WorldWideScience

Sample records for space influence evolution

  1. Evolution to Space

    Science.gov (United States)

    Cohen, Jacob

    2013-01-01

    This presentation will discuss recent space exploration results (LCROSS, KEPLER, etc.), increase access to space and the small and cube satellites platform as it relates to the future of space exploration. It will highlight the concept of modularization and the use of biology, and specifically synthetic biology in the future. The presentation will be a general public presentation. When speaking to a younger audience, I will discuss my background. All slides contain only public information. No technical ITAR/Export controlled material will be discussed.

  2. The influence of space and time on the evolution of altruistic defence: the case of ant slave rebellion.

    Science.gov (United States)

    Metzler, D; Jordan, F; Pamminger, T; Foitzik, S

    2016-05-01

    How can antiparasite defence traits evolve even if they do not directly benefit their carriers? An example of such an indirect defence is rebellion of enslaved Temnothorax longispinosus ant workers against their social parasite Temnothorax americanus, a slavemaking ant. Ant slaves have been observed to kill their oppressors' offspring, a behaviour from which the sterile slaves cannot profit directly. Parasite brood killing could, however, reduce raiding pressure on related host colonies nearby. We analyse with extensive computer simulations for the Temnothorax slavemaker system under what conditions a hypothetical rebel allele could invade a host population, and in particular, how host-parasite dynamics and population structure influence the rebel allele's success. Exploring a wide range of model parameters, we only found a small number of parameter combinations for which kin selection or multilevel selection could allow a slave rebellion allele to spread in the host population. Furthermore, we did not detect any cases in which the reduction of raiding pressure in the close vicinity of the slavemaker nest would substantially contribute to the inclusive fitness of rebels. This suggests that slave rebellion is not costly and perhaps a side-effect of some other beneficial trait. In some of our simulations, however, even a costly rebellion allele could spread in the population. This was possible when host-parasite interactions led to a metapopulation dynamic with frequent local extinctions and recolonizations of demes by the offspring of few immigrants. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  3. Space station evolution: Planning for the future

    Science.gov (United States)

    Diaz, Alphonso V.; Askins, Barbara S.

    1987-06-01

    The need for permanently manned presence in space has been recognized by the United States and its international partners for many years. The development of this capability was delayed due to the concurrent recognition that reusable earth-to-orbit transportation was also needed and should be developed first. While the decision to go ahead with a permanently manned Space Station was on hold, requirements for the use of the Station were accumulating as ground-based research and the data from unmanned spacecraft sparked the imagination of both scientists and entrepreneurs. Thus, by the time of the Space Station implementation decision in the early 1980's, a variety of disciplines, with a variety of requirements, needed to be accommodated on one Space Station. Additional future requirements could be forecast for advanced missions that were still in the early planning stages. The logical response was the development of a multi-purpose Space Station with the ability to evolve on-orbit to new capabilities as required by user needs and national or international decisions, i.e., to build an evolutionary Space Station. Planning for evolution is conducted in parallel with the design and development of the baseline Space Station. Evolution planning is a strategic management process to facilitate change and protect future decisions. The objective is not to forecast the future, but to understand the future options and the implications of these on today's decisions. The major actions required now are: (1) the incorporation of evolution provisions (hooks and scars) in the baseline Space Station; and (2) the initiation of an evolution advanced development program.

  4. Space station evolution: Planning for the future

    Science.gov (United States)

    Diaz, Alphonso V.; Askins, Barbara S.

    1987-01-01

    The need for permanently manned presence in space has been recognized by the United States and its international partners for many years. The development of this capability was delayed due to the concurrent recognition that reusable earth-to-orbit transportation was also needed and should be developed first. While the decision to go ahead with a permanently manned Space Station was on hold, requirements for the use of the Station were accumulating as ground-based research and the data from unmanned spacecraft sparked the imagination of both scientists and entrepreneurs. Thus, by the time of the Space Station implementation decision in the early 1980's, a variety of disciplines, with a variety of requirements, needed to be accommodated on one Space Station. Additional future requirements could be forecast for advanced missions that were still in the early planning stages. The logical response was the development of a multi-purpose Space Station with the ability to evolve on-orbit to new capabilities as required by user needs and national or international decisions, i.e., to build an evolutionary Space Station. Planning for evolution is conducted in parallel with the design and development of the baseline Space Station. Evolution planning is a strategic management process to facilitate change and protect future decisions. The objective is not to forecast the future, but to understand the future options and the implications of these on today's decisions. The major actions required now are: (1) the incorporation of evolution provisions (hooks and scars) in the baseline Space Station; and (2) the initiation of an evolution advanced development program.

  5. FACTORS INFLUENCING THE EVOLUTION OF YOUTH TRAVEL

    Directory of Open Access Journals (Sweden)

    Student Claudia MOISĂ

    2010-01-01

    Full Text Available Youth travel is an important part of global tourism, consequently, getting to know the evolution of this form of tourism requires an approach of the aspects regarding the permissive and restrictive factors that influence the youth travel dynamic worldwide. In terms of the factors that influence youth travel, we highlighted these two categories of factors (permissive and restrictive and, within each category, we tried to singularize the influence of every factor over youth travel.

  6. Can IVF influence human evolution?

    Science.gov (United States)

    Hanevik, Hans Ivar; Hessen, Dag O; Sunde, Arne; Breivik, Jarle

    2016-07-01

    IVF, a procedure in which pharmacological and technological manipulation is used to promote pregnancy, offers help to infertile couples by circumventing selection at the most fundamental level. Fertility is clearly one of the key fitness-promoting drivers in all forms of sexually reproducing life, and fertilization and pregnancy are fundamental evolutionary processes that involve a range of pre- and post-zygotic screening mechanisms. Here, we discuss the various selection and screening factors involved in fertilization and pregnancy and assess IVF practices in light of these factors. We then focus on the possible consequences of these differences in selection pressures, mainly at the individual but also at the population level, to evaluate whether changes in the reproducing genotype can affect human evolution. The aim of the article is not to argue for or against IVF, but to address aspects of assisted reproduction in an evolutionary context. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. The evolution of organic matter in space.

    Science.gov (United States)

    Ehrenfreund, Pascale; Spaans, Marco; Holm, Nils G

    2011-02-13

    Carbon, and molecules made from it, have already been observed in the early Universe. During cosmic time, many galaxies undergo intense periods of star formation, during which heavy elements like carbon, oxygen, nitrogen, silicon and iron are produced. Also, many complex molecules, from carbon monoxide to polycyclic aromatic hydrocarbons, are detected in these systems, like they are for our own Galaxy. Interstellar molecular clouds and circumstellar envelopes are factories of complex molecular synthesis. A surprisingly high number of molecules that are used in contemporary biochemistry on the Earth are found in the interstellar medium, planetary atmospheres and surfaces, comets, asteroids and meteorites and interplanetary dust particles. Large quantities of extra-terrestrial material were delivered via comets and asteroids to young planetary surfaces during the heavy bombardment phase. Monitoring the formation and evolution of organic matter in space is crucial in order to determine the prebiotic reservoirs available to the early Earth. It is equally important to reveal abiotic routes to prebiotic molecules in the Earth environments. Materials from both carbon sources (extra-terrestrial and endogenous) may have contributed to biochemical pathways on the Earth leading to life's origin. The research avenues discussed also guide us to extend our knowledge to other habitable worlds.

  8. Community Factors Influencing Birth Spacing among Married ...

    African Journals Online (AJOL)

    AJRH Managing Editor

    level factors on birth spacing behaviour in Uganda and Zimbabwe, to ... environments as potential influences on birth spacing ..... health: multivariable cross-country analysis, MACRO ... Equity monitoring for social marketing: Use of wealth.

  9. Mantle flow influence on subduction evolution

    Science.gov (United States)

    Chertova, Maria V.; Spakman, Wim; Steinberger, Bernhard

    2018-05-01

    The impact of remotely forced mantle flow on regional subduction evolution is largely unexplored. Here we investigate this by means of 3D thermo-mechanical numerical modeling using a regional modeling domain. We start with simplified models consisting of a 600 km (or 1400 km) wide subducting plate surrounded by other plates. Mantle inflow of ∼3 cm/yr is prescribed during 25 Myr of slab evolution on a subset of the domain boundaries while the other side boundaries are open. Our experiments show that the influence of imposed mantle flow on subduction evolution is the least for trench-perpendicular mantle inflow from either the back or front of the slab leading to 10-50 km changes in slab morphology and trench position while no strong slab dip changes were observed, as compared to a reference model with no imposed mantle inflow. In experiments with trench-oblique mantle inflow we notice larger effects of slab bending and slab translation of the order of 100-200 km. Lastly, we investigate how subduction in the western Mediterranean region is influenced by remotely excited mantle flow that is computed by back-advection of a temperature and density model scaled from a global seismic tomography model. After 35 Myr of subduction evolution we find 10-50 km changes in slab position and slab morphology and a slight change in overall slab tilt. Our study shows that remotely forced mantle flow leads to secondary effects on slab evolution as compared to slab buoyancy and plate motion. Still these secondary effects occur on scales, 10-50 km, typical for the large-scale deformation of the overlying crust and thus may still be of large importance for understanding geological evolution.

  10. Evolution in space and time of two interacting intensities

    International Nuclear Information System (INIS)

    Wilhelmsson, H.

    1977-01-01

    The basic nonlinear coupled equations describing the interaction between two intensities (or two populations) are discussed. Analytic solutions are deduced for the evolution in space and time of initially given perturbations of the equilibrium intensities. (Auth.)

  11. History and Evolution of Active Learning Spaces

    Science.gov (United States)

    Beichner, Robert J.

    2014-01-01

    This chapter examines active learning spaces as they have developed over the years. Consistently well-designed classrooms can facilitate active learning even though the details of implementing pedagogies may differ.

  12. Exploring galaxy evolution with latent space walks

    Science.gov (United States)

    Schawinski, Kevin; Turp, Dennis; Zhang, Ce

    2018-01-01

    We present a new approach using artificial intelligence to perform data-driven forward models of astrophysical phenomena. We describe how a variational autoencoder can be used to encode galaxies to latent space, independently manipulate properties such as the specific star formation rate, and return it to real space. Such transformations can be used for forward modeling phenomena using data as the only constraints. We demonstrate the utility of this approach using the question of the quenching of star formation in galaxies.

  13. Time-space noncommutativity: quantised evolutions

    International Nuclear Information System (INIS)

    Balachandran, Aiyalam P.; Govindarajan, Thupil R.; Teotonio-Sobrinho, Paulo; Martins, Andrey Gomes

    2004-01-01

    In previous work, we developed quantum physics on the Moyal plane with time-space noncommutativity, basing ourselves on the work of Doplicher et al. Here we extend it to certain noncommutative versions of the cylinder, R 3 and Rx S 3 . In all these models, only discrete time translations are possible, a result known before in the first two cases. One striking consequence of quantised time translations is that even though a time independent hamiltonian is an observable, in scattering processes, it is conserved only modulo 2π/θ, where θ is the noncommutative parameter. (In contrast, on a one-dimensional periodic lattice of lattice spacing a and length L = Na, only momentum mod 2π/L is observable (and can be conserved).) Suggestions for further study of this effect are made. Scattering theory is formulated and an approach to quantum field theory is outlined. (author)

  14. Critical spaces for quasilinear parabolic evolution equations and applications

    Science.gov (United States)

    Prüss, Jan; Simonett, Gieri; Wilke, Mathias

    2018-02-01

    We present a comprehensive theory of critical spaces for the broad class of quasilinear parabolic evolution equations. The approach is based on maximal Lp-regularity in time-weighted function spaces. It is shown that our notion of critical spaces coincides with the concept of scaling invariant spaces in case that the underlying partial differential equation enjoys a scaling invariance. Applications to the vorticity equations for the Navier-Stokes problem, convection-diffusion equations, the Nernst-Planck-Poisson equations in electro-chemistry, chemotaxis equations, the MHD equations, and some other well-known parabolic equations are given.

  15. Evolution of new materials for space applications

    International Nuclear Information System (INIS)

    Purdy, D.M.

    1983-01-01

    The implications of spacecraft design requirements for materials technology are surveyed, with a focus on current trends and future needs. Criteria for materials selection are discussed, including contamination control (low-outgassing materials), electrical and thermal characteristics, structural stiffness, safety requirements, and survivability (under natural space conditions for longer periods and under potential hostile particle-beam or laser attack). The applications and potential of polymer-matrix, metal-matrix and ceramic-matrix composites are discussed and compared. While polymer-matrix-material applications are seen as extendable by using high-stiffness fibers and improving ultraviolet protection, the greatest potential is seen in the development of the metal-matrix and ceramic-matrix composites, as used in the Space Shuttle. A need for cheaper, lighter, more radiation-resistant and less contamination-prone thermal-control coatings than the present optical-solar-reflector tiles, silica fabric, and indium-tin-oxide coating is projected. Methods for the analysis of structural defects in viscoelastic electrical components are presented. The materials requirements of larger and more powerful future spacecraft are evaluated. 17 references

  16. Community Factors Influencing Birth Spacing among Married ...

    African Journals Online (AJOL)

    The significance of community-level demographic and fertility norms, gender norms, economic prosperity, and family planning behaviors demonstrate the broad influence of community variables on birth spacing outcomes. This analysis highlights the importance of moving beyond individual and household-level ...

  17. Geometric differential evolution for combinatorial and programs spaces.

    Science.gov (United States)

    Moraglio, A; Togelius, J; Silva, S

    2013-01-01

    Geometric differential evolution (GDE) is a recently introduced formal generalization of traditional differential evolution (DE) that can be used to derive specific differential evolution algorithms for both continuous and combinatorial spaces retaining the same geometric interpretation of the dynamics of the DE search across representations. In this article, we first review the theory behind the GDE algorithm, then, we use this framework to formally derive specific GDE for search spaces associated with binary strings, permutations, vectors of permutations and genetic programs. The resulting algorithms are representation-specific differential evolution algorithms searching the target spaces by acting directly on their underlying representations. We present experimental results for each of the new algorithms on a number of well-known problems comprising NK-landscapes, TSP, and Sudoku, for binary strings, permutations, and vectors of permutations. We also present results for the regression, artificial ant, parity, and multiplexer problems within the genetic programming domain. Experiments show that overall the new DE algorithms are competitive with well-tuned standard search algorithms.

  18. Evolution in Many-Sheeted Space-time

    OpenAIRE

    Pitkänen, Matti

    2010-01-01

    The topics of the article has been restricted to those, which seem to represent the most well-established ideas about evolution in many-sheeted space-time. a) Basic facts about and TGD based model for pre-biotic evolution are discussed. b) A model for the ATP-ADP process based on DNA as topological quantum computer vision, the identification of universal metabolic energy quanta in terms of zero point kinetic energies, and the notion of remote metabolism is discussed. c) A model f...

  19. Space Shuttle GN and C Development History and Evolution

    Science.gov (United States)

    Zimpfer, Douglas; Hattis, Phil; Ruppert, John; Gavert, Don

    2011-01-01

    Completion of the final Space Shuttle flight marks the end of a significant era in Human Spaceflight. Developed in the 1970 s, first launched in 1981, the Space Shuttle embodies many significant engineering achievements. One of these is the development and operation of the first extensive fly-by-wire human space transportation Guidance, Navigation and Control (GN&C) System. Development of the Space Shuttle GN&C represented first time inclusions of modern techniques for electronics, software, algorithms, systems and management in a complex system. Numerous technical design trades and lessons learned continue to drive current vehicle development. For example, the Space Shuttle GN&C system incorporated redundant systems, complex algorithms and flight software rigorously verified through integrated vehicle simulations and avionics integration testing techniques. Over the past thirty years, the Shuttle GN&C continued to go through a series of upgrades to improve safety, performance and to enable the complex flight operations required for assembly of the international space station. Upgrades to the GN&C ranged from the addition of nose wheel steering to modifications that extend capabilities to control of the large flexible configurations while being docked to the Space Station. This paper provides a history of the development and evolution of the Space Shuttle GN&C system. Emphasis is placed on key architecture decisions, design trades and the lessons learned for future complex space transportation system developments. Finally, some of the interesting flight operations experience is provided to inform future developers of flight experiences.

  20. Influence of space radiation on satellite magnetics

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, M K [Vikram Sarabhai Space Centre, Trivandrum (India)

    1978-12-01

    The magnetic circuits and devices used in space-borne systems such as satellites are naturally exposed to space environments having among others, hazardous radiations. Such radiations, in turn, may be of solar, cosmic or nuclear origin depending upon the altitude as well as the propulsion/power systems involving mini atomic reactors when utilised. The influence of such radiations on the magnetic components of the satellite have been analysed revealing the critical hazards in the latter circuits system. Remedial measures by appropriate shielding, etc. necessary for maintaining optimum performance of the satellite have been discussed.

  1. Phase-space formalism: Operational calculus and solution of evolution equations in phase-space

    International Nuclear Information System (INIS)

    Dattoli, G.; Torre, A.

    1995-05-01

    Phase-space formulation of physical problems offers conceptual and practical advantages. A class of evolution type equations, describing the time behaviour of a physical system, using an operational formalism useful to handle time ordering problems has been described. The methods proposed generalize the algebraic ordering techniques developed to deal with the ordinary Schroedinger equation, and how they are taylored suited to treat evolution problems both in classical and quantum dynamics has been studied

  2. Evolution of space food in Nostoc sp. HK-01

    Science.gov (United States)

    Tomita-Yokotani, Kaori; Yamashita, Masamichi; Hashimoto, Hirofumi; Sato, Seigo; Kimura, Yasuko; Katoh, Hiroshi; Arai, Mayumi

    2012-07-01

    Habitation in outer space is one of our challenges. We have been studying future space agriculture to provide food and oxygen for the habitation area in the space environment, on Mars. A cyanobacteria, Nostoc sp. HK-01, has high several outer space environmental tolerance. We have already confirmed that Nostoc sp.HK-01 had an ability to grow for over several years on the Martian regolith simulant in a laboratory experiment. Nostoc sp HK-01 would have high contribution to change the atmosphere in Mars as a photosynthetic creature. In outer environment, all of materials have to circulate for all of creature living in artificial eco-systems on Mars. This material has several functions as the utilization in space agriculture. Here, we are proposing using them as a food after its growing on Mars. We are trying to determine the best conditions and evolution for space food using Nostoc sp.HK-01 and studying the proposal of utilization of cyanobacteria, Nostoc sp HK-01, for the variation of meal as space agriculture.

  3. Space and time evolution of two nonlinearly coupled variables

    International Nuclear Information System (INIS)

    Obayashi, H.; Totsuji, H.; Wilhelmsson, H.

    1976-12-01

    The system of two coupled linear differential equations are studied assuming that the coupling terms are proportional to the product of the dependent variables, representing e.g. intensities or populations. It is furthermore assumed that these variables experience different linear dissipation or growth. The derivations account for space as well as time dependence of the variables. It is found that certain particular solutions can be obtained to this system, whereas a full solution in space and time as an initial value problem is outside the scope of the present paper. The system has a nonlinear equilibrium solution for which the nonlinear coupling terms balance the terms of linear dissipation. The case of space and time evolution of a small perturbation of the nonlinear equilibrium state, given the initial one-dimensional spatial distribution of the perturbation, is also considered in some detail. (auth.)

  4. An x-space analysis of evolution equations: Soffer's inequality and the non-forward evolution

    International Nuclear Information System (INIS)

    Cafarella, Alessandro; Coriano, Claudio; Guzzi, Marco

    2003-01-01

    We analyze the use of algorithms based in x-space for the solution of renormalization group equations of DGLAP-type and test their consistency by studying bounds among partons distributions - in our specific case Soffer's inequality and the perturbative behaviour of the nucleon tensor charge - to next-to-leading order in QCD. A discussion of the perturbative resummation implicit in these expansions using Mellin moments is included. We also comment on the (kinetic) proof of positivity of the evolution of h1, using a kinetic analogy and illustrate the extension of the algorithm to the evolution of generalized parton distributions. We prove positivity of the non-forward evolution in a special case and illustrate a Fokker-Planck approximation to it. (author)

  5. Random sampling of evolution time space and Fourier transform processing

    International Nuclear Information System (INIS)

    Kazimierczuk, Krzysztof; Zawadzka, Anna; Kozminski, Wiktor; Zhukov, Igor

    2006-01-01

    Application of Fourier Transform for processing 3D NMR spectra with random sampling of evolution time space is presented. The 2D FT is calculated for pairs of frequencies, instead of conventional sequence of one-dimensional transforms. Signal to noise ratios and linewidths for different random distributions were investigated by simulations and experiments. The experimental examples include 3D HNCA, HNCACB and 15 N-edited NOESY-HSQC spectra of 13 C 15 N labeled ubiquitin sample. Obtained results revealed general applicability of proposed method and the significant improvement of resolution in comparison with conventional spectra recorded in the same time

  6. Evolution of the large Deep Space Network antennas

    Science.gov (United States)

    Imbriale, William A.

    1991-12-01

    The evolution of the largest antenna of the US NASA Deep Space Network (DSN) is described. The design, performance analysis, and measurement techniques, beginning with its initial 64-m operation at S-band (2295 MHz) in 1966 and continuing through the present ka-band (32-GHz) operation at 70 m, is described. Although their diameters and mountings differ, these parabolic antennas all employ a Cassegrainian feed system, and each antenna dish surface is constructed of precision-shaped perforated-aluminum panels that are secured to an open steel framework

  7. Yearbook on space policy 2015 access to space and the evolution of space activities

    CERN Document Server

    Baranes, Blandina; Hulsroj, Peter; Lahcen, Arne

    2017-01-01

    The Yearbook on Space Policy, edited by the European Space Policy Institute (ESPI), is the reference publication analysing space policy developments. Each year it presents issues and trends in space policy and the space sector as a whole. Its scope is global and its perspective is European. The Yearbook also links space policy with other policy areas. It highlights specific events and issues, and provides useful insights, data and information on space activities. The first part of the Yearbook sets out a comprehensive overview of the economic, political, technological and institutional trends that have affected space activities. The second part of the Yearbook offers a more analytical perspective on the yearly ESPI theme and consists of external contributions written by professionals with diverse backgrounds and areas of expertise. The third part of the Yearbook carries forward the character of the Yearbook as an archive of space activities. The Yearbook is designed for government decision-makers and agencies...

  8. Factors Potentially Influencing Student Acceptance of Biological Evolution

    Science.gov (United States)

    Wiles, Jason R.

    This investigation explored scientific, religious, and otherwise nonscientific factors that may influence student acceptance of biological evolution and related concepts, how students perceived these factors to have influenced their levels of acceptance of evolution and changes therein, and what patterns arose among students' articulations of how their levels of acceptance of evolution may have changed. This exploration also measured the extent to which students' levels of acceptance changed following a treatment designed to address factors identified as potentially affecting student acceptance of evolution. Acceptance of evolution was measured using the MATE instrument (Rutledge and Warden, 1999; Rutledge and Sadler, 2007) among participants enrolled in a secondary-level academic program during the summer prior to their final year of high school and as they transitioned to the post-secondary level. Student acceptance of evolution was measured to be significantly higher than pre-treatment levels both immediately following and slightly over one year after treatment. Qualitative data from informal questionnaires, from formal course evaluations, and from semi-structured interviews of students engaged in secondary level education and former students at various stages of post-secondary education confirmed that the suspected factors were perceived by participants to have influenced their levels of acceptance of evolution. Furthermore, participant reports provided insight regarding the relative effects they perceived these factors to have had on their evolution acceptance levels. Additionally, many participants reported that their science teachers in public schools had avoided, omitted, or denigrated evolution during instruction, and several of these students expressed frustration regarding what they perceived to have been a lack of education of an important scientific principle. Finally, no students expressed feelings of being offended by having been taught about

  9. Quantum dynamical time evolutions as stochastic flows on phase space

    International Nuclear Information System (INIS)

    Combe, P.; Rodriguez, R.; Guerra, F.; Sirigue, M.; Sirigue-Collin, M.

    1984-01-01

    We are mainly interested in describing the time development of the Wigner functions by means of stochastic processes. In the second section we recall the main properties of the Wigner functions as well as those of their Fourier transform. In the next one we derive the evolution equation of these functions for a class of Hamiltonians and we give a probabilistic expression for the solution of these equations by means of a stochastic flow in phase space which reminds of the classical flows. In the last section we remark that the previously defined flow can be extended to the bounded continuous functions on phase space and that this flow conserves the cone generated by the Wigner functions. (orig./HSI)

  10. Human influences on evolution, and the ecological and societal consequences.

    Science.gov (United States)

    Hendry, Andrew P; Gotanda, Kiyoko M; Svensson, Erik I

    2017-01-19

    Humans have dramatic, diverse and far-reaching influences on the evolution of other organisms. Numerous examples of this human-induced contemporary evolution have been reported in a number of 'contexts', including hunting, harvesting, fishing, agriculture, medicine, climate change, pollution, eutrophication, urbanization, habitat fragmentation, biological invasions and emerging/disappearing diseases. Although numerous papers, journal special issues and books have addressed each of these contexts individually, the time has come to consider them together and thereby seek important similarities and differences. The goal of this special issue, and this introductory paper, is to promote and expand this nascent integration. We first develop predictions as to which human contexts might cause the strongest and most consistent directional selection, the greatest changes in evolutionary potential, the greatest genetic (as opposed to plastic) changes and the greatest effects on evolutionary diversification We then develop predictions as to the contexts where human-induced evolutionary changes might have the strongest effects on the population dynamics of the focal evolving species, the structure of their communities, the functions of their ecosystems and the benefits and costs for human societies. These qualitative predictions are intended as a rallying point for broader and more detailed future discussions of how human influences shape evolution, and how that evolution then influences species traits, biodiversity, ecosystems and humans.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'. © 2016 The Author(s).

  11. Trophic specialization influences the rate of environmental niche evolution in damselfishes (Pomacentridae).

    Science.gov (United States)

    Litsios, Glenn; Pellissier, Loïc; Forest, Félix; Lexer, Christian; Pearman, Peter B; Zimmermann, Niklaus E; Salamin, Nicolas

    2012-09-22

    The rate of environmental niche evolution describes the capability of species to explore the available environmental space and is known to vary among species owing to lineage-specific factors. Trophic specialization is a main force driving species evolution and is responsible for classical examples of adaptive radiations in fishes. We investigate the effect of trophic specialization on the rate of environmental niche evolution in the damselfish, Pomacentridae, which is an important family of tropical reef fishes. First, phylogenetic niche conservatism is not detected in the family using a standard test of phylogenetic signal, and we demonstrate that the environmental niches of damselfishes that differ in trophic specialization are not equivalent while they still overlap at their mean values. Second, we estimate the relative rates of niche evolution on the phylogenetic tree and show the heterogeneity among rates of environmental niche evolution of the three trophic groups. We suggest that behavioural characteristics related to trophic specialization can constrain the evolution of the environmental niche and lead to conserved niches in specialist lineages. Our results show the extent of influence of several traits on the evolution of the environmental niche and shed new light on the evolution of damselfishes, which is a key lineage in current efforts to conserve biodiversity in coral reefs.

  12. Expanding P450 catalytic reaction space through evolution and engineering

    Science.gov (United States)

    McIntosh, John A.; Farwell, Christopher C.; Arnold, Frances H.

    2014-01-01

    Advances in protein and metabolic engineering have led to wider use of enzymes to synthesize important molecules. However, many desirable transformations are not catalyzed by any known enzyme, driving interest in understanding how new enzymes can be created. The cytochrome P450 enzyme family, whose members participate in xenobiotic metabolism and natural products biosynthesis, catalyzes an impressive range of difficult chemical reactions that continues to grow as new enzymes are characterized. Recent work has revealed that P450-derived enzymes can also catalyze useful reactions previously accessible only to synthetic chemistry. The evolution and engineering of these enzymes provides an excellent case study for how to genetically encode new chemistry and expand biology’s reaction space. PMID:24658056

  13. Asymptotically Almost Periodic Solutions of Evolution Equations in Banach Spaces

    Science.gov (United States)

    Ruess, W. M.; Phong, V. Q.

    Tile linear abstract evolution equation (∗) u'( t) = Au( t) + ƒ( t), t ∈ R, is considered, where A: D( A) ⊂ E → E is the generator of a strongly continuous semigroup of operators in the Banach space E. Starting from analogs of Kadets' and Loomis' Theorems for vector valued almost periodic Functions, we show that if σ( A) ∩ iR is countable and ƒ: R → E is [asymptotically] almost periodic, then every bounded and uniformly continuous solution u to (∗) is [asymptotically] almost periodic, provided e-λ tu( t) has uniformly convergent means for all λ ∈ σ( A) ∩ iR. Related results on Eberlein-weakly asymptotically almost periodic, periodic, asymptotically periodic and C 0-solutions of (∗), as well as on the discrete case of solutions of difference equations are included.

  14. Interoceptive influences on peripersonal space boundary.

    Science.gov (United States)

    Ardizzi, Martina; Ferri, Francesca

    2018-08-01

    Integration of body-related signals within the peripersonal space (PPS) contributes to bodily self-awareness. Whereas several studies have shown how individual PPS extension is shaped by external factors, e.g. during interactions with people and objects, no studies have looked at interoceptive influences on PPS extension. We exposed participants to an audio-tactile interaction task, to measure their PPS boundary (Session 1), and to a heartbeat counting task and a time estimation task, to specifically assess their interoceptive accuracy (Session 2). Participants' traits of private self-consciousness and social anxiety were also evaluated, to account for their possible effect on the relation between interoception and PPS representation. We found that higher interoceptive accuracy specifically predicts narrower PPS boundary. Moreover, this relation is moderated by individual traits of private self-consciousness, but not social anxiety. Extending the concept of interoceptive influences on exteroceptive body representations to PPS, our results, first, support the idea that a dynamic balance between intero-exteroceptive processing might represent a general principle underlying bodily self-awareness; second, they shed light on how interoception may affect also the way we interface with the external world. Finally, showing that, in order for interoceptive accuracy to be effective on the intero-exteroceptive balance, it is important that individuals tend to focus on inner sensations and feelings, our results suggest that a comprehensive intero-exteroceptive model of bodily self-awareness should be (at least) a three-dimensional model that includes individual self-consciousness traits. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Evolution of the Copernicus Space Component: preparing for tomorrow

    Science.gov (United States)

    Aschbacher, Josef

    2016-04-01

    external borders, natural resources handling and climate change among others. Copernicus has therefore to respond to the dynamics of the EU policies' priorities with the required rapidity and flexibility, bringing concrete results in terms of information and growth (Sentinels' evolution) and, at the same time, taking account of the continuity of existing Sentinels data and Services (Second Generation). The Sentinels' evolution, more time stringent than the Second Generation, is a joint EU-ESA endeavour just started concerning a CO2 monitoring mission. Other domains/techniques under investigation for future missions are: polar ice/ocean interferometric altimetry, thermal Infrared, soil moisture or hyper-spectral land imaging. This presentation will therefore give an overview of the current status and future perspectives of the Copernicus space component.

  16. Laboratory Calibration Studies in Support of ORGANICS on the International Space Station: Evolution of Organic Matter in Space

    Science.gov (United States)

    Ruiterkamp, R.; Ehrenfreund, P.; Halasinski, T.; Salama, F.; Foing, B.; Schmidt, W.

    2002-01-01

    This paper describes the scientific overview and current status of ORGANICS an exposure experiment performed on the International Space Station (ISS) to study the evolution of organic matter in space (PI: P. Ehrenfreund), with supporting laboratory experiments performed at NASA Ames. ORGANICS investigates the chemical evolution of samples submitted to long-duration exposure to space environment in near-Earth orbit. This experiment will provide information on the nature, evolution, and survival of carbon species in the interstellar medium (ISM) and in solar system targets.

  17. The influence of UV radiation on protistan evolution

    Science.gov (United States)

    Rothschild, L. J.

    1999-01-01

    Ultraviolet radiation has provided an evolutionary challenge to life on Earth. Recent increases in surficial ultraviolet B fluxes have focused attention on the role of UV radiation in protistan ecology, cancer, and DNA damage. Exploiting this new wealth of data, I examine the possibility that ultraviolet radiation may have played a significant role in the evolution of the first eukaryotes, that is, protists. Protists probably arose well before the formation of a significant ozone shield, and thus were probably subjected to substantial ultraviolet A, ultraviolet B, and ultraviolet C fluxes early in their evolution. Evolution consists of the generation of heritable variations and the subsequent selection of these variants. Ultraviolet radiation has played a role both as a mutagen and as a selective agent. In its role as a mutagen, it may have been crucial in the origin of sex and as a driver of molecular evolution. As a selective agent, its influence has been broad. Discussed in this paper are the influence of ultraviolet radiation on biogeography, photosynthesis, and desiccation resistance.

  18. The Influence of Stratigraphic History on Landscape Evolution

    Science.gov (United States)

    Forte, A. M.; Yanites, B.; Whipple, K. X.

    2016-12-01

    Variation in rock erodibility can play a significant role in landscape evolution. Using a version of the CHILD landscape evolution model that allows for variations in rock erodibility, we found surprisingly complex landscape evolution in simulations with simple, two unit stratigraphies with contrasting erodibility. This work indicated that the stratigraphic order of units in terms of erodibility, the orientation of the contact with respect to the main drainage direction, and the contact dip angle all have pronounced effects on landscape evolution. Here we expand that work to explore the implications of more complicated stratigraphies on landscape evolution. Introducing multiple units adds additional controls on landscape evolution, namely the thicknesses and relative erodibility of rock layers. In models with a sequence of five alternating hard and soft units embedded within arbitrarily thick over- and underlying units, the number of individual layers that noticeably influence landscape morphology decreases as the thickness of individual layers reduces. Contacts with soft rocks over hard produce the most noticeable effect in model output such as erosion rate and channel steepness. For large contrasts in erodibility of 25 m thick layers, only one soft over hard contact is clearly manifest in the landscape. Between 50 and 75 m, two such contacts are manifest, and by 100 m thickness, all three of these contacts are manifest. However, for a given thickness of layers, more units are manifest in the landscape as the erodibility contrast between units decreases. This is true even though the magnitude of landscape effects away from steady-state erosion rates or channel steepness also decrease with decreasing erodibility contrast. Finally, we explore suites of models with alternating layers reflecting either `hardening-' or `softening-upwards' stratigraphies and find that the two scenarios result in decidedly different landscape forms. Hardening-upwards sections produce a

  19. Second order evolution inclusions governed by sweeping process in Banach spaces

    Directory of Open Access Journals (Sweden)

    A. G. Ibrahim

    2009-11-01

    Full Text Available In this paper we prove two existence theorems concerning the existence of solutions for second order evolution inclusions governed by sweeping process with closed convex sets depending on time and state in Banach spaces. This work extends some recent existence theorems cncerning sweeping process from Hilbert spaces to Banach spaces.

  20. Modelling Influence and Opinion Evolution in Online Collective Behaviour.

    Directory of Open Access Journals (Sweden)

    Corentin Vande Kerckhove

    Full Text Available Opinion evolution and judgment revision are mediated through social influence. Based on a large crowdsourced in vitro experiment (n = 861, it is shown how a consensus model can be used to predict opinion evolution in online collective behaviour. It is the first time the predictive power of a quantitative model of opinion dynamics is tested against a real dataset. Unlike previous research on the topic, the model was validated on data which did not serve to calibrate it. This avoids to favor more complex models over more simple ones and prevents overfitting. The model is parametrized by the influenceability of each individual, a factor representing to what extent individuals incorporate external judgments. The prediction accuracy depends on prior knowledge on the participants' past behaviour. Several situations reflecting data availability are compared. When the data is scarce, the data from previous participants is used to predict how a new participant will behave. Judgment revision includes unpredictable variations which limit the potential for prediction. A first measure of unpredictability is proposed. The measure is based on a specific control experiment. More than two thirds of the prediction errors are found to occur due to unpredictability of the human judgment revision process rather than to model imperfection.

  1. Evolution of space drones for planetary exploration: A review

    Science.gov (United States)

    Hassanalian, M.; Rice, D.; Abdelkefi, A.

    2018-02-01

    In the past decade, there has been a tendency to design and fabricate drones which can perform planetary exploration. Generally, there are various ways to study space objects, such as the application of telescopes and satellites, launching robots and rovers, and sending astronauts to the targeted solar bodies. However, due to the advantages of drones compared to other approaches in planetary exploration, ample research has been carried out by different space agencies in the world, including NASA to apply drones in other solar bodies. In this review paper, several studies which have been performed on space drones for planetary exploration are consolidated and discussed. Design and fabrication challenges of space drones, existing methods for their flight tests, different methods for deployment and planet entry, and various navigation and control approaches are reviewed and discussed elaborately. Limitations of applying space drones, proposed solutions for future space drones, and recommendations are also presented and discussed.

  2. US Department of The Space Force: A Necessary Evolution

    Science.gov (United States)

    2012-05-15

    not dismayed; I am your God. I will strengthen you, and help you, and uphold you with my right hand. Isaiah 41:10 To my wife & children...Security Space: Report to Congress of the Independent Assessment Panel on the Organization and Management of National Security Space, by A. Thomas Young...Allard Commission Chairman, A. Thomas Young, concluded, “. . . there has been ‘no adult supervision’ in national security space.” 36 This

  3. Geometric approach to evolution problems in metric spaces

    NARCIS (Netherlands)

    Stojković, Igor

    2011-01-01

    This PhD thesis contains four chapters where research material is presented. In the second chapter the extension of the product formulas for semigroups induced by convex functionals, from the classical Hilbert space setting to the setting of general CAT(0) spaces. In the third chapter, the

  4. Evolution of telemedicine in the space program and earth applications

    Science.gov (United States)

    Nicogossian, A. E.; Pober, D. F.; Roy, S. A.

    2001-01-01

    Remote monitoring of crew, spacecraft, and environmental health has always been an integral part of the National Aeronautics and Space Administration's (NASA's) operations. Crew safety and mission success face a number of challenges in outerspace, including physiological adaptations to microgravity, radiation exposure, extreme temperatures and vacuum, and psychosocial reactions to space flight. The NASA effort to monitor and maintain crew health, system performance, and environmental integrity in space flight is a sophisticated and coordinated program of telemedicine combining cutting-edge engineering with medical expertise. As missions have increased in complexity, NASA telemedicine capabilities have grown apace, underlying its role in the field. At the same time, the terrestrial validation of telemedicine technologies to bring healthcare to remote locations provides feedback, improvement, and enhancement of the space program. As NASA progresses in its space exploration program, astronauts will join missions lasting months, even years, that take them millions of miles from home. These long-duration missions necessitate further technological breakthroughs in tele-operations and autonomous technology. Earth-based monitoring will no longer be real-time, requiring telemedicine capabilities to advance with future explorers as they travel deeper into space. The International Space Station will serve as a testbed for the telemedicine technologies to enable future missions as well as improve the quality of healthcare delivery on Earth.

  5. Influence of children pedestrian behaviour on pedestrian space usage

    Science.gov (United States)

    Makalew, F. P.; Adisasmita, S. A.; Wunas, S.; Hamid, S.

    2017-11-01

    School children pedestrian behaviour can be seen along their journey to and from school. Pedestrian spaces used by children are places available in urban and rural areas including streets with and without pedestrian pathways. Samples data are collected from 23 elementary schools in urban and rural areas in North Sulawesi, Indonesia in the form of video records and photos taken. The aim of this research is to analyse children pedestrian behaviour and its influence on the space usage on pedestrian areas. Method of analysis is a comparative study on urban and rural areas. Results of this research are types of behaviour, factors that influence the behaviour, physical condition of pedestrian areas and space usage by children. The behaviours are duck-line walking, running, playing, walking backward and walking with bare foot in which running is the main behaviour. These behaviours are influenced by factors including following friends and responding to acts. There are similarities and differences between pedestrian space usage in urban and rural areas. Space use by children pedestrian demonstrates the way pedestrian areas should be planned. Space usage by children pedestrian indicates that there is a need of evaluation of the space available considering pedestrian children behaviour.

  6. Ray space 'Riccati' evolution and geometric phases for N-level ...

    Indian Academy of Sciences (India)

    evolution of an N-level quantum system to the various coset spaces and Grassmanian ... glement in the context of quantum information and quantum computation [1]. Per- ... the base manifold of a fiber bundle, the total space being SU(N).

  7. Technology for Space Station Evolution. Volume 3: EVA/Manned Systems/Fluid Management System

    Science.gov (United States)

    1990-01-01

    NASA's Office of Aeronautics and Space Technology (OAST) conducted a workshop on technology for space station evolution 16-19 Jan. 1990 in Dallas, Texas. The purpose of this workshop was to collect and clarify Space Station Freedom technology requirements for evolution and to describe technologies that can potentially fill those requirements. These proceedings are organized into an Executive Summary and Overview and five volumes containing the Technology Discipline Presentations. Volume 3 consists of the technology discipline sections for Extravehicular Activity/Manned Systems and the Fluid Management System. For each technology discipline, there is a Level 3 subsystem description, along with the papers.

  8. Evolution of space dependent growth in the teleost Astyanax mexicanus.

    Directory of Open Access Journals (Sweden)

    Natalya D Gallo

    Full Text Available The relationship between growth rate and environmental space is an unresolved issue in teleosts. While it is known from aquaculture studies that stocking density has a negative relationship to growth, the underlying mechanisms have not been elucidated, primarily because the growth rate of populations rather than individual fish were the subject of all previous studies. Here we investigate this problem in the teleost Astyanax mexicanus, which consists of a sighted surface-dwelling form (surface fish and several blind cave-dwelling (cavefish forms. Surface fish and cavefish are distinguished by living in spatially contrasting environments and therefore are excellent models to study the effects of environmental size on growth. Multiple controlled growth experiments with individual fish raised in confined or unconfined spaces showed that environmental size has a major impact on growth rate in surface fish, a trait we have termed space dependent growth (SDG. In contrast, SDG has regressed to different degrees in the Pachón and Tinaja populations of cavefish. Mating experiments between surface and Pachón cavefish show that SDG is inherited as a dominant trait and is controlled by multiple genetic factors. Despite its regression in blind cavefish, SDG is not affected when sighted surface fish are raised in darkness, indicating that vision is not required to perceive and react to environmental space. Analysis of plasma cortisol levels showed that an elevation above basal levels occurred soon after surface fish were exposed to confined space. This initial cortisol peak was absent in Pachón cavefish, suggesting that the effects of confined space on growth may be mediated partly through a stress response. We conclude that Astyanax reacts to confined spaces by exhibiting SDG, which has a genetic component and shows evolutionary regression during adaptation of cavefish to confined environments.

  9. The evolution of space curves by curvature and torsion

    International Nuclear Information System (INIS)

    Richardson, G; King, J R

    2002-01-01

    We apply Lie group based similarity methods to the study of a new, and widely relevant, class of objects, namely motions of a space curve. In particular, we consider the motion of a curve evolving with a curvature κ and torsion τ dependent velocity law. We systematically derive the Lie point symmetries of all such laws of motion and use these to catalogue all their possible similarity reductions. This calculation reveals special classes of law with high degrees of symmetry (and a correspondingly large number of similarity reductions). Of particular note is one class which is invariant under general linear transformations in space. This has potential applications in pattern and signal recognition

  10. Space distribution of extragalactic sources - Cosmology versus evolution

    International Nuclear Information System (INIS)

    Cavaliere, A.; Maccacaro, T.

    1990-01-01

    Alternative cosmologies have been recurrently invoked to explain in terms of global spacetime structure the apparent large increase, with increasing redshift, in the average luminosity of active galactic nuclei. These models interestingly seek to avoid the complexities of the canonical interpretation in terms of intrinsic population evolutions in a Friedmann universe. However, a problem of consistency for these cosmologies is pointed out, since they have to include also other classes of extragalactic sources, such as clusters of galaxies and BL Lac objects, for which there is preliminary evidence of a different behavior. 40 refs

  11. Teaching Evolution: The Blog as a Liminal Space

    Science.gov (United States)

    Akkaraju, Shylaja; Wolf, Alexander

    2016-01-01

    A "threshold concept" is a challenging concept that acts as a doorway leading to deeper understanding and a dramatic shift in perception. A learner that is involved in grasping a threshold concept is said to be undergoing a threshold experience within a "liminal space" or learning environment. We used the blog as a liminal…

  12. Space Weathering Evolution on Airless Bodies - Laboratory Simulations with Olivine

    Czech Academy of Sciences Publication Activity Database

    Kohout, Tomáš; Čuda, J.; Bradley, T.; Britt, D.; Filip, J.; Tuček, J.; Malina, O.; Kašlík, J.; Šišková, K.; Zbořil, R.

    2013-01-01

    Roč. 45, č. 9 (2013), s. 25-26 ISSN 0002-7537. [Annual meeting of the Division for Planetary Sciences of the American Astronomical Society /45./. 06.10.2013-11.10.2013, Denver] Institutional support: RVO:67985831 Keywords : space weathering * asteroid * Moon * olivine Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics http://aas.org/files/resources/dps_abstract_book.pdf

  13. Revisiting Robustness and Evolvability: Evolution in Weighted Genotype Spaces

    Science.gov (United States)

    Partha, Raghavendran; Raman, Karthik

    2014-01-01

    Robustness and evolvability are highly intertwined properties of biological systems. The relationship between these properties determines how biological systems are able to withstand mutations and show variation in response to them. Computational studies have explored the relationship between these two properties using neutral networks of RNA sequences (genotype) and their secondary structures (phenotype) as a model system. However, these studies have assumed every mutation to a sequence to be equally likely; the differences in the likelihood of the occurrence of various mutations, and the consequence of probabilistic nature of the mutations in such a system have previously been ignored. Associating probabilities to mutations essentially results in the weighting of genotype space. We here perform a comparative analysis of weighted and unweighted neutral networks of RNA sequences, and subsequently explore the relationship between robustness and evolvability. We show that assuming an equal likelihood for all mutations (as in an unweighted network), underestimates robustness and overestimates evolvability of a system. In spite of discarding this assumption, we observe that a negative correlation between sequence (genotype) robustness and sequence evolvability persists, and also that structure (phenotype) robustness promotes structure evolvability, as observed in earlier studies using unweighted networks. We also study the effects of base composition bias on robustness and evolvability. Particularly, we explore the association between robustness and evolvability in a sequence space that is AU-rich – sequences with an AU content of 80% or higher, compared to a normal (unbiased) sequence space. We find that evolvability of both sequences and structures in an AU-rich space is lesser compared to the normal space, and robustness higher. We also observe that AU-rich populations evolving on neutral networks of phenotypes, can access less phenotypic variation compared to

  14. Influence of dynamic topography on landscape evolution and passive continental margin stratigraphy

    Science.gov (United States)

    Ding, Xuesong; Salles, Tristan; Flament, Nicolas; Rey, Patrice

    2017-04-01

    Quantifying the interaction between surface processes and tectonics/deep Earth processes is one important aspect of landscape evolution modelling. Both observations and results from numerical modelling indicate that dynamic topography - a surface expression of time-varying mantle convection - plays a significant role in shaping landscape through geological time. Recent research suggests that dynamic topography also has non-negligible effects on stratigraphic architecture by modifying accommodation space available for sedimentation. In addition, dynamic topography influences the sediment supply to continental margins. We use Badlands to investigate the evolution of a continental-scale landscape in response to transient dynamic uplift or subsidence, and to model the stratigraphic development on passive continental margins in response to sea-level change, thermal subsidence and dynamic topography. We consider a circularly symmetric landscape consisting of a plateau surrounded by a gently sloping continental plain and a continental margin, and a linear wave of dynamic topography. We analyze the evolution of river catchments, of longitudinal river profiles and of the χ values to evaluate the dynamic response of drainage systems to dynamic topography. We calculate the amount of cumulative erosion and deposition, and sediment flux at shoreline position, as a function of precipitation rate and erodibility coefficient. We compute the stratal stacking pattern and Wheeler diagram on vertical cross-sections at the continental margin. Our results indicate that dynamic topography 1) has a considerable influence on drainage reorganization; 2) contributes to shoreline migration and the distribution of depositional packages by modifying the accommodation space; 3) affects sediment supply to the continental margin. Transient dynamic topography contributes to the migration of drainage divides and to the migration of the mainstream in a drainage basin. The dynamic uplift

  15. Surface water assessment on the influence of space distribution on ...

    African Journals Online (AJOL)

    In this work, the influence of space distribution on physico-chemical parameters of refinery effluent discharge has been studied, using treated effluent water discharged from the Port Harcourt Refinery Company (PHRC) into the Ekerekana Creek in Okrika as reference. Samples were collected at surface level from the ...

  16. Space platforms - A cost effective evolution of Spacelab operation

    Science.gov (United States)

    Stofan, A. J.

    1981-01-01

    The capabilities added to the Shuttle/Spacelab configuration by the addition of the Power Extension Package (PEP), the Power System (PS), and the Science and Applications Space Platforms (SASP) are reviewed with an emphasis on SASP. SASP are intended for placement in orbit by the Shuttle to test new instruments and systems, for clustering of instrumentation, and for servicing, refurbishment, repair, or augmentation by the Shuttle. The PEP permits extended stays in orbit (30 days), and the PS is an orbital solar array and energy storage system acting as a free flying spacecraft. The Shuttle can deliver payloads to the PS or attach to it for extension of the Spacelab operations. Applications of SASP for long term space-based biological experiments are outlined, and the fact that SASP do not increase the required Shuttle in-orbit time is stressed.

  17. Sexual and Natural Selection Both Influence Male Genital Evolution

    OpenAIRE

    House, Clarissa M.; Lewis, Zenobia; Hodgson, Dave J.; Wedell, Nina; Sharma, Manmohan D.; Hunt, John; Hosken, David J.

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on ...

  18. CoCoNuT: General relativistic hydrodynamics code with dynamical space-time evolution

    Science.gov (United States)

    Dimmelmeier, Harald; Novak, Jérôme; Cerdá-Durán, Pablo

    2012-02-01

    CoCoNuT is a general relativistic hydrodynamics code with dynamical space-time evolution. The main aim of this numerical code is the study of several astrophysical scenarios in which general relativity can play an important role, namely the collapse of rapidly rotating stellar cores and the evolution of isolated neutron stars. The code has two flavors: CoCoA, the axisymmetric (2D) magnetized version, and CoCoNuT, the 3D non-magnetized version.

  19. Impact of time and space evolution of ion tracks in nonvolatile memory cells approaching nanoscale

    International Nuclear Information System (INIS)

    Cellere, G.; Paccagnella, A.; Murat, M.; Barak, J.; Akkerman, A.; Harboe-Sorensen, R.; Virtanen, A.; Visconti, A.; Bonanomi, M.

    2010-01-01

    Swift heavy ions impacting on matter lose energy through the creation of dense tracks of charges. The study of the space and time evolution of energy exchange allows understanding the single event effects behavior in advanced microelectronic devices. In particular, the shrinking of minimum feature size of most advanced memory devices makes them very interesting test vehicles to study these effects since the device and the track dimensions are comparable; hence, measured effects are directly correlated with the time and space evolution of the energy release. In this work we are studying the time and space evolution of ion tracks by using advanced non volatile memories and Monte Carlo simulations. Experimental results are very well explained by the theoretical calculations.

  20. Space-time evolution of electron cascades in diamond

    International Nuclear Information System (INIS)

    Ziaja, Beata; Szoeke, Abraham; Spoel, David van der; Hajdu, Janos

    2002-01-01

    The impact of a primary electron initiates a cascade of secondary electrons in solids, and these cascades play a significant role in the dynamics of ionization. Here we describe model calculations to follow the spatiotemporal evolution of secondary electron cascades in diamond. The band structure of the insulator has been explicitly incorporated into the calculations as it affects ionizations from the valence band. A Monte Carlo model was constructed to describe the path of electrons following the impact of a single electron of energy E∼250 eV. This energy is similar to the energy of an Auger electron from carbon. Two limiting cases were considered: the case in which electrons transmit energy to the lattice, and the case where no such energy transfer is permitted. The results show the evolution of the secondary electron cascades in terms of the number of electrons liberated, the spatial distribution of these electrons, and the energy distribution among the electrons as a function of time. The predicted ionization rates (∼5-13 electrons in 100 fs) lie within the limits given by experiments and phenomenological models. Calculation of the local electron density and the corresponding Debye length shows that the latter is systematically larger than the radius of the electron cloud, and it increases exponentially with the radial size of the cascade. This means that the long-range Coulomb field is not shielded within this cloud, and the electron gas generated does not represent a plasma in a single impact cascade triggered by an electron of E∼250 eV energy. This is important as it justifies the independent-electron approximation used in the model. At 1 fs, the (average) spatial distribution of secondary electrons is anisotropic with the electron cloud elongated in the direction of the primary impact. The maximal radius of the cascade is about 50 A at this time. At 10 fs the cascade has a maximal radius of ∼70 A, and is already dominated by low-energy electrons

  1. Evolution of repetitive explosive instabilities in space and time

    International Nuclear Information System (INIS)

    Wilhelmsson, H.

    1984-01-01

    A nonlinear rate equation describing nonlinear, explosive type interaction of waves in plasmas is studied, assuming that amplitude saturation occurs due to nonlinear frequency shifts. Emphasis is put on the space dependence of the solution caused by the assumption of a given initial amplitude distribution in space. An analysis is given of the problem of repetitive peaks governed by the nonlinear rate equation for the time development of the amplitudes of plasma waves and by a Lorentzian shape distribution of the initial amplitudes. For the one-dimensional case, the peaks developed by explosive instability move in the direction of lower initial amplitude values, and the speed and the repetition rate of the peaks are determined. The possible forms of equilibria for the nonlinear rate equation in the explosive case are also studied, including, in addition to the quadratic nonlinearity, diffusion and linear damping effects. A solution to the nonlinear rate equation including diffusion is also given for the case where the quadratic nonlinearity represents recombination. (Auth.)

  2. Space-time evolution of cataclasis in carbonate fault zones

    Science.gov (United States)

    Ferraro, Francesco; Grieco, Donato Stefano; Agosta, Fabrizio; Prosser, Giacomo

    2018-05-01

    The present contribution focuses on the micro-mechanisms associated to cataclasis of both calcite- and dolomite-rich fault rocks. This work combines field and laboratory data of carbonate fault cores currently exposed in central and southern Italy. By first deciphering the main fault rock textures, their spatial distribution, crosscutting relationships and multi-scale dimensional properties, the relative timing of Intragranular Extensional Fracturing (IEF), chipping, and localized shear is inferred. IEF was predominant within already fractured carbonates, forming coarse and angular rock fragments, and likely lasted for a longer period within the dolomitic fault rocks. Chipping occurred in both lithologies, and was activated by grain rolling forming minute, sub-rounded survivor grains embedded in a powder-like carbonate matrix. The largest fault zones, which crosscut either limestones or dolostones, were subjected to localized shear and, eventually, to flash temperature increase which caused thermal decomposition of calcite within narrow (cm-thick) slip zones. Results are organized in a synoptic panel including the main dimensional properties of survivor grains. Finally, a conceptual model of the time-dependent evolution of cataclastic deformation in carbonate rocks is proposed.

  3. Evolution of axis ratios from phase space dynamics of triaxial collapse

    Science.gov (United States)

    Nadkarni-Ghosh, Sharvari; Arya, Bhaskar

    2018-04-01

    We investigate the evolution of axis ratios of triaxial haloes using the phase space description of triaxial collapse. In this formulation, the evolution of the triaxial ellipsoid is described in terms of the dynamics of eigenvalues of three important tensors: the Hessian of the gravitational potential, the tensor of velocity derivatives, and the deformation tensor. The eigenvalues of the deformation tensor are directly related to the parameters that describe triaxiality, namely, the minor-to-major and intermediate-to-major axes ratios (s and q) and the triaxiality parameter T. Using the phase space equations, we evolve the eigenvalues and examine the evolution of the probability distribution function (PDF) of the axes ratios as a function of mass scale and redshift for Gaussian initial conditions. We find that the ellipticity and prolateness increase with decreasing mass scale and decreasing redshift. These trends agree with previous analytic studies but differ from numerical simulations. However, the PDF of the scaled parameter {\\tilde{q}} = (q-s)/(1-s) follows a universal distribution over two decades in mass range and redshifts which is in qualitative agreement with the universality for conditional PDF reported in simulations. We further show using the phase space dynamics that, in fact, {\\tilde{q}} is a phase space invariant and is conserved individually for each halo. These results demonstrate that the phase space analysis is a useful tool that provides a different perspective on the evolution of perturbations and can be applied to more sophisticated models in the future.

  4. AN/FPS-108 COBRA DANE Space Surveillance Mission Evolution

    Science.gov (United States)

    Chorman, P.; Boggs, J.

    2013-09-01

    It has been ten years since the COBRA DANE radar was restored to continuous full power operations in a more dedicated role of space debris tracking. Over this time, the satellite catalog population has grown and the overall average RCS value of cataloged objects has decreased dramatically, due to a combination of breakups and collisions together with the increased sensitivity offered by COBRA DANE's support to the network. This shift in catalog composition places new challenges on COBRA DANE and other debris tracking radars (PARCS and Eglin/FPS-85) to consistently track the ever-increasing number of small objects. Space Surveillance Network radars now operate at the limits of their detection performance, tracking several thousand new objects in a size category that only the most powerful and sensitive radars can observe (i.e., COBRA DANE's inherent Spacetrack mission software functionality remained better tuned for its original support role against the larger (known) orbital objects than for its more modern role in acquiring and reporting small debris in an appreciable number -- that is, until now. Several newly-identified software changes offer promise of significantly increased data yield that will make COBRA DANE an even more important asset for this evolving mission. In the course of assisting JSpOC, AFSPC, and USSTRATCOM with the ongoing challenges of lost satellite management, it was discovered that the radar's performance is being artificially restricted by mission software, rather than by the system's overall architectural design (power-aperture envelope and radar resources). This paper captures specific opportunities to improve COBRA DANE's Spacetrack mission performance, several of which are currently implemented and slated to become operational with the next two software releases. With one of the more prominent enhancements, COBRA DANE will be capable of autonomously 'fence tasking' all newly acquired small objects. Under the current operating paradigm

  5. Controllability for Semilinear Functional and Neutral Functional Evolution Equations with Infinite Delay in Frechet Spaces

    International Nuclear Information System (INIS)

    Agarwal, Ravi P.; Baghli, Selma; Benchohra, Mouffak

    2009-01-01

    The controllability of mild solutions defined on the semi-infinite positive real interval for two classes of first order semilinear functional and neutral functional differential evolution equations with infinite delay is studied in this paper. Our results are obtained using a recent nonlinear alternative due to Avramescu for sum of compact and contraction operators in Frechet spaces, combined with the semigroup theory

  6. On a nonlinear integrodifferential evolution inclusion with nonlocal initial conditions in Banach spaces

    Directory of Open Access Journals (Sweden)

    Zuomao Yan

    2012-01-01

    Full Text Available In this paper, we discuss the existence results for a class of nnlinear integrodifferential evolution inclusions with nonlocal initial conditions in Banach spaces. Our results are based on a fixed point theorem for condensing maps due to Martelli and the resolvent operators combined with approximation techniques.

  7. Considering the Influence of Nonadaptive Evolution on Primate Color Vision.

    Directory of Open Access Journals (Sweden)

    Rachel L Jacobs

    Full Text Available Color vision in primates is variable across species, and it represents a rare trait in which the genetic mechanisms underlying phenotypic variation are fairly well-understood. Research on primate color vision has largely focused on adaptive explanations for observed variation, but it remains unclear why some species have trichromatic or polymorphic color vision while others are red-green color blind. Lemurs, in particular, are highly variable. While some species are polymorphic, many closely-related species are strictly dichromatic. We provide the first characterization of color vision in a wild population of red-bellied lemurs (Eulemur rubriventer, Ranomafana National Park, Madagascar with a sample size (87 individuals; NX chromosomes = 134 large enough to detect even rare variants (0.95 probability of detection at ≥ 3% frequency. By sequencing exon 5 of the X-linked opsin gene we identified opsin spectral sensitivity based on known diagnostic sites and found this population to be dichromatic and monomorphic for a long wavelength allele. Apparent fixation of this long allele is in contrast to previously published accounts of Eulemur species, which exhibit either polymorphic color vision or only the medium wavelength opsin. This unexpected result may represent loss of color vision variation, which could occur through selective processes and/or genetic drift (e.g., genetic bottleneck. To indirectly assess the latter scenario, we genotyped 55 adult red-bellied lemurs at seven variable microsatellite loci and used heterozygosity excess and M-ratio tests to assess if this population may have experienced a recent genetic bottleneck. Results of heterozygosity excess but not M-ratio tests suggest a bottleneck might have occurred in this red-bellied lemur population. Therefore, while selection may also play a role, the unique color vision observed in this population might have been influenced by a recent genetic bottleneck. These results emphasize the

  8. Space for action: How practitioners influence environmental assessment

    Energy Technology Data Exchange (ETDEWEB)

    Kågström, Mari, E-mail: mari.kagstrom@slu.se [Department of Urban and Rural Development, Swedish University of Agricultural Sciences (Sweden); Richardson, Tim, E-mail: tim.richardson@nmbu.no [Department of Landscape Architecture and Spatial Planning, Norwegian University of Life Sciences, Frederik A Dahls vei 15, KA-bygningen, Ås (Norway)

    2015-09-15

    Highlights: • The concept of ‘space for action’ offers an important new lens on EA practice. • Focuses on the relation between practitioner's understanding and their actions • Environmental assessment practice is decisively shaped by practitioners. • Practitioners may underestimate their potential to make a difference. • Contributes to understanding change in the environmental assessment field. This article contributes to understanding of how change occurs in the field of environmental assessment (EA). It argues that the integration of new issues in EA, such as human health, is significantly influenced by how practitioners' understandings shape their actions, and by what happens when those, possibly different, interpretations of appropriate action are acted out. The concept of space for action is developed as a means of investigating this relation between understanding and action. Frame theory is also used, to develop a sharper focus on how ‘potential spaces for action’ are created, what these imply for (individuals') preferred choices and actions in certain situations, and what happens in practice when these are acted out and ‘actual spaces for action’ are created. This novel approach is then applied in a Swedish case study of transport planning. The analysis reveals the important work done by practitioners, revealing just how EA practice is decisively shaped by practitioners. Analysis of practice using the lens of spaces for action offers an important new perspective in understanding how the field adapts to new challenges.

  9. Space for action: How practitioners influence environmental assessment

    International Nuclear Information System (INIS)

    Kågström, Mari; Richardson, Tim

    2015-01-01

    Highlights: • The concept of ‘space for action’ offers an important new lens on EA practice. • Focuses on the relation between practitioner's understanding and their actions • Environmental assessment practice is decisively shaped by practitioners. • Practitioners may underestimate their potential to make a difference. • Contributes to understanding change in the environmental assessment field. This article contributes to understanding of how change occurs in the field of environmental assessment (EA). It argues that the integration of new issues in EA, such as human health, is significantly influenced by how practitioners' understandings shape their actions, and by what happens when those, possibly different, interpretations of appropriate action are acted out. The concept of space for action is developed as a means of investigating this relation between understanding and action. Frame theory is also used, to develop a sharper focus on how ‘potential spaces for action’ are created, what these imply for (individuals') preferred choices and actions in certain situations, and what happens in practice when these are acted out and ‘actual spaces for action’ are created. This novel approach is then applied in a Swedish case study of transport planning. The analysis reveals the important work done by practitioners, revealing just how EA practice is decisively shaped by practitioners. Analysis of practice using the lens of spaces for action offers an important new perspective in understanding how the field adapts to new challenges

  10. From stochastic phase-space evolution to brownian motion in collective space

    Energy Technology Data Exchange (ETDEWEB)

    Benhassine, B. (Lab. de Physique Nucleaire/ CNRS et Univ. de Nantes, 44 Nantes (France)); Farine, M. (Lab. de Physique Nucleaire/ CNRS et Univ. de Nantes, 44 Nantes (France) Ecole Navale, Lamveoc-Loulmic, 29 Brest-Naval (France)); Hernandez, E.S. (Dept. de Fisica - Facultad de Ciencias Exactas y Naturales, Univ. de Buenos Aires (Argentina)); Idier, D. (Lab. de Physique Nucleaire/ CNRS et Univ. de Nantes, 44 Nantes (France)); Remaud, B. (Lab. de Physique Nucleaire/ CNRS et Univ. de Nantes, 44 Nantes (France)); Sebille, F. (Lab. de Physique Nucleaire/ CNRS et Univ. de Nantes, 44 Nantes (France))

    1994-01-24

    Within the framework of stochastic transport equations in phase space, we study the dynamics of fluctuations on collective variables in homogeneous fermion systems. The transport coefficients are formally deduced in the relaxation-time approximation and a general method to compute dynamically the dispersions of collective observables is proposed as a set of coupled equations: respectively, the BUU/Landau-Vlasov equation for the average phase-space trajectories and the equations for the averages and dispersions of the observables. Independently, we derive the general covariance matrix of phase-space fluctuations and then by projection, the dispersion on collective variables at equilibrium. Detailed numerical applications of the formalism are given; they show that the dynamics of fluctuations can be extracted from noisy numerical simulations and that the leading parameter for collective fluctuations is the excitation energy, whatever is its degree of thermalization. (orig.)

  11. From stochastic phase-space evolution to brownian motion in collective space

    International Nuclear Information System (INIS)

    Benhassine, B.; Farine, M.; Hernandez, E.S.; Idier, D.; Remaud, B.; Sebille, F.

    1994-01-01

    Within the framework of stochastic transport equations in phase space, we study the dynamics of fluctuations on collective variables in homogeneous fermion systems. The transport coefficients are formally deduced in the relaxation-time approximation and a general method to compute dynamically the dispersions of collective observables is proposed as a set of coupled equations: respectively, the BUU/Landau-Vlasov equation for the average phase-space trajectories and the equations for the averages and dispersions of the observables. Independently, we derive the general covariance matrix of phase-space fluctuations and then by projection, the dispersion on collective variables at equilibrium. Detailed numerical applications of the formalism are given; they show that the dynamics of fluctuations can be extracted from noisy numerical simulations and that the leading parameter for collective fluctuations is the excitation energy, whatever is its degree of thermalization. (orig.)

  12. Landscape evolution space and the relative importance of geomorphic processes and controls

    Science.gov (United States)

    Phillips, Jonathan D.

    2009-08-01

    The concept of landscape evolution space (LES) is introduced as a tool for assessing landscapes and geomorphic systems, intended to be a systematic means for assessing the various factors that contribute to the potential for change in geomorphic systems. The LES conceptual model is based on the energy and mass available to drive and accommodate landscape evolution. An n-dimensional landscape evolution space is defined not only by spatial coordinates, but also by the availability of mass and energy. The LES is thus a space or hypervolume representing the resources available for geomorphic evolution and landscape change. An expression for LES is derived based on elevation, material density, surface area, and inputs of solar, meteoric, and biological energy and mass. Though primarily an heuristic device, the LES model can be used to address concrete problems. Two examples are given. In one, increased surface area due to topographic roughening and dissection of an incised plateau is found to only slightly offset erosional removals of mass in terms of the magnitude of the LES. In the other, sensitivity of coastal plain rivers to several impacts of sea level and climate change is explored. The LES model also leads to the concept of a geomorphological niche, representing the resources available to drive or support a specific process or suite of processes. Considerations of landscape evolution have traditionally focused on the interplay of endogenic vs. exogenic processes, uplift vs. denudation, or soil formation vs. erosion. The LES model explicitly broadens the conceptual framework of landscape evolution beyond the traditional dialectics.

  13. From stochastic phase space evolution to Brownian motion in collective space

    International Nuclear Information System (INIS)

    Benhassine, B.; Farine, M.; Hernandez, E.S.; Idier, D.; Remaud, B.; Sebille, F.

    1993-01-01

    Within the framework of stochastic transport equations in phase space, the dynamics of fluctuations on collective variables in homogeneous fermion systems is studied. The transport coefficients are formally deduced in the relaxation time approximation and a general method to compute dynamically the dispersions of collective observables is proposed as a set of coupled equations. Independently, the general covariance matrix of phase space fluctuations and the dispersion on collective variables at equilibrium are derived. Detailed numerical applications show that dynamics of fluctuations can be extracted from noisy numerical simulations and that the leading parameter for collective fluctuations is the excitation energy whatever is its degree of thermalization. (authors). 16 refs., 12 figs

  14. Inverse scattering solution of non-linear evolution equations in one space dimension: an introduction

    International Nuclear Information System (INIS)

    Alvarez-Estrada, R.F.

    1979-01-01

    A comprehensive review of the inverse scattering solution of certain non-linear evolution equations of physical interest in one space dimension is presented. We explain in some detail the interrelated techniques which allow to linearize exactly the following equations: (1) the Korteweg and de Vries equation; (2) the non-linear Schrodinger equation; (3) the modified Korteweg and de Vries equation; (4) the Sine-Gordon equation. We concentrate in discussing the pairs of linear operators which accomplish such an exact linearization and the solution of the associated initial value problem. The application of the method to other non-linear evolution equations is reviewed very briefly

  15. Three Southern high school biology teachers' perspectives on teaching evolution: Sociocultural influences

    Science.gov (United States)

    Kyzer, Peggy Mckewen

    Organizations in science and science education call for students to have a thorough understanding of the theory of evolution. Yet many high school biology teachers do not teach evolution and/or include creationism in their instruction (National Academy of Science, 1998). Historically, the controversy surrounding evolution has created tension for teachers. This case study explored the sociocultural influences related to teaching evolution in three Southern 10th-grade public high school biology classrooms. It also explored the socially and culturally embedded influences on teachers' instructional goals and personal perspectives toward evolution as well as modification of instruction when evolution is taught. Theoretically framed using symbolic interactionism and sociocultural theory, data were collected between October 2003 and April 2004 and included classroom observations two to three times per week, artifacts, and in-depth interviews of the participating teachers, their science department chairpersons, their students, and a Protestant minister. The classroom teachers were unaware of the focus of the study until after evolution was taught. The analysis used in this study was an inductive, interpretative approach that allowed exploration of the sociocultural influences that affect how teachers teach evolution. The sociocultural influences and the lived experiences of each teacher created a continuum for teaching evolution. One of the participating teachers who was heavily involved in the community and one of its fundamentalist churches elected to avoid teaching evolution. Another participating teacher at the same school integrated the theory of evolution in every unit. The third teacher who taught in another school elected to teach evolution in a superficial manner to avoid conflict. The data revealed that the participating teachers' sociocultural situatedness influenced their decisions and instruction on evolution. The influence of strong religious beliefs within

  16. Response actions influence the categorization of directions in auditory space

    Directory of Open Access Journals (Sweden)

    Marcella de Castro Campos Velten

    2015-08-01

    Full Text Available Spatial region concepts such as front, back, left and right reflect our typical interaction with space, and the corresponding surrounding regions have different statuses in memory. We examined the representation of spatial directions in the auditory space, specifically in how far natural response actions, such as orientation movements towards a sound source, would affect the categorization of egocentric auditory space. While standing in the middle of a circle with 16 loudspeakers, participants were presented acoustic stimuli coming from the loudspeakers in randomized order, and verbally described their directions by using the concept labels front, back, left, right, front-right, front-left, back-right and back-left. Response actions varied in three blocked conditions: 1 facing front, 2 turning the head and upper body to face the stimulus, and 3 turning the head and upper body plus pointing with the hand and outstretched arm towards the stimulus. In addition to a protocol of the verbal utterances, motion capture and video recording generated a detailed corpus for subsequent analysis of the participants’ behavior. Chi-square tests revealed an effect of response condition for directions within the left and right sides. We conclude that movement-based response actions influence the representation of auditory space, especially within the sides’ regions.

  17. Factors which influence Texas biology teachers' decisions to emphasize fundamental concepts of evolution

    Science.gov (United States)

    Bilica, Kimberly Lynn

    The teaching of biological evolution in public science classrooms has been mitigated by a lingering and historic climate of controversy (Skoog, 1984; Skoog, 1979). This controversy has successfully stalled attempts to bring authentic science literacy to the American public (Bybee, 1997). The first encouraging signs of the abatement of this controversy occurred during the early 1990s when several prominent science organizations promoted evolution to its appropriate status as a central and unifying concept in biology (National Science Teachers Association, 1992; National Research Council, 1996; American Association for the Advancement of Science, 1990, 1993). The organizations acknowledged that not only should biological evolution be taught, evolution should stand as one of a select group of essential concepts upon which biology curricula should be built. Bandura's Social Learning theory (Bandura, 1997; Lumpe, Haney, & Czerniak, 2000) and Helms' Model of Identity (Helms, 1998) provide the theoretical basis for this study. Both Bandura and Helms explain the actions of teachers by examining the beliefs and values that influence their decisions. The models distinguish between two types of belief systems: capacity beliefs and context beliefs (Lumpe, et al, 2000; Helms, 1998). Both belief types influence and are influenced by individual actions. In this study, the action to be described is the decision that teachers make about the degree of emphasis on evolution in the classroom. The capacity beliefs that will be examined are teachers' beliefs about their capability to teach evolution. The contextual beliefs in this study are perceptions about students' capabilities to learn evolution, the status of evolution in science, the place of evolution in the biology classroom, the influence of textbooks, time, and community/school values. This study contributes to and extends the knowledge base established by studies of evolution education by exploring the relative amount of

  18. Addressing the Influence of Space Weather on Airline Navigation

    Science.gov (United States)

    Sparks, Lawrence

    2012-01-01

    The advent of satellite-based augmentation systems has made it possible to navigate aircraft safely using radio signals emitted by global navigation satellite systems (GNSS) such as the Global Positioning System. As a signal propagates through the earth's ionosphere, it suffers delay that is proportional to the total electron content encountered along the raypath. Since the magnitude of this total electron content is strongly influenced by space weather, the safety and reliability of GNSS for airline navigation requires continual monitoring of the state of the ionosphere and calibration of ionospheric delay. This paper examines the impact of space weather on GNSS-based navigation and provides an overview of how the Wide Area Augmentation System protects its users from positioning error due to ionospheric disturbances

  19. Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe

    International Nuclear Information System (INIS)

    Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Nagashima, Masahiro

    2014-01-01

    Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.

  20. Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe

    Energy Technology Data Exchange (ETDEWEB)

    Enoki, Motohiro [Faculty of Business Administration, Tokyo Keizai University, Kokubunji, Tokyo 185-8502 (Japan); Ishiyama, Tomoaki [Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Kobayashi, Masakazu A. R. [Research Center for Space and Cosmic Evolution, Ehime University, Matsuyama, Ehime 790-8577 (Japan); Nagashima, Masahiro, E-mail: enokimt@tku.ac.jp [Faculty of Education, Nagasaki University, Nagasaki, Nagasaki 852-8521 (Japan)

    2014-10-10

    Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.

  1. Space evolution model and empirical analysis of an urban public transport network

    Science.gov (United States)

    Sui, Yi; Shao, Feng-jing; Sun, Ren-cheng; Li, Shu-jing

    2012-07-01

    This study explores the space evolution of an urban public transport network, using empirical evidence and a simulation model validated on that data. Public transport patterns primarily depend on traffic spatial-distribution, demands of passengers and expected utility of investors. Evolution is an iterative process of satisfying the needs of passengers and investors based on a given traffic spatial-distribution. The temporal change of urban public transport network is evaluated both using topological measures and spatial ones. The simulation model is validated using empirical data from nine big cities in China. Statistical analyses on topological and spatial attributes suggest that an evolution network with traffic demands characterized by power-law numerical values which distribute in a mode of concentric circles tallies well with these nine cities.

  2. Reservoir Space Evolution of Volcanic Rocks in Deep Songliao Basin, China

    Science.gov (United States)

    Zheng, M.; Wu, X.; Zheng, M.; HU, J.; Wang, S.

    2015-12-01

    Recent years, large amount of natural gas has been discovered in volcanic rock of Lower Crataceous of Songliao basin. Volcanic reservoirs have become one of the important target reservoir types of eastern basin of China. In order to study the volcanic reservoirs, we need to know the main factors controlling the reservoir space. By careful obsercation on volcanic drilling core, casting thin sections and statistical analysis of petrophysical properties of volcanic reservoir in Songliao basin, it can be suggested that the igneous rock reservoir in Yingcheng formation of Lower Crataceous is composed of different rock types, such ad rohylite, rohylitic crystal tuff, autoclastic brecciation lava and so on. There are different reservoirs storage space in in various lithological igneous rocks, but they are mainly composed of primary stoma, secondary solution pores and fractures.The evolution of storage space can be divided into 3 stage: the pramary reservoir space,exogenic leaching process and burial diagenesis.During the evolution process, the reservoir space is effected by secondary minerals, tectonic movement and volcanic hydrothermal solution. The pore of volcanic reservoirs can be partially filled by secondary minerals, but also may be dissoluted by other chemical volcanic hydrothermal solution. Therefore, the favorable places for better-quality volcanic reservoirs are the near-crater facies of vocanic apparatus and dissolution zones on the high position of paleo-structures.

  3. Influence of urban waterfront appearance on public space functions

    Directory of Open Access Journals (Sweden)

    Iva Hradilová

    2012-01-01

    Full Text Available Although the issue of urban waterfront is not entirely new, it still represents a very vivid topic. Urban waterfronts have for long been standing in the forefront of many architects and organizations, who are aware of their value and the potential a watercourse carries within the urban interior. A watercourse is an interconnecting element between the urban development and the surrounding countryside and urban waterfronts are the intermediaries of communication. It is exactly in their area where the city - a purely human product with an inner structure and order defined by humans - meets the element of water, which is a purely natural component.What influences the urban structure most is, however, the presence of water in its very basic form i.e. in the form of a river. Its significance and effect on the public space and the inner relations within the body of the settlement vary with the size and the width of the flow, character of the waterfront, architectural layout of the riverbanks and its current utilization. Urban river works as a communication element which meets with the natural features. It seems to be unnatural to define a waterfront space like mono-functional site. This space denies the very essence of the waterfront and the city’s inhabitants appear as unattractive. In this case the very attractive element of water is unable to urban residents to attract together. In general, the quality of the public space is determined by the degree of its utilization by a wider group of inhabitants. It is the inhabitants themselves who imprints the concept of a public space to empty urban spaces.The present form of urban waterfronts is a result of the historical development, attitude and mental state of the society. The architectural appearance of not only the waterfront but also all public spaces is a reflection of the current social values. It gives evidence about the character of the society, the present economic system, the state and thinking

  4. Possible space weather influence on the Earth wheat prices

    Science.gov (United States)

    Pustil'Nik, L.; Yom Din, G.; Dorman, L.

    We present development of our study of possible influence of space weather modulated by cycle of solar activity on the price bursts in the Earth markets In our previous works 1 2 we showed that correspondent response may have place in the specific locations characterized by a high sensitivity of the weather cloudiness in particular to cosmic ray variation b risk zone agriculture c isolated wheat market with limited external supply of agriculture production We showed that in this situation we may wait specific price burst reaction on unfavorable phase of solar activity and space weather what lead to corresponding abnormalities in the local weather and next crop failure We showed that main types of manifestation of this connection are a Distribution of intervals between price bursts must be like to the distribution of intervals between correspondent extremes of solar activity minimums or maximums b price asymmetry between opposite states of solar activity price in the one type of activity state is systematically higher then in the opposite one We showed in our previous publications that this influence in interval distribution is detected with high reliability in Mediaeval England 1250-1700 both for wheat prices and price of consumables basket We showed that for period of Maunder Minimum price asymmetry of wheat prices observed all prices in minimum state of solar activity was higher the prices in the next maximum state We showed later that this price asymmetry had place in 20-th century in USA durum prices too In

  5. Monitoring microstructural evolution in-situ during cyclic deformation by high resolution reciprocal space mapping

    DEFF Research Database (Denmark)

    Diederichs, Annika Martina; Thiel, Felix; Fischer, Torben

    2017-01-01

    The recently developed synchrotron technique High Resolution Reciprocal Space Mapping (HRRSM) is used to characterize the deformation structures evolving during cyclic deformation of commercially pure, polycrystalline aluminium AA1050. Insight into the structural reorganization within single grains...... is gained by in-situ monitoring of the microstructural evolution during cyclic deformation. By HRRSM, a large number of individual subgrains can be resolved within individual grains in the bulk of polycrystalline specimens and their fate, their individual orientation and elastic stresses, tracked during...

  6. Determining Selection across Heterogeneous Landscapes: A Perturbation-Based Method and Its Application to Modeling Evolution in Space.

    Science.gov (United States)

    Wickman, Jonas; Diehl, Sebastian; Blasius, Bernd; Klausmeier, Christopher A; Ryabov, Alexey B; Brännström, Åke

    2017-04-01

    Spatial structure can decisively influence the way evolutionary processes unfold. To date, several methods have been used to study evolution in spatial systems, including population genetics, quantitative genetics, moment-closure approximations, and individual-based models. Here we extend the study of spatial evolutionary dynamics to eco-evolutionary models based on reaction-diffusion equations and adaptive dynamics. Specifically, we derive expressions for the strength of directional and stabilizing/disruptive selection that apply both in continuous space and to metacommunities with symmetrical dispersal between patches. For directional selection on a quantitative trait, this yields a way to integrate local directional selection across space and determine whether the trait value will increase or decrease. The robustness of this prediction is validated against quantitative genetics. For stabilizing/disruptive selection, we show that spatial heterogeneity always contributes to disruptive selection and hence always promotes evolutionary branching. The expression for directional selection is numerically very efficient and hence lends itself to simulation studies of evolutionary community assembly. We illustrate the application and utility of the expressions for this purpose with two examples of the evolution of resource utilization. Finally, we outline the domain of applicability of reaction-diffusion equations as a modeling framework and discuss their limitations.

  7. The Influence of Free Space Environment in the Mission Life Cycle: Material Selection

    Science.gov (United States)

    Edwards, David L.; Burns, Howard D.; de Groh, Kim K.

    2014-01-01

    The natural space environment has a great influence on the ability of space systems to perform according to mission design specification. Understanding the natural space environment and its influence on space system performance is critical to the concept formulation, design, development, and operation of space systems. Compatibility with the natural space environment is a primary factor in determining the functional lifetime of the space system. Space systems being designed and developed today are growing in complexity. In many instances, the increased complexity also increases its sensitivity to space environmental effects. Sensitivities to the natural space environment can be tempered through appropriate design measures, material selection, ground processing, mitigation strategies, and/or the acceptance of known risks. The design engineer must understand the effects of the natural space environment on the space system and its components. This paper will discuss the influence of the natural space environment in the mission life cycle with a specific focus on the role of material selection.

  8. Space Transportation System Availability Requirements and Its Influencing Attributes Relationships

    Science.gov (United States)

    Rhodes, Russell E.; Adams, Timothy C.; McCleskey, Carey M.

    2008-01-01

    It is important that engineering and management accept the need for an availability requirement that is derived with its influencing attributes. It is the intent of this paper to provide the visibility of relationships of these major attribute drivers (variables) to each other and the resultant system inherent availability. Also important to provide bounds of the variables providing engineering the insight required to control the system's engineering solution, e.g., these influencing attributes become design requirements also. These variables will drive the need to provide integration of similar discipline functions or technology selection to allow control of the total parts count. The relationship of selecting a reliability requirement will place a constraint on parts count to achieve a given availability requirement or if allowed to increase the parts count will drive the system reliability requirement higher. They also provide the understanding for the relationship of mean repair time (or mean down time) to maintainability, e.g., accessibility for repair, and both the mean time between failure, e.g., reliability of hardware and availability. The concerns and importance of achieving a strong availability requirement is driven by the need for affordability, the choice of using the two launch solution for the single space application, or the need to control the spare parts count needed to support the long stay in either orbit or on the surface of the moon. Understanding the requirements before starting the architectural design concept will avoid considerable time and money required to iterate the design to meet the redesign and assessment process required to achieve the results required of the customer's space transportation system. In fact the impact to the schedule to being able to deliver the system that meets the customer's needs, goals, and objectives may cause the customer to compromise his desired operational goal and objectives resulting in considerable

  9. Space Transportation System Availability Requirement and Its Influencing Attributes Relationships

    Science.gov (United States)

    Rhodes, Russel E.; Adams, Timothy C.; McCleskey, Carey M.

    2008-01-01

    It is important that engineering and management accept the need for an availability requirement that is derived with its influencing attributes. It is the intent of this paper to provide the visibility of relationships of these major attribute drivers (variables) to each other and the resultant system inherent availability. Also important to provide bounds of the variables providing engineering the insight required to control the system's engineering solution, e.g., these influencing attributes become design requirements also. These variables will drive the need to provide integration of similar discipline functions or technology selection to allow control of the total parts count. The relationship of selecting a reliability requirement will place a constraint on parts count to achieve a given availability requirement or if allowed to increase the parts count will drive the system reliability requirement higher. They also provide the understanding for the relationship of mean repair time (or mean down time) to maintainability, e.g., accessibility for repair, and both the mean time between failure, e.g., reliability of hardware and availability. The concerns and importance of achieving a strong availability requirement is driven by the need for affordability, the choice of using the two launch solution for the single space application, or the need to control the spare parts count needed to support the long stay in either orbit or on the surface of the moon. Understanding the requirements before starting the architectural design concept will avoid considerable time and money required to iterate the design to meet the redesign and assessment process required to achieve the results required of the customer's space transportation system. In fact the impact to the schedule to being able to deliver the system that meets the customer's needs, goals, and objectives may cause the customer to compromise his desired operational goal and objectives resulting in considerable

  10. Optimal trajectory planning of free-floating space manipulator using differential evolution algorithm

    Science.gov (United States)

    Wang, Mingming; Luo, Jianjun; Fang, Jing; Yuan, Jianping

    2018-03-01

    The existence of the path dependent dynamic singularities limits the volume of available workspace of free-floating space robot and induces enormous joint velocities when such singularities are met. In order to overcome this demerit, this paper presents an optimal joint trajectory planning method using forward kinematics equations of free-floating space robot, while joint motion laws are delineated with application of the concept of reaction null-space. Bézier curve, in conjunction with the null-space column vectors, are applied to describe the joint trajectories. Considering the forward kinematics equations of the free-floating space robot, the trajectory planning issue is consequently transferred to an optimization issue while the control points to construct the Bézier curve are the design variables. A constrained differential evolution (DE) scheme with premature handling strategy is implemented to find the optimal solution of the design variables while specific objectives and imposed constraints are satisfied. Differ from traditional methods, we synthesize null-space and specialized curve to provide a novel viewpoint for trajectory planning of free-floating space robot. Simulation results are presented for trajectory planning of 7 degree-of-freedom (DOF) kinematically redundant manipulator mounted on a free-floating spacecraft and demonstrate the feasibility and effectiveness of the proposed method.

  11. Postcopulatory sexual selection influences baculum evolution in primates and carnivores.

    Science.gov (United States)

    Brindle, Matilda; Opie, Christopher

    2016-12-14

    The extreme morphological variability of the baculum across mammals is thought to be the result of sexual selection (particularly, high levels of postcopulatory selection). However, the evolutionary trajectory of the mammalian baculum is little studied and evidence for the adaptive function of the baculum has so far been elusive. Here, we use Markov chain Monte Carlo methods implemented in a Bayesian phylogenetic framework to reconstruct baculum evolution across the mammalian class and investigate the rate of baculum length evolution within the primate order. We then test the effects of testes mass (postcopulatory sexual selection), polygamy, seasonal breeding and intromission duration on the baculum in primates and carnivores. The ancestral mammal did not have a baculum, but both ancestral primates and carnivores did. No relationship was found between testes mass and baculum length in either primates or carnivores. Intromission duration correlated with baculum presence over the course of primate evolution, and prolonged intromission predicts significantly longer bacula in extant primates and carnivores. Both polygamous and seasonal breeding systems predict significantly longer bacula in primates. These results suggest the baculum plays an important role in facilitating reproductive strategies in populations with high levels of postcopulatory sexual selection. © 2016 The Authors.

  12. Evolution of Boolean networks under selection for a robust response to external inputs yields an extensive neutral space

    Science.gov (United States)

    Szejka, Agnes; Drossel, Barbara

    2010-02-01

    We study the evolution of Boolean networks as model systems for gene regulation. Inspired by biological networks, we select simultaneously for robust attractors and for the ability to respond to external inputs by changing the attractor. Mutations change the connections between the nodes and the update functions. In order to investigate the influence of the type of update functions, we perform our simulations with canalizing as well as with threshold functions. We compare the properties of the fitness landscapes that result for different versions of the selection criterion and the update functions. We find that for all studied cases the fitness landscape has a plateau with maximum fitness resulting in the fact that structurally very different networks are able to fulfill the same task and are connected by neutral paths in network (“genotype”) space. We find furthermore a connection between the attractor length and the mutational robustness, and an extremely long memory of the initial evolutionary stage.

  13. Extended space expectation values of position related operators for hydrogen-like quantum system evolutions

    International Nuclear Information System (INIS)

    Kalay, Berfin; Demiralp, Metin

    2014-01-01

    The expectation value definitions over an extended space from the considered Hilbert space of the system under consideration is given in another paper of the second author in this symposium. There, in that paper, the conceptuality rather than specification is emphasized on. This work uses that conceptuality to investigate the time evolutions of the position related operators' expectation values not in its standard meaning but rather in a new version of the definition over not the original Hilbert space but in the space obtained by extensions via introducing the images of the given initial wave packet under the positive integer powers of the system Hamiltonian. These images may not be residing in the same space of the initial wave packet when certain singularities appear in the structure of the system Hamiltonian. This may break down the existence of the integrals in the definitions of the expectation values. The cure is the use of basis functions in the abovementioned extended space and the sandwiching of the target operator whose expectation value is under questioning by an appropriately chosen operator guaranteeing the existence of the relevant integrals. Work specifically focuses on the hydrogen-like quantum systems whose Hamiltonians contain a polar singularity at the origin

  14. INFLUENCE OF THE ENVIRONMENT CHARACTERISTICS ON INDUSTRY SYSTEM EVOLUTION

    Directory of Open Access Journals (Sweden)

    Markov L. S.

    2014-09-01

    Full Text Available On the basis of the constructed evolutionary model in relation to branch of production of steam coals its structural transformation at taking note of various environmental characteristics is considered: endogenous competition, antimonopoly and anti-recessionary regulation. As an indicator of evolution of system it is offered to consider its structural change (Herfindahl-Hirschman index. The executed modeling showed that the speed of evolution of system, more intensive processes of concentration is in direct dependence on a price factor and in inverse relationship from rigidity of criteria of a dominant position. Frequency of transformation of system grows at increase in sensitivity of market price to a ratio of supply and demand and at cancellation of restrictions on the maximum volume, and decreases at liberalization of anti-recessionary regulation. It is shown that actions of antimonopoly and antirecessionary regulation can make sense in the short-term period, but in long-term prospect they lead to braking of development of system.

  15. Particulate pollution in ventilated space: Analysis of influencing factors

    International Nuclear Information System (INIS)

    Zhao Bin; Wu Jun

    2009-01-01

    Particle pollution has been identified to be a major indoor air pollution problem as many epidemiologic evidences have indicated that the particle exposure affects the occupant health. In common practice, mechanical ventilation is introduced to maintain a satisfactory indoor air quality for the occupant, which includes the area of particle control within the space. In order to have an effective control to the indoor particle pollution, it is important to understand the major factors influencing the indoor particle concentration in the breathing zone. This study employs a previously proposed approach to study the particle pollution in a typical ventilation system. The model simultaneously takes into account the interactions between particle transport in ventilation ducts and rooms and particle spatial distribution. It has been proven that an entire ventilation system, including filters, ducts and rooms, can be regarded as a serial of filters in steady-state cases, hence the name 'particle filter group model'. The particle concentration in the breathing zone is calculated under different conditions, and the result is then validated by experimental data. Based on the results, four main factors that affect the particle concentration in the breathing zone are identified, they are fresh air rate, particle filter efficiency, the type of the ventilation duct (roughness) and ventilation modes. Their degrees of influence are analyzed and then the possible measures to improve/control the indoor particle pollution are suggested

  16. Plasma-induced evolution behavior of space-charge-limited current for multiple-needle cathodes

    International Nuclear Information System (INIS)

    Li Limin; Liu Lie; Zhang Jun; Wen Jianchun; Liu Yonggui; Wan Hong

    2009-01-01

    Properties of the plasma and beam flow produced by tufted carbon fiber cathodes in a diode powered by a ∼500 kV, ∼400 ns pulse are investigated. Under electric fields of 230-260 kV cm -1 , the electron current density was in the range 210-280 A cm -2 , and particularly at the diode gap of 20 mm, a maximum beam power density of about 120 MW cm -2 was obtained. It was found that space-charge-limited current exhibited an evolution behavior as the accelerating pulse proceeded. There exists a direct relation between the movement of plasma within the diode and the evolution of space-charge-limited current. Initially in the accelerating pulse, the application of strong electric fields caused the emission sites to explode, forming cathode flares or plasma spots, and in this stage the space-charge-limited current was approximately described by a multiple-needle cathode model. As the pulse proceeded, these plasma spots merged and expanded towards the anode, thus increasing the emission area and shortening the diode gap, and the corresponding space-charge-limited current followed a planar cathode model. Finally, the space-charge-limited current is developed from a unipolar flow into a bipolar flow as a result of the appearance of anode plasma. In spite of the nonuniform distribution of cathode plasma, the cross-sectional uniformity of the extracted electron beam is satisfactory. The plasma expansion within the diode is found to be a major factor in the diode perveance growth and instability. These results show that these types of cathodes can offer promising applications for high-power microwave tubes.

  17. The dimensionality of stellar chemical space using spectra from the Apache Point Observatory Galactic Evolution Experiment

    Science.gov (United States)

    Price-Jones, Natalie; Bovy, Jo

    2018-03-01

    Chemical tagging of stars based on their similar compositions can offer new insights about the star formation and dynamical history of the Milky Way. We investigate the feasibility of identifying groups of stars in chemical space by forgoing the use of model derived abundances in favour of direct analysis of spectra. This facilitates the propagation of measurement uncertainties and does not pre-suppose knowledge of which elements are important for distinguishing stars in chemical space. We use ˜16 000 red giant and red clump H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and perform polynomial fits to remove trends not due to abundance-ratio variations. Using expectation maximized principal component analysis, we find principal components with high signal in the wavelength regions most important for distinguishing between stars. Different subsamples of red giant and red clump stars are all consistent with needing about 10 principal components to accurately model the spectra above the level of the measurement uncertainties. The dimensionality of stellar chemical space that can be investigated in the H band is therefore ≲10. For APOGEE observations with typical signal-to-noise ratios of 100, the number of chemical space cells within which stars cannot be distinguished is approximately 1010±2 × (5 ± 2)n - 10 with n the number of principal components. This high dimensionality and the fine-grained sampling of chemical space are a promising first step towards chemical tagging based on spectra alone.

  18. Influence of particle shape on the microstructure evolution and the mechanical properties of granular materials

    Science.gov (United States)

    Tian, Jianqiu; Liu, Enlong; Jiang, Lian; Jiang, Xiaoqiong; Sun, Yi; Xu, Ran

    2018-06-01

    In order to study the influence of particle shape on the microstructure evolution and the mechanical properties of granular materials, a two-dimensional DEM analysis of samples with three particle shapes, including circular particles, triangular particles, and elongated particles, is proposed here to simulate the direct shear tests of coarse-grained soils. For the numerical test results, analyses are conducted in terms of particle rotations, fabric evolution, and average path length evolution. A modified Rowe's stress-dilatancy equation is also proposed and successfully fitted onto simulation data.

  19. EVOLUTION OF DARK MATTER PHASE-SPACE DENSITY DISTRIBUTIONS IN EQUAL-MASS HALO MERGERS

    International Nuclear Information System (INIS)

    Vass, Ileana M.; Kazanzidis, Stelios; Valluri, Monica; Kravtsov, Andrey V.

    2009-01-01

    We use dissipationless N-body simulations to investigate the evolution of the true coarse-grained phase-space density distribution f(x, v) in equal-mass mergers between dark matter (DM) halos. The halo models are constructed with various asymptotic power-law indices ρ ∝ r -γ ranging from steep cusps to core-like profiles and we employ the phase-space density estimator 'EnBid' developed by Sharma and Steinmetz to compute f(x, v). The adopted force resolution allows robust phase-space density profile estimates in the inner ∼1% of the virial radii of the simulated systems. We confirm that merger events result in a decrease of the coarse-grained phase-space density in accordance with expectations from Mixing Theorems for collisionless systems. We demonstrate that binary mergers between identical DM halos produce remnants that retain excellent memories of the inner slopes and overall shapes of the phase-space density distribution of their progenitors. The robustness of the phase-space density profiles holds for a range of orbital energies, and a variety of encounter configurations including sequences of several consecutive merger events, designed to mimic hierarchical merging, and collisions occurring at different cosmological epochs. If the progenitor halos are constructed with appreciably different asymptotic power-law indices, we find that the inner slope and overall shape of the phase-space density distribution of the remnant are substantially closer to that of the initial system with the steepest central density cusp. These results explicitly demonstrate that mixing is incomplete in equal-mass mergers between DM halos, as it does not erase memory of the progenitor properties. Our results also confirm the recent analytical predictions of Dehnen regarding the preservation of merging self-gravitating central density cusps.

  20. Use of space photographs in deciphering the origin and evolution of the desert

    International Nuclear Information System (INIS)

    El-Baz, F.

    1989-01-01

    Space photographs provide a very useful tool to study deserts and semiarid land because of their coverage and the amount of data they portray about vegetation-free terrain. This is a welcome contribution because we do not understand the desert as we do other types of terrain. Results of wind action, erosion and deposition are clearly portrayed in images obtained from spacecraft. They are indications of the state of the environment and should be studied well in all cases where economic development projects are instituted in deserts and semiarid lands. Furthermore, the history of evolution of the arid landscape in space and time must be considered in order to be able to use more of the desert for the benefit of mankind. (author). 33 refs, 14 figs

  1. The Evolution of the Rendezvous Profile During the Space Shuttle Program

    Science.gov (United States)

    Summa, William R.

    2010-01-01

    The rendezvous and proximity operations approach design techniques for space shuttle missions has changed significantly during the life of the program in response to new requirements that were not part of the original mission design. The flexibility of the shuttle onboard systems design and the mission planning process has allowed the program to meet these requirements. The design of the space shuttle and the shift from docking to grappling with a robotic ann prevented use of legacy Apollo rendezvous techniques. Over the life of the shuttle program the rendezvous profile has evolved due to several factors, including lowering propellant consumption and increasing flexibility in mission planning. Many of the spacecraft that the shuttle rendezvoused with had unique requirements that drove the creation of mission-unique proximity operations. The dockings to the Russian Mir space station and International Space Station (ISS) required further evolution of rendezvous and proximity operations techniques and additional sensors to enhance crew situational awareness. After the Columbia accident, a Rendezvous Pitch Maneuver (RPM) was added to allow tile photography from ISS. Lessons learned from these rendezvous design changes are applicable to future vehicle designs and operations concepts.

  2. Phase-space evolution of x-ray coherence in phase-sensitive imaging.

    Science.gov (United States)

    Wu, Xizeng; Liu, Hong

    2008-08-01

    X-ray coherence evolution in the imaging process plays a key role for x-ray phase-sensitive imaging. In this work we present a phase-space formulation for the phase-sensitive imaging. The theory is reformulated in terms of the cross-spectral density and associated Wigner distribution. The phase-space formulation enables an explicit and quantitative account of partial coherence effects on phase-sensitive imaging. The presented formulas for x-ray spectral density at the detector can be used for performing accurate phase retrieval and optimizing the phase-contrast visibility. The concept of phase-space shearing length derived from this phase-space formulation clarifies the spatial coherence requirement for phase-sensitive imaging with incoherent sources. The theory has been applied to x-ray Talbot interferometric imaging as well. The peak coherence condition derived reveals new insights into three-grating-based Talbot-interferometric imaging and gratings-based x-ray dark-field imaging.

  3. Emergent properties of gene evolution: Species as attractors in phenotypic space

    Science.gov (United States)

    Reuveni, Eli; Giuliani, Alessandro

    2012-02-01

    The question how the observed discrete character of the phenotype emerges from a continuous genetic distance metrics is the core argument of two contrasted evolutionary theories: punctuated equilibrium (stable evolution scattered with saltations in the phenotype) and phyletic gradualism (smooth and linear evolution of the phenotype). Identifying phenotypic saltation on the molecular levels is critical to support the first model of evolution. We have used DNA sequences of ∼1300 genes from 6 isolated populations of the budding yeast Saccharomyces cerevisiae. We demonstrate that while the equivalent measure of the genetic distance show a continuum between lineage distance with no evidence of discrete states, the phenotypic space illustrates only two (discrete) possible states that can be associated with a saltation of the species phenotype. The fact that such saltation spans large fraction of the genome and follows by continuous genetic distance is a proof of the concept that the genotype-phenotype relation is not univocal and may have severe implication when looking for disease related genes and mutations. We used this finding with analogy to attractor-like dynamics and show that punctuated equilibrium could be explained in the framework of non-linear dynamics systems.

  4. Semi-classical approaches to the phase space evolutions in intermediate energy heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Remaud, B; Sebille, F; Raffray, Y; Gregoire, C; Vinet, L

    1986-01-06

    The properties of semi-classical phase space evolution equations - as the Vlasov/Boltzmann equations - are discussed in the context of the heavy ion reaction theory at intermediate energies (from 10 to 100 MeV per nucleon). The generalized coherent state set is shown to form a (over) complete basis for the phase space; then every solution of the Vlasov/Boltzmann equations can be defined as a convolution product of the generalized coherent state basis by an appropriate weight function w. The uniform approximation for w is shown to provide an accurate semi-classical description of fermion systems in their ground state: the examples of fermions in a harmonic well and of cold nuclei are discussed. The solution of the Vlasov equation amounts to follow the time evolution of the coherent states which play the role of a moving basis. For the Boltzmann equation, the collision term is taken into account by explicit or implicit variations of the function w. Typical applications are discussed: nuclear response to the giant monopole resonance excitation, fast nucleon emission in heavy-ion reactions. (orig.).

  5. Space Transportation System Availability Requirements and Its Influencing Attributes Relationships

    Science.gov (United States)

    Rhodes, Russel E.; Adams, TImothy C.

    2008-01-01

    It is essential that management and engineering understand the need for an availability requirement for the customer's space transportation system as it enables the meeting of his needs, goal, and objectives. There are three types of availability, e.g., operational availability, achieved availability, or inherent availability. The basic definition of availability is equal to the mean uptime divided by the sum of the mean uptime plus the mean downtime. The major difference is the inclusiveness of the functions within the mean downtime and the mean uptime. This paper will address tIe inherent availability which only addresses the mean downtime as that mean time to repair or the time to determine the failed article, remove it, install a replacement article and verify the functionality of the repaired system. The definitions of operational availability include the replacement hardware supply or maintenance delays and other non-design factors in the mean downtime. Also with inherent availability the mean uptime will only consider the mean time between failures (other availability definitions consider this as mean time between maintenance - preventive and corrective maintenance) that requires the repair of the system to be functional. It is also essential that management and engineering understand all influencing attributes relationships to each other and to the resultant inherent availability requirement. This visibility will provide the decision makers with the understanding necessary to place constraints on the design definition for the major drivers that will determine the inherent availability, safety, reliability, maintainability, and the life cycle cost of the fielded system provided the customer. This inherent availability requirement may be driven by the need to use a multiple launch approach to placing humans on the moon or the desire to control the number of spare parts required to support long stays in either orbit or on the surface of the moon or mars. It is

  6. Influence of Bulk Carbonaceous Matter on Pluto's Structure and Evolution

    Science.gov (United States)

    McKinnon, W. B.; Stern, S. A.; Weaver, H. A., Jr.; Spencer, J. R.; Moore, J. M.; Young, L. A.; Olkin, C.

    2017-12-01

    The rock/ice mass ratio of the Pluto system is about 2/1 (McKinnon et al., Icarus 287, 2017) [1], though this neglects the potential role of bulk carbonaceous matter ("CHON"), an important cometary component and one likely important in the ancestral Kuiper belt. The wealth of measurements at comet 67P/Churyumov-Gerasimenko (a Jupiter-family comet and thus one formed in the same region of the outer Solar System as Pluto) by Rosetta are particularly instructive. E.g., Davidsson et al. (A&A 592, 2016) [2] propose in their "composition A" that 67P/Ch-G is 25% metal/sulfides, 42% rock/organics, and 32% ice by mass. For their assumed component densities, the overall grain density is 1820 kg/m3. Fulle et al. (MNRAS 462, 2016) [3] posit 5 ± 2 volume % Fe-sulfides of density 4600 kg/m3, 28 ± 5% Mg,Fe-olivines and -pyroxenes of density 3200 kg/m3, 52 ± 12% hydrocarbons of density 1200 kg/m3, and 15 ± 6% ices of 917 kg/m3. This composition yields a primordial grain density (dust + ice) of 1885 ± 240 kg/m3. Both of these cometary density estimates [2,3] are consistent with Pluto-Charon, especially as Pluto's uncompressed (STP) density is close to 1820 kg/m3 and that of the system as a whole is close to 1800 kg/m3 [1]. We consider the potential compositional and structural implications of these proposed 67P/Ch-G compositions when applied to Pluto and Charon. The amount of ice in model A of [2] is a good match to Pluto structural models. Their rock/organics component, however, is taken to be half graphite (2000 kg/m3) by volume. The composition in [3] is more divergent: very ice poor, and on the order of 50% light hydrocarbons by volume. Regardless of the differences between [2] and [3], the possibility of massive internal graphite or carbonaceous layers within Pluto is real. We discuss the possible consequences for Pluto's structure, rock/ice ratio, thermal and chemical evolution, and even interpretation of its gravity field from tectonics. For example, radiogenic heat

  7. An Influence Study of Hydrogen Evolution Characteristics on the Negative Strap Corrosion of Lead Acid Battery

    Directory of Open Access Journals (Sweden)

    Zhong Guobin

    2015-01-01

    Full Text Available Negative strap corrosion is an important reason for the failure of valve regulated lead acid battery. This paper selected the Pb-Sb alloy material and Pb-Sn alloy material, made an investigation on the negative corrosion resistance and hydrogen evolution of these two alloy materials by scanning electron microscope analysis, metallographic analysis, chemical study and linear sweep voltammetry, and discussed the influence of lead alloy hydrogen evolution on the negative strap corrosion. The results showed that the hydrogen evolution reaction rates of the alloys had an impact on the corrosion areas with the maximum thickness of the alloys and the depth of corrosion layers. Greater hydrogen evolution reaction rate can lead to shorter distance between the corrosion area with the maximum thickness and the liquid level; whereas the greater corrosion layer thickness can bring aggravated risk of negative strap corrosion failure.

  8. Modeling Space-Time Dependent Helium Bubble Evolution in Tungsten Armor under IFE Conditions

    International Nuclear Information System (INIS)

    Qiyang Hu; Shahram Sharafat; Nasr Ghoniem

    2006-01-01

    The High Average Power Laser (HAPL) program is a coordinated effort to develop Laser Inertial Fusion Energy. The implosion of the D-T target produces a spectrum of neutrons, X-rays, and charged particles, which arrive at the first wall (FW) at different times within about 2.5 μs at a frequency of 5 to 10 Hz. Helium is one of several high-energy charged particle constituents impinging on the candidate tungsten armored low activation ferritic steel First Wall. The spread of the implanted debris and burn helium energies results in a unique space-time dependent implantation profile that spans about 10 μm in tungsten. Co-implantation of X-rays and other ions results in spatially dependent damage profiles and rapid space-time dependent temperature spikes and gradients. The rate of helium transport and helium bubble formation will vary significantly throughout the implanted region. Furthermore, helium will also be transported via the migration of helium bubbles and non-equilibrium helium-vacancy clusters. The HEROS code was developed at UCLA to model the spatial and time-dependent helium bubble nucleation, growth, coalescence, and migration under transient damage rates and transient temperature gradients. The HEROS code is based on kinetic rate theory, which includes clustering of helium and vacancies, helium mobility, helium-vacancy cluster stability, cavity nucleation and growth and other microstructural features such as interstitial loop evolution, grain boundaries, and precipitates. The HEROS code is based on space-time discretization of reaction-diffusion type equations to account for migration of mobile species between neighboring bins as single atoms, clusters, or bubbles. HAPL chamber FW implantation conditions are used to model helium bubble evolution in the implanted tungsten. Helium recycling rate predictions are compared with experimental results of helium ion implantation experiments. (author)

  9. Planning Cultures and Histories: Influences on the Evolution of Planning Systems and Spatial Development Patterns

    NARCIS (Netherlands)

    Stead, D.; de Vries, J.; Tasan-Kok, T.

    2015-01-01

    This special issue addresses the influences of planning cultures and histories on the evolution of planning systems and spatial development. As well as providing an international comparative perspective on these issues, the collection of articles also engages in a search for new conceptual

  10. Evolution of extortion in the social-influenced prisoner’s dilemma

    Science.gov (United States)

    Wang, Zhipeng; Li, Miao; Wang, Dan; Chen, Qinghe

    2016-01-01

    The introduction of extortion strategy has attracted much attention since it dominates any evolutionary opponent in iterated prisoner’s dilemma games. Despite several studies argue that extortion is difficult to survive under strategy imitation and birth-death updating rules in well-mixed populations, it has recently been proven that a myopic best response rule facilitate the evolution of cooperation and extortion. However, such updating rules require a strong assumption of complete knowledge of all players, which is unlikely to hold in social networks in reality. To solve this problem, we introduce the concept of social influence into the model to limit players’ knowledge within their neighborhood. It turns out that this myopia initiated by social influence prevents players from observing superior strategies and therefore enables cooperators and extortioners to be evolutionarily stable. We also suggest that heterogeneous networks contribute to the evolution of cooperation and extortion under such social influence.

  11. Rapid evolution in insect pests: the importance of space and time in population genomics studies.

    Science.gov (United States)

    Pélissié, Benjamin; Crossley, Michael S; Cohen, Zachary Paul; Schoville, Sean D

    2018-04-01

    Pest species in agroecosystems often exhibit patterns of rapid evolution to environmental and human-imposed selection pressures. Although the role of adaptive processes is well accepted, few insect pests have been studied in detail and most research has focused on selection at insecticide resistance candidate genes. Emerging genomic datasets provide opportunities to detect and quantify selection in insect pest populations, and address long-standing questions about mechanisms underlying rapid evolutionary change. We examine the strengths of recent studies that stratify population samples both in space (along environmental gradients and comparing ancestral vs. derived populations) and in time (using chronological sampling, museum specimens and comparative phylogenomics), resulting in critical insights on evolutionary processes, and providing new directions for studying pests in agroecosystems. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. The Evolution of Nondestructive Evaluation Methods for the Space Shuttle External Tank Thermal Protection System

    Science.gov (United States)

    Walker, James L.; Richter, Joel D.

    2006-01-01

    Three nondestructive evaluation methods are being developed to identify defects in the foam thermal protection system (TPS) of the Space Shuttle External Tank (ET). Shearography is being developed to identify shallow delaminations, shallow voids and crush damage in the foam while terahertz imaging and backscatter radiography are being developed to identify voids and cracks in thick foam regions. The basic theory of operation along with factors affecting the results of these methods will be described. Also, the evolution of these methods from lab tools to implementation on the ET will be discussed. Results from both test panels and flight tank inspections will be provided to show the range in defect sizes and types that can be readily detected.

  13. Real time evolution at finite temperatures with operator space matrix product states

    International Nuclear Information System (INIS)

    Pižorn, Iztok; Troyer, Matthias; Eisler, Viktor; Andergassen, Sabine

    2014-01-01

    We propose a method to simulate the real time evolution of one-dimensional quantum many-body systems at finite temperature by expressing both the density matrices and the observables as matrix product states. This allows the calculation of expectation values and correlation functions as scalar products in operator space. The simulations of density matrices in inverse temperature and the local operators in the Heisenberg picture are independent and result in a grid of expectation values for all intermediate temperatures and times. Simulations can be performed using real arithmetics with only polynomial growth of computational resources in inverse temperature and time for integrable systems. The method is illustrated for the XXZ model and the single impurity Anderson model. (paper)

  14. Real time evolution at finite temperatures with operator space matrix product states

    Science.gov (United States)

    Pižorn, Iztok; Eisler, Viktor; Andergassen, Sabine; Troyer, Matthias

    2014-07-01

    We propose a method to simulate the real time evolution of one-dimensional quantum many-body systems at finite temperature by expressing both the density matrices and the observables as matrix product states. This allows the calculation of expectation values and correlation functions as scalar products in operator space. The simulations of density matrices in inverse temperature and the local operators in the Heisenberg picture are independent and result in a grid of expectation values for all intermediate temperatures and times. Simulations can be performed using real arithmetics with only polynomial growth of computational resources in inverse temperature and time for integrable systems. The method is illustrated for the XXZ model and the single impurity Anderson model.

  15. Space-time evolution of Gaussian wave packets through superlattices containing left-handed layers

    Energy Technology Data Exchange (ETDEWEB)

    Pereyra, P; Romero-Serrano, M [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-Azcapotzalco, Mexico DF (Mexico); Robledo-Martinez, A, E-mail: ppereyra@correo.azc.uam.m, E-mail: a.robledo@mailaps.or [Departamento de EnergIa, Universidad Autonoma Metropolitana-Azcapotzalco, Mexico DF (Mexico)

    2009-05-01

    We study the space-time evolution of Gaussian electromagnetic wave packets moving through (L/R){sup n} superlattices, containing alternating layers of left and right-handed materials. We show that the time spent by the wave packet moving through arbitrary (L/R){sup n} superlattices are well described by the phase time. We show that in the particular case where the thicknesses d{sub L,R} and indices n{sub l,r} of the layers satisfy the condition d{sub L}|n{sub L}| = d{sub R}n{sub R}, the usual band structure becomes a sequence of isolated and equidistant peaks with negative phase times.

  16. The role of urban space design characteristics in influencing social ...

    African Journals Online (AJOL)

    This paper is based on a study carried out in Old Town Mombasa, a Swahili city in Kenya, situated along the East African Coast. Its focus is on social life of the town's street system as a correlate of urban space design characteristics. Urban design elements within the streets have been disregarded resulting in spaces that do ...

  17. Genomic potential hypothesis of evolution: a concept of biogenesis in habitable spaces of the universe.

    Science.gov (United States)

    Schwabe, Christian

    2002-11-01

    The new hypothesis of evolution establishes a contiguity of life sciences with cosmology, physics, and chemistry, and provides a basis for the search for life on other planets. Chemistry is the sole driving force of the assembly of life, under the subtle guidance exerted by bonding orbital geometry. That phenomenon leads to multiple origins that function on the same principles but are different to the extent that their nucleic acid core varies. Thus, thoughts about the origins of life and the development of complexity have been transferred from the chance orientation of the past to the realm of atomic structures, which are subject to the laws of thermodynamics and kinetics. Evolution is a legitimate subject of basic science, and the complexity of life will submit to the laws of chemistry and physics as the problem is viewed from a new perspective. The paradigm connects life to the big events that formed every sphere of our living space and that keeps conditions fine-tuned for life to persist, perhaps a billion years or more. The "genomic potential" hypothesis leads to the prediction that life like ours is likely to exist in galaxies that are as distant from the origin of the universe as the Milky Way, and that the habitable zone of our galaxy harbors other living planets as well. Copyright 2002 Wiley-Liss, Inc.

  18. Evolution of interstellar dust in light of Herschel Space Observatory data

    International Nuclear Information System (INIS)

    Arab, Heddy

    2012-01-01

    Interstellar dust grains are nanometer to micrometer sized particles. Although a weak proportion of the total interstellar mass is at solid state, dust plays a fundamental role in the evolution of the interstellar medium (ISM) and of the galaxy itself. Grains can be observed in the UV and visible wavelength through extinction whereas their emission is in the infrared to submillimeter range. Astrophysical observations combined to numerical models and laboratory studies of dust analogs improve our comprehension of the nature and the physics of interstellar grains. For example, evidence of dust evolution in the interstellar medium are now numerous, even if the physical processes responsible of this evolution are still poorly understood. Understanding how grains evolve with physical conditions requires observations of various environments. Photodissociation regions (PDRs) are zones of the ISM where the radiation field and the local density vary on short spatial scales (∼10''- 20''). Moreover the many gas tracers offer the opportunity to constraint efficiently the physical conditions within PDRs. Past missions such as ISO and Spitzer allow to study the evolution of dust in the near-Infrared range. At longer wavelengths, where the emission is dominated by the grains at thermal equilibrium with the radiation, instruments rarely resolved the spatial emission in PDRs. PACS and SPIRE instruments onboard Herschel Space Observatory provide spectro-photometric data between 70 and 500 μm. Their high spatial resolution (from 5 to 35 arcmin) makes these observations ideal for the study of dust evolution in PDRs. We present here an analysis of Herschel observations of three PDRs: the Orion Bar, the Horsehead and NGC 7023 East, characterized by different physical conditions. By combining these data with shorter wavelength observations from Spitzer, we can study the dust emission spectrum from 3.6 to 500 μm at different positions within the PDR. Intensity profiles are extracted

  19. Asteroid age distributions determined by space weathering and collisional evolution models

    Science.gov (United States)

    Willman, Mark; Jedicke, Robert

    2011-01-01

    We provide evidence of consistency between the dynamical evolution of main belt asteroids and their color evolution due to space weathering. The dynamical age of an asteroid's surface (Bottke, W.F., Durda, D.D., Nesvorný, D., Jedicke, R., Morbidelli, A., Vokrouhlický, D., Levison, H. [2005]. Icarus 175 (1), 111-140; Nesvorný, D., Jedicke, R., Whiteley, R.J., Ivezić, Ž. [2005]. Icarus 173, 132-152) is the time since its last catastrophic disruption event which is a function of the object's diameter. The age of an S-complex asteroid's surface may also be determined from its color using a space weathering model (e.g. Willman, M., Jedicke, R., Moskovitz, N., Nesvorný, D., Vokrouhlický, D., Mothé-Diniz, T. [2010]. Icarus 208, 758-772; Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M. [2004]. Nature 429, 275-277; Willman, M., Jedicke, R., Nesvorny, D., Moskovitz, N., Ivezić, Ž., Fevig, R. [2008]. Icarus 195, 663-673. We used a sample of 95 S-complex asteroids from SMASS and obtained their absolute magnitudes and u, g, r, i, z filter magnitudes from SDSS. The absolute magnitudes yield a size-derived age distribution. The u, g, r, i, z filter magnitudes lead to the principal component color which yields a color-derived age distribution by inverting our color-age relationship, an enhanced version of the 'dual τ' space weathering model of Willman et al. (2010). We fit the size-age distribution to the enhanced dual τ model and found characteristic weathering and gardening times of τw = 2050 ± 80 Myr and τg=4400-500+700Myr respectively. The fit also suggests an initial principal component color of -0.05 ± 0.01 for fresh asteroid surface with a maximum possible change of the probable color due to weathering of Δ PC = 1.34 ± 0.04. Our predicted color of fresh asteroid surface matches the color of fresh ordinary chondritic surface of PC1 = 0.17 ± 0.39.

  20. The Evolution of Technology in the Deep Space Network: A History of the Advanced Systems Program

    Science.gov (United States)

    Layland, J. W.; Rauch, L. L.

    1994-01-01

    The Deep Space Network (DSN) of 1995 might be described as the evolutionary result of 45 years of deep space communication and navigation, together with the synergistic activities of radio science and radar and radio astronomy. But the evolution of the DSN did not just happen - it was carefully planned and created. The evolution of the DSN has been an ongoing engineering activity, and engineering is a process of problem solving under constraints, one of which is technology. In turn, technology is the knowledge base providing the capability and experience for practical application of various areas of science, when needed. The best engineering solutions result from optimization under the fewest constraints, and if technology needs are well anticipated (ready when needed), then the most effective engineering solution is possible. Throughout the history of the DSN it has been the goal and function of DSN advanced technology development (designated the DSN Advanced Systems Program from 1963 through 1994) to supply the technology needs of the DSN when needed, and thus to minimize this constraint on DSN engineering. Technology often takes considerable time to develop, and when that happens, it is important to have anticipated engineering needs; at times, this anticipation has been by as much as 15 years. Also, on a number of occasions, mission malfunctions or emergencies have resulted in unplanned needs for technology that has, in fact, been available from the reservoir of advanced technology provided by the DSN Advanced Systems Program. Sometimes, even DSN engineering personnel fail to realize that the organization of JPL permits an overlap of DSN advanced technology activities with subsequent engineering activities. This can result in the flow of advanced technology into DSN engineering in a natural and sometimes almost unnoticed way. In the following pages, we will explore some of the many contributions of the DSN Advanced Systems Program that were provided to DSN

  1. Influence of the surroundings conditions on the evolution of elastomers in the nuclear field

    International Nuclear Information System (INIS)

    Davenas, J.; Stevenson, I.; Celette, N.; David, L.; Vigier, G.; David, L.

    2006-01-01

    The evolution under radiations of EPDM elastomers used as cable insulators reveals the determining role of the surrounding atmosphere. The formation of unsaturated bonds and a recovery of the reticulation are revealed for irradiations in inert atmosphere, whereas a lot of oxidized species are formed in presence of oxygen. The dynamic mechanical relaxation spectroscopy shows a decrease of the molecular mobility in all the cases. This ones results of the reticulation under inert atmosphere, but its origin is less clear during the radio-oxidation where the chain cleavages constitute the main process. The evolution of the conservation modulus with the irradiation dose is in agreement with the waited evolution after the melting of the crystallites. The number of reticulation intersection increases until a dose corresponding to the complete consumption of diene, for decreasing then under the influence of the chain cleavages. The crystallites growth due to chain cleavages explains then the evolution at ambient temperature in presence of oxygen. The mechanical properties at the great deformations show the role of reinforcement of the crystallites at ambient temperature which disappears during the crystallites melting. The evolution of the EPDM properties results of a complex equilibrium between reticulations, chain cleavages and crystallites growth, which is controlled by the temperature and the atmosphere. (O.M.)

  2. Influence of pinches on magnetic reconnection in turbulent space plasmas

    Science.gov (United States)

    Olshevsky, Vyacheslav; Lapenta, Giovanni; Markidis, Stefano; Divin, Andrey

    A generally accepted scenario of magnetic reconnection in space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is widely studied in pinches, current channels embedded into twisted magnetic fields. No model of magnetic reconnection in space plasmas considers both null-points and pinches as peers. We have performed a particle-in-cell simulation of magnetic reconnection in a three-dimensional configuration where null-points are present nitially, and Z-pinches are formed during the simulation. The X-points are relatively stable, and no substantial energy dissipation is associated with them. On contrary, turbulent magnetic reconnection in the pinches causes the magnetic energy to decay at a rate of approximately 1.5 percent per ion gyro period. Current channels and twisted magnetic fields are ubiquitous in turbulent space plasmas, so pinches can be responsible for the observed high magnetic reconnection rates.

  3. Vestibular factors influencing the biomedical support of humans in space.

    Science.gov (United States)

    Lichtenberg, B K

    1988-01-01

    This paper will describe the biomedical support aspects of humans in space with respect to the vestibular system. The vestibular system is thought to be the primary sensory system involved in the short-term effects of space motion sickness although there is increasing evidence that many factors play a role in this complex set of symptoms. There is the possibility that an individual's inner sense of orientation may be strongly coupled with the susceptibility to space motion sickness. A variety of suggested countermeasures for space motion sickness will be described. Although there are no known ground-based tests that can predict space motion sickness, the search should go on. The long term effects of the vestibular system in weightlessness are still relatively unknown. Some preliminary data has shown that the otoconia are irregular in size and distribution following extended periods of weightlessness. The ramifications of this data are not yet known and because the data was obtained on lower order animals, definitive studies and results must wait until the space station era when higher primates can be studied for long durations. This leads us to artificial gravity, the last topic of this paper. The vestibular system is intimately tied to this question since it has been shown on Earth that exposure to a slow rotating room causes motion sickness for some period of time before adaptation occurs. If the artificial gravity is intermittent, will this mean that people will get sick every time they experience it? The data from many astronauts returning to Earth indicates that a variety of sensory illusions are present, especially immediately upon return to a 1-g environment. Oscillopsia or apparent motion of the visual surround upon head motion along with inappropriate eye motions for a given head motion, all indicate that there is much to be studied yet about the vestibular and CNS systems reaction to a sudden application of a steady state acceleration field like 1-g. From

  4. Simulation of the space-time evolution of color-flux tubes (guidelines to the TERMITE program)

    International Nuclear Information System (INIS)

    Dyrek, A.

    1990-08-01

    We give the description of the computer program which simulates boost-invariant evolution of color-flux tubes in high-energy processes. The program provides a graphic demonstration of space-time trajectories of created particles and can also be used as Monte-Carlo generator of events. (author)

  5. A Markov Chain Monte Carlo version of the genetic algorithm Differential Evolution: easy Bayesian computing for real parameter spaces

    NARCIS (Netherlands)

    Braak, ter C.J.F.

    2006-01-01

    Differential Evolution (DE) is a simple genetic algorithm for numerical optimization in real parameter spaces. In a statistical context one would not just want the optimum but also its uncertainty. The uncertainty distribution can be obtained by a Bayesian analysis (after specifying prior and

  6. WRF simulation of a severe hailstorm over Baramati: a study into the space-time evolution

    Science.gov (United States)

    Murthy, B. S.; Latha, R.; Madhuparna, H.

    2018-04-01

    Space-time evolution of a severe hailstorm occurred over the western India as revealed by WRF-ARW simulations are presented. We simulated a specific event centered over Baramati (18.15°N, 74.58°E, 537 m AMSL) on March 9, 2014. A physical mechanism, proposed as a conceptual model, signifies the role of multiple convective cells organizing through outflows leading to a cold frontal type flow, in the presence of a low over the northern Arabian Sea, propagates from NW to SE triggering deep convection and precipitation. A `U' shaped cold pool encircled by a converging boundary forms to the north of Baramati due to precipitation behind the moisture convergence line with strong updrafts ( 15 ms-1) leading to convective clouds extending up to 8 km in a narrow region of 30 km. The outflows from the convective clouds merge with the opposing southerly or southwesterly winds from the Arabian Sea and southerly or southeasterly winds from the Bay of Bengal resulting in moisture convergence (maximum 80 × 10-3 g kg-1 s-1). The vertical profile of the area-averaged moisture convergence over the cold pool shows strong convergence above 850 hPa and divergence near the surface indicating elevated convection. Radar reflectivity (50-60 dBZ) and vertical component of vorticity maximum ( 0.01-0.14 s-1) are observed along the convergence zone. Stratiform clouds ahead of the squall line and parallel wind flow at 850 hPa and nearly perpendicular flow at higher levels relative to squall line as evidenced by relatively low and wide-spread reflectivity suggests that organizational mode of squall line may be categorized as `Mixed Mode' type where northern part can be a parallel stratiform while the southern part resembles with a leading stratiform. Simulated rainfall (grid scale 27 km) leads the observed rainfall by 1 h while its magnitude is 2 times of the observed rainfall (grid scale 100 km) derived from Kalpana-1. Thus, this study indicates that under synoptically favorable conditions

  7. Influence of space charge during the injection in Saturne II

    International Nuclear Information System (INIS)

    Lemaire, J.L.

    Calculations were made in which a fixed acceptance window, established since the beginning of the injection, was considered, and a filling pattern that was a linear function of time was supposed. Evidently, these conditions are no longer met if the space charge modifies the wave number of the beam and, consequently, the filling rate changes with time. The importance of these conditions upon injection for the theoretical operation point zone 3 is reported

  8. Open Space Office and it's Influence on Satisfaction of Workers

    OpenAIRE

    Novotná, Marta

    2015-01-01

    This bachelor thesis focuses on open space office in relation to satisfaction with employment. It focuses on research of factors of this specific working environment and tries to check hypothesis talking about negative impact on overal satsfacton with job. Through the research conducted within one company this bachelor thesis present evaluation of factos of working environment and show overal impact of these factors on satisfaction with job. This bachelor thesis finds out that noise and disco...

  9. Space-time evolution of whistler mode wave growth in the magnetosphere

    International Nuclear Information System (INIS)

    Carlson, C.R.; Helliwell, R.A.; Inan, U.S.

    1990-01-01

    A new model is developed to simulate the space-time evolution of a propagating coherent whistler mode wave pulse in the magnetosphere. The model is applied to the case of single frequency (2-6 kHz) wave pulses injected into the magnetosphere near L ≅ 4, using the VLF transmitting facility at Siple Station, Antarctica. The mechanism for growth is cyclotron resonance between the circularly polarized waves and the gyrating energetic electrons of the radiation belts. Application of this model reproduces observed exponential wave growth up to a saturated level. Additionally, the model predicts the observed initial linear increase in the output frequency versus time. This is the first time these features have been reproduced using applied wave intensities small enough to be consistent with satellite measurements. The center velocities of the electrons entering the wave pulse are selected in a way which maximizes the growth rate. The results show the importance of the transient aspects in the wave growth process. The growth established as the wave propagates toward the geomagnetic equator results in a spatially advancing wave phase structure due mainly to the geomagnetic inhomogeneity. Through the feedback of this radiation upon other electrons, conditions are established which result in a linearly increasing output frequency with time

  10. Robust numerical simulation of porosity evolution in chemical vapor infiltration III: three space dimension

    CERN Document Server

    Jin Shi

    2003-01-01

    Chemical vapor infiltration (CVI) process is an important technology to fabricate ceramic matrix composites (CMC's). In this paper, a three-dimension numerical model is presented to describe pore microstructure evolution during the CVI process. We extend the two-dimension model proposed in [S. Jin, X.L. Wang, T.L. Starr, J. Mater. Res. 14 (1999) 3829; S. Jin. X.L. Wang, T.L. Starr, X.F. Chen, J. Comp. Phys. 162 (2000) 467], where the fiber surface is modeled as an evolving interface, to the three space dimension. The 3D method keeps all the virtue of the 2D model: robust numerical capturing of topological changes of the interface such as the merging, and fast detection of the inaccessible pores. For models in the kinetic limit, where the moving speed of the interface is constant, some numerical examples are presented to show that this three-dimension model will effectively track the change of porosity, close-off time, location and shape of all pores.

  11. Evolution of competition in energy alternative pathway and the influence of energy policy on economic growth

    International Nuclear Information System (INIS)

    Yang, Honglin; Wang, Lin; Tian, Lixin

    2015-01-01

    This work is devoted to the evolution of the competition of energy alternative pathway in China, and the influence of energy policy on economic growth by using a dynamical system method. Firstly, the relation between energy and economic growth is taken into account, and a dynamic evolution model is established. It is observed that Hopf bifurcation and chaotic behavior occurs with the varying investment in renewable energy production. Secondly, when there is no policy intervention in energy market, the evolution of competition in energy alternative pathway is also investigated. Thirdly, the system parameters are also identified by using an artificial neural network method on the basis of certain empirical statistical data in China, and the dynamics of the parameters-identified system are studied. Finally, the influences of energy policy on economic growth are empirically analyzed, and some policy recommendations are given based on the results of empirical analysis. - Highlights: • Modeling the energy economy system via the method of dynamic system. • Attaining the chaotic attractor of the energy production and economic system. • Discovering the Hopf bifurcation when the investment changes. • Proposing the alternative pathway of free competition in energy production. • Determining the turning points of parameters related to policy regulation

  12. Evolution of the Digital Society Reveals Balance between Viral and Mass Media Influence

    Science.gov (United States)

    Kleineberg, Kaj-Kolja; Boguñá, Marián

    2014-07-01

    Online social networks (OSNs) enable researchers to study the social universe at a previously unattainable scale. The worldwide impact and the necessity to sustain the rapid growth of OSNs emphasize the importance of unraveling the laws governing their evolution. Empirical results show that, unlike many real-world growing networked systems, OSNs follow an intricate path that includes a dynamical percolation transition. In light of these results, we present a quantitative two-parameter model that reproduces the entire topological evolution of a quasi-isolated OSN with unprecedented precision from the birth of the network. This allows us to precisely gauge the fundamental macroscopic and microscopic mechanisms involved. Our findings suggest that the coupling between the real preexisting underlying social structure, a viral spreading mechanism, and mass media influence govern the evolution of OSNs. The empirical validation of our model, on a macroscopic scale, reveals that virality is 4-5 times stronger than mass media influence and, on a microscopic scale, individuals have a higher subscription probability if invited by weaker social contacts, in agreement with the "strength of weak ties" paradigm.

  13. Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash.

    Science.gov (United States)

    Wu, Mengxue; Li, Chen; Yao, Wu

    2017-01-11

    In cement-based pastes, the relationship between the complex phase assemblage and mechanical properties is usually described by the "gel/space ratio" descriptor. The gel/space ratio is defined as the volume ratio of the gel to the available space in the composite system, and it has been widely studied in the cement unary system. This work determines the gel/space ratio in the cement-silica fume-fly ash ternary system (C-SF-FA system) by measuring the reaction degrees of the cement, SF, and FA. The effects that the supplementary cementitious material (SCM) replacements exert on the evolution of the gel/space ratio are discussed both theoretically and practically. The relationship between the gel/space ratio and compressive strength is then explored, and the relationship disparities for different mix proportions are analyzed in detail. The results demonstrate that the SCM replacements promote the gel/space ratio evolution only when the SCM reaction degree is higher than a certain value, which is calculated and defined as the critical reaction degree (CRD). The effects of the SCM replacements can be predicted based on the CRD, and the theological predictions agree with the test results quite well. At low gel/space ratios, disparities in the relationship between the gel/space ratio and the compressive strength are caused by porosity, which has also been studied in cement unary systems. The ratio of cement-produced gel to SCM-produced gel ( G C to G S C M ratio) is introduced for use in analyzing high gel/space ratios, in which it plays a major role in creating relationship disparities.

  14. Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash

    Directory of Open Access Journals (Sweden)

    Mengxue Wu

    2017-01-01

    Full Text Available In cement-based pastes, the relationship between the complex phase assemblage and mechanical properties is usually described by the “gel/space ratio” descriptor. The gel/space ratio is defined as the volume ratio of the gel to the available space in the composite system, and it has been widely studied in the cement unary system. This work determines the gel/space ratio in the cement-silica fume-fly ash ternary system (C-SF-FA system by measuring the reaction degrees of the cement, SF, and FA. The effects that the supplementary cementitious material (SCM replacements exert on the evolution of the gel/space ratio are discussed both theoretically and practically. The relationship between the gel/space ratio and compressive strength is then explored, and the relationship disparities for different mix proportions are analyzed in detail. The results demonstrate that the SCM replacements promote the gel/space ratio evolution only when the SCM reaction degree is higher than a certain value, which is calculated and defined as the critical reaction degree (CRD. The effects of the SCM replacements can be predicted based on the CRD, and the theological predictions agree with the test results quite well. At low gel/space ratios, disparities in the relationship between the gel/space ratio and the compressive strength are caused by porosity, which has also been studied in cement unary systems. The ratio of cement-produced gel to SCM-produced gel ( G C to G S C M ratio is introduced for use in analyzing high gel/space ratios, in which it plays a major role in creating relationship disparities.

  15. Chemistry in interstellar space. [environment characteristics influencing reaction dynamics

    Science.gov (United States)

    Donn, B.

    1973-01-01

    The particular characteristics of chemistry in interstellar space are determined by the unique environmental conditions involved. Interstellar matter is present at extremely low densities. Large deviations from thermodynamic equilibrium are, therefore, to be expected. A relatively intense ultraviolet radiation is present in many regions. The temperatures are in the range from 5 to 200 K. Data concerning the inhibiting effect of small activation energies in interstellar clouds are presented in a table. A summary of measured activation energies or barrier heights for exothermic exchange reactions is also provided. Problems of molecule formation are discussed, taking into account gas phase reactions and surface catalyzed processes.

  16. The Influence of Hierarchy and Layout Geometry in the Design of Learning Spaces

    Science.gov (United States)

    Smith, Charlie

    2017-01-01

    For a number of years, higher education has moved away from didactic teaching toward collaborative and self-directed learning. This paper discusses how the configuration and spatial geometry of learning spaces influences engagement and interaction, with a particular focus on hierarchies between people within the space. Layouts, presented as…

  17. "Space and Consequences": The Influence of the Roundtable Classroom Design on Student Dialogue

    Science.gov (United States)

    Parsons, Caroline S.

    2016-01-01

    This study sought to explore how the design of both physical and virtual learning spaces influence student dialogue in a modern university. Qualitative analysis of the learning spaces in an undergraduate liberal arts program was conducted. Interview and focus group data from students and faculty, in addition to classroom observations, resulted in…

  18. Time Evolution Of The Wigner Function In Discrete Quantum Phase Space For A Soluble Quasi-spin Model

    CERN Document Server

    Galetti, D

    2000-01-01

    Summary: The discrete phase space approach to quantum mechanics of degrees of freedom without classical counterparts is applied to the many-fermions/quasi-spin Lipkin model. The Wigner function is written for some chosen states associated to discrete angle and angular momentum variables, and the time evolution is numerically calculated using the discrete von Neumann-Liouville equation. Direct evidences in the time evolution of the Wigner function are extracted that identify a tunnelling effect. A connection with an $SU(2)$-based semiclassical continuous approach to the Lipkin model is also presented.

  19. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    International Nuclear Information System (INIS)

    Zhang, Yanwen; Wang, Lumin; Caro, Alfredo; Weber, William J.; Univ. of Tennessee, Knoxville, TN

    2015-01-01

    A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel to binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys

  20. Influence of the Mesh Geometry Evolution on Gearbox Dynamics during Its Maintenance

    Science.gov (United States)

    Dąbrowski, Z.; Dziurdź, J.; Klekot, G.

    2017-12-01

    Toothed gears constitute the necessary elements of power transmission systems. They are applied as stationary devices in drive systems of road vehicles, ships and crafts as well as airplanes and helicopters. One of the problems related to the toothed gears usage is the determination of their technical state or its evolutions. Assuming that the gear slippage velocity is attributed to vibrations and noises generated by cooperating toothed wheels, the application of a simple cooperation model of rolled wheels of skew teeth is proposed for the analysis of the mesh evolution influence on the gear dynamics. In addition, an example of utilising an ordinary coherence function for investigating evolutionary mesh changes related to the effects impossible to be described by means of the simple kinematic model is presented.

  1. Dynamical evolution of space debris on high-elliptical orbits near high-order resonance zones

    Science.gov (United States)

    Kuznetsov, Eduard; Zakharova, Polina

    Orbital evolution of objects on Molniya-type orbits is considered near high-order resonance zones. Initial conditions correspond to high-elliptical orbits with the critical inclination 63.4 degrees. High-order resonances are analyzed. Resonance orders are more than 5 and less than 50. Frequencies of perturbations caused by the effect of sectorial and tesseral harmonics of the Earth's gravitational potential are linear combinations of the mean motion of a satellite, angular velocities of motion of the pericenter and node of its orbit, and the angular velocity of the Earth. Frequencies of perturbations were calculated by taking into account secular perturbations from the Earth oblateness, the Moon, the Sun, and a solar radiation pressure. Resonance splitting effect leads to three sub-resonances. The study of dynamical evolution on long time intervals was performed on the basis of the results of numerical simulation. We used "A Numerical Model of the Motion of Artificial Earth's Satellites", developed by the Research Institute of Applied Mathematics and Mechanics of the Tomsk State University. The model of disturbing forces taken into account the main perturbing factors: the gravitational field of the Earth, the attraction of the Moon and the Sun, the tides in the Earth’s body, the solar radiation pressure, taking into account the shadow of the Earth, the Poynting-Robertson effect, and the atmospheric drag. Area-to-mass ratio varied from small values corresponding to satellites to big ones corresponding to space debris. The locations and sizes of resonance zones were refined from numerical simulation. The Poynting-Robertson effect results in a secular decrease in the semi-major axis of a spherically symmetrical satellite. In resonance regions the effect weakens slightly. Reliable estimates of secular perturbations of the semi-major axis were obtained from the numerical simulation. Under the Poynting-Robertson effect objects pass through the regions of high

  2. Comparative empirical analysis of flow-weighted transit route networks in R-space and evolution modeling

    Science.gov (United States)

    Huang, Ailing; Zang, Guangzhi; He, Zhengbing; Guan, Wei

    2017-05-01

    Urban public transit system is a typical mixed complex network with dynamic flow, and its evolution should be a process coupling topological structure with flow dynamics, which has received little attention. This paper presents the R-space to make a comparative empirical analysis on Beijing’s flow-weighted transit route network (TRN) and we found that both the Beijing’s TRNs in the year of 2011 and 2015 exhibit the scale-free properties. As such, we propose an evolution model driven by flow to simulate the development of TRNs with consideration of the passengers’ dynamical behaviors triggered by topological change. The model simulates that the evolution of TRN is an iterative process. At each time step, a certain number of new routes are generated driven by travel demands, which leads to dynamical evolution of new routes’ flow and triggers perturbation in nearby routes that will further impact the next round of opening new routes. We present the theoretical analysis based on the mean-field theory, as well as the numerical simulation for this model. The results obtained agree well with our empirical analysis results, which indicate that our model can simulate the TRN evolution with scale-free properties for distributions of node’s strength and degree. The purpose of this paper is to illustrate the global evolutional mechanism of transit network that will be used to exploit planning and design strategies for real TRNs.

  3. The influence of thermomechanical processing on microstructural evolution of Ti600 titanium alloy

    International Nuclear Information System (INIS)

    Han Yuanfei; Zeng Weidong; Qi Yunlian; Zhao Yongqing

    2011-01-01

    Highlights: → Temperature and strain rate have great influence on the microstructure features. → The formation of sub-grain and dislocation wall is the typically microstructure features observed in the β single-phase. → The elongated lamellar α platelets kinked increasingly and break up under the α + β processing conditions. → The softening mechanisms of the Ti600 alloy hot compressed at 1000-1100 deg. C are mainly dynamic recovery. - Abstract: The influences of thermomechanical processing on microstructural evolution of Ti600 alloy were studied in the temperature range of 800-1100 deg. C, and at the strain rate of 0.001-10 s -1 . During the isothermal compression experiment, the flow stress-strain curves are examined in the β single-phase and in the α + β two-phase regions. The results show that the thermomechanical processing parameters have significant influences on the microstructure of Ti600 alloy, especially on the grain size, morphologies of α phase. Moreover, the microstructural evolution was analyzed by optical microstructure (OM) and transmission electron microscopy (TEM). It was found that typical of dynamic recovery and dynamic recrystallization phenomenon occurring in the thermomechanical processing. These results will optimize the microstructural control for hot working of Ti600 alloy and deepen the understanding of the flow softening mechanism of near-α titanium alloy.

  4. The Evolution of On-Board Emergency Training for the International Space Station Crew

    Science.gov (United States)

    LaBuff, Skyler

    2015-01-01

    The crew of the International Space Station (ISS) receives extensive ground-training in order to safely and effectively respond to any potential emergency event while on-orbit, but few people realize that their training is not concluded when they launch into space. The evolution of the emergency On- Board Training events (OBTs) has recently moved from paper "scripts" to an intranet-based software simulation that allows for the crew, as well as the flight control teams in Mission Control Centers across the world, to share in an improved and more realistic training event. This emergency OBT simulator ensures that the participants experience the training event as it unfolds, completely unaware of the type, location, or severity of the simulated emergency until the scenario begins. The crew interfaces with the simulation software via iPads that they keep with them as they translate through the ISS modules, receiving prompts and information as they proceed through the response. Personnel in the control centers bring up the simulation via an intranet browser at their console workstations, and can view additional telemetry signatures in simulated ground displays in order to assist the crew and communicate vital information to them as applicable. The Chief Training Officers and emergency instructors set the simulation in motion, choosing the type of emergency (rapid depressurization, fire, or toxic atmosphere) and specific initial conditions to emphasize the desired training objectives. Project development, testing, and implementation was a collaborative effort between ISS emergency instructors, Chief Training Officers, Flight Directors, and the Crew Office using commercial off the shelf (COTS) hardware along with simulation software created in-house. Due to the success of the Emergency OBT simulator, the already-developed software has been leveraged and repurposed to develop a new emulator used during fire response ground-training to deliver data that the crew receives

  5. Spatial Evolution of Producer Service Sectors and Its Influencing Factors in Cities: A Case Study of Hangzhou, China

    Directory of Open Access Journals (Sweden)

    Yizhou Wu

    2018-03-01

    Full Text Available Producer service industries are an important feature in the current development of a metropolis. Researchers from different countries are increasingly concerned about location changes and the motives of producer service sectors in cities. Given the rapid development of producer service sectors in developing countries, this study examines changes in the distribution of producer service sectors over the past decade and factors influencing them in a case study using the city of Hangzhou in China. Results show that Hangzhou’s producer service sector is still mainly concentrated in the central business district (CBD. However, a distinct trend of diffusion to suburban areas was observed, which formed several secondary clusters on the periphery of the city. Locations of the CBD, sub-centers, and professional clusters of producer service sectors established by the government are the most important factors that affect the spatial distribution of producer service sectors. The main influencing factors for the spatial evolution of producer service sectors are: (1 the high development cost and residential suburbanization of the central areas of the city promote the development of producer service sectors toward the periphery; (2 city planning has guided the clustering of producer service sectors on the city’s CBD and secondary city centers; (3 city renewal has provided personalized and diversified development space for producer service sectors; (4 incentive policies introduced by the government, such as rentals, and taxes have enhanced the orderly aggregation of producer service sectors.

  6. The evolution of C/O in dwarf galaxies from Hubble Space Telescope FOS observations

    Science.gov (United States)

    Garnett, D. R.; Skillman, E. D.; Dufour, R. J.; Peimbert, M.; Torres-Peimbert, S.; Terlevich, R.; Terlevich, E.; Shields, G. A.

    1995-01-01

    We present UV observations of seven H II regions in low-luminosity dwarf irregular galaxies and the Magellanic Clouds obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) in order to measure the C/O abundance ratio in the interstellar medium (ISM) of those galaxies. We measure both O III 1666 A and C III 1909 A in our spectra, enabling us to determine C(+2)/O(+2) with relatively small uncertainties. The results from our HST observations show a continuous increase in C/O with increasing O/H, consistent with a power law having an index of 0.43 +/- 0.09 over the range -4.7 to -3.6 in log (O/H). One possible interpretation of this trend is that the most metal-poor galaxies are the youngest and dominated by the products of early enrichment by massive stars, while more metal-rich galaxies show increasing, delayed contributions of carbon from intermediate-mass stars. Our results also suggest that it may not be appropiate to combine abundances in irregular galaxies with those in spiral galaxies to study the evolution of chemical abundances. Our measured C/O ratios in the most metal-poor galaxies are consistent with predictions of nucleosynthesis from massive stars for Weaver & Woosley's best estimate for the 12C(alpha, gamma) 16O nuclear reaction rate, assuming negligible contanmination from carbon produced in intermediate-mass stars in these galaxies. We detect a weak N III 1750 A multiplet in SMC N88A and obtain interesting upper limits for two other objects. Our 2 sigma uppr limits on the 1750 A feature indicate that the N(+2)/O(+2) ratios in these objects are not significantly larger than the N(+)/O(+) ratios measured from optical spectra. This behavior is consistent with predictions of photionization models, although better detections of N III are needed to confirm the results.

  7. On the influence of atomic mixing on the evolution of ion-implantation profiles

    International Nuclear Information System (INIS)

    Gras-Marti, A.; Jimenez-Rodriguez, J.J.; Peon-Fernandez, J.; Rodriguez-Vidal, M.

    1982-01-01

    Various processes contributing to the evolution of high-fluence implantation profiles in solids are considered within a general scheme. In particular the influence of atomic mixing is analysed. A Green function is derived which contains all the information on the instantaneous profile. In the Gaussian approximation, simple expressions for parameters which describe the ion-induced relocation effects on the depth profile are found. The contributions of recoil and cascade mixing are discussed. The relative significance of diffusive and collisional processes on the profiles can also be assessed. (author)

  8. Does the nature of science influence college students' learning of biological evolution?

    Science.gov (United States)

    Butler, Wilbert, Jr.

    This quasi-experimental, mixed-methods study assessed the influence of the nature of science (NOS) instruction on college students' learning of biological evolution. In this research, conducted in two introductory biology courses, in each course the same instruction was employed, with one important exception: in the experimental section students were involved in an explicit, reflective treatment of the nature of science (Explicit, reflective NOS), in the traditional treatment section, NOS was implicitly addressed (traditional treatment). In both sections, NOS aspects of science addressed included is tentative, empirically based, subjective, inferential, and based on relationship between scientific theories and laws. Students understanding of evolution, acceptance of evolution, and understanding of the nature of science were assessed before, during and after instruction. Data collection entailed qualitative and quantitative methods including Concept Inventory for Natural Selection (CINS), Measure of Acceptance of the Theory of Evolution (MATE) survey, Views of nature of Science (VNOS-B survey), as well as interviews, classroom observations, and journal writing to address understand students' views of science and understanding and acceptance of evolution. The quantitative data were analyzed via inferential statistics and the qualitative data were analyzed using grounded theory. The data analysis allowed for the construction and support for four assertions: Assertion 1: Students engaged in explicit and reflective NOS specific instruction significantly improved their understanding of the nature of science concepts. Alternatively, students engaged in instruction using an implicit approach to the nature of science did not improve their understanding of the nature of science to the same degree. The VNOS-B results indicated that students in the explicit, reflective NOS class showed the better understanding of the NOS after the course than students in the implicit NOS class

  9. The evolution of behavior guidance: a history of professional, practice, corporate and societal influences.

    Science.gov (United States)

    Strange, David M

    2014-01-01

    Behavior guidance in pediatric dentistry is a composite of influences including expert opinion, historical precedent, scientific studies, and social factors including the law and the media. The early icons of pediatric dentistry injected their personal views on child management, and those often reflected the child-rearing norms of the times. The business of pediatric dentistry with its efficiency and quality orientations also shaped approaches to behavior management. Scientific studies contributed minimally. A major influence on behavior guidelines in recent years has been external scrutiny of techniques prompted by media and other exposure of both private practice and corporate management of children. Changing parenting and reaction of society to authority have also had significant impact on behavior. This paper describes in more detail the evolution of behavior guidance and the subsequent codification of practices into professionally derived guidelines.

  10. THE INFLUENCE OF THERMAL EVOLUTION IN THE MAGNETIC PROTECTION OF TERRESTRIAL PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Zuluaga, Jorge I.; Bustamante, Sebastian; Cuartas, Pablo A. [Instituto de Fisica-FCEN, Universidad de Antioquia, Calle 67 No. 53-108, Medellin (Colombia); Hoyos, Jaime H., E-mail: jzuluaga@fisica.udea.edu.co, E-mail: sbustama@pegasus.udea.edu.co, E-mail: p.cuartas@fisica.udea.edu.co, E-mail: jhhoyos@udem.edu.co [Departamento de Ciencias Basicas, Universidad de Medellin, Carrera 87 No. 30-65, Medellin (Colombia)

    2013-06-10

    Magnetic protection of potentially habitable planets plays a central role in determining their actual habitability and/or the chances of detecting atmospheric biosignatures. Here we develop a thermal evolution model of potentially habitable Earth-like planets and super-Earths (SEs). Using up-to-date dynamo-scaling laws, we predict the properties of core dynamo magnetic fields and study the influence of thermal evolution on their properties. The level of magnetic protection of tidally locked and unlocked planets is estimated by combining simplified models of the planetary magnetosphere and a phenomenological description of the stellar wind. Thermal evolution introduces a strong dependence of magnetic protection on planetary mass and rotation rate. Tidally locked terrestrial planets with an Earth-like composition would have early dayside magnetopause distances between 1.5 and 4.0 R{sub p} , larger than previously estimated. Unlocked planets with periods of rotation {approx}1 day are protected by magnetospheres extending between 3 and 8 R{sub p} . Our results are robust in comparison with variations in planetary bulk composition and uncertainties in other critical model parameters. For illustration purposes, the thermal evolution and magnetic protection of the potentially habitable SEs GL 581d, GJ 667Cc, and HD 40307g were also studied. Assuming an Earth-like composition, we found that the dynamos of these planets are already extinct or close to being shut down. While GL 581d is the best protected, the protection of HD 40307g cannot be reliably estimated. GJ 667Cc, even under optimistic conditions, seems to be severely exposed to the stellar wind, and, under the conditions of our model, has probably suffered massive atmospheric losses.

  11. THE INFLUENCE OF PRESSURE-DEPENDENT VISCOSITY ON THE THERMAL EVOLUTION OF SUPER-EARTHS

    Energy Technology Data Exchange (ETDEWEB)

    Stamenkovic, Vlada; Noack, Lena; Spohn, Tilman [Institute of Planetology, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Breuer, Doris, E-mail: Vlada.Stamenkovic@dlr.de, E-mail: Lena.Noack@dlr.de, E-mail: Doris.Breuer@dlr.de, E-mail: Tilman.Spohn@dlr.de [Institute of Planetary Research, German Aerospace Center DLR, Rutherfordstrasse 2, 12489 Berlin (Germany)

    2012-03-20

    We study the thermal evolution of super-Earths with a one-dimensional (1D) parameterized convection model that has been adopted to account for a strong pressure dependence of the viscosity. A comparison with a 2D spherical convection model shows that the derived parameterization satisfactorily represents the main characteristics of the thermal evolution of massive rocky planets. We find that the pressure dependence of the viscosity strongly influences the thermal evolution of super-Earths-resulting in a highly sluggish convection regime in the lower mantles of those planets. Depending on the effective activation volume and for cooler initial conditions, we observe with growing planetary mass even the formation of a conductive lid above the core-mantle boundary (CMB), a so-called CMB-lid. For initially molten planets our results suggest no CMB-lids but instead a hot lower mantle and core as well as sluggish lower mantle convection. This implies that the initial interior temperatures, especially in the lower mantle, become crucial for the thermal evolution-the thermostat effect suggested to regulate the interior temperatures in terrestrial planets does not work for massive planets if the viscosity is strongly pressure dependent. The sluggish convection and the potential formation of the CMB-lid reduce the convective vigor throughout the mantle, thereby affecting convective stresses, lithospheric thicknesses, and heat fluxes. The pressure dependence of the viscosity may therefore also strongly affect the propensity of plate tectonics, volcanic activity, and the generation of a magnetic field of super-Earths.

  12. Imitation, genetic lineages, and time influenced the morphological evolution of the violin.

    Science.gov (United States)

    Chitwood, Daniel H

    2014-01-01

    Violin design has been in flux since the production of the first instruments in 16th century Italy. Numerous innovations have improved the acoustical properties and playability of violins. Yet, other attributes of the violin affect its performance less, and with fewer constraints, are potentially more sensitive to historical vagaries unrelated to quality. Although the coarse shape of violins is integral to their design, details of the body outline can vary without significantly compromising sound quality. What can violin shapes tell us about their makers and history, including the degree that luthiers have influenced each other and the evolution of complex morphologies over time? Here, I provide an analysis of morphological evolution in the violin family, sampling the body shapes of over 9,000 instruments over 400 years of history. Specific shape attributes, which discriminate instruments produced by different luthiers, strongly correlate with historical time. Linear discriminant analysis reveals luthiers who likely copied the outlines of their instruments from others, which historical accounts corroborate. Clustering of averaged violin shapes places luthiers into four major groups, demonstrating a handful of discrete shapes predominate in most instruments. Violin shapes originating from multi-generational luthier families tend to cluster together, and familial origin is a significant explanatory factor of violin shape. Together, the analysis of four centuries of violin shapes demonstrates not only the influence of history and time leading to the modern violin, but widespread imitation and the transmission of design by human relatedness.

  13. Imitation, genetic lineages, and time influenced the morphological evolution of the violin.

    Directory of Open Access Journals (Sweden)

    Daniel H Chitwood

    Full Text Available Violin design has been in flux since the production of the first instruments in 16th century Italy. Numerous innovations have improved the acoustical properties and playability of violins. Yet, other attributes of the violin affect its performance less, and with fewer constraints, are potentially more sensitive to historical vagaries unrelated to quality. Although the coarse shape of violins is integral to their design, details of the body outline can vary without significantly compromising sound quality. What can violin shapes tell us about their makers and history, including the degree that luthiers have influenced each other and the evolution of complex morphologies over time? Here, I provide an analysis of morphological evolution in the violin family, sampling the body shapes of over 9,000 instruments over 400 years of history. Specific shape attributes, which discriminate instruments produced by different luthiers, strongly correlate with historical time. Linear discriminant analysis reveals luthiers who likely copied the outlines of their instruments from others, which historical accounts corroborate. Clustering of averaged violin shapes places luthiers into four major groups, demonstrating a handful of discrete shapes predominate in most instruments. Violin shapes originating from multi-generational luthier families tend to cluster together, and familial origin is a significant explanatory factor of violin shape. Together, the analysis of four centuries of violin shapes demonstrates not only the influence of history and time leading to the modern violin, but widespread imitation and the transmission of design by human relatedness.

  14. Evolution of dislocation structures following a change in loading conditions studied by in situ high resolution reciprocal space mapping

    DEFF Research Database (Denmark)

    Wejdemann, Christian

    or to a strain of 7% at a temperature of -196 ○C, and the samples were characterized by electron microscopy and mechanical tests. Transmission electron microscopy showed that the pre-deformation produced a characteristic dislocation cell structure consisting of regions with relatively high dislocation density...... the pre-deformation axis. In the X-ray diffraction experiments a technique was employed with which it is possible to obtain high-resolution reciprocal space maps from individual bulk grains. The high-resolution reciprocal space maps contain features related to the dislocation structure in the grains......: A spread-out ‘cloud’ of low intensity caused by diffraction from the dislocation walls and a number of sharp peaks of high intensity caused by diffraction from the individual subgrains. By acquiring reciprocal space maps at a number of different strain levels the evolution of the dislocation structures can...

  15. Earth Regimes Network Evolution Study (ERNESt): Introducing the Space Mobile Network

    Science.gov (United States)

    Menrad, Bob

    2016-01-01

    Speaker and Presenter at the Lincoln Laboratory Communications Workshop on April 5, 2016 at the Massachusetts Institute of Technology Lincoln Laboratory in Lexington, MA. A visual presentation titled Earth Regimes Network Evolution Study (ERNESt).

  16. Solving QCD evolution equations in rapidity space with Markovian Monte Carlo

    CERN Document Server

    Golec-Biernat, K; Placzek, W; Skrzypek, M

    2009-01-01

    This work covers methodology of solving QCD evolution equation of the parton distribution using Markovian Monte Carlo (MMC) algorithms in a class of models ranging from DGLAP to CCFM. One of the purposes of the above MMCs is to test the other more sophisticated Monte Carlo programs, the so-called Constrained Monte Carlo (CMC) programs, which will be used as a building block in the parton shower MC. This is why the mapping of the evolution variables (eikonal variable and evolution time) into four-momenta is also defined and tested. The evolution time is identified with the rapidity variable of the emitted parton. The presented MMCs are tested independently, with ~0.1% precision, against the non-MC program APCheb especially devised for this purpose.

  17. Determining selection across heterogeneous landscapes: a perturbation-based method and its application to modeling evolution in space

    OpenAIRE

    Wickman, J.; Diehl, S.; Blasius, B.; Klausmeier, C.; Ryabov, A.; Brännström, Å.

    2017-01-01

    Spatial structure can decisively influence the way evolutionary processes unfold. Several methods have thus far been used to study evolution in spatial systems, including population genetics, quantitative genetics, momentclosure approximations, and individual-based models. Here we extend the study of spatial evolutionary dynamics to eco-evolutionary models based on reaction-diffusion equations and adaptive dynamics. Specifically, we derive expressions for the strength of directional and stabi...

  18. Tool for evaluating the evolution Space Weather Regional Warning Centers under the innovation point of view: the Case Study of the Embrace Space Weather Program Early Stages

    Science.gov (United States)

    Denardini, Clezio Marcos

    2016-07-01

    We have developed a tool for measuring the evolutional stage of the space weather regional warning centers using the approach of the innovative evolution starting from the perspective presented by Figueiredo (2009, Innovation Management: Concepts, metrics and experiences of companies in Brazil. Publisher LTC, Rio de Janeiro - RJ). It is based on measuring the stock of technological skills needed to perform a certain task that is (or should) be part of the scope of a space weather center. It also addresses the technological capacity for innovation considering the accumulation of technological and learning capabilities, instead of the usual international indices like number of registered patents. Based on this definition, we have developed a model for measuring the capabilities of the Brazilian Study and Monitoring Program Space Weather (Embrace), a program of the National Institute for Space Research (INPE), which has gone through three national stages of development and an international validation step. This program was created in 2007 encompassing competence from five divisions of INPE in order to carry out the data collection and maintenance of the observing system in space weather; to model processes of the Sun-Earth system; to provide real-time information and to forecast space weather; and provide diagnostic their effects on different technological systems. In the present work, we considered the issues related to the innovation of micro-processes inherent to the nature of the Embrace program, not the macro-economic processes, despite recognizing the importance of these. During the development phase, the model was submitted to five scientists/managers from five different countries member of the International Space Environment Service (ISES) who presented their evaluations, concerns and suggestions. It was applied to the Embrace program through an interview form developed to be answered by professional members of regional warning centers. Based on the returning

  19. THE INFLUENCE OF PRESSURE-DEPENDENT VISCOSITY ON THE THERMAL EVOLUTION OF SUPER-EARTHS

    International Nuclear Information System (INIS)

    Stamenković, Vlada; Noack, Lena; Spohn, Tilman; Breuer, Doris

    2012-01-01

    We study the thermal evolution of super-Earths with a one-dimensional (1D) parameterized convection model that has been adopted to account for a strong pressure dependence of the viscosity. A comparison with a 2D spherical convection model shows that the derived parameterization satisfactorily represents the main characteristics of the thermal evolution of massive rocky planets. We find that the pressure dependence of the viscosity strongly influences the thermal evolution of super-Earths—resulting in a highly sluggish convection regime in the lower mantles of those planets. Depending on the effective activation volume and for cooler initial conditions, we observe with growing planetary mass even the formation of a conductive lid above the core-mantle boundary (CMB), a so-called CMB-lid. For initially molten planets our results suggest no CMB-lids but instead a hot lower mantle and core as well as sluggish lower mantle convection. This implies that the initial interior temperatures, especially in the lower mantle, become crucial for the thermal evolution—the thermostat effect suggested to regulate the interior temperatures in terrestrial planets does not work for massive planets if the viscosity is strongly pressure dependent. The sluggish convection and the potential formation of the CMB-lid reduce the convective vigor throughout the mantle, thereby affecting convective stresses, lithospheric thicknesses, and heat fluxes. The pressure dependence of the viscosity may therefore also strongly affect the propensity of plate tectonics, volcanic activity, and the generation of a magnetic field of super-Earths.

  20. Keeping you at arm's length: modifying peripersonal space influences interpersonal distance.

    Science.gov (United States)

    Quesque, F; Ruggiero, G; Mouta, S; Santos, J; Iachini, T; Coello, Y

    2017-07-01

    Peripersonal space represents the area around the body where objects are coded in motor terms for the purpose of voluntary goal-directed actions. Previous studies have suggested that peripersonal space is also a safe space linked with our private area, influencing interpersonal space in social contexts. However, whether these two spaces rely on similar embodied processes remains an open issue. In the present study, participants observed a point-light walker (PLW) approaching them from different directions and passing near them at different distances from their right or left shoulder. While approaching, the PLW disappeared at a distance of 2 m and the task for the participants was to estimate if the interpersonal distance, at the time the PLW would have reached their level, was comfortable or not. Between two sessions of comfort judgments, the participants manipulated a 70 cm tool entailing an extension of peripersonal space, or a 10 cm tool entailing no extension of peripersonal space. The results revealed that the comfortable interpersonal distance was larger when the PLW crossed the mid-sagittal plane of the participants than when it approached them laterally, with a concomitant increase of response time. After participants manipulated the long tool, comfortable interpersonal distance increased, but predominantly when the PLW trajectory implied crossing the participants' mid-sagittal plane. This effect was not observed when participants manipulated the short tool. Two control tasks showed that using the long tool modified the reachability (control 1), but not the time to passage (control 2) estimates of PLW stimuli, suggesting that tool use extended peripersonal space without changing perceived visual distances. Overall, the data show that comfortable interpersonal distance is linked to the representation of peripersonal space. As a consequence, increasing peripersonal space through tool use has the immediate consequence that comfortable interpersonal distance

  1. THE INFLUENCE OF RADIAL STELLAR MIGRATION ON THE CHEMICAL EVOLUTION OF THE MILKY WAY

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yue; Zhao Gang, E-mail: gzhao@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-05-20

    Stellar migration is an important dynamical process in the Galactic disk. Here we model radial stellar migration in the Galactic disk with an analytical method, then add it to a detailed Galactic chemical evolution model to study the influence of radial stellar migration on the chemical evolution of the Milky Way, especially for the abundance gradients. We found that the radial stellar migration in the Galactic disk can make the profile of the G-dwarf metallicity distribution of the solar neighborhood taller and narrower, and thus it becomes another solution to the ''G-dwarf problem''. It can also scatter the age-metallicity relation. However, after migration, the abundance distributions along the Galactic radius do not change much; namely, the abundance gradients would not be flattened by the radial stellar migration, which is different from the predictions of many theoretical works. However, it can flatten the radial gradients of the mean chemical abundance of stars, and older stars possess flatter abundance gradients than younger stars. The most significant effect of radial stellar migration on the chemical abundance is that at a certain position it scatters the abundance of stars from a relatively concentrated value to a range.

  2. Influence of Adsorbed Water on the Oxygen Evolution Reaction on Oxides

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Vojvodic, Aleksandra

    2015-01-01

    We study the interface between adsorbed water and stoichiometric, defect-free (110) rutile oxide surfaces of TiO2, RuO2, and IrO2 in order to understand how water influences the stabilities of the intermediates of the oxygen evolution reaction (OER). In our model the water is treated as explicitly...... molecules binding to bridging oxygens. The third chain interacts weakly and predominantly with the H2O molecules of the second layer, resembling bulk water. We find that the stability of the water layer close to the oxide surface is almost the same as the one found on flat metal surfaces, such as the Pt(111...... of RuO2 and IrO2, while it is increased by similar to 0.4 eV for TiO2....

  3. Solar rotation and activity in the past and their possible influence upon the evolution of life

    International Nuclear Information System (INIS)

    Geyer, E.H.

    1981-01-01

    It is proposed that the rotational angular momentum of the lower Main Sequence stars determines the intensity of their magnetic spot activity. As a consequence of this feedback coupling, the stellar rotation and the activity decay exponentially by magnetic braking of the induced stellar flare- and wind-activity. Therefore, the Sun should have rotated much faster and must have shown a very enhanced activity in its early history. This strong solar activity in the past could have influenced the evolution of terrestrial life, and may explain the stagnation of maritime life for about 2 x 10 9 yr, the diversification of species during the Cambrian formation, and the land conquest by life in the upper Silurian system. (Auth.)

  4. Solar rotation and activity in the past and their possible influence upon the evolution of life

    Energy Technology Data Exchange (ETDEWEB)

    Geyer, E H [Bonn Univ. (Germany, F.R.). Sternwarte

    1981-06-01

    It is proposed that the rotational angular momentum of the lower Main Sequence stars determines the intensity of their magnetic spot activity. As a consequence of this feedback coupling, the stellar rotation and the activity decay exponentially by magnetic braking of the induced stellar flare- and wind-activity. Therefore, the Sun should have rotated much faster and must have shown a very enhanced activity in its early history. This strong solar activity in the past could have influenced the evolution of terrestrial life, and may explain the stagnation of maritime life for about 2 x 10/sup 9/ yr, the diversification of species during the Cambrian formation, and the land conquest by life in the upper Silurian system.

  5. Urban Public Space Context and Cognitive Psychology Evolution in Information Environment

    Science.gov (United States)

    Feng, Chen; Xu, Hua-wei

    2017-11-01

    The rapid development of information technology has had a great impact on the understanding of urban environment, which brings different spatially psychological experience. Information and image transmission has been full with the streets, both the physical space and virtual space have been unprecedentedly blended together through pictures, images, electronic media and other tools, which also stimulates people’s vision and psychology and gives birth to a more complex form of urban space. Under the dual role of spatial mediumlization and media spatialization, the psychological cognitive pattern of urban public space context is changing.

  6. The influence of row width and seed spacing on uniformity of plant spatial distributions

    DEFF Research Database (Denmark)

    Griepentrog, Hans W.; Olsen, Jannie Maj; Weiner, Jacob

    2009-01-01

    width and evenness of spacing within rows influences two-dimensional spatial quality. The results can be used to define new requirements for improved seeding technologies to achieve higher benefits in sustainable crop production systems. In general it can be concluded that more even plant distributions...... are expected to result in a better crop plant performance....

  7. Influence of cusps and intersections on the Wilson loop in ν-dimensional space

    International Nuclear Information System (INIS)

    Bezerra, V.B.

    1984-01-01

    A discussion is given about the influence of cusps and intersections on the calculation of the Wilson loop in ν-dimensional space. In particular, for the two-dimensional case, it is shown that there are no divergences. (Author) [pt

  8. Safety of information in electronic equipment influenced by the charged space particles

    Directory of Open Access Journals (Sweden)

    Ksenia Gennad’evna Sizova

    2016-10-01

    Full Text Available A version of the existing evaluation method of electronic equipment to the influence of charged space particles causing single event effects for the purpose of improving the accuracy of calculation in the field of information safety is suggested. On the basis of the existing and modified methods radiation tolerance of real payload spacecraft responsible for the security of transmitted information are defined. The results of comparison are introduced. Significant differences not only in quantitative but also in qualitative character of tolerance indicators are revealed. It is demonstrated that the modified method allows to take into account the functional complexity of the hardware and the application efficiency of the sophisticated single event effects protection tools. To confirm the applicability of the modified method of equipment tolerance evaluation method to the influence of charged space particles causing single event effects proposals to the procedure of ground tests of the payload and the space experiment are developed.

  9. From Commons to Classroom: The Evolution of Learning Spaces in Academic Libraries

    Science.gov (United States)

    Karasic, Victoria

    2016-01-01

    Over the past two decades, academic library spaces have evolved to meet the changing teaching and learning needs of diverse campus communities. The Information Commons combines the physical and virtual in an informal library space, whereas the recent Active Learning Classroom creates a more formal setting for collaboration. As scholarship has…

  10. Pseudo-Newtonian Equations for Evolution of Particles and Fluids in Stationary Space-times

    Energy Technology Data Exchange (ETDEWEB)

    Witzany, Vojtěch; Lämmerzahl, Claus, E-mail: vojtech.witzany@zarm.uni-bremen.de, E-mail: claus.laemmerzahl@zarm.uni-bremen.de [ZARM, Universität Bremen, Am Fallturm, D-28359 Bremen (Germany)

    2017-06-01

    Pseudo-Newtonian potentials are a tool often used in theoretical astrophysics to capture some key features of a black hole space-time in a Newtonian framework. As a result, one can use Newtonian numerical codes, and Newtonian formalism, in general, in an effective description of important astrophysical processes such as accretion onto black holes. In this paper, we develop a general pseudo-Newtonian formalism, which pertains to the motion of particles, light, and fluids in stationary space-times. In return, we are able to assess the applicability of the pseudo-Newtonian scheme. The simplest and most elegant formulas are obtained in space-times without gravitomagnetic effects, such as the Schwarzschild rather than the Kerr space-time; the quantitative errors are smallest for motion with low binding energy. Included is a ready-to-use set of fluid equations in Schwarzschild space-time in Cartesian and radial coordinates.

  11. The evolution of conceptions about space and time in literary theory

    Directory of Open Access Journals (Sweden)

    Lazić Nebojša J.

    2012-01-01

    Full Text Available This work considers the function of space and time in poetics of literary text from the antique period till the theory of deconstruction as well as from Aristotle till Jacques Derrida and Paul de Man. The science of literature did not equally treat the problem of space and the problem of time as the elements of the literary work's structure. Disbalance presents the damage of studying the space because there is a significant number of monographs about time. Since the categories of space and time are the areas of studying physical and spiritual sciences, it was necessary to pay attention to considering these questions in exact sciences such as Physics, Maths etc. Further development of the science of literature is not possible without describing the role of space and time in writing and shaping a literary text. .

  12. Public Space in Barcelona (1992-2017) - Evolution and Case Studies

    Science.gov (United States)

    Sanfeliu Arboix, Ignacio; Martín, Estefanía

    2017-10-01

    The construction of the public space has become in the last decades something so important and fundamental in the architecture of the cities, that requires a specific discipline and a concrete study that evaluates the characteristics and actions on it. Not already from an urbanistic perspective but from its own design and constructive perspective, with its character as a place for everyone and for everything, must gather a series of elements that are unique to this space. Barcelona is one of the densest cities in the world that, since the end of the s. XX until our days, tries to solve the public space with a design of quality and optimum. The shortage of public space, which also hosts more than eight million tourists each year, makes it necessary to propose a type of meticulous intervention in order to accommodate all types of users and activities. From the first Universal Exhibition of 1888 through 1929 to the 1992 Olympics as the most important stimulus for this renewal of urban space, Barcelona has been rethinking and evolving in the modus operandi in terms of its urban space. From our professional experience as architects both in the municipal, private and university spheres, we believe that it is our responsibility to confer the public space, that is to say, the design of the urban infrastructure with the attributes necessary to consolidate it in a space Suitable for all without exception and as a place of expression of citizenship. Through the projects of public space developed in our office we will analyze this change of procedure in the construction of squares, parks and other spaces in the city of Barcelona.

  13. Synthetic biology for the directed evolution of protein biocatalysts: navigating sequence space intelligently

    Science.gov (United States)

    Currin, Andrew; Swainston, Neil; Day, Philip J.

    2015-01-01

    The amino acid sequence of a protein affects both its structure and its function. Thus, the ability to modify the sequence, and hence the structure and activity, of individual proteins in a systematic way, opens up many opportunities, both scientifically and (as we focus on here) for exploitation in biocatalysis. Modern methods of synthetic biology, whereby increasingly large sequences of DNA can be synthesised de novo, allow an unprecedented ability to engineer proteins with novel functions. However, the number of possible proteins is far too large to test individually, so we need means for navigating the ‘search space’ of possible protein sequences efficiently and reliably in order to find desirable activities and other properties. Enzymologists distinguish binding (K d) and catalytic (k cat) steps. In a similar way, judicious strategies have blended design (for binding, specificity and active site modelling) with the more empirical methods of classical directed evolution (DE) for improving k cat (where natural evolution rarely seeks the highest values), especially with regard to residues distant from the active site and where the functional linkages underpinning enzyme dynamics are both unknown and hard to predict. Epistasis (where the ‘best’ amino acid at one site depends on that or those at others) is a notable feature of directed evolution. The aim of this review is to highlight some of the approaches that are being developed to allow us to use directed evolution to improve enzyme properties, often dramatically. We note that directed evolution differs in a number of ways from natural evolution, including in particular the available mechanisms and the likely selection pressures. Thus, we stress the opportunities afforded by techniques that enable one to map sequence to (structure and) activity in silico, as an effective means of modelling and exploring protein landscapes. Because known landscapes may be assessed and reasoned about as a whole

  14. Neutral evolution of proteins: The superfunnel in sequence space and its relation to mutational robustness

    Science.gov (United States)

    Noirel, Josselin; Simonson, Thomas

    2008-11-01

    Following Kimura's neutral theory of molecular evolution [M. Kimura, The Neutral Theory of Molecular Evolution (Cambridge University Press, Cambridge, 1983) (reprinted in 1986)], it has become common to assume that the vast majority of viable mutations of a gene confer little or no functional advantage. Yet, in silico models of protein evolution have shown that mutational robustness of sequences could be selected for, even in the context of neutral evolution. The evolution of a biological population can be seen as a diffusion on the network of viable sequences. This network is called a "neutral network." Depending on the mutation rate μ and the population size N, the biological population can evolve purely randomly (μN ≪1) or it can evolve in such a way as to select for sequences of higher mutational robustness (μN ≫1). The stringency of the selection depends not only on the product μN but also on the exact topology of the neutral network, the special arrangement of which was named "superfunnel." Even though the relation between mutation rate, population size, and selection was thoroughly investigated, a study of the salient topological features of the superfunnel that could affect the strength of the selection was wanting. This question is addressed in this study. We use two different models of proteins: on lattice and off lattice. We compare neutral networks computed using these models to random networks. From this, we identify two important factors of the topology that determine the stringency of the selection for mutationally robust sequences. First, the presence of highly connected nodes ("hubs") in the network increases the selection for mutationally robust sequences. Second, the stringency of the selection increases when the correlation between a sequence's mutational robustness and its neighbors' increases. The latter finding relates a global characteristic of the neutral network to a local one, which is attainable through experiments or molecular

  15. Evolution of High Intensity Beams in the CERN PS Booster after H⁻ Injection and Phase Space Painting

    CERN Document Server

    Cieslak-Kowalska, Magdalena; Benedetto, Elena; Bracco, Chiara

    2016-01-01

    With the LHC Injector Upgrade (LIU) project, the injection energy of PS Booster (PSB) ' first circular accelerator in the LHC injector chain ' will be raised from 50 MeV to 160 MeV and the present multiturn injection will be upgraded to H⁻ injection with transverse and longitudinal painting. In the scope of this project, it is planned to double the beam intensities, profiting from the fact that the βγ2 factor will be two times larger (0.35 at 50 MeV and 0.71 at 160 MeV), so the resulting tune spread driven by a direct space charge should remain similar. This paper describes the feasibility to double the intensity of high intensity and large emittance beams, looking into the evolution under space charge and taking into account losses constrains in the ring and in the extraction lines.

  16. The Evolution of Failure Analysis at NASA's Kennedy Space Center and the Lessons Learned

    Science.gov (United States)

    Long, Victoria S.; Wright, M. Clara; McDanels, Steve

    2015-01-01

    The United States has had four manned launch programs and three station programs since the era of human space flight began in 1961. The launch programs, Mercury, Gemini, Apollo, and Shuttle, and the station programs, Skylab, Shuttle-Mir, and the International Space Station (ISS), have all been enormously successful, not only in advancing the exploration of space, but also in advancing related technologies. As each subsequent program built upon the successes of previous programs, they similarly learned from their predecessors' failures. While some failures were spectacular and captivated the attention of the world, most only held the attention of the dedicated men and women working to make the missions succeed.

  17. Exploring the Birth and Evolution of the Universe: How Detectors Have Revolutionized Space Astronomy

    Science.gov (United States)

    Moseley, Samuel H.

    2012-01-01

    The past century has seen tremendous advances in the capability of instruments used for astronomical imaging and spectroscopy. Capabilities of instruments have expanded in many dimensions; the scale of telescopes has grown tremendously, the wavelengths used for astronomy have grown from visible light to the full electromagnetic spectrum, extending from gamma rays to low frequency radio waves. Additional advances have been enabled by the availability of space facilities, which eliminate the effects of the earths atmosphere and magnetosphere, and allow cooling of instruments to avoid instrumental thermal radiation. Even with all these advances, the increase in capability of detection systems has produced truly revolutionary improvements in capability. Today, I will describe the advances in astronomical detection from the photographic plates of the early 20th century to the giant high efficiency focal planes being developed for modern space and ground based astronomical instrument. I will review the demanding performance requirements set by space astronomy, and show how the detector community has risen to the challenge in producing high performance detectors for the Hubble Space Telescope, the Spitzer Space Telescope, and the James Webb Space Telescope, now under development.

  18. A Long-Term Space Astrophysics Research Program. The Evolution of the Quasar Continuum

    Science.gov (United States)

    Elvis, M.

    1998-01-01

    The grant "The Evolution of the Quasar Continuum" resulted in over 53 published referred papers and conference proceedings. The more significant of these papers are listed below, and abstracts are attached. The papers address a wide range of issues involving the evolution of quasars, their electromagnetic emissions, and their environment, from nearby low luminosity Seyfert galaxies to quasars at the highest redshifts. Primarily observational in content the work nonetheless included theoretical studies of quasar accretion disks that attempt to explain the observed time variability of quasars, and the overall 'demographics' of the quasar population. The work carried out under this grant has laid a strong foundation for ongoing and future research with AXAF, HST and other new facilities.

  19. Memory matters: influence from a cognitive map on animal space use.

    Science.gov (United States)

    Gautestad, Arild O

    2011-10-21

    A vertebrate individual's cognitive map provides a capacity for site fidelity and long-distance returns to favorable patches. Fractal-geometrical analysis of individual space use based on collection of telemetry fixes makes it possible to verify the influence of a cognitive map on the spatial scatter of habitat use and also to what extent space use has been of a scale-specific versus a scale-free kind. This approach rests on a statistical mechanical level of system abstraction, where micro-scale details of behavioral interactions are coarse-grained to macro-scale observables like the fractal dimension of space use. In this manner, the magnitude of the fractal dimension becomes a proxy variable for distinguishing between main classes of habitat exploration and site fidelity, like memory-less (Markovian) Brownian motion and Levy walk and memory-enhanced space use like Multi-scaled Random Walk (MRW). In this paper previous analyses are extended by exploring MRW simulations under three scenarios: (1) central place foraging, (2) behavioral adaptation to resource depletion (avoidance of latest visited locations) and (3) transition from MRW towards Levy walk by narrowing memory capacity to a trailing time window. A generalized statistical-mechanical theory with the power to model cognitive map influence on individual space use will be important for statistical analyses of animal habitat preferences and the mechanics behind site fidelity and home ranges. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Creating and Exploring Huge Parameter Spaces: Interactive Evolution as a Tool for Sound Generation

    DEFF Research Database (Denmark)

    Dahlstedt, Palle

    2001-01-01

    In this paper, a program is presented that applies interactive evolution to sound generation, i.e., preferred individuals are repeatedly selected from a population of genetically bred sound objects, created with various synthesis and pattern generation algorithms. This simplifies aural exploration...... applications. It is also shown how this technique can be used to simplify sound design in standard hardware synthesizers, a task normally avoided by most musicians, due to the required amount of technical understanding....

  1. The influence of international and domestic events in the evolution of forest inventory and reporting consistency in the United States

    Science.gov (United States)

    W. Brad Smith

    2009-01-01

    This article takes a brief chronological look at resource inventory and reporting and links to international influences. It explores events as drivers of more consistent data within the United States and highlights key dates and events in the evolution of inventory policy and practice. From King George to L?Ecole nationale forestiere to the Food and Agriculture...

  2. On the influence of hydronium and hydroxide ion diffusion on the hydrogen and oxygen evolution reactions in aqueous media

    DEFF Research Database (Denmark)

    Wiberg, Gustav Karl Henrik; Arenz, Matthias

    2015-01-01

    We present a study concerning the influence of the diffusion of H+ and OH- ions on the hydrogen and oxygen evolution reactions (HER and OER) in aqueous electrolyte solutions. Using a rotating disk electrode (RDE), it is shown that at certain conditions the observed current, i.e., the reaction rate...

  3. Conceptual Ecology of the Evolution Acceptance among Greek Education Students: Knowledge, Religious Practices and Social Influences

    Science.gov (United States)

    Athanasiou, Kyriacos; Papadopoulou, Penelope

    2012-01-01

    In this study, we explored some of the factors related to the acceptance of evolution theory among Greek university students training to be teachers in early childhood education, using conceptual ecology for biological evolution as a theoretical framework. We examined the acceptance of evolution theory and we also looked into the relationship…

  4. Study of influence of climber motion on the space elevator dynamics

    Directory of Open Access Journals (Sweden)

    A. S. Ledkov

    2014-01-01

    Full Text Available The operation of launching a payload into orbit by means of a space elevator is considered in this paper. The space elevator is a mechanical system that consists of a tether, a space station, and a climber. The tether connects the surface of the Earth with the space station, which is above the geostationary orbit. The climber lifts the payload to the required altitude. Then it is disconnected from the space elevator and starts free orbital flight. Creation of the space elevator will significantly reduce the cost of payloads delivery to orbit.The objective of this work is to study dynamics of the space elevator taking into account the climber motion. A mathematical model, which takes into consideration bending of the tether and features of the climber construction, is developed. In contrast to existing models, the climber is considered not as a mass point, but as a mechanical system consisting of two homogeneous weighty cylinders connected by a weightless strap upon which the payload is located. The payload and the space stations are considered as mass points. The tether is simulated as a pair of inelastic inextensible bars with variable length. The area of bars cross-sections is defined by a function, which depends on the distance to the end of the bars. Motion occurs in the equatorial plane in the gravitational field of the Earth.It is shown that lifting of the climber leads to swinging of the space elevator in the equatorial plane. This effect is caused by the influence of Coriolis forces of inertia. After stopping of the climber the space elevator oscillates about the vertical. An effect of the payload mass on amplitude of the space elevator oscillation is studied. It is shown that the increasing payload mass leads to the growing amplitude of the space elevator oscillations. A control torque providing steady lifting of the payload is obtained. The results of the calculations show that the practical implementation of the space elevator

  5. Persistence of solutions to nonlinear evolution equations in weighted Sobolev spaces

    Directory of Open Access Journals (Sweden)

    Xavier Carvajal Paredes

    2010-11-01

    Full Text Available In this article, we prove that the initial value problem associated with the Korteweg-de Vries equation is well-posed in weighted Sobolev spaces $mathcal{X}^{s,heta}$, for $s geq 2heta ge 2$ and the initial value problem associated with the nonlinear Schrodinger equation is well-posed in weighted Sobolev spaces $mathcal{X}^{s,heta}$, for $s geq heta geq 1$. Persistence property has been proved by approximation of the solutions and using a priori estimates.

  6. End-to-end simulations and planning of a small space telescopes: Galaxy Evolution Spectroscopic Explorer: a case study

    Science.gov (United States)

    Heap, Sara; Folta, David; Gong, Qian; Howard, Joseph; Hull, Tony; Purves, Lloyd

    2016-08-01

    Large astronomical missions are usually general-purpose telescopes with a suite of instruments optimized for different wavelength regions, spectral resolutions, etc. Their end-to-end (E2E) simulations are typically photons-in to flux-out calculations made to verify that each instrument meets its performance specifications. In contrast, smaller space missions are usually single-purpose telescopes, and their E2E simulations start with the scientific question to be answered and end with an assessment of the effectiveness of the mission in answering the scientific question. Thus, E2E simulations for small missions consist a longer string of calculations than for large missions, as they include not only the telescope and instrumentation, but also the spacecraft, orbit, and external factors such as coordination with other telescopes. Here, we illustrate the strategy and organization of small-mission E2E simulations using the Galaxy Evolution Spectroscopic Explorer (GESE) as a case study. GESE is an Explorer/Probe-class space mission concept with the primary aim of understanding galaxy evolution. Operation of a small survey telescope in space like GESE is usually simpler than operations of large telescopes driven by the varied scientific programs of the observers or by transient events. Nevertheless, both types of telescopes share two common challenges: maximizing the integration time on target, while minimizing operation costs including communication costs and staffing on the ground. We show in the case of GESE how these challenges can be met through a custom orbit and a system design emphasizing simplification and leveraging information from ground-based telescopes.

  7. Evolution from pure states into mixed states in de Sitter space

    International Nuclear Information System (INIS)

    Sakagami, Masa-aki.

    1987-03-01

    An attempt is made to clarify realization of a classical distribution from quantum fluctuations of the order parameter in the inflationary universe. We discuss destruction of quantum coherence associated with a state of the order parameter in models where it interacts with the environment. For that purpose, the time evolution of the reduced density matrix ρ tilde, which is obtained by coarse-graining of the environment, is investigated. It is shown that off-diagonal elements of ρ tilde decrease as the phase transition proceeds. (author)

  8. On evolution of small spheres in the phase space of a dynamical system*

    Directory of Open Access Journals (Sweden)

    Komech Sergei

    2012-08-01

    Full Text Available We study the connection between the entropy of a dynamical system and the boundary distortion rate of regions in the phase space of the system. Nous étudions la connexion entre l’entropie d’un système dynamique et le taux de distortion au bord dans l’espace des phases du système.

  9. Computer-automated evolution of an X-band antenna for NASA's Space Technology 5 mission.

    Science.gov (United States)

    Hornby, Gregory S; Lohn, Jason D; Linden, Derek S

    2011-01-01

    Whereas the current practice of designing antennas by hand is severely limited because it is both time and labor intensive and requires a significant amount of domain knowledge, evolutionary algorithms can be used to search the design space and automatically find novel antenna designs that are more effective than would otherwise be developed. Here we present our work in using evolutionary algorithms to automatically design an X-band antenna for NASA's Space Technology 5 (ST5) spacecraft. Two evolutionary algorithms were used: the first uses a vector of real-valued parameters and the second uses a tree-structured generative representation for constructing the antenna. The highest-performance antennas from both algorithms were fabricated and tested and both outperformed a hand-designed antenna produced by the antenna contractor for the mission. Subsequent changes to the spacecraft orbit resulted in a change in requirements for the spacecraft antenna. By adjusting our fitness function we were able to rapidly evolve a new set of antennas for this mission in less than a month. One of these new antenna designs was built, tested, and approved for deployment on the three ST5 spacecraft, which were successfully launched into space on March 22, 2006. This evolved antenna design is the first computer-evolved antenna to be deployed for any application and is the first computer-evolved hardware in space.

  10. Evolution of Spaces between Buildings in Polish Mass Housing Estates in the Eyes of the Inhabitants

    Science.gov (United States)

    Ostanska, Anna

    2017-10-01

    The author investigates into the state of public and semi-public spaces in the Polish housing estates erected in the times of mass housing projects (1960 - 1980). The character of these estates is special. On the one hand, the buildings were accompanied by lavishly designed open spaces with elaborate material infrastructure: urban design followed the ideas that time - and strict regulations - that, in theory, prevented creation of substandard spaces. Provision of affordable housing was given a priority in the centrally controlled economy, so vast greenfield areas were devoted to housing. Moreover, the estates often stay under one management of housing cooperatives for years. The assets are relatively modern and usually conveniently located within the city/town infrastructure. This gives the areas advantage over contemporary housing schemes affected by constraints imposed by prior development and commercial approach to the provision of housing. On the other hand, technical wear and tear, functional obsolescence, years of underinvestment, natural demographic changes in local communities, changing ownership structure, and weakening social bonds make the large housing estates with their too lavishly designed public areas an ungrateful object of management. Recent availability of the European Union funds for modernization of public spaces increases the numbers of municipal projects and individual initiatives to activate communities by improving public and semi-public spaces. A question arises whether the money and effort is spent reasonably. Do people actually use the new facilities? Are they encouraged to affect the form and function of their surrounding? Does the public space change according to some passing fancies, or according to the changing needs? To juxtapose the development of technical condition of infrastructure and functions offered by the space between buildings with the expectations of users, the author repeatedly views the scene and conducts structured

  11. Evaluate Influence to Space Lighting Intensity in Main Control Room of RSG-GAS

    International Nuclear Information System (INIS)

    Teguh-Sulistyo; Yuyut-S-M; Yahya; Adin S

    2006-01-01

    Have been done by an activity evaluate factor depreciation influence to light source in Main Control Room (RKU). This Factor Depreciation is resulted from by defilement of effect of dirt, duration of light source utilized, way of installation, and others. Method used by perceives directly at light source, determining measurement dot in space RKU, measurement by using meter lux equipment and group storey; level depreciation of light source become light depreciation, and heavy. Than measurement result that lighting intensity in space RKU experience of decrease of equal to 1.5 %. After by stage; steps overcome the factor depreciation, result of measurement repeat obtained by decrease of equal to 0.87 %. Thereby the lighting intensity in space RKU becomes better. (author)

  12. Influence of Layup Sequence on the Surface Accuracy of Carbon Fiber Composite Space Mirrors

    Science.gov (United States)

    Yang, Zhiyong; Liu, Qingnian; Zhang, Boming; Xu, Liang; Tang, Zhanwen; Xie, Yongjie

    2018-04-01

    Layup sequence is directly related to stiffness and deformation resistance of the composite space mirror, and error caused by layup sequence can affect the surface precision of composite mirrors evidently. Variation of layup sequence with the same total thickness of composite space mirror changes surface form of the composite mirror, which is the focus of our study. In our research, the influence of varied quasi-isotropic stacking sequences and random angular deviation on the surface accuracy of composite space mirrors was investigated through finite element analyses (FEA). We established a simulation model for the studied concave mirror with 500 mm diameter, essential factors of layup sequences and random angular deviations on different plies were discussed. Five guiding findings were described in this study. Increasing total plies, optimizing stacking sequence and keeping consistency of ply alignment in ply placement are effective to improve surface accuracy of composite mirror.

  13. Soil evolution in spruce forest ecosystems: role and influence of humus studied by morphological approach

    Directory of Open Access Journals (Sweden)

    Chersich S

    2007-01-01

    Full Text Available In order to understand the role and the mutual influences of humus and soil in alpine spruce forest ecosystems we studied and classified 7 soil - humic profiles on the 4 main forestry dynamics: open canopy, regeneration, young stand, tree stage. We studied the role of humification process in the pedologic process involving soils and vegetations studing humic and soil horizons. Study sites are located at an altitude of 1740 m a.s.l near Pellizzano (TN, and facing to the North. The parent soil material is predominantly composed of morenic sediments, probably from Cevedale glacier lying on a substrate of tonalite from Presanella (Adamello Tertiary pluton. The soil temperature regime is frigid, while the moisture regime is udic. The characteristics observed in field were correlated with classical chemical and physical soil analyses (MIPAF 2000. In order to discriminate the dominant soil forming process, the soils were described and classified in each site according to the World Reference Base (FAO-ISRIC-ISSS 1998. Humus was described and classified using the morphological-genetic approach (Jabiol et al. 1995. The main humus forms are acid and they are for the greater part Dysmoder on PODZOLS. The main pedogenetic processes is the podzolization, locally there are also hydromorphic processes. We associate a definite humus form with a pedological process at a particular step of the forest evolution. We concluded thath the soil study for a correct pedological interpretation must take count of the characteristics of the humic epipedon.

  14. Influence of the cementitious paste composition on the E-modulus and heat of hydration evolutions

    International Nuclear Information System (INIS)

    Maia, Lino; Azenha, Miguel; Faria, Rui; Figueiras, Joaquim

    2011-01-01

    E-modulus and heat of hydration are features of cement-based materials that follow a rapid rate of change at early ages. This paper analyses the influence of the composition of cementitious pastes on these features by using two methods: (i) a novel technique for continuously monitoring the E-modulus of cement-based materials, based on evaluating the first resonant frequency of a composite beam containing the material under testing, and (ii) an isothermal calorimeter to determine the released heat of hydration. Seventeen mixes are tested, encompassing pastes with five w/c ratios, as well as different contents of limestone filler, fly ash, silica fume and metakaolin. The results permit the comparison of the E-modulus and heat of hydration sensitivities to mix composition changes, and to check possible relations between these features. This work also helps to establish the technique (i) as a non-destructive method for monitoring the E-modulus evolution in cement-based materials since casting.

  15. Influence of helical external driven current on nonlinear resistive tearing mode evolution and saturation in tokamaks

    Science.gov (United States)

    Zhang, W.; Wang, S.; Ma, Z. W.

    2017-06-01

    The influences of helical driven currents on nonlinear resistive tearing mode evolution and saturation are studied by using a three-dimensional toroidal resistive magnetohydrodynamic code (CLT). We carried out three types of helical driven currents: stationary, time-dependent amplitude, and thickness. It is found that the helical driven current is much more efficient than the Gaussian driven current used in our previous study [S. Wang et al., Phys. Plasmas 23(5), 052503 (2016)]. The stationary helical driven current cannot persistently control tearing mode instabilities. For the time-dependent helical driven current with f c d = 0.01 and δ c d < 0.04 , the island size can be reduced to its saturated level that is about one third of the initial island size. However, if the total driven current increases to about 7% of the total plasma current, tearing mode instabilities will rebound again due to the excitation of the triple tearing mode. For the helical driven current with time dependent strength and thickness, the reduction speed of the radial perturbation component of the magnetic field increases with an increase in the driven current and then saturates at a quite low level. The tearing mode is always controlled even for a large driven current.

  16. Influence of HMW tail chains on the structural evolution of HDPE induced by second melt penetration.

    Science.gov (United States)

    Zhu, Chun-Xia; Xia, Xiao-Chao; Huang, Yan-Hao; Xie, Dan-Dan; Chen, Rui; Yang, Ming-Bo

    2017-07-21

    It is widely accepted that the role of the high molecular weight (HMW) component is cooperative in shear-induced crystallization, owing to entanglements among long chains. However, this paper demonstrates that the HMW component has a novel effect on structural evolution during the process of multi-melt multi-injection molding (M 3 IM), organized as follows. First, the appropriate HDPE system with an incremental concentration of HMW tails was established. Second, the crystalline morphologies and orientation behaviors of the M 3 IM samples were characterized using a combination of scanning electron microscopy (SEM) and two-dimensional small angle X-ray scattering (2D-SAXS), and these suggested that the amount of shish-kebabs was not monotonically promoted with an increasing content of HMW tails but tended to reduce at a certain value. Third, in order to explain this phenomenon, the special temperature and shear profiles of M 3 IM were depicted subsequently, and finally the mechanism of hierarchical structure formation with the influence of various amounts of HMW tail chains was discussed, based on the classical rheological viewpoint.

  17. Influence of the interfacial peptide organization on the catalysis of hydrogen evolution.

    Science.gov (United States)

    Doneux, Th; Dorcák, V; Palecek, E

    2010-01-19

    The hydrogen evolution reaction is catalyzed by peptides and proteins adsorbed on electrode materials with high overpotentials for this reaction, such as mercury. The catalytic response characteristics are known to be very sensitive to the composition and structure of the investigated biomolecule, opening the way to the implementation of a label-free, reagentless electroanalytical method in protein analysis. Herein, it is shown using the model peptide Cys-Ala-Ala-Ala-Ala-Ala that the interfacial organization significantly influences the catalytic behavior. This peptide forms at the electrode two distinct films, depending on the concentration and accumulation time. The low-coverage film, composed of flat-lying molecules (area per molecule of approximately 250-290 A(2)), yields a well-defined catalytic peak at potentials around -1.75 V. The high-coverage film, made of upright-oriented peptides (area per molecule of approximately 43 A(2)), is catalytically more active and the peak is observed at potentials less negative by approximately 0.4 V. The higher activity, evidenced by constant-current chronopotentiometry and cyclic voltammetry, is attributed to an increase in the acid dissociation constant of the amino acid residues as a result of the low permittivity of the interfacial region, as inferred from impedance measurements. An analogy is made to the known differences in acidic-basic behaviors of solvent-exposed and hydrophobic domains of proteins.

  18. Remote Sensing of Clouds And Precipitation: Event-Based Characterization, Life Cycle Evolution, and Aerosol Influences

    Science.gov (United States)

    Esmaili, Rebekah Bradley

    Global climate models, numerical weather prediction, and flood models rely on accurate satellite precipitation products, which are the only datasets that are continuous in time and space across the globe. While there are more earth observing satellites than ever before, gaps in precipitation retrievals exist due to sensor and orbital limitations of low-earth (LEO) satellites, which are overcome by merging data from different sensors in satellite precipitation products (SPPs). Using cloud tracking at higher resolutions than the spatio-temporal scales of LEO satellites, this thesis examines how clouds typically form in the atmosphere, the rate that cloud size and temperature evolve over the life cycle, and the time of day that cloud development take place. This thesis found that cloud evolution was non-linear, which disagrees with the linear interpolation schemes used in SPPs. Longer lasting clouds tended to achieve their temperature and size maturity milestones at different times, while these stages often occurred simultaneously in shorter lasting clouds. Over the ocean, longer lasting clouds were found to occur more frequently at night, while shorter lasting clouds were more common during the daytime. This thesis also examines whether large-scale Saharan dust outbreaks can impact the trajectories and intensity of cloud clusters in the tropical Atlantic, which is predicted by modeling studies. The presented results show that proximity to Saharan dust outbreaks shifts Atlantic cloud development northward and intense storms becoming more common, whereas on days with low dust loading small-scale, warmer clouds are more common. A simplified view of cloud evolution in merged rainfall retrievals is a possible source of errors, which can propagate into higher level analysis. This thesis investigates the difference in the intensity, duration, and frequency of precipitation in IMERG, a next-generation satellite precipitation product with ground radar observations over the

  19. Space Weather Influence on the Earth wheat markets: past, present, and future.

    Science.gov (United States)

    Pustil'Nik, Lev

    We consider problem of a possible influence of unfavorable states of the space weather on agriculture market through chain of connections: "space weather"-"earth weather"-"agriculture crops"-"price reaction". We show that new manifestations of "space weather"-"earth weather" relations discovered in the last time allow to revise wide field of expected solar-terrestrial connections. In the previous works we proposed possible mechanisms of wheat market reaction in the form of price bursts on the specific unfavorable states of space weather. We show that implementation of considered "price reaction scenarios" is possible only for condition of simultaneous realization of several necessary conditions: high sensitivity of local earth weather in selected region to space weather; state of "high risk agriculture" in selected agriculture zone; high sensitivity of agricultural market to possible deficit of supply. Results of previous works (I, II) included application of this approach to wheat market in Medieval England and to modern USA durum market showed that real connection between wheat price bursts and space weather state is observed with high confidence level. The aim of present work is answer on the question, why wheat markets in one region are sensitive to space weather factor, while another regional wheat markets demonstrate absolute indifferent reaction on this factor. For this aim we consider distribution of sensitivity of wheat markets in Europe to space weather as function of localization in different climatic zones. We analyze giant database of 95 European wheat markets from 14 countries during about 600-year period (1260-1912). We show that observed sensitivity of wheat market to space weather effects controlled, first of all, by type of predominant climate in different zones of agriculture. Wheat markets in the North and part of Central Europe (England, Iceland, Holland) shows reliable sensitivity to space weather in minimum states of solar activity with low

  20. Pleiotropy constrains the evolution of protein but not regulatory sequences in a transcription regulatory network influencing complex social behaviours

    Directory of Open Access Journals (Sweden)

    Daria eMolodtsova

    2014-12-01

    Full Text Available It is increasingly apparent that genes and networks that influence complex behaviour are evolutionary conserved, which is paradoxical considering that behaviour is labile over evolutionary timescales. How does adaptive change in behaviour arise if behaviour is controlled by conserved, pleiotropic, and likely evolutionary constrained genes? Pleiotropy and connectedness are known to constrain the general rate of protein evolution, prompting some to suggest that the evolution of complex traits, including behaviour, is fuelled by regulatory sequence evolution. However, we seldom have data on the strength of selection on mutations in coding and regulatory sequences, and this hinders our ability to study how pleiotropy influences coding and regulatory sequence evolution. Here we use population genomics to estimate the strength of selection on coding and regulatory mutations for a transcriptional regulatory network that influences complex behaviour of honey bees. We found that replacement mutations in highly connected transcription factors and target genes experience significantly stronger negative selection relative to weakly connected transcription factors and targets. Adaptively evolving proteins were significantly more likely to reside at the periphery of the regulatory network, while proteins with signs of negative selection were near the core of the network. Interestingly, connectedness and network structure had minimal influence on the strength of selection on putative regulatory sequences for both transcription factors and their targets. Our study indicates that adaptive evolution of complex behaviour can arise because of positive selection on protein-coding mutations in peripheral genes, and on regulatory sequence mutations in both transcription factors and their targets throughout the network.

  1. Evolution of the Systems Engineering Education Development (SEED) Program at NASA Goddard Space Flight Center

    Science.gov (United States)

    Bagg, Thomas C., III; Brumfield, Mark D.; Jamison, Donald E.; Granata, Raymond L.; Casey, Carolyn A.; Heller, Stuart

    2003-01-01

    The Systems Engineering Education Development (SEED) Program at NASA Goddard Space Flight Center develops systems engineers from existing discipline engineers. The program has evolved significantly since the report to INCOSE in 2003. This paper describes the SEED Program as it is now, outlines the changes over the last year, discusses current status and results, and shows the value of human systems and leadership skills for practicing systems engineers.

  2. Evolution of fractality in space plasmas of interest to geomagnetic activity

    Science.gov (United States)

    Muñoz, Víctor; Domínguez, Macarena; Alejandro Valdivia, Juan; Good, Simon; Nigro, Giuseppina; Carbone, Vincenzo

    2018-03-01

    We studied the temporal evolution of fractality for geomagnetic activity, by calculating fractal dimensions from the Dst data and from a magnetohydrodynamic shell model for turbulent magnetized plasma, which may be a useful model to study geomagnetic activity under solar wind forcing. We show that the shell model is able to reproduce the relationship between the fractal dimension and the occurrence of dissipative events, but only in a certain region of viscosity and resistivity values. We also present preliminary results of the application of these ideas to the study of the magnetic field time series in the solar wind during magnetic clouds, which suggest that it is possible, by means of the fractal dimension, to characterize the complexity of the magnetic cloud structure.

  3. The influence of tactile cognitive maps on auditory space perception in sighted persons.

    Directory of Open Access Journals (Sweden)

    Alessia Tonelli

    2016-11-01

    Full Text Available We have recently shown that vision is important to improve spatial auditory cognition. In this study we investigate whether touch is as effective as vision to create a cognitive map of a soundscape. In particular we tested whether the creation of a mental representation of a room, obtained through tactile exploration of a 3D model, can influence the perception of a complex auditory task in sighted people. We tested two groups of blindfolded sighted people – one experimental and one control group – in an auditory space bisection task. In the first group the bisection task was performed three times: specifically, the participants explored with their hands the 3D tactile model of the room and were led along the perimeter of the room between the first and the second execution of the space bisection. Then, they were allowed to remove the blindfold for a few minutes and look at the room between the second and third execution of the space bisection. Instead, the control group repeated for two consecutive times the space bisection task without performing any environmental exploration in between. Considering the first execution as a baseline, we found an improvement in the precision after the tactile exploration of the 3D model. Interestingly, no additional gain was obtained when room observation followed the tactile exploration, suggesting that no additional gain was obtained by vision cues after spatial tactile cues were internalized. No improvement was found between the first and the second execution of the space bisection without environmental exploration in the control group, suggesting that the improvement was not due to task learning. Our results show that tactile information modulates the precision of an ongoing space auditory task as well as visual information. This suggests that cognitive maps elicited by touch may participate in cross-modal calibration and supra-modal representations of space that increase implicit knowledge about sound

  4. Lie symmetry analysis, explicit solutions and conservation laws for the space-time fractional nonlinear evolution equations

    Science.gov (United States)

    Inc, Mustafa; Yusuf, Abdullahi; Aliyu, Aliyu Isa; Baleanu, Dumitru

    2018-04-01

    This paper studies the symmetry analysis, explicit solutions, convergence analysis, and conservation laws (Cls) for two different space-time fractional nonlinear evolution equations with Riemann-Liouville (RL) derivative. The governing equations are reduced to nonlinear ordinary differential equation (ODE) of fractional order using their Lie point symmetries. In the reduced equations, the derivative is in Erdelyi-Kober (EK) sense, power series technique is applied to derive an explicit solutions for the reduced fractional ODEs. The convergence of the obtained power series solutions is also presented. Moreover, the new conservation theorem and the generalization of the Noether operators are developed to construct the nonlocal Cls for the equations . Some interesting figures for the obtained explicit solutions are presented.

  5. Black holes in a box: Toward the numerical evolution of black holes in AdS space-times

    International Nuclear Information System (INIS)

    Witek, Helvi; Nerozzi, Andrea; Cardoso, Vitor; Herdeiro, Carlos; Sperhake, Ulrich; Zilhao, Miguel

    2010-01-01

    The evolution of black holes in ''confining boxes'' is interesting for a number of reasons, particularly because it mimics the global structure of anti-de Sitter geometries. These are nonglobally hyperbolic space-times and the Cauchy problem may only be well defined if the initial data are supplemented by boundary conditions at the timelike conformal boundary. Here, we explore the active role that boundary conditions play in the evolution of a bulk black hole system, by imprisoning a black hole binary in a box with mirrorlike boundary conditions. We are able to follow the post-merger dynamics for up to two reflections off the boundary of the gravitational radiation produced in the merger. We estimate that about 15% of the radiation energy is absorbed by the black hole per interaction, whereas transfer of angular momentum from the radiation to the black hole is observed only in the first interaction. We discuss the possible role of superradiant scattering for this result. Unlike the studies with outgoing boundary conditions, both of the Newman-Penrose scalars Ψ 4 and Ψ 0 are nontrivial in our setup, and we show that the numerical data verifies the expected relations between them.

  6. Space-time evolution of a growth fold (Betic Cordillera, Spain). Evidences from 3D geometrical modelling

    Science.gov (United States)

    Martin-Rojas, Ivan; Alfaro, Pedro; Estévez, Antonio

    2014-05-01

    We present a study that encompasses several software tools (iGIS©, ArcGIS©, Autocad©, etc.) and data (geological mapping, high resolution digital topographic data, high resolution aerial photographs, etc.) to create a detailed 3D geometric model of an active fault propagation growth fold. This 3D model clearly shows structural features of the analysed fold, as well as growth relationships and sedimentary patterns. The results obtained permit us to discuss the kinematics and structural evolution of the fold and the fault in time and space. The study fault propagation fold is the Crevillente syncline. This fold represents the northern limit of the Bajo Segura Basin, an intermontane basin in the Eastern Betic Cordillera (SE Spain) developed from upper Miocene on. 3D features of the Crevillente syncline, including growth pattern, indicate that limb rotation and, consequently, fault activity was higher during Messinian than during Tortonian; consequently, fault activity was also higher. From Pliocene on our data point that limb rotation and fault activity steadies or probably decreases. This in time evolution of the Crevillente syncline is not the same all along the structure; actually the 3D geometric model indicates that observed lateral heterogeneity is related to along strike variation of fault displacement.

  7. Evolution equation for the B-meson distribution amplitude in the heavy-quark effective theory in coordinate space

    International Nuclear Information System (INIS)

    Kawamura, Hiroyuki; Tanaka, Kazuhiro

    2010-01-01

    The B-meson distribution amplitude (DA) is defined as the matrix element of a quark-antiquark bilocal light-cone operator in the heavy-quark effective theory, corresponding to a long-distance component in the factorization formula for exclusive B-meson decays. The evolution equation for the B-meson DA is governed by the cusp anomalous dimension as well as the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-type anomalous dimension, and these anomalous dimensions give the ''quasilocal'' kernel in the coordinate-space representation. We show that this evolution equation can be solved analytically in the coordinate space, accomplishing the relevant Sudakov resummation at the next-to-leading logarithmic accuracy. The quasilocal nature leads to a quite simple form of our solution which determines the B-meson DA with a quark-antiquark light-cone separation t in terms of the DA at a lower renormalization scale μ with smaller interquark separations zt (z≤1). This formula allows us to present rigorous calculation of the B-meson DA at the factorization scale ∼√(m b Λ QCD ) for t less than ∼1 GeV -1 , using the recently obtained operator product expansion of the DA as the input at μ∼1 GeV. We also derive the master formula, which reexpresses the integrals of the DA at μ∼√(m b Λ QCD ) for the factorization formula by the compact integrals of the DA at μ∼1 GeV.

  8. Evolution of International Space Station GN&C System Across ISS Assembly Stages

    Science.gov (United States)

    Lee, Roscoe; Frank, K. D. (Technical Monitor)

    1999-01-01

    The Guidance Navigation and Control (GN&C) system for the International Space Station is initially implemented by the Functional Cargo Block (FGB) which was built by the Khrunichev Space Center under direct contract to Boeing. This element (Stage 1A/R) was launched on 20 November 1998 and is currently operating on-orbit. The components and capabilities of the FGB Motion Control System (MCS) are described. The next ISS element, which has GN&C functionality will be the Service Module (SM) built by Rocket Space Corporation-Energia. This module is scheduled for launch (Stage 1R) in early 2000. Following activation of the SM GN&C system, the FGB MCS is deactivated and no longer used. The components and capabilities of the SM GN&C system are described. When a Progress vehicle is attached to the ISS it can be used for reboost operations, based on commands provided by the Mission Control Center-Moscow. When a data connection is implemented between the SM and the Progress, the SM can command the Progress thrusters for attitude control and reboosts. On Stage 5A, the U.S. GN&C system will become activated when the U.S. Laboratory is de loyed and installed (launch schedule is currently TBD). The U.S. GN&C system provides non-propulsive control capabilities to support micro-gravity operations and minimize the use of propellant for attitude control, and an independent capability for determining the ISS state vector, attitude, attitude rate. and time.. The components and capabilities of the U.S. GN&C system are described and the interactions between the U.S. and Russian Segment GN&C systems are also described.

  9. The influence of eruption season on the global aerosol evolution and radiative impact of tropical volcanic eruptions

    Directory of Open Access Journals (Sweden)

    M. Toohey

    2011-12-01

    Full Text Available Simulations of tropical volcanic eruptions using a general circulation model with coupled aerosol microphysics are used to assess the influence of season of eruption on the aerosol evolution and radiative impacts at the Earth's surface. This analysis is presented for eruptions with SO2 injection magnitudes of 17 and 700 Tg, the former consistent with estimates of the 1991 Mt. Pinatubo eruption, the later a near-"super eruption". For each eruption magnitude, simulations are performed with eruptions at 15° N, at four equally spaced times of year. Sensitivity to eruption season of aerosol optical depth (AOD, clear-sky and all-sky shortwave (SW radiative flux is quantified by first integrating each field for four years after the eruption, then calculating for each cumulative field the absolute or percent difference between the maximum and minimum response from the four eruption seasons. Eruption season has a significant influence on AOD and clear-sky SW radiative flux anomalies for both eruption magnitudes. The sensitivity to eruption season for both fields is generally weak in the tropics, but increases in the mid- and high latitudes, reaching maximum values of ~75 %. Global mean AOD and clear-sky SW anomalies show sensitivity to eruption season on the order of 15–20 %, which results from differences in aerosol effective radius for the different eruption seasons. Smallest aerosol size and largest cumulative impact result from a January eruption for Pinatubo-magnitude eruption, and from a July eruption for the near-super eruption. In contrast to AOD and clear-sky SW anomalies, all-sky SW anomalies are found to be insensitive to season of eruption for the Pinatubo-magnitude eruption experiment, due to the reflection of solar radiation by clouds in the mid- to high latitudes. However, differences in all-sky SW anomalies between eruptions in different seasons are significant for the larger eruption magnitude, and the ~15 % sensitivity to

  10. Influence of psychological variables in morbidly obese patients undergoing bariatric surgery after 24 months of evolution.

    Science.gov (United States)

    Rodríguez-Hurtado, José; Ferrer-Márquez, Manuel; Fontalba-Navas, Andrés; García-Torrecillas, Juan Manuel; Olvera-Porcel, M Carmen

    Bariatric surgery is considered a more effective means of achieving weight loss than non-surgical options in morbid obesity. Rates of failure or relapse range from 20 to 30%. The study aims to analyse the influence of psychological variables (self-esteem, social support, coping strategies and personality) in the maintenance of weight loss after bariatric surgery. A cohort study was conducted involving 64 patients undergoing bariatric surgery for 24 months. At the end of the follow-up period, patients were divided into 2sub-cohorts classified as successes or failures. Success or favorable development was considered when the value of percent excess weight loss was 50 or higher. No statistically significant differences were observed between the 2groups in any variable studied. All patients had high self-esteem (87,3 those who failed and 88,1 those who are successful) and social support (90,2 and 90,9). Patients who succeed presented higher scores for cognitive restructuring (57,1) and were more introverted (47,1), while those who failed scored more highly in desiderative thinking (65,7) and were more prone to aggression (50,7) and neuroticism (51,7). High self-esteem and social support does not guarantee successful treatment. The groups differed in how they coped with obesity but the data obtained do not justify the weight evolution. In the absence of psychopathology, personality trait variability between patients is insufficient to predict the results. Copyright © 2017 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

  11. [Ecological Footprint Evolution Characteristics and Its Influencing Factors in China from 2000 to 2010].

    Science.gov (United States)

    Huang, Bao-rong; Cui, Shu-hong; Li, Ying-ming

    2016-02-15

    According to global average land productivities in 2000, this study calculated ecological footprint (EF) in China from 2000 to 2010, and analyzed its dynamic characteristics and socio-economic driving forces. The results showed that the total EF in China increased from 1.769 to 3.259 billion global hectares (gha) from 2000 to 2010, and its annual growth rate was 6.30%. Carbon Footprint was the fastest growth type of EF. It increased from 0.742 to 1.805 billion gha, and its annual growth rate was 9.29%. The net increase of cropland Footprint was also large in comparison to other types of Footprint. It increased from 0.678 to 0.891 billion gha. Per capita EF in China increased from 1.40 to 2.43 gha in this period. Although it was still below the world average level, it was far beyond per capita ecological carrying capacity in China, which led to serious ecological deficit and severe ecological crisis in China. The fast growth of per capita EF was the main driving force for the growth of total EF in China during the study period. Further, the growth of per capita EF was positively influenced by the growth of per capita consumption of products and severs, which was driven by economic growth and urbanization. Meanwhile, a large amount of exports of resource-intensive products in international trade was also an important driving force for EF growth. According to the evolution route of per capita EF in developed countries, along with China moving from middle-income to high-income country, per capita EF will maintain rapid growth, and ecological deficit in China will further exacerbate.

  12. Evolution in the Southeastern USA: Factors Influencing Acceptance and Rejection in Pre-Service Science Teachers

    Science.gov (United States)

    Glaze, Amanda L.; Goldston, M. Jenice; Dantzler, John

    2015-01-01

    Evolution continues to be a controversial topic around the world but nowhere is this more apparent locally than in the Southeastern region of the USA. In this study, we explored acceptance and rejection of evolution among pre-service science teachers in a teaching college in the rural Southeast and sought to determine (1) what relationships exist…

  13. Robust space-time extraction of ventricular surface evolution using multiphase level sets

    Science.gov (United States)

    Drapaca, Corina S.; Cardenas, Valerie; Studholme, Colin

    2004-05-01

    This paper focuses on the problem of accurately extracting the CSF-tissue boundary, particularly around the ventricular surface, from serial structural MRI of the brain acquired in imaging studies of aging and dementia. This is a challenging problem because of the common occurrence of peri-ventricular lesions which locally alter the appearance of white matter. We examine a level set approach which evolves a four dimensional description of the ventricular surface over time. This has the advantage of allowing constraints on the contour in the temporal dimension, improving the consistency of the extracted object over time. We follow the approach proposed by Chan and Vese which is based on the Mumford and Shah model and implemented using the Osher and Sethian level set method. We have extended this to the 4 dimensional case to propagate a 4D contour toward the tissue boundaries through the evolution of a 5D implicit function. For convergence we use region-based information provided by the image rather than the gradient of the image. This is adapted to allow intensity contrast changes between time frames in the MRI sequence. Results on time sequences of 3D brain MR images are presented and discussed.

  14. Oceanic magmatic evolution during ocean opening under influence of mantle plume

    Science.gov (United States)

    Sushchevskaya, Nadezhda; Melanholina, Elena; Belyatsky, Boris; Krymsky, Robert; Migdisova, Natalya

    2015-04-01

    influence on the SEIR formation occurred 70-50 mln years ago, when the process of primary magma generation happened at high degrees of melting (up to 30%), which is not typical for spreading ridges of the Atlantic and Pacific Oceans. According to geochemical characteristics of the Kerguelen Plateau and SEIR magma sources close to each other, and have an enriched source of more typical for Kerguelen plume magmas and diluted by depleted substance for SEIR melts. Appearance of magmatism on the Antarctic margin about 56 thousand years ago, in the form of a stratovolcano Gaussberg indicates sublithospheric Kerguelen plume distribution in the south-west direction. The source of primary magmas (lamproite composition) is an ancient Gondwana lithosphere, has undergone repeated changes in the early stages of evolution during which it was significantly enriched in volatile and lithophile elements, and radiogenic Sr and Pb.

  15. A Hybrid Optimization Framework with POD-based Order Reduction and Design-Space Evolution Scheme

    Science.gov (United States)

    Ghoman, Satyajit S.

    The main objective of this research is to develop an innovative multi-fidelity multi-disciplinary design, analysis and optimization suite that integrates certain solution generation codes and newly developed innovative tools to improve the overall optimization process. The research performed herein is divided into two parts: (1) the development of an MDAO framework by integration of variable fidelity physics-based computational codes, and (2) enhancements to such a framework by incorporating innovative features extending its robustness. The first part of this dissertation describes the development of a conceptual Multi-Fidelity Multi-Strategy and Multi-Disciplinary Design Optimization Environment (M3 DOE), in context of aircraft wing optimization. M 3 DOE provides the user a capability to optimize configurations with a choice of (i) the level of fidelity desired, (ii) the use of a single-step or multi-step optimization strategy, and (iii) combination of a series of structural and aerodynamic analyses. The modularity of M3 DOE allows it to be a part of other inclusive optimization frameworks. The M 3 DOE is demonstrated within the context of shape and sizing optimization of the wing of a Generic Business Jet aircraft. Two different optimization objectives, viz. dry weight minimization, and cruise range maximization are studied by conducting one low-fidelity and two high-fidelity optimization runs to demonstrate the application scope of M3 DOE. The second part of this dissertation describes the development of an innovative hybrid optimization framework that extends the robustness of M 3 DOE by employing a proper orthogonal decomposition-based design-space order reduction scheme combined with the evolutionary algorithm technique. The POD method of extracting dominant modes from an ensemble of candidate configurations is used for the design-space order reduction. The snapshot of candidate population is updated iteratively using evolutionary algorithm technique of

  16. Origin of unbalanced reaction of vacancies and interstitials during irradiation with cascades and influence on microstructural evolution

    International Nuclear Information System (INIS)

    Kiritani, M.; Yoshiie, T.; Kojima, S.; Satoh, Y.

    1993-01-01

    Based upon the underlying premise that all the microstructure evolution during irradiation results from the asymetrical reaction between vacancies and interstitials, the origin of the asymetry is sought and categorized, and the mechanism of defect structure evolution for each source of asymetry is investigated. The role of neutral sinks and the influence of dislocations are examined for the cases of irradiation with and without cascade damage. Vacancy cluster formation directly from cascades is found to favor the generation of freely migrating interstitials. Stochastic fluctuations of the point defect reactions under the balanced condition of vacancy and interstitial is experimentally detected, and the important role of the fluctuations is found in the determination of the fate of small interstitial cluster embryos produced by cascade damage. The influence of the unbalanced point defect reaction starting from difference in spacial distribution between vacancies and interstitials formed by cascade collisions is discussed as one of the important origins of vacancy dominant reactions. (orig.)

  17. NASA's Evolution to K(sub a)- Band Space Communications for Near-Earth Spacecraft

    Science.gov (United States)

    McCarthy, Kevin P.; Stocklin, Frank J.; Geldzahler, Barry J.; Friedman, Daniel E.; Celeste, Peter B.

    2010-01-01

    Over the next several years, NASA plans to launch multiple earth-science missions which will send data from low-Earth orbits to ground stations at 1-3 Gbps, to achieve data throughputs of 5-40 terabits per day. These transmission rates exceed the capabilities of S-band and X-band frequency allocations used for science probe downlinks in the past. Accordingly, NASA is exploring enhancements to its space communication capabilities to provide the Agency's first Ka-band architecture solution for next generation missions in the near-earth regime. This paper describes the proposed Ka-band solution's drivers and concept, constraints and analyses which shaped that concept, and expansibility for future needs

  18. Characterizing the Evolution of Circumstellar Systems with the Hubble Space Telescope and the Gemini Planet Imager

    Science.gov (United States)

    Wolff, Schuyler; Schuyler G. Wolff

    2018-01-01

    The study of circumstellar disks at a variety of evolutionary stages is essential to understand the physical processes leading to planet formation. The recent development of high contrast instruments designed to directly image the structures surrounding nearby stars, such as the Gemini Planet Imager (GPI) and coronagraphic data from the Hubble Space Telescope (HST) have made detailed studies of circumstellar systems possible. In my thesis work I detail the observation and characterization of three systems. GPI polarization data for the transition disk, PDS 66 shows a double ring and gap structure with a temporally variable azimuthal asymmetry. This evolved morphology could indicate shadowing from some feature in the innermost regions of the disk, a gap-clearing planet, or a localized change in the dust properties of the disk. Millimeter continuum data of the DH Tau system places limits on the dust mass that is contributing to the strong accretion signature on the wide-separation planetary mass companion, DH Tau b. The lower than expected dust mass constrains the possible formation mechanism, with core accretion followed by dynamical scattering being the most likely. Finally, I present HST scattered light observations of the flared, edge-on protoplanetary disk ESO H$\\alpha$ 569. I combine these data with a spectral energy distribution to model the key structural parameters such as the geometry (disk outer radius, vertical scale height, radial flaring profile), total mass, and dust grain properties in the disk using the radiative transfer code MCFOST. In order to conduct this work, I developed a new tool set to optimize the fitting of disk parameters using the MCMC code \\texttt{emcee} to efficiently explore the high dimensional parameter space. This approach allows us to self-consistently and simultaneously fit a wide variety of observables in order to place constraints on the physical properties of a given disk, while also rigorously assessing the uncertainties in

  19. The development of test beds to support the definition and evolution of the Space Station Freedom power system

    Science.gov (United States)

    Soeder, James F.; Frye, Robert J.; Phillips, Rudy L.

    1991-01-01

    Since the beginning of the Space Station Freedom Program (SSFP), the NASA Lewis Research Center (LeRC) and the Rocketdyne Division of Rockwell International have had extensive efforts underway to develop testbeds to support the definition of the detailed electrical power system design. Because of the extensive redirections that have taken place in the Space Station Freedom Program in the past several years, the test bed effort was forced to accommodate a large number of changes. A short history of these program changes and their impact on the LeRC test beds is presented to understand how the current test bed configuration has evolved. The current test objectives and the development approach for the current DC test bed are discussed. A description of the test bed configuration, along with its power and controller hardware and its software components, is presented. Next, the uses of the test bed during the mature design and verification phase of SSFP are examined. Finally, the uses of the test bed in the operation and evolution of the SSF are addressed.

  20. A Long-Term Space Astrophysics Research Program: The Evolution of the Quasar Continuum

    Science.gov (United States)

    Elvis, M.; Oliversen, Ronald K. (Technical Monitor)

    2001-01-01

    Four papers have been written. One reports on the major study funded by this grant: a pan-chromatic study of the quasar continuum at redshift 3. Two others make use of the quasar continuum shapes to find the minimum total accretion luminosity of the Universe, and hence the efficiency and spin of supermassive black holes; the second shows that the reemission of absorbed quasar radiation alleviates a major problem with galaxy formation and the FIR background. The last paper recognizes the role quasars may play in the initial formation of dust in the early Universe. The major study of a sample of z=3 and its comparison with a sample of z=0.l quasars across the whole X-ray to radio spectrum was completed and accepted for publication in ApJ Supplements. This study comprises the thesis work of Olga Kuhn. The two samples are matched in evolved luminosity, and so should be sampling the same black hole population at different z, and in different accretion states. Despite this no strong differences were found between the samples, except in the 'small bump' region of the optical/UV. This region is dominated by FeII emission, and may indicate abundance evolution in quasars. The lack of overall spectral changes argues strongly against a single population of quasars fading over cosmic time, and for a multiple generation, or multiple outburst model for quasars. A study of the total luminosity absorbed from quasars and re-emitted in the infrared produced two results (reported in two papers): The minimum intrinsic luminosity/Gpc(3) from AGN compared with the measured mass density in supermassive black holes [Gpc(-3)] requires a conversion efficiency of accreted mass into luminosity of greater than 15%. Non-rotating black holes cannot exceed 5% efficiency, while rapidly rotating black holes can reach 47%. Hence our result requires that most supermassive black holes must be rapidly rotating. The second result comes from considering the contribution that the re-radiated quasar

  1. Predator attack rate evolution in space: the role of ecology mediated by complex emergent spatial structure and self-shading.

    Science.gov (United States)

    Messinger, Susanna M; Ostling, Annette

    2013-11-01

    Predation interactions are an important element of ecological communities. Population spatial structure has been shown to influence predator evolution, resulting in the evolution of a reduced predator attack rate; however, the evolutionary role of traits governing predator and prey ecology is unknown. The evolutionary effect of spatial structure on a predator's attack rate has primarily been explored assuming a fixed metapopulation spatial structure, and understood in terms of group selection. But endogenously generated, emergent spatial structure is common in nature. Furthermore, the evolutionary influence of ecological traits may be mediated through the spatial self-structuring process. Drawing from theory on pathogens, the evolutionary effect of emergent spatial structure can be understood in terms of self-shading, where a voracious predator limits its long-term invasion potential by reducing local prey availability. Here we formalize the effects of self-shading for predators using spatial moment equations. Then, through simulations, we show that in a spatial context self-shading leads to relationships between predator-prey ecology and the predator's attack rate that are not expected in a non-spatial context. Some relationships are analogous to relationships already shown for host-pathogen interactions, but others represent new trait dimensions. Finally, since understanding the effects of ecology using existing self-shading theory requires simplifications of the emergent spatial structure that do not apply well here, we also develop metrics describing the complex spatial structure of the predator and prey populations to help us explain the evolutionary effect of predator and prey ecology in the context of self-shading. The identification of these metrics may provide a step towards expansion of the predictive domain of self-shading theory to more complex spatial dynamics. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Space Weather Influence on the Earth Climate: Possible Manifestations in Wheat Markets Reaction

    Science.gov (United States)

    Pustilnik, Lev; Yom Din, Gregory; Zagnetko, Alexander

    We consider problem of a possible influence of unfavorable states of the space weather on agri-culture market through chain of connections: "space weather"-"earth weather"-"agriculture crops"-"price reaction". We show that new manifestations of "space weather"-"earth weather" relations discovered in the last time allow to revise wide field of expected solar-terrestrial con-nections. In the previous works we proposed possible mechanisms of wheat market reaction in the form of price bursts on the specific unfavorable states of space weather. We show that implementation of considered "price reaction scenarios" is possible only for condition of simul-taneous realization of several necessary conditions: high sensitivity of local earth weather in selected region to space weather; state of "high risk agriculture" in selected agriculture zone; high sensitivity of agricultural market to possible deficit of supply. Results of previous works included application of this approach to wheat market in Medieval England and to modern USA durum market showed that real connection between wheat price bursts and space weather state is observed with high confidence level. The aim of present work is answer on the ques-tion, why wheat markets in one region are sensitive to space weather factor, while another regional wheat markets demonstrate absolute indifferent reaction on this factor. For this aim we consider distribution of sensitivity of wheat markets in Europe to space weather as function of localization in different climatic zones. We analyze giant database of 95 European wheat markets from 14 countries during about 600-year period (1260-1912). We show that observed sensitivity of wheat market to space weather effects controlled, first of all, by type of predomi-nant climate in different zones of agriculture. Wheat markets in the North and part of Central Europe (England, Iceland, Holland) shows reliable sensitivity to space weather in minimum states of solar activity with low

  3. THE SPACE DENSITY EVOLUTION OF WET AND DRY MERGERS IN THE CANADA-FRANCE-HAWAII TELESCOPE LEGACY SURVEY

    International Nuclear Information System (INIS)

    Chou, Richard C. Y.; Abraham, Roberto G.; Bridge, Carrie R.

    2011-01-01

    We analyze 1298 merging galaxies with redshifts up to z = 0.7 from the Canada-France-Hawaii Telescope Legacy Survey, taken from the catalog presented in the work of Bridge et al. By analyzing the internal colors of these systems, we show that the so-called wet and dry mergers evolve in different senses, and quantify the space densities of these systems. The local space density of wet mergers is essentially identical to the local space density of dry mergers. The evolution in the total merger rate is modest out to z ∼ 0.7, although the wet and dry populations have different evolutionary trends. At higher redshifts, dry mergers make a smaller contribution to the total merging galaxy population, but this is offset by a roughly equivalent increase in the contribution from wet mergers. By comparing the mass density function of early-type galaxies to the corresponding mass density function for merging systems, we show that not all the major mergers with the highest masses (M stellar >10 11 M sun ) will end up with the most massive early-type galaxies, unless the merging timescale is dramatically longer than that usually assumed. On the other hand, the usually assumed merging timescale of ∼0.5-1 Gyr is quite consistent with the data if we suppose that only less massive early-type galaxies form via mergers. Since low-intermediate-mass ellipticals are 10-100 times more common than their most massive counterparts, the hierarchical explanation for the origin of early-type galaxies may be correct for the vast majority of early types, even if incorrect for the most massive ones.

  4. An analysis of factors influencing the teaching of biological evolution in Louisiana public secondary schools

    Science.gov (United States)

    Aguillard, Donald Wayne

    Louisiana public school biology teachers were surveyed to investigate their attitudes toward biological evolution. A mixed method investigation was employed using a questionnaire and open-ended interviews. Results obtained from 64 percent of the sample receiving the questionnaire indicate that although teachers endorse the study of evolution as important, instructional time allocated to evolution is disproportionate with its status as a unifying concept of science. Two variables, number of college courses specifically devoted to evolution and number of semester credit hours in biology, produced a significant correlation with emphasis placed on evolution. The data suggest that teachers' knowledge base emerged as the most significant factor in determining degree of classroom emphasis on evolution. The data suggest a need for substantive changes in the training of biology teachers. Thirty-five percent of teachers reported pursuing fewer than 20 semester credit hours in biology and 68 percent reported fewer than three college courses in which evolution was specifically discussed. Fifty percent reported a willingness to undergo additional training about evolution. In spite of the fact that evolution has been identified as a major conceptual theme across all of the sciences, there is strong evidence that Louisiana biology teachers de-emphasize evolutionary theory. Even when biology teachers allocate instructional time to evolutionary theory, many avoid discussion of human evolution. The research data show that only ten percent of teachers reported allocating more than sixty minutes of instructional time to human evolution. Louisiana biology teachers were found to hold extreme views on the subject of creationism as a component of the biology curriculum. Twenty-nine percent indicated that creationism should be taught in high school biology and 25--35 percent allocated instructional time to discussions of creationism. Contributing to the de-emphasis of evolutionary theory

  5. Evolution of systems concepts for a 100 kWe class space nuclear power system

    International Nuclear Information System (INIS)

    Katucki, R.; Josloff, A.; Kirpich, A.; Florio, F.

    1985-01-01

    Conceptual designs for the SP-100 space nuclear power system have been prepared that meet baseline, backup and growth program scenarios. Near-term advancement in technology was considered in the design of the baseline concept. An improved silicon-germanium thermoelectric technique is used to convert the heat from a fast-spectrum, liquid lithium cooled reactor. This system produces a net power of 100 kWe with a 10-year end of life, under the specific constraints of area and volume. Output of the backup concept is estimated to be 60 kWe for a 10-year end of life. This system differs from the naseline concept because currently available thermoelectric conversion is used from energy supplied by a liquid sodium cooled reactor. The growth concept uses Stirling engine conversion to produce 100 kWe within the constraints of mass and volume. The growth concept can be scaled up to produce a 1 MWe output that uses the same type reactor developed for the baseline concept. Assessments made for each of the program scenarios indicate the key development efforts needed to initiate detailed design and hardware program phases. Development plans were prepared for each scenario that detail the work elements and show the program activities leading to a state of flight readiness

  6. Evolution of systems concepts for a 100 kWe class Space Nuclear Power System

    Science.gov (United States)

    Katucki, R.; Josloff, A.; Kirpich, A.; Florio, F.

    1985-01-01

    Conceptual designs for the SP-100 Space Nuclear Power System have been prepared that meet baseline, backup and growth program scenarios. Near-term advancement in technology was considered in the design of the Baseline Concept. An improved silicon-germanium thermoelectric technique is used to convert the heat from a fast-spectrum, liquid lithium cooled reactor. This system produces a net power of 100 kWe with a 10-year end of life, under the specific constraints of area and volume. Output of the Backup Concept is estimated to be 60 kWe for a 10-year end of life. This system differs from the Baseline Concept because currently available thermoelectric conversion is used from energy supplied by a liquid sodium cooled reactor. The Growth Concept uses Stirling engine conversion to produce 100 kWe within the constraints of mass and volume. The Growth Concept can be scaled up to produce a 1 MWe output that uses the same type reactor developed for the Baseline Concept. Assessments made for each of the program scenarios indicate the key development efforts needed to initiate detailed design and hardware program phases. Development plans were prepared for each scenario that detail the work elements and show the program activities leading to a state of flight readiness.

  7. Microfracture spacing distributions and the evolution of fracture patterns in sandstones

    Science.gov (United States)

    Hooker, J. N.; Laubach, S. E.; Marrett, R.

    2018-03-01

    Natural fracture patterns in sandstone were sampled using scanning electron microscope-based cathodoluminescence (SEM-CL) imaging. All fractures are opening-mode and are fully or partially sealed by quartz cement. Most sampled fractures are too small to be height-restricted by sedimentary layers. At very low strains ( 100) datasets show spacings that are best fit by log-normal size distributions, compared to exponential, power law, or normal distributions. The clustering of fractures suggests that the locations of natural factures are not determined by a random process. To investigate natural fracture localization, we reconstructed the opening history of a cluster of fractures within the Huizachal Group in northeastern Mexico, using fluid inclusions from synkinematic cements and thermal-history constraints. The largest fracture, which is the only fracture in the cluster visible to the naked eye, among 101 present, opened relatively late in the sequence. This result suggests that the growth of sets of fractures is a self-organized process, in which small, initially isolated fractures grow and progressively interact, with preferential growth of a subset of fractures developing at the expense of growth of the rest. Size-dependent sealing of fractures within sets suggests that synkinematic cementation may contribute to fracture clustering.

  8. Influence of metal elements on the evolution of CO and CH4 during ...

    African Journals Online (AJOL)

    ONOS

    2010-01-18

    Jan 18, 2010 ... State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Shaanxi 710049, People's ... of sodium and aluminum on the evolution of gas species ..... as fuel and its thermochemical behaviour.

  9. The influence of global benchmark oil prices on the regional oil spot market in multi-period evolution

    International Nuclear Information System (INIS)

    Jiang, Meihui; An, Haizhong; Jia, Xiaoliang; Sun, Xiaoqi

    2017-01-01

    Crude benchmark oil prices play a crucial role in energy policy and investment management. Previous research confined itself to studying the static, uncertain, short- or long-term relationship between global benchmark oil prices, ignoring the time-varying, quantitative, dynamic nature of the relationship during various stages of oil price volatility. This paper proposes a novel approach combining grey relation analysis, optimization wavelet analysis, and Bayesian network modeling to explore the multi-period evolution of the dynamic relationship between global benchmark oil prices and regional oil spot price. We analyze the evolution of the most significant decision-making risk periods, as well as the combined strategy-making reference oil prices and the corresponding periods during various stages of volatility. Furthermore, we determine that the network evolution of the quantitative lead/lag relationship between different influences of global benchmark oil prices shows a multi-period evolution phenomenon. For policy makers and market investors, our combined model can provide decision-making periods with the lowest expected risk and decision-making target reference oil prices and corresponding weights for strategy adjustment and market arbitrage. This study provides further information regarding period weights of target reference oil prices, facilitating efforts to perform multi-agent energy policy and intertemporal market arbitrage. - Highlights: • Multi-period evolution of the influence of different oil prices is discovered. • We combined grey relation analysis, optimization wavelet and Bayesian network. • The intensity of volatility, synchronization, and lead/lag effects are analyzed. • The target reference oil prices and corresponding period weights are determined.

  10. Evolution of International Space Station Program Safety Review Processes and Tools

    Science.gov (United States)

    Ratterman, Christian D.; Green, Collin; Guibert, Matt R.; McCracken, Kristle I.; Sang, Anthony C.; Sharpe, Matthew D.; Tollinger, Irene V.

    2013-01-01

    The International Space Station Program at NASA is constantly seeking to improve the processes and systems that support safe space operations. To that end, the ISS Program decided to upgrade their Safety and Hazard data systems with 3 goals: make safety and hazard data more accessible; better support the interconnection of different types of safety data; and increase the efficiency (and compliance) of safety-related processes. These goals are accomplished by moving data into a web-based structured data system that includes strong process support and supports integration with other information systems. Along with the data systems, ISS is evolving its submission requirements and safety process requirements to support the improved model. In contrast to existing operations (where paper processes and electronic file repositories are used for safety data management) the web-based solution provides the program with dramatically faster access to records, the ability to search for and reference specific data within records, reduced workload for hazard updates and approval, and process support including digital signatures and controlled record workflow. In addition, integration with other key data systems provides assistance with assessments of flight readiness, more efficient review and approval of operational controls and better tracking of international safety certifications. This approach will also provide new opportunities to streamline the sharing of data with ISS international partners while maintaining compliance with applicable laws and respecting restrictions on proprietary data. One goal of this paper is to outline the approach taken by the ISS Progrm to determine requirements for the new system and to devise a practical and efficient implementation strategy. From conception through implementation, ISS and NASA partners utilized a user-centered software development approach focused on user research and iterative design methods. The user-centered approach used on

  11. Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

    Directory of Open Access Journals (Sweden)

    B. Hubinger

    2011-12-01

    Full Text Available Karst aquifers evolve where the dissolution of soluble rocks causes the enlargement of discrete pathways along fractures or bedding planes, thus creating highly conductive solution conduits. To identify general interrelations between hydrogeological conditions and the properties of the evolving conduit systems the aperture-size frequency distributions resulting from generic models of conduit evolution are analysed. For this purpose, a process-based numerical model coupling flow and rock dissolution is employed. Initial protoconduits are represented by tubes with log-normally distributed aperture sizes with a mean μ0 = 0.5 mm for the logarithm of the diameters. Apertures are spatially uncorrelated and widen up to the metre range due to dissolution by chemically aggressive waters. Several examples of conduit development are examined focussing on influences of the initial heterogeneity and the available amount of recharge. If the available recharge is sufficiently high the evolving conduits compete for flow and those with large apertures and high hydraulic gradients attract more and more water. As a consequence, the positive feedback between increasing flow and dissolution causes the breakthrough of a conduit pathway connecting the recharge and discharge sides of the modelling domain. Under these competitive flow conditions dynamically stable bimodal aperture distributions are found to evolve, i.e. a certain percentage of tubes continues to be enlarged while the remaining tubes stay small-sized. The percentage of strongly widened tubes is found to be independent of the breakthrough time and decreases with increasing heterogeneity of the initial apertures and decreasing amount of available water. If the competition for flow is suppressed because the availability of water is strongly limited breakthrough of a conduit pathway is inhibited and the conduit pathways widen very slowly. The resulting aperture distributions are found to be

  12. The Evolution of Friction Stir Welding Theory at Marshall Space Flight Center

    Science.gov (United States)

    Nunes, Arthur C.

    2012-01-01

    From 1995 to the present the friction stir welding (FSW) process has been under study at Marshall Space Flight Center (MSFC). This is an account of the progressive emergence of a set of conceptual tools beginning with the discovery of the shear surface, wiping metal transfer, and the invention of a kinematic model and making possible a treatment of both metallurgical structure formation and process dynamics in friction stir welding from a unified point of view. It is generally observed that the bulk of the deformation of weld metal around the FSW pin takes place in a very narrow, almost discontinuous zone with high deformation rates characteristic of metal cutting. By 1999 it was realized that this zone could be treated as a shear surface like that in simple metal cutting models. At the shear surface the seam is drawn out and compressed and pressure and flow conditions determine whether or not a sound weld is produced. The discovery of the shear surface was followed by the synthesis of a simple 3- flow kinematic model of the FSW process. Relative to the tool the flow components are: (1) an approaching translational flow at weld speed V, (2) a rotating cylindrical plug flow with the angular velocity of the tool , and (3) a relatively slow ring vortex flow (like a smoke ring) encircling the tool and driven by shoulder scrolls and pin threads. The rotating plug flow picks up an element of weld metal, rotates it around with the tool, and deposits it behind the tool ( wiping metal transfer ); it forms plan section loops in tracers cut through by the tool. Radially inward flow from the ring vortex component retains metal longer in the rotating plug and outward flow expels metal earlier; this interaction forms the looping weld seam trace and the tongue and groove bimetallic weld contour. The radial components of the translational and ring vortex flows introduce parent metal intrusions into the small grained nugget material close to the tool shoulder; if this feature is

  13. Factors influencing efficiency of sliding mechanics to close extraction space: a systematic review.

    Science.gov (United States)

    Barlow, M; Kula, K

    2008-05-01

    To review recent literature to determine strength of clinical evidence concerning the influence of various factors on the efficiency (rate of tooth movement) of closing extraction spaces using sliding mechanics. A comprehensive systematic review on prospective clinical trials. An electronic search (1966-2006) of several databases limiting the searches to English and using several keywords was performed. Also a hand search of five key journals specifically searching for prospective clinical trials relevant to orthodontic space closure using sliding mechanics was completed. Outcome Measure - Rate of tooth movement. Ten prospective clinical trials comparing rates of closure under different variables and focusing only on sliding mechanics were selected for review. Of these ten trials on rate of closure, two compared arch wire variables, seven compared material variables used to apply force, and one examined bracket variables. Other articles which were not prospective clinical trials on sliding mechanics, but containing relevant information were examined and included as background information. CONCLUSION - The results of clinical research support laboratory results that nickel-titanium coil springs produce a more consistent force and a faster rate of closure when compared with active ligatures as a method of force delivery to close extraction space along a continuous arch wire; however, elastomeric chain produces similar rates of closure when compared with nickel-titanium springs. Clinical and laboratory research suggest little advantage of 200 g nickel-titanium springs over 150 g springs. More clinical research is needed in this area.

  14. Evolution of mechanical properties of boron/manganese 22MnB5 steel under magnetic pulse influences

    International Nuclear Information System (INIS)

    Falaleev, A P; Meshkov, V V; Vetrogon, A A; Shymchenko, A V

    2016-01-01

    The boron/manganese 22MnB5 steel can be noted as the widely used material for creation of details, which must withstand high amount of load and impact influences. The complexity and high labor input of restoration of boron steel parts leads to growing interest in the new forming technologies such as magnetic pulse forming. There is the investigation of the evolution of mechanical properties of 22MnB5 steel during the restoration by means of magnetic pulse influence and induction heating. The heating of 22MnB5 blanks to the temperature above 900 0 C was examined. The forming processes at various temperatures (800, 900 and 950 0 C) were performed during the experiments. The test measurements allowed to obtain the relationships between the strain and the operation parameters such as induced current, pulse discharge time and the operation temperature. Based on these results the assumption about usage of these parameters for control of deformation process was made. Taking into account the load distribution and the plasticity evolution during the heating process, the computer simulation was performed in order to obtain more clear strain distribution through the processed area. The measurement of hardness and the comparison with the properties evolution during hot stamping processes confirmed the obtained results. (paper)

  15. Evolution of students’ friendship networks: Examining the influence of group size

    Directory of Open Access Journals (Sweden)

    Valentina Sokolovska

    2017-01-01

    Full Text Available  The main aim of this study was to examine the effect of the network size on formation and evolution of students’ friendship relations. Data was collected from two groups of sociology freshmen: a group from the University of Belgrade, which represents a larger group, and a group from the University of Novi Sad, which represents a smaller group. The data was collected in three periods of one academic year. We analyzed the structural features of students’ networks and constructed a stochastic model of network evolution in order to explore how friendships form and change during one year. The results showed that structural features of the larger and the smaller group differ in each stage of friendship formation. At the beginning of group forming, small world structure was noticeable in the larger group, although full small world structure was not confirmed in both groups. Furthermore, transitivity of triads had effect on the evolution of the larger network, while balance or structural equivalence had effect on the evolution of the smaller network. Results of the structural analysis are in line with findings of the network evolution model and together they provide an insight into how friendship evolves in groups of different sizes.

  16. Absolute determination of radiation bursts and of proportional counters space charge effect through the influence method

    International Nuclear Information System (INIS)

    Rios, I.J.; Mayer, R.E.

    2016-01-01

    When proportional counters are employed in charge integration mode to determine the magnitude of a radiation pulse, so intense that individual detection events take place in a time too short to produce individual output pulses, mostly in pulsed neutron sources, the strong build-up of positive space charge reduces the electric multiplication factor of the proportional detector. Under such conditions the ensuing measurement underestimates the amount of radiation that interacted with the detector. If the geometric characteristics, the filling gas pressure and the voltage applied to that detector are known, it becomes possible to apply an analytical correction method to the measurement. In this article we present a method that allows to determine the absolute value of the detected radiation burst without the need to know the characteristics of the employed detectors. It is necessary to employ more than one detector, taking advantage of the Influence Method. The “Influence Method” is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency and without the need to register coincidences of any kind. This method exploits the influence of the presence of one detector in the count rate of another detector, when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency (Rios and Mayer, 2015 [1,2]). Its practical implementation in the measurement of a moderated neutron flux arising from an isotopic neutron source was exemplified in (Rios and Mayer, 2016 [3]) and the extension for multiple detectors in (Rios and Mayer 2016 [4]). - Highlights: • Absolute determination of radiation burst. • Proportional counters space charge effect. • Radiation measurements on pulsed devices.

  17. Hybrid models for the simulation of microstructural evolution influenced by coupled, multiple physical processes

    Energy Technology Data Exchange (ETDEWEB)

    Tikare, Veena [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hernandez-Rivera, Efrain [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Madison, Jonathan D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Holm, Elizabeth Ann [Carnegie Mellon Univ., Pittsburgh, PA (United States); Patterson, Burton R. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Homer, Eric R. [Brigham Young Univ., Provo, UT (United States). Dept. of Mechanical Engineering

    2013-09-01

    Most materials microstructural evolution processes progress with multiple processes occurring simultaneously. In this work, we have concentrated on the processes that are active in nuclear materials, in particular, nuclear fuels. These processes are coarsening, nucleation, differential diffusion, phase transformation, radiation-induced defect formation and swelling, often with temperature gradients present. All these couple and contribute to evolution that is unique to nuclear fuels and materials. Hybrid model that combines elements from the Potts Monte Carlo, phase-field models and others have been developed to address these multiple physical processes. These models are described and applied to several processes in this report. An important feature of the models developed are that they are coded as applications within SPPARKS, a Sandiadeveloped framework for simulation at the mesoscale of microstructural evolution processes by kinetic Monte Carlo methods. This makes these codes readily accessible and adaptable for future applications.

  18. Space use of wintering waterbirds in India: Influence of trophic ecology on home-range size

    Science.gov (United States)

    Namgail, Tsewang; Takekawa, John Y.; Balachandran, Sivananinthaperumal; Sathiyaselvam, Ponnusamy; Mundkur, Taej; Newman, Scott H.

    2014-01-01

    Relationship between species' home range and their other biological traits remains poorly understood, especially in migratory birds due to the difficulty associated with tracking them. Advances in satellite telemetry and remote sensing techniques have proved instrumental in overcoming such challenges. We studied the space use of migratory ducks through satellite telemetry with an objective of understanding the influence of body mass and feeding habits on their home-range sizes. We marked 26 individuals, representing five species of migratory ducks, with satellite transmitters during two consecutive winters in three Indian states. We used kernel methods to estimate home ranges and core use areas of these waterfowl, and assessed the influence of body mass and feeding habits on home-range size. Feeding habits influenced the home-range size of the migratory ducks. Carnivorous ducks had the largest home ranges, herbivorous ducks the smallest, while omnivorous species had intermediate home-ranges. Body mass did not explain variation in home-range size. To our knowledge, this is the first study of its kind on migratory ducks, and it has important implications for their conservation and management.

  19. Model of evolution of radioactive waste repositories and their influence on the resource-ecological safety of an adjoining territories

    International Nuclear Information System (INIS)

    Angelova, R.; Sandul, G.A.; Sen'ko, T.Ya.

    2002-01-01

    In this paper it is considered the mathematical model of evolution of radioactive waste (RAW) repositories and their influence on the resource-ecological safety (RES) and sustainable development of an adjoining territories. Heart of considered model consists of that RAW repository is considered as a system with two processes proceeding in parallel: deterioration of repository buildings, equipment etc. enlarging resource-ecological danger (RED) on account of probability increase (risk increase) of emergency conditions; natural decay of RAW being in repository that lead to RED decrease. Considered model allows to learn RAW repositories evolution in given time interval and to analyze their behavior at its different stages depending on state of repositories, e.g., their modernization or other events as well as to define periods of RAW repositories peak danger for environment

  20. Multi-objective trajectory optimization of Space Manoeuvre Vehicle using adaptive differential evolution and modified game theory

    Science.gov (United States)

    Chai, Runqi; Savvaris, Al; Tsourdos, Antonios; Chai, Senchun

    2017-07-01

    Highly constrained trajectory optimization for Space Manoeuvre Vehicles (SMV) is a challenging problem. In practice, this problem becomes more difficult when multiple mission requirements are taken into account. Because of the nonlinearity in the dynamic model and even the objectives, it is usually hard for designers to generate a compromised trajectory without violating strict path and box constraints. In this paper, a new multi-objective SMV optimal control model is formulated and parameterized using combined shooting-collocation technique. A modified game theory approach, coupled with an adaptive differential evolution algorithm, is designed in order to generate the pareto front of the multi-objective trajectory optimization problem. In addition, to improve the quality of obtained solutions, a control logic is embedded in the framework of the proposed approach. Several existing multi-objective evolutionary algorithms are studied and compared with the proposed method. Simulation results indicate that without driving the solution out of the feasible region, the proposed method can perform better in terms of convergence ability and convergence speed than its counterparts. Moreover, the quality of the pareto set generated using the proposed method is higher than other multi-objective evolutionary algorithms, which means the newly proposed algorithm is more attractive for solving multi-criteria SMV trajectory planning problem.

  1. Influence of vineyard altitude on Glera grape ripening (Vitis vinifera L.): effects on aroma evolution and wine sensory profile.

    Science.gov (United States)

    Alessandrini, Massimiliano; Gaiotti, Federica; Belfiore, Nicola; Matarese, Fabiola; D'Onofrio, Claudio; Tomasi, Diego

    2017-07-01

    Environmental factors have been acknowledged to greatly influence grape and wine aromas. Among them, the effect of altitude on grape aroma compounds has scarcely been debated in literature available to date. In the present study, we investigated the influence of altitude on grape composition and aroma evolution during ripening of Vitis vinifera L. cultivar Glera grown in Conegliano-Valdobbiadene DOCG area (Italy). The site at highest altitude (380 m above sea level) was warmer than the lowest site (200 m above sea level) and, even with differences in temperature in the range 1.5-2 °C, the impact of the cultivation site on grape ripening and aroma accumulation and preservation was significant. The lowest site demonstrated slower grape ripening, and grapes at harvest accumulated lower amounts of all of the main classes of aroma compounds typical of the Glera variety. Wines produced from the highest site were preferred in tasting trials for their more patent floral notes and elegance. Altitude strongly influences grape ripening evolution and flavour accumulation in the Glera grape, and this result accounts for the different styles in the sparkling wines subsequently produced. Moreover, the present study shows that aroma compound biosynthesis, particularly that of benzenoides, starts before véraison in Glera. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  2. Influence of shear and deviatoric stress on the evolution of permeability in fractured rock

    NARCIS (Netherlands)

    Faoro, Igor; Niemeijer, André; Marone, Chris; Elsworth, Derek

    The evolution of permeability in fractured rock as a function of effective normal stress, shear displacement, and damage remains a complex issue. In this contribution, we report on experiments in which rock surfaces were subject to direct shear under controlled pore pressure and true triaxial stress

  3. The Possible Influence of Curriculum Statements and Textbooks on Misconceptions: The Case of Evolution

    Science.gov (United States)

    Sanders, Martie; Makotsa, Dennis

    2016-01-01

    Curriculum statements and textbooks are considered to be vital support tools for teachers, particularly during times of curriculum innovation. A recent change in South Africa was the controversial inclusion of evolution in the school curriculum, raising serious concerns amongst biology teachers regarding the adequacy of their content and…

  4. SYNTHETIC AGB EVOLUTION .3. THE INFLUENCE OF DIFFERENT MASS-LOSS LAWS

    NARCIS (Netherlands)

    GROENEWEGEN, MAT; DEJONG, T

    In Paper I of this series we presented a model to calculate in a synthetic way the evolution of thermal-pulsing AGB stars. The model was applied to the LMC and values were derived for the minimum core mass for third dredge-up and the dredge-up efficiency. In Paper I mass loss on the AGB was

  5. Measurement of the influences relating to anthropization on the temporal evolution of the gravitational risks and the vulnerability.

    Science.gov (United States)

    Lebourg, T.; Llop, R.; Provitolo, D.; Allignol, F.; Zerathe, S.

    2009-04-01

    The objective of this paper is to show the impact of the instrumentation on an urban area on the principle of prevention of the landslides risk and thus to contribute to decrease the vulnerability for an urban long-term future development. We show that the analyze by instrumentation of triggered factors which characterize the risk (by the quantification of the evolution in time of the mechanical properties versus weathered processes) suggest that it exists a relation between "susceptibility of landslides" and urban development The evolution of the stakes during time is at the same time, factor of evolution of the susceptibility and triggered factor of the vulnerability evolution of urban areas. The scientific goal relates to the urban systems vulnerability and resilience modelling versus landslides processes for the assistance to the risks prevention. Indeed, the installation of an effective risks prevention policy is based on a good evaluation of the intensity, the period of return of the phenomena and their zone of expansion, but also on an identification of the sectors exposed to the risks, their vulnerability and their resilience. The strategy of prevention of the risks generally relates to the construction of fortifications to protect the society but it can also be founded on the resilience concept. This other approach is not opposed to the risk, but proposes to reduce the impacts. The anthroposysteme concept of makes it possible to take into accounts the determining role played by the human society in the space system evolution; natural and social systems associated on a given territory. The study of a space system passes then by the identification of components of the physical world (natural) and the living world (social), these two components forming integral part of the Society. To be concluded, this paper and study applies to the Mediterranean coastline anthroposystemes (northern bank) where urban growth, saturation of the littorals, constructions in

  6. The SPACE 1.0 model: a Landlab component for 2-D calculation of sediment transport, bedrock erosion, and landscape evolution

    Science.gov (United States)

    Shobe, Charles M.; Tucker, Gregory E.; Barnhart, Katherine R.

    2017-12-01

    Models of landscape evolution by river erosion are often either transport-limited (sediment is always available but may or may not be transportable) or detachment-limited (sediment must be detached from the bed but is then always transportable). While several models incorporate elements of, or transition between, transport-limited and detachment-limited behavior, most require that either sediment or bedrock, but not both, are eroded at any given time. Modeling landscape evolution over large spatial and temporal scales requires a model that can (1) transition freely between transport-limited and detachment-limited behavior, (2) simultaneously treat sediment transport and bedrock erosion, and (3) run in 2-D over large grids and be coupled with other surface process models. We present SPACE (stream power with alluvium conservation and entrainment) 1.0, a new model for simultaneous evolution of an alluvium layer and a bedrock bed based on conservation of sediment mass both on the bed and in the water column. The model treats sediment transport and bedrock erosion simultaneously, embracing the reality that many rivers (even those commonly defined as bedrock rivers) flow over a partially alluviated bed. SPACE improves on previous models of bedrock-alluvial rivers by explicitly calculating sediment erosion and deposition rather than relying on a flux-divergence (Exner) approach. The SPACE model is a component of the Landlab modeling toolkit, a Python-language library used to create models of Earth surface processes. Landlab allows efficient coupling between the SPACE model and components simulating basin hydrology, hillslope evolution, weathering, lithospheric flexure, and other surface processes. Here, we first derive the governing equations of the SPACE model from existing sediment transport and bedrock erosion formulations and explore the behavior of local analytical solutions for sediment flux and alluvium thickness. We derive steady-state analytical solutions for

  7. Influence of Clay Platelet Spacing on Oxygen Permeability of Thin Film Assemblies

    Science.gov (United States)

    Priolo, Morgan; Gamboa, Daniel; Grunlan, Jaime

    2010-03-01

    Thin films of anionic natural montmorrilonite clay and various polyelectrolytes have been produced by alternately dipping a plastic substrate into dilute aqueous mixtures containing each ingredient in an effort to show the influence of clay platelet spacing on thin film permeability. After polymer-clay layers have been sequentially deposited, the resulting transparent films exhibit a brick wall nanostructure comprised of completely exfoliated clay bricks in polymeric mortar. This brick wall forms an extremely tortuous path for a molecule to traverse, creating channels perpendicular to the concentration gradient that increase the molecule's diffusion length and delay its transmission. To a first approximation, greater clay spacing (i.e., reduced clay concentration) produces greater oxygen barrier. Oxygen transmission rates below 0.005 cm^3/m^2.day have been achieved for films with only eight clay layers (total thickness of only 200 nm). With optical transparencies greater than 86% and the ability to be microwaved, these thin film composites are good candidates for flexible electronics packaging and foil replacement for food.

  8. KOBRA 3 - a code for the calculation of space-charge-influenced trajectories in 3-dimensions

    International Nuclear Information System (INIS)

    Spaedtke, P.; Wipf, S.

    1989-06-01

    KOBRA3 is a three-dimensional multi-purpose program, written in standard FORTRAN77. The main purpose of the program is to calculate the trajectories of charged particles through a static electro-magnetic field in three dimensions. If space charge is not negligible its influence is taken into account by an iterative process. The Laplace equation is solved for the scalar potential. During the ray tracing, in which the equations of motion for charged particles are solved, the space charge term in the Poisson equation is distributed onto the mesh. By repeating this procedure the steady-state Vlasov equation is solved: ∇ 2 φ+∫∫∫f p dxdydz = 0, where φ is the electro-static potential and f p (r vector, v vector) describes the distribution of the charged particles in space. KOBRA3 can handle finite plasma boundaries, which are found by the program automatically. Special features are included within the program to investigate the beam quality (emittance, transverse energy), and to display the geometry, the trajectories and the potential and magnetic fields graphically. The modular structure of the program enables the user to create his (her) own diagnostic programs or interfaces to the main program. This report is intended to facilitate the use of KOBRA3 by describing the theory, structure and numerical methods used. At GSI (Gesellschaft fuer Schwerionenforschung) the program runs on an IBM 3090-40E. The program has been installed on other machines e.g. CRAY XM-P, CRAY II, VAX 8600, IBM 3090-200, IBM 3033, ATARI ST, IBM-AT. (orig./HSI)

  9. Evolution Dynamics of Relief and Sediment Structures During the Initial Phase of Ecosystem Evolution Within an Experimentally Constructed Catchment Landscape and Their Influence on the Shallow Subsurface

    Science.gov (United States)

    Huerkamp, K.; Voelkel, J.; Leopold, M.; Roeder, J.; Winkelbauer, J.

    2008-12-01

    The studies are integrated in a project of the Collaborative Research Center of the German Research Foundation (DFG SFB-TRR 38) 'Structures and processes of the initial ecosystem development phase in an artificial water catchment'. The experimental catchment 'Hühnerwasser' is built up by mechanically deposited sediments reconstructing an initially emerged landscape. In order to monitor its geomorphological as well as ecofunctional evolution with time it is essential to incorporate comprehensive geophysical applications dealing with geomorphology and sedimentology of both surface as well as shallow subsurface. Digital terrain modelling on meso- to microscale is employed to reflect and analyze superficial processes and evolution trends as well as their influence on the abiotic and biotic structures and processes of the succeeding ecosystem. Especially in the case of the portrayal and analysis of subsurface characteristics, strategy needs to adapt to the special requirements of the SFB-project as the catchment system should only underlie 'natural' conditions and therefore not be altered by any implementations in the course of field investigation. Consequently, intrusive methods such as drillings or profiles are to be omitted. Methods of geophysical prospection hence constitute an indispensable tool in investigation of subsurface composition. Ground penetrating radar (GPR) and electric resistivity tomography (ERT) are applied with adequate resolution to detect the primary deposition structures within the technogenically bedded sediment. By means of this evaluation subsurface structures can be interpreted with regards to their relevance in controlling soil water movement, slope hydrology, redox interactions, root distribution etc. Furthermore, alterations of these primary structures resulting from bio- and pedoturbation processes can be monitored.

  10. The influence of anxiety and personality factors on comfort and reachability space a correlational study

    NARCIS (Netherlands)

    Iachini, Tina; Ruggiero, Gennaro; Ruotolo, Francesco; Schiano di Cola, Armando; Senese, Vincenzo Paolo

    Although the effects of several personality factors on interpersonal space (i.e. social space within personal comfort area) are well documented, it is not clear whether they also extend to peripersonal space (i.e. reaching space). Indeed, no study has directly compared these spaces in relation to

  11. The influence of the nitrogen admixture on the evolution of a deuterium pinch column

    Energy Technology Data Exchange (ETDEWEB)

    Kubes, P.; Cikhardtova, B.; Cikhardt, J.; Klir, D.; Kravarik, J.; Rezac, K.; Kortanek, J. [Czech Technical University, 166-27 Prague (Czech Republic); Paduch, M.; Zielinska, E. [Institute of Plasma Physics and Laser Microfusion, 01-497 Warsaw (Poland); Sadowski, M. J. [Institute of Plasma Physics and Laser Microfusion, 01-497 Warsaw (Poland); National Centre for Nuclear Research, 05-400 Otwock-Świerk (Poland); Tomaszewski, K. [ACS Ltd., 01-497 Warsaw (Poland)

    2016-08-15

    The application of a mixture of nitrogen and deuterium for the gas-puffing along the anode axis in deuterium plasma-focus discharges, as carried out at megaampere-level currents, enabled observations of the filamentary structure, and the decrease in the transformation velocity of the plasma column to be performed. It made possible to investigate the instability evolution during the production of hard X-rays and fast neutrons in more detail. The constriction of a plasma column transforms itself during the final phase of the compression into one or more small dense plasmoid-like structures which are separated by narrow necks. During the next phase, these structures start to decay by an expansion, in which a part of the plasma volume maintains its compactness. This evolution is explained by an increase and later decrease in the internal poloidal current component by reconnections of the associated magnetic lines, which are responsible for the acceleration of electron and ion beams.

  12. About influencing specificity of space flights on the information, perceived by astronauts

    Science.gov (United States)

    Prisniakova, L.; Prisniakov, V.

    Research of influence of gravitational fields on character of decision-making by the cosmonaut in reply to the information acting to him is the purpose of the report. The magnitude of perceived consciously of flow of the information for all sensory systems (visual, acoustical, somatosensory, chemical, kinaesthetical, balance of a head and time) is analysed. The coefficient of transformation of the incoming information from an environment to the person and the information realized by him has been received equal κ =105. As the susceptibility of the cosmonaut to the incoming of information to him depends on his temperament, the hypothesis about modification of his temperament and accordingly about modification of character of activity of the cosmonaut during duration of flight is voiced. B.Tsukanov's hypothesis is used, that as a measure of mobility of nervous system (temperament) of the person it is possible to use of the magnitude of subjectively experienced time τz. The formula for definition τz is offered using the period of an of alpha waves. The known data of authors, on the one hand, about communication of a time constant of information processing in memory of person T with frequency of alpha waves f and on the other hand, on its relationship with overloads j were used. This dependence of the period of fluctuations of alpha waves Tα from overloads (or microgravitation) enable to find magnitude of change of individually experienced time τ z at action of distinct from normal gravitational fields. The increase of this value of magnitude in case of presence of overloads can lead to to uncontrollable change of behaviour of cosmonauts in connection by erroneous perception of time and space. Acknowledgement to this is display by pilots - verifiers of "loss of orientation''.This result essentially supplements an explanation of this effect which was considered by authors in Houston on the basis of the analysis of the basic psychophysical law. Dependence of change

  13. The influence of He/dpa ratio and displacement rate on microstructural evolution: a comparison of theory and experiment

    International Nuclear Information System (INIS)

    Katoh, Yutai; Stoller, Roger E.; Kohno, Yutaka; Kohyama, Akira

    1994-01-01

    A kinetic model was developed to investigate the influence of the displacement rate and helium generation rate on microstructural evolution in austenitic stainless steels. The model integrates the rate equations describing the evolution of point defects, small point defect clusters, helium-vacancy clusters, and the larger cavity size distribution that is responsible for observable swelling. Cavity (bubble) nucleation is accounted for by the helium-vacancy cluster evolution, while void formation occurs when bubbles grow beyond a critical size in the larger cavity distribution. A series of ion irradiation experiments were used to both calibrate the model and to provide a comparison between model predictions and experimental observations. The experiments involved single and dual-beam irradiations of solution annealed AISI-316 stainless steel at 873 K. The displacement rates were in the range of 2x10 -3 to 1x10 -2 dpa/s and the helium-to-dpa ratios were in the range of 0 to 50 appm He/dpa. The maximum displacement dose was 25 dpa. The experiments revealed a significant effect of helium on both the dislocation structure and the cavity distribution. The model predictions of helium effects over a broad range of He/dpa ratios and displacement rates were consistent with experimental observations. ((orig.))

  14. Factors influencing malignant evolution and long-term survival in solitary fibrous tumours of the pleura

    OpenAIRE

    Rodríguez-González, Marta; Novoa, Nuria M.; Gomez, Maria T.; García, Juan L.; Ludeña, María Dolores

    2014-01-01

    Solitary pleuro-pulmonary fibrous tumours are relatively uncommon neoplasms that are difficult to manage therapeutically and which, cytogenetically, have been poorly studied. The aim of the present work was to analyse the characteristics of a series of consecutive operated solitary pleural fibrous tumours in an attempt to discover a malignant pattern of evolution. This was a retrospective observational study of 19 cases. Samples were studied for clinical, histological, immunohistochemical and...

  15. Outcome of patients in acute poisoning with ethylene glycol - factors which may have influence on evolution

    OpenAIRE

    Tanasescu, A; Macovei, RA; Tudosie, MS

    2014-01-01

    Introduction. Intoxication with ethylene glycol occurs as a result of intentional ingestion in suicide attempts or accidentally. Clinical ethylene glycol poisoning is not specific and occurs in many poisoning cases therefore the diagnosis is difficult. Early diagnostic and establishment of therapy are very important for a favorable evolution. The mortality rate of ethylene glycol intoxication ranges between 1 and 22% depending on the amount of alcohol ingestion and the time period between alc...

  16. Wind-tunnel modelling of the tip-speed ratio influence on the wake evolution

    Science.gov (United States)

    Stein, Victor P.; Kaltenbach, Hans-Jakob

    2016-09-01

    Wind-tunnel measurements on the near-wake evolution of a three bladed horizontal axis wind turbine model (HAWT) in the scale 1:O(350) operating in uniform flow conditions and within a turbulent boundary layer at different tip speed ratios are presented. Operational conditions are chosen to exclude Reynolds number effects regarding the turbulent boundary layer as well as the rotor performance. Triple-wire anemometry is used to measure all three velocity components in the mid-vertical and mid-horizontal plane, covering the range from the near- to the far-wake region. In order to analyse wake properties systematically, power and thrust coefficients of the turbine were measured additionally. It is confirmed that realistic modelling of the wake evolution is not possible in a low-turbulence uniform approach flow. Profiles of mean velocity and turbulence intensity exhibit large deviations between the low-turbulence uniform flow and the turbulent boundary layer, especially in the far-wake region. For nearly constant thrust coefficients differences in the evolution of the near-wake can be identified for tip speed ratios in the range from 6.5 to 10.5. It is shown that with increasing downstream distances mean velocity profiles become indistinguishable whereas for turbulence statistics a subtle dependency on the tip speed ratio is still noticeable in the far-wake region.

  17. THE EVOLUTION OF PRIVATE LOANS IN ROMANIA AND EXAMINATION OF SOME FACTORS OF INFLUENCE

    Directory of Open Access Journals (Sweden)

    MIHAI MIEILĂ

    2017-08-01

    Full Text Available The paper analyzes the evolution of Romanian private loans, in national currency (lei, granted to households and non-financial corporations in the period between July 2005 and April 2017. In this context, after reviewing the importance of credit within the context of national economy is presented the evolution of some factors considered as influential upon the evolution of credit. These factors are, namely: the average interest rate of outstanding private loans granted by credit institutions, the average interest rate of outstanding amount of deposits received by credit institutions, the ratio of minimum (or reserve requirements, the interest rate on required reserves and the monetary policy rate. The database was built using the available data from the Statistical Section of the monthly bulletins released by the National Bank of Romania (herein after, referred to as NBR and published on the institution’s website. Every series of data is subject of testing for stationarity, using both the Augmented Dickey-Fuller and Pillips-Perron tests (herein after, referred to as ADF and PP, respectively, and the reported results are presented within the paper. In order to avoid spurious regression, following the stationarization of the data series, an analysis model is put in place and the significant results are subject to further interpretation.

  18. Limited Influence of Oxygen on the Evolution of Chemical Diversity in Metabolic Networks

    Directory of Open Access Journals (Sweden)

    Kazuhiro Takemoto

    2013-10-01

    Full Text Available Oxygen is thought to promote species and biomolecule diversity. Previous studies have suggested that oxygen expands metabolic networks by acquiring metabolites with different chemical properties (higher hydrophobicity, for example. However, such conclusions are typically based on biased evaluation, and are therefore non-conclusive. Thus, we re-investigated the effect of oxygen on metabolic evolution using a phylogenetic comparative method and metadata analysis to reduce the bias as much as possible. Notably, we found no difference in metabolic network expansion between aerobes and anaerobes when evaluating phylogenetic relationships. Furthermore, we showed that previous studies have overestimated or underestimated the degrees of differences in the chemical properties (e.g., hydrophobicity between oxic and anoxic metabolites in metabolic networks of unicellular organisms; however, such overestimation was not observed when considering the metabolic networks of multicellular organisms. These findings indicate that the contribution of oxygen to increased chemical diversity in metabolic networks is lower than previously thought; rather, phylogenetic signals and cell-cell communication result in increased chemical diversity. However, this conclusion does not contradict the effect of oxygen on metabolic evolution; instead, it provides a deeper understanding of how oxygen contributes to metabolic evolution despite several limitations in data analysis methods.

  19. Influence of mass imperfections on the evolution of standing waves in slowly rotating spherical bodies

    CSIR Research Space (South Africa)

    Shatalov, MY

    2011-01-01

    Full Text Available pattern. We demonstrate how a combination of both qualitative and quantitative analysis (using, interalia, the method of averaging) predicts that the inertial angular rate does not influence changes with time in the amplitudes of the principal...

  20. Numerical Investigation of Influences of Drilling Arrangements on the Mechanical Behavior and Energy Evolution of Coal Models

    Directory of Open Access Journals (Sweden)

    Tong-bin Zhao

    2018-01-01

    Full Text Available Destress drilling method is one of the commonly used methods for mitigating rock bursts, especially in coal mining. To better understand the influences of drilling arrangements on the destress effect is beneficial for rock burst mitigation. This study first introduced the rock burst mitigation mechanism of the destress drilling method and then numerically investigated the influences of drilling arrangements on the mechanical properties of coal models through uniaxial compression tests. Based on the test results, the energy evolution (i.e., the energy dissipation and bursting energy indexes influenced by different drilling arrangements was analyzed. When the drilling diameter, the number of drilling holes in one row, or the number of drilling rows increases, the bearing capacity of specimens nonlinearly decreases, but the energy dissipation index increases. In addition, the drilling diameter or the number of drilling holes in one row affects the failure mode weakly, which is different from that of the number of drilling rows. Consequently, the bursting energy index decreases as increasing the drilling diameter or the number of drilling holes in one row, but as increasing the number of drilling rows, the variation law of bursting energy index is not obvious. At last, the influencing mechanism of drilling arrangement on the rock burst prevention mechanism of the destress drilling method was discussed and revealed.

  1. When do plant radiations influence community assembly? The importance of historical contingency in the race for niche space.

    Science.gov (United States)

    Tanentzap, Andrew J; Brandt, Angela J; Smissen, Rob D; Heenan, Peter B; Fukami, Tadashi; Lee, William G

    2015-07-01

    Plant radiations are widespread but their influence on community assembly has rarely been investigated. Theory and some evidence suggest that radiations can allow lineages to monopolize niche space when founding species arrive early into new bioclimatic regions and exploit ecological opportunities. These early radiations may subsequently reduce niche availability and dampen diversification of later arrivals. We tested this hypothesis of time-dependent lineage diversification and community dominance using the alpine flora of New Zealand. We estimated ages of 16 genera from published phylogenies and determined their relative occurrence across climatic and physical gradients in the alpine zone. We used these data to reconstruct occupancy of environmental space through time, integrating palaeoclimatic and palaeogeological changes. Our analysis suggested that earlier-colonizing lineages encountered a greater availability of environmental space, which promoted greater species diversity and occupancy of niche space. Genera that occupied broader niches were subsequently more dominant in local communities. An earlier time of arrival also contributed to greater diversity independently of its influence in accessing niche space. We suggest that plant radiations influence community assembly when they arise early in the occupancy of environmental space, allowing them to exclude later-arriving colonists from ecological communities by niche preemption. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  2. Origin and Evolution of Magnetic Field in PMS Stars: Influence of Rotation and Structural Changes

    Energy Technology Data Exchange (ETDEWEB)

    Emeriau-Viard, Constance; Brun, Allan Sacha, E-mail: constance.emeriau@cea.fr, E-mail: sacha.brun@cea.fr [Laboratoire AIM Paris-Saclay CEA/DSM—CNRS—Université Paris Diderot, IRFU/DAp CEA Paris-Saclay, F-91191 Gif-sur-Yvette Cedex (France)

    2017-09-01

    During stellar evolution, especially in the pre-main-sequence phase, stellar structure and rotation evolve significantly, causing major changes in the dynamics and global flows of the star. We wish to assess the consequences of these changes on stellar dynamo, internal magnetic field topology, and activity level. To do so, we have performed a series of 3D HD and MHD simulations with the ASH code. We choose five different models characterized by the radius of their radiative zone following an evolutionary track computed by a 1D stellar evolution code. These models characterized stellar evolution from 1 to 50 Myr. By introducing a seed magnetic field in the fully convective model and spreading its evolved state through all four remaining cases, we observe systematic variations in the dynamical properties and magnetic field amplitude and topology of the models. The five MHD simulations develop a strong dynamo field that can reach an equipartition state between the kinetic and magnetic energies and even superequipartition levels in the faster-rotating cases. We find that the magnetic field amplitude increases as it evolves toward the zero-age main sequence. Moreover, the magnetic field topology becomes more complex, with a decreasing axisymmetric component and a nonaxisymmetric one becoming predominant. The dipolar components decrease as the rotation rate and the size of the radiative core increase. The magnetic fields possess a mixed poloidal-toroidal topology with no obvious dominant component. Moreover, the relaxation of the vestige dynamo magnetic field within the radiative core is found to satisfy MHD stability criteria. Hence, it does not experience a global reconfiguration but slowly relaxes by retaining its mixed stable poloidal-toroidal topology.

  3. Positive and purifying selection influence the evolution of doublesex in the Anastrepha fraterculus species group.

    Directory of Open Access Journals (Sweden)

    Iderval S Sobrinho

    Full Text Available The gene doublesex (dsx is considered to be under strong selective constraint along its evolutionary history because of its central role in somatic sex differentiation in insects. However, previous studies of dsx used global estimates of evolutionary rates to investigate its molecular evolution, which potentially miss signals of adaptive changes in generally conserved genes. In this work, we investigated the molecular evolution of dsx in the Anastrepha fraterculus species group (Diptera, Tephritidae, and test the hypothesis that this gene evolved solely by purifying selection using divergence-based and population-based methods. In the first approach, we compared sequences from Anastrepha and other Tephritidae with other Muscomorpha species, analyzed variation in nonsynonymous to synonymous rate ratios (dN/dS in the Tephritidae, and investigated radical and conservative changes in amino acid physicochemical properties. We show a general selective constraint on dsx, but with signs of positive selection mainly in the common region. Such changes were localized in alpha-helices previously reported to be involved in dimer formation in the OD2 domain and near the C-terminal of the OD1 domain. In the population-based approach, we amplified a region of 540 bp that spanned almost all of the region common to both sexes from 32 different sites in Brazil. We investigated patterns of selection using neutrality tests based on the frequency spectrum and locations of synonymous and nonsynonymous mutations in a haplotype network. As in the divergence-based approach, these analyses showed that dsx has evolved under an overall selective constraint, but with some events of positive selection. In contrast to previous studies, our analyses indicate that even though dsx has indeed evolved as a conserved gene, the common region of dsx has also experienced bouts of positive selection, perhaps driven by sexual selection, during its evolution.

  4. Evolution of mechanical characteristics and permeability of clayey materials under the influence of thermal loadings

    International Nuclear Information System (INIS)

    Boucly-Norotte, V.

    1991-01-01

    This research thesis reports the study of the effects on a long term of temperature variations on the volume and texture of clayey soils, notably with respect to their initial petro-physical and petro-graphical characteristics, and to their consolidation state. From an experimental point of view, this research is based on the monitoring of the volume strain and of the permeability of samples placed in an oedometric cell and submitted to thermal loadings within the 20 C - 110 C range. A thorough texture investigation (mercury-based porosimetry, observation by scanning electronic microscopy, and so on) before and after testing allows the evolution of material texture to be assessed [fr

  5. Influence of Humans on Evolution and Mobilization of Environmental Antibiotic Resistome

    Science.gov (United States)

    Gaze, William H.; Krone, Stephen M.; Larsson, D.G. Joakim; Li, Xian-Zhi; Robinson, Joseph A.; Simonet, Pascal; Smalla, Kornelia; Timinouni, Mohammed; Topp, Ed; Wellington, Elizabeth M.; Zhu, Yong-Guan

    2013-01-01

    The clinical failure of antimicrobial drugs that were previously effective in controlling infectious disease is a tragedy of increasing magnitude that gravely affects human health. This resistance by pathogens is often the endpoint of an evolutionary process that began billions of years ago in non–disease-causing microorganisms. This environmental resistome, its mobilization, and the conditions that facilitate its entry into human pathogens are at the heart of the current public health crisis in antibiotic resistance. Understanding the origins, evolution, and mechanisms of transfer of resistance elements is vital to our ability to adequately address this public health issue. PMID:23764294

  6. Influence of Fe underlayers on stress evolution of Ti in Ti/Fe multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Li; Thompson, Gregory, E-mail: gthompson@eng.ua.edu [Department of Metallurgical Engineering, The University of Alabama, Tuscaloosa, Alabama 35487-0202 (United States)

    2016-11-15

    A series of 40–2 nm bilayer spacing Ti/Fe multilayers were sputter-deposited. As the length scale of individual Ti layers equaled to 2 nm, Ti phase transforms from a hexagonal close packed (hcp)-to-body centered cubic (bcc) crystal structures for equal layer thicknesses in Ti/Fe multilayers. Further equal reductions in bilayer spacing to less than 1 nm resulted in an additional transformation from a crystalline to amorphous structure. Atom probe tomography reveals significant intermixing between layers which contributes to the observed phase transformations. Real-time, intrinsic growth stress measurements were also performed to relate the adatom mobility to these phase transformations. For the hcp Ti/bcc Fe multilayers of equivalent volume fractions, the multilayers undergo an overall tensile stress state to a compressive stress state with decreasing bilayer thickness for the multilayers. When the above phase transformations occurred, a modest reduction in the overall compressive stress of the multilayer was noted. Depending on the Fe thickness, the Ti growth was observed to be a tensile to compressive growth change to a purely compressive growth for thinner bilayer spacing. Fe retained a tensile growth stress regardless of the bilayer spacing studied.

  7. Measuring the Evolution of Stellar Populations And Gas Metallicity in Galaxies with Far-Infrared Space Spectroscopy

    Science.gov (United States)

    Stacey, Gordon

    power. The rich Herschel/PACS data set is particularly attractive for this study due to its sensitivity and calibration uniformity. We propose to undertake such a study here. An initial search of the Herschel Archive reveals that there are at least 80 galaxies that have been observed in the [NII] 122 µm, [OIII] 52 and/or 88 µm and the [CII] 158 µm line. The primary goal of this proposal is to use these emission lines to study the star formation properties (age, metallicity, initial mass function (IMF) and star formation efficiency) in galaxies in the local Universe. This line of study ties into our overarching research objective which is to understand the evolution of star and galaxy formation over cosmic time. We have begun studying star formation in the early Universe by detecting these lines at high redshifts with our grating spectrometer ZEUS-2 on the APEX telescope, and through ALMA programs. The study we propose here will allow us to confidently apply these spectral probes to studies of high-z galaxies while also providing new insights into the characteristic and process of star-formation of galaxies in the nearby Universe. We will utilize NASA s space astrophysics archives to explore the evolution of stellar populations and the elements over cosmic time. The proposed work is therefore highly relevant to NASA s Strategic goal 1: Expand the frontiers of knowledge, capability, and opportunity in space. , Objective 1.6 Discover how the Universe works, explore how it began and evolved, and search for life on planets around other stars. Since the program involves both graduate and undergraduate students at a research university, we also address Strategic Goal 2 via Objective 2.4: Advance the Nation s STEM education and workforce pipeline by working collaborative with other agencies to engage students, teachers, and faculty in NASA s missions and unique assets.

  8. Influence of Population Variation of Physiological Parameters in Computational Models of Space Physiology

    Science.gov (United States)

    Myers, J. G.; Feola, A.; Werner, C.; Nelson, E. S.; Raykin, J.; Samuels, B.; Ethier, C. R.

    2016-01-01

    The earliest manifestations of Visual Impairment and Intracranial Pressure (VIIP) syndrome become evident after months of spaceflight and include a variety of ophthalmic changes, including posterior globe flattening and distension of the optic nerve sheath. Prevailing evidence links the occurrence of VIIP to the cephalic fluid shift induced by microgravity and the subsequent pressure changes around the optic nerve and eye. Deducing the etiology of VIIP is challenging due to the wide range of physiological parameters that may be influenced by spaceflight and are required to address a realistic spectrum of physiological responses. Here, we report on the application of an efficient approach to interrogating physiological parameter space through computational modeling. Specifically, we assess the influence of uncertainty in input parameters for two models of VIIP syndrome: a lumped-parameter model (LPM) of the cardiovascular and central nervous systems, and a finite-element model (FEM) of the posterior eye, optic nerve head (ONH) and optic nerve sheath. Methods: To investigate the parameter space in each model, we employed Latin hypercube sampling partial rank correlation coefficient (LHSPRCC) strategies. LHS techniques outperform Monte Carlo approaches by enforcing efficient sampling across the entire range of all parameters. The PRCC method estimates the sensitivity of model outputs to these parameters while adjusting for the linear effects of all other inputs. The LPM analysis addressed uncertainties in 42 physiological parameters, such as initial compartmental volume and nominal compartment percentage of total cardiac output in the supine state, while the FEM evaluated the effects on biomechanical strain from uncertainties in 23 material and pressure parameters for the ocular anatomy. Results and Conclusion: The LPM analysis identified several key factors including high sensitivity to the initial fluid distribution. The FEM study found that intraocular pressure and

  9. Influence of asymmetric magnetic perturbation on the nonlinear evolution of double tearing modes

    Science.gov (United States)

    Xiong, G. Z.; Wang, L.; Li, X. Q.; Liu, H. F.; Tang, C. J.; Huang, J.; Zhang, X.; Wang, X. Q.

    2017-06-01

    The effects of asymmetric magnetic perturbation on the triggering and evolution of double tearing modes (DTMs) are investigated using nonlinear magnetohydrodynamics simulations in a slab geometry. We find that for reversed magnetic shear plasmas the resistive reconnection process induced by the initial perturbation at one rational surface can drive a new island at the other rational surface with the same mode number. The four typical states of the mode for the time evolution are found, and include: (i) a linear growth stage; (ii) a linear/nonlinear stable stage; (iii) an interactively driving stage; and (iv) a symmetric DTM stage. These differ from previous simulation results. Moreover, nonlinear DTM growth is found to strongly depend on the asymmetric magnetic perturbation, particularly in the early nonlinear phase. The initial perturbation strength scale of island width suggests that the left island enters into a Sweet-Parker growth process when the right island is sufficiently large to effectively drive the other. These results predict that although externally applied magnetic perturbations can suppress the neoclassical tearing mode they can also trigger new instabilities such as asymmetric DTMs.

  10. Influence of asymmetric magnetic perturbation on the nonlinear evolution of double tearing modes

    International Nuclear Information System (INIS)

    Xiong, G Z; Liu, H F; Huang, J; Wang, X Q; Wang, L; Li, X Q; Tang, C J; Zhang, X

    2017-01-01

    The effects of asymmetric magnetic perturbation on the triggering and evolution of double tearing modes (DTMs) are investigated using nonlinear magnetohydrodynamics simulations in a slab geometry. We find that for reversed magnetic shear plasmas the resistive reconnection process induced by the initial perturbation at one rational surface can drive a new island at the other rational surface with the same mode number. The four typical states of the mode for the time evolution are found, and include: (i) a linear growth stage; (ii) a linear/nonlinear stable stage; (iii) an interactively driving stage; and (iv) a symmetric DTM stage. These differ from previous simulation results. Moreover, nonlinear DTM growth is found to strongly depend on the asymmetric magnetic perturbation, particularly in the early nonlinear phase. The initial perturbation strength scale of island width suggests that the left island enters into a Sweet–Parker growth process when the right island is sufficiently large to effectively drive the other. These results predict that although externally applied magnetic perturbations can suppress the neoclassical tearing mode they can also trigger new instabilities such as asymmetric DTMs. (paper)

  11. Quality parameters of wine grape varieties under the influence of different vine spacing and training systems

    Directory of Open Access Journals (Sweden)

    O. Tkachenko

    2017-06-01

    Full Text Available Physicochemical and biochemical indices, which characterize quality of white wine grape varieties Zagrey and Aromatnyi of selection of NNC «IV&W named after V. Ye. Tairov», (harvest of 2016 were determined. The field trial which includes various variants of planting density and vine training systems, made it possible to study the influence of viticulture practices on the criteria of carbohydrate-acid and phenolic complex, oxidative enzyme system of grapes. Low-density plantings of Aromatnyi variety (2222 vines per ha were characterized by harvest that slightly exceeded the grapes obtained from dense plantations (4000 vines per ha in terms of carbohydrate-acid and phenolic complexes. The most optimal in terms of the mass concentration of sugars, phenolic substances, polymer forms, macerating ability of must, activity of oxidizing enzyme system was cultivation of this variety on a 160 cm – high trunk. Growing grapes of Zagrey variety with vine spacing, corresponding to 4000 plants per ha, contributed to obtaining harvest with optimal parameters of carbohydrate-acid complex, low technological reserve and mass concentration of phenolic compounds, moderate macerating ability and activity of monophenol monooxygenase in must. Training vines of this variety on a 40 cm high trunk with vertical shoot positioning led to significant deterioration of grape quality due to increased content of phenolic substances and their polymer forms, high macerating capacity of must.

  12. The influence of flywheel micro vibration on space camera and vibration suppression

    Science.gov (United States)

    Li, Lin; Tan, Luyang; Kong, Lin; Wang, Dong; Yang, Hongbo

    2018-02-01

    Studied the impact of flywheel micro vibration on a high resolution optical satellite that space-borne integrated. By testing the flywheel micro vibration with six-component test bench, the flywheel disturbance data is acquired. The finite element model of the satellite was established and the unit force/torque were applied at the flywheel mounting position to obtain the micro vibration data of the camera. Integrated analysis of the data of the two parts showed that the influence of flywheel micro vibration on the camera is mainly concentrated around 60-80 Hz and 170-230 Hz, the largest angular displacement of the secondary mirror along the optical axis direction is 0.04″ and the maximum angular displacement vertical to optical axis is 0.032″. After the design and installation of vibration isolator, the maximum angular displacement of the secondary mirror is 0.011″, the decay rate of root mean square value of the angular displacement is more than 50% and the maximum is 96.78%. The whole satellite was suspended to simulate the boundary condition on orbit; the imaging experiment results show that the image motion caused by the flywheel micro vibrationis less than 0.1 pixel after installing the vibration isolator.

  13. Influence of vaccine strains on the evolution of canine distemper virus.

    Science.gov (United States)

    da Fontoura Budaszewski, Renata; Streck, André Felipe; Nunes Weber, Matheus; Maboni Siqueira, Franciele; Muniz Guedes, Rafael Lucas; Wageck Canal, Cláudio

    2016-07-01

    Canine distemper virus (CDV) is a major dog pathogen belonging to the genus Morbillivirus of the family Paramyxoviridae. CDV causes disease and high mortality in dogs and wild carnivores. Although homologous recombination has been demonstrated in many members of Paramyxoviridae, these events have rarely been reported for CDV. To detect potential recombination events, the complete CDV genomes available in GenBank up to June 2015 were screened using distinct algorithms to detect genetic conversions and incongruent phylogenies. Eight putative recombinant viruses derived from different CDV genotypes and different hosts were detected. The breakpoints of the recombinant strains were primarily located on fusion and hemagglutinin glycoproteins. These results suggest that homologous recombination is a frequent phenomenon in morbillivirus populations under natural replication, and CDV vaccine strains might play an important role in shaping the evolution of this virus.

  14. Influence of coherent structures on the evolution of an axisymmetric turbulent jet

    Science.gov (United States)

    Breda, Massimiliano; Buxton, Oliver R. H.

    2018-03-01

    The role of initial conditions in affecting the evolution toward self-similarity of an axisymmetric turbulent jet is examined. The jet's near-field coherence was manipulated by non-circular exit geometries of identical open area, De2, including a square and a fractal exit, for comparison with a classical round orifice jet. Hot-wire anemometry and 2D-planar particle image velocimetry experiments were performed between the exit and a location 26De downstream, where the Reynolds stress profiles are self-similar. This study shows that a fractal geometry significantly changes the near-field structure of the jet, breaking up the large-scale coherent structures, thereby affecting the entrainment rate of the background fluid into the jet stream. It is found that many of the jet's turbulent characteristics scale with the number of eddy turnover times rather than simply the streamwise coordinate, with the entrainment rate (amongst others) found to be comparable across the different jets after approximately 3-4 eddies have been overturned. The study is concluded by investigating the jet's evolution toward a self-similar state. No differences are found for the large-scale spreading rate of the jets in the weakly self-similar region, so defined as the region for which some, but not all of the terms of the mean turbulent kinetic energy equation are self-similar. However, the dissipation rate of the turbulent kinetic energy was found to vary more gradually in x than predicted according to the classical equilibrium theories of Kolmogorov. Instead, the dissipation was found to vary in a non-equilibrium fashion for all three jets tested.

  15. Morphological evolution of the Maipo River in central Chile: Influence of instream gravel mining

    Science.gov (United States)

    Arróspide, Felipe; Mao, Luca; Escauriaza, Cristián

    2018-04-01

    Instream gravel mining is one of the most important causes of channel degradation in South America, specifically in rivers located near large metropolitan areas with rapidly growing cities, where no river management strategies exist. In the western region of the continent, many of these rivers belong to Andean systems, in which significant parts of the watersheds are located in mountain areas at high altitude, with considerable seasonal rainfall variability and steep channel slopes. In these rivers, gravel mining has produced significant incision of the channels with serious physical and ecological consequences, affecting habitats, modifying the supply and transport of sediments, and amplifying the risk to infrastructure in and around the channel during floods. In spite of the degraded conditions of many channels, no quantitative studies of the geomorphic impacts of gravel mining have been carried out in the region, mostly because of the insufficient and sparse data available. In this investigation we perform an analysis of the morphodynamic evolution in a section of the Maipo River in the metropolitan region of Santiago, Chile. This river is economically the most important in the country, as it provides drinking and irrigation water to urban and rural areas, is utilized by the energy generation industry, and runs along and below critical infrastructure. We have collected and analyzed data from 1954 to 2015, during which the city population increased by more than 5 million inhabitants whose presence accelerated land use changes. The analysis shows a rapid morphological evolution of the channel where in 31 years effects such as: river sections showing incision of up to 20 m, an increase of the area affected by gravel mining from 86.62 to 368.13 ha, and a net erosion volume of 39.4 million m3 can be observed. This work yields quantitative information on the consequences of gravel mining in the Maipo River, providing the necessary data to develop an integrated

  16. Time evolution of the fission-decay width under the influence of dissipation

    International Nuclear Information System (INIS)

    Jurado, B.; Schmidt, K.H.; Benlliure, J.

    2002-12-01

    Different analytical approximations to the time-dependent fission-decay width used to extract the influence of dissipation on the fission process are critically examined. Calculations with a new, highly realistic analytical approximation to the exact solution of the Fokker-Planck equation sheds doubts on previous conclusions on the dissipation strength made on the basis of less realistic approximations. (orig.)

  17. Cyclical Evolution of Nursing Education and Profession in Iran: Religious, Cultural, and Political Influences.

    Science.gov (United States)

    Mura, Pari; Mura, Aubin

    1995-01-01

    Nursing education in Iran has been influenced by cycles of religious and political change, including fluctuations in women's status, the modernization attempts of the Pahlavi Dynasty, and the shift from secular science-based education and health care back to a system based on religious and cultural principles in the Islamic Republic of Iran. (SK)

  18. Generalized free-space diffuse photon transport model based on the influence analysis of a camera lens diaphragm.

    Science.gov (United States)

    Chen, Xueli; Gao, Xinbo; Qu, Xiaochao; Chen, Duofang; Ma, Xiaopeng; Liang, Jimin; Tian, Jie

    2010-10-10

    The camera lens diaphragm is an important component in a noncontact optical imaging system and has a crucial influence on the images registered on the CCD camera. However, this influence has not been taken into account in the existing free-space photon transport models. To model the photon transport process more accurately, a generalized free-space photon transport model is proposed. It combines Lambertian source theory with analysis of the influence of the camera lens diaphragm to simulate photon transport process in free space. In addition, the radiance theorem is also adopted to establish the energy relationship between the virtual detector and the CCD camera. The accuracy and feasibility of the proposed model is validated with a Monte-Carlo-based free-space photon transport model and physical phantom experiment. A comparison study with our previous hybrid radiosity-radiance theorem based model demonstrates the improvement performance and potential of the proposed model for simulating photon transport process in free space.

  19. Influence of cusps and intersections on the calculation of the Wilson loop in ν-dimensional space

    International Nuclear Information System (INIS)

    Bezerra, V.B.

    1984-01-01

    A discussion is given about the influence of cusps and intersections on the calculation of the Wilson Loop in ν-dimensional space. In particular, for the two-dimensional case, it is shown that there are no divergences. (Author) [pt

  20. Transgressive Shoreface Response in the Mississippi River DeltaShoreface Sediment Budget Influence on Barrier Island Evolution, Louisiana, USA

    Science.gov (United States)

    Beasley, B.; Georgiou, I. Y.; Miner, M. D.

    2017-12-01

    In Louisiana barrier islands are undergoing rapid morphological change due to shoreface retreat and increasing bay tidal prism driven by high rates of relative sea-level rise (RSLR) (1 cm/yr) and interior wetland loss, respectively. Previous works utilized historical region-scale bathymetry change and shoreline change analyses to assess large-scale coastal evolution. However, more localized assessments considering the role of sediment transport processes in regional evolution are lacking. This is essential to predicting coastal change trajectories and allocating limited sand resources for nourishment. Using historic bathymetric and shoreline data dating to the 1890s for the Louisiana coast, 100-m spaced shore-normal transects were created to track meter-scale elevation change for 1890, 1930, 1980, 2006, and 2015. An automated framework was used to quantify and track barrier island evolution parameters such as shoreline change, area, width, bathymetric contour migration, and shoreface slope. During the 125 yr analysis period, shoreline erosion mean rates slowed from 12 to 6 m/yr while lower shoreface migration mean rates increased from 5 to 25 m/yr. Locally, retreat rates for the Caminada Headland upper shoreface slowed from 18 to 8 m/yr while lower shoreface retreat rates increased from 8 to 14m/yr. The Timbalier Islands experienced increased migration rates along the entire shoreface, while the lower shoreface of the Isles Dernieres transitioned from progradational to erosional (-5 m/yr in 1890 to 20 m/yr in 2006). Our analysis suggests that although shoreline erosion rates decreased, overall landward migration of the barrier system increased as the shoreface steepened. Our results illustrate that monitoring subaerial island erosion rates are insufficient for evaluating regional dynamics of transgressive coastal systems. The longevity of barriers appears diminished due to a reduction in the shoreface sediment available and further corroborates the role of the

  1. Influence of Kuroshio SST front in the East China Sea on the climatological evolution of Meiyu rainband

    Science.gov (United States)

    Xu, Mimi; Xu, Haiming; Ren, Huijun

    2018-02-01

    The influence of Kuroshio sea surface temperature (SST) front in the East China Sea (ECS) on the temporal evolution of climatological Meiyu rainband was investigated using a suite of high-resolution satellite observations and a reanalysis dataset from 2000 to 2011. During the northward seasonal march of Meiyu rainband from the warmer flank of the SST front to the colder flank, the climatological rainband strength weakened substantially despite large-scale environment became more conducive to intensify precipitation. A sharp reduction in occurrence frequency of precipitation with relatively shallower depth and smaller intensity was responsible for the weakening of Meiyu rainband. During the northward migration of Meiyu rainband, individual precipitation events became deeper and more intensive, and the contribution of convective precipitation to the rainband was enhanced, associated with the seasonal northward extension of high convective instability region over the ECS. The characteristics of Meiyu rainband evolution were generally supported by cloud observations. When Meiyu rainband was located on the warmer flank of the SST front, local enhanced mean surface wind convergence and variance of convergence at synoptic timescale by the warm SST of the Kuroshio favored strong surface convergence that may trigger precipitation. A detailed moisture budget analysis revealed that the major part of moisture for Meiyu precipitation was supplied by low-level wind convergence, with much smaller contribution from moisture advection. The variation of climatological precipitation associated with Meiyu northward migration depended on SST modulation of both surface evaporation and low-level moisture convergence over the ECS.

  2. The Evolution of Early-Stage Entrepreneurial Activity Influencing Factors in Romania

    Directory of Open Access Journals (Sweden)

    Tünde Petra PETRU

    2010-07-01

    Full Text Available The aim of the article is to analyze the main influencing factors of the probability of becoming an early-stage entrepreneur in Romania. The analyzed factors are: gender, age, education, household income, work status, network, opportunity perception, perception regarding the trust in own entrepreneurial skills, perception on the society’s appreciation regarding the principle of equality in life standard, perception on the society’s appreciation regarding the entrepreneurial career, perception on the proper promotion of entrepreneurial successes by mass media. We estimate a logit model for each year of the 2007-2009 period and we study the main influencing perceptional and sociodemographic factors, based on the Global Entrepreneurship Monitor (GEM Adult Population Survey database for Romania.

  3. Influence of impurities on the evolution of vacancy-type defects in neutron-irradiated nickel

    International Nuclear Information System (INIS)

    Druzhkov, A.P.; Perminov, D.A.; Arbuzov, V.L.

    2012-01-01

    Highlights: ► We study, by means of PAS, the effects of purity on damage evolution in neutron-irradiated Ni at 330 K. ► Impurity carbon atoms in solution decrease the cascade efficiency during irradiation. ► C–V complexes are formed on the recovery stage III in impure Ni irradiated with 10 −4 dpa. ► The formation of V-loops and SFTs dominate on stage III with increasing dose level. ► The thermal stability of SFTs in impure Ni is similar to that in pure Ni. - Abstract: In order to investigate the effect of impurities on vacancy defect evolution in nickel, specimens with high (5N) and technical (3N) purity were neutron-irradiated at ∼330 K in the IVV-2M reactor (Russia) to fluencies in the range of 1 × 10 21 –1 × 10 23 n/m 2 (E > 0.1 MeV) corresponding to displacement dose levels in the range of about 0.0001–0.01 dpa and subsequently stepwise annealed to about 900 K. The specimens of Ni with different purities were characterized both in as-irradiated state as well as after post-irradiation annealing by positron annihilation spectroscopy. The formation of three-dimensional vacancy clusters (3D-VCs) in cascades was observed under neutron irradiation. The density and size of 3D-VCs depended not only on dose level, but also on purity. The population of 3D-VCs in the technical Ni is lower than that in the high-purity Ni. 3D-VCs collapse into secondary-type clusters (stacking fault tetrahedra (SFTs) and vacancy loops) during stepwise annealing at 350–450 K (stage III in Ni). The suppression of secondary cluster formation in 3N Ni is attributed to an effective vacancy interaction with impurity carbon atoms, which based on a relatively large vacancy–carbon atom binding energy (0.32–0.35 eV). The trapping of vacancies released at the collapse of 3D-VCs by the interstitial impurity atoms dominates at low irradiation dose level (10 −4 dpa). Thus, we found that carbon impurity atoms have strong effects both on the primary vacancy-type defect

  4. Genomic analysis of codon usage shows influence of mutation pressure, natural selection, and host features on Marburg virus evolution.

    Science.gov (United States)

    Nasrullah, Izza; Butt, Azeem M; Tahir, Shifa; Idrees, Muhammad; Tong, Yigang

    2015-08-26

    The Marburg virus (MARV) has a negative-sense single-stranded RNA genome, belongs to the family Filoviridae, and is responsible for several outbreaks of highly fatal hemorrhagic fever. Codon usage patterns of viruses reflect a series of evolutionary changes that enable viruses to shape their survival rates and fitness toward the external environment and, most importantly, their hosts. To understand the evolution of MARV at the codon level, we report a comprehensive analysis of synonymous codon usage patterns in MARV genomes. Multiple codon analysis approaches and statistical methods were performed to determine overall codon usage patterns, biases in codon usage, and influence of various factors, including mutation pressure, natural selection, and its two hosts, Homo sapiens and Rousettus aegyptiacus. Nucleotide composition and relative synonymous codon usage (RSCU) analysis revealed that MARV shows mutation bias and prefers U- and A-ended codons to code amino acids. Effective number of codons analysis indicated that overall codon usage among MARV genomes is slightly biased. The Parity Rule 2 plot analysis showed that GC and AU nucleotides were not used proportionally which accounts for the presence of natural selection. Codon usage patterns of MARV were also found to be influenced by its hosts. This indicates that MARV have evolved codon usage patterns that are specific to both of its hosts. Moreover, selection pressure from R. aegyptiacus on the MARV RSCU patterns was found to be dominant compared with that from H. sapiens. Overall, mutation pressure was found to be the most important and dominant force that shapes codon usage patterns in MARV. To our knowledge, this is the first detailed codon usage analysis of MARV and extends our understanding of the mechanisms that contribute to codon usage and evolution of MARV.

  5. Unraveling the controls on biogeomorphic succession: the influence of groundwater, soil and geomorphic setting on bio-geomorphic channel evolution

    Science.gov (United States)

    Bätz, Nico; Verrecchia, Eric P.; Lane, Stuart N.

    2017-04-01

    Braided rivers are characterized by high rates of morphological change. However, despite the potential for frequent disturbance, vegetated patches may develop within this system and influence long-term channel dynamics and channel patterns through the "engineering effects" of biogeomorphic succession. The stabilizing effect of developing vegetation on morphological change has been widely shown by flume experiments and (historic) aerial pictures analysis. Thus, there is a balance between disturbance and stabilization, mediated through biogeomorphic succession, that may determine the long-term geomorphic and biogeomorphic evolution of the river. Research has addressed how changes in disturbance frequency affect river channel pattern, but much less has been done to understand what influences the rate of biogeomorphic succession and how it affects river morphodynamics. This study explores the complex pattern of ambient conditions in braided river systems driving the rate of biogeomorphic succession. In particular, we focus on the interplay between groundwater access, soil formation, disturbance frequency and geomorphic setting, in defining what drives vegetation succession rates and its long-term implications on channel pattern evolution. We studied these feedbacks in a transitional gravel-bed river system (braided, wandering, meandering) close to Geneva (Switzerland) - the Allondon River. Results show that, at the beginning of the succession, humification plays a negative role on local ambient conditions necessary for sprouting. Successful vegetation establishment is then related positively to humification, but also to higher disturbance rates. The third biogeomorphic phase, with the highest feedbacks on river morphology, appears to be mainly driven by groundwater access, which in turn defines the rates of humification in this gravelly environment. This in turn defines the decadal morphological response of the channel after a reduction in disturbance frequency over

  6. DSC (Differential Scanning Calorimerty used to follow the evolution of W/O emulsions versus time on ground and in space in the ISS

    Directory of Open Access Journals (Sweden)

    Drelich Audrey

    2018-01-01

    Full Text Available The evolution of W/O emulsion versus time in microgravity conditions has been studied in the framework of the FASES (Fundamental and Applied Studies on Emulsion Stability project sponsored by the European Space Agency (ESA. The objective of this study was to investigate the evolution of W/O emulsions made of water + paraffin oil + SPAN 80® under purely diffusive conditions (no gravity driven effects and to compare with evolution of similar emulsions observed on ground. A correlation between the state of dispersion of water and either the freezing temperature during cooling, or the freezing time at a fixed temperature was used to follow the emulsion evolution versus time. For that purpose, two identical calorimeters were built by Airbus (formerly EADS with the support of the French company SETARAM: The Flight Model (FM located onboard the International Space Station (ISS and the Engineering Model (EM located at the TELESPAZIO Centre in Naples. Dedicated cells were filled on ground with different formulations of W/O emulsions and identical experiments were performed with the FM and the EM models in order to highlight the differences in emulsion evolution. On ground, the experiments were performed by cooling and heating the calorimeter between 40 °C and −60 °C but due to technical constraints in the FM, the experiments performed in the FSL (Fluid Science Laboratory of the ISS were limited to a lowest temperature of −22 °C. The results obtained with the FM confirmed the formation of emulsions in the dedicated cell with the selected stirring system in space. These results also demonstrated that it is possible to detect the freezing and the melting of the water droplets with the designed calorimeter either during cooling and heating phases or versus time during a temperature holding period at −22 °C. Furthermore, the comparison between both results obtained with the EM on ground and with the FM in space revealed distinct

  7. Characterization of the factors having an influence on the evolution of the EPR signal of irradiated alanine

    International Nuclear Information System (INIS)

    Feaugas-Le-Berre, Valerie

    1999-01-01

    EPR/alanine dosimetry has been used by the LNHB (Laboratoire National Henri Becquerel) since many years for applied metrology. This technic is based on the measurement of the EPR signal of the free radicals induced in alanine by irradiation. The aim of this work is to characterize the factors having an influence on the evolution of the amplitude of the EPR signal of irradiated alanine to limit the uncertainties on the determination of the absorbed dose. The first step of this work has been the choice of the dosimeter. A bibliographic study completed by experiments on the response of alanine isomers to the dose and on its stability with time has lead us to choose L-α-alanine powder as dosimeter. The influence of the recording parameter of the spectrometer on the characteristics of the EPR spectrum has then been studied. This has enabled us to optimize the recording conditions of EPR spectra. As the angular anisotropy of the EPR signal limits the measurements reproducibility, an experimental protocol has been defined to solve this problem. The repeatability of the measurements has been enhanced by modifying the spectrometer and using an internal standard constituted of single crystals of CuSO 4 .5H 2 O. As the amplitude of the EPR signal is sensitive to the measurement temperature, a method of normalization of the results to 20 C has been determined. We have studied the influence of an irradiation parameter and of environmental parameters. We have shown that the EPR signal amplitude increases with irradiation temperature. The EPR signal amplitude and its evolution vary strongly with storage conditions (temperature and moisture) of the dosimeter before and after irradiation. The presence of moisture in alanine powder leads to a loss of signal amplitude. The dosimeters exposition to light also entails a loss of amplitude. Oxygen does not influence the EPR spectrum of alanine. We have noticed that the EPR signal amplitude of samples stored in absence of moisture

  8. Influence of vacuum space on formation of potential sheath in plasmas

    International Nuclear Information System (INIS)

    Uhm, H.S.

    1997-01-01

    Properties of potential sheaths developed in plasmas are investigated in terms of the plasma Debye length and the dimension of vacuum space. Biased plasma potential and the potential profile depend very sensitively on the geometrical configuration of plasma and vacuum space. The potential sheath is never developed near electrodes in high-density plasmas where the Debye length is much less than the dimension of the vacuum space. In this case, most of the potential drops occur in the vacuum space and almost no electric field exists inside the plasma. Parametric investigation of the potential sheath in terms of the vacuum-space and plasma dimensions is carried out. (orig.)

  9. Influence of electron irradiation on internal friction and structure evolution of polymer composites

    International Nuclear Information System (INIS)

    Ismailova, G.A.

    2007-01-01

    Full text: Important qualitative information on structural evolution and radiation alterations in polymer materials under the action of ionizing radiation can be obtained from the analysis of the temperature dependences of internal friction. Changing of internal friction parameters of relax maxima during irradiation is qualitative degree parameter of radiation scission-cross linking of the polymer molecules. In this work, the general phenomenological approach is realized by introduction of the effective 'observed' parameters into the simple kinetic equations. The applicability of such approach is justified by the fact that kinetics of both internal friction and scission-cross linking processes can be characterized by the same effective parameters. Temperature dependences of internal friction are experimentally studied in epoxy irradiated by 2.5 MeV pulse electron beam to different doses (D=3 MGy, 6 MGy and 9 MGy). Time dependences of internal friction characteristics associated with radiation-induced processes of polymer scission and cross-linking are analyzed and discussed. Experimental data on kinetics of structural transformations in epoxy are interpreted on the base of analytical solutions of differential equations for free radical accumulation during and after irradiation subject to the arbitrary effective order of radical recombination. It is shown that in the range of doses and dose rates under study radiation-induced scission predominates during polymer irradiation but in a certain period of time after irradiation scission changes to cross-linking. Characteristics of the kinetic curves obtained essentially depend on the dose

  10. Influence of formulation parameters on the texturing and and the structural evolution of geo-polymers

    International Nuclear Information System (INIS)

    Steins, Prune

    2014-01-01

    In the context of conditioning of nuclear waste, geo-polymers represent a potential alternative to conventional hydraulic binders. Currently, it is recognized that the formation of geo-polymer proceeds according to a mechanism of dissolution - restructuring - polymerization resulting in a solid material. Despite the availability of many studies to understand these mechanisms, the precise relationship between the chemical nature of the activating solution, the geo-polymerization process and the final microstructure should be determined from the point of view of the texturing and the structural evolution of the material. In this work, several parameters were studied: the nature of the alkali activator, the silica concentration and the addition of an aluminum source. It appears that the chemical environment of the silicate or aluminosilicate precursors is controlled by the activating solution composition. During the consolidation of the geo-polymer network, these precursors play an important role on the dissolution rate of meta kaolin, the size, the rearrangement and the aggregation of aluminosilicate oligomers involved in the porous solid network formation. Subsequently, some characteristics of the porous network which are controlled by the size and the rearrangement of oligomers vary slightly over time. The refinement of the porosity associated to first, a densification of the solid network, and secondly, a partial closure of the porosity at the nanometer scale leads to an increase in the pore size and a decrease of the pore volume. (author) [fr

  11. Evolution of radiocaesium contamination in mushrooms and influence of treatment after collection

    International Nuclear Information System (INIS)

    Daillant, O.; Boilley, D.; Josset, M.; Hettwig, B.; Fischer, H.W.

    2013-01-01

    In literature quite a lot of data is available on uptake of radioactive caesium in mushrooms. There is less available on the evolution of concentration in fruitbodies after several years and on 'outbound' transfer of radiocaesium from fruitbodies to their direct environment, i.e. dilution according to cooking techniques. The recent event at Fukushima has put the question of radionuclides in food, and the following exposure of consumers, high on the agenda. The purpose of this paper is twofold: (1) in order to investigate the variation in time of caesium uptake by fungi, analyses of the same species having grown on the same spot at different intervals during the last 25 years have been performed and (2) in terms of radiation protection the most important thing is the activity taken in by the consumer and not the contamination of raw products. Preparation can have a great impact on activity concentration. Various species of mushrooms frequently eaten have been sampled in Europe and contaminated areas in Japan. Different preparation techniques that can break the walls of the hyphae (drying, deepfreezing etc.) have been applied as well as different treatments: boiling or macerating in water with salt, in acid and basic media. The pH of different media was adjusted and measured. The samples and the medium were analysed separately in gamma spectrometry. (author)

  12. THE INFLUENCE OF SLOW THAWING ON EVOLUTION OF SOME BIOCHEMICAL COMPOUNDS IN FROZEN FISHES

    Directory of Open Access Journals (Sweden)

    Marcel AVRAMIUC

    2017-06-01

    Full Text Available The aim of this work was to study the evolution of pH, amino nitrogen and nitrogen from aminoacids in four fish species, during 48 hours of slow thawing, in order to assess the fish spoilage speed in these keeping conditions. The biological material was represented by frozen fishes (carp, catfish, mackerel and hake which were subjected to slow thawing at room temperature (+20..+22°C, by analysing, at certain time intervals, pH, amino nitrogen - AN (mg %, and nitrogen from aminoacids - NAA (g %. The pH was determined with a digital pH-meter type Hanna, and the nitrogen from aminoacids according to Sörensen method. The amino nitrogen was determined by the difference between the nitrogen content of volatile bases and the nitrogen content of the ammonia and primary amines. As compared to frozen samples, both pH and the amino nitrogen values of all fish samples showed constant and significant increases up to the end of the analyzed period, while the nitrogen from aminoacids only in the first 30 hours of thawing. The amino nitrogen and the nitrogen from amino acids values have indicated the highest spoilage speed in catfish and hake, and the least speed in mackerel.

  13. Policy Influence on Consumers’ Evolution into Prosumers—Empirical Findings from an Exploratory Survey in Europe

    Directory of Open Access Journals (Sweden)

    Kirsi Kotilainen

    2018-01-01

    Full Text Available The energy sector is in transition to a flexible and sustainable energy system based on renewable energy sources. This complex transition is affecting multiple levels in the sociotechnical system. One driver of the transition is climate change that enforces the policy push from the macro level to change the way energy is produced, delivered, and used. As part of the energy system evolution, the role of the end user in the energy sector is undergoing profound changes, and consumers are increasingly being empowered to participate actively in the production and use of energy. This article investigates how policies might affect consumers’ interests in becoming prosumers of energy. We explore consumers’ attitudes toward using renewable energy technologies (RET by means of an empirical consumer survey that was conducted in five European countries. The partial least squares structural equation modeling (PLS-SEM method was utilized to analyze the survey results. Our findings suggest that both economic and non-economic policies affect consumer attitudes toward using renewable energy technologies. We conclude that policies have different effects on consumers and prosumers, who have already made the decision to adopt renewable energy solutions. Based on the findings, we propose a set of policy and managerial implications.

  14. Fishing for space: fine-scale multi-sector maritime activities influence fisher location choice.

    Directory of Open Access Journals (Sweden)

    Alex N Tidd

    Full Text Available The European Union and other states are moving towards Ecosystem Based Fisheries Management to balance food production and security with wider ecosystem concerns. Fishing is only one of several sectors operating within the ocean environment, competing for renewable and non-renewable resources that overlap in a limited space. Other sectors include marine mining, energy generation, recreation, transport and conservation. Trade-offs of these competing sectors are already part of the process but attempts to detail how the seas are being utilised have been primarily based on compilations of data on human activity at large spatial scales. Advances including satellite and shipping automatic tracking enable investigation of factors influencing fishers' choice of fishing grounds at spatial scales relevant to decision-making, including the presence or avoidance of activities by other sectors. We analyse the determinants of English and Welsh scallop-dredging fleet behaviour, including competing sectors, operating in the eastern English Channel. Results indicate aggregate mining activity, maritime traffic, increased fishing costs, and the English inshore 6 and French 12 nautical mile limits negatively impact fishers' likelihood of fishing in otherwise suitable areas. Past success, net-benefits and fishing within the 12 NM predispose fishers to use areas. Systematic conservation planning has yet to be widely applied in marine systems, and the dynamics of spatial overlap of fishing with other activities have not been studied at scales relevant to fisher decision-making. This study demonstrates fisher decision-making is indeed affected by the real-time presence of other sectors in an area, and therefore trade-offs which need to be accounted for in marine planning. As marine resource extraction demands intensify, governments will need to take a more proactive approach to resolving these trade-offs, and studies such as this will be required as the evidential

  15. Fishing for space: fine-scale multi-sector maritime activities influence fisher location choice.

    Science.gov (United States)

    Tidd, Alex N; Vermard, Youen; Marchal, Paul; Pinnegar, John; Blanchard, Julia L; Milner-Gulland, E J

    2015-01-01

    The European Union and other states are moving towards Ecosystem Based Fisheries Management to balance food production and security with wider ecosystem concerns. Fishing is only one of several sectors operating within the ocean environment, competing for renewable and non-renewable resources that overlap in a limited space. Other sectors include marine mining, energy generation, recreation, transport and conservation. Trade-offs of these competing sectors are already part of the process but attempts to detail how the seas are being utilised have been primarily based on compilations of data on human activity at large spatial scales. Advances including satellite and shipping automatic tracking enable investigation of factors influencing fishers' choice of fishing grounds at spatial scales relevant to decision-making, including the presence or avoidance of activities by other sectors. We analyse the determinants of English and Welsh scallop-dredging fleet behaviour, including competing sectors, operating in the eastern English Channel. Results indicate aggregate mining activity, maritime traffic, increased fishing costs, and the English inshore 6 and French 12 nautical mile limits negatively impact fishers' likelihood of fishing in otherwise suitable areas. Past success, net-benefits and fishing within the 12 NM predispose fishers to use areas. Systematic conservation planning has yet to be widely applied in marine systems, and the dynamics of spatial overlap of fishing with other activities have not been studied at scales relevant to fisher decision-making. This study demonstrates fisher decision-making is indeed affected by the real-time presence of other sectors in an area, and therefore trade-offs which need to be accounted for in marine planning. As marine resource extraction demands intensify, governments will need to take a more proactive approach to resolving these trade-offs, and studies such as this will be required as the evidential foundation for future

  16. Influence of the input database in detecting fire space-time clusters

    Science.gov (United States)

    Pereira, Mário; Costa, Ricardo; Tonini, Marj; Vega Orozco, Carmen; Parente, Joana

    2015-04-01

    Fire incidence variability is influenced by local environmental variables such as topography, land use, vegetation and weather conditions. These induce a cluster pattern of the fire events distribution. The space-time permutation scan statistics (STPSS) method developed by Kulldorff et al. (2005) and implemented in the SaTScanTM software (http://www.satscan.org/) proves to be able to detect space-time clusters in many different fields, even when using incomplete and/or inaccurate input data. Nevertheless, the dependence of the STPSS method on the different characteristics of different datasets describing the same environmental phenomenon has not been studied yet. In this sense, the objective of this study is to assess the robustness of the STPSS for detecting real clusters using different input datasets and to justify the obtained results. This study takes advantage of the existence of two very different official fire datasets currently available for Portugal, both provided by the Institute for the Conservation of Nature and Forests. The first one is the aggregated Portuguese Rural Fire Database PRFD (Pereira et al., 2011), which is based on ground measurements and provides detailed information about the ignition and extinction date/time and the area burnt by each fire in forest, scrubs and agricultural areas. However, in the PRFD, the fire location of each fire is indicated by the name of smallest administrative unit (the parish) where the ignition occurred. Consequently, since the application of the STPSS requires the geographic coordinates of the events, the centroid of the parishes was considered. The second fire dataset is the national mapping burnt areas (NMBA), which is based on satellite measurements and delivered in shape file format. The NMBA provides a detailed spatial information (shape and size of each fire) but the temporal information is restricted to the year of occurrence. Besides these differences, the two datasets cover different periods, they

  17. The finite element method scheme for a solution of an evolution variational inequality with a nonlocal space operator

    Science.gov (United States)

    Glazyrina, O. V.; Pavlova, M. F.

    2016-11-01

    We consider the parabolic inequality with monotone with respect to a gradient space operator, which is depended on integral with respect to space variables solution characteristic. We construct a two-layer differential scheme for this problem with use of penalty method, semidiscretization with respect to time variable method and the finite element method (FEM) with respect to space variables. We proved a convergence of constructed mothod.

  18. Influence of Auroral Streamers on Rapid Evolution of Ionospheric SAPS Flows

    Science.gov (United States)

    Gallardo-Lacourt, Bea; Nishimura, Y.; Lyons, L. R.; Mishin, E. V.; Ruohoniemi, J. M.; Donovan, E. F.; Angelopoulos, V.; Nishitani, N.

    2017-12-01

    Subauroral polarization streams (SAPS) often show large, rapid enhancements above their slowly varying component. We present simultaneous observations from ground-based all-sky imagers and flows from the Super Dual Auroral Radar Network radars to investigate the relationship between auroral phenomena and flow enhancement. We first identified auroral streamers approaching the equatorward boundary of the auroral oval to examine how often the subauroral flow increased. We also performed the reverse query starting with subauroral flow enhancements and then evaluated the auroral conditions. In the forward study, 98% of the streamers approaching the equatorward boundary were associated with SAPS flow enhancements reaching 700 m/s and typically hundreds of m/s above background speeds. The reverse study reveals that flow enhancements associated with streamers (60%) and enhanced larger-scale convection (37%) contribute to SAPS flow enhancements. The strong correlation of auroral streamers with rapid evolution (approximately minutes) of SAPS flows suggests that transient fast earthward plasma sheet flows can often lead to westward SAPS flow enhancements in the subauroral region and that such enhancements are far more common than only during substorms because of the much more frequent occurrences of streamers under various geomagnetic conditions. We also found a strong correlation between flow duration and streamer duration and a weak correlation between SAPS flow velocity and streamer intensity. This result suggests that intense flow bursts in the plasma sheet (which correlate with intense streamers) are associated with intense SAPS ionospheric flows perhaps by enhancing the ring current pressure and localized pressure gradients when they are able to penetrate close enough to Earth.

  19. Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

    International Nuclear Information System (INIS)

    Pang Xuexia; Deng Zechao; Jia Pengying; Liang Weihua; Li Xia

    2012-01-01

    A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km). The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10 10 ∼ 10 14 cm −3 , the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O 2 − , O 4 − , CO 4 − and CO 3 − are the dominant negative species when the initial electron density n e0 ≤ 10 13 cm −3 , and only electrons and CO 3 − are left when n e0 ≥ 10 15 cm −3 · N + 2 , N + 4 and O + 2 are dominant in the positive charges for any ionization degree. Other positive species, such as O + 4 , N + 3 , NO + , NO + 2 , Ar + 2 and H 3 O + ·H 2 O, are dominant only for a certain ionization degree and in a certain period. (low temperature plasma)

  20. T2 image contrast evaluation using three dimension sampling perfection with application optimized contrasts using different flip angle evolution (3D-SPACE)

    International Nuclear Information System (INIS)

    Yamazaki, Ryo; Hiura, Yukikazu; Tsuji, Akio; Nishiki, Shigeo; Uchikoshi, Masato

    2011-01-01

    Sampling perfection with application optimized contrasts using different flip angle evolution (3D-SPACE) sequence enables one to decrease specific absorption rate (SAR) by using variable flip angle refocusing pulse. Therefore, it is expected that the contrast obtained with 3D-SPACE sequences is different from that of spin echo (SE) images and turbo spin echo (TSE) images. The purpose of this study was to evaluate the characteristics of the signal intensity and central nervous system (CNS) image contrast in T 2 weighted 3D-SPACE. Using 3 different sequences (SE, 3D-TSE and 3D-SPACE) with repetition time (TR)/ echo time (TE)=3500/70, 90 and 115 ms, we obtained T 2 weighted magnetic resonance (MR) images of inhouse phantom and five healthy volunteers' brain. Signal intensity of the phantom which contains various T 1 and T 2 value was evaluated. Tissue contrasts of white/gray matter, cerebrospinal fluid (CSF)/subcutaneous fat and gray matter/subcutaneous fat were evaluated for a clinical image study. The phantom study showed that signal intensity in 3D-SPACE significantly decreased under a T 1 value of 250 ms. It was markedly decreased in comparison to other sequences, as effective echo time (TE) was extended. White/gray matter contrast of 3D-SPACE was the highest in all sequences. On the other hand, CSF/fat and gray matter/fat contrast of 3D-SPACE was higher than TSE but lower than SE. CNS image contrasts of 3D-SPACE were comparable to that of SE. Signal intensity had decreased in the range where T 1 and T 2 values were extremely short. (author)

  1. Tidal influences on a future evolution of the Filchner-Ronne Ice Shelf cavity in the Weddell Sea, Antarctica

    Science.gov (United States)

    Mueller, Rachael D.; Hattermann, Tore; Howard, Susan L.; Padman, Laurie

    2018-02-01

    Recent modeling studies of ocean circulation in the southern Weddell Sea, Antarctica, project an increase over this century of ocean heat into the cavity beneath Filchner-Ronne Ice Shelf (FRIS). This increase in ocean heat would lead to more basal melting and a modification of the FRIS ice draft. The corresponding change in cavity shape will affect advective pathways and the spatial distribution of tidal currents, which play important roles in basal melting under FRIS. These feedbacks between heat flux, basal melting, and tides will affect the evolution of FRIS under the influence of a changing climate. We explore these feedbacks with a three-dimensional ocean model of the southern Weddell Sea that is forced by thermodynamic exchange beneath the ice shelf and tides along the open boundaries. Our results show regionally dependent feedbacks that, in some areas, substantially modify the melt rates near the grounding lines of buttressed ice streams that flow into FRIS. These feedbacks are introduced by variations in meltwater production as well as the circulation of this meltwater within the FRIS cavity; they are influenced locally by sensitivity of tidal currents to water column thickness (wct) and non-locally by changes in circulation pathways that transport an integrated history of mixing and meltwater entrainment along flow paths. Our results highlight the importance of including explicit tidal forcing in models of future mass loss from FRIS and from the adjacent grounded ice sheet as individual ice-stream grounding zones experience different responses to warming of the ocean inflow.

  2. Influence of intra-row spacing and mulching on weed growth and ...

    African Journals Online (AJOL)

    hope&shola

    2006-02-02

    Feb 2, 2006 ... response of weed growth and bulb yield of garlic to intra-row spacing and mulching. ... advantageous effects on the growth and yield of this crop. ... Portulaca oleracea L x xx .... 50DAP. 60DAP. Spacing (cm). 20 x 10. 2.60b. 4.69. 6.34b. 12.54b. 2.68. 3.90 .... Effect of plant spacing and nitrogen fertilization on.

  3. Neutral Evolution in a Biological Population as Diffusion in Phenotype Space: Reproduction with Local Mutation but without Selection

    Science.gov (United States)

    Lawson, Daniel John; Jensen, Henrik Jeldtoft

    2007-03-01

    The process of “evolutionary diffusion,” i.e., reproduction with local mutation but without selection in a biological population, resembles standard diffusion in many ways. However, evolutionary diffusion allows the formation of localized peaks that undergo drift, even in the infinite population limit. We relate a microscopic evolution model to a stochastic model which we solve fully. This allows us to understand the large population limit, relates evolution to diffusion, and shows that independent local mutations act as a diffusion of interacting particles taking larger steps.

  4. The influence of diet on the evolution of symptoms presented in fibromyalgia patients

    Directory of Open Access Journals (Sweden)

    José Eduardo Martinez

    2015-06-01

    Full Text Available This research seeks to relate fibromyalgia and nutritional factors. Objective: to determine the influence of the food habits on the intensity of the symptoms of fibromyalgia patients. Methods: we interviewed 40 female patients, aged 15 to 59, in the clinic of the Hospital pain set of Sorocaba (CHS through about the fibromyalgia clinical picture and their eating habits. Results: the mean duration of symptoms of fibromyalgia among the interviewed patients was 6.75 years. The average impact of fibromyalgia on the quality of life was about 64 measured by the Fibromyalgia Impact Questionnaire. The only food that was related to symptom improvement by the patients was the banana (17.5%. The majority of respondents did not noticed relationship between such foods and modification of disease symptoms. Conclusion: there was not observed association between food intenak and fibromyalgia symptom severity.

  5. THE INFLUENCE OF BIOTIC FACTORS ON THE AESTHETIC, FUNCTIONAL AND ECONOMIC ISSUES OF GREEN SPACES IN PITESTI

    Directory of Open Access Journals (Sweden)

    Mihaela Ileana Oprea

    2017-07-01

    Full Text Available This case study aims to highlight the influence of some direct biotic factors (dogs, man, birds on the integrity of green spaces in the Pitesti city centre during three consecutive years: 2014, 2015 and 2016. Observations on the appearance of the affected areas were carried out, as well as determinations on: the number of destroyed/stolen floral plants (units and the degraded/destroyed area of green space (sqm, by the biotic factors studied. The total percentage of losses was determined and the costs generated by the restoration of affected areas were assessed.

  6. Fluid overload correction and cardiac history influence brain natriuretic peptide evolution in incident haemodialysis patients.

    Science.gov (United States)

    Chazot, Charles; Vo-Van, Cyril; Zaoui, Eric; Vanel, Thierry; Hurot, Jean Marc; Lorriaux, Christie; Mayor, Brice; Deleaval, Patrick; Jean, Guillaume

    2011-08-01

    Brain natriuretic peptide (BNP) is a cardiac peptide secreted by ventricle myocardial cells under stretch constraint. Increased BNP has been shown associated with increased mortality in end-stage renal disease patients. In patients starting haemodialysis (HD), both fluid overload and cardiac history are frequently present and may be responsible for a high BNP plasma level. We report in this study the evolution of BNP levels in incident HD patients, its relationship with fluid removal and cardiac history as well as its prognostic value. Forty-six patients (female/male: 21/25; 68.6 ± 14.5 years old) surviving at least 6 months after HD treatment onset were retrospectively analysed. Plasma BNP (Chemoluminescent Microparticule ImmunoAssay on i8200 Architect Abbott, Paris, France; normal value < 100 pg/mL) was assessed at HD start and during the second quarter of HD treatment (Q2). At dialysis start, the plasma BNP level was 1041 ± 1178 pg/mL (range: 14-4181 pg/mL). It was correlated with age (P = 0.0017) and was significantly higher in males (P = 0.0017) and in patients with cardiac disease history (P = 0.001). The plasma BNP level at baseline was not related to the mortality risk. At Q2, predialysis systolic blood pressure (BP) decreased from 140.5 ± 24.5 to 129.4 ± 20.6 mmHg (P = 0.0001) and the postdialysis body weight by 7.6 ± 8.4% (P < 0.0001). The BNP level decreased to 631 ± 707 pg/mL (P = 0.01) at Q2. Its variation was significantly correlated with systolic BP decrease (P = 0.006). A high BNP level was found associated with an increased risk of mortality. Hence, plasma BNP levels decreased during the first months of HD treatment during the dry weight quest. Whereas initial BNP values were not associated with increased mortality risk, the BNP level at Q2 was independently predictive of mortality. Hence, BNP is a useful tool to follow patient dehydration after dialysis start. Initial fluid overload may act as a confounding factor for its value as a

  7. Influence of irradiation conditions on plasma evolution in laser-surface interaction

    Science.gov (United States)

    Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

    1993-09-01

    The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

  8. CFD modeling of space-time evolution of fast pyrolysis products in a bench-scale fluidized-bed reactor

    International Nuclear Information System (INIS)

    Boateng, A.A.; Mtui, P.L.

    2012-01-01

    A model for the evolution of pyrolysis products in a fluidized bed has been developed. In this study the unsteady constitutive transport equations for inert gas flow and decomposition kinetics were modeled using the commercial computational fluid dynamics (CFD) software FLUENT-12. The Eulerarian-Eulerian multiphase model system described herein is a fluidized bed of sand externally heated to a predetermined temperature prior to introduction of agricultural biomass. We predict the spontaneous emergence of pyrolysis vapors, char and non-condensable (permanent) gases and confirm the observation that the kinetics are fast and that bio-oil vapor evolution is accomplished in a few seconds, and occupying two-thirds of the spatial volume of the reactor as widely reported in the open literature. The model could be advantageous in the virtual design of fast pyrolysis reactors and their optimization to meet economic scales required for distributed or satellite units. - Highlights: ► We model the evolution of pyrolysis products in a fluidized bed via CFD. ► We predict the spontaneous emergence of pyrolysis products. ► We confirm the experimental observation that the kinetics are fast. ► And that bio-oil vapor evolution is accomplished in a few seconds. ► The model is advantageous in the virtual design of fast pyrolysis reactors.

  9. Mission Operations Directorate - Success Legacy of the Space Shuttle Program (Overview of the Evolution and Success Stories from MOD During the Space Shuttle program)

    Science.gov (United States)

    Azbell, Jim A.

    2011-01-01

    In support of the Space Shuttle Program, as well as NASA's other human space flight programs, the Mission Operations Directorate (MOD) at the Johnson Space Center has become the world leader in human spaceflight operations. From the earliest programs - Mercury, Gemini, Apollo - through Skylab, Shuttle, ISS, and our Exploration initiatives, MOD and its predecessors have pioneered ops concepts and emphasized a history of mission leadership which has added value, maximized mission success, and built on continual improvement of the capabilities to become more efficient and effective. This paper provides specific examples that illustrate how MOD's focus on building and contributing value with diverse teams has been key to their successes both with the US space industry and the broader international community. This paper will discuss specific examples for the Plan, Train, Fly, and Facilities aspects within MOD. This paper also provides a discussion of the joint civil servant/contractor environment and the relative badge-less society within MOD. Several Shuttle mission related examples have also been included that encompass all of the aforementioned MOD elements and attributes, and are used to show significant MOD successes within the Shuttle Program. These examples include the STS-49 Intelsat recovery and repair, the (post-Columbia accident) TPS inspection process and the associated R-Bar Pitch Maneuver for ISS missions, and the STS-400 rescue mission preparation efforts for the Hubble Space Telescope repair mission. Since their beginning, MOD has consistently demonstrated their ability to evolve and respond to an ever changing environment, effectively prepare for the expected and successfully respond to the unexpected, and develop leaders, expertise, and a culture that has led to mission and Program success.

  10. Influence of Inter and Intra-rows Spacing on Yield and Yield ...

    African Journals Online (AJOL)

    Abyssinia

    yield and yield components of fresh market(Bishola) and processing (Cochoro) tomato cultivars. ... row spacing had a significant effect on plan canopy width, above ground dry biomass, ... Poor varietal performance and management practices that includeinter and intra-row spacing ..... of assimilate export from the leaves.

  11. Spacing and shrub competition influence 20-year development of planted ponderosa pine

    Science.gov (United States)

    William W. Oliver

    1990-01-01

    Growth and stand development of ponderosa pine (Pinus ponderosa) were monitored for 20 years after planting at five different square spacings (6, 9, 12, 15, and 18 ft) in the presence or absence of competing shrubs on the westside Sierra Nevada. Mean tree size was positively correlated and stand values negatively correlated with spacing in the...

  12. Initiating and maintaining recreational walking: a longitudinal study on the influence of neighborhood green space.

    Science.gov (United States)

    Sugiyama, Takemi; Giles-Corti, Billie; Summers, Jacqui; du Toit, Lorinne; Leslie, Eva; Owen, Neville

    2013-09-01

    This study examined prospective relationships of green space attributes with adults initiating or maintaining recreational walking. Postal surveys were completed by 1036 adults living in Adelaide, Australia, at baseline (two time points in 2003-04) and follow-up (2007-08). Initiating or maintaining recreational walking was determined using self-reported walking frequency. Green space attributes examined were perceived presence, quality, proximity, and the objectively measured area (total and largest) and number of green spaces within a 1.6 km buffer drawn from the center of each study neighborhood. Multilevel regression analyses examined the odds of initiating or maintaining walking separately for each green space attribute. At baseline, participants were categorized into non-regular (n = 395), regular (n = 286), and irregular walkers (n = 313). Among non-regular walkers, 30% had initiated walking, while 70% of regular walkers had maintained walking at follow-up. No green space attributes were associated with initiating walking. However, positive perceptions of the presence of and proximity to green spaces and the total and largest areas of green space were significantly associated with a higher likelihood of walking maintenance over four years. Neighborhood green spaces may not assist adults to initiate walking, but their presence and proximity may facilitate them to maintain recreational walking over time. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Theoretical study of the influence of intense femtosecond laser field on the evolution of the wave packet and the population of NaRb molecule

    International Nuclear Information System (INIS)

    Ning, Ma; Mei-Shan, Wang; Chuan-Lu, Yang; Xiao-Guang, Ma; De-Hua, Wang

    2010-01-01

    Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the population of ground and double-minimum electronic states of the NaRb molecule. For the different laser wavelengths, the evolution of the wave packet of 6 1 σ + state with time and internuclear distance is different, and the different laser intensity brings different influences on the population of the electronic states of the NaRb molecule. One can control the evolutions of wave packet and the population in each state by varying the laser parameters appropriately, which will be a benefit for the light manipulation of atomic and molecular processes. (atomic and molecular physics)

  14. Rift architecture and evolution: The Sirt Basin, Libya: The influence of basement fabrics and oblique tectonics

    Science.gov (United States)

    Abdunaser, K. M.; McCaffrey, K. J. W.

    2014-12-01

    zones and adjoining highs. Late Eocene rocks exposed in the western part of the basin exhibit a complex network of branching segmented normal and strike-slip faults, generally with a NNW-SSE structural orientations. Many surface structural features have been interpreted from satellite images which confirm sinistral strike-slip kinematics. Relay ramp structures, numerous elongate asymmetric synclines associated with shallow west limbs and steeper dipping east limbs are developed in the hangingwalls adjacent to west downthrowing normal faults. These structural patterns reflect Cretaceous/Tertiary extensional tectonics with additional control by underlying pre-existing Pan-African basement fabrics and ENE-WSW trending Hercynian structures. We relate the Sirt Basin rift development as exemplified in our study area to the break-up of Gondwana represented by the structural evolution of the West-Central African rift system, and the South and Central Atlantic, the Tethys and the Indian Oceans.

  15. The Evolution of Research on Digital Education

    Science.gov (United States)

    Dillenbourg, Pierre

    2016-01-01

    How does AI&EdAIED today compare to 25 years ago? This paper addresses this evolution by identifying six trends. The trends are ongoing and will influence learning technologies going forward. First, the physicality of interactions and the physical space of the learner became genuine components of digital education. The frontier between the…

  16. Influence of the oxygen partial pressure on the phase evolution during Bi-2212 wire melt processing

    CERN Document Server

    Scheuerlein, C.; Rikel, M.O.; Kadar, J.; Doerrer, C.; Di Michiel, M.; Ballarino, A.; Bottura, L.; Jiang, J.; Kametani, F.; Hellstrom, E.E.; Larbalestier, D.C.

    2016-01-01

    We have studied the influence of the oxygen partial pressure pO2 up to 5.5 bar on the phase changes that occur during melt processing of a state-of-the-art Bi-2212 multifilamentary wire. Phase changes have been monitored in situ by high energy synchrotron X-ray diffraction (XRD). We found that the stability of Bi-2212 phase is reduced with increasing pO2. For pO2>1 bar a significant amount of Bi-2212 phase decomposes upon heating in the range 400 to 650 °C. The extent of decomposition strongly increases with increasing pO2, and at pO2=5.5 bar Bi-2212 decomposes completely in the solid state. Textured Bi-2212 can be formed during solidification when pO2 is reduced to 0.45 bar when the precursor is molten. Since the formation of current limiting second phases is very sensitive to pO2 when it exceeds 1 bar, we recommend to reduce the oxygen partial pressure below the commonly used pO2=1 bar, in order to increase the pO2 margins and to make the overpressure process more robust.

  17. Influence of chemical and structural evolution of dissolved organic matter on electron transfer capacity during composting

    International Nuclear Information System (INIS)

    He, Xiao-Song; Xi, Bei-Dou; Cui, Dong-Yu; Liu, Yong; Tan, Wen-Bin; Pan, Hong-Wei; Li, Dan

    2014-01-01

    Highlights: • Electron transfer capability (ETC) of compost-derived DOM was investigated. • Composting treatment increased the ETC of DOM from municipal solid wastes. • The ETC increase related to humic matter, and molecule weight, and N and S content. - Abstract: Dissolved organic matter (DOM) can mediate electron transfer and change chemical speciation of heavy metals. In this study, the electron transfer capability (ETC) of compost-derived DOM was investigated through electrochemical approaches, and the factors influencing the ETC were studied using spectral and elemental analysis. The results showed that the electron accepting capacity (EAC) and electron donating capacity (EDC) of compost-derived DOM were 3.29–40.14 μmol e− (g C) −1 and 57.1– 346.07 μmol e− (g C) −1 , respectively. Composting treatment increased the fulvic- and humic-like substance content, oxygenated aliphatic carbon content, lignin-derived aromatic carbon content, molecule weight, and N and S content of DOM, but decreased the aliphatic carbon content and the C and H content. This conversion increased the EDC and EAC of the DOM during composting

  18. Influence of chemical and structural evolution of dissolved organic matter on electron transfer capacity during composting

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiao-Song [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Innovation base of Ground Water and Environmental System Engineering, Chinese Research Academy of Environmental Science, Beijing 100012 (China); Xi, Bei-Dou, E-mail: hexs82@126.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Innovation base of Ground Water and Environmental System Engineering, Chinese Research Academy of Environmental Science, Beijing 100012 (China); Cui, Dong-Yu [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Innovation base of Ground Water and Environmental System Engineering, Chinese Research Academy of Environmental Science, Beijing 100012 (China); Liu, Yong [Guangdong Key Laboratory of Agro-Environmental Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Tan, Wen-Bin; Pan, Hong-Wei; Li, Dan [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Innovation base of Ground Water and Environmental System Engineering, Chinese Research Academy of Environmental Science, Beijing 100012 (China)

    2014-03-01

    Highlights: • Electron transfer capability (ETC) of compost-derived DOM was investigated. • Composting treatment increased the ETC of DOM from municipal solid wastes. • The ETC increase related to humic matter, and molecule weight, and N and S content. - Abstract: Dissolved organic matter (DOM) can mediate electron transfer and change chemical speciation of heavy metals. In this study, the electron transfer capability (ETC) of compost-derived DOM was investigated through electrochemical approaches, and the factors influencing the ETC were studied using spectral and elemental analysis. The results showed that the electron accepting capacity (EAC) and electron donating capacity (EDC) of compost-derived DOM were 3.29–40.14 μmol{sub e−} (g C){sup −1} and 57.1– 346.07 μmol{sub e−} (g C){sup −1}, respectively. Composting treatment increased the fulvic- and humic-like substance content, oxygenated aliphatic carbon content, lignin-derived aromatic carbon content, molecule weight, and N and S content of DOM, but decreased the aliphatic carbon content and the C and H content. This conversion increased the EDC and EAC of the DOM during composting.

  19. Cyclical evolution of nursing education and profession in Iran: religious, cultural, and political influences.

    Science.gov (United States)

    Mura, P; Mura, A

    1995-01-01

    This article was written to gain some insight into the underlying social and/or cultural forces that have, over the centuries, influenced the development of nursing education and the nursing profession in Iran, one of the most ancient civilizations of the world. As a native of Iran deeply involved in the nursing profession and in many aspects of nursing education, I decided to review my many years of experience and observations in these fields in Iran to better understand how the noble profession evolved as it did in my native country. For the years following the Islamic Revolution of 1977 to 1979, I was forced to rely on information gathered from my professional colleagues. An extensive search of the literature yielded a better understanding of the very early years. Analysis of this data seemingly produced a potpourri of such basic issues as modes of education, cultural/religious states of consciousness, and the rights of women. These are not factors generally considered germane to the development of the nursing profession and nursing education, although the latter two have proven to be crucial issues in understanding the development and current status of nursing education and the nursing profession in Iran.

  20. Influence of radiation damage evolution on lattice-location, measurements for Yb and Au in iron

    International Nuclear Information System (INIS)

    Cohen, C.; Abel, F.; Bruneaux, M.; Thome, L.; Bernas, H.; Chaumont, J.

    1978-01-01

    The influence of radiation damage on lattice-location of heavy impurities (Yb and Au) implanted in iron is studied by channeling experiments. The nature of the impurity-radiation damage interaction has been modified by annealing of room-temperature implanted samples or high temperature implantation. The value of the corrected extinction ratio epsilon measured in several crystallographic directions on room-temperature implanted Yb and Au impurities cannot be interpreted uniquely in terms of different site populations. The annealing and implantation temperature dependences of the ratio epsilon for Yb-implanted Fe are very different. Upon annealing, the value of epsilon is unchanged up to 420 0 C and then drops abruptly. In hot-implant experiments, the extinction ratio starts to fall at approximately 150 0 C when vacancies become mobile. Vacancy-assisted diffusion is suggested to cause the changes of epsilon in both experiments. The temperature dependence of epsilon for the (100) plane is found to differ from that in other directions. This planar effect suggests that Yb impurities move preferentially in the (100) plane, which is the plane of vacancy-loops in Fe. A quantitative analysis of these lattice-location results and of related hyperfne interaction results is presented in a companion paper

  1. On the representation of contextual probabilistic dynamics in the complex Hilbert space: Linear and nonlinear evolutions, Schrodinger dynamics

    International Nuclear Information System (INIS)

    Khrennikov, A.

    2005-01-01

    We constructed the representation of contextual probabilistic dynamics in the complex Hilbert space. Thus dynamics of the wave function can be considered as Hilbert space projection of realistic dynamics in a pre space. The basic condition for representing the pre space-dynamics is the law of statistical conservation of energy-conservation of probabilities. The construction of the dynamical representation is an important step in the development of contextual statistical viewpoint of quantum processes. But the contextual statistical model is essentially more general than the quantum one. Therefore in general the Hilbert space projection of the pre space dynamics can be nonlinear and even irreversible (but it is always unitary). There were found conditions of linearity and reversibility of the Hilbert space dynamical projection. We also found conditions for the conventional Schrodinger dynamics (including time-dependent Hamiltonians). We remark that in general even the Schrodinger dynamics is based just on the statistical conservation of energy; for individual systems the law of conservation of energy can be violated (at least in our theoretical model)

  2. Social and economic well-being in the conditions of the urban space: the evolution of methodological approaches in the historical urban studies

    Directory of Open Access Journals (Sweden)

    Ageev Ilya

    2016-01-01

    Full Text Available A city as a type of a human settlement is characterized by high population density, welldeveloped infrastructure, comfortable living conditions. However, a city is a source of social problems due to high population density, limited resources and conflicts between indigenous population and newcomers. The article analyzes the development of research about the city, provides an assessment of the scope of the historical urban studies in the development of solutions to contemporary problems of urban space. Methodological resource of historical urban studies allows fully exploring the city as a set of historically interconnected spaces and social processes. The analysis of the problem field of historical urban studies at various stages of its formation allowed tracing the evolution of ideas about the city as an object of scientific knowledge, to identify future prospects of research on conditions of Russian urban development, to improve the comfort of living in them.

  3. Design of cycler trajectories and analysis of solar influences on radioactive decay rates during space missions

    Science.gov (United States)

    Rogers, Blake A.

    This thesis investigates the design of interplanetary missions for the continual habitation of Mars via Earth-Mars cyclers and for the detection of variations in nuclear decay rates due to solar influences. Several cycler concepts have been proposed to provide safe and comfortable quarters for astronauts traveling between the Earth and Mars. However, no literature has appeared to show how these massive vehicles might be placed into their cycler trajectories. Trajectories are designed that use either Vinfinity leveraging or low thrust to establish cycler vehicles in their desired orbits. In the cycler trajectory cases considered, the use of Vinfinity leveraging or low thrust substantially reduces the total propellant needed to achieve the cycler orbit compared to direct orbit insertion. In the case of the classic Aldrin cycler, the propellant savings due to Vinfinity leveraging can be as large as a 24 metric ton reduction for a cycler vehicle with a dry mass of 75 metric tons, and an additional 111 metric ton reduction by instead using low thrust. The two-synodic period cyclers considered benefit less from Vinfinity leveraging, but have a smaller total propellant mass due to their lower approach velocities at Earth and Mars. It turns out that, for low-thrust establishment, the propellant required is approximately the same for each of the cycler trajectories. The Aldrin cycler has been proposed as a transportation system for human missions between Earth and Mars. However, the hyperbolic excess velocity values at the planetary encounters for these orbits are infeasibly large, especially at Mars. In a new version of the Aldrin cycler, low thrust is used in the interplanetary trajectories to reduce the encounter velocities. Reducing the encounter velocities at both planets reduces the propellant needed by the taxis (astronauts use these taxis to transfer between the planetary surfaces and the cycler vehicle) to perform hyperbolic rendezvous. While the propellant

  4. Quantum influence of topological defects in Goedel-type space-times

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Josevi [Universidade Federal de Campina Grande, Unidade Academica de Tecnologia de Alimentos, Centro de Ciencias e Tecnologia Agroalimentar, Pombal, PB (Brazil); Carvalho, M.; Alexandre, M. de [Universidade Federal de Alagoas, Instituto de Fisica, Maceio, AL (Brazil); Furtado, Claudio [Universidade Federal da Paraiba, Cidade Universitaria, Departamento de Fisica, CCEN, Joao Pessoa, PB (Brazil)

    2014-06-15

    In this contribution, some solutions of the Klein-Gordon equation in Goedel-type metrics with an embedded cosmic string are considered. The quantum dynamics of a scalar particle in three spaces whose metrics are described by different classes of Goedel solutions, with a cosmic string passing through the spaces, is found. The energy levels and eigenfunctions of the Klein-Gordon operator are obtained. We show that these eigenvalues and eigenfunctions depend on the parameter characterizing the presence of a cosmic string in the space-time. We note that the presence of topological defects breaks the degeneracy of energy levels. (orig.)

  5. Robotic influence in the conceptual design of mechanical systems in space and vice versa - A survey

    Science.gov (United States)

    Sanger, George F.

    1988-01-01

    A survey of methods using robotic devices to construct structural elements in space is presented. Two approaches to robotic construction are considered: one in which the structural elements are designed using conventional aerospace techniques which tend to constrain the function aspects of robotics and one in which the structural elements are designed from the conceptual stage with built-in robotic features. Examples are presented of structural building concepts using robotics, including the construction of the SP-100 nuclear reactor power system, a multimirror large aperture IR space telescope concept, retrieval and repair in space, and the Flight Telerobotic Servicer.

  6. Automation and robotics for the Space Station - The influence of the Advanced Technology Advisory Committee

    Science.gov (United States)

    Nunamaker, Robert R.; Willshire, Kelli F.

    1988-01-01

    The reports of a committee established by Congress to identify specific systems of the Space Station which would advance automation and robotics technologies are reviewed. The history of the committee, its relation to NASA, and the reports which it has released are discussed. The committee's reports recommend the widespread use of automation and robotics for the Space Station, a program for technology development and transfer between industries and research and development communities, and the planned use of robots to service and repair satellites and their payloads which are accessible from the Space Station.

  7. Influences on the use of urban green space - a case study in Odense, Denmark

    DEFF Research Database (Denmark)

    Schipperijn, Jasper; Stigsdotter, Ulrikka; Randrup, Thomas

    2010-01-01

    Increasing the use of urban green space has appeared on the political agenda, primarily because increased use is expected to improve the health and well-being of the urban population. Green space is contributing to restoring mental fatigue, serving as a resource for physical activity, reducing...... from a survey sent to 2500 randomly selected adult residents within the central part of the city. We tested the relative importance of different factors on the frequency of use of the nearest urban green space by using a multivariate logistic regression model. The results show that almost half...

  8. Influence of plant spacing on seed and ware tuber production of ...

    African Journals Online (AJOL)

    The highest number of seed-sized tubers (40-75 g) was obtained at high planting density, i.e. 50 cm x 25 cm and 60 cm x 25 cm. Since spacing 50 cm x 25 cm requires more planting material and also makes inter-cultivation practices more difficult, the spacing of 60 cm x 25 cm was recommended for maximizing production ...

  9. An Experimental Study on the Influence of Soundscapes on People's Behaviour in an Open Public Space

    OpenAIRE

    Aletta, F.; Lepore, F.; Kostara-Konstantinou, E.; Kang, J.; Astolfi, A.

    2016-01-01

    Several studies have investigated how environmental sounds and music can modulate people’s behaviours, particularly in marketing research. However, there are relatively few examples of research about such relationships with a focus on the management of urban public spaces. The current study investigated an open public space used mainly as a pedestrian crossing to analyse the relationship between the audio stimuli and peoples’ behaviours. An experiment relying on covert behavioural observation...

  10. The influence of anxiety and personality factors on comfort and reachability space: a correlational study.

    Science.gov (United States)

    Iachini, Tina; Ruggiero, Gennaro; Ruotolo, Francesco; Schiano di Cola, Armando; Senese, Vincenzo Paolo

    2015-09-01

    Although the effects of several personality factors on interpersonal space (i.e. social space within personal comfort area) are well documented, it is not clear whether they also extend to peripersonal space (i.e. reaching space). Indeed, no study has directly compared these spaces in relation to personality and anxiety factors even though such a comparison would help to clarify to what extent they share similar mechanisms and characteristics. The aim of the present paper was to investigate whether personality dimensions and anxiety levels are associated with reaching and comfort distances. Seventy university students (35 females) were administered the Big Five Questionnaire and the State-Trait Anxiety Inventory; afterwards, they had to provide reachability- and comfort-distance judgments towards human confederates while standing still (passive) or walking towards them (active). The correlation analyses showed that both spaces were positively related to anxiety and negatively correlated with the Dynamism in the active condition. Moreover, in the passive condition higher Emotional Stability was related to shorter comfort distance, while higher cognitive Openness was associated with shorter reachability distance. The implications of these results are discussed.

  11. Evolution of farm and manure management and their influence on ammonia emissions from agriculture in Switzerland between 1990 and 2010

    Science.gov (United States)

    Kupper, Thomas; Bonjour, Cyrill; Menzi, Harald

    2015-02-01

    The evolution of farm and manure management and their influence on ammonia (NH3) emissions from agriculture in Switzerland between 1990 and 2010 was modeled. In 2010, total agricultural NH3 emissions were 48,290 t N. Livestock contributed 90% (43,480 t N), with the remaining 10% (4760 t N) coming from arable and fodder crops. The emission stages of grazing, housing/exercise yard, manure storage and application produced 3%, 34%, 17% and 46%, respectively, of livestock emissions. Cattle, pigs, poultry, small ruminants, horses and other equids accounted for 78%, 15%, 3%, 2% and 2%, respectively, of the emissions from livestock and manure management. Compared to 1990, total NH3 emissions from agriculture and from livestock decreased by 16% and 14%, respectively. This was mainly due to declining livestock numbers, since the emissions per animal became bigger for most livestock categories between 1990 and 2010. The production volume for milk and meat remained constant or increased slightly. Other factors contributing to the emission mitigation were increased grazing for cattle, the growing importance of low-emission slurry application techniques and a significant reduction in the use of mineral fertilizer. However, production parameters enhancing emissions such as animal-friendly housing systems providing more surface area per animal and total volume of slurry stores increased during this time period. That such developments may counteract emission mitigation illustrates the challenge for regulators to balance the various aims in the striving toward sustainable livestock production. A sensitivity analysis identified parameters related to the excretion of total ammoniacal nitrogen from dairy cows and slurry application as being the most sensitive technical parameters influencing emissions. Further improvements to emission models should therefore focus on these parameters.

  12. Evolution of Subaerial Coastal Fluvial Delta Island Topography into Multiple Stable States Under Influence of Vegetation and Stochastic Hydrology

    Science.gov (United States)

    Moffett, K. B.; Smith, B. C.; O'Connor, M.; Mohrig, D. C.

    2014-12-01

    Coastal fluvial delta morphodynamics are prominently controlled by external fluvial sediment and water supplies; however, internal sediment-water-vegetation feedbacks are now being proposed as potentially equally significant in organizing and maintaining the progradation and aggradation of such systems. The time scales of fluvial and climate influences on these feedbacks, and of their responses, are also open questions. Historical remote sensing study of the Wax Lake Delta model system (Louisiana, USA) revealed trends in the evolution of the subaerial island surfaces from a non-systematic arrangement of elevations to a discrete set of levees and intra-island platforms with distinct vegetation types, designated as high marsh, low marsh, and mudflat habitat. We propose that this elevation zonation is consistent with multiple stable state theory, e.g. as applied to tidal salt marsh systems but not previously to deltas. According to zonally-distributed sediment core analyses, differentiation of island elevations was not due to organic matter accumulation as in salt marshes, but rather by differential mineral sediment accumulation with some organic contributions. Mineral sediment accumulation rates suggested that elevation growth was accelerating or holding steady over time, at least to date in this young delta, in contrast to theory suggesting rates should slow as elevation increases above mean water level. Hydrological analysis of island flooding suggested a prominent role of stochastic local storm events in raising island water levels and supplying mineral sediment to the subaerial island surfaces at short time scales; over longer time scales, the relative influences of local storms and inland/regional floods on the coupled sediment-water-vegetation system of the subaerial delta island surfaces remain the subject of ongoing study. These results help provide an empirical foundation for the next generation of coupled sediment-water-vegetation modeling and theory.

  13. Influence of wind speed on free space optical communication performance for Gaussian beam propagation through non Kolmogorov strong turbulence

    International Nuclear Information System (INIS)

    Deng Peng; Yuan Xiuhua; Zeng Yanan; Zhao Ming; Luo Hanjun

    2011-01-01

    In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, affecting link performance. Most theoretical treatments have been described by Kolmogorov's power spectral density model through weak turbulence with constant wind speed. However, several experiments showed that Kolmogorov theory is sometimes incomplete to describe atmospheric turbulence properly, especially through the strong turbulence with variable wind speed, which is known to contribute significantly to the turbulence in the atmosphere. We present an optical turbulence model that incorporates into variable wind speed instead of constant value, a non-Kolmogorov power spectrum that uses a generalized exponent instead of constant standard exponent value 11/3, and a generalized amplitude factor instead of constant value 0.033. The free space optical communication performance for a Gaussian beam wave of scintillation index, mean signal-to-noise ratio , and mean bit error rate , have been derived by extended Rytov theory in non-Kolmogorov strong turbulence. And then the influence of wind speed variations on free space optical communication performance has been analyzed under different atmospheric turbulence intensities. The results suggest that the effects of wind speed variation through non-Kolmogorov turbulence on communication performance are more severe in many situations and need to be taken into account in free space optical communication. It is anticipated that this work is helpful to the investigations of free space optical communication performance considering wind speed under severe weather condition in the strong atmospheric turbulence.

  14. The spatial-temporal evolution of aerosol optical depth and the analysis of influence factors in Bohai Rim

    International Nuclear Information System (INIS)

    Hou, Chunliang; Jiang, Hong; Wang, Xiaoyan; Pei, Huan

    2014-01-01

    Aerosol Optical Depth (AOD) is an important parameter of aerosol optical properties and it is an important physical parameter quantity to understanding the atmospheric environment. Bohai Rim is one of the three major urban agglomeration regions with rapidly developing economy in China. The study of AOD over this region is important to understand the environment and climate in Bohai Rim. Firstly, aerosol product data from 2000 to 2010, published by NASA, were used to analyze the temporal-spatial evolution of AOD in Bohai Rim with precision evaluation. The results showed that the spatial distribution of AOD had an obvious regional characteristic. The spatial distribution characterized that a much high value existed at urban areas and plain areas. On the contrary, the low value data existed in some mountainous regions which had higher percentages of forest coverage. The AOD values fluctuated somewhat each year in the region, from the minimum annual mean in 2003 to the maximum in 2009. Generally, the highest AOD value was in summer, followed by spring, autumn and winter. In terms of monthly variation, the value of AOD reached its peak in June and the lowest value was in December. This study analyzed the relation between AOD and some influence factors such as land use types, elevation, and distribution of urban agglomeration and so on. These results provide an important basic dataset for climate and environmental research

  15. Evolution of Multispectral Aerosol Absorption Properties in a Biogenically-Influenced Urban Environment during the CARES Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Gyawali, Madhu; Arnott, W.; Zaveri, Rahul; Song, Chen; Flowers, Bradley; Dubey, Manvendra; Setyan, Ari; Zhang, Qi; China, Swarup; Mazzoleni, Claudio; Gorkowski, Kyle; Subramanian, R.; Moosmüller, Hans

    2017-11-01

    We present the evolution of multispectral optical properties as urban aerosols aged and interacted with biogenic emissions resulting in stronger short wavelength absorption and formation of moderately brown secondary organic aerosols. Ground-based aerosol measurements were made during June 2010 within the Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area. Data on black carbon and non-refractory aerosol mass and composition were collected at both sites. In addition, photoacoustic (PA) instruments with integrating nephelometers were used to measure spectral absorption and scattering coefficients for wavelengths ranging from 355 to 870 nm. The daytime absorption Ångström exponent (AAE) indicated a modest wavelength-dependent enhancement of absorption at both sites throughout the study. From the 22nd to the 28th of June, secondary organic aerosol mass increased significantly at both sites due to increased biogenic emissions coupled with intense photochemical activity and air mass recirculation in the area. During this period, the median BC mass-normalized absorption cross-section (MAC) values for 405 nm and 532 nm at T1 increased by ~23% and ~35%, respectively, compared to the relatively less aged urban emissions at the T0 site. In contrast, the average MAC values for the 870 nm wavelength were similar for both sites. These results suggest formation of moderately brown secondary organic aerosols in biogenically-influenced urban air.

  16. The Influence of Political Decisions upon the Evolution of Renewable Energy in Romania. Case Study: Aeolian Energy

    Directory of Open Access Journals (Sweden)

    VASILE POPA

    2016-12-01

    Full Text Available It is widely accepted the fact that the foreseeable effects of the climate changes will have a major impact on the environment, and the human activities, especially fossil fuel combustion, represents the main cause of global warming. Both climate changes and the raise of the world consumption of energy and the perspective of diminishing the mineral energy resources turn the renewable energy into the main viable alternative. Between the renewable resources, the wind (Aeolian energy has a great potential. In this context, in the last few decades, as a result of the political support towards the renewable energy, the global production of wind energy has met considerable development. In Romania, the insertion of the promotion of electric energy produced by the renewable energy sources system has gathered plenty investments, leading to spectacular risings. The evolution in this domain has though been mostly influenced by the governmental policies. The repetitive changes of legislation led to an uncertain future for the Aeolian energy in Romania, on short term to say the least.

  17. Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

    Directory of Open Access Journals (Sweden)

    BRANIMIR N. GRGUR

    2005-02-01

    Full Text Available Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal–chloride complexes using cyclic voltammetry. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER and oxygen reduction (ORR reactions. Aplatinum overlayer on a gold substrate increases the activity forHER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.

  18. Influence of the heart rate and atrioventricular delays on vortex evolution and blood transport inside the left ventricle

    Science.gov (United States)

    Hendabadi, Sahar; Martinez-Legazpi, Pablo; Benito, Yolanda; Bermejo, Javier; Del Alamo, Juan Carlos; Shadden, Shawn

    2013-11-01

    Cardiac resynchronization therapy (CRT) is used to help restore coordinated pumping of the ventricles by overcoming delays in electrical conduction due to cardiac disease. This is accomplished by a specialized cardiac pacemaker that is able to adjust the atrioventricular (AV) delay.A major clinical challenge is to adjust the pacing strategy to best coordinate the blood flow mechanics of ventricular filling and ejection. To this end, we have studied the difference in the vortex formation and its evolution inside the left ventricle (LV) for 4 different AV delays in a cohort of patients with implanted pacemakers. A reconstruction algorithm was used to obtain 2D velocity over the apical long-axis view of the LV from color Doppler and B-mode ultrasound data. To study blood transport, we have identified Lagrangian coherent structures to determine moving boundaries of the blood volumes injected to the LV in diastole and ejected to the aorta in systole. In all cases, we have analyzed the differences in filling and ejection patterns and the blood transport during the E-wave and A-wave formation.Finally we have assessed the influence of the AV delay on 2 indices of stasis, direct flow and residence time.The findings shed insight to the optimization of AV delays in patients undergoing CRT. NIH award 5R21HL108268 and grants PIS09/02603 and RD06/0010 from the Plan Nacional de Investigacion Cientifica, Spain.

  19. Evolution of the Cubatão urban mangrove in São Paulo State (Brazil) over space and time

    OpenAIRE

    Flandroy, J.; Cunha-Lignon, M.; Dahdouh-Guebas, F.

    2009-01-01

    With 120,000 inhabitants and an area of 140km2 Cubatão (São Paulo State, Brazil) qualifies as an urban area. The mangrove of this coastal area occupies 136,538m2 but only 40% is in good condition. Many anthropogenic activities cause pollution, but despite these environmental impacts, the region is important for its biodiversity. The aim of this research is to study the evolution of the urban mangrove forest in Cubatão between 1962 and 2008.Imagery of 1962, 1994 and 2008 was used to detect the...

  20. The Influence of Pre-Conditioning on Space Charge Formation in LDPE

    DEFF Research Database (Denmark)

    Fleming, Robert J.; Henriksen, Mogens; Holbøll, Joachim T.

    1996-01-01

    In this paper we present space charge accumulation data for planar low density polyethylene samples subjected to 20 kV/mm dc fields at room temperature. The data were obtained using the laser-induced-pressure-pulse (LIPP) technique. Some of the samples were conditioned by holding them at 40oC in ......C in short-circuit at rotary pump pressure for 48 hr prior to measurement. Such conditioning had no consistent effect on the space charge. The extent of charge injection/extraction at the semicon electrodes appeared to vary considerably between samples....

  1. Influence of the atmosphere on the space detection of ultra-high energy cosmic rays

    International Nuclear Information System (INIS)

    Moreggia, S.

    2007-06-01

    EUSO (Extreme Universe Space Observatory) is a project of ultra-high energy (> 10 20 eV) cosmic rays detection from space. Its concept relies on the observation of fluorescence and Cerenkov photons emitted by extensive air showers from a telescope located on the International Space Station. A simulation software has been developed to study the characteristics of this innovative concept of detection. It deals with the different steps of the detection chain: extensive air shower development, emission of fluorescence and Cerenkov light, and radiative transfer to the telescope. A Monte-Carlo code has been implemented to simulate the propagation of photons through the atmosphere, dealing with multiple scattering in clear sky conditions as well as in presence of aerosols and clouds. With this simulation program, the impact of atmospheric conditions on the performance of a space-located detector has been studied. The precise treatment of photons propagation through the atmosphere has permitted to quantify the scattered light contribution to the detected signal. (author)

  2. Influence of Inter-Intra Row Spacing on Yield Losses of Tomato ...

    African Journals Online (AJOL)

    Data on major yield loss agents such as, blossom end rot, decay, insect, disease, sunburn, crack, catface and others minor disorders were collected; as well as total yield, percent of marketable and unmarketable fruit yield parameters were analyzed. Results of the study showed that inter-intra row spacing and cultivar had a ...

  3. Space Weather Influence on Relative Motion Control using the Touchless Electrostatic Tractor

    Science.gov (United States)

    Hogan, Erik A.; Schaub, Hanspeter

    2016-09-01

    With recent interest in the use of electrostatic forces for contactless tugging and attitude control of noncooperative objects for orbital servicing and active debris mitigation, the need for a method of remote charge control arises. In this paper, the use of a directed electron beam for remote charge control is considered in conjunction with the relative motion control. A tug vehicle emits an electron beam onto a deputy object, charging it negatively. At the same time, the tug is charged positively due to beam emission, resulting in an attractive electrostatic force. The relative position feedback control between the tug and the passive debris object is studied subject to the charging being created through an electron beam. Employing the nominal variations of the GEO space weather conditions across longitude slots, two electrostatic tugging strategies are considered. First, the electron beam current is adjusted throughout the orbit in order to maximize this resulting electrostatic force. This open-loop control strategy compensates for changes in the nominally expected local space weather environment in the GEO region to adjust for fluctuations in the local plasma return currents. Second, the performance impact of using a fixed electron beam current on the electrostatic tractor is studied if the same natural space weather variations are assumed. The fixed electron beam current shows a minor performance penalty (<5 %) while providing a much simpler implementation that does not require any knowledge of local space weather conditions.

  4. Influence of intra-row spacing and mulching on weed growth and ...

    African Journals Online (AJOL)

    Two field experiments were conducted during 2000/2001 and 2001/2002 dry seasons under irrigation at Kwalkwalawa Research Fadama Farm of Usmanu Danfodiyo University, Sokoto to investigate the response of weed growth and bulb yield of garlic to intra-row spacing and mulching. The treatments consisted of three ...

  5. Influence of pen area and trough space on feedlot performance of ...

    African Journals Online (AJOL)

    performance. There was no advantage in allowing more than 170 mm trough space or more than 5,5 m2 floor area per animal with the conditions and climate under which these trials were conducted ... pen area on feed intake and feedlot performance. A total of 196 dehorned ... Standard deviation (kg). 0,19. 0,18. 0,19. 0,15.

  6. Influence of sett size and spacing on yield and multiplication ratio of ...

    African Journals Online (AJOL)

    Ghana Journal of Agricultural Science ... and three spacings 12 cm W12 cm, 15 cm W 15 cm, and 15 cm W 23 cm) were studied for their ... greenhouse conditions was highest for the 10 g sett class and decreased with reduction in sett size.

  7. Influence of intra-row spacing and mulching on weed growth and ...

    African Journals Online (AJOL)

    hope&shola

    2006-02-02

    Feb 2, 2006 ... Two field experiments were conducted during 2000/2001 and 2001/2002 dry seasons under irrigation at. Kwalkwalawa Research Fadama Farm of Usmanu Danfodiyo University, Sokoto to investigate the response of weed growth and bulb yield of garlic to intra-row spacing and mulching. The treatments.

  8. The Influence of Pre-conditioning on the Space Charge Formation in LDPE and XLPE

    DEFF Research Database (Denmark)

    Henriksen, Mogens; Holbøll, Joachim T.; Fleming, R.J.

    1996-01-01

    Planar LDPE and XLPE samples were conditioned by holding in short circuit for 48 hrs. at 40oC under rotary pump pressure, and space charge accumulation in these samples under DC fields of 20 kV/mm was then compared with the corresponding accumulation in unconditioned samples.The test results were...

  9. Application of Advanced Materials Protecting from Influence of Free Space Environment

    Science.gov (United States)

    Dotsenko, Oleg; Shovkoplyas, Yuriy

    2016-07-01

    High cost and low availability of the components certified for use in the space environment forces satellite designers to using industrial and even commercial items. Risks associated with insufficient knowledge about behavior of these components in radiation environment are parried, mainly, by careful radiating designing of a satellite where application of special protective materials with improved space radiation shielding characteristics is one of the most widely used practices. Another advantage of protective materials application appears when a satellite designer needs using equipment in more severe space environment conditions then it has been provided at the equipment development. In such cases only expensive repeated qualification of the equipment hardness can be alternative to protective materials application. But mostly this way is unacceptable for satellite developers, being within strong financial and temporal restrictions. To apply protective materials effectively, the developer should have possibility to answer the question: "Where inside a satellite shall I place these materials and what shall be their shape to meet the requirements on space radiation hardness with minimal mass and volume expenses?" At that, the minimum set of requirements on space radiation hardness include: ionizing dose, nonionizing dose, single events, and internal charging. The standard calculative models and experimental techniques, now in use for space radiation hardness assurance of a satellite are unsuitable for the problem solving in such formulation. The sector analysis methodology, widely used in satellite radiating designing, is applicable only for aluminium shielding and doesn't allow taking into account advantages of protective materials. The programs simulating transport of space radiations through a substance with the use of Monte-Carlo technique, such as GEANT4, FLUKA, HZETRN and others, are fully applicable in view of their capabilities; but time required for

  10. Influence of silver on the anodic corrosion and gas evolution of Pb-Sb-As-Se alloys as positive grids in lead acid batteries

    International Nuclear Information System (INIS)

    Tizpar, A.; Ghasemi, Z.

    2006-01-01

    The influence of silver addition in the range 0.01-0.09 wt.% on the anodic corrosion and gas evolution of Pb-Sb-As-Se alloy in 1.28 sp.gr. H 2 SO 4 solution at 25 deg. C was studied using linear sweep voltammetry, cyclic voltammetry, weight loss measurements and scanning electron microscopy. The results drawn from different techniques are comparable. The effect of different concentration of silver on the corrosion behavior of Pb-Sb-As-Se was investigated. The experimental results show that the silver added to Pb-Sb-As-Se alloy inhibits the growth of anodic corrosion layer. A decrease in the oxygen evolution overpotential and an increase in the hydrogen evolution overpotential with the addition of Ag were also observed during the experiments. Cyclic voltammetric measurements provided information on the effect of Ag on the oxidation of PbSO 4 to PbO 2

  11. Does initial spacing influence crown and hydraulic architecture of Eucalyptus marginata?

    Science.gov (United States)

    Grigg, A H; Macfarlane, C; Evangelista, C; Eamus, D; Adams, M A

    2008-05-01

    Long-term declines in rainfall in south-western Australia have resulted in increased interest in the hydraulic characteristics of jarrah (Eucalyptus marginata Donn ex Smith) forest established in the region's drinking water catchments on rehabilitated bauxite mining sites. We hypothesized that in jarrah forest established on rehabilitated mine sites: (1) leaf area index (L) is independent of initial tree spacing; and (2) more densely planted trees have less leaf area for the same leaf mass, or the same sapwood area, and have denser sapwood. Initial stand densities ranged from about 600 to 9000 stems ha(-1), and trees were 18 years old at the time of sampling. Leaf area index was unaffected by initial stand density, except in the most sparsely stocked stands where L was 1.2 compared with 2.0-2.5 in stands at other spacings. The ratio of leaf area to sapwood area (A(l):A(s)) was unaffected by tree spacing or tree size and was 0.2 at 1.3 m height and 0.25 at the crown base. There were small increases in sapwood density and decreases in leaf specific area with increased spacing. Tree diameter or basal area was a better predictor of leaf area than sapwood area. At the stand scale, basal area was a good predictor of L (r(2) = 0.98, n = 15) except in the densest stands. We conclude that the hydraulic attributes of this forest type are largely independent of initial tree spacing, thus simplifying parameterization of stand and catchment water balance models.

  12. QCD and the space-time evolution of high energy e+e-, p anti p, and heavy ion collisions

    International Nuclear Information System (INIS)

    Bjorken, J.D.

    1982-06-01

    We begin with a discussion of e + e - annihilation into hadrons, a process blessed with well-known elements of simplicity. We consider the opposite extreme of highly relativistic nucleus-nucleus collisions. Here a space-time description has its own elements of simplicity, elements which might conceivably be applicable in hadron-hadron collisions. We also address the more immediate issues of how these ideas relate to present-day observations, especially high-energy hadron-hadron collisions. 40 references

  13. Influence of radioprotectors on total body weight evolution and on oxygen consumption in lethal dose irradiated animals. (Preliminary study)

    International Nuclear Information System (INIS)

    Fatome, M.; Martine, G.; Bargy, E.; Andrieu, L.

    Comparison of total body weight evolution and oxygen consumption in lethal dose irradiated animals, protected by various well known radioprotective substances, isolated or in mixture, with evolution and consumption of non protected animals irradiated at the same dose and with these of check animals [fr

  14. Simulation of space protons influence on silicon semiconductor devices using gamma-neutron irradiation

    International Nuclear Information System (INIS)

    Zhukov, Y.N.; Zinchenko, V.F.; Ulimov, V.N.

    1999-01-01

    In this study the authors focus on the problems of simulating the space proton energy spectra under laboratory gamma-neutron radiation tests of semiconductor devices (SD). A correct simulation of radiation effects implies to take into account and evaluate substantial differences in the processes of formation of primary defects in SD in space environment and under laboratory testing. These differences concern: 1) displacement defects, 2) ionization defects and 3) intensity of radiation. The study shows that: - the energy dependence of nonionizing energy loss (NIEL) is quite universal to predict the degradation of SD parameters associated to displacement defects, and - MOS devices that are sensitive to ionization defects indicated the same variation of parameters under conditions of equality of ionization density generated by protons and gamma radiations. (A.C.)

  15. The influence of oxidation on space charge formation in gamma-irradiated low-density polyethylene

    CERN Document Server

    Chen, G; Xie, H K; Banford, H M; Davies, A E

    2003-01-01

    The research presented in this paper investigates the role of oxidation in the formation of space charge in gamma-irradiated low-density polyethylene after being electrically stressed under dc voltage. Polyethylene plaques both with and without antioxidant were irradiated up to 500 kGy using a sup 6 sup 0 Co gamma source and space charge distributions were measured using the piezoelectric induced pressure wave propagation method. It has been found that a large amount of positive charge evolved adjacent to the cathode in the sample without antioxidant and was clearly associated with oxidation of the surface. The amount of charge formed for a given applied stress increased with the dose absorbed by the material. A model has been proposed to explain the formation of space charge and its profile. The charge decay after the removal of the external applied stress is dominated by a process being controlled by the cathode interfacial stress (charge injection) rather than a conventional RC circuit model. On the other ...

  16. Influence of the heat losses and accumulated heat upon the evolution of the thermohydraulic processes in the transients as applied to the ISB-WWER integral test facility

    International Nuclear Information System (INIS)

    Gashenko, I.V.; Melikhov, O.I.; Shmal, I.I.; Kouznetsov, V.D.

    2001-01-01

    The results of the calculational study using the RELAP5/MOD3.2 thermalhydraulic code performed on the influence of the heat losses to the ambient and the heat accumulated in the pipelines walls upon the evolution of the thermalhydraulic processes in the primary circuit of the integral test facility ISB-WWER when simulating the transients caused by the loss of the coolant are presented in the paper. (authors)

  17. Spacelab 1 hematology experiment (INS103): Influence of space flight on erythrokinetics in man

    Science.gov (United States)

    Leach, C. S.; Chen, J. P.; Crosby, W.; Dunn, C. D. R.; Johnson, P. C.; Lange, R. D.; Larkin, E.; Tavassoli, M.

    1985-01-01

    An experiment conducted on the 10-day Spacelab 1 mission aboard the ninth Space Shuttle flight in November to December 1983 was designed to measure factors involved in the control of erythrocyte turnover that might be altered during weightlessness. Blood samples were collected before, during, and after the flight. Immediately after landing, red cell mass showed a mean decrease of 9.3 percent in the four astronauts. Neither hyperoxia nor an increase in blood phosphate was a cause of the decrease. Red cell survival time and iron incorporation postflight were not significantly different from their preflight levels. Serum haptoglobin did not decrease, indicating that intravascular hemolysis was not a major cause of red cell mass change. An increase in serum ferritin after the second day of flight may have been caused by red cell breakdown early in flight. Erythropoietin levels decreased during and after flight, but preflight levels were high and the decrease was not significant. The space flight-induced decrease in red cell mass may result from a failure of erythropoiesis to replace cells destroyed by the spleen soon after weightlessness is attained.

  18. Factors Influencing Visitors to Suburban Open Space Areas near a Northern Japanese City

    Directory of Open Access Journals (Sweden)

    Yasushi Shoji

    2012-04-01

    Full Text Available Visitor information often serves as the basis for the management plan of parks. However, there exist few scientific and fundamental surveys for parks and open spaces in Japan. We analyzed the correlation between the number of visitors and the various factors in a suburban open space in a northern Japanese city, Takino Park. To explain the fluctuations in the number of visitors in Takino Park, multiple regression analyses with the stepwise method were conducted. The analyses employed social factors and meteorological factors, such as the day of the week, school vacations, temperature and the weather. The results show that the most influential factor is the day of the week, i.e., Sundays and holidays. The weather is also influential as the number of visitors decreases on rainy and snowy days. Comparing different seasons of the year, we found that influential factors varied from one season to the other. A key distinguishing finding of our results is that the weather conditions at the departure site and the weather forecast are also determining factors. These findings will help park managers understand the current situations and examine future management strategies to maintain and enhance visitor satisfaction, and improve information services.

  19. UV Luminosity Functions at z~4, 5, and 6 from the Hubble Ultra Deep Field and Other Deep Hubble Space Telescope ACS Fields: Evolution and Star Formation History

    Science.gov (United States)

    Bouwens, R. J.; Illingworth, G. D.; Franx, Marijn; Ford, Holland

    2007-12-01

    We use the ACS BViz data from the HUDF and all other deep HST ACS fields (including the GOODS fields) to find large samples of star-forming galaxies at z~4 and ~5 and to extend our previous z~6 sample. These samples contain 4671, 1416, and 627 B-, V-, and i-dropouts, respectively, and reach to extremely low luminosities [(0.01-0.04)L*z=3 or MUV~-16 to -17], allowing us to determine the rest-frame UV LF and faint-end slope α at z~4-6 to high accuracy. We find faint-end slopes α=-1.73+/-0.05, -1.66+/-0.09, and -1.74+/-0.16 at z~4, ~5, and ~6, respectively, suggesting that the faint-end slope is very steep and shows little evolution with cosmic time. We find that M*UV brightens considerably in the 0.7 Gyr from z~6 to ~4 (by ~0.7 mag from M*UV=-20.24+/-0.19 to -20.98+/-0.10). The observed increase in the characteristic luminosity over this range is almost identical to that expected for the halo mass function, suggesting that the observed evolution is likely due to the hierarchical coalescence and merging of galaxies. The evolution in φ* is not significant. The UV luminosity density at z~6 is modestly lower than (0.45+/-0.09 times) that at z~4 (integrated to -17.5 mag) although a larger change is seen in the dust-corrected SFR density. We thoroughly examine published LF results and assess the reasons for their wide dispersion. We argue that the results reported here are the most robust available. The extremely steep faint-end slopes α found here suggest that lower luminosity galaxies play a significant role in reionizing the universe. Finally, recent search results for galaxies at z~7-8 are used to extend our estimates of the evolution of M* from z~7-8 to z~4. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 9425, 9575, 9803, 9978, 10189, 10339, 10340, and 10632.

  20. Evolution of the military and social research in post-soviet space for the period 1993-2013 years

    Directory of Open Access Journals (Sweden)

    Yu. A. Kalahin

    2013-12-01

    The results showed that during the period from 1993 to 2013 on sociological subjects were protected by 82 theses. The most studied problems of military organization management processes are found in the military organization, its social structure. Less studied the economic aspects of the military organization. The study of the dynamics of military sociological research has shown that the problems of the social structure of the military organization in the long term remain valid. The economic aspects of the military organization only become relevant. It’s a natural tendency, which reflects the influence of both objective and subjective factors at the present stage of reforming the military organization.

  1. Evolution of the Deep-space Galactic Cosmic Ray Lineal Energy Transfer Spectrum through Tissue Equivalent Plastic

    Science.gov (United States)

    Case, A. W.; Kasper, J. C.; Spence, H. E.; Golightly, M. J.; Schwadron, N. A.; Mazur, J. E.; Blake, J. B.; Looper, M. D.; Townsend, L.; Zeitlin, C. J.

    2011-12-01

    The Cosmic Ray Telescope for the Effects of Radiation is an energetic particle telescope that resides on the Lunar Reconnaissance Orbiter spacecraft, currently in a 50 km circular lunar polar orbit. The telescope consists of 6 silicon semi-conductor detectors placed in pairs that surround two pieces of Tissue Equivalent Plastic (TEP), which serve to absorb energy from particles as they transit through the instrument. Particles with energies greater than 12 MeV/nucleon can penetrate the outermost shield and be measured by the instrument. The primary measurement made by the instrument is of the Linear Energy Transfer (LET) of energetic particles as they transit through the telescope. CRaTER measures the LET spectrum with unprecedented energy resolution and has done so during a period of historically low solar activity that led to record high intensities of Galactic Cosmic Rays (GCR). These LET spectra are used to study changes in the properties of the incoming particles, and to make detailed measurements of the radiation doses human explorers will experience in deep space on missions to the moon, to asteroids, or to Mars. We present LET spectra accumulated during 2009 and 2010. We show how the LET spectrum evolves through the instrument as the GCR interact with the TEP. Due to the importance of these measurements for human effects, our extensive absolute calibration procedures are presented. Of particular note is a significant reduction in the flux of particles with LET greater than 10 keV/um for detectors that lie deeper within the telescope stack, due to the attenuation of high LET particles within the TEP. By measuring this attenuation we can estimate the depth in human tissue where the highest LET particles that are most likely to cause genetic damage pose the greatest threat to humans in space.

  2. Influence of the radial spacing between cathodes on the surface composition of iron samples sintered by hollow cathode electric discharge

    Directory of Open Access Journals (Sweden)

    Brunatto S.F.

    2001-01-01

    Full Text Available The present work reports an investigation of the influence of the radial spacing between cathodes on the iron sintering process by hollow cathode electrical discharge, with surface enrichment of the alloying elements Cr and Ni. Pressed cylindrical samples of 9.5 mm diameter and density of 7.0 ± 0.1 g/cm³ were prepared by compaction of Ancorsteel 1000C iron powder. These samples, constituting the central cathode, were positioned concentrically in the interior of an external cathode machined from a tube of stainless steel AISI 310 (containing: 25% Cr, 16% Ni, 1.5% Mn, 1.5% Si, 0.03% C and the remainder Fe. Sintering was done at 1150 °C, for 120 min, utilizing radial spacings between the central and hollow cathodes of 3, 6 and 9 mm and a gas mixture of 80% Ar and 20% H2, with a flow rate of 5 cm³/s at a pressure of 3 Torr. The electric discharge was generated using a pulsed voltage power source, with a period of 200 mus. The radial spacing had only a slight influence on the quantity of atoms of alloying elements deposited and diffused on the surface of the sample. Analysis with a microprobe showed the presence of chrome (up to 4.0% and nickel (up to 3.0%, in at. % at the surface of the samples. This surface enrichment can be attributed to the mechanism of sputtering of the metallic atoms present in the external cathode, with the deposition of these elements on the sample surface and consequent diffusion within the sample.

  3. Influence of pre-existing basement faults on the structural evolution of the Zagros Simply Folded belt: 3D numerical modelling

    Science.gov (United States)

    Ruh, Jonas B.; Gerya, Taras

    2015-04-01

    The Simply Folded Belt of the Zagros orogen is characterized by elongated fold trains symptomatically defining the geomorphology along this mountain range. The Zagros orogen results from the collision of the Arabian and the Eurasian plates. The Simply Folded Belt is located southwest of the Zagros suture zone. An up to 2 km thick salt horizon below the sedimentary sequence enables mechanical and structural detachment from the underlying Arabian basement. Nevertheless, deformation within the basement influences the structural evolution of the Simply Folded Belt. It has been shown that thrusts in form of reactivated normal faults can trigger out-of-sequence deformation within the sedimentary stratigraphy. Furthermore, deeply rooted strike-slip faults, such as the Kazerun faults between the Fars zone in the southeast and the Dezful embayment and the Izeh zone, are largely dispersing into the overlying stratigraphy, strongly influencing the tectonic evolution and mechanical behaviour. The aim of this study is to reveal the influence of basement thrusts and strike-slip faults on the structural evolution of the Simply Folded Belt depending on the occurrence of intercrustal weak horizons (Hormuz salt) and the rheology and thermal structure of the basement. Therefore, we present high-resolution 3D thermo-mechnical models with pre-existing, inversively reactivated normal faults or strike-slip faults within the basement. Numerical models are based on finite difference, marker-in-cell technique with (power-law) visco-plastic rheology accounting for brittle deformation. Preliminary results show that deep tectonic structures present in the basement may have crucial effects on the morphology and evolution of a fold-and-thrust belt above a major detachment horizon.

  4. Evolution of multispectral aerosol optical properties in a biogenically-influenced urban environment during the CARES campaign

    Science.gov (United States)

    Gyawali, M.; Arnott, W. P.; Zaveri, R. A.; Song, C.; Pekour, M.; Flowers, B.; Dubey, M. K.; Setyan, A.; Zhang, Q.; Harworth, J. W.; Radney, J. G.; Atkinson, D. B.; China, S.; Mazzoleni, C.; Gorkowski, K.; Subramanian, R.; Jobson, B. T.; Moosmüller, H.

    2013-03-01

    Ground-based aerosol measurements made in June 2010 within Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area are used to investigate the evolution of multispectral optical properties as the urban aerosols aged and interacted with biogenic emissions. Along with black carbon and non-refractory aerosol mass and composition observations, spectral absorptio (βabs), scattering (βsca), and extinction (βext) coefficients for wavelengths ranging from 355 to 1064 nm were measured at both sites using photoacoustic (PA) instruments with integrating nephelometers and using cavity ring-down (CRD) instruments. The daytime average Ångström exponent of absorption (AEA) was ~1.6 for the wavelength pair 405 and 870 nm at T0, while it was ~1.8 for the wavelength pair 355 and 870 nm at T1, indicating a modest wavelength-dependent enhancement of absorption at both sites throughout the study. The measured and Mie theory calculations of multispectral βsca showed good correlation (R2=0.85-0.94). The average contribution of supermicron aerosol (mainly composed of sea salt particles advected in from the Pacific Ocean) to the total scattering coefficient ranged from less than 20% at 405 nm to greater than 80% at 1064 nm. From 22 to 28 June, secondary organic aerosol mass increased significantly at both sites due to increased biogenic emissions coupled with intense photochemical activity and air mass recirculation in the area. During this period, the short wavelength scattering coefficients at both sites gradually increased due to increase in the size of submicron aerosols. At the same time, BC mass-normalized absorption cross-section (MAC) values for ultraviolet wavelengths at T1 increased by ~60% compared to the relatively less aged urban emissions at the T0 site. In contrast, the average MAC values for 870 nm wavelength were identical at both sites. These results suggest formation of moderately brown secondary

  5. INFLUENCE OF ECOLOGICAL GROUP COMPOSITION, PLANTATION SPACING AND ARRANGEMENT IN THE RESTORATION OF RIPARIAN FOREST ON RESERVOIR SHORES

    Directory of Open Access Journals (Sweden)

    Alvaro Augusto Vieira Soares

    2016-01-01

    Full Text Available This work aimed to assess the effect of spacing, arrangement and ecological group composition of planted seedlings on the restoration process of artificial reservoir shores in southeastern Brazil. The assessments were performed 12 years after the settlement of the experiment in which five mixed stand models were tested. First, a general evaluation of the stand was performed when we surveyed the overstory and understory, seed bank and soil for chemical analysis.Then, the restoration indicators survival of planted trees, basal area and density of the tree community, litter accumulated on the soil and canopy closure index were utilized to compare the plantation models and to assess the influence the experimental factors on these parameters. In the general analysis, we found that the studied stand presents low diversity, poor regeneration, and seed bank dominated mostly by one planted exotic tree species and weeds, which may jeopardize the self- maintenance of the stand in the future. The factor that most influenced the models was the ecological group composition with the best performance found for models in which both pioneer and non-pioneer groups were used. Probably, the plantation arrangement and spacing did not have greater influence due to both plant mortality and natural regeneration that has developed to this age. Hence, it is not recommended the use of only pioneer species in the implantation of riparian forest and the proportion of 50% pioneers and 50% non-pioneers using as much species as possible is indicated for areas that might present constraints for the natural regeneration.

  6. Water Tree Influence on Space Charge Distribution and on the Residual Electric Field in Polyethylene Insulation

    Directory of Open Access Journals (Sweden)

    Cristina Stancu

    2009-10-01

    Full Text Available A computation method of the electricfield and ionic space charge density in planeinsulations with water trees (using a ComsolMultiphysics software and the thermal step currents(Im(t measured with Thermal Step Method ispresented. A parabolic spatial variation of volumecharge density, an exponential spatial variation ofthe electric permittivity ε and a linear dependency ofε and the temperature coefficient of permittivity αεwith the average water concentration in trees, areconsidered. For a water tree with a known length,different values of charge density are consideredand the electric field and the thermal step currentsIc(t are calculated. The currents Ic(t and Im(t arecompared and the volume of charge density andelectric field for which Ic(t is identical with Im(t arekept.

  7. Grounding grammatical categories: attention bias in hand space influences grammatical congruency judgment of Chinese nominal classifiers.

    Science.gov (United States)

    Lobben, Marit; D'Ascenzo, Stefania

    2015-01-01

    Embodied cognitive theories predict that linguistic conceptual representations are grounded and continually represented in real world, sensorimotor experiences. However, there is an on-going debate on whether this also holds for abstract concepts. Grammar is the archetype of abstract knowledge, and therefore constitutes a test case against embodied theories of language representation. Former studies have largely focussed on lexical-level embodied representations. In the present study we take the grounding-by-modality idea a step further by using reaction time (RT) data from the linguistic processing of nominal classifiers in Chinese. We take advantage of an independent body of research, which shows that attention in hand space is biased. Specifically, objects near the hand consistently yield shorter RTs as a function of readiness for action on graspable objects within reaching space, and the same biased attention inhibits attentional disengagement. We predicted that this attention bias would equally apply to the graspable object classifier but not to the big object classifier. Chinese speakers (N = 22) judged grammatical congruency of classifier-noun combinations in two conditions: graspable object classifier and big object classifier. We found that RTs for the graspable object classifier were significantly faster in congruent combinations, and significantly slower in incongruent combinations, than the big object classifier. There was no main effect on grammatical violations, but rather an interaction effect of classifier type. Thus, we demonstrate here grammatical category-specific effects pertaining to the semantic content and by extension the visual and tactile modality of acquisition underlying the acquisition of these categories. We conclude that abstract grammatical categories are subjected to the same mechanisms as general cognitive and neurophysiological processes and may therefore be grounded.

  8. Influence of Music on the Behaviors of Crowd in Urban Open Public Spaces.

    Science.gov (United States)

    Meng, Qi; Zhao, Tingting; Kang, Jian

    2018-01-01

    Sound environment plays an important role in urban open spaces, yet studies on the effects of perception of the sound environment on crowd behaviors have been limited. The aim of this study, therefore, is to explore how music, which is considered an important soundscape element, affects crowd behaviors in urban open spaces. On-site observations were performed at a 100 m × 70 m urban leisure square in Harbin, China. Typical music was used to study the effects of perception of the sound environment on crowd behaviors; then, these behaviors were classified into movement (passing by and walking around) and non-movement behaviors (sitting). The results show that the path of passing by in an urban leisure square with music was more centralized than without music. Without music, 8.3% of people passing by walked near the edge of the square, whereas with music, this percentage was zero. In terms of the speed of passing by behavior, no significant difference was observed with the presence or absence of background music. Regarding the effect of music on walking around behavior in the square, the mean area and perimeter when background music was played were smaller than without background music. The mean speed of those exhibiting walking around behavior with background music in the square was 0.296 m/s slower than when no background music was played. For those exhibiting sitting behavior, when background music was not present, crowd density showed no variation based on the distance from the sound source. When music was present, it was observed that as the distance from the sound source increased, crowd density of those sitting behavior decreased accordingly.

  9. Thermal cycling damage evolution of a thermal barrier coating and the influence of substrate creep, interface roughness and pre-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Schweda, Mario; Beck, Tilmann; Singheiser, Lorenz [Forschungszentrum Juelich GmbH (DE). Inst. fuer Energie- und Klimaforschung (IEK), Werkstoffstruktur und Eigenschaften (IEK-2)

    2012-01-15

    The influence of roughness profile shape, roughness depth, bond coat creep strength and pre-oxidation on the thermal cycling damage evolution and lifetime of a plasma-sprayed ZrO{sub 2} thermal barrier coating system was investigated. A simplified model system was used where FeCrAlY substrates simulated the bond coat. Substrate creep was varied by using the oxide dispersoid strengthened alloy MA956 and the conventional material Fecralloy. Stochastic 3- and periodic 2-dimensional roughness profiles were produced by sand blasting and high speed turning. Damage evolution is significantly influenced by substrate creep with a trend to higher lifetimes for the fast creeping substrate. Pre-oxidation has no influence. Lifetimes of the periodically profiled samples are up to 100 times lower than these of stochastically profiled samples. In the case of periodically profiled samples, the highest lifetime was reached for the highest roughness depth combined with local undercuttings in the roughness profile. For stochastically profiled samples the influence of roughness depth could not be determined due to the wide lifetime scatter. (orig.)

  10. Electronic structure and optical properties of twisted bilayer graphene calculated via time evolution of states in real space

    Science.gov (United States)

    Le, H. Anh; Do, V. Nam

    2018-03-01

    We investigate the electronic and optical properties of twisted bilayer graphene with arbitrary twist angles θ . Our results are based on a method of evolving in time quantum states in lattice space. We propose an efficient scheme of sampling lattice nodes that helps to reduce significantly computational cost, particularly for tiny twist angles. We demonstrate the continuous variation of the density of states and the optical conductivity with respect to the twist angle. It indicates that the commensurability between the two graphene layers does not play an essential role in governing the electronic and optical properties. We point out that, for the twist angles roughly in the range 0 .1∘energy exhibits the typical W shape with a small peak locating at the Fermi energy. This peak is formed as the merging of two van Hove peaks and reflects the appearance of states strongly localized in the AA-like region of moiré zones. When decreasing the twist angle to zero, the W shape is gradually transformed to the U shape, which is seen as the behavior of the density of states in the limit of θ →0∘ .

  11. SIMULATION FROM ENDPOINT-CONDITIONED, CONTINUOUS-TIME MARKOV CHAINS ON A FINITE STATE SPACE, WITH APPLICATIONS TO MOLECULAR EVOLUTION.

    Science.gov (United States)

    Hobolth, Asger; Stone, Eric A

    2009-09-01

    Analyses of serially-sampled data often begin with the assumption that the observations represent discrete samples from a latent continuous-time stochastic process. The continuous-time Markov chain (CTMC) is one such generative model whose popularity extends to a variety of disciplines ranging from computational finance to human genetics and genomics. A common theme among these diverse applications is the need to simulate sample paths of a CTMC conditional on realized data that is discretely observed. Here we present a general solution to this sampling problem when the CTMC is defined on a discrete and finite state space. Specifically, we consider the generation of sample paths, including intermediate states and times of transition, from a CTMC whose beginning and ending states are known across a time interval of length T. We first unify the literature through a discussion of the three predominant approaches: (1) modified rejection sampling, (2) direct sampling, and (3) uniformization. We then give analytical results for the complexity and efficiency of each method in terms of the instantaneous transition rate matrix Q of the CTMC, its beginning and ending states, and the length of sampling time T. In doing so, we show that no method dominates the others across all model specifications, and we give explicit proof of which method prevails for any given Q, T, and endpoints. Finally, we introduce and compare three applications of CTMCs to demonstrate the pitfalls of choosing an inefficient sampler.

  12. Influence of crystal shapes on radiative fluxes in visible wavelength: ice crystals randomly oriented in space

    Directory of Open Access Journals (Sweden)

    P. Chervet

    1996-08-01

    Full Text Available Radiative properties of cirrus clouds are one of the major unsolved problems in climate studies and global radiation budget. These clouds are generally composed of various ice-crystal shapes, so we tried to evaluate effects of the ice-crystal shape on radiative fluxes. We calculated radiative fluxes of cirrus clouds with a constant geometrical depth, composed of ice crystals with different shapes (hexagonal columns, bullets, bullet-rosettes, sizes and various concentrations. We considered ice particles randomly oriented in space (3D case and their scattering phase functions were calculated by a ray-tracing method. We calculated radiative fluxes for cirrus layers for different microphysical characteristics by using a discrete-ordinate radiative code. Results showed that the foremost effect of the ice-crystal shape on radiative properties of cirrus clouds was that on the optical thickness, while the variation of the scattering phase function with the ice shape remained less than 3% for our computations. The ice-water content may be a better choice to parameterize the optical properties of cirrus, but the shape effect must be included.

  13. Cosmic rays and other space weather effects influenced on satellite operation, technologies, biosphere and people health

    Science.gov (United States)

    Lev, Dorman

    2016-07-01

    Satellite anomalies (or malfunctions), including total distortion of electronics and loose of some satellites cost for Insurance Companies billions dollars per year. During especially active periods the probability of big satellite anomalies and their loosing increased very much. Now, when a great number of civil and military satellites are continuously worked for our practice life, the problem of satellite anomalies became very important. Many years ago about half of satellite anomalies were caused by technical reasons (for example, for Russian satellites Kosmos), but with time with increasing of production quality, this part became smaller and smaller. The other part, which now is dominated, caused by different space weather effects (energetic particles of CR and generated/trapped in the magnetosphere, and so on). We consider only satellite anomalies not caused by technical reasons: the total number of such anomalies about 6000 events, and separately for high and low altitude orbit satellites (5000 and about 800 events, correspondingly for high and low altitude satellites). No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and solar proton event onsets for high (>1500 km) and low (railway operation (possible, through induction currents), catastrophes in long-distance electric power lines and transformators, and in other ground technologies.

  14. Space space space

    CERN Document Server

    Trembach, Vera

    2014-01-01

    Space is an introduction to the mysteries of the Universe. Included are Task Cards for independent learning, Journal Word Cards for creative writing, and Hands-On Activities for reinforcing skills in Math and Language Arts. Space is a perfect introduction to further research of the Solar System.

  15. Radiation-induced lung damage in rats: The influence of fraction spacing on effect per fraction

    International Nuclear Information System (INIS)

    Haston, C.K.; Hill, R.P.; Newcomb, C.H.; Van Dyk, J.

    1994-01-01

    When the linear-quadratic model is used to predict fractionated treatments which are isoeffective, it is usually assumed that each (equal size) treatment fraction has an equal effect, independent of the time at which it was delivered during a course of treatment. Previous work has indicated that this assumption may not be valid in the context of radiation-induced lung damage in rats. Consequently the authors tested directly the validity of the assumption that each fraction has an equal effect, independent of the time it is delivered. An experiment was completed in which fractionated irradiation was given to whole thoraces of Sprague-Dawley rats. All treatment schedules consisted of eleven equal dose fractions in 36 days given as a split course, with some groups receiving the bulk of the doses early in the treatment schedule, before a 27-day gap, and others receiving most of the dose toward the end of the treatment schedule, after the time gap. To monitor the incidence of radiation-induced damage, breathing rate and lethality assays were used. The maximum differences in the LD 50 s and breathing rate ED 50 s for the different fractionation schedules were 4.0% and 7.7% respectively. The lethality data and breathing rate data were consistent with results expected from modelling using the linear-quadratic model with the inclusion of an overall time factor, but not the generalized linear-quadratic model which accounted for fraction spacing. For conventional daily fractionation, and within the range of experimental uncertainties, the results indicate that the effect of a treatment fraction does not depend on the time at which it is given (its position) in the treatment. The results indicate no need to extend isoeffect formulae to consider the effect of each fraction separately for radiation-induced lung damage. 21 refs., 6 figs., 3 tabs

  16. Cross-species correlation between queen mating numbers and worker ovary sizes suggests kin conflict may influence ovary size evolution in honeybees

    Science.gov (United States)

    Rueppell, Olav; Phaincharoen, Mananya; Kuster, Ryan; Tingek, Salim

    2011-09-01

    During social evolution, the ovary size of reproductively specialized honey bee queens has dramatically increased while their workers have evolved much smaller ovaries. However, worker division of labor and reproductive competition under queenless conditions are influenced by worker ovary size. Little comparative information on ovary size exists in the different honey bee species. Here, we report ovariole numbers of freshly dissected workers from six Apis species from two locations in Southeast Asia. The average number of worker ovarioles differs significantly among species. It is strongly correlated with the average mating number of queens, irrespective of body size. Apis dorsata, in particular, is characterized by numerous matings and very large worker ovaries. The relation between queen mating number and ovary size across the six species suggests that individual selection via reproductive competition plays a role in worker ovary size evolution. This indicates that genetic diversity, generated by multiple mating, may bear a fitness cost at the colony level.

  17. Limits of principal components analysis for producing a common trait space: implications for inferring selection, contingency, and chance in evolution.

    Directory of Open Access Journals (Sweden)

    Kevin J Parsons

    2009-11-01

    Full Text Available Comparing patterns of divergence among separate lineages or groups has posed an especially difficult challenge for biologists. Recently a new, conceptually simple methodology called the "ordered-axis plot" approach was introduced for the purpose of comparing patterns of diversity in a common morphospace. This technique involves a combination of principal components analysis (PCA and linear regression. Given the common use of these statistics the potential for the widespread use of the ordered axis approach is high. However, there are a number of drawbacks to this approach, most notably that lineages with the greatest amount of variance will largely bias interpretations from analyses involving a common morphospace. Therefore, without meeting a set of a priori requirements regarding data structure the ordered-axis plot approach will likely produce misleading results.Morphological data sets from cichlid fishes endemic to Lakes Tanganyika, Malawi, and Victoria were used to statistically demonstrate how separate groups can have differing contributions to a common morphospace produced by a PCA. Through a matrix superimposition of eigenvectors (scale-free trajectories of variation identified by PCA we show that some groups contribute more to the trajectories of variation identified in a common morphospace. Furthermore, through a set of randomization tests we show that a common morphospace model partitions variation differently than group-specific models. Finally, we demonstrate how these limitations may influence an ordered-axis plot approach by performing a comparison on data sets with known alterations in covariance structure. Using these results we provide a set of criteria that must be met before a common morphospace can be reliably used.Our results suggest that a common morphospace produced by PCA would not be useful for producing biologically meaningful results unless a restrictive set of criteria are met. We therefore suggest biologists be aware

  18. Geometric influences of a particle confined to a curved surface embedded in three-dimensional Euclidean space

    Science.gov (United States)

    Wang, Yong-Long; Jiang, Hua; Zong, Hong-Shi

    2017-08-01

    In the spirit of the thin-layer quantization approach, we give the formula of the geometric influences of a particle confined to a curved surface embedded in three-dimensional Euclidean space. The geometric contributions can result from the reduced commutation relation between the acted function depending on normal variable and the normal derivative. According to the formula, we obtain the geometric potential, geometric momentum, geometric orbital angular momentum, geometric linear Rashba, and cubic Dresselhaus spin-orbit couplings. As an example, a truncated cone surface is considered. We find that the geometric orbital angular momentum can provide an azimuthal polarization for spin, and the sign of the geometric Dresselhaus spin-orbit coupling can be flipped through the inclination angle of generatrix.

  19. The influence of the space between the billets on the productivity of a continuous walking-beam furnace

    Energy Technology Data Exchange (ETDEWEB)

    Jaklic, A. [Institute of Metals and Technology, Ljubljana (Slovenia); Kolenko, T. [University of Ljubljana (Slovenia). Faculty of Natural Science and Technology; Zupancic, B. [University of Ljubljana (Slovenia). Faculty of Electrical Engineering

    2005-04-01

    This paper presents a study of the influence of the space between billets on the productivity of a continuous walking-beam furnace. The study was performed using a simulation model of a billet-reheating process for three different billet dimensions. The simulation model considered the exact geometry of the furnace enclosure, including the geometry of the billets inside the furnace. A view-factor matrix of the furnace enclosure was determined using the Monte Carlo method. The heat exchange between the furnace gas, the furnace wall and the billet's surface was calculated using a three-temperature model. The temperature of the furnace floor was determined using a heat-balance equation, and the heat conduction in the billets was calculated using the 3D finite-difference method. The model was validated using measurements from trailing thermocouples positioned in the test billet during the reheating process in the furnace. (author)

  20. Gravitational influences on the liquid-state homogenization and solidification of aluminum antimonide. [space processing of solar cell material

    Science.gov (United States)

    Ang, C.-Y.; Lacy, L. L.

    1979-01-01

    Typical commercial or laboratory-prepared samples of polycrystalline AlSb contain microstructural inhomogeneities of Al- or Sb-rich phases in addition to the primary AlSb grains. The paper reports on gravitational influences, such as density-driven convection or sedimentation, that cause microscopic phase separation and nonequilibrium conditions to exist in earth-based melts of AlSb. A triple-cavity electric furnace is used to homogenize the multiphase AlSb samples in space and on earth. A comparative characterization of identically processed low- and one-gravity samples of commercial AlSb reveals major improvements in the homogeneity of the low-gravity homogenized material.

  1. The Significance of the Influence of the CME Deflection in Interplanetary Space on the CME Arrival at Earth

    Science.gov (United States)

    Zhuang, Bin; Wang, Yuming; Shen, Chenglong; Liu, Siqing; Wang, Jingjing; Pan, Zonghao; Li, Huimin; Liu, Rui

    2017-08-01

    As one of the most violent astrophysical phenomena, coronal mass ejections (CMEs) have strong potential space weather effects. However, not all Earth-directed CMEs encounter the Earth and produce geo-effects. One reason is the deflected propagation of CMEs in interplanetary space. Although there have been several case studies clearly showing such deflections, it has not yet been statistically assessed how significantly the deflected propagation would influence the CME’s arrival at Earth. We develop an integrated CME-arrival forecasting (iCAF) system, assembling the modules of CME detection, three-dimensional (3D) parameter derivation, and trajectory reconstruction to predict whether or not a CME arrives at Earth, and we assess the deflection influence on the CME-arrival forecasting. The performance of iCAF is tested by comparing the two-dimensional (2D) parameters with those in the Coordinated Data Analysis Workshop (CDAW) Data Center catalog, comparing the 3D parameters with those of the gradual cylindrical shell model, and estimating the success rate of the CME Earth-arrival predictions. It is found that the 2D parameters provided by iCAF and the CDAW catalog are consistent with each other, and the 3D parameters derived by the ice cream cone model based on single-view observations are acceptable. The success rate of the CME-arrival predictions by iCAF with deflection considered is about 82%, which is 19% higher than that without deflection, indicating the importance of the CME deflection for providing a reliable forecasting. Furthermore, iCAF is a worthwhile project since it is a completely automatic system with deflection taken into account.

  2. Influence of jet thrust on penetrator penetration when studying the structure of space object blanket

    Directory of Open Access Journals (Sweden)

    N. A. Fedorova

    2014-01-01

    Full Text Available The article presents the calculation-and-theory-based research results to examine the possibility for using the jet thrust impulse to increase a penetration depth of high-velocity penetrator modules. Such devices can be used for studies of Earth surface layer composition, and in the nearest future for other Solar system bodies too. Research equipment (sensors and different instruments is housed inside a metal body of the penetrator with a sharpened nose that decreases drag force in soil. It was assumed, that this penetrator is additionally equipped with the pulse jet engine, which is fired at a certain stage of penetrator motion into target.The penetrator is considered as a rigid body of variable mass, which is subjected to drag force and reactive force applied at the moment the engine fires. A drag force was represented with a binomial empirical law, and penetrator nose part was considered to be conical. The jet thrust force was supposed to be constant during its application time. It was in accordance with assumption that mass flow and flow rate of solid propellant combustion products were constant. The amount of propellant in the penetrator was characterized by Tsiolkovsky number Z, which specifies the ratio between the fuel mass and the penetrator structure mass with no fuel.The system of equations to describe the penetrator dynamics was given in dimensionless form using the values aligned with penetration of an equivalent inert penetrator as the time and penetration depth scales. Penetration dynamics of penetrator represented in this form allowed to eliminate the influence of penetrator initial mass and its cross-section diameter on the solution results. The lack of such dependency is convenient for comparing the calculation results since they hold for penetrators of various initial masses and cross-sections.To calculate the penetration a lunar regolith was taken as a soil material. Calculations were carried out for initial velocities of

  3. Influence of Using Clinical Microscope as Auxiliary to Perform Mechanical Cleaning of Post Space: A Bond Strength Analysis.

    Science.gov (United States)

    Ferreira, Ricardo; Prado, Maíra; de Jesus Soares, Adriana; Zaia, Alexandre Augusto; de Souza-Filho, Francisco José

    2015-08-01

    The aim of the present study was to evaluate the influence of using a clinical microscope while performing mechanical cleaning of post space walls on the bond strength of a fiberglass post to dentin. Forty-five bovine roots were used. After preparation, roots were filled using gutta-percha and Pulp Canal Sealer (SybronEndo, Orange, CA). Subsequently, for post space preparation, the roots were divided into 3 groups: control (only heat condenser + specific bur of the post system); cleaning without a microscope, mechanical cleaning (after the procedure described in the control group, round burs were used to improve cleaning); and cleaning with a microscope, mechanical cleaning performed with round burs visualized under a clinical microscope. Then, fiberglass posts were cemented. The roots were prepared and evaluated by the push-out test. Data were analyzed using Kruskal-Wallis and Student-Newman-Keuls tests (P microscope (cervical 1.66 ± 2.3, middle 0.65 ± 1.1, apical 0.79 ± 1.2, and total1.04 ± 1.7), and cleaning with a microscope (cervical 3.26 ± 2.8, middle 1.97 ± 3.5, apical 1.85 ± 4.1, and total 2.37 ± 3.5). In the cleaning with a microscope group, the bond strength values were significantly higher than those in the other groups. In all groups, the main failure pattern was adhesive between cement and dentin. The use of a clinical microscope while performing mechanical cleaning during post space preparation improved the bond strength of a fiberglass post to dentin. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  4. Understanding and Modeling the Evolution of Critical Points under Gaussian Blurring

    NARCIS (Netherlands)

    Kuijper, A.; Florack, L.M.J.; Heyden, A.; Sparr, G.; Nielsen, M.; Johansen, P.

    2002-01-01

    In order to investigate the deep structure of Gaussian scale space images, one needs to understand the behaviour of critical points under the influence of parameter-driven blurring. During this evolution two different types of special points are encountered, the so-called scale space saddles and the

  5. Influence of the intermediate bcc phase on the evolution of superfluid inclusions in hcp matrix 3He-4He

    International Nuclear Information System (INIS)

    Birchenko, A.P.; Mikhin, N.P.; Neoneta, A.S.; Rudavskij, Eh.Ya.; Fisun, Ya.Yu.

    2016-01-01

    The evolution of liquid inclusions which are formed in the hcp matrix by rapid cooling of the 3 He- 4 He solution containing 1.05% 3 He was studied by pulse NMR. The diffusion coefficient of 3 He in the liquid was measured by two-pulses spin-echo method during evolution of the inclusions. Measurements were carried out at 1.67 K which corresponds to the bcc phase existence in the phase diagram, as well as at 1.38 K, where the bcc phase is absent. It is found that in the process of the evolution, in both cases the size of the liquid inclusions is less than diffusion length and so the diffusion is restricted. The measured restricted dif-fusion coefficient allowed to find the characteristic size of the inclusions. In the first case, during the evolution of liquid inclusions, dendrites of intermediate bcc phase is forming and the inclusions are separating into a lot of smaller droplets. Due to the rapid growth of the bcc dendrites, the droplet size decreases rapidly, and the process comes to disappearance of bcc phase and an amorphous state appearance. The results obtained by measuring the diffusion coefficient, correlated with the behavior of the spin-lattice relaxation time in such a system. In the second case at a lower temperature bcc phase is not formed, and the size of the liquid inclusions decreases very slow until the completion of their solidification.

  6. Teaching Evolution in New Jersey Public High Schools: Examining the Influence of Personal Belief and Religious Background on Teaching Practices

    Science.gov (United States)

    Smith, Carlen

    2010-01-01

    The purpose of this study was to determine relationships between New Jersey biology teachers' personal characteristics and religious backgrounds and the time spent and approach to teaching evolution. The research instrument chosen was a cross-sectional survey. Survey questions were presented in various forms: fill in, single response, Likert…

  7. Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628

    Science.gov (United States)

    Adamo, A.; Ryon, J. E.; Messa, M.; Kim, H.; Grasha, K.; Cook, D. O.; Calzetti, D.; Lee, J. C.; Whitmore, B. C.; Elmegreen, B. G.; Ubeda, L.; Smith, L. J.; Bright, S. N.; Runnholm, A.; Andrews, J. E.; Fumagalli, M.; Gouliermis, D. A.; Kahre, L.; Nair, P.; Thilker, D.; Walterbos, R.; Wofford, A.; Aloisi, A.; Ashworth, G.; Brown, T. M.; Chandar, R.; Christian, C.; Cignoni, M.; Clayton, G. C.; Dale, D. A.; de Mink, S. E.; Dobbs, C.; Elmegreen, D. M.; Evans, A. S.; Gallagher, J. S., III; Grebel, E. K.; Herrero, A.; Hunter, D. A.; Johnson, K. E.; Kennicutt, R. C.; Krumholz, M. R.; Lennon, D.; Levay, K.; Martin, C.; Nota, A.; Östlin, G.; Pellerin, A.; Prieto, J.; Regan, M. W.; Sabbi, E.; Sacchi, E.; Schaerer, D.; Schiminovich, D.; Shabani, F.; Tosi, M.; Van Dyk, S. D.; Zackrisson, E.

    2017-06-01

    We report the large effort that is producing comprehensive high-level young star cluster (YSC) catalogs for a significant fraction of galaxies observed with the Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. We present the methodology developed to extract cluster positions, verify their genuine nature, produce multiband photometry (from NUV to NIR), and derive their physical properties via spectral energy distribution fitting analyses. We use the nearby spiral galaxy NGC 628 as a test case for demonstrating the impact that LEGUS will have on our understanding of the formation and evolution of YSCs and compact stellar associations within their host galaxy. Our analysis of the cluster luminosity function from the UV to the NIR finds a steepening at the bright end and at all wavelengths suggesting a dearth of luminous clusters. The cluster mass function of NGC 628 is consistent with a power-law distribution of slopes ˜ -2 and a truncation of a few times 105 {M}⊙ . After their formation, YSCs and compact associations follow different evolutionary paths. YSCs survive for a longer time frame, confirming their being potentially bound systems. Associations disappear on timescales comparable to hierarchically organized star-forming regions, suggesting that they are expanding systems. We find mass-independent cluster disruption in the inner region of NGC 628, while in the outer part of the galaxy there is little or no disruption. We observe faster disruption rates for low mass (≤104 {M}⊙ ) clusters, suggesting that a mass-dependent component is necessary to fully describe the YSC disruption process in NGC 628. Based on observations obtained with the NASA/ESA Hubble Space Telescope, at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  8. Anaerobic membrane bioreactors and the influence of space velocity and biomass concentration on methane production for liquid dairy manure

    International Nuclear Information System (INIS)

    Wallace, James M.; Safferman, Steven I.

    2014-01-01

    Two pilot-scale anaerobic membrane bioreactors (AnMBRs) and a control completely mixed digester (CMD) were constructed to evaluate the influence of space velocity and biomass concentration on methane production for sand separated dairy manure. A negative impact on methane production resulted with operating the AnMBR system at 972 μHz–2960 μHz but no impact was found when operating at 69 μHz and 312 μHz. Operating at 69 μHz–350 μHz is realistic for a field installation. Despite the higher biomass concentration, the methane production of the AnMBRs was nearly equal to the CMD. An AnMBR with 69 μHz was operated equivalent to a CMD by returning all permeate to the digester tank and removing excess biomass directly from the reactor tank resulting in a hydraulic retention time (HRT) equal to the solids retention time (SRT). When using sand separated dairy manure and an HRT (and equal SRT) of 12 d, both systems produced methane at an equal rate, suggesting that the pump/membrane system did not influence methane production. The most likely reason was mass transfer limitations of hydrolytic enzymes. Based on methane production and volatile fatty acids analysis, it appears the fermentable substrate available for degradation was similar. The AnMBR proved to have benefit as part of an integrated nutrient management system that produced water that is virtually free of particulate nutrients, especially phosphorus. This enables the irrigation of the water to crops that need nitrogen and the efficient movement of phosphorus, as a solid, to needed locations. - Highlights: • Manure AnMBRs with a high space velocity inhibit methane production. • Manure AnMBRs with a low space velocity perform similar to conventional digesters. • Decoupled HRT and SRT in manure AnMBRs do not increase methane production. • Ultrafiltration membranes effectively partitioned manure nutrients from the liquid. • Manure does not foul ultrafiltration membranes and require mild

  9. Evapotranspiration sensitivity to air temperature across a snow-influenced watershed: Space-for-time substitution versus integrated watershed modeling

    Science.gov (United States)

    Jepsen, S. M.; Harmon, T. C.; Ficklin, D. L.; Molotch, N. P.; Guan, B.

    2018-01-01

    Changes in long-term, montane actual evapotranspiration (ET) in response to climate change could impact future water supplies and forest species composition. For scenarios of atmospheric warming, predicted changes in long-term ET tend to differ between studies using space-for-time substitution (STS) models and integrated watershed models, and the influence of spatially varying factors on these differences is unclear. To examine this, we compared warming-induced (+2 to +6 °C) changes in ET simulated by an STS model and an integrated watershed model across zones of elevation, substrate available water capacity, and slope in the snow-influenced upper San Joaquin River watershed, Sierra Nevada, USA. We used the Soil Water and Assessment Tool (SWAT) for the watershed modeling and a Budyko-type relationship for the STS modeling. Spatially averaged increases in ET from the STS model increasingly surpassed those from the SWAT model in the higher elevation zones of the watershed, resulting in 2.3-2.6 times greater values from the STS model at the watershed scale. In sparse, deep colluvium or glacial soils on gentle slopes, the SWAT model produced ET increases exceeding those from the STS model. However, watershed areas associated with these conditions were too localized for SWAT to produce spatially averaged ET-gains comparable to the STS model. The SWAT model results nevertheless demonstrate that such soils on high-elevation, gentle slopes will form ET "hot spots" exhibiting disproportionately large increases in ET, and concomitant reductions in runoff yield, in response to warming. Predicted ET responses to warming from STS models and integrated watershed models may, in general, substantially differ (e.g., factor of 2-3) for snow-influenced watersheds exhibiting an elevational gradient in substrate water holding capacity and slope. Long-term water supplies in these settings may therefore be more resilient to warming than STS model predictions would suggest.

  10. Influence of the Reynolds number on the instant flow evolution of a turbulent rectangular free jet of air

    International Nuclear Information System (INIS)

    Gori, Fabio; Petracci, Ivano; Angelino, Matteo

    2014-01-01

    Highlights: • Flow with Negligible Disturbances, or first type, with length L ND = L 1 . • Flow with Small Disturbances, or second type, with length L SD . • Total length, L ND + L SD = L 2 , is in agreement with average Undisturbed flow, L U . • Flow with Coherent Vortices, or third type, with length L CV . • Total length, L ND + L SD + L CV = L 3 , is in agreement with average Potential core, L P . - Abstract: The paper is aimed at investigating the influence of the Reynolds number on the instant flow evolution of a rectangular free jet of air in the range of Reynolds numbers from Re = 35,300 to Re = 2,200, where the Reynolds number, Re, is defined according to the hydraulic diameter, D, of a rectangular slot of height H, equal to about D = 2H. The Particle Image Velocimetry (PIV) technique allows obtaining the instant PIV visualizations on the central symmetry section of the rectangular jet. The visual inspection of the instant frames with one and two vortices, except for Re = 35,300 where only one vortex images are detected, shows that after the jet exit is present the Flow with Constant Instant Height, with a length L CIH which increases with the decrease of the Reynolds number, from a ratio L CIH /H equal to L CIH /H = 0.9 at Re = 35,300 to L CIH /H = 4.0 at Re = 2,200. The instant PIV measurements, carried out at several distances from the jet exit, show that the variations of the ratio U/U ‾ 0 of the centerline instant velocity, U, to the exit average velocity, U ‾ 0 , remain below ±4% for a length L CIV , defining the Flow with Constant Instant Velocity on the centerline. The ratio L CIV /H increases from L CIV /H = 1.1 at Re = 35,300 to L CIV /H = 4.1 at Re = 2,200 and is quite similar to L CIH /H. The instant PIV measurements of the centerline turbulence intensity, Tu, show that its variations remain below ±4% for a length L CIT , defining the Flow with Constant Instant Turbulence on the centerline. The ratio L CIT /H is equal to L CIV /H

  11. Quasi-Linear Evolution of Trapped Electron Fluxes Under the Influence of Realistic Whistler-Mode Waves

    Science.gov (United States)

    Agapitov, O. V.; Mourenas, D.; Artemyev, A.; Krasnoselskikh, V.

    2014-12-01

    The evolution of fluxes of energetic trapped electrons as a function of geomagnetic activity is investigated using brand new statistical models of chorus waves derived from Cluster observations in the radiation belts. The new wave models provide the distributions of wave power and wave-normal angle with latitude as a function of either Dst or Kp indices. Lifetimes and energization of energetic electrons are examined, as well as the relevant uncertainties related to some of the wave models implicit assumptions.From the presented results, different implications concerning the characterization of relativistic flux enhancements and losses are provided.

  12. Influence of heat treatments on thermoelectric power of pressure vessel steels: effect of microstructural evolutions of strongly segregated areas

    International Nuclear Information System (INIS)

    Houze, M.

    2002-12-01

    Thermoelectric power measurement (TEP) is a very potential non destructive evaluation method considered to follow ageing under neutron irradiation of pressure vessel steel of nuclear reactor. Prior to these problems, the aim of this study is to establish correlations between TEP variations and microstructural evolutions of pressure vessel steels during heat treatments. Different steels, permitting to simulate heterogeneities of pressure vessel steels and to deconvoluate main metallurgical phenomenons effects were studied. This work allowed to emphasize effect on TEP of: austenitizing and cooling conditions and therefore of microstructure, metallurgical transformations during tempering (recovery, precipitation of alloying elements), and particularly molybdenum precipitation associated to secondary hardening, residual austenite amount or partial austenitizing. (author)

  13. An influence of ion and sputtered atom flows inhomogeneity on time evolution of the target surface relief in glow discharge

    International Nuclear Information System (INIS)

    Bondarenko, G G; Kristya, V I

    2008-01-01

    A mathematical model of ion and sputtered atom transport in the vicinity of the target with a periodical surface relief in glow discharge in pure gas is developed. Under the assumption that the relief amplitude is small, analytical expressions for their flows are found by the perturbation method and an equation describing the relief amplitude time evolution is derived. It is shown that intensity of sputtering exceeds intensity of sputtered material re-deposition at the relief tops, and relief smoothing always takes place in the process of homogeneous target treatment in glow discharge in pure gas

  14. Influence of system controls on the Late Quaternary geomorphic evolution of a rapidly-infilled incised-valley system: The lower Manawatu valley, North Island New Zealand

    Science.gov (United States)

    Clement, Alastair J. H.; Fuller, Ian C.

    2018-02-01

    The Manawatu incised-valley estuary was rapidly infilled between 12,000-4700 cal. yr BP. A combination of empirical measurements of sedimentation rates, a reconstruction of relative sea-level (RSL) change, and digital elevation models of key surfaces within the Holocene sedimentary fill of the valley were integrated to produce a numerical model to investigate the influence of the system controls of sea-level change, sediment flux, and accommodation space on the rapid infilling history of the palaeo-estuary. The numerical model indicates that sediment flux into the palaeo-estuary was greatest during the Holocene marine transgression between 12,000-8000 years BP. The average rate of sediment deposition in the estuary during this period was 1.0 M m3 yr- 1. This rapid rate of sedimentation was controlled by the rate of accommodation space creation, as regulated by the rate of sea-level rise and the antecedent configuration of the valley. By the time sea levels stabilised c. 7500 cal. yr BP, the palaeo-estuary had been substantively infilled. Limited accommodation space resulted in rapid infilling of the central basin, though sediment flux into the estuary between 7100 and 4500 cal. yr BP was at a lower rate of 234,000 m3 yr- 1. The limited accommodation space also influenced hydrodynamic conditions in the estuarine central basin, driving export of fine-grained sediment from the estuary. Once the accommodation space of the estuarine basin was infilled sediment bypassed the system, with a consequent reduction in the sedimentation rate in the valley. More accurate partitioning of the sources of sediment driving the infilling is necessary to quantify sediment bypassing. Post-depositional lowering of RSL index points from the valley is driven by neotectonics and sediment compaction.

  15. Influence of the laser parameters on the space and time characteristics of an aluminum laser-induced plasma

    International Nuclear Information System (INIS)

    Barthelemy, O.; Margot, J.; Chaker, M.; Sabsabi, M.; Vidal, F.; Johnston, T.W.; Laville, S.; Le Drogoff, B.

    2005-01-01

    In this work, an aluminum laser plasma produced in ambient air at atmospheric pressure by laser pulses at a fluence of 10 J/cm 2 is characterized by time- and space-resolved measurements of electron density and temperature. Varying the laser pulse duration from 6 ns to 80 fs and the laser wavelength from ultraviolet to infrared only slightly influences the plasma properties. The temperature exhibits a slight decrease both at the plasma edge and close to the target surface. The electron density is found to be spatially homogeneous in the ablation plume during the first microsecond. Finally, the plasma expansion is in good agreement with the Sedov's model during the first 500 ns and it becomes subsonic, with respect to the velocity of sound in air, typically 1 μs after the plasma creation. The physical interpretation of the experimental results is also discussed to the light of a one-dimensional fluid model which provides a good qualitative agreement with measurements

  16. Influence of two-stream relativistic electron beam parameters on the space-charge wave with broad frequency spectrum formation

    Science.gov (United States)

    Alexander, LYSENKO; Iurii, VOLK

    2018-03-01

    We developed a cubic non-linear theory describing the dynamics of the multiharmonic space-charge wave (SCW), with harmonics frequencies smaller than the two-stream instability critical frequency, with different relativistic electron beam (REB) parameters. The self-consistent differential equation system for multiharmonic SCW harmonic amplitudes was elaborated in a cubic non-linear approximation. This system considers plural three-wave parametric resonant interactions between wave harmonics and the two-stream instability effect. Different REB parameters such as the input angle with respect to focusing magnetic field, the average relativistic factor value, difference of partial relativistic factors, and plasma frequency of partial beams were investigated regarding their influence on the frequency spectrum width and multiharmonic SCW saturation levels. We suggested ways in which the multiharmonic SCW frequency spectrum widths could be increased in order to use them in multiharmonic two-stream superheterodyne free-electron lasers, with the main purpose of forming a powerful multiharmonic electromagnetic wave.

  17. VNI version 4.1. Simulation of high-energy particle collisions in QCD: Space-time evolution of e+e-... A + B collisions with parton-cascades, cluster-hadronization, final-state hadron cascades

    International Nuclear Information System (INIS)

    Geiger, K.; Longacre, R.

    1999-01-01

    VNI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. It uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme, as well as the development of hadron cascades after hadronization. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time-development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position-space, momentum-space and color-space. The parton-evolution is described in terms of a space-time generalization of the familiar momentum-space description of multiple (semi)hard interactions in QCD, involving 2 → 2 parton collisions, 2 → 1 parton fusion processes, and 1 → 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. Finally, the cascading of produced prehadronic clusters and of hadrons includes a multitude of 2 → n processes, and is modeled in parallel to the parton cascade description. This paper gives a brief review of the physics underlying VNI, as well as a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including simple examples), annotates input and control parameters, and discusses output data provided by it

  18. VNI 3.1 MC-simulation program to study high-energy particle collisions in QCD by space-time evolution of parton-cascades and parton-hadron conversion

    Science.gov (United States)

    Geiger, Klaus

    1997-08-01

    VNI is a general-purpose Monte Carlo event generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. On the basis of renormalization-group improved parton description and quantum-kinetic theory, it uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme that is governed by the dynamics itself. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position space, momentum space and color space. The parton evolution is described in terms of a space-time generalization of the familiar momentum-space description of multiple (semi) hard interactions in QCD, involving 2 → 2 parton collisions, 2 → 1 parton fusion processes, and 1 → 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. This article gives a brief review of the physics underlying VNI, which is followed by a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including a simple example), annotates input and control parameters, and discusses output data provided by it.

  19. The influence of iridium chemical oxidation state on the performance and durability of oxygen evolution catalysts in PEM electrolysis

    Science.gov (United States)

    Siracusano, S.; Baglio, V.; Grigoriev, S. A.; Merlo, L.; Fateev, V. N.; Aricò, A. S.

    2017-10-01

    Nanosized Ir-black (3 nm) and Ir-oxide (5 nm) oxygen evolution electrocatalysts showing high performance in polymer electrolyte membrane (PEM) water electrolysis based on Aquivion® short-side chain ionomer membrane are investigated to understand the role of the Ir oxidation state on the electrocatalytic activity and stability. Despite the smaller mean crystallite size, the Ir-black electrocatalyst shows significantly lower initial performance than the Ir-oxide. During operation at high current density, the Ir-black shows a decrease of cell potential with time whereas the Ir-oxide catalyst shows increasing cell potential resulting in a degradation rate of about 10 μV/h, approaching 1000 h. The unusual behaviour of the Ir-black results from the oxidation of metallic Ir to IrOx. The Ir-oxide catalyst shows instead a hydrated structure on the surface and a negative shift of about 0.5 eV for the Ir 4f binding energy after 1000 h electrolysis operation. This corresponds to the formation of a sub-stoichiometric Ir-oxide on the surface. These results indicate that a hydrated IrO2 with high oxidation state on the surface is favourable in decreasing the oxygen evolution overpotential. Modifications of the Ir chemical oxidation state during operation can affect significantly the catalytic activity and durability of the electrolysis system.

  20. Competitive fitness during feast and famine: how SOS DNA polymerases influence physiology and evolution in Escherichia coli.

    Science.gov (United States)

    Corzett, Christopher H; Goodman, Myron F; Finkel, Steven E

    2013-06-01

    Escherichia coli DNA polymerases (Pol) II, IV, and V serve dual roles by facilitating efficient translesion DNA synthesis while simultaneously introducing genetic variation that can promote adaptive evolution. Here we show that these alternative polymerases are induced as cells transition from exponential to long-term stationary-phase growth in the absence of induction of the SOS regulon by external agents that damage DNA. By monitoring the relative fitness of isogenic mutant strains expressing only one alternative polymerase over time, spanning hours to weeks, we establish distinct growth phase-dependent hierarchies of polymerase mutant strain competitiveness. Pol II confers a significant physiological advantage by facilitating efficient replication and creating genetic diversity during periods of rapid growth. Pol IV and Pol V make the largest contributions to evolutionary fitness during long-term stationary phase. Consistent with their roles providing both a physiological and an adaptive advantage during stationary phase, the expression patterns of all three SOS polymerases change during the transition from log phase to long-term stationary phase. Compared to the alternative polymerases, Pol III transcription dominates during mid-exponential phase; however, its abundance decreases to SOS induction by exogenous agents and indicate that cell populations require appropriate expression of all three alternative DNA polymerases during exponential, stationary, and long-term stationary phases to attain optimal fitness and undergo adaptive evolution.

  1. Adaptive evolution influences the infectious dose of MERS-CoV necessary to achieve severe respiratory disease.

    Science.gov (United States)

    Douglas, Madeline G; Kocher, Jacob F; Scobey, Trevor; Baric, Ralph S; Cockrell, Adam S

    2018-04-01

    We recently established a mouse model (288-330 +/+ ) that developed acute respiratory disease resembling human pathology following infection with a high dose (5 × 10 6 PFU) of mouse-adapted MERS-CoV (icMERSma1). Although this high dose conferred fatal respiratory disease in mice, achieving similar pathology at lower viral doses may more closely reflect naturally acquired infections. Through continued adaptive evolution of icMERSma1 we generated a novel mouse-adapted MERS-CoV (maM35c4) capable of achieving severe respiratory disease at doses between 10 3 and 10 5 PFU. Novel mutations were identified in the maM35c4 genome that may be responsible for eliciting etiologies of acute respiratory distress syndrome at 10-1000 fold lower viral doses. Importantly, comparative genetics of the two mouse-adapted MERS strains allowed us to identify specific mutations that remained fixed through an additional 20 cycles of adaptive evolution. Our data indicate that the extent of MERS-CoV adaptation determines the minimal infectious dose required to achieve severe respiratory disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Special Features in the Structure of Resonant Perturbations of Uncontrollable Objects of Glonass and GPS Navigating Systems. Influence on the Orbital Evolution

    Science.gov (United States)

    Tomilova, I. V.; Bordovitsyna, T. V.

    2017-08-01

    Results of investigation into the resonant structure of perturbations and long-term orbital evolution of space vehicles of GLONASS and GPS global navigating satellite systems (GNSS) under assumption that all of them have lost control on 08/01/2015 are presented. It is demonstrated that the majority of the examined objects are in the range of action of the secular resonances of various types. In addition, practically all satellites of the GPS system are within the scope of the 2:1 orbital resonance with rotation of the Earth. Results of the MEGNO analysis demonstrate that the motion of all objects of the GLONASS system during the 100-year period is regular, whereas the motion of the majority of objects of the GPS system is subject to chaotization.

  3. Evolution of Fe based intermetallic phases in Al–Si hypoeutectic casting alloys: Influence of the Si and Fe concentrations, and solidification rate

    International Nuclear Information System (INIS)

    Gorny, Anton; Manickaraj, Jeyakumar; Cai, Zhonghou; Shankar, Sumanth

    2013-01-01

    Highlights: •Anomalous evolution of Fe based intermetallic phases in Al–Si–Fe alloys. •XRF coupled with nano-diffraction to confirm the nano-size Fe intermetallic phases. •Crystallography of the θ-Al 13 Fe 4 , τ 5 -Al 8 Fe 2 Si and τ 6 -Al 9 Fe 2 Si 2 phases. •Peritectic reactions involving the Fe intermetallic phases in Al–Si–Fe alloys. -- Abstract: Al–Si–Fe hypoeutectic cast alloy system is very complex and reported to produce numerous Fe based intermetallic phases in conjunction with Al and Si. This publication will address the anomalies of phase evolution in the Al–Si–Fe hypoeutectic casting alloy system; the anomaly lies in the peculiarities in the evolution and nature of the intermetallic phases when compared to the thermodynamic phase diagram predictions and past publications of the same. The influence of the following parameters, in various combinations, on the evolution and nature of the intermetallic phases were analyzed and reported: concentration of Si between 2 and 12.6 wt%, Fe between 0.05 and 0.5 wt% and solidification rates of 0.1, 1, 5 and 50 K s −1 . Two intermetallic phases are observed to evolve in these alloys under these solidification conditions: the τ 5 -Al 8 SiFe 2 and τ 6 -Al 9 Fe 2 Si 2 . The τ 5 -Al 8 SiFe 2 phase evolves at all levels of the parameters during solidification and subsequently transforms into the τ 6 -Al 9 Fe 2 Si 2 through a peritectic reaction when promoted by certain combinations of solidification parameters such as higher Fe level, lower Si level and slower solidification rates. Further, it is also hypothesized from experimental evidences that the θ-Al 13 Fe 4 binary phase precludes the evolution of the τ 5 during solidification and subsequently transforms into the τ 6 phase during solidification. These observations are anomalous to the publications as prior art and simulation predictions of thermodynamic phase diagrams of these alloys, wherein, only one intermetallic phases in the

  4. Influence of sweeping detonation-wave loading on damage evolution during spallation loading of tantalum in both a planar and curved geometry

    Energy Technology Data Exchange (ETDEWEB)

    Gray, George Thompson III [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hull, Lawrence Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Livescu, Veronica [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Faulkner, James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Briggs, Matthew E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meyer, Ross Keith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Andrews, Heather Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hare, Steven John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jakulewicz, Micah Shawn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shinas, Michael A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-30

    Widespread research over the past five decades has provided a wealth of experimental data and insight concerning the shock hardening, damage evolution, and the spallation response of materials subjected to square-topped shock-wave loading profiles. However, fewer quantitative studies have been conducted on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (unsupported shocks) loading on the shock hardening, damage evolution, or spallation response of materials. Systematic studies quantifying the effect of sweeping-detonation wave loading are yet sparser. In this study, the damage evolution and spallation response of Ta is shown to be critically dependent on the peak shock stress, the geometry of the sample (flat or curved plate geometry), and the shock obliquity during sweeping-detonation-wave shock loading. Sweepingwave loading in the flat-plate geometry is observed to: a) yield a lower spall strength than previously documented for 1-D supported-shock-wave loading, b) exhibit increased shock hardening as a function of increasing obliquity, and c) lead to an increased incidence of deformation twin formation with increasing shock obliquity. Sweeping-wave loading of a 10 cm radius curved Ta plate is observed to: a) lead to an increase in the shear stress as a function of increasing obliquity, b) display a more developed level of damage evolution, extensive voids and coalescence, and lower spall strength with obliquity in the curved plate than seen in the flat-plate sweeping-detonation wave loading for an equivalent HE loading, and c) no increased propensity for deformation twin formation with increasing obliquity as seen in the flat-plate geometry. The overall observations comparing and contrasting the flat versus curved sweeping-wave spall experiments with 1D loaded spallation behavior suggests a coupled influence of obliquity and geometry on dynamic shock-induced damage evolution and spall strength. Coupled experimental and modeling research

  5. The Dynamic Family Home: a qualitative exploration of physical environmental influences on children's sedentary behaviour and physical activity within the home space.

    Science.gov (United States)

    Maitland, Clover; Stratton, Gareth; Foster, Sarah; Braham, Rebecca; Rosenberg, Michael

    2014-12-24

    Recent changes in home physical environments, such as decreasing outdoor space and increasing electronic media, may negatively affect health by facilitating sedentariness and reducing physical activity. As children spend much of their time at home they are particularly vulnerable. This study qualitatively explored family perceptions of physical environmental influences on sedentary behaviour and physical activity within the home space. Home based interviews were conducted with 28 families with children aged 9-13 years (total n = 74 individuals), living in Perth, Australia. Families were stratified by socioeconomic status and selected to provide variation in housing. Qualitative methods included a family interview, observation and home tour where families guided the researcher through their home, enabling discussion while in the physical home space. Audio recordings were transcribed verbatim and thematically analysed. Emergent themes related to children's sedentariness and physical activity included overall size, space and design of the home; allocation of home space; equipment within the home space; perceived safety of the home space; and the changing nature of the home space. Families reported that children's activity options were limited when houses and yards were small. In larger homes, multiple indoor living rooms usually housed additional sedentary entertainment options, although parents reported that open plan home layouts could facilitate monitoring of children's electronic media use. Most families reported changing the allocation and contents of their home space in response to changing priorities and circumstances. The physical home environment can enhance or limit opportunities for children's sedentary behaviour and physical activity. However, the home space is a dynamic ecological setting that is amenable to change and is largely shaped by the family living within it, thus differentiating it from other settings. While size and space were considered

  6. Microstructural evolution of Au/TiO{sub 2} nanocomposite films: The influence of Au concentration and thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Borges, J., E-mail: joelborges@fisica.uminho.pt [Instituto Pedro Nunes, Laboratório de Ensaios, Desgaste e Materiais, Rua Pedro Nunes, 3030-199 Coimbra (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Kubart, T.; Kumar, S.; Leifer, K. [Solid-State Electronics, Department of Engineering Sciences, Uppsala University, P.O. Box 534, Uppsala SE-751 21 (Sweden); Rodrigues, M.S. [Instituto Pedro Nunes, Laboratório de Ensaios, Desgaste e Materiais, Rua Pedro Nunes, 3030-199 Coimbra (Portugal); Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Duarte, N.; Martins, B.; Dias, J.P. [Instituto Pedro Nunes, Laboratório de Ensaios, Desgaste e Materiais, Rua Pedro Nunes, 3030-199 Coimbra (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Vaz, F. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2015-04-01

    Nanocomposite thin films consisting of a dielectric matrix, such as titanium oxide (TiO{sub 2}), with embedded gold (Au) nanoparticles were prepared and will be analysed and discussed in detail in the present work. The evolution of morphological and structural features was studied for a wide range of Au concentrations and for annealing treatments in air, for temperatures ranging from 200 to 800 °C. Major findings revealed that for low Au atomic concentrations (at.%), there are only traces of clustering, and just for relatively high annealing temperatures, T ≥ 500 °C. Furthermore, the number of Au nanoparticles is extremely low, even for the highest annealing temperature, T = 800 °C. It is noteworthy that the TiO{sub 2} matrix also crystallizes in the anatase phase for annealing temperatures above 300 °C. For intermediate Au contents (5 at.% ≤ C{sub Au} ≤ 15 at.%), the formation of gold nanoclusters was much more evident, beginning at lower annealing temperatures (T ≥ 200 °C) with sizes ranging from 2 to 25 nm as the temperature increased. A change in the matrix crystallization from anatase to rutile was also observed in this intermediate range of compositions. For the highest Au concentrations (> 20 at.%), the films tended to form relatively larger clusters, with sizes above 20 nm (for T ≥ 400 °C). It is demonstrated that the structural and morphological characteristics of the films are strongly affected by the annealing temperature, as well as by the particular amounts, size and distribution of the Au nanoparticles dispersed in the TiO{sub 2} matrix. - Highlights: • Au:TiO{sub 2} films were produced by magnetron sputtering and post-deposition annealing. • The Au concentration in the films increases with the Au pellet area. • Annealing induced microstructural changes in the films. • The nanoparticle size evolution with temperature depends on the Au concentration.

  7. The influence of anthropic actions on the evolution of an urban beach: Case study of Marineta Cassiana beach, Spain.

    Science.gov (United States)

    Pagán, J I; Aragonés, L; Tenza-Abril, A J; Pallarés, P

    2016-07-15

    Coastal areas have been historically characterized as being a source of wealth. Nowadays, beaches have become more relevant as a place for rest and leisure. This had led to a very high population pressure due to rapid urbanisation processes. The impacts associated with coastal tourism, demand the development of anthropic actions to protect the shoreline. This paper has studied the impacts of these actions on the Marineta Cassiana beach, in Denia, Spain. This particular Mediterranean beach has traditionally suffered a major shoreline regression, and the beach nourishments carried out in the 1980s would not have achieved the reliability desired. This research has analysed the historic evolution of the beach and its environment for a period of 65years (1950-2015). A Geographic Information System (GIS) has been used to integrate and perform a spatial analysis of urban development, soil erosion, stream flow, swell, longshore transport, submerged vegetation species and shoreline evolution. The results show how the anthropic actions have affected the shoreline. After the excessive urban development of the catchments, there is no natural sediment supply to the beach. The change in the typology of the sediment, from pebbles to sand, during the beach nourishments has led to a crucial imbalance in the studied area. Moreover, the beach area gained has disappeared, affecting the Posidonia oceanica meadow, and incrementing the erosion rates. The findings obtained are relevant, not only in the management and maintenance of the beaches, but also, in the decision-making for future nourishments. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Development of equations to predict the influence of floor space on average daily gain, average daily feed intake and gain : feed ratio of finishing pigs.

    Science.gov (United States)

    Flohr, J R; Dritz, S S; Tokach, M D; Woodworth, J C; DeRouchey, J M; Goodband, R D

    2018-05-01

    Floor space allowance for pigs has substantial effects on pig growth and welfare. Data from 30 papers examining the influence of floor space allowance on the growth of finishing pigs was used in a meta-analysis to develop alternative prediction equations for average daily gain (ADG), average daily feed intake (ADFI) and gain : feed ratio (G : F). Treatment means were compiled in a database that contained 30 papers for ADG and 28 papers for ADFI and G : F. The predictor variables evaluated were floor space (m2/pig), k (floor space/final BW0.67), Initial BW, Final BW, feed space (pigs per feeder hole), water space (pigs per waterer), group size (pigs per pen), gender, floor type and study length (d). Multivariable general linear mixed model regression equations were used. Floor space treatments within each experiment were the observational and experimental unit. The optimum equations to predict ADG, ADFI and G : F were: ADG, g=337.57+(16 468×k)-(237 350×k 2)-(3.1209×initial BW (kg))+(2.569×final BW (kg))+(71.6918×k×initial BW (kg)); ADFI, g=833.41+(24 785×k)-(388 998×k 2)-(3.0027×initial BW (kg))+(11.246×final BW (kg))+(187.61×k×initial BW (kg)); G : F=predicted ADG/predicted ADFI. Overall, the meta-analysis indicates that BW is an important predictor of ADG and ADFI even after computing the constant coefficient k, which utilizes final BW in its calculation. This suggests including initial and final BW improves the prediction over using k as a predictor alone. In addition, the analysis also indicated that G : F of finishing pigs is influenced by floor space allowance, whereas individual studies have concluded variable results.

  9. Texture evolution in Nd:YAG-laser welds of AZ31 magnesium alloy hot rolled sheets and its influence on mechanical properties

    International Nuclear Information System (INIS)

    Commin, Lorelei; Dumont, Myriam; Rotinat, Rene; Pierron, Fabrice; Masse, Jean-Eric; Barrallier, Laurent

    2011-01-01

    Research highlights: → AZ31 LBW fusion zone results in Mg 17 (Al-Zn) 12 precipitation, twins formation and {0 0 2} texture modification. → The mechanical properties were reduced after LBW but the fracture occurred in the base metal. → The mechanical properties were reduced after LBW but the fracture occurred in the base metal. → A recovery of elongation and UTS can be achieved by a 300 deg. C/1 h heat treatment. The texture evolution is mainly responsible for the yield strength reduction in the fusion zone. - Abstract: AZ31 hot rolled magnesium alloy presents a strong basal texture. Using laser beam welding (LBW) as a joining process induces high temperature gradients leading to major texture changes. Electron back scattered diffraction (EBSD) was used to study the texture evolution, and tensile tests coupled with speckle interferometry were performed to understand its influence on mechanical properties. The random texture obtained in the LBW fusion zone is mainly responsible for the yield strength reduction.

  10. The influence of plant spacing in the early stages of selection of rice (Oryza sativa L.) varieties

    Energy Technology Data Exchange (ETDEWEB)

    Torró, I.; Bretó, P.; García-Yzaguirre, A.

    2016-11-01

    The cultural practices of the early generations in a pedigree breeding programme may influence its success. The main objective of this study was to compare two selection environments in rice: Widely spaced planting in the field and dense planting in concrete basins. Both methods had yielded commercial varieties in the past. Two F2 populations (J and MS), derived from two crosses sharing the same female parent, were transplanted to both environments. Phenotypic traits were evaluated and their narrow sense heritabilities (h2) estimated in the F3 and in the F4 progenies of selected plants, all grown in the field. Growth potential was more apparent in the field for most traits, especially those related to yield, but broad sense heritabilities were higher in the basins for ten traits, being higher in the field for the other five. In population F2MS, field selection resulted in F3 plants which retained a higher tillering ability than those derived from basins selection. Most traits showed low h2 values: Additive variance was only relevant in panicle length (in both populations), plant height and mean panicle weight (in the J population). However, response to one generation of selection (from F3 to F4) also showed fixable variation in panicle number. In addition, this selection reduced plant height, increased culm diameter and internode length (in both populations), and improved pulling resistance (against lodging) in population J. It may be concluded that both practices can be used for selection in the F2, although different responses might be expected in yield related traits. (Author)

  11. Gossip Consensus Algorithm Based on Time-Varying Influence Factors and Weakly Connected Graph for Opinion Evolution in Social Networks

    Directory of Open Access Journals (Sweden)

    Lingyun Li

    2013-01-01

    Full Text Available We provide a new gossip algorithm to investigate the problem of opinion consensus with the time-varying influence factors and weakly connected graph among multiple agents. What is more, we discuss not only the effect of the time-varying factors and the randomized topological structure but also the spread of misinformation and communication constrains described by probabilistic quantized communication in the social network. Under the underlying weakly connected graph, we first denote that all opinion states converge to a stochastic consensus almost surely; that is, our algorithm indeed achieves the consensus with probability one. Furthermore, our results show that the mean of all the opinion states converges to the average of the initial states when time-varying influence factors satisfy some conditions. Finally, we give a result about the square mean error between the dynamic opinion states and the benchmark without quantized communication.

  12. Space Station fluid management logistics

    Science.gov (United States)

    Dominick, Sam M.

    1990-01-01

    Viewgraphs and discussion on space station fluid management logistics are presented. Topics covered include: fluid management logistics - issues for Space Station Freedom evolution; current fluid logistics approach; evolution of Space Station Freedom fluid resupply; launch vehicle evolution; ELV logistics system approach; logistics carrier configuration; expendable fluid/propellant carrier description; fluid carrier design concept; logistics carrier orbital operations; carrier operations at space station; summary/status of orbital fluid transfer techniques; Soviet progress tanker system; and Soviet propellant resupply system observations.

  13. Influence of the Mo and W additions on the microstructure evolution and mechanical properties in Si-Cr spring steels

    International Nuclear Information System (INIS)

    Ban, Deok Young; Lee, Sang Lae; Nam, Won Jong

    1998-01-01

    Effects of the Mo and W additions to Si-Cr spring steels on the microstructural evolution and mechanical properties in spring steels were investigated. It was found that the Mo and/or W addition does not change the behavior of tempered carbide at low temperatures, such as the precipitation of ε-carbide and the conversion of ε-carbide to cementite, via dilatometry tests and the observation of microstructure using TEM. However, it would reduce the coarsening rate of cementite at high temperature above 450 .deg. C, resulting in the smaller size of cementite particles due to the lower diffusion rate. Since the sag resistance depends on the distribution and the size of precipitates, steel C(0.2% W) showed the strongest sag resistance whereas steel A showed the weakest sag resistance, when tempered at 450 .deg. C. Also, an abundance of precipitates at 350 deg. C tempering exhibits the maximum loop area, i.e., the sag resistance for all the tested steels. The Mo and W additions to Si-Cr spring steels raised the ratio of loop area/tensile strength. Therefore, the Mo and W additions would be effective method to increase the sag resistance as well as strength in Si-Cr spring steels

  14. Influence of a stellar wind on the evolution of a star of 30 M/sub sun/

    International Nuclear Information System (INIS)

    Stothers, R.; Chin, C.

    1980-01-01

    A coarse grid of theoretical evolutionary tracks has been computed for a star of 30 M/sub sun/, in an attempt to delineate the role of mass loss in the star's evolution during core helium burning. For all of the tracks, Cox-Stewart opacities have been adopted, and the free parameters have included the rate of mass loss, criterion for convection, and initial chemical composition. With the use of the Schwarzschild criterion, the star suffers little mass loss during core helium burning and remains almost to the end, a blue supergiant, well separated from main-sequence stars on the H-R diagram. With the use of the Ledoux criterion, the same consequences are obtained only in the case of a relatively low initial hydrogen or initial metals abundance. Otherwise, the star evolves, first, into a red supergiant, whereupon rapid mass loss must be assumed to take place, if the observed paucity of very bright red supergiants is to be accounted for. The stellar remnant then consists of little more than the original helium core, and may appear, for a time, bluer than equally luminous main-sequence stars, provided that the the initial hydrogen and metals abundances are normal. Thus, a wide variety of possible evolutionary tracks can be obtained for an initial mass of 30 M/sub sun/ with reasonable choices of the free parameters

  15. The influence of Anglo-American theoretical models on the evolution of the nursing discipline in Spain.

    Science.gov (United States)

    Rodrigo, Olga; Caïs, Jordi; Monforte-Royo, Cristina

    2017-07-01

    In Spain, the introduction of the new Diploma in Nursing in 1977 saw the role of nurses shifting from that of medical assistants with technical skills to being independent members of the healthcare team with specific responsibility for providing professional nursing care. Here, we analyse the evolution of the nursing profession in Spain following the transfer of nurse education to universities, doing so through interviews with the first generation of academic tutors. This was a qualitative study using the method of analytic induction and based on the principles of grounded theory. Participants were selected by means of theoretical sampling and then underwent in-depth interviews. Steps were taken to ensure the credibility, transferability, dependability and confirmability of data. The main conclusion of the analysis is that there is a gap between a theoretical framework borrowed from the Anglo-American context and a nursing practice that, in Spain, has traditionally prioritised the application of technical procedures, a role akin to that of a medical assistant. It is argued that a key factor underlying the way in which nursing in Spain has evolved in recent decades is the lack of conceptual clarity regarding what the role of the professional nurse might actually entail in practice. © 2016 John Wiley & Sons Ltd.

  16. The influence of peak stress on the mechanical behavior and the substructural evolution in shock-prestrained zirconium

    International Nuclear Information System (INIS)

    Cerreta, E.; Gray, G.T. III; Henrie, B.L.; Brown, D.W.; Hixson, R.S.; Rigg, P.A.

    2004-01-01

    The post shock mechanical behavior and substructure evolution of zirconium (Zr) under shock prestrained at 5.8 and 8 GPa, above and below the pressure induced α-ω phase transition, has been quantified. The reload yield stress of Zr shock prestrained to 8 GPa was found to exhibit enhanced shock hardening when compared to the flow stress measured quasi-statically at an equivalent strain. In contrast, the reload yield behavior of Zr specimens shocked to 5.8 GPa did not exhibit enhanced shock hardening. The microstructure of the as-annealed and shock prestrained materials were examined. The presence of a reduced available glide distance due to a relatively more well developed dislocation substructure and increased twinning over quasi-static specimens deformed to comparable strains correlates with the increased yield stresses after shock prestraining at 8 GPa. Additionally, the retention of ∼ 40% by volume metastable high-pressure ω-phase in specimens shocked to 8 GPa and its absence in the 5.8 GPa specimen, is thought to contribute to the increased yield stress in the 8 GPa specimens

  17. An Opportunity for Reflection – A Special Issue on “The Constitution of Canada: History, Evolution, Influence and Reform”

    Directory of Open Access Journals (Sweden)

    Martinico Giuseppe

    2017-12-01

    Full Text Available Canada is and will for the foreseeable future be a peaceful and prosperous liberal democracy whose Constitution Act, 1867, now 150 years old as of 2017, has become a model for the modern world. The Constitution of Canada has exerted considerable influence on other countries, particularly since the coming into force of its Constitution Act, 1982, which included the celebrated Canadian Charter of Rights and Freedoms. Just as Canada drew from foreign and international experiences in drafting its Charter, the world has learned a great deal from Canada, not only as to rights protections but also as to the separation of powers, the judicial function, and the structure of government.

  18. Microstructural evolutions in warm compression of Betacez and 6246 titanium alloys and influence of the forging on the transformation {beta} {yields} {alpha}; Evolutions microstructurales en compression a chaud des alliages de titane Betacez et 6246 et influence du forgeage sur la transformation {beta} {yields} {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Chaussy Mraizika, F

    1996-06-26

    The relations between the thermomechanical ranges and the microstructures of titanium alloys are still insufficient. This work proposes to improve the knowledge of structural state coming from the {beta} forging and the ulterior transformation {beta} to {alpha}+{beta}. The influence of the two parameters, rate and strain speed, on the microstructural and textural evolutions appear during the forging and also during the {beta}/{alpha} transformation are systematically studied. The two titanium alloys which are studied are Betacez titanium alloy and the 6246 titanium alloy. (N.C.)

  19. Small Boreal Lake Ecosystem Evolution under the Influence of Natural and Anthropogenic Factors: Results of Multidisciplinary Long-Term Study

    Directory of Open Access Journals (Sweden)

    Liudmila Shirokova

    2016-07-01

    Full Text Available Small aquatic ecosystems of the boreal zone are known to be most sensitive indicators of on-going environmental change as well as local anthropogenic pressure, while being highly vulnerable to external impacts. Compared to rather detailed knowledge of the evolution of large and small lakes in Scandinavia and Canada, and large lakes in Eurasia, highly abundant small boreal lakes of northwest Russia have received very little attention, although they may become important centers of attraction of growing rural population in the near future. Here we present the results of a multidisciplinary, multi-annual study of a small boreal humic lake of NW Russia. A shallow (3 m and a deep (16 m site of this lake were regularly sampled for a range of chemical and biological parameters. Average multi-daily, summer-time values of the epilimnion (upper oxygenated layer of the lake provided indications of possible trends in temperature, nutrients, and bacterio-plankton concentration that revealed the local pollution impact in the shallow zone and overall environmental trend in the deep sampling point of the lake. Organic phosphorus, nitrate, and lead were found to be most efficient tracers of local anthropogenic pollution, especially visible in the surface layer of the shallow site of the lake. Cycling of trace elements between the epilimnion and hypolimnion is tightly linked to dissolved organic matter speciation and size fractionation due to the dominance of organic and organo-ferric colloids. The capacity of lake self-purification depends on the ratio of primary productivity to mineralization of organic matter. This ratio remained >1 both during winter and summer periods, which suggests a high potential of lake recovery from the input of allochthonous dissolved organic matter and local anthropogenic pollution.

  20. Influence of the substrate on the morphological evolution of gold thin films during solid-state dewetting

    International Nuclear Information System (INIS)

    Nsimama, Patrick D.; Herz, Andreas; Wang, Dong; Schaaf, Peter

    2016-01-01

    Highlights: • Dewetting of thin gold films is faster on TiO_2 than on SiO_2. • Dewetting of thin gold films is faster on amorphous TiO_2 than on crystalline TiO_2. • The kinetics is attributed to the energy of adhesion. • The morphology of thin Au films deposited on TiO_2 substrates is different to those deposited on SiO_2 substrates. • The dewetting activation energy of Au films deposited on crystalline substrates was higher than the activation energy of Au nanofilms deposited on amorphous TiO_2 substrates. - Abstract: The evolution of electron-beam evaporated Au thin films deposited on crystalline TiO_2 (c-TiO_2) and amorphous TiO_2 (a-TiO_2) as well as amorphous SiO_2 substrates are investigated. The kinetic of dewetting is clearly dependent on the type of substrate and is faster on TiO_2 substrates than on SiO_2 substrates. This difference can result from the difference in adhesion energy. Furthermore, the kinetic of dewetting is faster on a-TiO_2 than on c-TiO_2, possibly due to the crystallization of TiO_2 during annealing induced dewetting process. The morphologies of dewetted Au films deposited on crystalline TiO_2 are characterized by branched holes. The XRD patterns of the Au films deposited on TiO_2 substrates constituted peaks from both metallic Au and anatase TiO_2. The activation energy of Au films deposited on crystalline TiO_2 substrates was higher than that that of the films deposited on amorphous TiO_2 substrates.

  1. Influence of the substrate on the morphological evolution of gold thin films during solid-state dewetting

    Energy Technology Data Exchange (ETDEWEB)

    Nsimama, Patrick D. [TU Ilmenau, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, Chair Materials for Electrical Engineering and Electronics, 98693 Ilmenau (Germany); Dar Es Salaam Institute of Technology, P.O. Box 2958, Dar Es Salaam (Tanzania, United Republic of); Herz, Andreas; Wang, Dong [TU Ilmenau, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, Chair Materials for Electrical Engineering and Electronics, 98693 Ilmenau (Germany); Schaaf, Peter, E-mail: peter.schaaf@tu-ilmenau.de [TU Ilmenau, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, Chair Materials for Electrical Engineering and Electronics, 98693 Ilmenau (Germany)

    2016-12-01

    Highlights: • Dewetting of thin gold films is faster on TiO{sub 2} than on SiO{sub 2}. • Dewetting of thin gold films is faster on amorphous TiO{sub 2} than on crystalline TiO{sub 2}. • The kinetics is attributed to the energy of adhesion. • The morphology of thin Au films deposited on TiO{sub 2} substrates is different to those deposited on SiO{sub 2} substrates. • The dewetting activation energy of Au films deposited on crystalline substrates was higher than the activation energy of Au nanofilms deposited on amorphous TiO{sub 2} substrates. - Abstract: The evolution of electron-beam evaporated Au thin films deposited on crystalline TiO{sub 2} (c-TiO{sub 2}) and amorphous TiO{sub 2} (a-TiO{sub 2}) as well as amorphous SiO{sub 2} substrates are investigated. The kinetic of dewetting is clearly dependent on the type of substrate and is faster on TiO{sub 2} substrates than on SiO{sub 2} substrates. This difference can result from the difference in adhesion energy. Furthermore, the kinetic of dewetting is faster on a-TiO{sub 2} than on c-TiO{sub 2}, possibly due to the crystallization of TiO{sub 2} during annealing induced dewetting process. The morphologies of dewetted Au films deposited on crystalline TiO{sub 2} are characterized by branched holes. The XRD patterns of the Au films deposited on TiO{sub 2} substrates constituted peaks from both metallic Au and anatase TiO{sub 2}. The activation energy of Au films deposited on crystalline TiO{sub 2} substrates was higher than that that of the films deposited on amorphous TiO{sub 2} substrates.

  2. Bond Coat Engineering Influence on the Evolution of the Microstructure, Bond Strength, and Failure of TBCs Subjected to Thermal Cycling

    Science.gov (United States)

    Lima, R. S.; Nagy, D.; Marple, B. R.

    2015-01-01

    Different types of thermal spray systems, including HVOF (JP5000 and DJ2600-hybrid), APS (F4-MB and Axial III), and LPPS (Oerlikon Metco system) were employed to spray CoNiCrAlY bond coats (BCs) onto Inconel 625 substrates. The chemical composition of the BC powder was the same in all cases; however, the particle size distribution of the powder employed with each torch was that specifically recommended for the torch. For optimization purposes, these BCs were screened based on initial evaluations of roughness, porosity, residual stress, relative oxidation, and isothermal TGO growth. A single type of standard YSZ top coat was deposited via APS (F4MB) on all the optimized BCs. The TBCs were thermally cycled by employing a furnace cycle test (FCT) (1080 °C-1 h—followed by forced air cooling). Samples were submitted to 10, 100, 400, and 1400 cycles as well as being cycled to failure. The behavior of the microstructures, bond strength values (ASTM 633), and the TGO evolution of these TBCs, were investigated for the as-sprayed and thermally cycled samples. During FCT, the TBCs found to be both the best and poorest performing and had their BCs deposited via HVOF. The results showed that engineering low-oxidized BCs does not necessarily lead to an optimal TBC performance. Moreover, the bond strength values decrease significantly only when the TBC is about to fail (top coat spall off) and the as-sprayed bond strength values cannot be used as an indicator of TBC performance.

  3. Influence of the nutritional status in the clinical and therapeutical evolution in adults and elderly with American Tegumentary Leishmaniasis.

    Science.gov (United States)

    Oliveira, A G L; Brito, P D; Schubach, A O; Oliveira, R V C; Saheki, M N; Lyra, M R; Salgueiro, M M; Terceiro, B F; Pimentel, M I F; Vasconcellos, E C; Valete-Rosalino, C M

    2013-10-01

    The objective of this study is to describe the nutritional status of adult and elderly patients with American Tegumentary Leishmaniasis (ATL). It was conducted a longitudinal study in 68 adult and elderly patients with ATL treating at the Surveillance Leishmaniasis Laboratory at the Evandro Chagas Clinical Research Institute, Oswaldo Cruz Foundation (Fiocruz), from 2009 to 2012. The nutritional assessment included the body mass index (BMI) and serum albumin levels. The clinical evolution (epithelialization and wound healing) was measured up to two years after ATL treatment. Most of the sample was composed of men (71%), adults (73%), with household income of 1-5 minimum wages (79%), and incomplete elementary school (48.5%). The predominant ATL form was cutaneous (72%), and 39% presented comorbidities, the most frequent was hypertension (30.8%). The most prevalent clinical and nutritional events were: recent decrease in food intake (23.9%); nasal obstruction (22.1%); oral ulcer (14.7%), anorexia and dysphagia (13.2% each) and odynophagia (10.3%). The total healing time was 115.00 (IR=80-230) days for skin lesions, and 120.00 (IR=104.50-223.50) days for mucous membrane lesions. Low body weight in 10%, and hypoalbuminemia in 12% of the patients have been observed. Low body weight was associated with age, mucosal leishmaniasis (ML), nasal obstruction, recent decrease in food intake and hypoalbuminemia. As for serum albumin depletion, association with the ML, dyspnea, dysphagia, odynophagia, recent decrease in food intake, absence of complete healing of the skin lesions, and increased healing time for mucous membrane lesions, was observed. The ML and their events that affect the alimentary intake have been related to the impairment of the nutritional status. Additionally, serum albumin depletion negatively affected the healing of the lesions, suggesting that a nutritional intervention can increase the effectiveness of the ATL treatment. Copyright © 2013 The Authors

  4. Strong influence of polymer architecture on the microstructural evolution of hafnium-alkoxide-modified silazanes upon ceramization.

    Science.gov (United States)

    Papendorf, Benjamin; Nonnenmacher, Katharina; Ionescu, Emanuel; Kleebe, Hans-Joachim; Riedel, Ralf

    2011-04-04

    The present study focuses on the synthesis and ceramization of novel hafnium-alkoxide-modified silazanes as well as on their microstructure evolution at high temperatures. The synthesis of hafnia-modified polymer-derived SiCN ceramic nanocomposites is performed via chemical modification of a polysilazane and of a cyclotrisilazane, followed by cross-linking and pyrolysis in argon atmosphere. Spectroscopic investigation (i.e., NMR, FTIR, and Raman) shows that the hafnium alkoxide reacts with the N-H groups of the cyclotrisilazane; in the case of polysilazane, reactions of N-H as well as Si-H groups with the alkoxide are observed. Consequently, scanning and transmission electron microscopy studies reveal that the ceramic nanocomposites obtained from cyclotrisilazane and polysilazane exhibited markedly different microstructures, which is a result of the different reaction pathways of the hafnium alkoxide with cyclotrisilazane and with polysilazane. Furthermore, the two prepared ceramic nanocomposites are unexpectedly found to exhibit extremely different high-temperature behavior with respect to decomposition and crystallization; this essential difference is found to be related to the different distribution of hafnium throughout the ceramic network in the two samples. Thus, the homogeneous distribution of hafnium observed in the polysilazane-derived ceramic leads to an enhanced thermal stability with respect to decomposition, whereas the local enrichment of hafnium within the matrix of the cyclotrisilazane-based sample induces a pronounced decomposition upon annealing at high temperatures. The results indicate that the chemistry and architecture of the precursor has a crucial effect on the microstructure of the resulting ceramic material and consequently on its high-temperature behavior. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Microstructure evolution and its influence on deformation mechanisms during high temperature creep of a nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Safari, Javad [Materials Science and Engineering Department, Shahid Chamran University, Ahwaz (Iran, Islamic Republic of)], E-mail: javadsafari@yahoo.com; Nategh, Saeed [Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)], E-mail: nategh@sharif.edu

    2009-01-15

    The interaction of dislocation with strengthening particles, including primary and secondary {gamma}', during different stages of creep of Rene-80 was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). During creep of the alloy at 871 deg. C under stress of 290 MPa, the dislocation network was formed during the early stages of creep, and the dislocation glide and climb process were the predominant mechanism of deformation. The density of dislocation network became more populated during the later stages of the creep, and at the latest stage of the creep, primary particles shearing were observed alongside with the dislocation glide and climb. Shearing of {gamma}' particles in creep at 871 deg. C under stress of 475 MPa was commenced at the earlier creep times and governed the creep deformation mechanism. In two levels of examined stresses, as far as the creep deformation was controlled by glide and climb, creep curves were found to be at the second stage of creep and commence of the tertiary creep, with increasing creep rate, were found to be in coincidence with the particles shearing. Microstructure evolution, with regard to {gamma}' strengthening particles, led to particles growth and promoted activation of other deformation mechanisms such as dislocation bypassing by orowan loop formation. Dislocation-secondary {gamma}' particles interaction was detected to be the glide and climb at the early stages of creep, while at the later stages, the dislocation bypassed the secondary precipitation by means of orowan loops formation, as the secondary particle were grown and the mean inter-particle distance increased.

  6. Exponential decay of GC content detected by strand-symmetric substitution rates influences the evolution of isochore structure.

    Science.gov (United States)

    Karro, J E; Peifer, M; Hardison, R C; Kollmann, M; von Grünberg, H H

    2008-02-01

    The distribution of guanine and cytosine nucleotides throughout a genome, or the GC content, is associated with numerous features in mammals; understanding the pattern and evolutionary history of GC content is crucial to our efforts to annotate the genome. The local GC content is decaying toward an equilibrium point, but the causes and rates of this decay, as well as the value of the equilibrium point, remain topics of debate. By comparing the results of 2 methods for estimating local substitution rates, we identify 620 Mb of the human genome in which the rates of the various types of nucleotide substitutions are the same on both strands. These strand-symmetric regions show an exponential decay of local GC content at a pace determined by local substitution rates. DNA segments subjected to higher rates experience disproportionately accelerated decay and are AT rich, whereas segments subjected to lower rates decay more slowly and are GC rich. Although we are unable to draw any conclusions about causal factors, the results support the hypothesis proposed by Khelifi A, Meunier J, Duret L, and Mouchiroud D (2006. GC content evolution of the human and mouse genomes: insights from the study of processed pseudogenes in regions of different recombination rates. J Mol Evol. 62:745-752.) that the isochore structure has been reshaped over time. If rate variation were a determining factor, then the current isochore structure of mammalian genomes could result from the local differences in substitution rates. We predict that under current conditions strand-symmetric portions of the human genome will stabilize at an average GC content of 30% (considerably less than the current 42%), thus confirming that the human genome has not yet reached equilibrium.

  7. Influence of nutrients on biomass evolution in an upflow anaerobic sludge blanket reactor degrading sulfate-laden organics.

    Science.gov (United States)

    Patidar, S K; Tare, Vinod

    2004-01-01

    This paper describes the effect of the nutrients iron (Fe), nickel (Ni), zinc (Zn), cobalt (Co), and molybdenum (Mo) on biomass evolution in an upflow anaerobic sludge blanket (UASB) reactor metabolizing synthetic sulfate-laden organics at varying operating conditions during a period of 540 days. A bench-scale model of a UASB reactor was operated at a temperature of 35 degrees C for a chemical oxygen demand-to-sulfate (COD/SO4(2-)) ratio of 8.59 to 2.0, a sulfate loading rate of 0.54 to 1.88 kg SO4(2-)/m3 x d, and an organic loading rate of 1.9 to 5.75 kg COD/m3 x d. Biomass was characterized in terms of total methanogenic activity, acetate-utilizing methanogenic activity, total sulfidogenic activity, acetate-utilizing sulfidogenic activity, and scanning electron microscopy (SEM). Nickel and cobalt limitation appears to affect the activity of hydrogen-utilizing methane-producing bacteria (HMPB) significantly without having an appreciable effect on the activity of acetate-utilizing methane-producing bacteria (AMPB). Nickel and cobalt supplementation resulted in increased availability and, consequently, restoration of biomass activity and process performance. Iron limitation and sulfidogenic conditions resulted in the growth of low-density, hollow, fragile granules that washed out, causing process instability and performance deterioration. Iron and cobalt supplementation indicated significant stimulation of AMPB with slight inhibition of HMPB. Examination of biomass through SEM indicated a population shift with dominance of sarcina-type organisms and the formation of hollow granules. Granule disintegration was observed toward the end of the study.

  8. Space radiation effects

    International Nuclear Information System (INIS)

    Li Shiqing; Yan Heping

    1995-01-01

    The authors briefly discusses the radiation environment in near-earth space and it's influences on material, and electronic devices using in space airship, also, the research developments in space radiation effects are introduced

  9. Influence of compaction pressure on the morphology and phase evolution of porous NiTi alloy prepared by SHS technique

    Directory of Open Access Journals (Sweden)

    Sirikul Wisutmethangoon

    2008-08-01

    Full Text Available The influence of compaction pressure on the pore morphology of porous NiTi shape memory alloys (SMAs fabricated by self-propagating high-temperature synthesis (SHS was investigated. The compaction pressure has a significant effect on the combustion temperature and pore morphology. The porous NiTi (SMAs thus obtained have the porosity of product in the range of 37.4-57.9 vol.%. The open porosity ratios were observed to be greater than 88%, which indicatesthat porous NiTi (SMAs are suitable for biomedical applications. In addition, the predominant phases in the porous product are B2(NiTi and B19’(NiTi with small amounts of secondary phases, NiTi2 and Ni4Ti3.

  10. Evidence of molecular evolution driven by recombination events influencing tropism in a novel human adenovirus that causes epidemic keratoconjunctivitis.

    Directory of Open Access Journals (Sweden)

    Michael P Walsh

    2009-06-01

    the first genomic, bioinformatic, and biological descriptions of the molecular evolution events engendering an emerging pathogenic adenovirus.

  11. Influence of antioxidants synthesized by plants on physico-chemical and microbiological evolution of Callovo-Oxfordian clay material

    International Nuclear Information System (INIS)

    Ubersfeld, Dimitri

    2016-01-01

    This study is a part of the deep disposal site development for radioactive waste in Meuse-Haute Marne (France), most specifically on the bio-physico-chemical conversion of sedimentary clay rocks (Callovo- Oxfordian, COx), excavated and stored on surface in the form of heap. During the experimental and operational phases, several million cubic meters of argillite will be excavated. Argillite stored in the open air will be exposed to meteoritic alterations, oxidizing conditions of surface and colonized biologically (plants, bacteria, fungi). The aim of the thesis is to study the impact of naturally derived antioxidants from revegetation of heap with antioxidant-producing plants on the physical, chemical or microbial weathering processes of argillite. This work was designed to (i) identify suitable naturally derived antioxidants and the plants to produce them (ii) assess the antioxidant inhibitory effects on weathering and leaching COx metals in the laboratory, (iv) field test selected plants on the heap, (iii) follow in situ physicochemical and microbiological evolution of the argillite heap planted with antioxidant producing plants. In the laboratory, percolating model antioxidants of Lamiaceae (linalool, thymol, carvacrol) through a packed column of argillite showed variable water weathering/leaching rate depending on the metal elements present; very low for aluminum (<1 o/oo), between 1-3% for other metals (Ca, Mg, Fe...) and reach more than 60% for sodium. With thymol at 20 mg/l for 3 months, it was found that there are a decrease in sulfur leached amount and the metal elements from the sulfides (Fe, As) and carbonates (Ca, Sr) and inhibition of bacterial and fungal microflora growths. However, intake of artificial root exudates in columns stimulates microbial growth, improves the availability of aluminum, iron and provides sequestration of calcium. Among the tested plants, lavender and lavandin were selected. Two successive plantation tests were carried out in

  12. Influence of chemical disorder on the electronic level spacing distribution of the Ag{sub 5083} nanoparticle: A tight-binding study

    Energy Technology Data Exchange (ETDEWEB)

    Medrano, L.R., E-mail: leonardoms20@gmail.com [Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima 14 (Peru); Landauro, C.V., E-mail: clandauros@unmsm.edu.pe [Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima 14 (Peru)

    2013-03-01

    In the present work we study, employing a tight-binding Hamiltonian, the influence of chemical disorder on the electronic level spacing distribution of a silver nanoparticle containing 5083 atoms (∼ 5.5 nm). This nanoparticle was obtained by molecular dynamics simulations with a tight-binding atomic potential. The results indicate that in the absence of disorder the level spacing distributions are similar to those expected for systems belonging to the Gaussian Orthogonal Ensemble. Whereas, after increasing the chemical disorder, the electronic level spacing distribution and the Σ{sub 2} statistics tend to the corresponding form for the Poisson Ensemble, i.e., the silver nanoparticle acquires an insulating character which is expected for strongly disordered systems. Hence, this kind of disorder produces the localization of the electronic states of the nanoparticle.

  13. Influence of temperature histories during reactor startup periods on microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Kasahara, Shigeki, E-mail: kasahara.shigeki@jaea.go.jp [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kitsunai, Yuji [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Chimi, Yasuhiro [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Chatani, Kazuhiro; Koshiishi, Masato [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Nishiyama, Yutaka [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2016-11-15

    This paper addresses influence of two different temperature profiles during startup periods in the Japan Materials Testing Reactor and a boiling water reactor upon microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons to about 1 dpa and 3 dpa. One of the temperature profiles was that the specimens experienced neutron irradiation in both reactors, under which the irradiation temperature transiently increased to 290 °C from room temperature with increasing reactor power during reactor startup periods. Another was that the specimens were pre-heated to about 150 °C prior to the irradiation to suppress the transient temperature increase. Tensile tests at 290 °C and Vickers hardness tests at room temperature were carried out, and their microstructures were observed by FEG-TEM. Difference of the temperature profiles was observed obviously in interstitial cluster formation, in particular, growth of Frank loops. Although influence of neutron irradiation involving transient temperature increase to 290 °C from room temperature on the yield strength and the Vickers hardness is buried in the trend curves of existing data, the influence was also found certainly in increment of in yield strength, existence of modest yield drop, and loss of strain hardening capacity and ductility. As a result, Frank loops, which were observed in austenitic stainless steel irradiated at doses of 1 dpa or more, seemed to have important implications regarding the interpretation of not irradiation hardening, but deformation of the austenitic stainless steel.

  14. Adaptability and evolution.

    Science.gov (United States)

    Bateson, Patrick

    2017-10-06

    The capacity of organisms to respond in their own lifetimes to new challenges in their environments probably appeared early in biological evolution. At present few studies have shown how such adaptability could influence the inherited characteristics of an organism's descendants. In part, this has been because organisms have been treated as passive in evolution. Nevertheless, their effects on biological evolution are likely to have been important and, when they occurred, accelerated the pace of evolution. Ways in which this might have happened have been suggested many times since the 1870s. I review these proposals and discuss their relevance to modern thought.

  15. Study by simulation the influence of temperature on the formation of space charge in the dielectric multilayer Under DC Electric stress

    Directory of Open Access Journals (Sweden)

    Y. A. Baadj

    2017-06-01

    Full Text Available Multidielectric polyethylene is a material that is generally employed as insulation for  the HVDC isolations. In this paper, the influence of temperature on space charge dynamics has been studied, low-density polyethylene (LDPE and Fluorinated Ethylene Propylene (FEP sandwiched between two electrodes were subjected to voltage application of 5kV (14.3 kV/mm for extended duration of time and the space charge measurements were taken using bipolar model is one-dimensional, taking into account trapping, detrapping and the rencommbinaison in order to determine the charge density and electric field of the sample depending on the thickness. The simulation was carried out at three different temperatures (20, 40,  and 60°C. The results of this model going to compare with experimental space charge measurements . Finally, simulation results demonstrated that the temperature has many effects on the dynamic space charge  and of influences the charge injection, charge mobility, electrical conduction, trapping and detrapping.

  16. Evolution of Fe based intermetallic phases in Al–Si hypoeutectic casting alloys: Influence of the Si and Fe concentrations, and solidification rate

    Energy Technology Data Exchange (ETDEWEB)

    Gorny, Anton; Manickaraj, Jeyakumar [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, ON, Canada L8S 4L7 (Canada); Cai, Zhonghou [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Shankar, Sumanth, E-mail: shankar@mcmaster.ca [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, ON, Canada L8S 4L7 (Canada)

    2013-11-15

    Highlights: •Anomalous evolution of Fe based intermetallic phases in Al–Si–Fe alloys. •XRF coupled with nano-diffraction to confirm the nano-size Fe intermetallic phases. •Crystallography of the θ-Al{sub 13}Fe{sub 4}, τ{sub 5}-Al{sub 8}Fe{sub 2}Si and τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2} phases. •Peritectic reactions involving the Fe intermetallic phases in Al–Si–Fe alloys. -- Abstract: Al–Si–Fe hypoeutectic cast alloy system is very complex and reported to produce numerous Fe based intermetallic phases in conjunction with Al and Si. This publication will address the anomalies of phase evolution in the Al–Si–Fe hypoeutectic casting alloy system; the anomaly lies in the peculiarities in the evolution and nature of the intermetallic phases when compared to the thermodynamic phase diagram predictions and past publications of the same. The influence of the following parameters, in various combinations, on the evolution and nature of the intermetallic phases were analyzed and reported: concentration of Si between 2 and 12.6 wt%, Fe between 0.05 and 0.5 wt% and solidification rates of 0.1, 1, 5 and 50 K s{sup −1}. Two intermetallic phases are observed to evolve in these alloys under these solidification conditions: the τ{sub 5}-Al{sub 8}SiFe{sub 2} and τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2}. The τ{sub 5}-Al{sub 8}SiFe{sub 2} phase evolves at all levels of the parameters during solidification and subsequently transforms into the τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2} through a peritectic reaction when promoted by certain combinations of solidification parameters such as higher Fe level, lower Si level and slower solidification rates. Further, it is also hypothesized from experimental evidences that the θ-Al{sub 13}Fe{sub 4} binary phase precludes the evolution of the τ{sub 5} during solidification and subsequently transforms into the τ{sub 6} phase during solidification. These observations are anomalous to the publications as prior art and

  17. EVOLUTION OF THE MAIN MODELS OF INTEGRATED MARKETING COMMUNICATIONS WHO HAVE THE ROLE TO INFLUENCE CONSUMER BUYING BEHAVIOR

    Directory of Open Access Journals (Sweden)

    OANCEA OLIMPIA ELENA MIHAELA

    2015-03-01

    Full Text Available The models of integrated marketing communication have become today a very useful tool, that can provide companies a sustainable competitive advantage. The integrated marketing communication identifies with today's market dynamics and learn organizations how easy it can be to prosper in an environment where there are produced changes in an alarming way. In an economy with a strong competition character, organizations must capitalize integrated marketing communication in a way more efficiently, for to ensure the creation and maintenance of longterm relationships with current and potential customers. A product or a brand exist in the consumer's mind there not only because of experience with it, but also due to the medium and long term effects on that a message built on base the wishes, expectations or consumer preferences is transmitted simultaneously through as many tools of communication. Building and managing relationships with consumers can have a direct and positive effect on efficiency of the results of communication of a company. Changes in the business environment, along with technological innovation, increasing consumer sophistication and changes in marketing communications practices, have led organizations to seek to improve relationships with their consumers, and to strive to deliver consistent messages to all stakeholders - consumers, employees, company partners, the state, local governments, suppliers - across a wide range of integrated marketing communications channels.Therefore, the purpose of this article is to identify and analyze the main models of integrated marketing communication that can influence the consumer behaviour.

  18. From information and consultation to citizen influence and power. 10-Year Evolution in Public involvement in Radioactive Waste Management

    International Nuclear Information System (INIS)

    2010-09-01

    The OECD/NEA Forum on Stakeholder Confidence (FSC) was created in 2000 to promote the sharing of international experience in addressing the societal dimension of radioactive waste management. It explores means of ensuring an effective dialogue amongst all stakeholders and to strengthen confidence in decision-making processes. The working definition given to the term 'stakeholder' is: Any actor - institution, group or individual - with an interest or with a role to play in the process. The FSC has documented a wealth of experience through topical sessions and studies and, in particular, through its many national workshops and community visits. The present flyer highlights the growing stakeholder empowerment in radioactive waste management observed since the inception of the Forum ten years ago. Important changes have taken place in citizen participation for radioactive waste management in the past decade: a shift from information and consultation towards citizen influence and power, and a shift from overt conflict or resigned acceptance to volunteering and collaboration by local communities. Overall, there is recognition of the legitimacy of community empowerment measures and socio-economic benefits, and there exist now a great variety of administrative formats for collaboration. New ideals and bases for collaboration have also emerged. These are: mutual learning, adding value to the host community/region, and sustainable development

  19. Influence of certain forces on evolution of synonymous codon usage bias in certain species of three basal orders of aquatic insects.

    Science.gov (United States)

    Selva Kumar, C; Nair, Rahul R; Sivaramakrishnan, K G; Ganesh, D; Janarthanan, S; Arunachalam, M; Sivaruban, T

    2012-12-01

    Forces that influence the evolution of synonymous codon usage bias are analyzed in six species of three basal orders of aquatic insects. The rationale behind choosing six species of aquatic insects (three from Ephemeroptera, one from Plecoptera, and two from Odonata) for the present analysis is based on phylogenetic position at the basal clades of the Order Insecta facilitating the understanding of the evolution of codon bias and of factors shaping codon usage patterns in primitive clades of insect lineages and their subtle differences in some of their ecological and environmental requirements in terms of habitat-microhabitat requirements, altitudinal preferences, temperature tolerance ranges, and consequent responses to climate change impacts. The present analysis focuses on open reading frames of the 13 protein-coding genes in the mitochondrial genome of six carefully chosen insect species to get a comprehensive picture of the evolutionary intricacies of codon bias. In all the six species, A and T contents are observed to be significantly higher than G and C, and are used roughly equally. Since transcription hypothesis on codon usage demands A richness and T poorness, it is quite likely that mutation pressure may be the key factor associated with synonymous codon usage (SCU) variations in these species because the mutation hypothesis predicts AT richness and GC poorness in the mitochondrial DNA. Thus, AT-biased mutation pressure seems to be an important factor in framing the SCU variation in all the selected species of aquatic insects, which in turn explains the predominance of A and T ending codons in these species. This study does not find any association between microhabitats and codon usage variations in the mitochondria of selected aquatic insects. However, this study has identified major forces, such as compositional constraints and mutation pressure, which shape patterns of codon usage in mitochondrial genes in the primitive clades of insect lineages.

  20. Orogen-parallel variation in exhumation and its influence on critical taper evolution: The case of the Emilia-Romagna Apennine (Italy)

    Science.gov (United States)

    Bonini, Marco

    2018-03-01

    The Northern Apennine prowedge exposes two adjacent sectors showing a marked along-strike change in erosion intensity, namely the Emilia Apennine to the northwest and the Romagna Apennine to the southeast. This setting has resulted from Pliocene erosion (≤5 Ma) and exhumation, which have affected the whole Romagna sector and mostly the watershed ridge in Emilia. Such an evolution has conceivably influenced the equilibrium of this fold-and-thrust belt, which can be evaluated in terms of critical Coulomb wedge theory. The present state of the thrust wedge has been assessed by crosschecking wedge tapers measured along transverse profiles with fluid pressure values inferred from deep wellbores. The interpretation of available data suggests that both Emilia and Romagna are currently overcritical. This condition is compatible with the presence in both sectors of active NE-dipping normal faults, which would work to decrease the surface slope of the orogenic wedge. However, the presence of Late Miocene-Pliocene passive-roof and out-of-sequence thrusts in Romagna may reveal a past undercritical wedge state ensuing during the regional erosion phase, thereby implying that the current overcritical condition would be a recent feature. The setting of the Emilia Apennine (i.e., strong axial exhumation and limited erosion of the prowedge) suggests instead a long lasting overcritical wedge, which was probably contemporaneous with the Pliocene undercritical wedge in Romagna. The reasons for this evolution are still unclear, although they may be linked to lithosphere-scale processes that have promoted the uplift of Romagna relative to Emilia. The lessons from the Northern Apennine thus suggest that erosion and exhumation have the ability to produce marked along-strike changes in the equilibrium of a fold-and-thrust belt.

  1. An Experimental Study on the Influence of Soundscapes on People’s Behaviour in an Open Public Space

    OpenAIRE

    Francesco Aletta; Federica Lepore; Eirini Kostara-Konstantinou; Jian Kang; Arianna Astolfi

    2016-01-01

    Several studies have investigated how environmental sounds and music can modulate people’s behaviours, particularly in marketing research. However, there are relatively few examples of research about such relationships with a focus on the management of urban public spaces. The current study investigated an open public space used mainly as a pedestrian crossing to analyse the relationship between the audio stimuli and peoples’ behaviours. An experiment relying on covert behavioural observation...

  2. An Experimental Study on the Influence of Soundscapes on People’s Behaviour in an Open Public Space

    OpenAIRE

    Aletta, F.; Lepore, F.; Kostara-Konstantinou, E.; Kang, J.; Astolfi, A.

    2016-01-01

    Several studies have investigated how environmental sounds and music can modulate\\ud people’s behaviours, particularly in marketing research. However, there are relatively few examples\\ud of research about such relationships with a focus on the management of urban public spaces.\\ud The current study investigated an open public space used mainly as a pedestrian crossing to analyse\\ud the relationship between the audio stimuli and peoples’ behaviours. An experiment relying on\\ud covert behaviou...

  3. Investigating the influence of epitaxial modulation on the evolution of superhardness of the VN/TiB{sub 2} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yupeng [Energy and Materials Engineering Centre, College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Tianjin International Joint Research Centre of Surface Technology for Energy Storage Materials, Tianjin 300387 (China); Dong, Lei, E-mail: dlei0008@126.com [Energy and Materials Engineering Centre, College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Tianjin International Joint Research Centre of Surface Technology for Energy Storage Materials, Tianjin 300387 (China); Liu, Na; Yu, Jiangang; Li, Chun [Energy and Materials Engineering Centre, College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Tianjin International Joint Research Centre of Surface Technology for Energy Storage Materials, Tianjin 300387 (China); Li, Dejun, E-mail: dejunli@mail.tjnu.edu.cn [Energy and Materials Engineering Centre, College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Tianjin International Joint Research Centre of Surface Technology for Energy Storage Materials, Tianjin 300387 (China)

    2016-12-30

    Graphical abstract: The novel VN/TiB{sub 2} multilayers were produced by a magnetron sputtering system. Reasonable modulation structure affected properties of the multilayers. The double epitaxial growth as shown in HRTEM images was newly found to be a main reason for coherent growth of the VN/TiB{sub 2} multilayers within a certain thickness. The coherent growth model of the multilayer was also used to explain the growth mechanism of the VN/TiB{sub 2} multilayers in this work, which provided a useful inspiration to understand the strategies to enhance the multilayers’ engineering applications. - Highlights: • The VN/TiB{sub 2} multilayers are produced by magnetron sputtering. • A kind of second epitaxial growth is found in multilayer. • The coherent growth model is designed to explain the growth mechanism. • Second epitaxial growth promotes to form superhardness. • Coherent growth appears twice with modulation ratios decreasing. - Abstract: A series of the VN/TiB{sub 2} nanomultilayers with different modulation ratios (t{sub VN}:t{sub TiB2}) and different modulation periods were synthesized via a magnetron sputtering system. The cross-sectional transmission electron microscopy (TEM) and x-ray diffraction (XRD) examinations indicated that in the alternately deposited monolayers of the VN and TiB{sub 2}, due to the influence of the crystal (111){sub VN} texture, TiB{sub 2} layer presented epitaxial growth on the surface of the VN layer when its t{sub VN}:t{sub TiB2} was 5:1. Moreover, the formation of the TiB{sub 2} crystal promoted the growth of (200){sub VN} and significantly improved the preferential growth of nanomultilayers. With decreasing t{sub VN}:t{sub TiB2} to 1:7, the thin VN layer was crystallized under the introduction of crystalline TiB{sub 2} layers. A type of double epitaxial growth was observed to be a main reason for the coherent growth of the VN/TiB{sub 2} nanomultilayers within a certain thickness. Consequently, the multilayers

  4. Evolution of Things

    OpenAIRE

    Eiben, A. E.; Ferreira, N.; Schut, M.; Kernbach, S.

    2011-01-01

    Evolution is one of the major omnipresent powers in the universe that has been studied for about two centuries. Recent scientific and technical developments make it possible to make the transition from passively understanding to actively mastering evolution. As of today, the only area where human experimenters can design and manipulate evolutionary processes in full is that of Evolutionary Computing, where evolutionary processes are carried out in a digital space, inside computers, in simulat...

  5. Variability of albumin in blood serum as a possible reflection of evolutional influence of diluvial horses on population of native mountain horse in Serbia

    Directory of Open Access Journals (Sweden)

    Trailović Ružica

    2013-01-01

    Full Text Available Native mountain horse is an autochthonous ungulata with a domicile extending to the whole mountaneous region of Serbia, south of the Sava and Danube rivers. Along with native horses of other Balkan countries it is classified as Mediterranean pony, but unlike Balkan horses such as Skiros, Pinea, Pindos, Karakachan, Bosnian mountineous horse etc., mountineous horses in Serbia neither have been morphologically described nor were of concern to the scientific community till the end of the twentieth century. Investigations of albumin polymorphism in blood serum of native mountain horse were taken within a comprehensive reserch on morphologic, physiologic and genetic structure of this autochtonous ungulata breed. On the basis of the results obtained by electrophoretic separation of albumine types in native mountaneous horse blood serum, there were determined four albumine phenotypes: AA, AB, BB and BI which are inherited by three autosomal alleles AlA, Alb, All . The appearance of All allele in native mountaneous horse population points out to diluvial forest horse impact on process of microevolution of autochtonous native mountaneous horse. Occidental- specific albumin isoforms presence indicate the necessity of thorough study of evolution position and historic influence of different ancestors, and especially occidental horses on native mountain horse population in Serbia.

  6. Evolution of anomalies of salinity of surface waters of Arctic Ocean and their possible influence on climate changes

    Science.gov (United States)

    Popov, A.; Rubchenia, A.

    2009-04-01

    flaw lead polynyas there is a reduction of average salinity of surface waters of Arctic basin. In the winter period obvious influence of waters of a river runoff on a hydrological situation of this or that sea is limited to a zone of distribution of fast ice and a narrow zone of flaw lead polynyas between fast ice and drift ice. That fresh water from the Arctic seas is transferred in the Arctic basin. There should be a certain effective mechanism to carry it. Presence of clear interrelation of salinity of surface waters and volumes of ice formed in polynyas, allows us to offer the following circuit of formation of average salinity of surface waters in the Arctic basin. The ice formed in polynya, is constantly taken out for limits of an area of flaw lead polynyas. This ice accumulates the fresh water acting with a river runoff. New ice hummocking and accumulate snow - the next source of fresh water. In the summer period ice is melting and forms surface fresh layer. In the cold period of year, presence of thick ice not allows accumulating all fresh water, and the zone of fresh water is forming. These fresh water areas could exist for months. In the reports [1] was offered a hypothesis describing formation of distant connections in climatic system. In the hypothesis offered by us about a role of polynyas in formation of distant feedback in climatic system the most important and, unfortunately, the least certain parameter is «reaching time» of climatic signal from a place of origin (in flaw lead polynya area) up to the Greenland sea and Northern Atlantic. For an estimation of reaching time» we tried to trace drift of this anomaly from polynyas to Greenland Sea. For the initial moment of anomaly genesis month of the maximal development of polynya (when ice production of it was maximal) was chosen. Core of freshwater anomaly was determined for several polynyas. Using results of our simulations, data from database with areas of polynyas, wind stress data and current speed

  7. Hedonic pricing analysis of the influence of urban green spaces onto residential prices : the case of Leipzig, Germany

    NARCIS (Netherlands)

    Liebelt, Veronika; Bartke, Stephan; Schwarz, Nina

    2018-01-01

    In the light of global urbanization and biodiversity loss, ecosystem services provided by urban green spaces (UGS) are becoming increasingly important, not least as a recovery and recreation opportunity for citizens. The valuation of UGS is significant for urban planners, who make decisions on the

  8. The influence of personal belief, agency mission and city size on open space decision making processes in three southwestern cities

    Science.gov (United States)

    Megan Friggens; Carol Raish; Deborah Finch; Alice McSweeney

    2015-01-01

    The southwest has experienced dramatic population increases over the last 30 years, a trend that is expected to continue. Open space conservation is important both from the standpoint of preserving ecosystem services as well as maintaining quality of life for urban populations. Federal agencies manage a large proportion of the public land in the Southwestern U.S. We...

  9. Reward magnitude, but not time of day, influences the trial-spacing effect in autoshaping with rats.

    Science.gov (United States)

    Thomas, B; Huneycutt, D; Papini, M R

    1998-12-01

    The arousal hypothesis of the trial-spacing effect suggests that spaced-trial training increases emotional arousal and thus invigorates Pavlovian behavior, relative to massed-trial conditions. Emotional arousal was manipulated by varying reinforcer magnitude during training (either one or five food pellets/trial, across groups). In addition, autoshaping training was administered either in the morning (0900 h) or in the evening (1700 h). Rats were housed in an enclosed colony room and exposed to a regular light:dark cycle (light from 0700 to 1900 h). Available evidence indicates that reinforcer magnitude and time of day are related to arousal levels. As expected, a larger reinforcer magnitude led to a highly significant trial spacing effect. Evening training led to a higher response rate than morning training, but the trial-spacing effect was equally strong whether training was administered in the morning or in the evening. These results provide partial support for the arousal hypothesis and are discussed in the context of research on schedule-induced behavior.

  10. Lie symmetries for systems of evolution equations

    Science.gov (United States)

    Paliathanasis, Andronikos; Tsamparlis, Michael

    2018-01-01

    The Lie symmetries for a class of systems of evolution equations are studied. The evolution equations are defined in a bimetric space with two Riemannian metrics corresponding to the space of the independent and dependent variables of the differential equations. The exact relation of the Lie symmetries with the collineations of the bimetric space is determined.

  11. Lead-lead systematics, the 'age of the earth' and the chemical evolution of our planet in a new representation space

    International Nuclear Information System (INIS)

    Manhes, G.; Allegre, C.J.; Dupre, B.; Hamelin, B.

    1979-01-01

    A new way to look at the Pb-Pb isotopic results is proposed. The characteristics are as follows: (1) knowledge of the initial ratios of cogenetic samples is not necessary to discuss the isotopic evolution of parent bodies; and (2) linear representations are permissible thus allowing for a simplified treatment in comparison to the classical 206 Pb/ 204 Pb vs. 207 Pb/ 204 Pb diagram. Using Pb-Pb data of terrestrial samples, either stated in past reasearch or as recently measured by the laboratory, problems such as the Earth's age and its evolution are being dealt with utilising this new formalism. The treatment for a set of mantle whole-rock measurements, assuming only the initial isotopic composition furnishes a value for the Earth's age of 4.49 +- 0.17 b.y. (Auth.)

  12. Space biology research development

    Science.gov (United States)

    Bonting, Sjoerd L.

    1993-01-01

    The purpose of the Search for Extraterrestrial Intelligence (SETI) Institute is to conduct and promote research related activities regarding the search for extraterrestrial life, particularly intelligent life. Such research encompasses the broad discipline of 'Life in the Universe', including all scientific and technological aspects of astronomy and the planetary sciences, chemical evolution, the origin of life, biological evolution, and cultural evolution. The primary purpose was to provide funding for the Principal Investigator to collaborate with the personnel of the SETI Institute and the NASA-Ames Research center in order to plan and develop space biology research on and in connection with Space Station Freedom; to promote cooperation with the international partners in the space station; to conduct a study on the use of biosensors in space biology research and life support system operation; and to promote space biology research through the initiation of an annual publication 'Advances in Space Biology and Medicine'.

  13. Space-time-modulated stochastic processes

    Science.gov (United States)

    Giona, Massimiliano

    2017-10-01

    Starting from the physical problem associated with the Lorentzian transformation of a Poisson-Kac process in inertial frames, the concept of space-time-modulated stochastic processes is introduced for processes possessing finite propagation velocity. This class of stochastic processes provides a two-way coupling between the stochastic perturbation acting on a physical observable and the evolution of the physical observable itself, which in turn influences the statistical properties of the stochastic perturbation during its evolution. The definition of space-time-modulated processes requires the introduction of two functions: a nonlinear amplitude modulation, controlling the intensity of the stochastic perturbation, and a time-horizon function, which modulates its statistical properties, providing irreducible feedback between the stochastic perturbation and the physical observable influenced by it. The latter property is the peculiar fingerprint of this class of models that makes them suitable for extension to generic curved-space times. Considering Poisson-Kac processes as prototypical examples of stochastic processes possessing finite propagation velocity, the balance equations for the probability density functions associated with their space-time modulations are derived. Several examples highlighting the peculiarities of space-time-modulated processes are thoroughly analyzed.

  14. Tectonic evolution of the central-eastern sector of Trans Mexican Volcanic Belt and its influence on the eruptive history of the Nevado de Toluca volcano (Mexico)

    Science.gov (United States)

    Bellotti, F.; Capra, L.; Groppelli, G.; Norini, G.

    2006-11-01

    The Nevado de Toluca is an andesitic to dacitic stratovolcano of Late Pliocene-Holocene age located within the central and eastern sectors of the Trans Mexican Volcanic Belt. Morphostructural analysis, aerial photograph and satellite image interpretation, structural analysis and geological fieldwork were methods used to investigate the relationship between the evolution of the volcano and the tectonic framework of its basement. The study revealed that the area of Nevado de Toluca is affected by three main fault systems that intersect close to the volcanic edifice. These are from oldest to youngest, the Taxco-Querétaro, San Antonio and Tenango fault systems. The NNW-SSE Taxco-Querétaro fault system was active in the area since Early Miocene, and is characterized by right-lateral transtensive movement. Its reactivation during Early to Middle Pleistocene was responsible for the emplacement of andesitic to dacitic lava flows and domes of La Cieneguilla Supersynthem. The NE-SW San Antonio fault system was active during Late Pliocene, before the reactivation of the Taxco-Querétaro fault system, and is characterized by extensional left-lateral oblique-slip kinematics. The youngest is the E-W Tenango fault system that has been active since Late Pleistocene. This fault system is characterized by transtensive left-lateral strike-slip movement, and partly coeval with the youngest eruptive phase, the Nevado Supersynthem, which formed the present summit cone of the Nevado de Toluca volcano. The stress re-orientation from the Taxco-Querétaro to the Tenango fault system during Late Pleistocene is responsible for the ˜ 1 Ma hiatus in the magmatic activity between 1.15 Ma and 42 ka. After this period of repose, the eruptive style drastically changed from effusive to explosive with the emission of dacitic products. The methodology presented here furnish new data that can be used to better assess the complex structural evolution of this sector of the Trans Mexican Volcanic Belt

  15. Evolution algebras generated by Gibbs measures

    International Nuclear Information System (INIS)

    Rozikov, Utkir A.; Tian, Jianjun Paul

    2009-03-01

    In this article we study algebraic structures of function spaces defined by graphs and state spaces equipped with Gibbs measures by associating evolution algebras. We give a constructive description of associating evolution algebras to the function spaces (cell spaces) defined by graphs and state spaces and Gibbs measure μ. For finite graphs we find some evolution subalgebras and other useful properties of the algebras. We obtain a structure theorem for evolution algebras when graphs are finite and connected. We prove that for a fixed finite graph, the function spaces have a unique algebraic structure since all evolution algebras are isomorphic to each other for whichever Gibbs measures are assigned. When graphs are infinite graphs then our construction allows a natural introduction of thermodynamics in studying of several systems of biology, physics and mathematics by theory of evolution algebras. (author)

  16. Influence of Extrinsic Information Scaling Coefficient on Double-Iterative Decoding Algorithm for Space-Time Turbo Codes with Large Number of Antennas

    Directory of Open Access Journals (Sweden)

    TRIFINA, L.

    2011-02-01

    Full Text Available This paper analyzes the extrinsic information scaling coefficient influence on double-iterative decoding algorithm for space-time turbo codes with large number of antennas. The max-log-APP algorithm is used, scaling both the extrinsic information in the turbo decoder and the one used at the input of the interference-canceling block. Scaling coefficients of 0.7 or 0.75 lead to a 0.5 dB coding gain compared to the no-scaling case, for one or more iterations to cancel the spatial interferences.

  17. Glass melting and its innovation potentials: The combination of transversal and longitudinal circulations and its influence on space utilisation

    Czech Academy of Sciences Publication Activity Database

    Polák, M.; Němec, Lubomír

    2011-01-01

    Roč. 357, 16-17 (2011), s. 3108-3116 ISSN 0022-3093 R&D Projects: GA MPO 2A-1TP1/063 Institutional research plan: CEZ:AV0Z40320502 Keywords : space utilisation * sand dissolution * bubble removal * flow patterns * model furnace Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.537, year: 2011

  18. BIOGAS PLANT AS AN ELEMENT THAT HAS A POSITIVE INFLUENCE ON THE ENVIRONMENTAL CHANGES OF RURAL SPACE

    OpenAIRE

    Wojciech Pawłowski

    2017-01-01

    In the contemporary rural landscape, an agricultural biogas plant is becoming an increasingly frequent element of agricultural installations. There is a need to ask an important question: is a new technology, such as biogas plants with medium power of 1MW, listed as investments which can have significant environmental impacts? This question is becoming an integral part of rural space as a new form of village buildings. The inevitable changes in the rural landscape and the way of carrying out ...

  19. An Experimental Study on the Influence of Soundscapes on People’s Behaviour in an Open Public Space

    Directory of Open Access Journals (Sweden)

    Francesco Aletta

    2016-09-01

    Full Text Available Several studies have investigated how environmental sounds and music can modulate people’s behaviours, particularly in marketing research. However, there are relatively few examples of research about such relationships with a focus on the management of urban public spaces. The current study investigated an open public space used mainly as a pedestrian crossing to analyse the relationship between the audio stimuli and peoples’ behaviours. An experiment relying on covert behavioural observation was performed. During the experiment, three different music stimuli and a control condition (i.e., no music were reproduced in order to find out firstly whether music compared to no music could elicit an increase in the number of people stopping in the investigated area, and secondly whether music is associated with a longer duration of stay for those who stop. Results showed that the presence of music had no effect on the number of people stopping in the area, but it had a statistically significant effect on the duration of stay for those who stopped. The above findings support the idea that people felt more invited to stay in the area with music rather than with no music, and suggest that the acoustical manipulation of the existing sound environment could provide soundscape strategies capable of promoting social cohesion in public spaces.

  20. Influence of space weather on human organism at different geo-latitudes: telecommunication helio-medical monitoring "Geliomed" 2003-2010

    Science.gov (United States)

    Ragulskaya, Maria; Obridko, Vladimir; Samsonov, Sergey; Vitaliy, Vishnevskey; Grigoryev, Pavel; Valeriy, Pipin; Khabarova, Olga

    ECG parameters occurs nearly simultaneously for all the centers. The higher latitude, the greater amplitude of the ECG parameters change. The properties of the detected phenomena can be summarized as follows: -The dynamics of adaptation programs changes during the storm. The maximum amplitude of change is observed for the healthy patients. -The number of none-typical ECG beats increase; -There are no clear evidences for variations of RR intervals during geomagnetic storms. -Man are more sensitive to magnetic storms, while endogenous rhythms predominate for females; Additionally, we find, that the embedding of ECG time series in 3D phase space can be considered as a mix of a few states. At the rest, the occurrence of the basic ECG state compare to additional ones is about 8:2. The occurrence of the basic state increases after the stress. Thus, the external stress may change the relative disorder of the system. To understand the origin of the standard cardio-cycle changes we reconstruct of the dynamical model of the individual cardiac beat. The reconstruction reveals that the typical evolution of the cardiac rhythm includes the drift of attractor in the embedding space and the sudden change between a few basic patterns of attractor. However one of pattern is always dominating. These several pattern of ECG beat attractor can be ascribed to a several states of the system. Qualitatively, the nonlinear ECG dynamics is defined by the stationary points, which are inside into Q and T waves. Conclusions: many-year telecommunication heliomedical monitoring in different lat-itudes showed, that space and geophysical factor act as a training factor for the adaptation-resistant member of the population. It serve as a channel for rejection of nonviable members of the population, synchronize the total populations rhythms, create conditions for generation of new information in the process of evolution adaptation of biological systems in general.

  1. Moisture condensation on building envelopes in differential ventilated spaces in the tropics: quantitative assessment of influencing factors

    Directory of Open Access Journals (Sweden)

    Ali Maisarah

    2016-01-01

    Full Text Available Ventilation systems play a significant role in maintaining the indoor thermal and hygric balance. Nevertheless, the systems had been implicated to result in many problems. In the tropical climate, especially for energy efficiency purposes, building spaces are operated with differential ventilation. Such spaces operate on 24-hrs basis, some on 8-hrs while others are either naturally ventilated or served with mechanical supply-exhaust fan systems with non-conditioned outdoor air. This practice had been found to result in condensation problems. This study involves a quantitative appraisal of the effect of operative conditions and hygrothermal quality of building envelopes on condensation risk. The in-situ experiment is combined with an analytical approach to assessing the hygrothermal quality of building envelopes in a tropical climate building under differential ventilation between adjacent spaces. The case-studied building is with a known history of condensation and associated damages including mould growth. The microclimate measurement and hygrothermal performance of the wall and floor against condensation and mould growth risks had been previously reported elsewhere. As a step further, the present study evaluates the effects of various envelope insulation types and configurations together with the HVAC cooling set-points on envelope hygrothermal performance. The results revealed that overcooling the air-conditioned side increases condensation risk on the non-air-conditioned side of the envelopes. The envelopes failed criteria for surface condensation at existing operative conditions irrespective of envelope hygrothermal quality improvements. However, the envelope performed well at improved cooling operative conditions even at existing envelope hygrothermal quality. It is, therefore, important to ascertain the envelope hygrothermal quality as well the cooling operative conditions while embarking on energy efficiency operations in mechanical

  2. An estimate of the outgassing of space payloads, their internal pressures, contaminations and gaseous influences on the environment

    Science.gov (United States)

    Scialdone, J. J.

    1985-01-01

    Experimentally measured outgassing as a function of time is presented for 14 space systems including several spacecraft instruments, spacecraft, the shuttle bay, and a spent solid fuel motor. The weights, volumes, and some of the scientific functions of the instruments involved are indicated. The methods used to obtain the data are briefly described. General indications on how to use the data to obtain the internal pressure versus time for a payload, its self-contamination, the gaseous flow in its vicinity, the column densities in its field of view, and other environmental parameters which are dependent on the outgassing of a payload are provided.

  3. Public open space characteristics influencing adolescents' use and physical activity: A systematic literature review of qualitative and quantitative studies.

    Science.gov (United States)

    Van Hecke, Linde; Ghekiere, Ariane; Veitch, Jenny; Van Dyck, Delfien; Van Cauwenberg, Jelle; Clarys, Peter; Deforche, Benedicte

    2018-04-06

    The objective of this systematic review was to provide insight into the specific characteristics of public open spaces (POS) associated with adolescents' POS visitation and physical activity (PA). Qualitative research suggests many characteristics to be associated with POS visitation and PA. Quantitative evidence confirmed a positive association between presence of trails, playgrounds and specific types of sports fields (e.g. basketball) with POS visitation and PA, whereas safety and aesthetics seemed subordinate. Suggestions for future research, as well as some methodological recommendations are provided. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Surface Displacement Field of a Coated Elastic Half-Space Under the Influence of a Moving Distributional Load

    Directory of Open Access Journals (Sweden)

    Onur Şahin

    2017-04-01

    Full Text Available An analysis of the distributed moving load along the surface of a coated half space is presented. The formulation of the problem depends on the hyperbolic-elliptic asymptotic model developed earlier by the authors. The integral solution of the longitudinal and transverse displacements along the surface for the sub and super-Rayleigh cases are obtained by using the uniform stationary phase method. Numerical comparisons of the exact and asymptotic solutions of the longitudinal displacement are illustrated for the certain cross-sections of the profile.

  5. The influence of different space-related physiological variations on exercise capacity determined by oxygen uptake kinetics

    Science.gov (United States)

    Stegemann, J.

    Oxygen uptake kinetics, following defined variations of work load changes allow to estimate the contribution of aerob and anaerob energy supply which is the base for determining work capacity. Under the aspect of long duration missions with application of adequate dosed countermeasures, a reliable estimate of the astronaut's work capacity is important to adjust the necessary inflight training. Since the kinetics of oxygen uptake originate in the working muscle group itself, while measurements are performed at the mouth, various influences within the oxygen transport system might disturb the determinations. There are not only detraining effects but also well-known other influences, such as blood- and fluid shifts induced by weightlessness. They might have an impact on the circulatory system. Some of these factors have been simulated by immersion, blood donation, and changing of the body position.

  6. Habitat quality influences population distribution, individual space use and functional responses in habitat selection by a large herbivore.

    Science.gov (United States)

    Bjørneraas, Kari; Herfindal, Ivar; Solberg, Erling Johan; Sæther, Bernt-Erik; van Moorter, Bram; Rolandsen, Christer Moe

    2012-01-01

    Identifying factors shaping variation in resource selection is central for our understanding of the behaviour and distribution of animals. We examined summer habitat selection and space use by 108 Global Positioning System (GPS)-collared moose in Norway in relation to sex, reproductive status, habitat quality, and availability. Moose selected habitat types based on a combination of forage quality and availability of suitable habitat types. Selection of protective cover was strongest for reproducing females, likely reflecting the need to protect young. Males showed strong selection for habitat types with high quality forage, possibly due to higher energy requirements. Selection for preferred habitat types providing food and cover was a positive function of their availability within home ranges (i.e. not proportional use) indicating functional response in habitat selection. This relationship was not found for unproductive habitat types. Moreover, home ranges with high cover of unproductive habitat types were larger, and smaller home ranges contained higher proportions of the most preferred habitat type. The distribution of moose within the study area was partly related to the distribution of different habitat types. Our study shows how distribution and availability of habitat types providing cover and high-quality food shape ungulate habitat selection and space use.

  7. The influence of pore-fluid in the soil on ground vibrations from a tunnel embedded in a layered half-space

    Science.gov (United States)

    Yuan, Zonghao; Cao, Zhigang; Boström, Anders; Cai, Yuanqiang

    2018-04-01

    A computationally efficient semi-analytical solution for ground-borne vibrations from underground railways is proposed and used to investigate the influence of hydraulic boundary conditions at the scattering surfaces and the moving ground water table on ground vibrations. The arrangement of a dry soil layer with varying thickness resting on a saturated poroelastic half-space, which includes a circular tunnel subject to a harmonic load at the tunnel invert, creates the scenario of a moving water table for research purposes in this paper. The tunnel is modelled as a hollow cylinder, which is made of viscoelastic material and buried in the half-space below the ground water table. The wave field in the dry soil layer consists of up-going and down-going waves while the wave field in the tunnel wall consists of outgoing and regular cylindrical waves. The complete solution for the saturated half-space with a cylindrical hole is composed of down-going plane waves and outgoing cylindrical waves. By adopting traction-free boundary conditions on the ground surface and continuity conditions at the interfaces of the two soil layers and of the tunnel and the surrounding soil, a set of algebraic equations can be obtained and solved in the transformed domain. Numerical results show that the moving ground water table can cause an uncertainty of up to 20 dB for surface vibrations.

  8. Investigating the Influence of Light Shelf Geometry Parameters on Daylight Performance and Visual Comfort, a Case Study of Educational Space in Tehran, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Moazzeni

    2016-07-01

    Full Text Available Daylight can be considered as one of the most important principles of sustainable architecture. It is unfortunate that this is neglected by designers in Tehran, a city that benefits from a significant amount of daylight and many clear sunny days during the year. Using a daylight controller system increases space natural light quality and decreases building lighting consumption by 60%. It also affects building thermal behavior, because most of them operate as shading. The light shelf is one of the passive systems for controlling daylight, mostly used with shading and installed in the upper half of the windows above eye level. The influence of light shelf parameters, such as its dimensions, shelf rotation angle and orientation on daylight efficiency and visual comfort in educational spaces is investigated in this article. Daylight simulation software and annual analysis based on climate information during space occupation hours were used. The results show that light shelf dimensions, as well as different orientations, especially in southern part, are influential in the distribution of natural light and visual comfort. At the southern orientation, increased light shelf dimensions result in an increase of the area of the work plane with suitable daylight levels by 2%–40% and a significant decrease in disturbing and intolerable glare hours.

  9. Quantum evolution across singularities

    International Nuclear Information System (INIS)

    Craps, Ben; Evnin, Oleg

    2008-01-01

    Attempts to consider evolution across space-time singularities often lead to quantum systems with time-dependent Hamiltonians developing an isolated singularity as a function of time. Examples include matrix theory in certain singular time-dependent backgounds and free quantum fields on the two-dimensional compactified Milne universe. Due to the presence of the singularities in the time dependence, the conventional quantum-mechanical evolution is not well-defined for such systems. We propose a natural way, mathematically analogous to renormalization in conventional quantum field theory, to construct unitary quantum evolution across the singularity. We carry out this procedure explicitly for free fields on the compactified Milne universe and compare our results with the matching conditions considered in earlier work (which were based on the covering Minkowski space)

  10. Influence of smoking and obesity on alveolar-arterial gas pressure differences and dead space ventilation at rest and peak exercise in healthy men and women.

    Science.gov (United States)

    Gläser, Sven; Ittermann, Till; Koch, Beate; Schäper, Christoph; Felix, Stephan B; Völzke, Henry; Könemann, Raik; Ewert, Ralf; Hansen, James E

    2013-06-01

    Besides exercise intolerance, the assessment of ventilatory and perfusion adequacy allows additional insights in the disease pathophysiology in many cardiovascular or pulmonary diseases. Valid measurements of dead space/tidal volume ratios (VD/VT), arterial (a') - end-tidal (et) carbon dioxide (CO2) and oxygen (O2) pressure differences (p(a'-et)CO2) and (p(et-a')O2), and alveolar (A)-a' O2 pressure differences (p(A-a')O2) require using blood samples in addition to gas exchange analyses on a breath-by-breath-basis. Smoking and nutritional status are also important factors in defining disorders. Using a large healthy population we considered the impact of these factors to develop useful prediction equations. Incremental cycle exercise protocols were applied to apparently healthy volunteer adults who did not have structural heart disease or echocardiographic or lung function pathologies. Age, height, weight, and smoking were analysed for their influence on the target parameters in each gender. Reference values were determined by regression analyses. The final study sample consisted of 476 volunteers (190 female), aged 25-85 years. Smoking significantly influences p(A-a')O2 and p(a'-et)CO2 at rest and peak exercise, and VD/VT during exercise. Obesity influences upper limits of VD/VT, p(a'-et)CO2 and p(et-a')O2 at rest as well as p(A-a')O2 and p(et-a')O2 at exercise. Reference equations for never-smokers as well as for apparently healthy smokers considering influencing factors are given. Gender, age, height, weight, and smoking significantly influence gas exchange. Considering all of these factors this study provides a comprehensive set of reference equations derived from a large number of participants of a population-based study. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. BIOGAS PLANT AS AN ELEMENT THAT HAS A POSITIVE INFLUENCE ON THE ENVIRONMENTAL CHANGES OF RURAL SPACE

    Directory of Open Access Journals (Sweden)

    Wojciech Pawłowski

    2017-10-01

    Full Text Available In the contemporary rural landscape, an agricultural biogas plant is becoming an increasingly frequent element of agricultural installations. There is a need to ask an important question: is a new technology, such as biogas plants with medium power of 1MW, listed as investments which can have significant environmental impacts? This question is becoming an integral part of rural space as a new form of village buildings. The inevitable changes in the rural landscape and the way of carrying out farming have both a positive and negative impact on the rural environment. Biogas plants, as new objects in developing country industries, are undoubtedly an important element in the way of obtaining green energy. Location is the most important factor for the success of the establishment and operation of the biogas plant, which is important not only for economic reasons, but also socio-environmental and landscape reasons.

  12. Managing the urban commons: the relative influence of individual and social incentives on the treatment of public space.

    Science.gov (United States)

    O'Brien, Daniel Tumminelli

    2012-12-01

    All communities have common resources that are vulnerable to selfish motives. The current paper explores this challenge in the specific case of the urban commons, defined as the public spaces and scenery of city neighborhoods. A theoretical model differentiates between individual incentives and social incentives for caring for the commons. The quality of a commons is defined as the level of physical (e.g., loose garbage) and social (e.g., public disturbances) disorder. A first study compared levels of disorder across the census block groups of a single city; the second compared the disorder generated by individual addresses in two neighborhoods. Each study found that homeownership, an individual incentive, was the main predictor of disorder. Owner-occupied parcels generated less disorder than their renter-occupied neighbors, but both parcel types produced less disorder in a neighborhood with greater homeownership. The results emphasize the need for considering both individual and social incentives for group-beneficial behaviors.

  13. MoMa: From Molecules to Man: Space Research Applied to the improvement of the Quality of Life of the Ageing Population on Earth. Evolution of a project

    Science.gov (United States)

    Zambito, Anna Maria; Curcio, Francesco; Meli, Antonella; Saverio Ambesi-Impiombato, Francesco

    The "MoMa" project: "From Molecules to Man: Space Research Applied to the improvement of the Quality of Life of the Ageing Population on Earth started June 16 2006 and finished right on schedule June 25 2009, has been the biggest of the three projects funded by ASI in the sector "Medicine and Biotechnology. In the last years the scientific community had formed a national chain of biomedical spatial research with different research areas. MoMa responds to the necessity of unification in ASI of the two areas "Radiobiology and Protection" and "Cellular and Molecular Biotechnology" in a line of joint research: "Biotechnological Applications" were the interests of all groups would be combined and unified in a goal of social relevance. MoMa is the largest project ever developed in the biomedical area in Italy, the idea was born thinking about the phenomenon of acceleration of the aging process observed in space, and already described in literature, and the aim of studying the effects of the space environment at cellular, molecular and human organism level. "MoMa" was divided into three primary areas of study: Molecules, Cells and Man with an industrial area alongside. This allowed to optimize the work and information flows within the scientific research more similar and more culturally homogeneous and allowed a perfect industrial integration in a project of great scientific importance. Within three scientific areas 10 scientific lines in total are identified, each of them coordinated by a subcontractor. The rapid and efficient exchange of information between different areas of science and the development of industrial applications in various areas of interest have been assured by a strong work of Scientific Coordination of System Engineering and Quality Control. After three years of intense and coordinated activities within the MoMa project, the objectives achieved are very significant not only as regards the scientific results and the important hardware produced but

  14. Space-time evolution of the power absorbed by creating and heating a hydrogen plasma column by a pulsed laser beam

    International Nuclear Information System (INIS)

    Pincosy, Philip; Dufresne, Daniel; Bournot, Philippe; Caressa, J.-P.; Autric, Michel

    1976-01-01

    Space-time measurements of light intensity are presented for the analysis of the processes involved in the creation and heating of an under-dense hydrogen plasma column by a pulsed CO 2 laser beam. The laser beam trapping due to the rapid development of a radial electron density gradient is specifically demonstrated. Time measurements of the changes in the laser power longitudinally transmitted through the plasma give evidence for a significant absorption of the incident power during the first 150 nanoseconds of the interaction [fr

  15. The influence of stream bed geomorphology on chemical species within the hyporheic zone over time and space

    Science.gov (United States)

    Quick, A. M.; Reeder, W. J.; Farrell, T. B.; Benner, S. G.; Tonina, D.; Feris, K. P.

    2017-12-01

    The hyporheic zone is well established as an important zone of biogeochemical activity in streams and rivers. Multiple large scale flume experiments were carried out to mimic bedform-controlled hyporheic zones in small streams. The laboratory setting allowed for geochemical measurement resolution and replicates that would not be possible in a natural setting. Two flume experiments that consisted of three small streams with variable sizes of bedform dunes were carried out in which chemical species were measured in the surface water and along hyporheic flow lines in the subsurface. The species measured included dissolved oxygen, pH, alkalinity, major cations (Na+, Mg2+, Ca2+, K+, Si4+, Al3+), anions (NO3-, NO2-, SO42-, PO43-, Cl-), and many trace elements (As, Sr, Co, Ni, Cu, Zn, Pb, U, V). Observed spatial and temporal trends reflect microbiological processes, changing redox conditions, and chemical weathering. In general, microbial respiration causes DO to decrease with residence time, leading to aerobic and anaerobic zones that influence redox-sensitive species and pH gradients that influence mineral solubility. Most other species concentrations, including those of major cations and trace elements, increase with residence time and generally decrease over time elapsed during the experiment. The different dune morphologies dictate flow velocities in the hyporheic zone; for most species, steeper dunes with higher velocities had lower concentrations at the end of the experiment, indicating the role of dune shape in the weathering rates of minerals in hyporheic sediment and the concentrations of dissolved species entering the surface water over time. Many of the observed trends can be applied, at least qualitatively, to understanding how these species will behave in natural settings. This insight will contribute to the understanding of many of the applications of the hyporheic zone (e.g. bioremediation, habitat, greenhouse gas emissions, etc.).

  16. The influence of interdisciplinary collaboration on decision making: a framework to analyse stakeholder coalitions, evolution and learning in strategic delta planning

    Science.gov (United States)

    Vermoolen, Myrthe; Hermans, Leon

    2015-04-01

    The sustained development of urbanizing deltas requires that conflicting interests are reconciled, in an environment characterized by technical complexity and knowledge limitations. However, integrating ideas and establishing cooperation between actors with different backgrounds and roles still proves a challenge. Agreeing on strategic choices is difficult and implementation of agreed plans may lead to unanticipated and unintended outcomes. How can individual disciplinary perspectives come together and establish a broadly-supported and well-informed plan, the implementation of which contributes to sustainable delta development? The growing recognition of this need to bring together different stakeholders and different disciplinary perspectives runs parallel to a paradigm shift from 'hard' hydrological engineering to multi-functional and more 'soft' hydrological engineering in water management. As a result, there is now more attention for interdisciplinary collaboration that not only takes the physical characteristics of water systems into account, but also the interaction between physical and societal components of these systems. Thus, it is important to study interdisciplinary collaboration and how this influences decision-making. Our research looks into this connection, using a case in delta planning in the Netherlands, where there have been several (attempts for) integration of spatial planning and flood risk/ water management, e.g. in the case of the Dutch Delta Programme. This means that spatial designers and their designs play an important role in the strategic delta planning process as well, next to civil engineers, etc. This study explores the roles of stakeholders, experts and policy makers in interdisciplinary decision-making in dynamic delta planning processes, using theories and methods that focus on coalitions, learning and changes over time in policy and planning processes. This requires an expansion of the existing frameworks to study

  17. Influence of gestational age on dead space and alveolar ventilation in preterm infants ventilated with volume guarantee.

    Science.gov (United States)

    Neumann, Roland P; Pillow, Jane J; Thamrin, Cindy; Larcombe, Alexander N; Hall, Graham L; Schulzke, Sven M

    2015-01-01

    Ventilated preterm infant lungs are vulnerable to overdistension and underinflation. The optimal ventilator-delivered tidal volume (VT) in these infants is unknown and may depend on the extent of alveolarisation at birth. We aimed to calculate respiratory dead space (VD) from the molar mass (MM) signal of an ultrasonic flowmeter (VD,MM) in very preterm infants on volume-targeted ventilation (VT target, 4-5 ml/kg) and to study the association between gestational age (GA) and VD,MM-to-VT ratio (VD,MM/VT), alveolar tidal volume (VA) and alveolar minute volume (AMV). This was a single-centre, prospective, observational, cohort study in a neonatal intensive care unit. Tidal breathing analysis was performed in ventilated very preterm infants (GA range 23-32 weeks) on day 1 of life. Valid measurements were obtained in 43/51 (87%) infants. Tidal breathing variables were analysed using multivariable linear regression. VD,MM/VT was negatively associated with GA after adjusting for birth weight Z score (p volume guarantee setting of 4-5 ml/kg in the Dräger Babylog® 8000 plus ventilator may be inappropriate as a universal target across the GA range of 23-32 weeks. Differences between measured and set VT and the dependence of this difference on GA require further investigation. © 2014 S. Karger AG, Basel.

  18. Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation

    International Nuclear Information System (INIS)

    Piattella, O.F.; Rodrigues, D.C.; Fabris, J.C.; Pacheco, J.A. de Freitas

    2013-01-01

    We discuss solutions of Vlasov-Einstein equation for collisionless dark matter particles in the context of a flat Friedmann universe. We show that, after decoupling from the primordial plasma, the dark matter phase-space density indicator Q = ρ/(σ 1D 2 ) 3/2 remains constant during the expansion of the universe, prior to structure formation. This well known result is valid for non-relativistic particles and is not ''observer dependent'' as in solutions derived from the Vlasov-Poisson system. In the linear regime, the inclusion of velocity dispersion effects permits to define a physical Jeans length for collisionless matter as function of the primordial phase-space density indicator: λ J = (5π/G) 1/2 Q −1/3 ρ dm −1/6 . The comoving Jeans wavenumber at matter-radiation equality is smaller by a factor of 2-3 than the comoving wavenumber due to free-streaming, contributing to the cut-off of the density fluctuation power spectrum at the lowest scales. We discuss the physical differences between these two scales. For dark matter particles of mass equal to 200 GeV, the derived Jeans mass is 4.3 × 10 −6 M ⊙

  19. Isotopic and chemical composition of groundwater in the Bolivian Altiplano, present space evolution records hydrologic conditions since 11,000 Yr

    International Nuclear Information System (INIS)

    Coudrain, A.; Talbi, A.; Loubet, M.; Gallaire, R.; Jusserand, C.; Ramirez, E.; Ledoux, E.

    1999-01-01

    The phreatic aquifer of the central Altiplano shows a Cl concentration that increases from 0.5 meq l -1 upstream to 150 meq l -1 downstream. The main outflow process from the aquifer is the upward flow E into the unsaturated zone associated to evaporation close to soil surface. A relation has been established for any arid zone areas on the base of isotopic profiles: E (mm yr -1 ) = 63 Z -1.5 where Z (m) is the water table depth under soil surface. The aquifer under study may have acquired its high chlorine content during last lacustrine phase (Tauca, 12 ka BP). Arguments for this hypothesis are: (i) maximum level of the lake (3780 m) higher than present soil elevation in the area, (ii) same order of salinity in the paleolake and in the more saline groundwater, (iii) weak molar ratio of Li/Cl in saline groundwater and in the Tauca, (iv) modelling of Cl transport over 11,000 years consistent with observed spatial evolution of Cl in groundwater. To this scenario, might be superimposed the assumption of a delay for the convective transfer of salt towards south by the coupled effects of accumulation of salt in the unsaturated zone by evaporation from the aquifer during thousand or so years, and of the subsequent return of this salt downwards to the aquifer during some short rainy periods. The 87 Sr/ 86 Sr, major and trace element compositions of surface and groundwater support this proposed scenario. (author)

  20. Time-space distribution of laser-induced plasma parameters and its influence on emission spectra of the laser plumes

    International Nuclear Information System (INIS)

    Ershov-Pavlov, E.A.; Katsalap, K.Yu.; Stepanov, K.L.; Stankevich, Yu.A.

    2008-01-01

    A physical model is developed accounting for dynamics and radiation of plasma plumes induced by nanosecond laser pulses on surface of solid samples. The model has been applied to simulate emission spectra of the laser erosion plasma at the elemental analysis of metals using single- and double-pulse excitation modes. Dynamics of the sample heating and expansion of the erosion products are accounted for by the thermal conductivity and gas dynamic equations, respectively, supposing axial symmetry. Using the resulting time-space distributions of the plasma parameters, emission spectra of the laser plumes are evaluated by solving the radiation transfer equation. Particle concentration in consecutive ionization stages is described by the Saha equation in the Debye approximation. The population of excited levels is determined according to Boltzmann distribution. Local characteristics determining spectral emission and absorption coefficients are obtained point-by-point along an observation line. Voigt spectral line profiles are considered with main broadening mechanisms taken into account. The plasma dynamics and plume emission spectra have been studied experimentally and by the model. A Q-switched Nd:YAG laser at 1064 nm wavelength has been used to irradiate Al sample with the pulses of 15 ns and 50 mJ duration and energy, respectively. It has resulted in maximum power density of 0.8 MW/cm 2 on the sample surface. The laser plume emission spectra have been recorded at a side-on observation. Problems of the spectra contrast and of the elemental analysis efficiency are considered relying on a comparative study of the measurement and simulation results at the both excitation modes

  1. Adaptive social learning strategies in temporally and spatially varying environments : how temporal vs. spatial variation, number of cultural traits, and costs of learning influence the evolution of conformist-biased transmission, payoff-biased transmission, and individual learning.

    Science.gov (United States)

    Nakahashi, Wataru; Wakano, Joe Yuichiro; Henrich, Joseph

    2012-12-01

    Long before the origins of agriculture human ancestors had expanded across the globe into an immense variety of environments, from Australian deserts to Siberian tundra. Survival in these environments did not principally depend on genetic adaptations, but instead on evolved learning strategies that permitted the assembly of locally adaptive behavioral repertoires. To develop hypotheses about these learning strategies, we have modeled the evolution of learning strategies to assess what conditions and constraints favor which kinds of strategies. To build on prior work, we focus on clarifying how spatial variability, temporal variability, and the number of cultural traits influence the evolution of four types of strategies: (1) individual learning, (2) unbiased social learning, (3) payoff-biased social learning, and (4) conformist transmission. Using a combination of analytic and simulation methods, we show that spatial-but not temporal-variation strongly favors the emergence of conformist transmission. This effect intensifies when migration rates are relatively high and individual learning is costly. We also show that increasing the number of cultural traits above two favors the evolution of conformist transmission, which suggests that the assumption of only two traits in many models has been conservative. We close by discussing how (1) spatial variability represents only one way of introducing the low-level, nonadaptive phenotypic trait variation that so favors conformist transmission, the other obvious way being learning errors, and (2) our findings apply to the evolution of conformist transmission in social interactions. Throughout we emphasize how our models generate empirical predictions suitable for laboratory testing.

  2. Laser-induced breakdown spectroscopy for space exploration applications: Influence of the ambient pressure on the calibration curves prepared from soil and clay samples

    International Nuclear Information System (INIS)

    Salle, Beatrice; Cremers, David A.; Maurice, Sylvestre; Wiens, Roger C.

    2005-01-01

    Recently, there has been an increasing interest in the laser-induced breakdown spectroscopy (LIBS) technique for stand-off detection of geological samples for use on landers and rovers to Mars, and for other space applications. For space missions, LIBS analysis capabilities must be investigated and instrumental development is required to take into account constraints such as size, weight, power and the effect of environmental atmosphere (pressure and ambient gas) on flight instrument performance. In this paper, we study the in-situ LIBS method at reduced pressure (7 Torr CO 2 to simulate the Martian atmosphere) and near vacuum (50 mTorr in air to begin to simulate the Moon or asteroids' pressure) as well as at atmospheric pressure in air (for Earth conditions and comparison). Here in-situ corresponds to distances on the order of 150 mm in contrast to stand-off analysis at distance of many meters. We show the influence of the ambient pressure on the calibration curves prepared from certified soil and clay pellets. In order to detect simultaneously all the elements commonly observed in terrestrial soils, we used an Echelle spectrograph. The results are discussed in terms of calibration curves, measurement precision, plasma light collection system efficiency and matrix effects

  3. Influence of dust particles on the neon spectral line intensities at the uniform positive column of dc discharge at the space apparatus “Plasma Kristall-4”

    Science.gov (United States)

    Usachev, A. D.; Zobnin, A. V.; Shonenkov, A. V.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.; Pustyl'nik, M. Y.; Fink, M. A.; Thoma, M. A.; Thomas, H. M.; Padalka, G. I.

    2018-01-01

    Influence of the elongated dust cloud on the intensities of different neon spectral lines in visible and near ir spectral ranges in the uniform positive column has been experimentally investigated using the Russian-European space apparatus “Plasma Kristall-4” (SA PK-4) on board of the International Space Station (ISS). The investigation was performed in the low pressure (0.5 mbar) direct current (dc, 1 mA) gas discharge in neon. Microgravity allowed us to perform experiments with a large dust cloud in the steady-state regime. To avoid the dust cloud drift in the dc electric field a switching dc polarity discharge mode has been applied. During the experiment a dust cloud of 9 mm in diameter in the discharge tube of 30 mm in diameter with the length of about 100 mm has been observed in the steady-state regime. In this regard, the intensities of neon spectral lines corresponding to 3p → 3s electronic transitions have increased by a factor of 1.4 times, while the intensities of neon spectral lines corresponding to 3d → 3p electronic transitions have increased by a factor of 1.6 times. The observed phenomenon is explained on the basis of the Schottky approach by a self-consistent rising dc electric field in the dusty plasma cloud resulting in an increase of the electron temperature.

  4. Evolution of subsidiary competences

    DEFF Research Database (Denmark)

    Geisler Asmussen, Christian; Pedersen, Torben; Dhanaraj, Charles

    of competitive advantage of nations, we hypothesize the contingencies under which heterogeneity in host environments influences subsidiary competence configuration. We test our model with data from more than 2,000 subsidiaries in seven Western European countries. Our results provide new insights on the evolution...

  5. Darwinism: Evolution or Revolution?

    Science.gov (United States)

    Holt, Niles R.

    1989-01-01

    Maintains that Darwin's theory of evolution was more than a science versus religion debate; rather it was a revolutionary concept that influenced numerous social and political ideologies and movements throughout western history. Traces the impact of Darwin's work historically, utilizing a holistic approach. (RW)

  6. The theory of evolution

    Directory of Open Access Journals (Sweden)

    Oleg Bazaluk

    2015-06-01

    Full Text Available The book The Theory of Evolution: from the Space Vacuum to Neural Ensembles and Moving Forward, an edition of 100 copies, was published in Russian language, in December 2014 in Kiev. Its Russian version is here: http://en.bazaluk.com/journals.html. Introduction, Chapter 10 and Conclusion published in English for the first time. Since 2004 author have been researching in the field of theory of Evolution, Big History. The book was written on the base of analysis of more than 2000 primary sources of this research topic. The volume is 90,000 words (with Reference. The book is for a wide range of professionals, from students to professors and researchers working in the fields of: philosophical anthropology, philosophy, Big History, cosmology, biology, neuroscience and etc. In the book, the author defines the evolution as continuous and nonlinear complication of the structure of matter, the types of interaction and environments; analyzes existing in modern science and philosophy approaches to the research of the process of evolution, degree of development of the factors and causes of evolution. Unifying interdisciplinary researches of evolution in cosmology, biology, neuroscience and philosophy, the author presents his vision of the model of «Evolving Matter», which allows us to consider not only the laws of transition of space vacuum in neural ensembles but also to see our Universe as a complication, heterogeneous organization. Interdisciplinary amount of information on the theory of evolution is systematized and a new method of world perception is proposed in the book.

  7. Evolution of the specific-heat anomaly of the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7} under the influence of doping through application of pressure up to 10 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Lortz, Rolf [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland); Junod, Alain [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland); Jaccard, Didier [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland); Wang, Yuxing [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland); Meingast, Christoph [Forschungszentrum Karlsruhe, Institut fuer Festkoerperphysik, 76021 Karlsruhe (Germany); Masui, Takahiko [Superconductivity Research Laboratory-ISTEC, 10-13 Shinonome I-Chome, Koto-ku, Tokyo 135 (Japan); Tajima, Setsuko [Superconductivity Research Laboratory-ISTEC, 10-13 Shinonome I-Chome, Koto-ku, Tokyo 135 (Japan)

    2005-07-06

    The evolution of the specific-heat anomaly in the overdoped range of a single crystal of the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7} has been studied under the influence of pressure up to 10 GPa, using AC calorimetry in a Bridgman-type pressure cell. We show that the specific-heat jump as well as the bulk T{sub c} are reduced with increasing pressure in accordance with a simple charge-transfer model. This new method enables us through pressure-induced charge transfer to study the doping dependence of the superconducting transition, as well as the evolution of the superconducting condensation energy on a single stoichiometric sample without adding atomic disorder.

  8. Evolution of the specific-heat anomaly of the high-temperature superconductor YBa2Cu3O7 under the influence of doping through application of pressure up to 10 GPa

    International Nuclear Information System (INIS)

    Lortz, Rolf; Junod, Alain; Jaccard, Didier; Wang, Yuxing; Meingast, Christoph; Masui, Takahiko; Tajima, Setsuko

    2005-01-01

    The evolution of the specific-heat anomaly in the overdoped range of a single crystal of the high-temperature superconductor YBa 2 Cu 3 O 7 has been studied under the influence of pressure up to 10 GPa, using AC calorimetry in a Bridgman-type pressure cell. We show that the specific-heat jump as well as the bulk T c are reduced with increasing pressure in accordance with a simple charge-transfer model. This new method enables us through pressure-induced charge transfer to study the doping dependence of the superconducting transition, as well as the evolution of the superconducting condensation energy on a single stoichiometric sample without adding atomic disorder

  9. The physics of evolution

    Science.gov (United States)

    Eigen, Manfred

    1988-12-01

    The Darwinian concept of evolution through natural selection has been revised and put on a solid physical basis, in a form which applies to self-replicable macromolecules. Two new concepts are introduced: sequence space and quasi-species. Evolutionary change in the DNA- or RNA-sequence of a gene can be mapped as a trajectory in a sequence space of dimension ν, where ν corresponds to the number of changeable positions in the genomic sequence. Emphasis, however, is shifted from the single surviving wildtype, a single point in the sequence space, to the complex structure of the mutant distribution that constitutes the quasi-species. Selection is equivalent to an establishment of the quasi-species in a localized region of sequence space, subject to threshold conditions for the error rate and sequence length. Arrival of a new mutant may violate the local threshold condition and thereby lead to a displacement of the quasi-species into a different region of sequence space. This transformation is similar to a phase transition; the dynamical equations that describe the quase-species have been shown to be analogous to those of the two-dimensional Ising model of ferromagnetism. The occurrence of a selectively advantageous mutant is biased by the particulars of the quasi-species distribution, whose mutants are populated according to their fitness relative to that of the wild-type. Inasmuch as fitness regions are connected (like mountain ridges) the evolutionary trajectory is guided to regions of optimal fitness. Evolution experiments in test tubes confirm this modification of the simple chance and law nature of the Darwinian concept. The results of the theory can also be applied to the construction of a machine that provides optimal conditions for a rapid evolution of functionally active macromolecules. An introduction to the physics of molecular evolution by the author has appeared recently.1 Detailed studies of the kinetics and mechanisms of replication of RNA, the most

  10. From 3D to 2D Co and Ni Oxyhydroxide Catalysts: Elucidation of the Active Site and Influence of Doping on the Oxygen Evolution Activity

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Hansen, Heine Anton; Vegge, Tejs

    2017-01-01

    Layered oxyhydroxides (ox-hys) of Ni and Co are among the most active catalysts for oxygen evolution in alkaline media. Their activities can be further tuned by delamination into single-layer oxide sheets or by means of doping. The active site for the reaction and how doping and delamination...... investigate the role of terrace and edge sites and use stability, catalytic activity, and electronic conductivity as evaluation criteria to pinpoint the best catalysts. We arrive at several important conclusions: the ox-hy surface is fully oxidized under oxygen evolution conditions, bulk terraces...

  11. d-Amino acids in molecular evolution in space - Absolute asymmetric photolysis and synthesis of amino acids by circularly polarized light.

    Science.gov (United States)

    Sugahara, Haruna; Meinert, Cornelia; Nahon, Laurent; Jones, Nykola C; Hoffmann, Søren V; Hamase, Kenji; Takano, Yoshinori; Meierhenrich, Uwe J

    2018-07-01

    Living organisms on the Earth almost exclusively use l-amino acids for the molecular architecture of proteins. The biological occurrence of d-amino acids is rare, although their functions in various organisms are being gradually understood. A possible explanation for the origin of biomolecular homochirality is the delivery of enantioenriched molecules via extraterrestrial bodies, such as asteroids and comets on early Earth. For the asymmetric formation of amino acids and their precursor molecules in interstellar environments, the interaction with circularly polarized photons is considered to have played a potential role in causing chiral asymmetry. In this review, we summarize recent progress in the investigation of chirality transfer from chiral photons to amino acids involving the two major processes of asymmetric photolysis and asymmetric synthesis. We will discuss analytical data on cometary and meteoritic amino acids and their potential impact delivery to the early Earth. The ongoing and future ambitious space missions, Hayabusa2, OSIRIS-REx, ExoMars 2020, and MMX, are scheduled to provide new insights into the chirality of extraterrestrial organic molecules and their potential relation to the terrestrial homochirality. This article is part of a Special Issue entitled: d-Amino acids: biology in the mirror, edited by Dr. Loredano Pollegioni, Dr. Jean-Pierre Mothet and Dr. Molla Gianluca. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Space Biology and Medicine. Volume I; Space and Its Exploration

    Science.gov (United States)

    Nicogossian, Arnauld E.; Mohler, Stanley R.; Gazenko, Oleg G.; Grigoryev, Anatoliy I.

    1993-01-01

    and a path to our common future. But for humanity to embark on this path, we need to understand ourselves in a new environment. As such, an understanding of the biological consequences of and opportunities in space flight is essential. In this, the first volume of a joint U.S./Russian series on space biology and medicine, we describe the current status of our understanding of space and present general information that will prove useful when reading subsequent volumes. Since we are witnesses to the beginning of a new era of interplanetary travel, a significant portion of the first volume will concentrate on the physical and ecological conditions that exist in near and outer space, as well as heavenly bodies from the smallest ones to the giant planets and stars. While space exploration is a comparatively recent endeavor, its foundations were laid much more than 30 years ago, and its history has been an eventful one. In the first part of this volume, Rauschenbach, Sokolskiy, and Gurjian address the "Historical Aspects of Space Exploration" from its beginnings to a present-day view of the events of the space age. The nature of space itself and its features is the focus of the second section of the volume. In the first chapter of the part, "Stars and Interstellar Space," the origin and evolution of stars, and the nature of the portions of space most distant from Earth are described by Galeev and Marochnik. In Chapter 2, Pisarenko, Logachev, and Kurt in "The Sun and Interplanetary Space" bring us to the vicinity of our own solar system and provide a description and discussion of the nearest star and its influence on the space environment that our Earth and the other planets inhabit. In our solar system there are many fascinating objects, remnants of the formation of a rather ordinary star in a rather obscure portion of the galaxy. Historical accident has caused us to be much more curious (and knowledgeable) about "The Inner Planets of the Solar System" than about any of

  13. Student Visual Communication of Evolution

    Science.gov (United States)

    Oliveira, Alandeom W.; Cook, Kristin

    2017-06-01

    Despite growing recognition of the importance of visual representations to science education, previous research has given attention mostly to verbal modalities of evolution instruction. Visual aspects of classroom learning of evolution are yet to be systematically examined by science educators. The present study attends to this issue by exploring the types of evolutionary imagery deployed by secondary students. Our visual design analysis revealed that students resorted to two larger categories of images when visually communicating evolution: spatial metaphors (images that provided a spatio-temporal account of human evolution as a metaphorical "walk" across time and space) and symbolic representations ("icons of evolution" such as personal portraits of Charles Darwin that simply evoked evolutionary theory rather than metaphorically conveying its conceptual contents). It is argued that students need opportunities to collaboratively critique evolutionary imagery and to extend their visual perception of evolution beyond dominant images.

  14. Mio-Pliocene to Pleistocene paleotopographic evolution of Brittany (France) from a sequence stratigraphic analysis: relative influence of tectonics and climate

    Science.gov (United States)

    Brault, N.; Bourquin, S.; Guillocheau, F.; Dabard, M.-P.; Bonnet, S.; Courville, P.; Estéoule-Choux, J.; Stepanoff, F.

    2004-01-01

    The Mio-Pliocene in Western Europe is a period of major climatic and tectonic change with important topographic consequences. The aim of this paper is to reconstruct these topographic changes (based on sedimentological analysis and sequence stratigraphy) for the Armorican Massif (western France) and to discuss their significance. The Mio-Pliocene sands of the Armorican Massif (Red Sands) are mainly preserved in paleovalleys and are characterized by extensive fluvial sheetflood deposits with low-preservation and by-pass facies. This sedimentological study shows that the Red Sands correspond to three main sedimentary environments: fluvial (alluvial fan, low-sinuosity rivers and braided rivers), estuarine and some rare open marine deposits (marine bioclastic sands: "faluns" of French authors). Two orders of sequences have been correlated across Brittany with one or two minor A/ S cycles comprised within the retrogradational trend of a major cycle. The unconformity at the base of the lower cycle is more marked than the unconformity observed at the top, which corresponds to a re-incision of the paleovalley network. A comparison of the results of the sequence stratigraphy analysis with eustatic variations and tectonic events during the Mio-Pliocene allows (1) to discuss their influence on the evolution of the Armorican Massif and (2) to compare the stratigraphic record with other west-European basins. The unconformity observed at the base of the first minor cycle may be attributed to Serravallian-Tortonian tectonic activity and/or eustatic fall, and the unconformity of the second minor cycle may be attributed to Late Tortonian-Early Messinian tectonic activity. The earlier unconformity is coeval with the development of a "smooth" paleovalley network compared to the jagged present-day relief. A single episode of Mio-Pliocene deformation recorded in Brittany may be dated as Zanclean, thus explaining the lack of the maximum flooding surface except in isolated areas. From

  15. Schumpeter's Evolution

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    reworking of his basic theory of economic evolution in Development from 1934, and this reworking was continued in Cycles from 1939. Here Schumpeter also tried to handle the statistical and historical evidence on the waveform evolution of the capitalist economy. Capitalism from 1942 modified the model...

  16. Galactic evolution

    International Nuclear Information System (INIS)

    Pagel, B.

    1979-01-01

    Ideas are considered concerning the evolution of galaxies which are closely related to those of stellar evolution and the origin of elements. Using information obtained from stellar spectra, astronomers are now able to consider an underlying process to explain the distribution of various elements in the stars, gas and dust clouds of the galaxies. (U.K.)