} using absorption systems in the spectra of distant quasars. Three large optical data sets and two 21 cm and mm absorption systems provide four independent samples, spanning {approx}23% to 87% of the age of the universe. Each sample yields a smaller {alpha} in the past and the optical sample shows a 4{sigma} deviation: {Delta}{alpha}/{alpha}=-0.72{+-}0.18 x 10{sup -5} over the redshift range 0.5

  18. Halo formation and evolution: unification of structure and physical properties

    Science.gov (United States)

    Ernest, Allan D.; Collins, Matthew P.

    2016-08-01

    The assembly of matter in the universe proliferates a wide variety of halo structures, often with enigmatic consequences. Giant spiral galaxies, for example, contain both dark matter and hot gas, while dwarf spheroidal galaxies, with weaker gravity, contain much larger fractions of dark matter, but little gas. Globular clusters, superficially resembling these dwarf spheroidals, have little or no dark matter. Halo temperatures are also puzzling: hot cluster halos contain cooler galaxy halos; dwarf galaxies have no hot gas at all despite their similar internal processes. Another mystery is the origin of the gas that galaxies require to maintain their measured star formation rates (SFRs). We outline how gravitational quantum theory solves these problems, and enables baryons to function as weakly-interacting-massive-particles (WIMPs) in Lambda Cold Dark Matter (LCDM) theory. Significantly, these dark-baryon ensembles may also be consistent with primordial nucleosynthesis (BBN) and cosmic microwave background (CMB) anisotropies.

  19. Further Evidence for Cosmological Evolution of the Fine Structure Constant

    CERN Document Server

    Webb, J K; Flambaum, V V; Dzuba, V A; Barrow, John D; Churchill, C W; Prochaska, J X; Wolfe, A M

    2001-01-01

    We summarise the results of a search for time variability of the fine structure constant, alpha, using absorption systems in the spectra of distant quasars. Three large optical datasets and two 21cm/mm absorption systems provide four independent samples, spanning approximately 23% to 87% of the age of the universe. Each sample yields a negative Delta(alpha)/alpha (smaller alpha in the past) and the whole optical sample shows a 4-sigma deviation: Delta(alpha)/alpha = -0.72 +/- 0.18 x 10^{-5} over the redshift range 0.5 < z < 3.5. A comprehensive search for systematic effects reveals none which can explain our results. The only potentially significant systematic effects push Delta(alpha)/alpha towards positive values, i.e. our results would become more significant were we to correct for them.

  20. Fine structure of flare ribbons and evolution of electric currents

    CERN Document Server

    Sharykin, I N

    2014-01-01

    Emission of solar flares across the electromagnetic spectrum is often observed in the form of two expanding ribbons. The standard flare model explains the flare ribbons as footpoints of magnetic arcades, emitting due to interaction of energetic particles with the chromospheric plasma. However, the physics of this interaction and properties of the accelerated particles are still unknown. We present results of multiwavelength observations of C2.1 flare of August 15, 2013, observed with New Solar Telescope (NST) of Big Bear Solar Observatory, Solar Dynamics Observatory (SDO), GOES and FERMI spacecraft. The observations reveal previously unresolved sub-arcsecond structure of the flare ribbons in regions of strong magnetic field consisting from numerous small-scale bright knots. We observe red-blue asymmetry of H alpha flare ribbons with a width as small as 100 km. We discuss the relationship between the ribbons and vertical electric currents estimated from vector magnetograms, and show that Joule heating can be r...

  1. The structural evolution of carbonaceous material during metamorphism : a geothermometer

    Science.gov (United States)

    Beyssac, O.; Goffe, B.; Brunet, F.; Bollinger, L.; Avouac, J.; Rouzaud, J.

    2003-12-01

    With increasing metamorphic temperature, the organic matter present in sedimentary rocks is progressively transformed into graphite (graphitization). The degree of organization of this carbonaceous material (CM) as characterized by Raman spectroscopy (RSCM), can be used as a geothermometer which yields the maximum temperature reached during the metamorphic cycle (Beyssac et al., 2002). We used this RSCM geothermometer to map the maximum metamorphic temperatures through the Lesser Himalaya (LH) in Nepal. This study provides a large dataset (80 samples) to estimate uncertainty of this method and to ascertain its reliability by comparison with conventional petrological investigations. We show that the RSCM geothermometer might be used to detect inter-samples temperature variations as small as 10° C or so, but absolute temperatures are only loosely determined to +/- 50° C due to the uncertainty on the calibration. This successful application of the RSCM geothermometer confirms that, at the timescale of regional metamorphism (several My), the transformation of CM is mainly controlled by temperature. However, laboratory investigations suggest that, in addition to temperature, pressure should also play a role (Beyssac et al. 2003). As a matter of fact, high degree of organizations encountered in natural CM cannot be reproduced in laboratory without pressure, even at temperatures as high as 3000° C. In addition to the data acquired on natural CM, we will discuss laboratory experiments performed up to 8 GPa which show that (1) a few kbar of hydrostatic pressure are required to initiate microtextural and subsequent structural transformations within CM and (2) the overall effect of increasing pressure is to speed up graphitization process. Beyssac, O., Goffe, B., Chopin, C., and Rouzaud, J.N., 2002, Raman spectra of carbonaceous material in metasediments: a new geothermometer. Journal of Metamorphic Geology, 20, 859-871. Beyssac, O., Brunet, F., Petitet, J.P., Goffe, B

  2. THE FORMATION, EVOLUTION AND OPTIMAZATIONOF TERRITORIAL STRUCTURE IN THE SOUTHERN CHINA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With the change of geopolitical pattern of the world, pacific rim area increases economic cooperation, instead of military antagonism. After reform and open to outside world, the southern China takes in an amount of investment from Hongkong, Macao and Taiwan, taking advantage of superior geo-environment and thus forms a topical model of core-periphery in the southern China. The core-periphery model in the southern China is territorially made of three parts: core area-Hong Kong, Macao and Taiwan; peripherial area Zhujiang delta; second core area-parts of Hunan Province, Jiangxi Province, Fujian Province and Hainan Province and Cuangxi Zhnang Autonomous Region. Its evolutional stage of this model can be divided into four stages: (1) the stage of polarization of core area; (2) the stage of the second core area strongly controlled by core area; (3) the transitional stage of the second area; (4) the stage of the southern China space integrity. Taking the core-periphrial model in the southern China as an integrity of interrelational and rational division, its whole functional organized system is “input-product-assemble-output”, core area is mainly then as the managed and transported center, the second area plays a product and productive control function and becomes center of manufacturing, study and development, periphrial area constructs as the center of material and raw material and the base of agricultural and side-line products. Based on the analysis of the formative structure, evolutional law and the design of territorial function, we suggust the way of territerial optimazation as follows: (1) establishing the large hinterland which takes Xijiang basin as its core; (2) construct the high and renewed technological corridor; (3) constructing stable and varied material and raw material base; (4) reinforcing the organization and adjustment and managment between core area,periphrial area and second periphrial area. (5) constucting the varied corridor among core area

  3. A numerical model for the evolution of internal structure of cavitation cloud

    Science.gov (United States)

    Du, Tezhuan; Wang, Yiwei; Liao, Lijuan; Huang, Chenguang

    2016-07-01

    Bubble size distributions in cloud cavitation are important in cavitating flows. In this study, a numerical model was developed to study the evolution of the internal structure of cloud cavitation. The model includes (1) an evolution equation of bubble number density, which considers the bubble breakup effect and (2) the multiphase Reynolds-averaged Navier-Stokes equations with a modified cavitation model for background cavitating flows. The proposed model was validated with a flow over a projectile. Results show that the numerical model can predict the evolution of the internal structure of cloud cavitation. Comparisons of the proposed model and Singhal model were discussed. The effects of re-entrant jet and bubble number density on cavitating flows were also investigated.

  4. Kinematic Morphology of Large-scale Structure: Evolution from Potential to Rotational Flow

    CERN Document Server

    Wang, Xin; Aragon-Calvo, Miguel A; Neyrinck, Mark C; Eyink, Gregory L

    2013-01-01

    As an alternative way of describing the cosmological velocity field, we discuss the evolution of rotational invariants constructed from the velocity gradient tensor. Compared with the traditional divergence-vorticity decomposition, these invariants, defined as coefficients of characteristic equation of the velocity gradient tensor, enable a complete classification of all possible flow patterns in the dark-matter comoving frame, including both potential and vortical flows. Before shell-crossing, different categories of potential flow are highly associated with cosmic web structure, because of the coherent evolution of density and velocity. This correspondence is even preserved at some level when vorticity is generated after shell-crossing. The evolution from the potential to vortical flow can be traced continuously by these invariants. With the help of this tool, we show that the vorticity is generated in a particular way that is highly correlated with the large-scale structure. This includes a distinct spatia...

  5. Structure and Evolution of Mediterranean Forest Research: A Science Mapping Approach.

    Science.gov (United States)

    Nardi, Pierfrancesco; Di Matteo, Giovanni; Palahi, Marc; Scarascia Mugnozza, Giuseppe

    2016-01-01

    This study aims at conducting the first science mapping analysis of the Mediterranean forest research in order to elucidate its research structure and evolution. We applied a science mapping approach based on co-term and citation analyses to a set of scientific publications retrieved from the Elsevier's Scopus database over the period 1980-2014. The Scopus search retrieved 2,698 research papers and reviews published by 159 peer-reviewed journals. The total number of publications was around 1% (N = 17) during the period 1980-1989 and they reached 3% (N = 69) in the time slice 1990-1994. Since 1995, the number of publications increased exponentially, thus reaching 55% (N = 1,476) during the period 2010-2014. Within the thirty-four years considered, the retrieved publications were published by 88 countries. Among them, Spain was the most productive country, publishing 44% (N = 1,178) of total publications followed by Italy (18%, N = 482) and France (12%, N = 336). These countries also host the ten most productive scientific institutions in terms of number of publications in Mediterranean forest subjects. Forest Ecology and Management and Annals of Forest Science were the most active journals in publishing research in Mediterranean forest. During the period 1980-1994, the research topics were poorly characterized, but they become better defined during the time slice 1995-1999. Since 2000s, the clusters become well defined by research topics. Current status of Mediterranean forest research (20092014) was represented by four clusters, in which different research topics such as biodiversity and conservation, land-use and degradation, climate change effects on ecophysiological responses and soil were identified. Basic research in Mediterranean forest ecosystems is mainly conducted by ecophysiological research. Applied research was mainly represented by land-use and degradation, biodiversity and conservation and fire research topics. The citation analyses revealed highly

  6. Structure and Evolution of Mediterranean Forest Research: A Science Mapping Approach.

    Directory of Open Access Journals (Sweden)

    Pierfrancesco Nardi

    Full Text Available This study aims at conducting the first science mapping analysis of the Mediterranean forest research in order to elucidate its research structure and evolution. We applied a science mapping approach based on co-term and citation analyses to a set of scientific publications retrieved from the Elsevier's Scopus database over the period 1980-2014. The Scopus search retrieved 2,698 research papers and reviews published by 159 peer-reviewed journals. The total number of publications was around 1% (N = 17 during the period 1980-1989 and they reached 3% (N = 69 in the time slice 1990-1994. Since 1995, the number of publications increased exponentially, thus reaching 55% (N = 1,476 during the period 2010-2014. Within the thirty-four years considered, the retrieved publications were published by 88 countries. Among them, Spain was the most productive country, publishing 44% (N = 1,178 of total publications followed by Italy (18%, N = 482 and France (12%, N = 336. These countries also host the ten most productive scientific institutions in terms of number of publications in Mediterranean forest subjects. Forest Ecology and Management and Annals of Forest Science were the most active journals in publishing research in Mediterranean forest. During the period 1980-1994, the research topics were poorly characterized, but they become better defined during the time slice 1995-1999. Since 2000s, the clusters become well defined by research topics. Current status of Mediterranean forest research (20092014 was represented by four clusters, in which different research topics such as biodiversity and conservation, land-use and degradation, climate change effects on ecophysiological responses and soil were identified. Basic research in Mediterranean forest ecosystems is mainly conducted by ecophysiological research. Applied research was mainly represented by land-use and degradation, biodiversity and conservation and fire research topics. The citation analyses

  7. Structure and Evolution of Pre-Main Sequence Stars

    CERN Document Server

    Schulz, Norbert S; Bautz, Mark W; Canizares, Claude C; Davis, John; Dewey, Dan; Huenemoerder, David P; Heilmann, Ralf; Houck, John; Marshall, Herman L; Nowak, Mike; Schattenburg, Mark; Audard, Marc; Drake, Jeremy; Gagne, Marc; Kastner, Joel; Kallman, Tim; Lautenegger, Maurice; Lee, Julia; Miller, Jon; Montmerle, Thierry; Mukai, Koji; Osten, Rachel; Parerels, Frits; Pollock, Andy; Preibisch, Thomas; Raymond, John; Reale, Fabio; Smith, Randall; Testa, Paola; Weintraub, David

    2009-01-01

    Low-mass pre-main sequence (PMS) stars are strong and variable X-ray emitters, as has been well established by EINSTEIN and ROSAT observatories. It was originally believed that this emission was of thermal nature and primarily originated from coronal activity (magnetically confined loops, in analogy with Solar activity) on contracting young stars. Broadband spectral analysis showed that the emission was not isothermal and that elemental abundances were non-Solar. The resolving power of the Chandra and XMM X-ray gratings spectrometers have provided the first, tantalizing details concerning the physical conditions such as temperatures, densities, and abundances that characterize the X-ray emitting regions of young star. These existing high resolution spectrometers, however, simply do not have the effective area to measure diagnostic lines for a large number of PMS stars over required to answer global questions such as: how does magnetic activity in PMS stars differ from that of main sequence stars, how do they ...

  8. Kinematic Analysis of Tensegrity Structures

    OpenAIRE

    Whittier, William Brooks

    2002-01-01

    Tensegrity structures consist of isolated compression members (rigid bars) suspended by a continuous network of tension members (cables). Tensegrity structures can be used as variable geometry truss (VGT) mechanisms by actuating links to change their length. This paper will present a new method of position finding for tensegrity structures that can be used for actuation as VGT mechanisms. Tensegrity structures are difficult to understand and mathematically model. This difficulty is p...

  9. Structural Analysis of Steel Structures under Fire Loading

    Directory of Open Access Journals (Sweden)

    C. Crosti

    2009-01-01

    Full Text Available This paper focuses on the structural analysis of a steel structure under fire loading. In this framework, the objective is to highlight the importance of the right choice of analyses to develop, and of the finite element codes able to model the resistance and stiffness reduction due to the temperature increase. In addition, the evaluation of the structural collapse under fire load of a real building is considered, paying attention to the global behavior of the structure itself. 

  10. Thermal Structure and Radius Evolution of Irradiated Gas Giant Planets

    CERN Document Server

    Arras, P; Arras, Phil; Bildsten, Lars

    2006-01-01

    We consider the thermal structure and radii of strongly irradiated gas giant planets over a range in mass and irradiating flux. The cooling rate of the planet is sensitive to the surface boundary condition, which depends on the detailed manner in which starlight is absorbed and energy redistributed by fluid motion. We parametrize these effects by imposing an isothermal boundary condition $T \\equiv T_{\\rm deep}$ below the photosphere, and then constrain $T_{\\rm deep}$ from the observed masses and radii. We compute the dependence of luminosity and core temperature on mass, $T_{\\rm deep}$ and core entropy, finding that simple scalings apply over most of the relevant parameter space. These scalings yield analytic cooling models which exhibit power-law behavior in the observable age range $0.1-10 {\\rm Gyr}$, and are confirmed by time-dependent cooling calculations. We compare our model to the radii of observed transiting planets, and derive constraints on $T_{\\rm deep}$. Only HD 209458 has a sufficiently accurate ...

  11. FINE STRUCTURE OF FLARE RIBBONS AND EVOLUTION OF ELECTRIC CURRENTS

    International Nuclear Information System (INIS)

    Emission of solar flares across the electromagnetic spectrum is often observed in the form of two expanding ribbons. The standard flare model explains flare ribbons as footpoints of magnetic arcades, emitting due to interaction of energetic particles with the chromospheric plasma. However, the physics of this interaction and properties of the accelerated particles are still unknown. We present results of multiwavelength observations of the C2.1 flare of 2013 August 15, observed with the New Solar Telescope of the Big Bear Solar Observatory, and the Solar Dynamics Observatory, GOES, and Fermi spacecraft. The observations reveal previously unresolved sub-arcsecond structure of flare ribbons in regions of strong magnetic field consisting from numerous small-scale bright knots. We observe a red-blue asymmetry of Hα flare ribbons with a width as small as ∼100 km. We discuss the relationship between the ribbons and vertical electric currents estimated from vector magnetograms, and show that Joule heating can be responsible for energization of Hα knots in the ribbons

  12. Diverse Structural Evolution at z > 1 in Cosmologically Simulated Galaxies

    CERN Document Server

    Snyder, Gregory F; Moody, Christopher; Peth, Michael; Freeman, Peter; Ceverino, Daniel; Primack, Joel; Dekel, Avishai

    2014-01-01

    From mock Hubble Space Telescope images, we quantify non-parametric statistics of galaxy morphology, thereby predicting the emergence of relationships among stellar mass, star formation, and observed rest-frame optical structure at 1 10^10 M_sun contain relatively more disc-dominated light profiles than those with lower mass, reflecting significant disc brightening in some haloes at 1 10^10 M_sun. We analyze a cosmological major merger at z~1.5 and find that the newly proposed MID morphology diagnostics trace later stages while G-M20 trace earlier ones. MID is sensitive also to clumpy star-forming discs. The observability time of typical MID-enhanced events in our simulation sample is less than 100 Myr. A larger sample of cosmological assembly histories may be required to calibrate such diagnostics in the face of their sensitivity to viewing angle, segmentation algorithm, and various phenomena such as clumpy star formation and minor mergers.

  13. Structure and evolution of low-mass Population II stars

    Science.gov (United States)

    Montalbán, J.; D'Antona, F.; Mazzitelli, I.

    2000-08-01

    The focus of the present paper is on the detailed description of the internal structures of low mass, population II stars, to clarify some issues about these stellar models and, mainly, their present reliability for observational comparisons. We then explore 1) the role of the local convective model; 2) the differences between "grey" and "non grey" models, and between models in which the photospheric boundary conditions are set at different optical depths (τph = 3 or 100); 3) the role of the equation of state (EoS), both in the atmospheric models and in the interior. One of the major conclusions of the paper is a cautionary note about the usage of the additive volume law in EoS calculations. The dependence of the HR diagram locations and mass luminosity relations on metal and helium content are also discussed. A few comparisons with globular cluster stars show that: 1) general consistency of distance scales and morphologies in the HR diagram is found, when comparing ground based measurements in the Johnson B and V bands and observations in the HST bands; 2) a discrepancy between models and observations may exist for more metal rich clusters; 3) the plausible hypothesis that the mass function in the globular cluster NGC 6397 behaves smoothly until the lower limit of the main sequence poses constraints on the mass-luminosity relation at the lowest end of the main sequence. The evolutionary tracks are available at the WEB location http://www.mporzio.astro.it.

  14. Multidimensional analysis of Drosophila wing variation in Evolution Canyon

    Indian Academy of Sciences (India)

    Vincent Debat; Raphael Cornette; Abraham B. Koral; Eviatar Nevo; David Soulet; Jean R. David

    2008-12-01

    Environmental stress has been suggested to be a major evolutionary force, both through inducing strong selection and because of its direct impact on developmental buffering processes that alter the evolvability of organisms. In particular, temperature has attracted much attention because of its importance as an ecological feature and the relative ease with which it can be experimentally manipulated in the lab. Evolution Canyon, Lower Nahal Oren, Israel, is a well studied natural site where ecological parameters are suspected to drive evolutionary differentiation. In this study, using Drosophila melanogaster isofemale lines derived from wild flies collected on both slopes of the canyon, we investigated the effect of developmental temperature upon the different components of phenotypic variation of a complex trait: the wing. Combining geometric and traditional morphometrics, we find only limited evidence for a differentiation among slopes. Investigating simultaneously phenotypic plasticity, genetic variation among isofemale lines, variation among individuals and fluctuating asymmetry, we could not identify a consistent effect of the stressful conditions encountered on the south facing slope. The prevailing structuring effect is that of the experimentally manipulated temperature which clearly influences wing mean size and shape. Variability, in contrast, is not consistently affected by temperature. Finally, we investigated the specific relationship between individual variation and fluctuating asymmetry. Using metric multi-dimensional scaling we show that the related patterns of wing shape variation are not identical, supporting the view that the underlying developmental processes are to a certain extent different.

  15. Rational engineering of enzyme allosteric regulation through sequence evolution analysis.

    Directory of Open Access Journals (Sweden)

    Jae-Seong Yang

    Full Text Available Control of enzyme allosteric regulation is required to drive metabolic flux toward desired levels. Although the three-dimensional (3D structures of many enzyme-ligand complexes are available, it is still difficult to rationally engineer an allosterically regulatable enzyme without decreasing its catalytic activity. Here, we describe an effective strategy to deregulate the allosteric inhibition of enzymes based on the molecular evolution and physicochemical characteristics of allosteric ligand-binding sites. We found that allosteric sites are evolutionarily variable and comprised of more hydrophobic residues than catalytic sites. We applied our findings to design mutations in selected target residues that deregulate the allosteric activity of fructose-1,6-bisphosphatase (FBPase. Specifically, charged amino acids at less conserved positions were substituted with hydrophobic or neutral amino acids with similar sizes. The engineered proteins successfully diminished the allosteric inhibition of E. coli FBPase without affecting its catalytic efficiency. We expect that our method will aid the rational design of enzyme allosteric regulation strategies and facilitate the control of metabolic flux.

  16. Structural Evolution in Photoactive Yellow Protein Studied by Femtosecond Stimulated Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yoshizawa M.

    2013-03-01

    Full Text Available Ultrafast structural evolution in photoactive yellow protein (PYP is studied by femtosecond stimulated Raman spectroscopy. A comparison between wild-type PYP and E46Q mutant reveals that the hydrogen-bonding network surrounding the chromophore of PYP is immediately rearranged in the electronic excited state.

  17. Star counts as an indicator of galactic structure and quasar evolution

    Science.gov (United States)

    Bahcall, J. N.; Soneira, R. M.

    1980-01-01

    A detailed model of the stellar content of the Galaxy is described briefly. Illustrative applications of the model are made, using existing data, to indicate how star counts can be used to determine some parameters of galactic structure, to detect a massive (stellar) halo, and to constrain models of quasar evolution.

  18. Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO3

    Science.gov (United States)

    Dixon, Charlotte A. L.; Kavanagh, Christopher M.; Knight, Kevin S.; Kockelmann, Winfried; Morrison, Finlay D.; Lightfoot, Philip

    2015-10-01

    The thermal evolution of the crystal structure of the prototypical orthorhombic perovskite LaFeO3 has been studied in detail by powder neutron diffraction in the temperature range 25distortion, which is used to rationalize the unique occurrence of a temperature dependent crossover of the a and c unit cell metrics in this compound.

  19. From fast to slow processes in the evolution of urban and regional settlement structures

    Directory of Open Access Journals (Sweden)

    Wolfgang Weidlich

    1999-01-01

    Full Text Available Complex systems consist of many intertwined organizational levels starting from micro-structures and ending with macrostructures. Their evolution takes place on different time scales: Micropatterns exhibit a fast dynamics whereas macropatterns develop slowly. Urban and regional science can make use of this fact by constructing a hierarchy of models on different spatio-temporal scales.

  20. Kinematic morphology of large-scale structure: evolution from potential to rotational flow

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin; Szalay, Alex; Aragón-Calvo, Miguel A.; Neyrinck, Mark C.; Eyink, Gregory L. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2014-09-20

    As an alternative way to describe the cosmological velocity field, we discuss the evolution of rotational invariants constructed from the velocity gradient tensor. Compared with the traditional divergence-vorticity decomposition, these invariants, defined as coefficients of the characteristic equation of the velocity gradient tensor, enable a complete classification of all possible flow patterns in the dark-matter comoving frame, including both potential and vortical flows. We show that this tool, first introduced in turbulence two decades ago, is very useful for understanding the evolution of the cosmic web structure, and in classifying its morphology. Before shell crossing, different categories of potential flow are highly associated with the cosmic web structure because of the coherent evolution of density and velocity. This correspondence is even preserved at some level when vorticity is generated after shell crossing. The evolution from the potential to vortical flow can be traced continuously by these invariants. With the help of this tool, we show that the vorticity is generated in a particular way that is highly correlated with the large-scale structure. This includes a distinct spatial distribution and different types of alignment between the cosmic web and vorticity direction for various vortical flows. Incorporating shell crossing into closed dynamical systems is highly non-trivial, but we propose a possible statistical explanation for some of the phenomena relating to the internal structure of the three-dimensional invariant space.

  1. Design and analysis of heliostat support structure

    Energy Technology Data Exchange (ETDEWEB)

    Zang Chuncheng; Wang Zhifeng [Inst. of Electrical Engineering, CAS, BJ (China); Liu Xiaobing; Zhang Xiliang [Himin Solar Energy Group Co. Ltd, Dezhou, SD (China); Wang Yanzhong [Beijing Univ. of Aeronautics and Astronautics, BJ (China)

    2008-07-01

    The design method of the heliostat support structure with the aim of reducing the cost maximally is described in this paper. In order to guarantee the strength, stiffness and stability of the structure, dynamic performance and static performance including internal stress and distortion are analyzed by means of VSAP (Visual Structural Analysis Program) finite element computational software. Then the support structure is optimized on the basis of the analysis. (orig.)

  2. Tracing specific synonymous codon-secondary structure correlations through evolution.

    Science.gov (United States)

    Oresic, Matej; Dehn, Michael; Korenblum, Daniel; Shalloway, David

    2003-04-01

    We previously showed that GAU codons are preferred (relative to synonymous GAC codons) for encoding aspartates specifically at the N-termini of alpha-helices in human, but not in E. coli, proteins. To test if this difference reflected a general difference between eucaryotes and procaryotes, we now extended the analysis to include the proteins and coding sequences of mammals, vertebrates, S. cerevisiae, and plants. We found that the GAU-alpha-helix correlation is also strong in non-human mammalian and vertebrate proteins but is much weaker or insignificant in S. cerevisiae and plants. The vertebrate correlations are of sufficient strength to enhance alpha-helix N-terminus prediction. Additional results, including the observation that the correlation is significantly enhanced when proteins that are known to be correctly expressed in recombinant procaryotic systems are excluded, suggest that the correlation is induced at the level of protein translation and folding and not at the nucleic acid level. To the best of our knowledge, it is not explicable by the canonical picture of protein expression and folding, suggesting the existence of a novel evolutionary selection mechanism. One possible explanation is that some alpha-helix N-terminal GAU codons may facilitate correct co-translational folding in vertebrates.

  3. Gene structure and evolution of transthyretin in the order Chiroptera.

    Science.gov (United States)

    Khwanmunee, Jiraporn; Leelawatwattana, Ladda; Prapunpoj, Porntip

    2016-02-01

    Bats are mammals in the order Chiroptera. Although many extensive morphologic and molecular genetics analyses have been attempted, phylogenetic relationships of bats has not been completely resolved. The paraphyly of microbats is of particular controversy that needs to be confirmed. In this study, we attempted to use the nucleotide sequence of transthyretin (TTR) intron 1 to resolve the relationship among bats. To explore its utility, the complete sequences of TTR gene and intron 1 region of bats in Vespertilionidae: genus Eptesicus (Eptesicus fuscus) and genus Myotis (Myotis brandtii, Myotis davidii, and Myotis lucifugus), and Pteropodidae (Pteropus alecto and Pteropus vampyrus) were extracted from the retrieved sequences, whereas those of Rhinoluphus affinis and Scotophilus kuhlii were amplified and sequenced. The derived overall amino sequences of bat TTRs were found to be very similar to those in other eutherians but differed from those in other classes of vertebrates. However, missing of amino acids from N-terminal or C-terminal region was observed. The phylogenetic analysis of amino acid sequences suggested bat and other eutherian TTRs lineal descent from a single most recent common ancestor which differed from those of non-placental mammals and the other classes of vertebrates. The splicing of bat TTR precursor mRNAs was similar to those of other eutherian but different from those of marsupial, bird, reptile and amphibian. Based on TTR intron 1 sequence, the inferred evolutionary relationship within Chiroptera revealed more closely relatedness of R. affinis to megabats than to microbats. Accordingly, the paraphyly of microbats was suggested.

  4. An Analysis on a Negotiation Model Based on Multiagent Systems with Symbiotic Learning and Evolution

    Science.gov (United States)

    Hossain, Md. Tofazzal

    This study explores an evolutionary analysis on a negotiation model based on Masbiole (Multiagent Systems with Symbiotic Learning and Evolution) which has been proposed as a new methodology of Multiagent Systems (MAS) based on symbiosis in the ecosystem. In Masbiole, agents evolve in consideration of not only their own benefits and losses, but also the benefits and losses of opponent agents. To aid effective application of Masbiole, we develop a competitive negotiation model where rigorous and advanced intelligent decision-making mechanisms are required for agents to achieve solutions. A Negotiation Protocol is devised aiming at developing a set of rules for agents' behavior during evolution. Simulations use a newly developed evolutionary computing technique, called Genetic Network Programming (GNP) which has the directed graph-type gene structure that can develop and design the required intelligent mechanisms for agents. In a typical scenario, competitive negotiation solutions are reached by concessions that are usually predetermined in the conventional MAS. In this model, however, not only concession is determined automatically by symbiotic evolution (making the system intelligent, automated, and efficient) but the solution also achieves Pareto optimal automatically.

  5. Structural similarity of loops in protein families: toward the understanding of protein evolution

    OpenAIRE

    Madej Thomas; Panchenko Anna R

    2005-01-01

    Abstract Background Protein evolution and protein classification are usually inferred by comparing protein cores in their conserved aligned parts. Structurally aligned protein regions are separated by less conserved loop regions, where sequence and structure locally deviate from each other and do not superimpose well. Results Our results indicate that even longer protein loops can not be viewed as "random coils" and for the majority of protein families in our test set there exists a linear co...

  6. Fluorous ‘ponytails’ lead to strong gelators showing thermally induced structure evolution.

    OpenAIRE

    Kumari, Harshita; Armitage, Sarah E.; Kline, Steven R.; Damodaran, Krishna K.; Kennedy, Stuart R.; Atwood, Jerry L.; Steed, Jonathan W

    2015-01-01

    Appending perfluoroalkyl substituents to bis(urea) gelators results in significantly decreased inter-chain interactions with markedly thinner fibres and hence more cross-linked and more transparent gels with potential applications in the crystallisation of fluorinated pharmaceuticals. Gel structure has been probed by detailed SANS measurements which indicate a surprising structure evolution on thermal cycling, not seen for hydrocarbon analogues. The SANS data are complemented by the single cr...

  7. Cluster Structure in Cosmological Simulations I: Correlation to Observables, Mass Estimates, and Evolution

    OpenAIRE

    Jeltema, Tesla E.; Hallman, Eric J.; Burns, Jack O.; Motl, Patrick M

    2007-01-01

    We use Enzo, a hybrid Eulerian AMR/N-body code including non-gravitational heating and cooling, to explore the morphology of the X-ray gas in clusters of galaxies and its evolution in current generation cosmological simulations. We employ and compare two observationally motivated structure measures: power ratios and centroid shift. Overall, the structure of our simulated clusters compares remarkably well to low-redshift observations, although some differences remain that may point to incomple...

  8. Amplitude and phase evolution of optical fields inside periodic photonic structures

    OpenAIRE

    Flück, E.; Hammer, M; Otter, A.M.; Korterik, J P; Kuipers, L.; Hulst, van der, R.W.M.

    2003-01-01

    Optical amplitude distributions of light inside periodic photonic structures are visualized with subwavelength resolution. In addition, using a phase-sensitive photon scanning tunneling microscope, we simultaneously map the phase evolution of light. Two different structures, which consist of a ridge wave-guide containing periodic arrays of nanometer scale features, are investigated. We determine the wavelength dependence of the exponential decay rate inside the periodic arrays. Furthermore, v...

  9. Magnetic structure evolution in mechanically milled nanostructured ZnFe2O4 particles

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Wynn, P.; Mørup, Steen;

    1999-01-01

    Nanostructured partially-inverted ZnFe2O4 particles have been prepared from bulk ZnFe2O4 by high-energy ball milling in an open container. The grain size reduction, cation site distributions, and the evolution of magnetic structures have been studied by x-ray diffraction with Rietveld structure...... refinements, transmission electron microscopy, and Mossbauer spectroscopy. It is found that a change of magnetic structure from an antiferromagnetic to a ferrimagnetic (or ferromagnetic) structure occurs in the milled samples. This change is correlated with the redistribution of the cations, Zn and Fe...

  10. High Resolution Structure of Deinococcus Bacteriophytochrome Yields New Insights into Phytochrome Architecture and Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Jeremiah R.; Zhang, Junrui; Brunzelle, Joseph S.; Vierstra, Richard D.; Forest, Katrina T. (NWU); (UW)

    2010-03-08

    Phytochromes are red/far red light photochromic photoreceptors that direct many photosensory behaviors in the bacterial, fungal, and plant kingdoms. They consist of an N-terminal domain that covalently binds a bilin chromophore and a C-terminal region that transmits the light signal, often through a histidine kinase relay. Using x-ray crystallography, we recently solved the first three-dimensional structure of a phytochrome, using the chromophore-binding domain of Deinococcus radiodurans bacterial phytochrome assembled with its chromophore, biliverdin IX{alpha}. Now, by engineering the crystallization interface, we have achieved a significantly higher resolution model. This 1.45 {angstrom} resolution structure helps identify an extensive buried surface between crystal symmetry mates that may promote dimerization in vivo. It also reveals that upon ligation of the C3{sup 2} carbon of biliverdin to Cys{sup 24}, the chromophore A-ring assumes a chiral center at C2, thus becoming 2(R),3(E)-phytochromobilin, a chemistry more similar to that proposed for the attached chromophores of cyanobacterial and plant phytochromes than previously appreciated. The evolution of bacterial phytochromes to those found in cyanobacteria and higher plants must have involved greater fitness using more reduced bilins, such as phycocyanobilin, combined with a switch of the attachment site from a cysteine near the N terminus to one conserved within the cGMP phosphodiesterase/adenyl cyclase/FhlA domain. From analysis of site-directed mutants in the D. radiodurans phytochrome, we show that this bilin preference was partially driven by the change in binding site, which ultimately may have helped photosynthetic organisms optimize shade detection. Collectively, these three-dimensional structural results better clarify bilin/protein interactions and help explain how higher plant phytochromes evolved from prokaryotic progenitors.

  11. COMPARATIVE ANALYSIS OF THE RECENT EVOLUTIONS OF ROMANIAN AND EUROPEAN UNION'S COMPETITIVENESS

    Directory of Open Access Journals (Sweden)

    Felea Adrian Ioan

    2011-07-01

    Full Text Available The main subject of this paper refers to an analysis of the recent trends and evolution of Romanian competitiveness compared to the European Union competitiveness and it is structured in four main parts. The first section of the paper regards an introduction of the competitiveness evolution process, recalling the three actual evaluation models of the competitiveness level. In the second part of the paper there can be found the competitiveness indexes practiced and published by the World Economic Forum, indicators that are structured on three main levels as following: the Global Competitiveness Index and its aggregate indicators that are developed on three categories of factors that are essential for the competitiveness process (Basic requirements, Efficienty Enhancers, Innovation and sophistication factors and the indexes associated to the twelve pillars of competitiveness: Institutions, Infrastructure, Macroeconomic stability, Health and primary education, Higer education and training, Goods market efficiency, Labor market efficiency, Financial market sophistication Technological readiness, Market size, Business sophistication, Innovation. Based on the values obtained after consulting the World Economic Forum Reports and regarding the competitiveness from a global perspective, the third part of the paper presents a comparative analyisis of the evolution of the Romanian competitiveness process and the one of the EU25. In the last part of the paper there can be found the conclusions of this analysis, with respect to the values found This paper is part of the doctoral thesis entitled "Increased Competitiveness in the Romanian economy, in the context of Sustainable Development, coordinated by Professor Michael Berinde University of Oradea, Faculty of Economics. Doctoral research is supported by Human Resources Development Operational Programme 2007-2013, Contract POSDRU/CPP107/DMI1.5/S/80272 , "Doctoral programs to train researchers performing

  12. Gene structure and evolution of transthyretin in the order Chiroptera.

    Science.gov (United States)

    Khwanmunee, Jiraporn; Leelawatwattana, Ladda; Prapunpoj, Porntip

    2016-02-01

    Bats are mammals in the order Chiroptera. Although many extensive morphologic and molecular genetics analyses have been attempted, phylogenetic relationships of bats has not been completely resolved. The paraphyly of microbats is of particular controversy that needs to be confirmed. In this study, we attempted to use the nucleotide sequence of transthyretin (TTR) intron 1 to resolve the relationship among bats. To explore its utility, the complete sequences of TTR gene and intron 1 region of bats in Vespertilionidae: genus Eptesicus (Eptesicus fuscus) and genus Myotis (Myotis brandtii, Myotis davidii, and Myotis lucifugus), and Pteropodidae (Pteropus alecto and Pteropus vampyrus) were extracted from the retrieved sequences, whereas those of Rhinoluphus affinis and Scotophilus kuhlii were amplified and sequenced. The derived overall amino sequences of bat TTRs were found to be very similar to those in other eutherians but differed from those in other classes of vertebrates. However, missing of amino acids from N-terminal or C-terminal region was observed. The phylogenetic analysis of amino acid sequences suggested bat and other eutherian TTRs lineal descent from a single most recent common ancestor which differed from those of non-placental mammals and the other classes of vertebrates. The splicing of bat TTR precursor mRNAs was similar to those of other eutherian but different from those of marsupial, bird, reptile and amphibian. Based on TTR intron 1 sequence, the inferred evolutionary relationship within Chiroptera revealed more closely relatedness of R. affinis to megabats than to microbats. Accordingly, the paraphyly of microbats was suggested. PMID:26681450

  13. Estimating the number of clusters via system evolution for cluster analysis of gene expression data.

    Science.gov (United States)

    Wang, Kaijun; Zheng, Jie; Zhang, Junying; Dong, Jiyang

    2009-09-01

    The estimation of the number of clusters (NC) is one of crucial problems in the cluster analysis of gene expression data. Most approaches available give their answers without the intuitive information about separable degrees between clusters. However, this information is useful for understanding cluster structures. To provide this information, we propose system evolution (SE) method to estimate NC based on partitioning around medoids (PAM) clustering algorithm. SE analyzes cluster structures of a dataset from the viewpoint of a pseudothermodynamics system. The system will go to its stable equilibrium state, at which the optimal NC is found, via its partitioning process and merging process. The experimental results on simulated and real gene expression data demonstrate that the SE works well on the data with well-separated clusters and the one with slightly overlapping clusters. PMID:19527960

  14. Genome-Wide Analysis of Human Metapneumovirus Evolution

    Science.gov (United States)

    Kim, Jin Il; Park, Sehee; Lee, Ilseob; Park, Kwang Sook; Kwak, Eun Jung; Moon, Kwang Mee; Lee, Chang Kyu; Bae, Joon-Yong; Park, Man-Seong; Song, Ki-Joon

    2016-01-01

    Human metapneumovirus (HMPV) has been described as an important etiologic agent of upper and lower respiratory tract infections, especially in young children and the elderly. Most of school-aged children might be introduced to HMPVs, and exacerbation with other viral or bacterial super-infection is common. However, our understanding of the molecular evolution of HMPVs remains limited. To address the comprehensive evolutionary dynamics of HMPVs, we report a genome-wide analysis of the eight genes (N, P, M, F, M2, SH, G, and L) using 103 complete genome sequences. Phylogenetic reconstruction revealed that the eight genes from one HMPV strain grouped into the same genetic group among the five distinct lineages (A1, A2a, A2b, B1, and B2). A few exceptions of phylogenetic incongruence might suggest past recombination events, and we detected possible recombination breakpoints in the F, SH, and G coding regions. The five genetic lineages of HMPVs shared quite remote common ancestors ranging more than 220 to 470 years of age with the most recent origins for the A2b sublineage. Purifying selection was common, but most protein genes except the F and M2-2 coding regions also appeared to experience episodic diversifying selection. Taken together, these suggest that the five lineages of HMPVs maintain their individual evolutionary dynamics and that recombination and selection forces might work on shaping the genetic diversity of HMPVs. PMID:27046055

  15. A Critical Analysis of Chromotherapy and Its Scientific Evolution

    Directory of Open Access Journals (Sweden)

    Samina T. Yousuf Azeemi

    2005-01-01

    Full Text Available Chromotherapy is a method of treatment that uses the visible spectrum (colors of electromagnetic radiation to cure diseases. It is a centuries-old concept used successfully over the years to cure various diseases. We have undertaken a critical analysis of chromotherapy and documented its scientific evolution to date. A few researchers have tried to discover the underlying scientific principles, but without quantitative study. Sufficient published material can be found about the subject that provides a complete system of treatment focused on the treatment methodologies and healing characteristics of colors. A number of studies have elaborated the relationship between the human body and colors. We also show the possibility of carrying out diverse research into chromotherapy that is pertinent to deciphering the quantum mechanical dipole moment of water molecules. The quantum mechanical dipole moment as a result of the absorption of different colors, we conjecture, produces charge quantization phenomena. This review illustrates that the development of science in the field of electromagnetic radiation/energy can be very helpful in discovering new dimensions of this old theory.

  16. Dislocation structure evolution and its effects on cyclic deformation response of AISI 316L stainless steel

    International Nuclear Information System (INIS)

    Research highlights: → The cyclic deformation response of AISI 316L steel is investigated at 20 deg. C. → The corresponding microstructure evolution is characterised by electron microscopy. → A 3D representation of dislocation evolution is proposed based on the observation. → The 3D representation gives a good explanation of the microstructure complexity. → The cyclic deformation response is discussed based on the microstructure evolution. - Abstract: The cyclic deformation response of an austenitic stainless steel is characterised in terms of its cyclic peak tensile stress properties by three stages of behaviour: a hardening stage followed by a softening stage, and finally a stable stress response stage. A series of tests have been performed and interrupted at selected numbers of cycles in the different stages of mechanical response. At each interruption point, specimens have been examined by transmission electron microscopy (TEM) with different beam directions by means of the tilting function in order to investigate the formation and the development of dislocation structures from the as-received condition until the end of fatigue life. A new 3D representation of dislocation structure evolution during cyclic loading is proposed on the basis of the microstructural observations. The 3D representation provides a deeper insight into the development of dislocation structures in AISI 316L during low cycle fatigue loading at room temperature. By investigating the dislocation evolution, the study shows that the hardening response is mainly associated with an increase of total dislocation density, whereas the softening stage is a result of the formation of dislocation-free regions. Further development of the dislocation structure into a cellular structure is responsible for the stable stress response stage.

  17. Collapse Analysis of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2008-01-01

    to behave robust according to the sued probabilistic approach. However, the present probabilistic approach for robustness evaluation has to be further developed for a general application to timber systems, and a simplified approach suitable for day-to-day engineering purposes must be identified....... of Structures and a probabilistic modelling of the timber material proposed in the Probabilistic Model Code (PMC) of the Joint Committee on Structural Safety (JCSS). Due to the framework in the Danish Code the timber structure has to be evaluated with respect to the following criteria where at least one shall...... to criteria a) and b) the timber frame structure has one column with a reliability index a bit lower than an assumed target level. By removal three columns one by one no significant extensive failure of the entire structure or significant parts of it are obtained. Therefore the structure can be considered...

  18. Structured Sparse Principal Component Analysis

    OpenAIRE

    R. Jenatton; G. Obozinski; Bach, F.

    2009-01-01

    We present an extension of sparse PCA, or sparse dictionary learning, where the sparsity patterns of all dictionary elements are structured and constrained to belong to a prespecified set of shapes. This \\emph{structured sparse PCA} is based on a structured regularization recently introduced by [1]. While classical sparse priors only deal with \\textit{cardinality}, the regularization we use encodes higher-order information about the data. We propose an efficient and simple optimization proced...

  19. Truncated Moment Analysis of Nucleon Structure Functions

    Energy Technology Data Exchange (ETDEWEB)

    A. Psaker; W. Melnitchouk; M. E. Christy; C. E. Keppel

    2007-11-16

    We employ a novel new approach using "truncated" moments, or integrals of structure functions over restricted regions of x, to study local quark-hadron duality, and the degree to which individual resonance regions are dominated by leading twists. Because truncated moments obey the same Q^2 evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.

  20. The IQD gene family in soybean: structure, phylogeny, evolution and expression.

    Directory of Open Access Journals (Sweden)

    Lin Feng

    Full Text Available Members of the plant-specific IQ67-domain (IQD protein family are involved in plant development and the basal defense response. Although systematic characterization of this family has been carried out in Arabidopsis, tomato (Solanum lycopersicum, Brachypodium distachyon and rice (Oryza sativa, systematic analysis and expression profiling of this gene family in soybean (Glycine max have not previously been reported. In this study, we identified and structurally characterized IQD genes in the soybean genome. A complete set of 67 soybean IQD genes (GmIQD1-67 was identified using Blast search tools, and the genes were clustered into four subfamilies (IQD I-IV based on phylogeny. These soybean IQD genes are distributed unevenly across all 20 chromosomes, with 30 segmental duplication events, suggesting that segmental duplication has played a major role in the expansion of the soybean IQD gene family. Analysis of the Ka/Ks ratios showed that the duplicated genes of the GmIQD family primarily underwent purifying selection. Microsynteny was detected in most pairs: genes in clade 1-3 might be present in genome regions that were inverted, expanded or contracted after the divergence; most gene pairs in clade 4 showed high conservation with little rearrangement among these gene-residing regions. Of the soybean IQD genes examined, six were most highly expressed in young leaves, six in flowers, one in roots and two in nodules. Our qRT-PCR analysis of 24 soybean IQD III genes confirmed that these genes are regulated by MeJA stress. Our findings present a comprehensive overview of the soybean IQD gene family and provide insights into the evolution of this family. In addition, this work lays a solid foundation for further experiments aimed at determining the biological functions of soybean IQD genes in growth and development.

  1. Helium-Related Defect Evolution in Titanium Films by Slow Positron Beam Analysis

    International Nuclear Information System (INIS)

    Various helium-containing titanium films were deposited on Si substrates by magnetron sputtering under different helium/argon (He/Ar) ambiances. Helium concentrations and corresponding depth profiles in the Ti films are obtained by elastic recoil detection analysis (ERDA). X-ray diffraction (XRD) measurements are carried out to evaluate the crystallization of the titanium films. Vacancy-type defects and their depth profiles were revealed by slow positron beam analysis (SPBA). It is found that the defect-characteristic parameter S rises with the increment of the He/Ar flow ratios. The variation of S indicates the formation and evolution of various He-related defects, with uniform distribution into the depth around 400 nm. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Analysis of piezoelectric structures and devices

    CERN Document Server

    Chen, Weiqiu; Wang, Ji

    2013-01-01

    This edited work covers piezoelectric materials in the form of beams, plates, shells, and other structural components in modern devices and structures. Applications are frequency control and detection functions in resonators, sensors, actuators, oscillations, and other smart and intelligent structures. The contributions cover novel methods for the analysis of piezoelectric structures including wave propagation, high frequency vibration, material characterization, and optimization of structures. Understanding of these methods is increasingly important in the design and modelling of next generat

  3. Time evolution of electron structure in femtosecond heated warm dense molybdenum.

    Science.gov (United States)

    Recoules, V.; Dorchies, F.; Bouchet, J.; Fourment, C.; Leguay, P. M.; Cho, B. I.; Engelhorn, K.; Nakatsutsumi, M.; Ozkan, C.; Tshentscher, T.; Harmand, M.; Toleikis, S.; Stormer, M.; Galtier, E.; Lee, H. J.; Nagler, B.; Heimann, P. A.; Gaudin, J.

    2015-11-01

    The time evolution of the electron structure is investigated in a molybdenum foil heated up to the warm dense matter regime by a femtosecond laser pulse, through time-resolved XANES spectroscopy. Spectra are measured with independent control of temperature and density. They are successfully compared with ab initio quantum molecular dynamic calculations and an analytical model. We demonstrate that the observed white line in the L3-edge reveals the time evolution of the electron density of state from the solid to the hot (a few eV) and expanding liquid.

  4. Conservation of mRNA secondary structures may filter out mutations in Escherichia coli evolution.

    Science.gov (United States)

    Chursov, Andrey; Frishman, Dmitrij; Shneider, Alexander

    2013-09-01

    Recent reports indicate that mutations in viral genomes tend to preserve RNA secondary structure, and those mutations that disrupt secondary structural elements may reduce gene expression levels, thereby serving as a functional knockout. In this article, we explore the conservation of secondary structures of mRNA coding regions, a previously unknown factor in bacterial evolution, by comparing the structural consequences of mutations in essential and nonessential Escherichia coli genes accumulated over 40 000 generations in the course of the 'long-term evolution experiment'. We monitored the extent to which mutations influence minimum free energy (MFE) values, assuming that a substantial change in MFE is indicative of structural perturbation. Our principal finding is that purifying selection tends to eliminate those mutations in essential genes that lead to greater changes of MFE values and, therefore, may be more disruptive for the corresponding mRNA secondary structures. This effect implies that synonymous mutations disrupting mRNA secondary structures may directly affect the fitness of the organism. These results demonstrate that the need to maintain intact mRNA structures imposes additional evolutionary constraints on bacterial genomes, which go beyond preservation of structure and function of the encoded proteins.

  5. Bayesian large-scale structure inference and cosmic web analysis

    CERN Document Server

    Leclercq, Florent

    2015-01-01

    Surveys of the cosmic large-scale structure carry opportunities for building and testing cosmological theories about the origin and evolution of the Universe. This endeavor requires appropriate data assimilation tools, for establishing the contact between survey catalogs and models of structure formation. In this thesis, we present an innovative statistical approach for the ab initio simultaneous analysis of the formation history and morphology of the cosmic web: the BORG algorithm infers the primordial density fluctuations and produces physical reconstructions of the dark matter distribution that underlies observed galaxies, by assimilating the survey data into a cosmological structure formation model. The method, based on Bayesian probability theory, provides accurate means of uncertainty quantification. We demonstrate the application of BORG to the Sloan Digital Sky Survey data and describe the primordial and late-time large-scale structure in the observed volume. We show how the approach has led to the fi...

  6. ANALYSIS OF THE EVOLUTION ON THE LAYOUT AND STRUCTURE OF REGIONAL FOOD PRODUCTION IN CHINA%中国粮食生产布局与结构区域演变分析

    Institute of Scientific and Technical Information of China (English)

    屈宝香; 张华; 李刚

    2011-01-01

    This paper analyzed the trend in optimizing the regional layout and the structure characteristics of food production in China, and provided some countermeasures to optimize the structure and layout of regional food production, such as adjustment of crops structure need to stabilize food development, adjustment of food structure need to think about both the species and regional balance, the layout of food production need to support logistics processing industry, and the layout of food industry need to conserve land and water resources et al.%该文分析了我国粮食生产区域布局优化趋势与粮食生产区域结构演变的特点,提出了农作物结构调整需要保证稳定粮食发展、粮食结构调整需要兼顾品种和区域平衡、粮食生产布局需要物流加工产业配套及粮食产业布局要注意水土资源的节约等粮食布局与结构优化相应的对策建议.

  7. Robustness Analysis of Kinetic Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    Kinetic structures in architecture follows a new trend which is emerging in responsive architecture coined by Nicholas Negroponte when he proposed that architecture may benefit from the integration of computing power into built spaces and structures, and that better performing, more rational buil...

  8. Complete Chloroplast Genome of the Wollemi Pine (Wollemia nobilis: Structure and Evolution.

    Directory of Open Access Journals (Sweden)

    Jia-Yee S Yap

    Full Text Available The Wollemi pine (Wollemia nobilis is a rare Southern conifer with striking morphological similarity to fossil pines. A small population of W. nobilis was discovered in 1994 in a remote canyon system in the Wollemi National Park (near Sydney, Australia. This population contains fewer than 100 individuals and is critically endangered. Previous genetic studies of the Wollemi pine have investigated its evolutionary relationship with other pines in the family Araucariaceae, and have suggested that the Wollemi pine genome contains little or no variation. However, these studies were performed prior to the widespread use of genome sequencing, and their conclusions were based on a limited fraction of the Wollemi pine genome. In this study, we address this problem by determining the entire sequence of the W. nobilis chloroplast genome. A detailed analysis of the structure of the genome is presented, and the evolution of the genome is inferred by comparison with the chloroplast sequences of other members of the Araucariaceae and the related family Podocarpaceae. Pairwise alignments of whole genome sequences, and the presence of unique pseudogenes, gene duplications and insertions in W. nobilis and Araucariaceae, indicate that the W. nobilis chloroplast genome is most similar to that of its sister taxon Agathis. However, the W. nobilis genome contains an unusually high number of repetitive sequences, and these could be used in future studies to investigate and conserve any remnant genetic diversity in the Wollemi pine.

  9. Mathematical and computational analyses of cracking formation fracture morphology and its evolution in engineering materials and structures

    CERN Document Server

    Sumi, Yoichi

    2014-01-01

    This book is about the pattern formation and the evolution of crack propagation in engineering materials and structures, bridging mathematical analyses of cracks based on singular integral equations, to computational simulation of engineering design. The first two parts of this book focus on elasticity and fracture and provide the basis for discussions on fracture morphology and its numerical simulation, which may lead to a simulation-based fracture control in engineering structures. Several design concepts are discussed for the prevention of fatigue and fracture in engineering structures, including safe-life design, fail-safe design, damage tolerant design. After starting with basic elasticity and fracture theories in parts one and two, this book focuses on the fracture morphology that develops due to the propagation of brittle cracks or fatigue cracks.   In part three, the mathematical analysis of a curved crack is precisely described, based on the perturbation method. The stability theory of interactive ...

  10. Quantitative tracking of grain structure evolution in a nanocrystalline metal during cyclic loading

    International Nuclear Information System (INIS)

    Molecular dynamics simulations were used to quantify mechanically induced structural evolution in nanocrystalline Al with an average grain size of 5 nm. A polycrystalline sample was cyclically strained at different temperatures, while a recently developed grain tracking algorithm was used to measure the relative contributions of novel deformation mechanisms such as grain rotation and grain sliding. Sample texture and grain size were also tracked during cycling, to show how nanocrystalline plasticity rearranges overall grain structure and alters the grain boundary network. While no obvious texture is developing during cycling, the processes responsible for plasticity act collectively to alter the interfacial network. Cyclic loading led to the formation of many twin boundaries throughout the sample as well as the occasional coalescence of neighboring grains, with higher temperatures causing more evolution. A temperature-dependent cyclic strengthening effect was observed, demonstrating that both the structure and properties of nanocrystalline metals can be dynamic during loading. (paper)

  11. The unusual morphology, structure, and magnetic property evolution of glassy carbon upon high pressure treatment

    Energy Technology Data Exchange (ETDEWEB)

    Jin, C.Q.; Wang, X.; Liu, Z.X.; Zhang, Y.L.; Li, F.Y.; Yu, R.C. [Chinese Academy of Sciences, Beijing (China). Inst. of Physics. Beijing High Pressure Research Center

    2003-12-01

    Glassy carbon (GC) has been high-pressure high-temperature treated. An interesting morphology evolution from the pristine sample to the high pressure products was observed. It is found that GC can be graphitized under pressure at a temperature much lower than that at ambient condition. Furthermore the in-situ structure and electrical measurements of GC and graphitized glassy carbon (GGC) under high temperature and high pressure have been investigated up to 30 GPa. We particularly emphasize the unusual magnetic properties of GC treated under high pressures and high temperatures. A paramagnetic to ferromagnetic-like, and then to superconducting (a diamagnetic signal with hysteresis magnetic response) -like behavior, which can be observed at temperatures as high as 80 K, appears as a successive evolution from the initial GC to GGC in accordance with three regions distinguished by the graphitization temperature. This interesting evolution of magnetic properties probably evokes the new understanding of carbon element. (author)

  12. Nonlinear structural analysis using integrated force method

    Indian Academy of Sciences (India)

    N R B Krishnam Raju; J Nagabhushanam

    2000-08-01

    Though the use of the integrated force method for linear investigations is well-recognised, no efforts were made to extend this method to nonlinear structural analysis. This paper presents the attempts to use this method for analysing nonlinear structures. General formulation of nonlinear structural analysis is given. Typically highly nonlinear bench-mark problems are considered. The characteristic matrices of the elements used in these problems are developed and later these structures are analysed. The results of the analysis are compared with the results of the displacement method. It has been demonstrated that the integrated force method is equally viable and efficient as compared to the displacement method.

  13. Neutron diffraction analysis of crystal magnetic structures

    International Nuclear Information System (INIS)

    An investigation of the state-of-the art of the neutron diffraction analysis of magnetic structures from the point of view of the theory of crystal symmetry is given. Various and numerous structures determined from the neutron diffraction analysis investigations can be classified and described with the theory of space group representations of crystals. The analysis of quite a number of various magnetic structures shows that they arise according to Landau hypothesis. The foundations of a symmetry analysis of magnetic structures and the methods for their determination are given. A physical explanation is given for the existence of magnetic structures. The experimental investigations of the crystal lattice distortions accompanying a magnetic ordering are reviewed. In this review is given a symmetry approach to the description of the magnetic structures of crystals; and a possibility to analyze them by a scattering of nonpolarized and polarized neutrons

  14. Formation and evolution of tweed structures on high-purity aluminum polycrystalline foils under cyclic tension

    International Nuclear Information System (INIS)

    Peculiarities of formation and evolution of tweed structures on the surface of high-purity aluminum polycrystalline foils under cyclic tension were studied using an atom force microscope and a white light interferometer. Tweed structures of micron and submicron sizes were found on the foils at different number of cycles. In the range of 42,000 < N < 95,000 cycles destruction of tweed patterns is observed, which leads to their disappearance from the surface of the foils. Formation of tweed structures of various scales is discussed in terms of the Grinfeld instability

  15. Formation and evolution of tweed structures on high-purity aluminum polycrystalline foils under cyclic tension

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, P. V., E-mail: kpv@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Vlasov, I. V. [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Sklyarova, E. A.; Smekalina, T. V. [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    Peculiarities of formation and evolution of tweed structures on the surface of high-purity aluminum polycrystalline foils under cyclic tension were studied using an atom force microscope and a white light interferometer. Tweed structures of micron and submicron sizes were found on the foils at different number of cycles. In the range of 42,000 < N < 95,000 cycles destruction of tweed patterns is observed, which leads to their disappearance from the surface of the foils. Formation of tweed structures of various scales is discussed in terms of the Grinfeld instability.

  16. Formation and evolution of tweed structures on high-purity aluminum polycrystalline foils under cyclic tension

    Science.gov (United States)

    Kuznetsov, P. V.; Vlasov, I. V.; Sklyarova, E. A.; Smekalina, T. V.

    2015-10-01

    Peculiarities of formation and evolution of tweed structures on the surface of high-purity aluminum polycrystalline foils under cyclic tension were studied using an atom force microscope and a white light interferometer. Tweed structures of micron and submicron sizes were found on the foils at different number of cycles. In the range of 42,000 < N < 95,000 cycles destruction of tweed patterns is observed, which leads to their disappearance from the surface of the foils. Formation of tweed structures of various scales is discussed in terms of the Grinfeld instability.

  17. Hydrophobic Core Variations Provide a Structural Framework for Tyrosine Kinase Evolution and Functional Specialization.

    Science.gov (United States)

    Mohanty, Smita; Oruganty, Krishnadev; Kwon, Annie; Byrne, Dominic P; Ferries, Samantha; Ruan, Zheng; Hanold, Laura E; Katiyar, Samiksha; Kennedy, Eileen J; Eyers, Patrick A; Kannan, Natarajan

    2016-02-01

    Protein tyrosine kinases (PTKs) are a group of closely related enzymes that have evolutionarily diverged from serine/threonine kinases (STKs) to regulate pathways associated with multi-cellularity. Evolutionary divergence of PTKs from STKs has occurred through accumulation of mutations in the active site as well as in the commonly conserved hydrophobic core. While the functional significance of active site variations is well understood, relatively little is known about how hydrophobic core variations contribute to PTK evolutionary divergence. Here, using a combination of statistical sequence comparisons, molecular dynamics simulations, mutational analysis and in vitro thermostability and kinase assays, we investigate the structural and functional significance of key PTK-specific variations in the kinase core. We find that the nature of residues and interactions in the hydrophobic core of PTKs is strikingly different from other protein kinases, and PTK-specific variations in the core contribute to functional divergence by altering the stability and dynamics of the kinase domain. In particular, a functionally critical STK-conserved histidine that stabilizes the regulatory spine in STKs is selectively mutated to an alanine, serine or glutamate in PTKs, and this loss-of-function mutation is accommodated, in part, through compensatory PTK-specific interactions in the core. In particular, a PTK-conserved phenylalanine in the I-helix appears to structurally and functionally compensate for the loss of STK-histidine by interacting with the regulatory spine, which has far-reaching effects on enzyme activity, inhibitor sensing, and stability. We propose that hydrophobic core variations provide a selective advantage during PTK evolution by increasing the conformational flexibility, and therefore the allosteric potential of the kinase domain. Our studies also suggest that Tyrosine Kinase Like kinases such as RAF are intermediates in PTK evolutionary divergence inasmuch as they

  18. THE EVOLUTION OF AGRICULTURAL SECTOR THROUGH FINANCIAL STATEMENTS ANALYSIS

    Directory of Open Access Journals (Sweden)

    Theodore PAPAELIAS

    2012-09-01

    Full Text Available In 1950 Hellas was probably the most agricultural country of the West. Within the first thirty years (1950-80 the economic model that was followed had as a consequence the contraction of the sector. Nevertheless, in 1981, when the country entered European Union, it had still an extended agricultural nature. Even in 2010 (after the enlargement of E.U. to 27 members in 2004 and 2007 the labor force percentage of the farming sector was among the highest rates. Herewith it is intended to present the evolution of the sector though the analysis of the balance sheet variations of Greek agriculture. Based on a former extended literature survey, but also extracting data from Agricultural Bank of Greece (ATE, it was tried to evaluate, not only at the country level, but also at the prefectural one, data of assets and liabilities during the post-war era and per decade. The evidence derived from the fixed assets movements suggests that despite the capital accumulation, and the relatively satisfactory lending in working capital by ATE, the sector is moving near the edge of the cliff. Neither the integration of the country in the E.U. or later in the Economic and Monetary Union in 2000 managed to alter the trends formed in the period 1950-80.The contribution hereof lies in the presentation of the financial statements variations, on the one part, a methodology rather rare in Greek bibliography and relatively uncommon in the international one (data being assessed mainly with macroeconomic tools and on the other part, in the investigation of the consequences of the economic policy applied throughout the post-war period.

  19. Macroeconomic Models used in the Structural Analysis of the Gross Domestic Product

    Directory of Open Access Journals (Sweden)

    Constantin Anghelache

    2013-07-01

    Full Text Available This paper describes a use case for macro economical models, the objective being the structural analysis of the Gross Domestic Product. The authors offer a snapshot on GDP evolution, the econometric models proposed for analysis are designed with the help of EViews software. Its performances are determined through the optics of the statistical tests.

  20. Structural Analysis of the Upper Internal Structure in PGSFR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. H.; Koo, G. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    The upper internal structure (UIS) is a package of hardware suspended from the rotating plug to about 20 cm above the core assemblies. The functions of the UIS are to support shroud tubes containing the primary and secondary control rod drivelines and preserve critical alignments between these drivelines and the core lattice, under normal and off-normal conditions. In addition, the UIS produces sufficient coolant mixing to mitigate thermal transients to downstream components and provides an opening for the In-Vessel transfer machine to access inner core positions without interfacing with the control rod drive lines and the upper core instrumentation package. The radial position of the shroud tube is fixed by three horizontal guide plates and the lower guide plate is close to the core assemblies and is perforated to permit most of the core effluent to reach the region between guide plates. In this study, the primary stress analysis for dead weight was carried out and the thermal stress analysis considering the coolant temperature around the UIS was performed. In addition, the mode characteristics of the structure by the natural frequency analysis were evaluated. The structural analysis model is developed to evaluate the structural integrity of the UIS. The primary stress analysis, the thermal stress analysis and the natural frequency analysis for the UIS are performed, and the maximum stresses and displacements are evaluated. From the analysis results, it is confirmed that the large local stresses don't occur near the holes and through the wall thicknesses of the structure. In addition, the maximum temperature of the UIS is calculated as 545 .deg. C from the thermal analysis and the structure should be evaluated by the ASME design rules at a high temperature. In the future, the more detailed design will be performed by the high temperature evaluation procedure according to the ASME SEC. III, Div.5.

  1. Evolution of the structure of tail feathers: implications for the theory of sexual selection.

    Science.gov (United States)

    Aparicio, José Miguel; Bonal, Raúl; Cordero, Pedro J

    2003-02-01

    Bird tails are extraordinarily variable in length and functionality. In some species, males have evolved exaggeratedly long tails as a result of sexual selection. Changes in tail length should be associated with changes in feather structure. The study of the evolution of feather structure in bird tails could give insight to understand the causes and means of evolution in relation to processes of sexual selection. In theory, three possible means of tail length evolution in relation to structural components might be expected: (1) a positive relationship between the increase in length and size of structural components maintaining the mechanical properties of the feather; (2) no relationship; that is, enlarging feather length without changes in the structural components; and (3) a negative relationship; that is, enlarging feather length by reducing structural components. These hypotheses were tested using phylogenetic analyses to examine changes in both degree of exaggeration in tail length and structural characteristics of tail feathers (rachis width and density of barbs) in 36 species, including those dimorphic and nondimorphic in tail length. The degree of sexual dimorphism in tail length was negatively correlated with both rachis width and density of barbs in males but not in females. Reinforcing this result, we found that dimorphism in tail length was negatively associated with dimorphism in tail feather structure (rachis width and density of barbs). These results support the third hypothesis, in which the evolution of long feathers occurs at the expense of making them simpler and therefore less costly to produce. However, we do not know the effects of enfeeblement on the costs of bearing. If the total costs increased, the enfeeblement of feathers could be explained as a reinforcement of the honesty of the signal. Alternatively, if total costs were reduced, the strategy could be explained by cheating processes. The study of female preferences for fragile tail

  2. A conceptual approach to model co-evolution of urban structures

    CERN Document Server

    Schweitzer, Frank

    2016-01-01

    Urban structures encompass settlements, characterized by the spatial distribution of built-up areas, but also transportation structures, to connect these built-up areas. These two structures are very different in their origin and function, fulfilling complementary needs: (i) to access space, and (ii) to occupy space. Their evolution cannot be understood by looking at the dynamics of urban aggregations and transportation systems separately. Instead, existing built-up areas feed back on the further development of transportation structures, and the availability of the latter feeds back on the future growth of urban aggregations. To model this co-evolution, we propose an agent-based approach that builds on existing agent-based models for the evolution of trail systems and of urban settlements. The key element in these separate approaches is a generalized communication of agents by means of an adaptive landscape. This landscape is only generated by the agents, but once it exists, it feeds back on their further act...

  3. Probabilistic structural analysis by extremum methods

    Science.gov (United States)

    Nafday, Avinash M.

    1990-01-01

    The objective is to demonstrate discrete extremum methods of structural analysis as a tool for structural system reliability evaluation. Specifically, linear and multiobjective linear programming models for analysis of rigid plastic frames under proportional and multiparametric loadings, respectively, are considered. Kinematic and static approaches for analysis form a primal-dual pair in each of these models and have a polyhedral format. Duality relations link extreme points and hyperplanes of these polyhedra and lead naturally to dual methods for system reliability evaluation.

  4. Genomic and protein structural maps of adaptive evolution of human influenza A virus to increased virulence in the mouse.

    Directory of Open Access Journals (Sweden)

    Jihui Ping

    Full Text Available Adaptive evolution is characterized by positive and parallel, or repeated selection of mutations. Mouse adaptation of influenza A virus (IAV produces virulent mutants that demonstrate positive and parallel evolution of mutations in the hemagglutinin (HA receptor and non-structural protein 1 (NS1 interferon antagonist genes. We now present a genomic analysis of all 11 genes of 39 mouse adapted IAV variants from 10 replicate adaptation experiments. Mutations were mapped on the primary and structural maps of each protein and specific mutations were validated with respect to virulence, replication, and RNA polymerase activity. Mouse adapted (MA variants obtained after 12 or 20-21 serial infections acquired on average 5.8 and 7.9 nonsynonymous mutations per genome of 11 genes, respectively. Among a total of 115 nonsynonymous mutations, 51 demonstrated properties of natural selection including 27 parallel mutations. The greatest degree of parallel evolution occurred in the HA receptor and ribonucleocapsid components, polymerase subunits (PB1, PB2, PA and NP. Mutations occurred in host nuclear trafficking factor binding sites as well as sites of virus-virus protein subunit interaction for NP, NS1, HA and NA proteins. Adaptive regions included cap binding and endonuclease domains in the PB2 and PA polymerase subunits. Four mutations in NS1 resulted in loss of binding to the host cleavage and polyadenylation specificity factor (CPSF30 suggesting that a reduction in inhibition of host gene expression was being selected. The most prevalent mutations in PB2 and NP were shown to increase virulence but differed in their ability to enhance replication and demonstrated epistatic effects. Several positively selected RNA polymerase mutations demonstrated increased virulence associated with >300% enhanced polymerase activity. Adaptive mutations that control host range and virulence were identified by their repeated selection to comprise a defined model for

  5. THE ROLE OF THE RELIEF IN THE EVOLUTION, STRUCTURE AND FUNCTIONALITY OF THE ZALĂU URBAN AREA

    Directory of Open Access Journals (Sweden)

    ANDREEA MARIA VÂTCĂ

    2014-11-01

    Full Text Available The role of the relief in the evolution, structure and functionality of the Zalău urban area. The relief represents an important condition for a settlement’s emergence and for its social, economical and territorial evolution. Moreover, it influences the urban structure and the functional organisation of a city. As a result, the configuration of the main built-up area of Zalău has been determined by geomorphological factors which provided, through the hydrographical convergences, a suitable area for territorial expansion. The city’s longitudinal development has unfavourable consequences on the urban functionality. At the same time with the expansion on this direction, the city’s transversal development takes place through the emergence of the Dumbrava Nord neighbourhood. Some dwellings were also built on the slopes, generating stepped apartment blocks and access ways perpendicular to level curves, increasing in this way the value of investments. The extension of the inhabited area, through holiday or permanent houses being built at the foot of the Meseş Mountain and near the Zalău - Aghireş and Zalău-Moigrad roads, confirms the new trend in the urban development of Zalău: The following study analyses the relationships among the relief, the urban built-up area and the territorial development. Thus, the cartographic documentation has included: shooting directory plans from 1939, topographic maps from 1970 and orthophotoplans from 2005, which were used to determine the chronological limits of the built-up area and to analyse their spatial evolution in relationship with the demographic evolution and the favourable characteristics of the relief (<5° declivity and < 250 m altitude. All these are based on geomorphologic mapping and GIS analysis. As a main result, an expansion tendency of the built-up area was identified in relationship with an increase in comfort, which at the same time is being restricted to some extent by geographical

  6. Micro-structural evolution of rubber/clay nanocomposites with vulcanization process

    Directory of Open Access Journals (Sweden)

    2011-09-01

    Full Text Available Brominated isobutyl-isoprene rubber/clay nanocomposite (BIIRCN and ethylene-propylene-diene-monomer rubber/clay nanocomposite (EPDMCN were prepared by melt blending. The micro-structural evolution of these two kinds of rubber/clay nanocomposites (RCNs with vulcanization process was investigated using wide-angle X-ray diffraction (WAXD and transmission electron microscope (TEM. The WAXD results revealed that the intercalated structure of organically modified clay (OMC changed throughout the whole curing process. The intercalated structure kept on changing beyond the vulcanization stage of T90. The interlayer space of intercalated silicate in uncured BIIRCN is larger than that in uncured EPDMCN. However, the intercalated structure for EPDMCN changed by a larger extent than that for BIIRCN during the vulcanization process, and the interlayer space of the intercalated structure is larger in the cured EPDMCN than that in the cured BIIRCN. It was found that the intercalant (i.e., octadecylamine, ODA for OMC could shorten the scorch time of the curing reaction, and increase the curing rate, which was attributed to the further intercalation during vulcanization. TEM results indicated that the spatial distribution of OMC is much better in BIIR (a polar rubber matrix than that in EPDM (a non-polar rubber matrix. The changes in spatial dispersion structure during vulcanization for EPDMCN and BIIRCN show different trends. In conclusion, the polarity of the rubber is the determining factor influencing the evolution of both the intercalated structure and the spatial dispersion of clay during vulcanization.

  7. FINITE ELEMENT ANALYSIS OF STRUCTURES

    Directory of Open Access Journals (Sweden)

    PECINGINA OLIMPIA-MIOARA

    2015-05-01

    Full Text Available The application of finite element method is analytical when solutions can not be applied for deeper study analyzes static, dynamic or other types of requirements in different points of the structures .In practice it is necessary to know the behavior of the structure or certain parts components of the machine under the influence of certain factors static and dynamic . The application of finite element in the optimization of components leads to economic growth , to increase reliability and durability organs studied, thus the machine itself.

  8. STATIC ANALYSIS OF CABLE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    HUANG Yan; LAN Wei-ren

    2006-01-01

    Based on the nonlinear geometric relation between strain and displacement for flexible cable, the equilibrium equation under self-weight and influence of temperature was established and an analytical solution of displacement and tension distribution defined in Eulerian coordinate system was accurately obtained. The nonlinear algebraic equations caused by cable structure were solved directly using the modified Powell hybrid algorithm with high precision routine DNEQNE of Fortran. For example, a cable structure consisting of three cables jointly supported by a vertical spring and all the other ends fixed was calculated and compared with various methods by other scholars.

  9. Accelerated protein evolution analysis reveals genes and pathways associated with the evolution of mammalian longevity

    OpenAIRE

    Li, Yang; de Magalhães, João Pedro

    2011-01-01

    The genetic basis of the large species differences in longevity and aging remains a mystery. Thanks to recent large-scale genome sequencing efforts, the genomes of multiple species have been sequenced and can be used for cross-species comparisons to study species divergence in longevity. By analyzing proteins under accelerated evolution in several mammalian lineages where maximum lifespan increased, we identified genes and processes that are candidate targets of selection when longevity evolv...

  10. Understanding the Evolution of Industrial Symbiosis Research : A Bibliometric and Network Analysis (1997-2012)

    NARCIS (Netherlands)

    Yu, Chang; Davis, Chris; Dijkema, Gerard P. J.

    2014-01-01

    This study analyzes the evolution of the research field of industrial symbiosis (IS). We elucidate its embedding in industrial ecology (IE), trace the development of research themes, and reveal the evolution of the research network through analysis of the core literature and journals that appeared f

  11. Optimization Modeling and Evolution Analysis of Beijing' s Industrial Structure under Energy Constraints%能源约束视角下北京市产业结构的优化模拟与演进分析

    Institute of Scientific and Technical Information of China (English)

    唐志鹏; 刘卫东; 付承伟; 武红

    2012-01-01

    利用北京市1987年-2007年的地区投入产出表,在能源消耗总量约束条件下构建了北京市1987年、1992年、1997年、2002年和2007年五个时期的投入产出优化模型,通过产业结构调整的手段来实现经济效益最大。通过五个历史时期的优化模拟,采用灰色关联度分析比较了各个历史时期的真实产业结构与优化产业结构的相似程度。研究表明:①北京市的产业结构调整的重点在于发展第三产业,包括批发和零售业、金融保险业和其他社会服务业部门;②除1987年外,北京市其他各时期工业调整方向需要降低大部分工业的比重,2002年和2007年则需要适度提高纺织服装鞋帽皮革羽绒制品业、通用专用设备制造业、交通运输设备制造业、电气机械及器材制造业和通信设备计算机及其他电子设备制造业的比重;③通过比较五个时期北京市产业结构的优化模拟,得出北京市1997年的产业结构优化程度最高,2002年则最低,同时数据显示北京市2002年以后的产业结构优化程度低于2002年以前,北京市产业结构优化仍旧具有较大的调整潜力。最后,提出了北京市产业结构未来调整的方向。%This study developed an input-output optimization model for Beijing under constraints of energy consumption,with the objective to maximize economic benefits by industrial structure adjustment in 1987,1992,1997,2002,and 2007,respectively,based on Beijing’s input-output tables.The similarity of the industrial structure between simulations and reality was analyzed by the grey interconnection degree method.Results show that 1)the emphasis of Beijing’s industrial structure adjustment is the development of the tertiary industry,involving increasing the proportions of three sectors,i.e.,wholesale and retail trade,finance and insurance,and other social services;2)Except 1987,the proportions of a majority of Beijing’s industries should be

  12. Insights into the evolution of the CSP gene family through the integration of evolutionary analysis and comparative protein modeling.

    Directory of Open Access Journals (Sweden)

    Jonna Kulmuni

    Full Text Available Insect chemical communication and chemosensory systems rely on proteins coded by several gene families. Here, we have combined protein modeling with evolutionary analysis in order to study the evolution and structure of chemosensory proteins (CSPs within arthropods and, more specifically, in ants by using the data available from sequenced genomes. Ants and other social insects are especially interesting model systems for the study of chemosensation, as they communicate in a highly complex social context and much of their communication relies on chemicals. Our ant protein models show how this complexity has shaped CSP evolution; the proteins are highly modifiable by their size, surface charge and binding pocket. Based on these findings, we divide ant CSPs into three groups: typical insect CSPs, an ancient 5-helical CSP and hymenopteran CSPs with a small binding pocket, and suggest that these groups likely serve different functions. The hymenopteran CSPs have duplicated repeatedly in individual ant lineages. In these CSPs, positive selection has driven surface charge changes, an observation which has possible implications for the interaction between CSPs and ligands or odorant receptors. Our phylogenetic analysis shows that within the Arthropoda the only highly conserved gene is the ancient 5-helical CSP, which is likely involved in an essential ubiquitous function rather than chemosensation. During insect evolution, the 6-helical CSPs have diverged and perform chemosensory functions among others. Our results contribute to the general knowledge of the structural differences between proteins underlying chemosensation and highlight those protein properties which have been affected by adaptive evolution.

  13. Insights into the evolution of the CSP gene family through the integration of evolutionary analysis and comparative protein modeling.

    Science.gov (United States)

    Kulmuni, Jonna; Havukainen, Heli

    2013-01-01

    Insect chemical communication and chemosensory systems rely on proteins coded by several gene families. Here, we have combined protein modeling with evolutionary analysis in order to study the evolution and structure of chemosensory proteins (CSPs) within arthropods and, more specifically, in ants by using the data available from sequenced genomes. Ants and other social insects are especially interesting model systems for the study of chemosensation, as they communicate in a highly complex social context and much of their communication relies on chemicals. Our ant protein models show how this complexity has shaped CSP evolution; the proteins are highly modifiable by their size, surface charge and binding pocket. Based on these findings, we divide ant CSPs into three groups: typical insect CSPs, an ancient 5-helical CSP and hymenopteran CSPs with a small binding pocket, and suggest that these groups likely serve different functions. The hymenopteran CSPs have duplicated repeatedly in individual ant lineages. In these CSPs, positive selection has driven surface charge changes, an observation which has possible implications for the interaction between CSPs and ligands or odorant receptors. Our phylogenetic analysis shows that within the Arthropoda the only highly conserved gene is the ancient 5-helical CSP, which is likely involved in an essential ubiquitous function rather than chemosensation. During insect evolution, the 6-helical CSPs have diverged and perform chemosensory functions among others. Our results contribute to the general knowledge of the structural differences between proteins underlying chemosensation and highlight those protein properties which have been affected by adaptive evolution. PMID:23723994

  14. Analysis of composite structural elements

    Directory of Open Access Journals (Sweden)

    A. Baier

    2010-12-01

    Full Text Available Purpose: The themes of the study are composite structural components. For this purpose have been designed and built several research positions.Design/methodology/approach: Using different structural materials to build new device components requires multiple tests of the components. Research posts were designed in the advanced graphical program CAx Siemens NX 7.5. Analysed samples were made from the glass fibre, aramid and carbon of various weights. Due to the specific use of composite materials it focuses on the elements in the form of plates and flat bars. For the examination of experimental strain gauge technique was used bead, the force sensor and displacement sensor. The experimental methods were compared with computer simulation using the FEM.Findings: The aim of this study was to determine the basic material constants and a comparison of the experimental method and the method of computer simulation.Research limitations/implications: Change the number of layers and how to connect the laminate with the steel plate changes mechanical properties of the structural component.Practical implications: The ultimate result will be knowledge on the different forms of laminates, such as material properties, the stresses in all layers, strain and comparing the results obtained by two methods.Originality/value: The expected outcome of the study will be the composition and method of joining composite laminate with a steel plate to the possible application in the repair and construction of structural elements of freight wagons.

  15. STRUCTURE EVOLUTION OF POLYMER CHAINS FOR NECKING FORMATION IN HIGH-SPEED FIBER SPINNING PROCESS

    Institute of Scientific and Technical Information of China (English)

    Hong Zheng; Wei Yu; Hong-bin Zhang; Chi-xing Zhou

    2006-01-01

    Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions. The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.

  16. Structural analysis of DNA by autoradiography

    International Nuclear Information System (INIS)

    During the past 10 years, molecular biology has rapidly been developing owing to easy structural analysis of DNA, a fundamental substance involved in life function. The application of highly sensitive RI with the production of large amounts of DNA and with no change in the chemical property of the substance to be tested has greatly contributed to molecular biology. For the development of life science and biotechnology, it is essential to analyze basic arrangement of DNA, identify genes, predict amino acid arrangement of proteins, and clarify regulation mechanism involved in genes. To understand DNA function sufficiently, analysis of secondary or tertiary structure, as well as primary structure of DNA, is extremely important. In this paper, the primary DNA structural analysis is provided in relation to RI application. Structural analysis of DNA can be classified into (1) hybridization method and (2) basic arrangement determination method. The application of DNA analysis is discussed in terms of the following: (1) varified analysis of the antibody, (2) isolation and analysis of carcinogenic genes, and (3) gene diagnosis. There is a problem with manual process in the structural analysis of DNA. Currently, automatic apparatuses for extraction, purification, reaction, isolation, and detection of DNA have been developing. (N.K.)

  17. Advanced X-Ray scattering methods for the study of structure and its evolution in soft materials with fiber symmetry

    International Nuclear Information System (INIS)

    Three recently developed evaluation methods for the automated quantitative analysis of X-ray scattering data (small-angle (SAXS) and wide-angle (WAXS)) are presented. They are applicable to extensive series of 2D patterns that are recorded in studies of polymer materials with uniaxial symmetry. The experiments comprise time-resolved studies (melting, crystallization, mechanical properties and fatigue) as well as microbeam-scanning for the study of nanostructure gradients. The methods appear suitable to manage the data flood from modern synchrotron radiation setups aiming at the extraction of quantitative information on the structure evolution inside the material. In microbeam-scanning experiments the recorded scattering patterns are smeared. It is proposed to reconstruct desmeared scattering patterns by an X-ray scattering fiber-computer-tomography (XS-FCT). Reconstruction aberrations yield additional structure information. The true structure variation along the fiber radius is established. Compared to general tomography the experiment is faster by a factor of 100, and reconstruction is faster by a factor of 104. In WAXS fiber patterns should first be mapped into reciprocal space before analysis. After having corrected an erroneous tilt-angle equation, automatic tilt-angle tracking and mapping becomes possible. If polymers fail at low strain, the determination of strain and of structural parameters from the scattering patterns require very high accuracy because the observed variations are subtle. Suitable methods are presented both for the high-precision determination of the macroscopic strain, and for the determination of subtle variations of structure parameters.

  18. An empirical formulation to describe the evolution of the high burnup structure

    Science.gov (United States)

    Lemes, Martín; Soba, Alejandro; Denis, Alicia

    2015-01-01

    In the present work the behavior of fuel pellets for LWR power reactors in the high burnup range (average burnup higher than about 45 MWd/kgU) is analyzed. For extended irradiation periods, a considerable Pu concentration is reached in the pellet periphery (rim zone), that contributes to local burnup. Gradually, a new microstructure develops in that ring, characterized by small grains and large pores as compared with those of the original material. In this region Xe is absent from the solid lattice (although it continues to be dissolved in the rest of the pellet). The porous microstructure in the pellet edge causes local changes in the mechanical and thermal properties, thus affecting the overall fuel behavior. It is generally accepted that the evolution of porosity in the high burnup structure (HBS) is determinant of the retention capacity of the fission gases rejected from the fuel matrix. This is the reason why, during the latest years a considerable effort has been devoted to characterizing the parameters that influence porosity. Although the mechanisms governing the microstructural transformation have not been completely elucidated yet, some empirical expressions can be given, and this is the intention of the present work, for representing the main physical parameters. Starting from several works published in the open literature, some mathematical expressions were developed to describe the behavior and progress of porosity at local burnup values ranging from 60 to 300 MWd/kgU. The analysis includes the interactions of different orders between pores, the growth of the pore radius by capturing vacancies, the evolution of porosity, pore number density and overpressure within the closed pores, the inventory of fission gas dissolved in the matrix and retained in the pores. The model is mathematically expressed by a system of non-linear differential equations. In the present work, results of this calculation scheme are compared with experimental data available in

  19. A Comprehensive study of Cavities on the Sun: Structure, Formation, and Evolution

    Science.gov (United States)

    Karna, Nishu; Zhang, Jie; Pesnell, William D.

    2016-05-01

    Coronal cavities are large-scale structures in the Sun's corona that are closely related with the long-term evolution of the magnetic field in the photosphere as well as associated with the energetic solar activity such as prominence eruptions and coronal mass ejections. They are observed as circular or elliptical-shaped relatively low-density dark regions above the solar limb in EUV, X-ray, and white-light coronal images. We used SDO/AIA limb synoptic maps, constructed from annuli above the solar limb, to systematically identify cavities. We observed 429 coronal prominence cavities between May 20, 2010 and Feb 1, 2015. We examined correlations between height, width, and length of the cavities. Based on the fitting of the shape of the cross section, we classified cavities in three types: prolate (38%), oblate (27%) and circular (35%). We found that the cavities of all shapes are common in shorter length while circular and oblate cavities are more common in the longer length. In general, we found that the overall 3-D topology of long stable cavities can be characterized as a long tube with an elliptical cross-section. Next, we investigated the pattern of cavity location and found that cavity systematically drifts towards the pole. We found that cavities form a belt by making a plot using SDO/HMI surface magnetogram similar to classical buttery diagram of sunspots, we call that the cavity belt. Our analysis showed that the cavity belts migrated towards higher latitude with time and the cavity belts disappeared after the polar magnetic field reversal. This result shows that cavity evolution provides new insight into the solar cycle. Moreover, we studied the underlying magnetic field of a circumpolar crown cavity (Mar 21, 2013- Oct 25, 2013) that was observed for several Carrington Rotations. Our results showed that the underlying polarity inversion line of cavities is formed between the trailing part of decayed active regions and the unipolar magnetic field in the

  20. An empirical formulation to describe the evolution of the high burnup structure

    Energy Technology Data Exchange (ETDEWEB)

    Lemes, Martín; Soba, Alejandro; Denis, Alicia

    2015-01-15

    In the present work the behavior of fuel pellets for LWR power reactors in the high burnup range (average burnup higher than about 45 MWd/kgU) is analyzed. For extended irradiation periods, a considerable Pu concentration is reached in the pellet periphery (rim zone), that contributes to local burnup. Gradually, a new microstructure develops in that ring, characterized by small grains and large pores as compared with those of the original material. In this region Xe is absent from the solid lattice (although it continues to be dissolved in the rest of the pellet). The porous microstructure in the pellet edge causes local changes in the mechanical and thermal properties, thus affecting the overall fuel behavior. It is generally accepted that the evolution of porosity in the high burnup structure (HBS) is determinant of the retention capacity of the fission gases rejected from the fuel matrix. This is the reason why, during the latest years a considerable effort has been devoted to characterizing the parameters that influence porosity. Although the mechanisms governing the microstructural transformation have not been completely elucidated yet, some empirical expressions can be given, and this is the intention of the present work, for representing the main physical parameters. Starting from several works published in the open literature, some mathematical expressions were developed to describe the behavior and progress of porosity at local burnup values ranging from 60 to 300 MWd/kgU. The analysis includes the interactions of different orders between pores, the growth of the pore radius by capturing vacancies, the evolution of porosity, pore number density and overpressure within the closed pores, the inventory of fission gas dissolved in the matrix and retained in the pores. The model is mathematically expressed by a system of non-linear differential equations. In the present work, results of this calculation scheme are compared with experimental data available in

  1. Structure of technology evolution: The way on which ICT industry emerged in Korea

    OpenAIRE

    Kim, Kibae; Jung, Sungdo; Lee, Changjun; Hwang, Junseok

    2013-01-01

    The role of ICT in the economic growth in Korea is a great attraction to the telecommunication society interested in the relationship among ICT, innovation policy and economic growth. However, prior research concentrates on investigating the effect of policy on innovation and economic growth, but misses the mechanism how a policy affects the technological system which interacts with public institutes, universities and private firms. In this paper, we analyze the structure of technology evolut...

  2. Vertical Moist Thermodynamic Structure and Spatial–Temporal Evolution of the MJO in AIRS Observations

    OpenAIRE

    Tian, Baijun; Waliser, Duane E.; Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Yung, Yuk L.; Wang, Bin

    2006-01-01

    The atmospheric moisture and temperature profiles from the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit on the NASA Aqua mission, in combination with the precipitation from the Tropical Rainfall Measuring Mission (TRMM), are employed to study the vertical moist thermodynamic structure and spatial–temporal evolution of the Madden–Julian oscillation (MJO). The AIRS data indicate that, in the Indian Ocean and western Pacific, the temperature anomaly exhibits a trimodal ve...

  3. Measurement of reaction rates of interest in stellar structure and evolution

    Energy Technology Data Exchange (ETDEWEB)

    Terrasi, F.; D`Onofrio, A. [Dipt. di Scienze Ambientali, Seconda Univ. di Napoli, Caserta (Italy)]|[INFN, Napoli (Italy); Campajola, L.; Imbriani, G. [INFN, Napoli (Italy)]|[Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); Gialanella, L. [INFN, Napoli (Italy)]|[Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy)]|[Inst. fuer Experimentalphysik III, Ruhr-Univ. Bochum, Bochum (Germany); Greife, U.; Rolfs, C.; Strieder, F.; Trautvetter, H.P. [Inst. fuer Experimentalphysik III, Ruhr-Univ. Bochum, Bochum (Germany); Roca, V.; Romano, M. [INFN, Napoli (Italy)]|[Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); Straniero, O. [Osservatorio Astronomico di Collurania, Teramo (Italy)

    1998-06-01

    Accurate determinations of reaction rates at astrophysical energies are very important in stellar structure and evolution studies. The cases of two key reactions, namely {sup 7}Be(p,{gamma}){sup 8}B and {sup 12}C({alpha},{gamma}){sup 16}O are discussed, both from the point of view of their astrophysical interest and of the experimental difficulties in the measurement of their cross section. (orig.)

  4. Structural evolution of biomass char and its effect on the gasification rate

    DEFF Research Database (Denmark)

    Fatehi, Hesameddin; Bai, Xue Song

    2016-01-01

    The evolution of char porous structure can affect the conversion rate of the char by affecting the intra-particle transport, especially in the zone II conversion regime. A multi-pore model based on the capillary pore theory is developed to take into account different conversion rates for pores......-pore model accommodates the detailed intra-particle transport, it is a useful basis toward developing a more predictive model for biomass char gasification....

  5. Independent Effects of Protein Core Size and Expression on Residue-Level Structure-Evolution Relationships

    OpenAIRE

    Franzosa, Eric A.; Yu Xia

    2012-01-01

    Recently, we demonstrated that yeast protein evolutionary rate at the level of individual amino acid residues scales linearly with degree of solvent accessibility. This residue-level structure-evolution relationship is sensitive to protein core size: surface residues from large-core proteins evolve much faster than those from small-core proteins, while buried residues are equally constrained independent of protein core size. In this work, we investigate the joint effects of protein core size ...

  6. Bi-Hamiltonian Structure of a Third-Order Nonlinear Evolution Equation on Plane Curve Motions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the present paper, we identify the integrability of the third-order nonlinear evolution equation ut = (1/2)((uxx + u)-2)x in a Hamiltonian viewpoint. We prove that the recursion operator obtained by S. Yu. Sakovich is hereditary, and then deduce a bi-Hamiltonian structure of the equation by using some decomposition of the hereditary operator. A hierarchy associated to the equation is also shown.

  7. Community structure and the evolution of interdisciplinarity in Slovenia's scientific collaboration network

    OpenAIRE

    Lužar, Borut; Levnajić, Zoran; Povh, Janez; Perc, Matjaž

    2014-01-01

    Interaction among the scientific disciplines is of vital importance in modern science. Focusing on the case of Slovenia, we study the dynamics of interdisciplinary sciences from 1960 to 2010. Our approach relies on quantifying the interdisciplinarity of research communities detected in the coauthorship network of Slovenian scientists over time. Examining the evolution of the community structure, we find that the frequency of interdisciplinary research is only proportional with the overall gro...

  8. Small-angle neutron scattering study of structural evolution of different phases in protein solution

    Indian Academy of Sciences (India)

    V K Aswal; S Chodankar; J Kohlbrecher; R Vavrin; A G Wagh

    2008-10-01

    Small-angle neutron scattering (SANS) has been used to study the structural evolution of different phases in protein solution leading to crystallization, denaturation and gelation. The protein solution under crystallization mostly consists of monomers and dimers, and higher-mers are not observed as they are perhaps formed in very small numbers. The onset and the rate of crystallization strongly depend on the salt concentration. Protein denaturation on addition of surfactant occurs due to the formation of micelle-like clusters along the unfolded polypeptide chains of the protein. The structure of such protein{surfactant complex is found to be independent of the size of the micelles in their pure surfactant solutions. The structure of temperature-induced protein gels shows a fractal structure. Rheology of these gels shows a strong dependence on varying pH or protein concentration, whereas the structure of such gels is found to be similar.

  9. Photoelectron velocity-map imaging signature of structural evolution of silver-doped lead Zintl anions.

    Science.gov (United States)

    Xie, Hua; Qin, Zhengbo; Wu, Xia; Tang, Zichao; Jiang, Ling

    2012-08-14

    A set of silver-doped lead Zintl anions, Ag@Pb(n)(-) (n = 5-12), have been studied using photoelectron velocity-map imaging spectroscopy and quantum chemical calculation. The structures of Ag@Pb(n)(-) (n = 7-9, 11) built upon a square pyramid base, hitherto not considered, were assigned. Overall agreement between the experimental and calculated photoelectron spectra as well as vertical detachment energies allows for structural evolution to be established. The silver atom prefers to stay outside in the n ≤ 6 clusters and intends to be encapsulated by the lead atoms in n > 6. A stable endohedral cage with bicapped square antiprism structure is formed at n = 10, the endohedral structure of which persists for the larger clusters. Especially, these Ag@Pb(n)(-) anions have been found to undergo a transition between square pyramid and pentagonal pyramid molecular structures at n = 11. PMID:22897284

  10. Robustness Analysis of Timber Truss Structure

    DEFF Research Database (Denmark)

    Rajčić, Vlatka; Čizmar, Dean; Kirkegaard, Poul Henning;

    2010-01-01

    The present paper discusses robustness of structures in general and the robustness requirements given in the codes. Robustness of timber structures is also an issues as this is closely related to Working group 3 (Robustness of systems) of the COST E55 project. Finally, an example of a robustness...... evaluation of a widespan timber truss structure is presented. This structure was built few years ago near Zagreb and has a span of 45m. Reliability analysis of the main members and the system is conducted and based on this a robustness analysis is preformed....

  11. Structural analysis of the Jebel Fadeloun anticline, Tunisia: Impact of fractures and faults on the petrophysical properties of carbonate rocks

    OpenAIRE

    Kjelkenes, Fredrik Sebastian

    2015-01-01

    Recognizing the structure, evolution and fluid flow within the earth's crust is a critical issue for both academic and applied geoscience. This study presents structural analysis of an anticline, which aim is to elucidate the (1) structure and evolution of the fold, as well as the associated faults and fractures, (2) to better investigate how tectonics have impacted the microstructural character of the host rock, and (3) to discuss possible implications for petro...

  12. Evolution of structure with Fe layer thickness in low dimensional Fe/Tb multilayered structures

    International Nuclear Information System (INIS)

    This paper reports on the atomic structure of a series of low-dimensional Fe/Tb multilayered structures which has been explored using a conversion-electron, extended x-ray absorption fine structure (EXAFS) technique. A structural transition from a close-packed amorphous structure to a body-centered crystalline structure is detected to occur over an Fe layer thickness range of 12.5 Angstrom to 15.0 Angstrom (Tb thickness is held constant at 4.5 Angstrom). Magnetic properties, specifically, magnetization, anisotropy field, and Kerr rotation angle, are measured and found to change significantly in response to this transition. Exploitation of the polarization properties of synchrotron radiation allowed for the description of the atomic structure both perpendicular and parallel to the sample plane

  13. Finite Element Analysis and Understanding the Biomechanics and Evolution of Living and Fossil Organisms

    Science.gov (United States)

    Rayfield, Emily J.

    2007-05-01

    Finite element analysis (FEA) is a technique that reconstructs stress, strain, and deformation in a digital structure. Although commonplace in engineering and orthopedic science for more than 30 years, only recently has it begun to be adopted in the zoological and paleontological sciences to address questions of organismal morphology, function, and evolution. Current research tends to focus on either deductive studies that assume a close relationship between form and function or inductive studies that aim to test this relationship, although explicit hypothesis-testing bridges these two standpoints. Validation studies have shown congruence between in vivo or in vitro strain and FE-inferred strain. Future validation work on a broad range of taxa will assist in phylogenetically bracketing our extinct animal FE-models to increase confidence in our input parameters, although currently, FEA has much potential in addressing questions of form-function relationships, providing appropriate questions are asked of the existing data.

  14. NAPS: Network Analysis of Protein Structures.

    Science.gov (United States)

    Chakrabarty, Broto; Parekh, Nita

    2016-07-01

    Traditionally, protein structures have been analysed by the secondary structure architecture and fold arrangement. An alternative approach that has shown promise is modelling proteins as a network of non-covalent interactions between amino acid residues. The network representation of proteins provide a systems approach to topological analysis of complex three-dimensional structures irrespective of secondary structure and fold type and provide insights into structure-function relationship. We have developed a web server for network based analysis of protein structures, NAPS, that facilitates quantitative and qualitative (visual) analysis of residue-residue interactions in: single chains, protein complex, modelled protein structures and trajectories (e.g. from molecular dynamics simulations). The user can specify atom type for network construction, distance range (in Å) and minimal amino acid separation along the sequence. NAPS provides users selection of node(s) and its neighbourhood based on centrality measures, physicochemical properties of amino acids or cluster of well-connected residues (k-cliques) for further analysis. Visual analysis of interacting domains and protein chains, and shortest path lengths between pair of residues are additional features that aid in functional analysis. NAPS support various analyses and visualization views for identifying functional residues, provide insight into mechanisms of protein folding, domain-domain and protein-protein interactions for understanding communication within and between proteins. URL:http://bioinf.iiit.ac.in/NAPS/. PMID:27151201

  15. Structural Characteristics and Evolution of Jurassic Basins in the East of Middle Qilian Block

    Institute of Scientific and Technical Information of China (English)

    郑孟林; 李明杰; 曹春潮; 张勇军; 徐世陆

    2003-01-01

    Structural characteristics of the Jurassic basins of Xining, Minhe, and Xiji in the east of middle Qilian were researched based on the data obtained by gravitational, magnetic, and seismic methods. The result shows that each of these three basins is an independent structural unit with a NW strike and being separated by upheavals. Two groups of faults with NW and NE directions are developed in the basin, which controls the formation and evolution of the (Jurassic basins). The NW faults are the main ones while the NE faults are the secondary for controlling the sedimentation. Of the three basins, the Minhe basin is the favorable prospecting area.

  16. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    Energy Technology Data Exchange (ETDEWEB)

    Gargarella, P., E-mail: piter@ufscar.br [IFW Dresden, Institut für Komplexe Materialien, Helmholtzstraße 20, D-01069 Dresden (Germany); Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rodovia Washington Luiz, Km 235, 13565-905 São Carlos, São Paulo (Brazil); Pauly, S.; Stoica, M.; Kühn, U. [IFW Dresden, Institut für Komplexe Materialien, Helmholtzstraße 20, D-01069 Dresden (Germany); Vaughan, G. [European Synchrotron Radiation Facilities, BP 220, 38043 Grenoble (France); Afonso, C. R. M. [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rodovia Washington Luiz, Km 235, 13565-905 São Carlos, São Paulo (Brazil); Eckert, J. [IFW Dresden, Institut für Komplexe Materialien, Helmholtzstraße 20, D-01069 Dresden (Germany); Institut für Werkstoffwissenschaft, Technische Universität Dresden, D-01062 Dresden (Germany)

    2015-01-01

    The structural evolution of Ti{sub 50}Cu{sub 43}Ni{sub 7} and Ti{sub 55}Cu{sub 35}Ni{sub 10} metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  17. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    Science.gov (United States)

    Gargarella, P.; Pauly, S.; Stoica, M.; Vaughan, G.; M. Afonso, C. R.; Kühn, U.; Eckert, J.

    2015-01-01

    The structural evolution of Ti50Cu43Ni7 and Ti55Cu35Ni10 metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  18. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    Directory of Open Access Journals (Sweden)

    P. Gargarella

    2015-01-01

    Full Text Available The structural evolution of Ti50Cu43Ni7 and Ti55Cu35Ni10 metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  19. STRUCTURE EVOLUTION OF THE CYLINDRICAL PHASE OF DIBLOCK COPOLYMERS IN FILMS

    Institute of Scientific and Technical Information of China (English)

    Hong-ge Tan; Zi-yu Wang; Wen-fang Zhu; Qing-gong Song; Hui Li; Cui-qin Bai

    2008-01-01

    In the weak segregation limit,the structure evolution of the hexagonal cylindrical phase of diblock copolymers in films was investigated.Employing the Landau-Brazovskii mean field theory,we obtained three amplitude parameters as functions of temperature,surface field strength and film thickness.By controlling confinement size and surface field strength,lamellae and undulated lamellae appear in the cylindrical bulk phase of diblock copolymers."Phase diagrams" of confinement-induced structures are constructed at different surface field strengths.The obtained theoretical results are in agreement with relevant theoretical and experimental results.

  20. Media as the mechanism behind structural coupling and the evolution of the mind

    DEFF Research Database (Denmark)

    Tække, Jesper

    for how the structural coupling is possible through the medium of language. The paper put forward an angle on the subject, which makes it probable that language let the two levels of systems formation emerge, because it enables their respective self-reference, so they can maintain themselves...... of the becoming of the psychic self. After this becoming other media of communication, as mechanisms behind the structural coupling, through the history of evolution has made a continuous increase of complexity, on both sides of the distinction between the psychic and the social, possible. This would be too much...

  1. Seismic Structure and Geodynamic Evolution of the Lithosphere and Upper Mantle in the Pannonian - Carpathian Region

    Science.gov (United States)

    Houseman, G.; Stuart, G.; Dando, B.; Hetenyi, G.; Lorinczi, P.; Brueckl, E.; Hegedus, E.; Radovanovic, S.; Brisbourne, A.

    2009-04-01

    The Pannonian Basin is the largest of a group of Miocene-age extensional basins within the arc of the Alpine-Carpathian Mountain Ranges. These basins are extensional in origin, but the surrounding Carpathians result from sustained convergence during and since the period of active extension. A significant part of the mantle lithosphere here has been replaced, as gravitational instability caused an overturn of the upper mantle. The Carpathian Basins Project (CBP) is a major international broadband seismology experiment, supported by geodynamical modelling and designed to improve our understanding of the structure and evolution of the lithosphere and upper mantle beneath the Pannonian and Vienna Basins. Between 2005 and 2007 we deployed 56 portable broadband seismic stations in Austria, Hungary and Serbia, spanning the Vienna Basin and the western part of the Pannonian Basin. Arrival time residuals from teleseismic earthquakes are delayed by about 0.8 sec in the Vienna Basin and early by a similar amount in southwest Hungary. Tomographic inversion of the travel time residuals shows relatively fast P-wave velocities in the upper mantle beneath the western Pannonian Basin and slow P-wave velocities beneath the West Carpathians. Seismic anisotropy (SKS) measurements reveal an intriguing pattern of lithospheric anisotropy: in the north-west the fast direction is generally elongated EW, perpendicular to the shortening direction across the Alps. Across the Vienna Basin the fast direction is NW-SE, perpendicular to the major bounding fault systems. Across the Pannonian Basin the dominant fast direction is EW, but in several locations the vectors are rotated toward NW-SE. The Mid-Hungarian Line, a major strike-slip structure already clearly identified in the gravity field, also is associated with abrupt changes in the azimuth of lithospheric anisotropy. Receiver function analysis of the seismic discontinuity at 670 km shows significant structure on scales of order 100 km, and

  2. A model for the evolution of the Earth's mantle structure since the Early Paleozoic

    Science.gov (United States)

    Zhang, Nan; Zhong, Shijie; Leng, Wei; Li, Zheng-Xiang

    2010-06-01

    Seismic tomography studies indicate that the Earth's mantle structure is characterized by African and Pacific seismically slow velocity anomalies (i.e., superplumes) and circum-Pacific seismically fast anomalies (i.e., a globally spherical harmonic degree 2 structure). However, the cause for and time evolution of the African and Pacific superplumes and the degree 2 mantle structure remain poorly understood with two competing proposals. First, the African and Pacific superplumes have remained largely unchanged for at least the last 300 Myr and possibly much longer. Second, the African superplume is formed sometime after the formation of Pangea (i.e., at 330 Ma) and the mantle in the African hemisphere is predominated by cold downwelling structures before and during the assembly of Pangea, while the Pacific superplume has been stable for the Pangea supercontinent cycle (i.e., globally a degree 1 structure before the Pangea formation). Here, we construct a proxy model of plate motions for the African hemisphere for the last 450 Myr since the Early Paleozoic using the paleogeographic reconstruction of continents constrained by paleomagnetic and geological observations. Coupled with assumed oceanic plate motions for the Pacific hemisphere, this proxy model for the plate motion history is used as time-dependent surface boundary condition in three-dimensional spherical models of thermochemical mantle convection to study the evolution of mantle structure, particularly the African mantle structure, since the Early Paleozoic. Our model calculations reproduce well the present-day mantle structure including the African and Pacific superplumes and generally support the second proposal with a dynamic cause for the superplume structure. Our results suggest that while the mantle in the African hemisphere before the assembly of Pangea is predominated by the cold downwelling structure resulting from plate convergence between Gondwana and Laurussia, it is unlikely that the bulk of

  3. Structure stability and configuration evolution of Aln (n=3, 4, 6, 13, 19) clusters

    Institute of Scientific and Technical Information of China (English)

    PENG Ping; LI Guifa; ZHENG Caixing; HAN Shaochang; LIU Rangsu

    2006-01-01

    Using a first-principles pseudo-potential plane wave method, the geometrical and electronic structures of Aln (n=3, 4, 6, 13, 19) clusters with different configurations have been calculated. Several parameters such as the binding energy Eb and the HOMO-LUMO energy gap △EH-L have been adopted to characterize and analyze the structure stability of these clusters, and their configuration evolutions are also investigated by linear synchronous transit (LST) method. It is demonstrated that the stable configurations of Al3, Al4, Al6, Al13, Al19 clusters are triangle, rhombus, octahedron, icosahedron and double icosahedron, respectively. For Al6 and Al19 clusters there are metastable structures of parallelogram and octahedron, respectively, whereas in the Al3, Al4 and Al13 clusters, no metastable configuration is validated. There exist a large energy gap and a low energy barrier between the octahedron and the parallelogram of the Al6 cluster, so the transformation from its metastable to stable structures is rather easy. By contrast, a small energy gap and a high energy barrier between the stable and metastable structures of Al19 cluster mean its configuration evolution from the octahedron to the double icosahedron occurs hardly, therefore the metastable octahedron configuration of Al19 cluster can be extensively detected in experiments and simulations.

  4. Evolution of kinetically controlled In-induced surface structure on Si(5 5 7) surface

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Amit Kumar Singh [Physics of Energy Harvesting, (CSIR-NPL), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Department of Physics, JMI, New Delhi 110025 (India); Eldose, Nirosh M.; Mishra, Monu [Physics of Energy Harvesting, (CSIR-NPL), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Niazi, Asad; Nair, Lekha [Department of Physics, JMI, New Delhi 110025 (India); Gupta, Govind, E-mail: govind@nplindia.org [Physics of Energy Harvesting, (CSIR-NPL), Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2014-09-30

    Highlights: • Evolution of In induced superstructures on Si(5 5 7) surface during RT and HT adsorption/desorption process. • Kinetics is governed by substrate temperature which exhibits various growth modes (FM, SK, VB) under different conditions. • Strain relaxation play significant role in the commencement of desorption/rearrangement of atoms. • A consolidated phase diagram of In/Si(5 5 7) interface has been reported with new √3 × √3-R30° and 4 × 1 phases. - Abstract: This paper introduces issue of kinetically controlled and temperature driven superstructural phase transition of Indium (In) on atomically clean high index Si(5 5 7)-7 × 1 surface. Auger electron spectroscopy analysis reveals that at room-temperature (RT) with a controlled incident flux of 0.002 ML/s; In overlayers evolve through the Frank-van der Merwe growth mode and yield a (1 × 1) diffraction pattern for coverage ≥1 ML. For substrate temperature <500°C, growth of In follows Stranski–Krastanov growth mode while for temperature >500°C island growth is observed. On annealing the In/Si(5 5 7) interface in the temperature range 250–340°C, clusters to two dimensional (2D) layer transformation on top of a stable monolayer is predominated. In-situ RT and HT adsorption and thermal desorption phenomena revealed the formation of coverage and temperature dependent thermally stable In induced superstructural phases such as (4 × 1) at 0.5 ML (520°C), (√3 × √3-R30°) at 0.3 ML (560°C) and (7 × 7) at 0.1 ML (580°C). These indium induced superstructures could be utilized as potential substrate for the growth of various exotic 1D/2D structures.

  5. Structural Dynamics and Data Analysis

    Science.gov (United States)

    Luthman, Briana L.

    2013-01-01

    This project consists of two parts, the first will be the post-flight analysis of data from a Delta IV launch vehicle, and the second will be a Finite Element Analysis of a CubeSat. Shock and vibration data was collected on WGS-5 (Wideband Global SATCOM- 5) which was launched on a Delta IV launch vehicle. Using CAM (CAlculation with Matrices) software, the data is to be plotted into Time History, Shock Response Spectrum, and SPL (Sound Pressure Level) curves. In this format the data is to be reviewed and compared to flight instrumentation data from previous flights of the same launch vehicle. This is done to ensure the current mission environments, such as shock, random vibration, and acoustics, are not out of family with existing flight experience. In family means the peaks on the SRS curve for WGS-5 are similar to the peaks from the previous flights and there are no major outliers. The curves from the data will then be compiled into a useful format so that is can be peer reviewed then presented before an engineering review board if required. Also, the reviewed data will be uploaded to the Engineering Review Board Information System (ERBIS) to archive. The second part of this project is conducting Finite Element Analysis of a CubeSat. In 2010, Merritt Island High School partnered with NASA to design, build and launch a CubeSat. The team is now called StangSat in honor of their mascot, the mustang. Over the past few years, the StangSat team has built a satellite and has now been manifested for flight on a SpaceX Falcon 9 launch in 2014. To prepare for the final launch, a test flight was conducted in Mojave, California. StangSat was launched on a Prospector 18D, a high altitude rocket made by Garvey Spacecraft Corporation, along with their sister satellite CP9 built by California Polytechnic University. However, StangSat was damaged during an off nominal landing and this project will give beneficial insights into what loads the CubeSat experienced during the crash

  6. Dynamic analysis and design of offshore structures

    CERN Document Server

    Chandrasekaran, Srinivasan

    2015-01-01

    This book  attempts to provide readers with an overall idea of various types of offshore platform geometries. It covers the various environmental loads encountered by these structures, a detailed description of the fundamentals of structural dynamics in a class-room style, estimate of damping in offshore structures and their applications in the preliminary analysis and design. Basic concepts of structural dynamics are emphasized through simple illustrative examples and exercises. Design methodologies and guidelines, which are FORM based concepts are explained through a few applied example structures. Each chapter also has tutorials and exercises for self-learning. A dedicated chapter on stochastic dynamics will help the students to extend the basic concepts of structural dynamics to this advanced domain of research. Hydrodynamic response of offshore structures with perforated members is one of the recent research applications, which is found to be one of the effective manner of retrofitting offshore structur...

  7. Structure of Marketing Planning: A Reflective Analysis

    OpenAIRE

    Luciano Augusto Toledo; Adriana Beatriz Madeira; Guilherme Farias Shiraishi; Marcos Garber

    2014-01-01

    This study aims to promote a reflective analysis about the action planning structure in the marketing context. The work was structured in the form of essay and presents the theoretical aspects about the Marketing Planning. The intention of the article is to provide critical insights into the needs of planning marketing activities. For this purpose the document is organized as of an introduction that contextualizes the subject, accompanied by a critical analysis. Finally, the final considerati...

  8. Analysis model of structure-HDS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Presents the model established for Structure-HDS(hydraulic damper system) analysis on the basis of the theoretical analysis model of non-compressed fluid in the round pipe will an uniform velocity used as the basic variable, and pressure losses resulting from cross section changes of fluid route taken into consideration. Which provides necessary basis for researches on earthquake responses of a structure with a spacious first story, equipped with HDS at first floor.

  9. Structural analysis of impeller for SMART MCP

    International Nuclear Information System (INIS)

    The structural integrity of the MCP impeller is important for the safe and reliable operation of the SMART, since the impeller is operated for long period inside the reactor under high pressure and high temperature. In this study, an analysis model to evaluate the structural integrity of axial pump impeller has been developed and the stress state in the impeller of SMART MCP has been calculated for the applied centrifugal and hydraulic forces. The structural integrity of the impeller has been demonstrated by comparing the analysis results with the allowable stresses. The modal analysis of the impeller has been also performed to investigate the possibility of the resonances of the impeller blades with the rotational frequencies. As a means to reduce the time required for the analysis, a cyclic symmetric analysis model with optimum boundary conditions is proposed by comparing the results from full model analyses

  10. Computational structural analysis and finite element methods

    CERN Document Server

    Kaveh, A

    2014-01-01

    Graph theory gained initial prominence in science and engineering through its strong links with matrix algebra and computer science. Moreover, the structure of the mathematics is well suited to that of engineering problems in analysis and design. The methods of analysis in this book employ matrix algebra, graph theory and meta-heuristic algorithms, which are ideally suited for modern computational mechanics. Efficient methods are presented that lead to highly sparse and banded structural matrices. The main features of the book include: application of graph theory for efficient analysis; extension of the force method to finite element analysis; application of meta-heuristic algorithms to ordering and decomposition (sparse matrix technology); efficient use of symmetry and regularity in the force method; and simultaneous analysis and design of structures.

  11. Entity Authentication:Analysis using Structured Intuition

    DEFF Research Database (Denmark)

    Ahmed, Naveed; Jensen, Christian D.

    2010-01-01

    In this paper, we propose a new method for the analysis that uses intuition of the analyst in a structured way. First we define entity authentication in terms of fine level authentication goals (FLAGs). Then we use some relevant structures in protocol narrations and use them to justify FLAGs for...

  12. Group theory analysis of braided geometry structures

    Institute of Scientific and Technical Information of China (English)

    FENG Wei; MA Wensuo

    2005-01-01

    The braided geometry structures are analyzed with point groups and space groups for which the continuous yarn of the braided preforms is segmented and expressed in some special symbols. All structures of braided material are described and classified with group theory, and new braiding methods are found. The group theory analysis lays the theoretical foundation for optimizing material performance.

  13. Using rhetorical structure in sentiment analysis

    NARCIS (Netherlands)

    Hogenboom, Alexander; Frasincar, Flavius; Jong, de Franciska; Kaymak, Uzay

    2015-01-01

    Automated sentiment analysis has become an active field of study with a broad applicability. One of the key open research issues lies in dealing with structural aspects of text when analyzing its conveyed sentiment. Recent work uses structural aspects of text in order to distinguish important text s

  14. Generalized Structured Component Analysis with Latent Interactions

    Science.gov (United States)

    Hwang, Heungsun; Ho, Moon-Ho Ringo; Lee, Jonathan

    2010-01-01

    Generalized structured component analysis (GSCA) is a component-based approach to structural equation modeling. In practice, researchers may often be interested in examining the interaction effects of latent variables. However, GSCA has been geared only for the specification and testing of the main effects of variables. Thus, an extension of GSCA…

  15. Cluster Structure in Cosmological Simulations. I. Correlation to Observables, Mass Estimates, and Evolution

    Science.gov (United States)

    Jeltema, Tesla E.; Hallman, Eric J.; Burns, Jack O.; Motl, Patrick M.

    2008-07-01

    We use Enzo, a hybrid Eulerian adaptive mesh refinement/N-body code including nongravitational heating and cooling, to explore the morphology of the X-ray gas in clusters of galaxies and its evolution in current-generation cosmological simulations. We employ and compare two observationally motivated structure measures: power ratios and centroid shift. Overall, the structure of our simulated clusters compares remarkably well to low-redshift observations, although some differences remain that may point to incomplete gas physics. We find no dependence on cluster structure in the mass-observable scaling relations, TX-M and YX-M, when using the true cluster masses. However, estimates of the total mass based on the assumption of hydrostatic equilibrium, as assumed in observational studies, are systematically low. We show that the hydrostatic mass bias strongly correlates with cluster structure and, more weakly, with cluster mass. When the hydrostatic masses are used, the mass-observable scaling relations and gas mass fractions depend significantly on cluster morphology, and the true relations are not recovered even if the most relaxed clusters are used. We show that cluster structure, via the power ratios, can be used to effectively correct the hydrostatic mass estimates and mass scaling relations, suggesting that we can calibrate for this systematic effect in cosmological studies. Similar to observational studies, we find that cluster structure, particularly centroid shift, evolves with redshift. This evolution is mild but will lead to additional errors at high redshift. Projection along the line of sight leads to significant uncertainty in the structure of individual clusters: less than 50% of clusters which appear relaxed in projection based on our structure measures are truly relaxed.

  16. First steps in eukaryogenesis: Physical phenomena in the origin and evolution of chromosome structure

    International Nuclear Information System (INIS)

    Our present understanding of the origin and evolution of chromosomes differs considerably from current understanding of the origin and evolution of the cell itself. Chromosome origins have been less prominent in research, as the emphasis has not shifted so far appreciably from the phenomenon of primeval nucleic acid encapsulation to that of the origin of gene organization, expression, and regulation. In this work we discuss some reasons why preliminary steps in this direction are being taken. We have been led to examine properties that have contributed to raise the ancestral prokaryotic programmes to a level where we can appreciate in eukaryotes a clear departure from earlier themes in the evolution of cell from the last common ancestor. We shift our point of view from evolution of cell morphology to the point of view of the genes. In particular we focus attention on possible physical bases for the way transmission of information has evolved in eukaryotes, namely, the inactivation of whole chromosomes. The special case of the inactivation of the X chromosome in mammals is discussed, paying particular attention to the physical process of the spread of X inactivation in monotremes (platypus and echidna). When experimental data is unavailable some theoretical analysis is possible based on the idea that in certain cases collective phenomena in genetics, rather than chemical detail, are better correlates of complex chemical processes. (author). 65 refs

  17. The Empirical Analysis of Income and Food Consumption Structure of Urban Residents in China

    OpenAIRE

    Yanbing Cai; Xueni Liu

    2013-01-01

    Using the panel data of food income and expenditure, this study further analyzes how income influences on food consumption structure based on analysis of evolution characteristics of income and food consumption structure of urban residents in China during 2000-2010 year. In addition, the study compares the difference of food consumption structure of eastern, central and western areas in China. The results are showed as following: with the improvement of income level, the Engel’s coefficients ...

  18. 基于主成分分析法的山东半岛蓝色经济区多中心空间结构演变研究%Research on the evolution of polycentric spatial structure of Shandong Peninsula Blue Economic Zone based on principal component analysis

    Institute of Scientific and Technical Information of China (English)

    马学广; 窦鹏

    2015-01-01

    多中心城市区域是当代区域发展的主要模式,也是区域研究的重要方面。而多中心区域空间结构的研判也是制定适宜区域政策的前提,是推动多中心城市区域健康可持续发展的重要基础。利用山东半岛蓝色经济区各城市2013年、2008年、2003年的统计年鉴数据,以县(区)行政单元为基本空间单元,辅以城市行政空间单元,采用主成分分析法和聚类分析法,测算蓝色经济区最近10年的空间组织格局演变过程。研究发现,山东半岛蓝色经济区经历了从“核心-边缘”特征明显的单中心模式到“多中心”结构特征的空间结构演变过程,其空间发展的“去单核化”和“多中心性”特征较明显。%Polycentric urban region is the main model of the present regional development, and it is also an important aspect of the regional study. The judgment of regional spatial structure of multiple centers is the premise of making appropriate regional policy, and it is also an important basis for promoting the healthy and sustainable development of polycentric urban regions. By using the statistical yearbook data (the year of 2013, 2008 and 2003) of Shandong Peninsula Blue Economic Zone (SPBEZ) of each city, taking the county (district) administrative unit as the basic spatial unit and supplemented by urban administrative space unit, and adopting principal component analysis and cluster analysis to calculate the spatial structure evolution process of SPBEZ in recent 10 years. Research suggests that SPBEZ has experienced obvious spatial structure change from the core-periphery feature of single-center mode to significant development course of polycentric, which features from single core to multiple centers.

  19. Bayesian analysis of cosmic structures

    CERN Document Server

    Kitaura, Francisco-Shu

    2011-01-01

    We revise the Bayesian inference steps required to analyse the cosmological large-scale structure. Here we make special emphasis in the complications which arise due to the non-Gaussian character of the galaxy and matter distribution. In particular we investigate the advantages and limitations of the Poisson-lognormal model and discuss how to extend this work. With the lognormal prior using the Hamiltonian sampling technique and on scales of about 4 h^{-1} Mpc we find that the over-dense regions are excellent reconstructed, however, under-dense regions (void statistics) are quantitatively poorly recovered. Contrary to the maximum a posteriori (MAP) solution which was shown to over-estimate the density in the under-dense regions we obtain lower densities than in N-body simulations. This is due to the fact that the MAP solution is conservative whereas the full posterior yields samples which are consistent with the prior statistics. The lognormal prior is not able to capture the full non-linear regime at scales ...

  20. {sup 3}He retention and structural evolution in erbium tritides: Phase and aging effects

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.S., E-mail: zlxs77@163.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Thin Film Centre, Scottish Universities Physics Alliance (SUPA), University of West of Scotland, Paisley PA1 2BE, Scotland (United Kingdom); Zhang, L.; Wang, W.D.; Liu, Q. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Peng, S.M., E-mail: pengshuming@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Ding, W.; Long, X.G.; Cheng, G.J.; Liang, J.H. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Fu, Y.Q. [Thin Film Centre, Scottish Universities Physics Alliance (SUPA), University of West of Scotland, Paisley PA1 2BE, Scotland (United Kingdom)

    2015-06-15

    Highlights: • Effects of phase changes on {sup 3}He retention of Er tritide films were investigated. • The α phase in Er tritide films had no apparent effect on {sup 3}He release/retention. • Tritium content in the β phase showed significant effects on {sup 3}He retention. • Evolution of {sup 3}He in the β phase was apparently influenced by the γ phase. • Effects of phase changes on structure evolution of Er tritides were investigated. - Abstract: Effects of phase changes on {sup 3}He release/retention and crystal lattice evolution during aging of erbium (Er) tritide films were investigated using X-ray diffraction. The contents of α phase and γ phase in the Er tritide films showed significant different effects on {sup 3}He release/retention. The initial tritium stoichiometry or excess tritium atoms accommodated in the octahedral sites and the microstructure (i.e., the texture and Er{sub 2}O{sub 3} oxide inclusions) played an important role for the {sup 3}He release and the evolution of {sup 3}He bubbles in the β phase Er tritide films. In the β + γ region, evolution of {sup 3}He in the β phase was apparently influenced by the γ phase, which could result in a strongly anisotropic lattice dilation and an earlier inflection point of the expansion rate of (1 1 1) lattice parameter. A preferred occupation of {sup 3}He in basal plane of the hexagonal γ phase and the lattice expansion along the hexagonal direction were identified.

  1. Polarity Analysis of Texts using Discourse Structure

    NARCIS (Netherlands)

    Heerschop, Bas; Goosen, Frank; Hogenboom, Alexander; Frasincar, Flavius; Kaymak, Uzay; Jong, de Franciska

    2011-01-01

    Sentiment analysis has applications in many areas and the exploration of its potential has only just begun. We propose Pathos, a framework which performs document sentiment analysis (partly) based on a document’s discourse structure. We hypothesize that by splitting a text into important and less im

  2. Structural Analysis of a Tracked Vehicle Hull .

    Directory of Open Access Journals (Sweden)

    M. Mala

    1997-04-01

    Full Text Available The hull of a tracked military vehicle is complex in geometry and loading pattern. Analytical studies were carried out using numerically integrated elements for system analysis (NISA, a general finite element programme developed by the Engineering Mechanics Research Corporation (EMRC, USA. Structural changes in the initial design were made to bring deflection within acceptable limits. Dynamic stress levels for the hull structure, were determined from strain gauge measurements. The resultant stresses were obtained adding the static and dynamic values. Finite element analysis was found to be very useful to check the rigidity of the structure at design stage and to suggest suitable design stage and to suggest suitable modifications.

  3. Driving electrocatalytic activity by interface electronic structure control in a metalloprotein hybrid catalyst for efficient hydrogen evolution.

    Science.gov (United States)

    Behera, Sushant Kumar; Deb, Pritam; Ghosh, Arghya

    2016-08-17

    The rational design of metalloprotein hybrid structures and precise calculations for understanding the role of the interfacial electronic structure in regulating the HER activity of water splitting sites and their microscopic effect for obtaining robust hydrogen evolution possess great promise for developing highly efficient nano-bio hybrid HER catalysts. Here, we employ high-accuracy linear-scaling density functional theory calculations using a near-complete basis set and a minimal parameter implicit solvent model within the self-consistent calculations, on silver (Ag) ions assimilated on bacteriorhodopsin (bR) at specific binding sites. Geometry optimization indicates the formation of active sites at the interface of the metalloprotein complex and the density of states reflects the metallic nature of the active sites. The reduced value of the canonical orbital gap indicates the state of dynamic nature after Ag ion assimilation on active sites and smooth electron transfer. These incorporated active protein sites are more efficient in electrolytic splitting of water than pristine sites due to their low value of Gibbs free energy for the HER in terms of hydrogen coverages. Volcano plot analysis and the free energy diagram are compared for understanding the hydrogen evolution efficiency. Moreover, the essential role of the interfacial electronic properties in regulating the HER catalytic activity of water splitting sites and enhancing the efficiency is elucidated.

  4. Identification of Semaphorin 5A Interacting Protein by Applying Apriori Knowledge and Peptide Complementarity Related to Protein Evolution and Structure

    Institute of Scientific and Technical Information of China (English)

    Anguraj Sadanandam; Michelle L. Varney; Rakesh K. Singh

    2008-01-01

    In the post-genomic era, various computational methods that predict proteinprotein interactions at the genome level are available; however, each method has its own advantages and disadvantages, resulting in false predictions. Here we developed a unique integrated approach to identify interacting partner(s) of Semaphorin 5A (SEMA5A), beginning with seven proteins sharing similar ligand interacting residues as putative binding partners. The methods include Dwyer and Root-Bernstein/Dillon theories of protein evolution, hydropathic complementarity of protein structure, pattern of protein functions among molecules, information on domain-domain interactions, co-expression of genes and protein evolution. Among the set of seven proteins selected as putative SEMA5A interacting partners, we found the functions of Plexin B3 and Neuropilin-2 to be associated with SEMA5A.We modeled the semaphorin domain structure of Plexin B3 and found that it shares similarity with SEMA5A. Moreover, a virtual expression database search and RT-PCR analysis showed co-expression of SEMA5A and Plexin B3 and these proteins were found to have co-evolved. In addition, we confirmed the interaction of SEMA5A with Plexin B3 in co-immunoprecipitation studies. Overall, these studies demonstrate that an integrated method of prediction can be used at the genome level for discovering many unknown protein binding partners with known ligand binding domains.

  5. Driving electrocatalytic activity by interface electronic structure control in a metalloprotein hybrid catalyst for efficient hydrogen evolution.

    Science.gov (United States)

    Behera, Sushant Kumar; Deb, Pritam; Ghosh, Arghya

    2016-08-17

    The rational design of metalloprotein hybrid structures and precise calculations for understanding the role of the interfacial electronic structure in regulating the HER activity of water splitting sites and their microscopic effect for obtaining robust hydrogen evolution possess great promise for developing highly efficient nano-bio hybrid HER catalysts. Here, we employ high-accuracy linear-scaling density functional theory calculations using a near-complete basis set and a minimal parameter implicit solvent model within the self-consistent calculations, on silver (Ag) ions assimilated on bacteriorhodopsin (bR) at specific binding sites. Geometry optimization indicates the formation of active sites at the interface of the metalloprotein complex and the density of states reflects the metallic nature of the active sites. The reduced value of the canonical orbital gap indicates the state of dynamic nature after Ag ion assimilation on active sites and smooth electron transfer. These incorporated active protein sites are more efficient in electrolytic splitting of water than pristine sites due to their low value of Gibbs free energy for the HER in terms of hydrogen coverages. Volcano plot analysis and the free energy diagram are compared for understanding the hydrogen evolution efficiency. Moreover, the essential role of the interfacial electronic properties in regulating the HER catalytic activity of water splitting sites and enhancing the efficiency is elucidated. PMID:27499158

  6. Structural Analysis Of Offshore Structures Exposed To Blast Loads

    DEFF Research Database (Denmark)

    Hansen, Hans Jakup; Thygesen, Ulf; Kristensen, Anders;

    2002-01-01

    Numerical methods for simulations of blast loads and resulting structural response are investigated and compared to results obtained from tests. The CFD code EXSIM is used for the simulation of the blast load. This code provides a load profile wich is entered in the FEM analysis model....

  7. The impact of nonlinear functional responses on the long-term evolution of food web structure.

    Science.gov (United States)

    Drossel, Barbara; McKane, Alan J; Quince, Christopher

    2004-08-21

    We investigate the long-term web structure emerging in evolutionary food web models when different types of functional responses are used. We find that large and complex webs with several trophic layers arise only if the population dynamics is such that it allows predators to focus on their best prey species. This can be achieved using modified Lotka-Volterra or Holling/Beddington functional responses with effective couplings that depend on the predator's efficiency at exploiting the prey, or a ratio-dependent functional response with adaptive foraging. In contrast, if standard Lotka-Volterra or Holling/Beddington functional responses are used, long-term evolution generates webs with almost all species being basal, and with additionally many links between these species. Interestingly, in all cases studied, a large proportion of weak links result naturally from the evolution of the food webs.

  8. Structural and functional evolution of 2',3'-cyclic nucleotide 3'-phosphodiesterase.

    Science.gov (United States)

    Myllykoski, Matti; Seidel, Leonie; Muruganandam, Gopinath; Raasakka, Arne; Torda, Andrew E; Kursula, Petri

    2016-06-15

    2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) is an abundant membrane-associated enzyme within the vertebrate myelin sheath. While the physiological function of CNPase still remains to be characterized in detail, it is known - in addition to its in vitro enzymatic activity - to interact with other proteins, small molecules, and membrane surfaces. From an evolutionary point of view, it can be deduced that CNPase is not restricted to myelin-forming cells or vertebrate tissues. Its evolution has involved gene fusion, addition of other small segments with distinct functions, such as membrane attachment, and possibly loss of function at the polynucleotide kinase-like domain. Currently, it is unclear whether the enzymatic function of the conserved phosphodiesterase domain in vertebrate myelin has a physiological role, or if CNPase could actually function - like many other classical myelin proteins - in a more structural role. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26367445

  9. Structure and Evolution of Magnetic Fields Associated with Solar Eruptions (Invited Review)

    CERN Document Server

    Wang, Haimin

    2014-01-01

    This paper reviews the studies of solar photospheric magnetic field evolution in active regions and its relationship to solar flares. It is divided into two topics, the magnetic structure and evolution leading to solar eruptions and the rapid changes of photospheric magnetic field associated with eruptions. For the first topic, we describe the magnetic complexity, new flux emergence, flux cancellation, shear motions, sunspot rotation, and magnetic helicity injection, which may all contribute to the storage and buildup of energy and triggering of solar eruptions. For the second topic, we concentrate on the observations of rapid and irreversible changes of photospheric magnetic field associated with flares, and the implication on the restructuring of three-dimensional magnetic field. In particular, we emphasize the recent advances in observations of photospheric magnetic field, as state-of-the-art observing facilities (such as Hinode and Solar Dynamic Observatory) become available. The linkage between observati...

  10. Scale covariant gravitation. V - Kinetic theory. VI - Stellar structure and evolution

    Science.gov (United States)

    Hsieh, S.-H.; Canuto, V. M.

    1981-01-01

    A scale covariant kinetic theory for particles and photons is developed. The mathematical framework of the theory is given by the tangent bundle of a Weyl manifold. The Liouville equation is derived, and solutions to corresponding equilibrium distributions are presented and shown to yield thermodynamic results identical to the ones obtained previously. The scale covariant theory is then used to derive results of interest to stellar structure and evolution. A radiative transfer equation is derived that can be used to study stellar evolution with a variable gravitational constant. In addition, it is shown that the sun's absolute luminosity scales as L approximately equal to GM/kappa, where kappa is the stellar opacity. Finally, a formula is derived for the age of globular clusters as a function of the gravitational constant using a previously derived expression for the absolute luminosity.

  11. Evolution and mechanism of the periodical structures formed on Ti plate under femtosecond laser irradiation

    Science.gov (United States)

    Liu, Dong; Chen, Chuansong; Man, Baoyuan; Meng, Xue; Sun, Yanna; Li, Feifei

    2016-08-01

    This work investigates the femtosencond laser (fs-laser) induced periodical surface structures (FLIPSS) on titanium plate including the concentric rings, microgrooves and subwavelength ripples. The evolution of the three types of the structures at different laser fluence and shot number is investigated experimentally in detail. The competition mechanisms exist among the different FLIPSS. A processing window for each resulting FLIPSS is obtained. In order to give an overall understanding of the FLIPSS, the formation mechanisms of each type of FLIPSS are discussed. The formation of the ripples is well explained by the propagating of the surface plasma wave (SPW) on the air/Ti interface. The evolutions of the ripple distribution are well understood according to this model as well. It is concluded that the interaction of the scattered wave of the laser light with the surface wave is concluded to give rise to the microgroove structure. According to our observation, the shape of the concentric rings does not change with the variation of the laser fluence and pulse number. The structure could be originated from the optical interference between the transmitted and reflected laser beams by the two surfaces of the biconvex lens. This investigation could not only make a further understanding of the formations of FLIPSS but also provide the possibility to control the surface morphologies in laser processing.

  12. Pollen sensitivity to ultraviolet-B (UV-B) suggests floral structure evolution in alpine plants.

    Science.gov (United States)

    Zhang, Chan; Yang, Yong-Ping; Duan, Yuan-Wen

    2014-03-31

    Various biotic and abiotic factors are known to exert selection pressures on floral traits, but the influence of ultraviolet-B (UV-B) light on the evolution of flower structure remains relatively unexplored. We have examined the effectiveness of flower structure in blocking radiation and the effects of UV-B on pollen viability in 42 species of alpine plants in the Hengduan Mountains, China. Floral forms were categorized as either protecting or exposing pollen grains to UV-B. The floral materials of plants with exposed and protected pollen grains were able to block UV-B at similar levels. Exposure to UV-B radiation in vitro resulted in a significantly greater loss of viability in pollen from plant species with protective floral structures. The pronounced sensitivity of protected pollen to UV-B radiation was associated with the type of flower structure. These findings demonstrate that UV-B plays an important role in the evolution of protective floral forms in alpine plants.

  13. Geostatistical investigation into the temporal evolution of spatial structure in a shallow water table

    Directory of Open Access Journals (Sweden)

    S. W. Lyon

    2006-01-01

    during many rain events. During the summer, when evaporation exceeds precipitation, the ranges of the indicator semivariograms decreased during rainfall events due to isolated responses in the water table. For the longer, monthly time interval, semivariograms exhibited higher sills and shorter ranges during spring and lower sills and longer ranges during the summer. For this long time interval, there was a good correlation between probability of exceeding the time-variable median water table and the soil topographical wetness index during the spring. Indicator kriging incorporating both the short and long time interval structure of the shallow water table (hard and soft data, respectively provided more realistic maps that agreed better with actual observations than the hard data alone. This technique to represent both event-based and seasonal trends incorporates the hillslope-scale hydrological processes to capture significant patterns in the shallow water table. Geostatistical analysis of the spatial and temporal evolution of the shallow water table gives information about the formation of saturated areas important in the understanding hydrological processes working at this and other hillslopes.

  14. Genetic analysis of wheat domestication and evolution under domestication.

    Science.gov (United States)

    Peleg, Zvi; Fahima, Tzion; Korol, Abraham B; Abbo, Shahal; Saranga, Yehoshua

    2011-10-01

    Wheat is undoubtedly one of the world's major food sources since the dawn of Near Eastern agriculture and up to the present day. Morphological, physiological, and genetic modifications involved in domestication and subsequent evolution under domestication were investigated in a tetraploid recombinant inbred line population, derived from a cross between durum wheat and its immediate progenitor wild emmer wheat. Experimental data were used to test previous assumptions regarding a protracted domestication process. The brittle rachis (Br) spike, thought to be a primary characteristic of domestication, was mapped to chromosome 2A as a single gene, suggesting, in light of previously reported Br loci (homoeologous group 3), a complex genetic model involved in spike brittleness. Twenty-seven quantitative trait loci (QTLs) conferring threshability and yield components (kernel size and number of kernels per spike) were mapped. The large number of QTLs detected in this and other studies suggests that following domestication, wheat evolutionary processes involved many genomic changes. The Br gene did not show either genetic (co-localization with QTLs) or phenotypic association with threshability or yield components, suggesting independence of the respective loci. It is argued here that changes in spike threshability and agronomic traits (e.g. yield and its components) are the outcome of plant evolution under domestication, rather than the result of a protracted domestication process. Revealing the genomic basis of wheat domestication and evolution under domestication, and clarifying their inter-relationships, will improve our understanding of wheat biology and contribute to further crop improvement.

  15. Analysis of Haptics Evolution from Web Search Engines’ Data

    Directory of Open Access Journals (Sweden)

    Agnès Guerraz

    2009-08-01

    Full Text Available This article proposes using search engine results data such as the number of results containing relevant terms, to measure the evolution of Haptics, the field devoted to the science and technology of the sense of touch. Haptics is a complex discipline which is at the intersection of the knowledge of several specialized fields like robotics, computer science, psychology, and mathematics. It can also appear as a new and emergent discipline due to the fact that many promising haptic interfaces, which allow innovative multimodal applications in many fields, have become mature only recently. The study presented in this article uses data collected at different periods of time (in December 1999, January 2004, January 2005, November 2006 and April 2007 onWeb search engines from requests on three different terminologies: haptique, haptik and haptics, taken respectively from French, German, and English languages. The evolution of Haptics is seemingly reflected by to the online frequency of these specific terms over time. This evolution has been measured by considering the Internet community through search engines such as Google or Yahoo!

  16. Structural-Thermal-Optical-Performance (STOP) Analysis

    Science.gov (United States)

    Bolognese, Jeffrey; Irish, Sandra

    2015-01-01

    The presentation will be given at the 26th Annual Thermal Fluids Analysis Workshop (TFAWS 2015) hosted by the Goddard Spaceflight Center (GSFC) Thermal Engineering Branch (Code 545). A STOP analysis is a multidiscipline analysis, consisting of Structural, Thermal and Optical Performance Analyses, that is performed for all space flight instruments and satellites. This course will explain the different parts of performing this analysis. The student will learn how to effectively interact with each discipline in order to accurately obtain the system analysis results.

  17. Magnetic Structure of Continental Crust:Implications for Crustal Structure and Evolution

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Magnetic structure of the continental crust is one of the important geophysical aspects of continental lithosphere. This paper reviews the achievements in the research into the magnetic structure and its significance for crustal tectonics, composition, metamorphic facies, crust-mantle interaction and magnetization of deep crust. Further studies are suggested according to the basic principles of rock and mineral magnetism in terms of petrology, geochemistry and structural geol ogy. Emphasis is placed on new geological ideas and synthetic studies of the relationship between deep geological processes and interpretation of gravity, magnetic, electrical and seismic data. The relationships between magnetic, density, electricity, velocity, geothermal structures and deep geodynamic processes are taken as a system for the research into the deep geology.

  18. Evolution of phase segregation and eutectic structures in AgPb18SbTe20

    International Nuclear Information System (INIS)

    The evolution of phase segregation in stoichiometric quenched AgPbmSbTe2+m (m = 18, Lead-Antimony-Silver-Tellurium - LAST-18) compounds was studied starting from the known pseudo-binary diagrams among Ag2Te, PbTe, Sb2Te3 and AgSbTe2. The compositions of secondary phases indicate that liquid phase during cooling, even under quenching conditions, follows mainly the liquidus line on the 2PbTe-Ag0.45Sb0.55Te1.05 quasi-binary section of the phase diagram until it reaches a critical point (18 mol.% of 2PbTe) and then turns to Ag2Te- and Sb2Te3-rich sides of quasi-ternary system. This has led to the formation of various secondary phases at various stages during the solidification, whose microstructural features and morphology strongly depend upon their chemical composition. Moreover, during solidification the local compositional fluctuations of liquid phase in combination with the shift of liquid composition towards Sb-rich side of the phase diagram resulted in the development of eutectic microstructures in some regions of LAST-18 matrix phase. This suggests there exists a miscibility gap and eutectic point below 600 C on the 2PbTe-Ag0.45Sb0.55Te1.05 boundary line. These eutectic lamellar structures with a cumulative composition close to LAST-3 are on the 200-500 nm length scales and possess thermal conductivity of 0.55-0.65 W/m K at room temperature. The low thermal conductivity of lamellar eutectic structures was later confirmed on bulk samples using laser flash analysis, where the samples were synthesized by quenching and annealing. The results clearly demonstrate that one can engineer the microstructures in LAST compounds by selecting the appropriate initial composition from quasi PbTe-Ag2Te-Sb2Te3 ternary phase diagram to lower the thermal conductivity further. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. SPATIAL STRUCTURE EVOLUTION OF SYSTEM OF RECREATION BUSINESS DISTRICT--A Case of Suzhou City

    Institute of Scientific and Technical Information of China (English)

    LI Li-mei; TAO Wei

    2003-01-01

    The growing attention on urban tourism was very widespread. There are two angles to study urban tourism: supply-side and demand-side. And the supply-side of the tourism remains very important. The RBD (Recreation Business District) is a useful framework to understand the components of urban tourism and how they fit together. The paper begins with a review on the RBD and the spatial structure of tourism in urban areas and then attempts to develop a more general understanding of the spatial structure evolution of RBDs in a tourist-historic citySuzhou. The spatial structures and functions of the RBDs in Suzhou are examined, based on field observations, interviews with city officials and industry leaders, and a review of available documents. The urban tourism of Suzhou has developed in a range of contexts, that various types of RBDs have emerged as a result of different urban development strategies. The spatial structure has evolved from the past "Single-cored Structure" to "Double-cored Structure"at present, and then to "Chain Structure" in the future. The spatial form and evolution of RBD in Suzhou are closely relative with its urban spatial expansion. Urban area dispersal is the prerequisite of the emergence of the RBD. Planning and constructing the RBD becomes a new impetus to urban growth or renewal. Finally, a number of strategies for planning and developing the RBD in Suzhou are suggested. The different RBDs should adopt different strategies.Intensification can be the possible strategy for the RBDs in the ancient city. Accreting with the urban theme park or engrafting on the Jinji Lake is suggested respectively for the RBD in the Suzhou New District and the Suzhou Industrial Park.

  20. A theoretical model for the evolution of two-dimensional large-scale coherent structures in a mixing layer

    Institute of Scientific and Technical Information of China (English)

    周恒; 马良

    1995-01-01

    By a proper combination of the modified weakly nonlinear theory of hydrodynamic stability and the energy method, the spatial evolution of the large-scale coherent structures in a mixing layer has been calculated. The results are satisfactory.

  1. Kinematic Analysis of a Hybrid Structure

    Directory of Open Access Journals (Sweden)

    Duan Q.J.

    2012-11-01

    Full Text Available This paper presents a kinematic analysis and simulation of a hybrid structure applied to the new design cable‐suspended feed structure (CSFS for the next generation of large spherical radio telescopes. First, considering the requirement that feeds should be tilted from 40° to 60° and that the tracking precision in steady state is 4mm, a novel design of the feed supporting structure including a cable‐cabin structure, an AB axis structure and a Stewart platform is performed. Next, kinematic analysis and the simulation of the CSFS are done. Simulations have been developed in combination with the 50m CSFS model, which demonstrate the effectiveness and feasibility of the proposed three‐level cable‐suspended feed system.

  2. Probabilistic structural analysis computer code (NESSUS)

    Science.gov (United States)

    Shiao, Michael C.

    1988-01-01

    Probabilistic structural analysis has been developed to analyze the effects of fluctuating loads, variable material properties, and uncertain analytical models especially for high performance structures such as SSME turbopump blades. The computer code NESSUS (Numerical Evaluation of Stochastic Structure Under Stress) was developed to serve as a primary computation tool for the characterization of the probabilistic structural response due to the stochastic environments by statistical description. The code consists of three major modules NESSUS/PRE, NESSUS/FEM, and NESSUS/FPI. NESSUS/PRE is a preprocessor which decomposes the spatially correlated random variables into a set of uncorrelated random variables using a modal analysis method. NESSUS/FEM is a finite element module which provides structural sensitivities to all the random variables considered. NESSUS/FPI is Fast Probability Integration method by which a cumulative distribution function or a probability density function is calculated.

  3. FEM structural analysis of ITER gravity supports

    International Nuclear Information System (INIS)

    Because of the complexity of the load cases, the gravity support of ITER endures several large forces during operation besides the dead weight of the magnet system, such as electromagnetic force on the magnets, thermal load and seismic loads (SL). In order to verify the reliability of the design, and make the gravity support operate safely under the various load cases, it is very important to analyze the applied force on the gravity support in different load cases. In this paper, finite-element-method (FEM) is used for the structural analysis. 3-D FEM models of the overall gravity support system, with 20 degree sector and 360 degree respectively, are created by ANSYS according to different load cases. The 20 degree model in the torus is used for the structural analysis of the gravity support system under the several symmetric load combinations, and the 360 degree model is used for the structural analysis under the load combinations with the asymmetric SL. The analysis results are given, such as the static structural analysis and the buckling analysis for the different load combinations, and the modal analysis for the natural frequencies. The calculation results reveal that all of the gravity support components have enough safety margins against various load combinations. (authors)

  4. Recent Advances on the Understanding of Structural and Composition Evolution of LMR Cathodes for Li-ion Batteries

    OpenAIRE

    Yan, Pengfei; Zheng, Jianming; Xiao, Jie; Wang, Chong-Min; Zhang, Ji-Guang

    2015-01-01

    Lithium-and-manganese-rich (LMR) cathode materials have been regarded as very promising for lithium (Li)-ion battery applications. However, their practical application is still limited by several barriers such as their limited electrochemical stability and rate capability. In this work, we present recent progress on the understanding of structural and compositional evolution of LMR cathode materials, with an emphasis being placed on the correlation between structural/chemical evolution and el...

  5. A global gene evolution analysis on Vibrionaceae family using phylogenetic profile

    Directory of Open Access Journals (Sweden)

    Vitulo Nicola

    2007-03-01

    Full Text Available Abstract Background Vibrionaceae represent a significant portion of the cultivable heterotrophic sea bacteria; they strongly affect nutrient cycling and some species are devastating pathogens. In this work we propose an improved phylogenetic profile analysis on 14 Vibrionaceae genomes, to study the evolution of this family on the basis of gene content. The phylogenetic profile is based on the observation that genes involved in the same process (e.g. metabolic pathway or structural complex tend to be concurrently present or absent within different genomes. This allows the prediction of hypothetical functions on the basis of a shared phylogenetic profiles. Moreover this approach is useful to identify putative laterally transferred elements on the basis of their presence on distantly phylogenetically related bacteria. Results Vibrionaceae ORFs were aligned against all the available bacterial proteomes. Phylogenetic profile is defined as an array of distances, based on aminoacid substitution matrixes, from single genes to all their orthologues. Final phylogenetic profiles, derived from non-redundant list of all ORFs, was defined as the median of all the profiles belonging to the cluster. The resulting phylogenetic profiles matrix contains gene clusters on the rows and organisms on the columns. Cluster analysis identified groups of "core genes" with a widespread high similarity across all the organisms and several clusters that contain genes homologous only to a limited set of organisms. On each of these clusters, COG class enrichment has been calculated. The analysis reveals that clusters of core genes have the highest number of enriched classes, while the others are enriched just for few of them like DNA replication, recombination and repair. Conclusion We found that mobile elements have heterogeneous profiles not only across the entire set of organisms, but also within Vibrionaceae; this confirms their great influence on bacteria evolution even

  6. Highly efficient light-trapping structure design inspired by natural evolution.

    Science.gov (United States)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-01-01

    Recent advances in nanophotonic light trapping open up the new gateway to enhance the absorption of solar energy beyond the so called Yablonovitch Limit. It addresses the urgent needs in developing low cost thin-film solar photovoltaic technologies. However, current design strategy mainly relies on the parametric approach that is subject to the predefined topological design concepts based on physical intuition. Incapable of dealing with the topological variation severely constrains the design of optimal light trapping structure. Inspired by natural evolution process, here we report a design framework driven by topology optimization based on genetic algorithms to achieve a highly efficient light trapping structure. It has been demonstrated that the optimal light trapping structures obtained in this study exhibit more than 3-fold increase over the Yablonovitch Limit with the broadband absorption efficiency of 48.1%, beyond the reach of intuitive designs.

  7. Structural evolution and strength change of a metallic glass at different temperatures

    Science.gov (United States)

    Tong, X.; Wang, G.; Stachurski, Z. H.; Bednarčík, J.; Mattern, N.; Zhai, Q. J.; Eckert, J.

    2016-08-01

    The structural evolution of a Zr64.13Cu15.75Ni10.12Al10 metallic glass is investigated in-situ by high-energy synchrotron X-ray radiation upon heating up to crystallization. The structural rearrangements on the atomic scale during the heating process are analysed as a function of temperature, focusing on shift of the peaks of the structure factor in reciprocal space and the pair distribution function and radial distribution function in real space which are correlated with atomic rearrangements and progressing nanocrystallization. Thermal expansion and contraction of the coordination shells is measured and correlated with the bulk coefficient of thermal expansion. The characteristics of the microstructure and the yield strength of the metallic glass at high temperature are discussed aiming to elucidate the correlation between the atomic arrangement and the mechanical properties.

  8. Structural evolution and strength change of a metallic glass at different temperatures.

    Science.gov (United States)

    Tong, X; Wang, G; Stachurski, Z H; Bednarčík, J; Mattern, N; Zhai, Q J; Eckert, J

    2016-01-01

    The structural evolution of a Zr64.13Cu15.75Ni10.12Al10 metallic glass is investigated in-situ by high-energy synchrotron X-ray radiation upon heating up to crystallization. The structural rearrangements on the atomic scale during the heating process are analysed as a function of temperature, focusing on shift of the peaks of the structure factor in reciprocal space and the pair distribution function and radial distribution function in real space which are correlated with atomic rearrangements and progressing nanocrystallization. Thermal expansion and contraction of the coordination shells is measured and correlated with the bulk coefficient of thermal expansion. The characteristics of the microstructure and the yield strength of the metallic glass at high temperature are discussed aiming to elucidate the correlation between the atomic arrangement and the mechanical properties. PMID:27484873

  9. ON THE EVOLUTION OF LARGE SCALE STRUCTURES IN THREE-DIMENSIONAL MIXING LAYERS

    Institute of Scientific and Technical Information of China (English)

    罗纪生; H.E, Fiedler

    2001-01-01

    In this paper, several mathematical models for the large scale structures in some special kinds of mixing layers, which might be practically useful for enhancing the mixing, are proposed. First, the linear growth rate of the large scale structures in the mixing layers was calculated. Then, using the much improved weakly non-linear theory, combined with the energy method, the non-linear evolution of large scale structures in two special mixing layer configurations is calculated. One of the mixing layers has equal magnitudes of the upstream velocity vectors, while the angles between the velocity vectors and the trailing edge were π/2 - and π/2 + ,respectively. The other mixing layer was generated by a splitter-plate with a 45-degree-sweep trailing edge.

  10. Structural evolution of fault zones in sandstone by multiple deformation mechanisms: Moab fault, southeast Utah

    Science.gov (United States)

    Davatzes, N.C.; Eichhubl, P.; Aydin, A.

    2005-01-01

    Faults in sandstone are frequently composed of two classes of structures: (1) deformation bands and (2) joints and sheared joints. Whereas the former structures are associated with cataclastic deformation, the latter ones represent brittle fracturing, fragmentation, and brecciation. We investigated the distribution of these structures, their formation, and the underlying mechanical controls for their occurrence along the Moab normal fault in southeastern Utah through the use of structural mapping and numerical elastic boundary element modeling. We found that deformation bands occur everywhere along the fault, but with increased density in contractional relays. Joints and sheared joints only occur at intersections and extensional relays. In all locations , joints consistently overprint deformation bands. Localization of joints and sheared joints in extensional relays suggests that their distribution is controlled by local variations in stress state that are due to mechanical interaction between the fault segments. This interpretation is consistent with elastic boundary element models that predict a local reduction in mean stress and least compressive principal stress at intersections and extensional relays. The transition from deformation band to joint formation along these sections of the fault system likely resulted from the combined effects of changes in remote tectonic loading, burial depth, fluid pressure, and rock properties. In the case of the Moab fault, we conclude that the structural heterogeneity in the fault zone is systematically related to the geometric evolution of the fault, the local state of stress associated with fault slip , and the remote loading history. Because the type and distribution of structures affect fault permeability and strength, our results predict systematic variations in these parameters with fault evolution. ?? 2004 Geological Society of America.

  11. Analysis of microstructural evolution driven by production bias

    DEFF Research Database (Denmark)

    Woo, C.H.; Semenov, A.A.; Singh, B.N.

    1993-01-01

    The concept of production bias was first considered in the preceding workshop in this series at Silkeborg in 1989. Since then, much work has been done to investigate the validity of the concept, and its usefulness in complementing the current theory of microstructure evolution based solely...... on the sink bias (e.g., dislocation bias) as a driving force. Comparison of the theory with experimental results clearly supports the concept. The present paper reviews and summarizes these investigations, and arrives at the following conclusions: a) the concept of production bias is consistent...

  12. Evolution of self-organization in nano-structured PVD coatings under extreme tribological conditions

    International Nuclear Information System (INIS)

    Highlights: • The evolution of self-organization under extreme frictional conditions has been studied. • Comprehensive characterization of the tribo-films was made using various surface analytical techniques. • During the running-in stage, mullite tribo-ceramics predominate on the surface of the nano-multilayer coating, establishing a functional hierarchy within the layer of tribo-films. • It is possible to control tribo-film evolution during self-organization by means of an increase in structural complexity and the non-equilibrium state of the surface engineered layer. - Abstract: The evolution of the self-organization process where dissipative structures are formed under the extreme frictional conditions associated with high performance dry machining of hardened steels has been studied in detail. The emphasis was on the progressive studies of surface transformations within multilayer and monolayer TiAlCrSiYN-based PVD coatings during the running-in stage of wear when self-organization process occurs. The coating layer was characterized by high resolution electron energy-loss spectroscopy (HREELS). It is shown that the nano-multilayer coating possesses higher non-equilibrium structure in comparison to the monolayer. Comprehensive studies of the tribo-films (dissipative structures) formed on the friction surface were made using a number of advanced surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The data obtained for the tribo-films was combined with the detailed TEM studies of the structural and phase transformations within the underlying coating layer. This data was related to the micro-mechanical characteristics of the coating layer and its wear resistance. It was demonstrated that the evolution of the self-organization process is strongly controlled by the characteristics of the tribo-films formed at different stages of the wear process. Within running-in stage (after

  13. Evolution of self-organization in nano-structured PVD coatings under extreme tribological conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fox-Rabinovich, G., E-mail: gfox@mcmaster.ca [Department of Mechanical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON, Canada L8S 4L7 (Canada); Kovalev, A. [Surface Phenomena Researches Group, CNIICHERMET, 9/23, 2-nd Baumanskaya Street, Moscow 105005 (Russian Federation); Aguirre, M.H. [Laboratory of Advanced Microscopy, Institute of Nanoscience of Aragón, University of Zaragoza, 50018 Zaragoza (Spain); Yamamoto, K. [Materials Research Laboratory, Kobe Steel Ltd, 1-5-5 Takatsuda-dai, Nishi-ku, Kobe 651-2271, Hyogo (Japan); Veldhuis, S. [Department of Mechanical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON, Canada L8S 4L7 (Canada); Gershman, I. [All-Russian Railway Research Institute, 10 Third Mytishchinskaya Street, Moscow 29851 (Russian Federation); Rashkovskiy, A. [Surface Phenomena Researches Group, CNIICHERMET, 9/23, 2-nd Baumanskaya Street, Moscow 105005 (Russian Federation); Endrino, J.L. [Albengoa Research, Energia Solar 1, Palmas Altas, Seville 41014 (Spain); Beake, B. [Micro Materials Limited, Willow House, Yale Business Village, Ellice Way, Wrexham LL13 7YL (United Kingdom); Dosbaeva, G. [Department of Mechanical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON, Canada L8S 4L7 (Canada); Wainstein, D. [Surface Phenomena Researches Group, CNIICHERMET, 9/23, 2-nd Baumanskaya Street, Moscow 105005 (Russian Federation); Yuan, Junifeng; Bunting, J.W. [Department of Mechanical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON, Canada L8S 4L7 (Canada)

    2014-04-01

    Highlights: • The evolution of self-organization under extreme frictional conditions has been studied. • Comprehensive characterization of the tribo-films was made using various surface analytical techniques. • During the running-in stage, mullite tribo-ceramics predominate on the surface of the nano-multilayer coating, establishing a functional hierarchy within the layer of tribo-films. • It is possible to control tribo-film evolution during self-organization by means of an increase in structural complexity and the non-equilibrium state of the surface engineered layer. - Abstract: The evolution of the self-organization process where dissipative structures are formed under the extreme frictional conditions associated with high performance dry machining of hardened steels has been studied in detail. The emphasis was on the progressive studies of surface transformations within multilayer and monolayer TiAlCrSiYN-based PVD coatings during the running-in stage of wear when self-organization process occurs. The coating layer was characterized by high resolution electron energy-loss spectroscopy (HREELS). It is shown that the nano-multilayer coating possesses higher non-equilibrium structure in comparison to the monolayer. Comprehensive studies of the tribo-films (dissipative structures) formed on the friction surface were made using a number of advanced surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The data obtained for the tribo-films was combined with the detailed TEM studies of the structural and phase transformations within the underlying coating layer. This data was related to the micro-mechanical characteristics of the coating layer and its wear resistance. It was demonstrated that the evolution of the self-organization process is strongly controlled by the characteristics of the tribo-films formed at different stages of the wear process. Within running-in stage (after

  14. Structural evolution of epitaxial SrCoOx films near topotactic phase transition

    International Nuclear Information System (INIS)

    Control of oxygen stoichiometry in complex oxides via topotactic phase transition is an interesting avenue to not only modifying the physical properties, but utilizing in many energy technologies, such as energy storage and catalysts. However, detailed structural evolution in the close proximity of the topotactic phase transition in multivalent oxides has not been much studied. In this work, we used strontium cobaltites (SrCoOx) epitaxially grown by pulsed laser epitaxy (PLE) as a model system to study the oxidation-driven evolution of the structure, electronic, and magnetic properties. We grew coherently strained SrCoO2.5 thin films and performed post-annealing at various temperatures for topotactic conversion into the perovskite phase (SrCoO3-δ). We clearly observed significant changes in electronic transport, magnetism, and microstructure near the critical temperature for the topotactic transformation from the brownmillerite to the perovskite phase. Nevertheless, the overall crystallinity was well maintained without much structural degradation, indicating that topotactic phase control can be a useful tool to control the physical properties repeatedly via redox reactions

  15. INTERNAL STRUCTURE OF FAULT ZONES: SPATIAL AND TEMPORAL EVOLUTION STUDIES ON CLAY MODELS

    Directory of Open Access Journals (Sweden)

    Konstantin Zh Seminsky

    2015-09-01

    Full Text Available Based on results obtained from experiments on clay models, it appeared possible to establish main regularities in the evolution of normal and strike-slip zones which structures are formed heterogeneously in time and space. The spatial heterogeneity is reflected in the regular pattern of the fault zone structure due to the fact that sectors of two different types are length-wisely alternating in the fault zone. Within sectors of Type 1, the main fault forms rapidly. Sectors of Type 2 are characterized by the long-term evolution of the pattern, significant width and high densities of fractures; in final development phases, they are represented by relay structures. The temporal heterogeneity is manifested by stages and sub-stages in the development of the fracture network, which are closely interrelated. Each of the three main stages is associated with specific deformational behaviour of the medium and a particular type of the fracture pattern, as suggested by results of our tectonophysical modelling of fracturing. The model is presented in the article; it is supported by data on natural normal and strikeslip faults.

  16. The molecular clock of neutral evolution can be accelerated or slowed by asymmetric spatial structure.

    Directory of Open Access Journals (Sweden)

    Benjamin Allen

    2015-02-01

    Full Text Available Over time, a population acquires neutral genetic substitutions as a consequence of random drift. A famous result in population genetics asserts that the rate, K, at which these substitutions accumulate in the population coincides with the mutation rate, u, at which they arise in individuals: K = u. This identity enables genetic sequence data to be used as a "molecular clock" to estimate the timing of evolutionary events. While the molecular clock is known to be perturbed by selection, it is thought that K = u holds very generally for neutral evolution. Here we show that asymmetric spatial population structure can alter the molecular clock rate for neutral mutations, leading to either Ku. Our results apply to a general class of haploid, asexually reproducing, spatially structured populations. Deviations from K = u occur because mutations arise unequally at different sites and have different probabilities of fixation depending on where they arise. If birth rates are uniform across sites, then K ≤ u. In general, K can take any value between 0 and Nu. Our model can be applied to a variety of population structures. In one example, we investigate the accumulation of genetic mutations in the small intestine. In another application, we analyze over 900 Twitter networks to study the effect of network topology on the fixation of neutral innovations in social evolution.

  17. The molecular clock of neutral evolution can be accelerated or slowed by asymmetric spatial structure.

    Science.gov (United States)

    Allen, Benjamin; Sample, Christine; Dementieva, Yulia; Medeiros, Ruben C; Paoletti, Christopher; Nowak, Martin A

    2015-02-01

    Over time, a population acquires neutral genetic substitutions as a consequence of random drift. A famous result in population genetics asserts that the rate, K, at which these substitutions accumulate in the population coincides with the mutation rate, u, at which they arise in individuals: K = u. This identity enables genetic sequence data to be used as a "molecular clock" to estimate the timing of evolutionary events. While the molecular clock is known to be perturbed by selection, it is thought that K = u holds very generally for neutral evolution. Here we show that asymmetric spatial population structure can alter the molecular clock rate for neutral mutations, leading to either Ku. Our results apply to a general class of haploid, asexually reproducing, spatially structured populations. Deviations from K = u occur because mutations arise unequally at different sites and have different probabilities of fixation depending on where they arise. If birth rates are uniform across sites, then K ≤ u. In general, K can take any value between 0 and Nu. Our model can be applied to a variety of population structures. In one example, we investigate the accumulation of genetic mutations in the small intestine. In another application, we analyze over 900 Twitter networks to study the effect of network topology on the fixation of neutral innovations in social evolution.

  18. Investigation of thermal evolution of nanodomain structures in nonlinear barium sodium niobate crystals

    Institute of Scientific and Technical Information of China (English)

    S.V.Ivanova

    2008-01-01

    By the 90°elastic light scattering investigation and far field observation in the range of 20-800℃,the relation between behavior of light scattering anomalies and evolution of nanodomain structures in lattice of barium sodium niobate(Ba2NaNb5O15,BSN)crystal was clarified.The correlation between anomalies on the temperature curves of the elastic light scattering intensity and temperature transformations of nanodomains was studied by X-ray and electron microscope methods.Phase transition near 500℃ and movement in field of scattering light could be explained by appearance of a new incommensurate phase.

  19. Evolution of the fine-structure constant in runaway dilaton models

    CERN Document Server

    Martins, C J A P; Martinelli, M; Calabrese, E; Pandolfi, S

    2015-01-01

    We study the detailed evolution of the fine-structure constant $\\alpha$ in the string-inspired runaway dilaton class of models of Damour, Piazza and Veneziano. We provide constraints on this scenario using the most recent $\\alpha$ measurements and discuss ways to distinguish it from alternative models for varying $\\alpha$. For model parameters which saturate bounds from current observations, the redshift drift signal can differ considerably from that of the canonical $\\Lambda$CDM paradigm at high redshifts. Measurements of this signal by the forthcoming European Extremely Large Telescope (E-ELT), together with more sensitive $\\alpha$ measurements, will thus dramatically constrain these scenarios.

  20. The Structure and Evolution of Protoplanetary Disks: an infrared and submillimeter view

    CERN Document Server

    Cieza, Lucas A

    2015-01-01

    Circumstellar disks are the sites of planet formation, and the very high incidence of extrasolar planets implies that most of them actually form planetary systems. Studying the structure and evolution of protoplanetary disks can thus place important constraints on the conditions, timescales, and mechanisms associated with the planet formation process. In this review, we discuss observational results from infrared and submillimeter wavelength studies. We review disk lifetimes, transition objects, disk demographics, and highlight a few remarkable results from ALMA Early Science observations. We finish with a brief discussion of ALMA's potential to transform the field in near future.

  1. Evolution of the fine-structure constant in runaway dilaton models

    Directory of Open Access Journals (Sweden)

    C.J.A.P. Martins

    2015-04-01

    Full Text Available We study the detailed evolution of the fine-structure constant α in the string-inspired runaway dilaton class of models of Damour, Piazza and Veneziano. We provide constraints on this scenario using the most recent α measurements and discuss ways to distinguish it from alternative models for varying α. For model parameters which saturate bounds from current observations, the redshift drift signal can differ considerably from that of the canonical ΛCDM paradigm at high redshifts. Measurements of this signal by the forthcoming European Extremely Large Telescope (E-ELT, together with more sensitive α measurements, will thus dramatically constrain these scenarios.

  2. Physical Properties and Evolution of Gravitationally Bound Halo Structures in Cosmological Dark Matter Simulations

    Science.gov (United States)

    Lin, David; Rocha, Miguel E.; Primack, Joel R.

    2015-01-01

    Dark matter halos existing around visible galaxies are important for studies of galaxy formation and evolution. Since dark matter does not interact with light and cannot be observed directly, studies of dark matter halos are advanced by computer simulations. Normally, halos are defined by their virialized regions; however, regions that are non-virialized can still be gravitationally bound, like the collision-bound Milky Way and Andromeda galaxies. Our project is the first comprehensive characterization of gravitationally bound halo structures, their properties, and their evolution. This study found the bound regions surrounding every dark matter halo from a 100 Mpc cube of the Bolshoi Simulation at redshifts 0, 1, and 2. We optimized computation by removing subhalos, implementing a search radius, and parallelizing code across 160 supercomputer cores. Then, we created a mass function, circular velocity function, and correlation function to describe these regions. The evolution of these properties was consistent with predictions from a ΛCDM universe model. We characterized the sizes and shapes of these bound regions across different mass intervals and redshifts. Most bound regions are elongated, although they become more spheroidal with time. The results enable astronomers to predict how dark matter halos behave in non-virialized regions of space and deepen our understanding of galaxy formation.

  3. Influence of diffusive transport on the structural evolution of W/O/W emulsions.

    Science.gov (United States)

    Sameh, Herzi; Wafa, Essafi; Sihem, Bellagha; Fernando, Leal-Calderon

    2012-12-21

    Double emulsions of the W/O/W type are compartmented materials suitable for encapsulation and sustained release of hydrophilic compounds. Initially, the inner aqueous droplets contain an encapsulated compound (EC), and the external phase comprises an osmotic regulator (OR). Over time, water and the solutes dissolved in it tend to be transferred from one aqueous compartment to the other across the oil phase. Water transfer being by far the fastest process, osmotic equilibration of two compartments is permanently ensured. Since the transport of the EC and OR generally occurs at dissimilar rates, the osmotic regulation process provokes a continuous flux of water that modifies the inner and outer volumes. We fabricated W/O/W emulsions stabilized by a couple of amphiphilic polymers, and we measured the inward and outward diffusion kinetics of the solutes. The phenomenology was explored by varying the chemical nature of the OR while keeping the same EC or vice versa. Microscope observations revealed different evolution scenarios, depending on the relative rates of transfer of the EC and OR. Structural evolution was mainly determined by the permeation ratio between the EC and the OR, irrespective of their chemical nature. In particular, a regime leading to droplet emptying was identified. In all cases, evolution was due to diffusion/permeation phenomena and coalescence was marginal. Results were discussed within the frame of a simple mean-field model taking into account the diffusive transfer of the solutes. PMID:23176152

  4. Plausible mechanisms for brain structural and size changes in human evolution.

    Science.gov (United States)

    Blazek, Vladimir; Brùzek, Jaroslav; Casanova, Manuel F

    2011-09-01

    Encephalization has many contexts and implications. On one hand, it is concerned with the transformation of eating habits, social relationships and communication, cognitive skills and the mind. Along with the increase in brain size on the other hand, encephalization is connected with the creation of more complex brain structures, namely in the cerebral cortex. It is imperative to inquire into the mechanisms which are linked with brain growth and to find out which of these mechanisms allow it and determine it. There exist a number of theories for understanding human brain evolution which originate from neurological sciences. These theories are the concept of radial units, minicolumns, mirror neurons, and neurocognitive networks. Over the course of evolution, it is evident that a whole range of changes have taken place in regards to heredity. These changes include new mutations of genes in the microcephalin complex, gene duplications, gene co-expression, and genomic imprinting. This complex study of the growth and reorganization of the brain and the functioning of hereditary factors and their external influences creates an opportunity to consider the implications of cultural evolution and cognitive faculties.

  5. The evolution of sheep production in Rio Grande do Sul and Uruguay: a comparative analysis of structural change Evolução da produção ovina no Rio Grande do Sul e Uruguai: análise comparativa de mudança estrutural

    Directory of Open Access Journals (Sweden)

    João Garibaldi Almeida Viana

    2013-06-01

    Full Text Available This study intended to analyze comparatively the evolution and the structural changes in sheep production in Rio Grande do Sul and Uruguay, being the international wool crisis used as a reference point. The analysis method was based on an econometrics time series, and the analysis began with the estimation of models that used linear and semi logarithmic regression. The estimation of the models proved that there were structural changes in sheep production in these regions, and this estimation used the wool crisis as a point of reference. In Rio Grande do Sul after 1990, the variables of sheep stock, wool and sheep meat presented a negative variable in their posted annual growth rates, as they decreased by 5.9%, 5.6% and 5.6%, respectively. The negative growth rates in Uruguay for the same variables in the same period were 6.1%, 5.6% and 0.9%, respectively. The data models indicate that there was no return to a balanced situation after the changes caused by the crisis. Therefore, the sheep market was permanently affected, which dynamically determined the evolution of sheep production and was defined by changes and uncertainty.O artigo teve por objetivo analisar comparativamente a evolução e a mudança estrutural da produção ovina no Rio Grande do Sul e Uruguai utilizando como ponto de referência a crise internacional de lã. O método de análise baseou-se na econometria de séries temporais, partindo da estimação de modelos de regressão linear e semilogarítmica. A estimação dos modelos comprovou a mudança estrutural na produção ovina do Rio Grande do Sul e Uruguai, tendo como referência a crise da lã. No Rio Grande do Sul, as variáveis de rebanho ovino, produção de lã e de carne ovina apresentou uma variação negativa em sua taxa anual pós-1990 de 5,9%, 5,6% e 5,6%, respectivamente. No Uruguai, as taxas negativas foram de 6,1%, 5,6% e 0,9%, para as mesmas variáveis do período. Os dados dos modelos indicam que não houve

  6. Telomerase and telomere-associated proteins: structural insights into mechanism and evolution.

    Science.gov (United States)

    Lewis, Karen A; Wuttke, Deborah S

    2012-01-11

    Recent advances in our structural understanding of telomerase and telomere-associated proteins have contributed significantly to elucidating the molecular mechanisms of telomere maintenance. The structures of telomerase TERT domains have provided valuable insights into how experimentally identified conserved motifs contribute to the telomerase reverse transcriptase reaction. Additionally, structures of telomere-associated proteins in a variety of organisms have revealed that, across evolution, telomere-maintenance mechanisms employ common structural elements. For example, the single-stranded 3' overhang of telomeric DNA is specifically and tightly bound by an OB-fold in nearly all species, including ciliates (TEBP and Pot1a), fission yeast (SpPot1), budding yeast (Cdc13), and humans (hPOT1). Structures of the yeast Cdc13, Stn1, and Ten1 proteins demonstrated that telomere maintenance is regulated by a complex that bears significant similarity to the RPA heterotrimer. Similarly, proteins that specifically bind double-stranded telomeric DNA in divergent species use homeodomains to execute their functions (human TRF1 and TRF2 and budding yeast ScRap1). Likewise, the conserved protein Rap1, which is found in budding yeast, fission yeast, and humans, contains a structural motif that is known to be critical for protein-protein interaction. In addition to revealing the common underlying themes of telomere maintenance, structures have also elucidated the specific mechanisms by which many of these proteins function, including identifying a telomere-specific domain in Stn1 and how the human TRF proteins avoid heterodimerization. In this review, we summarize the high-resolution structures of telomerase and telomere-associated proteins and discuss the emergent common structural themes among these proteins. We also address how these high-resolution structures complement biochemical and cellular studies to enhance our understanding of telomere maintenance and function.

  7. Analysis of flexible structures under lateral impact

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, D. F. [Paul C. Kizzo and Associates Inc., Seismic Structural Group, Oakland, CA 94612 (United States); Razavi, H. [AREVA Inc., Civil Seismic Group, San Jose, CA 95119 (United States)

    2012-07-01

    Three methods for analysis of flexible structures under lateral impact are presented. The first proposed method (Method A) consists of: (1) modifying an available deceleration on a rigid target with conservation principles to account for structural flexibility; and (2) transient nonlinear analysis of the structure with the corrected forcing function. The second proposed method (Method B) is similar to Method A in obtaining the forcing function but it solves the equations of motion of an idealized two-degree-of-freedom system instead of directly using conservation principles. The last method simply provides the maximum force in the structure using the conservation of energy and linear momentum. A coupled simulation is also performed in LS-DYNA and compared against the proposed methods. A case study is presented to illustrate the applicability of all three methods and the LS-DYNA simulation. (authors)

  8. Tunnel Probabilistic Structural Analysis Using the FORM

    OpenAIRE

    Yousef Mirzaeian; Kourosh Shahriar; Mostafa Sharifzadeh

    2015-01-01

    In this paper tunnel probabilistic structural analysis (TuPSA) was performed using the first order reliability method (FORM). In TuPSA, a tunnel performance function is defined according to the boundary between the structural stability and instability. Then the performance function is transformed from original space into the standard normal variable space to obtain the design point, reliability index, and also the probability of tunnel failure. In this method, it is possible to consider the d...

  9. Numerical analysis of shell and spatial structures

    OpenAIRE

    Samartín, Avelino

    1991-01-01

    Since the advent of the computer into the engineering field, the application of the numerical methods to the solution of engineering problems has grown very rapidly. Among the different computer methods of structural analysis the Finite Element (FEM) has been predominantly used. Shells and space structures are very attractive and have been constructed to solve a large variety of functional problems (roofs, industrial building, aqueducts, reservoirs, footings etc). In this type of structu...

  10. Data structures and algorithm analysis in Java

    CERN Document Server

    Shaffer, Clifford A

    2011-01-01

    With its focus on creating efficient data structures and algorithms, this comprehensive text helps readers understand how to select or design the tools that will best solve specific problems. It uses Java as the programming language and is suitable for second-year data structure courses and computer science courses in algorithm analysis. Techniques for representing data are presented within the context of assessing costs and benefits, promoting an understanding of the principles of algorithm analysis and the effects of a chosen physical medium. The text also explores tradeoff issues, familiari

  11. Data structures and algorithm analysis in C++

    CERN Document Server

    Shaffer, Clifford A

    2011-01-01

    With its focus on creating efficient data structures and algorithms, this comprehensive text helps readers understand how to select or design the tools that will best solve specific problems. It uses Microsoft C++ as the programming language and is suitable for second-year data structure courses and computer science courses in algorithm analysis.Techniques for representing data are presented within the context of assessing costs and benefits, promoting an understanding of the principles of algorithm analysis and the effects of a chosen physical medium. The text also explores tradeoff issues, f

  12. Geographical data structures supporting regional analysis

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, R.G.; Durfee, R.C.

    1978-01-01

    In recent years the computer has become a valuable aid in solving regional environmental problems. Over a hundred different geographic information systems have been developed to digitize, store, analyze, and display spatially distributed data. One important aspect of these systems is the data structure (e.g. grids, polygons, segments) used to model the environment being studied. This paper presents eight common geographic data structures and their use in studies of coal resources, power plant siting, population distributions, LANDSAT imagery analysis, and landuse analysis.

  13. From Microactions to Macrostructure and Back: A Structurational Approach to the Evolution of Organizational Networks

    Science.gov (United States)

    Whitbred, Robert; Fonti, Fabio; Steglich, Christian; Contractor, Noshir

    2011-01-01

    Structuration theory (ST) and network analysis are promising approaches for studying the emergence of communication networks. We offer a model that integrates the conceptual richness of structuration with the precision of relevant concepts and mechanisms offered from communication network research. We leverage methodological advancements (i.e.,…

  14. Advection of the salt wedge and evolution of the internal flow structure in the Rotterdam Waterway

    NARCIS (Netherlands)

    De Nijs, M.A.J.; Pietrzak, J.D.; Winterwerp, J.C.

    2011-01-01

    An analysis of field measurements recorded over a tidal cycle in the Rotterdam Waterway is presented. These measurements are the first to elucidate the processes influencing the along-channel current structure and the excursion of the salt wedge in this estuary. The salt wedge structure remained sta

  15. RNA Secondary Structure Analysis Using RNAstructure.

    Science.gov (United States)

    Mathews, David H

    2014-06-17

    RNAstructure is a user-friendly program for the prediction and analysis of RNA secondary structure. It is available as a Web server, as a program with a graphical user interface, or as a set of command-line tools. The programs are available for Microsoft Windows, Macintosh OS X, or Linux. This unit provides protocols for RNA secondary structure prediction (using the Web server or the graphical user interface) and prediction of high-affinity oligonucleotide biding sites to a structured RNA target (using the graphical user interface).

  16. MBS Analysis Of Kinetic Structures Using ADAMS

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R.K.

    2009-01-01

    The present paper considers multibody system (MBS) analysis of kinetic structures using the software package ADAMS. Deployable, foldable, expandable and reconfigurable kinetic structures can provide a change in the geometric morphology of the envelope by contributing to making it adaptable to e......-called multibody system (MBS) formalism. The present paper considers MBS modeling of kinetic architectural structures using the software packages ADAMS. As a result, it is found that symbolic MBS simulation tools facilitate a useful evaluation environment for MBS users during a design phase of responsive kinetic...

  17. Nation-Wide Mobile Network Energy Evolution Analysis

    DEFF Research Database (Denmark)

    Perez, Eva; Frank, Philipp; Micallef, Gilbert;

    2013-01-01

    Mobile network operators are facing a challenging dilemma. While on the one hand they are committed to reducing their carbon emissions, and energy consumption, they are also required to continuously upgrade existing networks, ensuring that the relentless growth in data traffic can still...... be supported. In most cases, these upgrades increase the energy consumption of the network even further. This paper presents a nation-wide case study, based on a commercial network of a leading European operator, intended to provide a clear understanding of how the energy consumption of mobile networks...... is expected to evolve from 2012 until 2020. The study also considers an efficient network capacity evolution path, including base station equipment improvement forecasts....

  18. Analysis of the Evolution of Unemployment in Romania

    Directory of Open Access Journals (Sweden)

    Palade A.

    2014-12-01

    Full Text Available The main objective of this paper is to evaluate the existing situation of the labour market, from the unemployment standpoint. The present article begins by reviewing the literature and goes on to analyse the evolution of unemployment in Romania. The present study indicates that unemployment is higher among men than among women. This phenomenon has become apparent after the economic crisis, when the fields most affected were production and constructions in which most employees are male. It is predicted that the large number of unemployed individuals will not be diminished, even after the end of the crisis. Even if the economy returns to normal and consumers begin using consumer goods again, this increase will only be able to absorb a small fraction of the unemployed.

  19. Statistical analysis on adaptive evolution of SQUA genes in angiosperms

    Institute of Scientific and Technical Information of China (English)

    CHEN Yongyan; ZHONG Yang; TIAN Bo; YANG Ji; LI Dezhu

    2005-01-01

    SQUAMOSA (SQUA) subfamily includes important perianth identity genes of MADS-box gene family. SQUA genes of Dendrocalamus latiflorus were sequenced, and phylogenetic form on SQUA genes in angiosperms was analyzed. Relative rate and adaptive evolution after SQUA gene duplication in recent common ancestor of monocots and eudicots were analyzed using the methods of relative rate test, statistic on synonymous and non-synonymous coden substitution sites and likelihood rate test. The results show that both of relative rate and synonymous and non-synonymous coden substitution in eudicot clade are significantly higher than those in monocot clade, and the value of dN/ds uncovered possible positive selective pressure in eudicot clade.

  20. Residential energy use in Mexico: Structure, evolution, environmental impacts, and savings potential

    Energy Technology Data Exchange (ETDEWEB)

    Masera, O.; Friedmann, R.; deBuen, O.

    1993-05-01

    This article examines the characteristics of residential energy use in Mexico, its environmental impacts, and the savings potential of the major end-uses. The main options and barriers to increase the efficiency of energy use are discussed. The energy analysis is based on a disaggregation of residential energy use by end-uses. The dynamics of the evolution of the residential energy sector during the past 20 years are also addressed when the information is available. Major areas for research and for innovative decision-making are identified and prioritized.