WorldWideScience

Sample records for atomic environments implications

  1. PubChem atom environments.

    Science.gov (United States)

    Hähnke, Volker D; Bolton, Evan E; Bryant, Stephen H

    2015-01-01

    Atom environments and fragments find wide-spread use in chemical information and cheminformatics. They are the basis of prediction models, an integral part in similarity searching, and employed in structure search techniques. Most of these methods were developed and evaluated on the relatively small sets of chemical structures available at the time. An analysis of fragment distributions representative of most known chemical structures was published in the 1970s using the Chemical Abstracts Service data system. More recently, advances in automated synthesis of chemicals allow millions of chemicals to be synthesized by a single organization. In addition, open chemical databases are readily available containing tens of millions of chemical structures from a multitude of data sources, including chemical vendors, patents, and the scientific literature, making it possible for scientists to readily access most known chemical structures. With this availability of information, one can now address interesting questions, such as: what chemical fragments are known today? How do these fragments compare to earlier studies? How unique are chemical fragments found in chemical structures? For our analysis, after hydrogen suppression, atoms were characterized by atomic number, formal charge, implicit hydrogen count, explicit degree (number of neighbors), valence (bond order sum), and aromaticity. Bonds were differentiated as single, double, triple or aromatic bonds. Atom environments were created in a circular manner focused on a central atom with radii from 0 (atom types) up to 3 (representative of ECFP_6 fragments). In total, combining atom types and atom environments that include up to three spheres of nearest neighbors, our investigation identified 28,462,319 unique fragments in the 46 million structures found in the PubChem Compound database as of January 2013. We could identify several factors inflating the number of environments involving transition metals, with many

  2. Resonant interaction modified by the atomic environment

    International Nuclear Information System (INIS)

    Sainz, I; Klimov, A B; Chumakov, S M

    2003-01-01

    The dynamics of a resonant atom interacting with a quantum cavity field in the presence of many off-resonant atoms is studied. In the framework of the effective Hamiltonian approach we show that the results of elimination of non-resonant transitions are (a) a dynamical Stark shift of the field frequency, dependent on the populations of non-resonant atoms, (b) dependence of the coupling constant between the resonant atom and the field on the populations of non-resonant atoms, and (c) an effective dipole-dipole interaction between non-resonant atoms. Two effects (the coherent influence and dephasing) of the off-resonant environment on the dynamics of the resonant atom are discussed

  3. AtomPy: an open atomic-data curation environment

    Science.gov (United States)

    Bautista, Manuel; Mendoza, Claudio; Boswell, Josiah S; Ajoku, Chukwuemeka

    2014-06-01

    We present a cloud-computing environment for atomic data curation, networking among atomic data providers and users, teaching-and-learning, and interfacing with spectral modeling software. The system is based on Google-Drive Sheets, Pandas (Python Data Analysis Library) DataFrames, and IPython Notebooks for open community-driven curation of atomic data for scientific and technological applications. The atomic model for each ionic species is contained in a multi-sheet Google-Drive workbook, where the atomic parameters from all known public sources are progressively stored. Metadata (provenance, community discussion, etc.) accompanying every entry in the database are stored through Notebooks. Education tools on the physics of atomic processes as well as their relevance to plasma and spectral modeling are based on IPython Notebooks that integrate written material, images, videos, and active computer-tool workflows. Data processing workflows and collaborative software developments are encouraged and managed through the GitHub social network. Relevant issues this platform intends to address are: (i) data quality by allowing open access to both data producers and users in order to attain completeness, accuracy, consistency, provenance and currentness; (ii) comparisons of different datasets to facilitate accuracy assessment; (iii) downloading to local data structures (i.e. Pandas DataFrames) for further manipulation and analysis by prospective users; and (iv) data preservation by avoiding the discard of outdated sets.

  4. Cold atoms in a cryogenic environment

    International Nuclear Information System (INIS)

    Haslinger, S.

    2011-01-01

    The idea of quantum information processing attracts increasingly interest, where a complex collection of quantum objects and quantum bits are employed to find the ideal building blocks for quantum information systems. Hybrid quantum systems are therefore promising objects as they countervail the particular drawbacks of single quantum objects. Based on superconducting resonator technology, microwave coplanar waveguides provide a well suited interconnection for photons and solid-state quantum bits (qubits), extensively investigated in recent years. Since a quantum memory is presently missing in those electrical accessible circuit cavity quantum devices, connecting the fast processing in a solid sate device to the exceptional long coherence times in atomic ensembles, the presented work is focused to establish the technological foundations for the hybridization of such quantum systems. The microwave photons stored in a superconducting high finesse microwave resonator are therefore an ideal connection between the atom and the solid state quantum world. In the last decade, the miniaturization and integration of quantum optics and atomic physics manipulation techniques on to a single chip was successfully established. Such atom chips are capable of detailed quantum manipulation of ultra-cold atoms and provide a versatile platform to combine the manipulation techniques from atomic physics with the capability of nano-fabrication. In recent years several experiments succeeded in realization of superconducting atom chips in cryogenic environments which opens the road for integrating super-conductive microwave resonators to magnetically couple an atomic ensemble to photons stored in the coplanar high finesse cavity. This thesis presents the concept, design and experimental setup of two approaches to establish an atomic ensemble of rubidium atoms inside a cryogenic environment, based on an Electron beam driven alkali metal atom source for loading a magneto optical trap in a

  5. Atomic environments in iron meteorites using EXAFS

    International Nuclear Information System (INIS)

    Cressey, G.; Dent, A.J.; Dobson, B.; Evans, A.; Greaves, G.N.; Henderson, C.M.B.; Hutchison, R.; Jenkins, R.N.; Thompson, S.P.; Zhu, R.

    1989-01-01

    Extended x ray absorption fine structure (EXAFS) is observed as a modulation on the high energy side of an x ray absorption edge. It occurs when the photo-ejected electron wave is scattered by neighboring atoms in a solid, and interference occurs between the outgoing and scattered waves. The result is that the absorption spectrum carries a signature that is characteristic of the identity and disposition of scattering atoms around the absorbing atom. Therefore, it may be shown that the Fourier transform of the normalized EXAFS can provide detailed information about the immediate environment of specific atoms in a solid and is ideally suited to the study of cosmic dusts. A study of cosmic dust was initiated using EXAFS and other techniques. The simplest type of cosmic material, namely iron meteorites, was investigated

  6. The Atom, the Environment and Sustainable Development

    International Nuclear Information System (INIS)

    2014-09-01

    The IAEA has a broad mandate to facilitate nuclear applications in a number of areas and scientific disciplines. A fundamental component of the Agency's mandate is to enhance the peaceful contribution of nuclear science and technology to the specific development needs of its Member States in areas such as industry, human health, agriculture and nutrition. Nuclear techniques play an important role in addressing these development challenges. By facilitating their use, the IAEA is contributing to sustainable development. Well known examples include helping to advance treatment methods for fighting diseases, improving access to electricity, and increasing food security. A major underlying challenge in development for many Member States is environmental degradation. Environmental issues affect local, national, regional and global communities and threaten to undermine human well-being. Addressing these issues in a timely and efficient manner is essential. As with the other areas mentioned above, nuclear science and technology can make a particularly valuable contribution to assisting with efforts to better understand and protect the natural environment. Through The Atom, the Environment and Sustainable Development, the IAEA aims to raise and widen awareness of the unique contributions nuclear science and technology can make to the environmental dimension of sustainable development. Through this publication and other reports, it is expected that the readers acquire a better and more precise understanding of the significant role of science and technology, including nuclear-related technology, in the global development agenda. This publication also highlights the IAEA's role in supporting developing countries to realize their sustainable development aspirations through technology transfer and capacity-building

  7. Atomic and Molecular Processes in Atmospheric Environments

    Science.gov (United States)

    1971-04-28

    Van der Graaff accelerator through a thin fo.’lo We have calculated the cross section for 7* this process for 0’ ions. This w: 11 provide the... generated curves calculated tor many assumed values of the rate constants. Physical consistency requires two equilibrium constants (hydration n xi...results have generally confirmed the previous results, i.e., with the alkaline earth atoms, charge transfer leaving an atomic ion strongly dominates over

  8. Environment. 1980-1994. International Atomic Energy Agency publications

    International Nuclear Information System (INIS)

    1995-06-01

    The catalogue lists all publications of the International Atomic Energy Agency dealing with the Environment issued during the period 1980-1993. The major subjects covered include: effect of agrochemical residues on soils and aquatic ecosystems, application of radioisotopes in conservation of the environment, siting of nuclear power plants, environmental isotope data and environmental contamination due to nuclear accidents

  9. Intermittent contact atomic force microscopy in electrochemical environment

    Energy Technology Data Exchange (ETDEWEB)

    Haering, P.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegenthaler, H. [Bern Univ., Bern (Switzerland)

    1997-06-01

    In situ measurements with Atomic Force Microscopy may cause surface modifications due to the tip-surface interactions. As an alternative and less destructive method, Intermittent Contact Atomic Force Microscopy (ICAFM) has been tested in an electrolytic environment. In the ICAFM mode the tip is not constantly in contact with the surface under investigation but is tapping onto the surface with a certain frequency. A commercial Park Scientific Instruments Microscopy has been modified to enable in situ experiment with ICAFM. It was possible to image iridium oxide films with ICAFM in the electrolytic environment without any noticeable surface modifications. (author) 3 figs., 4 refs.

  10. Implications of Telecommuting in a Library Environment.

    Science.gov (United States)

    Meglio, Delores

    1991-01-01

    Discussion of telecommuting possibilities focuses on a program at Information Access Company that allows indexers and abstractors to work at home. Employer and employee expectations are discussed, equipment provisions are described, employee benefits are examined, and implications for the library environment are suggested. (LRW)

  11. Environment. 1990-2001. International Atomic Energy Agency publications

    International Nuclear Information System (INIS)

    2001-05-01

    This catalog lists all sales publications of the International Atomic Energy Agency dealing with the Environment, and issued during the period 1 January 1990 - 30 April 2001. Most publications are issued in English, though some are also available in other languages. These are noted in the catalogue

  12. The Atomic Simulation Environment - A Python library for working with atoms

    DEFF Research Database (Denmark)

    Larsen, Ask Hjorth; Mortensen, Jens Jørgen; Blomqvist, Jakob

    2017-01-01

    The Atomic Simulation Environment (ASE) is a software package written in the Python programming language with the aim of setting up, steering, and analyzing atomistic simula- tions. In ASE, tasks are fully scripted in Python. The powerful syntax of Python combined with the NumPy array library make...

  13. Tune-out wavelengths for helium atom in plasma environments

    Energy Technology Data Exchange (ETDEWEB)

    Kar, Sabyasachi, E-mail: skar@hit.edu.cn, E-mail: karsabyasachi@yahoo.com; Wang, Yu-Shu; Wang, Yang [Center for Theoretical Atomic and Molecular Physics, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Jiang, Zishi [College of Physical Science and Technology, Heilongjiang University, Harbin 150080 (China)

    2016-08-15

    We investigate the effect of plasma screening on the tune-out wavelengths for helium atom using correlated exponential wave function within the framework of Debye shielding approach. The pseudostate summation technique has been used to calculate the dynamic dipole polarizability for the states (2 {sup 1}S, 3 {sup 1}S, 2 {sup 3}S, 3 {sup 3}S) of helium embedded in plasma environments. In a free-atomic system, our calculated results are in agreement with available theoretical and experimental predictions. The tune-out wavelengths show interesting behavior as functions of screening parameter.

  14. AtomPy: An Open Atomic Data Curation Environment for Astrophysical Applications

    Directory of Open Access Journals (Sweden)

    Claudio Mendoza

    2014-05-01

    Full Text Available We present a cloud-computing environment, referred to as AtomPy, based on Google-Drive Sheets and Pandas (Python Data Analysis Library DataFrames to promote community-driven curation of atomic data for astrophysical applications, a stage beyond database development. The atomic model for each ionic species is contained in a multi-sheet workbook, tabulating representative sets of energy levels, A-values and electron impact effective collision strengths from different sources. The relevant issues that AtomPy intends to address are: (i data quality by allowing open access to both data producers and users; (ii comparisons of different datasets to facilitate accuracy assessments; (iii downloading to local data structures (i.e., Pandas DataFrames for further manipulation and analysis by prospective users; and (iv data preservation by avoiding the discard of outdated sets. Data processing workflows are implemented by means of IPython Notebooks, and collaborative software developments are encouraged and managed within the GitHub social network. The facilities of AtomPy are illustrated with the critical assessment of the transition probabilities for ions in the hydrogen and helium isoelectronic sequences with atomic number Z ≤ 10.

  15. Environment, 1986-1997. International Atomic Energy Agency publications

    International Nuclear Information System (INIS)

    1998-04-01

    This catalogue lists all sales publications of the International Atomic Energy Agency dealing with Environment and issued during the period of 1986-1997. Some earlier titles which form part of an established series or are still considered of importance have been included. Most publications are in English. Proceedings of conferences, symposia and panels of experts may contain papers in languages other than English, but all of these papers have abstracts in English

  16. The Atom in a Molecule: Implications for Molecular Structure and Properties

    Science.gov (United States)

    2016-05-23

    Briefing Charts 3. DATES COVERED (From - To) 01 February 2016 – 23 May 2016 4. TITLE AND SUBTITLE The atom in a molecule: Implications for molecular...For presentation at American Physical Society - Division of Atomic , Molecular, and Optical Physics (May 2016) PA Case Number: #16075; Clearance Date...10 Energy (eV) R C--H (au) R C--H(au) The Atom in a Molecule: Implications for Molecular Structures and Properties P. W. Langhoff, Chemistry

  17. The atomic simulation environment-a Python library for working with atoms.

    Science.gov (United States)

    Hjorth Larsen, Ask; Jørgen Mortensen, Jens; Blomqvist, Jakob; Castelli, Ivano E; Christensen, Rune; Dułak, Marcin; Friis, Jesper; Groves, Michael N; Hammer, Bjørk; Hargus, Cory; Hermes, Eric D; Jennings, Paul C; Bjerre Jensen, Peter; Kermode, James; Kitchin, John R; Leonhard Kolsbjerg, Esben; Kubal, Joseph; Kaasbjerg, Kristen; Lysgaard, Steen; Bergmann Maronsson, Jón; Maxson, Tristan; Olsen, Thomas; Pastewka, Lars; Peterson, Andrew; Rostgaard, Carsten; Schiøtz, Jakob; Schütt, Ole; Strange, Mikkel; Thygesen, Kristian S; Vegge, Tejs; Vilhelmsen, Lasse; Walter, Michael; Zeng, Zhenhua; Jacobsen, Karsten W

    2017-07-12

    The atomic simulation environment (ASE) is a software package written in the Python programming language with the aim of setting up, steering, and analyzing atomistic simulations. In ASE, tasks are fully scripted in Python. The powerful syntax of Python combined with the NumPy array library make it possible to perform very complex simulation tasks. For example, a sequence of calculations may be performed with the use of a simple 'for-loop' construction. Calculations of energy, forces, stresses and other quantities are performed through interfaces to many external electronic structure codes or force fields using a uniform interface. On top of this calculator interface, ASE provides modules for performing many standard simulation tasks such as structure optimization, molecular dynamics, handling of constraints and performing nudged elastic band calculations.

  18. Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry.

    Science.gov (United States)

    Wang, Zhe-Chen; Cole, Callie A; Demarais, Nicholas J; Snow, Theodore P; Bierbaum, Veronica M

    2015-08-26

    Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications. In addition, N and O atoms are widely observed in the ISM and in the ionospheres of planets and moons. However, the chemical reactions of molecular anions with abundant interstellar and atmospheric atomic species are largely unexplored. In this paper, gas-phase reactions of deprotonated anions of benzene, pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine with N and O atoms are studied both experimentally and computationally. In all cases, the major reaction channel is associative electron detachment; these reactions are particularly important since they control the balance between negative ions and free electron densities. The reactions of the azine anions with N atoms exhibit larger rate constants than reactions of corresponding chain anions. The reactions of azine anions with O atoms are even more rapid, with complex product patterns for different reactants. The mechanisms are studied theoretically by employing density functional theory; spin conversion is found to be important in determining some product distributions. The rich gas-phase chemistry observed in this work provides a better understanding of ion-atom reactions and their contributions to ionospheric chemistry as well as the chemical processing that occurs in the boundary layers between diffuse and dense interstellar clouds.

  19. Implications of parity violation in atoms for gauge theories

    International Nuclear Information System (INIS)

    Bernabeu, J.; Jarlskog, C.

    1977-01-01

    The knowledge to be gained on neutral currents from parity-violating observables in heavy atoms is studied. After isolating the relevant couplings, the major part of the analysis is done within the framework of SU 2 xU 1 unified gauge theories of weak and electromagnetic interactions. The leptonic and hadronic sectors of these models are studied separately, by means of the available information from neutrino physics, to impose restrictions on the mass of the neutral intermediate boson and on the unification angle. The observable in atoms, which provides a link between the two sectors, is found to be powerful in discriminating among models

  20. Atomic Sulfur: An Element for Adaptation to an Oxidative Environment

    Directory of Open Access Journals (Sweden)

    Noryuki Nagahara

    2017-10-01

    Full Text Available During the period of rising oxygen concentration in the Earth’s atmosphere (Figure 1, sulfur atoms were incorporated into proteins as redox-active cysteine residues [1] and antioxidant molecules such as thioredoxin, glutathione, and glutaredoxin appeared [...

  1. Effects of the atomic environment on the electron binding energies in samarium

    Czech Academy of Sciences Publication Activity Database

    Inoyatov, A. K.; Kovalík, Alojz; Filosofov, D. V.; Ryšavý, Miloš; Vénos, Drahoslav; Yushkevich, Y. V.; Perevoshchikov, L. L.; Zhdanov, V. S.

    2016-01-01

    Roč. 207, FEB (2016), s. 38-49 ISSN 0368-2048 R&D Projects: GA ČR(CZ) GAP203/12/1896; GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : Sm-149 * atomic environment * electron ginding energy * intermediate-valence state * chemical shift * natural atomic level width Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.661, year: 2016

  2. Atom Interferometry with Ultracold Quantum Gases in a Microgravity Environment

    Science.gov (United States)

    Williams, Jason; D'Incao, Jose; Chiow, Sheng-Wey; Yu, Nan

    2015-05-01

    Precision atom interferometers (AI) in space promise exciting technical capabilities for fundamental physics research, with proposals including unprecedented tests of the weak equivalence principle, precision measurements of the fine structure and gravitational constants, and detection of gravity waves and dark energy. Consequently, multiple AI-based missions have been proposed to NASA, including a dual-atomic-species interferometer that is to be integrated into the Cold Atom Laboratory (CAL) onboard the International Space Station. In this talk, I will discuss our plans and preparation at JPL for the proposed flight experiments to use the CAL facility to study the leading-order systematics expected to corrupt future high-precision measurements of fundamental physics with AIs in microgravity. The project centers on the physics of pairwise interactions and molecular dynamics in these quantum systems as a means to overcome uncontrolled shifts associated with the gravity gradient and few-particle collisions. We will further utilize the CAL AI for proof-of-principle tests of systematic mitigation and phase-readout techniques for use in the next-generation of precision metrology experiments based on AIs in microgravity. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  3. Multiphase Modeling of Secondary Atomization in a Shock Environment

    Science.gov (United States)

    St. Clair, Jeffrey; McGrath, Thomas; Balachandar, Sivaramakrishnan

    2017-06-01

    Understanding and developing accurate modeling strategies for shock-particulate interaction remains a challenging and important topic, with application to energetic materials development, volcanic eruptions, and safety/risk assessment. This work presents computational modeling of compressible multiphase flows with shock-induced droplet atomization. Droplet size has a strong influence on the interphase momentum and heat transfer. A test case is presented that is sensitive to this, requiring the dynamic modeling of the secondary atomization process occurring when the shock impacts the droplets. An Eulerian-Eulerian computational model that treats all phases as compressible, is hyperbolic and satisfies the 2nd Law of Thermodynamics is applied. Four different breakup models are applied to the test case in which a planar shock wave encounters a cloud of water droplets. The numerical results are compared with both experimental and previously-generated modeling results. The effect of the drag relation used is also investigated. The computed results indicate the necessity of using a droplet breakup model for this application, and the relative accuracy of results obtained with the different droplet breakup and drag models is discussed.

  4. Population dynamics of excited atoms in non-Markovian environments at zero and finite temperature

    International Nuclear Information System (INIS)

    Zou Hong-Mei; Fang Mao-Fa

    2015-01-01

    The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value. (paper)

  5. Atoms

    International Nuclear Information System (INIS)

    Fuchs, Alain; Villani, Cedric; Guthleben, Denis; Leduc, Michele; Brenner, Anastasios; Pouthas, Joel; Perrin, Jean

    2014-01-01

    Completed by recent contributions on various topics (atoms and the Brownian motion, the career of Jean Perrin, the evolution of atomic physics since Jean Perrin, relationship between scientific atomism and philosophical atomism), this book is a reprint of a book published at the beginning of the twentieth century in which the author addressed the relationship between atomic theory and chemistry (molecules, atoms, the Avogadro hypothesis, molecule structures, solutes, upper limits of molecular quantities), molecular agitation (molecule velocity, molecule rotation or vibration, molecular free range), the Brownian motion and emulsions (history and general features, statistical equilibrium of emulsions), the laws of the Brownian motion (Einstein's theory, experimental control), fluctuations (the theory of Smoluchowski), light and quanta (black body, extension of quantum theory), the electricity atom, the atom genesis and destruction (transmutations, atom counting)

  6. Local atomic environment in amorphous Ge15Te85

    Science.gov (United States)

    Jóvári, P.; Kaban, I.; Hoyer, W.; Delaplane, R. G.; Wannberg, A.

    2005-03-01

    The structure of amorphous Ge15Te85 has been studied by neutron and x-ray diffraction. Experimental data have been modelled simultaneously with the reverse Monte Carlo simulation method. The contrast between structure factors together with the application of some plausible physical constraints allowed the separation of the three partial pair correlation functions and determination of Ge and Te local environment.

  7. Implications of changing land uses on physical environment in ...

    African Journals Online (AJOL)

    The aim of this study was to assess the attendant problems as well as implications of changing land uses on physical environment in Calabar Municipality, the capital city of Cross River State in Nigeria. The study adopted the systematic random sampling technique in the administration of questionnaires. The sample size for ...

  8. Origin of the smaller conductances of Rh, Pb, and Co atomic junctions in hydrogen environment

    Science.gov (United States)

    Li, Xue; Chen, Mingyan; Ye, Xiang; Xie, Yi-qun; Ke, San-huang

    2015-02-01

    We study theoretically the structural and electronic origins of the smaller conductances (one conductance quantum, G0, and smaller) of Rh, Pb, and Co metal atomic junctions (MAJs) in a hydrogen environment, as were measured in recent experiments. For the Rh MAJs, the 1G0 conductance is attributed to a stable contact bridged by a single hydrogen molecule whose antibonding state provides a single transport channel. For the Pb and Co MAJs the 1G0 conductance is, however, ascribed to a linear atomic chain adsorbing two dissociated H atoms, which largely reduces the density of states at the Fermi energy with respect to the pure ones. On the other hand, the small conductances of 0.3G0 (Rh) and 0.2G0 (Co) are due to H-decorated atomic chains connected to electrodes by a H atom.

  9. Origin of the smaller conductances of Rh, Pb, and Co atomic junctions in hydrogen environment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xue; Chen, Mingyan; Ye, Xiang; Xie, Yi-qun, E-mail: yqxie@shnu.edu.cn [Department of Physics, Shanghai Normal University, 100 Guilin Road, Shanghai 200232 (China); Ke, San-huang, E-mail: shke@tongji.edu.cn [MOE Key Laboratory of Advanced Microstructured Materials, School of Physics Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2015-02-14

    We study theoretically the structural and electronic origins of the smaller conductances (one conductance quantum, G{sub 0}, and smaller) of Rh, Pb, and Co metal atomic junctions (MAJs) in a hydrogen environment, as were measured in recent experiments. For the Rh MAJs, the 1G{sub 0} conductance is attributed to a stable contact bridged by a single hydrogen molecule whose antibonding state provides a single transport channel. For the Pb and Co MAJs the 1G{sub 0} conductance is, however, ascribed to a linear atomic chain adsorbing two dissociated H atoms, which largely reduces the density of states at the Fermi energy with respect to the pure ones. On the other hand, the small conductances of 0.3G{sub 0} (Rh) and 0.2G{sub 0} (Co) are due to H-decorated atomic chains connected to electrodes by a H atom.

  10. Resonance interaction energy between two entangled atoms in a photonic bandgap environment.

    Science.gov (United States)

    Notararigo, Valentina; Passante, Roberto; Rizzuto, Lucia

    2018-03-26

    We consider the resonance interaction energy between two identical entangled atoms, where one is in the excited state and the other in the ground state. They interact with the quantum electromagnetic field in the vacuum state and are placed in a photonic-bandgap environment with a dispersion relation quadratic near the gap edge and linear for low frequencies, while the atomic transition frequency is assumed to be inside the photonic gap and near its lower edge. This problem is strictly related to the coherent resonant energy transfer between atoms in external environments. The analysis involves both an isotropic three-dimensional model and the one-dimensional case. The resonance interaction asymptotically decays faster with distance compared to the free-space case, specifically as 1/r 2 compared to the 1/r free-space dependence in the three-dimensional case, and as 1/r compared to the oscillatory dependence in free space for the one-dimensional case. Nonetheless, the interaction energy remains significant and much stronger than dispersion interactions between atoms. On the other hand, spontaneous emission is strongly suppressed by the environment and the correlated state is thus preserved by the spontaneous-decay decoherence effects. We conclude that our configuration is suitable for observing the elusive quantum resonance interaction between entangled atoms.

  11. Noncontact atomic force microscopy in liquid environment with quartz tuning fork and carbon nanotube probe

    DEFF Research Database (Denmark)

    Kageshima, M.; Jensenius, Henriette; Dienwiebel, M.

    2002-01-01

    A force sensor for noncontact atomic force microscopy in liquid environment was developed by combining a multiwalled carbon nanotube (MWNT) probe with a quartz tuning fork. Solvation shells of octamethylcyclotetrasiloxane surface were detected both in the frequency shift and dissipation. Due...

  12. Construction of high-dimensional neural network potentials using environment-dependent atom pairs.

    Science.gov (United States)

    Jose, K V Jovan; Artrith, Nongnuch; Behler, Jörg

    2012-05-21

    An accurate determination of the potential energy is the crucial step in computer simulations of chemical processes, but using electronic structure methods on-the-fly in molecular dynamics (MD) is computationally too demanding for many systems. Constructing more efficient interatomic potentials becomes intricate with increasing dimensionality of the potential-energy surface (PES), and for numerous systems the accuracy that can be achieved is still not satisfying and far from the reliability of first-principles calculations. Feed-forward neural networks (NNs) have a very flexible functional form, and in recent years they have been shown to be an accurate tool to construct efficient PESs. High-dimensional NN potentials based on environment-dependent atomic energy contributions have been presented for a number of materials. Still, these potentials may be improved by a more detailed structural description, e.g., in form of atom pairs, which directly reflect the atomic interactions and take the chemical environment into account. We present an implementation of an NN method based on atom pairs, and its accuracy and performance are compared to the atom-based NN approach using two very different systems, the methanol molecule and metallic copper. We find that both types of NN potentials provide an excellent description of both PESs, with the pair-based method yielding a slightly higher accuracy making it a competitive alternative for addressing complex systems in MD simulations.

  13. The relationship between the life environment of the atomic bomb survivors (Hibakusha) and their cardiovascular disorders

    International Nuclear Information System (INIS)

    Tasaka, Masatoshi; Saito, Osamu; Miyaki, Sumiyo; Watabu, Akiko

    1978-01-01

    In order to observe clinically the effects of the atomic bomb on the human body (and on the environment), subjects were divided into group A (persons living in Hiroshima city more than 10 years after dropping of the atomic bomb) and group B (persons who changed their residence within 1 month). Group A was divided into two separate groups: group A 1 (persons living in segregated areas), and group A 2 (persons living in other areas). General examinations showed no abnormal findings. Incidence of abnormal ECG findings was higher in subjects living in segregated areas and was also higher in women than in men. (Namekawa, K.)

  14. Two-dimensional atomic hydrogen concentration maps in hot-filament diamond-deposition environment

    Science.gov (United States)

    Larjo, J.; Koivikko, H.; Lahtonen, K.; Hernberg, R.

    This paper reports the two-dimensional mapping of atomic hydrogen concentration with two-photon excited laser induced fluorescence in a multi-wire grid hot-filament chemical vapor deposition reactor. The measurements were made in a diamond film deposition environment under different filament temperatures and wire configurations. The measurement was calibrated with a titration reaction using NO2 as a titrant. The kinetic gas temperature in the reactor was measured from the Doppler broadening of the Lyman-β transition excited in the fluorescence. The filament temperature was found to have a significant effect on atomic hydrogen production and transfer to the substrate. The axial concentration distributions were compared to a one-dimensional kinetic gas-surface chemistry model with good agreement. The model produced a reasonable estimate for the bulk diamond film growth rate.

  15. Chemical environment of iron atoms in iron oxynitride films synthesized by reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Grafoute, M.; Petitjean, C.; Rousselot, C.; Pierson, J.F.; Greneche, J.M.

    2007-01-01

    An iron oxynitride film was deposited on silicon and glass substrates by magnetron sputtering in an Ar-N 2 -O 2 reactive mixture. Rutherford back-scattering spectrometry was used to determine the film composition (Fe 1.06 O 0.35 N 0.65 ). X-ray diffraction revealed the formation of a face-centred cubic (fcc) structure with a lattice parameter close to that of γ'''-FeN. X-ray photoelectron spectroscopy showed the occurrence of Fe-N and Fe-O bonds in the film. The local environment of iron atoms studied by 57 Fe Moessbauer spectrometry at both 300 and 77 K gives clear evidence that the Fe 1.06 O 0.35 N 0.65 is not a mixture of iron oxide and iron nitride phases. Despite a small amount of an iron nitride phase, the main sample consists of an iron oxynitride phase with an NaCl-type structure where oxygen atoms partially substitute for nitrogen atoms, thus indicating the formation of a iron oxynitride with an fcc structure

  16. Impact of operation of Narora Atomic Power Station in the environment

    International Nuclear Information System (INIS)

    Kumar, Avinash; Gautam, Y.P.; Kumar, D.; Sharma, S.; Rao, K.S.; Kumar, V.; Kumar, J.; Singh, B.; Sharma, A.K.; Ravi, P.M.

    2012-01-01

    The Narora Atomic Power Station (NAPS) has twin units of Pressurised Heavy Water Reactor (PHWR) with electrical generating capacity of 220 MWe each. Unit I attained critical in March 1989 and Unit II in October 1991. Commercial operation commenced with effect from 01.01.91 and 30.06.92 for Unit I and Unit II respectively. The area of the plant site is fairly flat terrain, gently sloping towards LGC and PLGC. The site lies in Indo-Gangetic alluvium, bordered on the north by the Shivalic foothills. The land around the site is predominantly agricultural. The main crop is wheat followed by other cereals. There are guava and mango groves and vegetable farms around the site. Major contribution of radioactive pollution to the environment is through liquid waste and gaseous emission as per the technical specifications. The important radionuclides in the liquid effluents are 3 H, 90 Sr, 131 I, 137 Cs etc. The liquid effluents are discharged to canal after proper dilution. Reactor off-gases consist mostly of Fission Product Noble Gases (FPNGs), 41 Ar and H. The effluents from the off-gas system are led through a high efficiency filter system and discharged to atmosphere through a 145 m stack. These radionuclides may reach to the environment through possible pathways. Health Physics Division, Bhabha Atomic Research Centre has set up a well equipped Environmental Survey Laboratory (ESL) at NAPS before the commissioning of plant

  17. The hydrogen-atom environment of the ether oxygen atom in crystal structures of some representative muscarinic agonists

    Science.gov (United States)

    Kroon, J.; Scherrenberg, R. L.; Kooijman, H.; Kanters, J. A.

    1990-06-01

    The hypothesis that the ether oxygen atom in muscarinic agonists acts as a hydrogen-bond acceptor is supported by evidence from crystallographic data. The same evidence suggests that in such interactions N +CH⋯O bonds donated by the ligand to the receptor may be involved.

  18. Tip Effect of the Tapping Mode of Atomic Force Microscope in Viscous Fluid Environments.

    Science.gov (United States)

    Shih, Hua-Ju; Shih, Po-Jen

    2015-07-28

    Atomic force microscope with applicable types of operation in a liquid environment is widely used to scan the contours of biological specimens. The contact mode of operation allows a tip to touch a specimen directly but sometimes it damages the specimen; thus, a tapping mode of operation may replace the contact mode. The tapping mode triggers the cantilever of the microscope approximately at resonance frequencies, and so the tip periodically knocks the specimen. It is well known that the cantilever induces extra liquid pressure that leads to drift in the resonance frequency. Studies have noted that the heights of protein surfaces measured via the tapping mode of an atomic force microscope are ~25% smaller than those measured by other methods. This discrepancy may be attributable to the induced superficial hydrodynamic pressure, which is worth investigating. In this paper, we introduce a semi-analytical method to analyze the pressure distribution of various tip geometries. According to our analysis, the maximum hydrodynamic pressure on the specimen caused by a cone-shaped tip is ~0.5 Pa, which can, for example, pre-deform a cell by several nanometers in compression before the tip taps it. Moreover, the pressure calculated on the surface of the specimen is 20 times larger than the pressure without considering the tip effect; these results have not been motioned in other papers. Dominating factors, such as surface heights of protein surface, mechanical stiffness of protein increasing with loading velocity, and radius of tip affecting the local pressure of specimen, are also addressed in this study.

  19. Integrating nature and nurture : Implications of person-environment correlations and interactions for developmental psychopathology

    NARCIS (Netherlands)

    Rutter, M; Dunn, J; Plomin, R; Simonoff, E; Pickles, A; Maughan, B; Ormel, J; Meyer, J; Eaves, L

    1997-01-01

    The developmental interplay between nature and nurture is discussed, with particular reference to implications for research in developmental psychopathology. The general principles include individual differences in reactivity to the environment, two-way interplay between intraindividual biology and

  20. Financial implications for built environment consultants working at ...

    African Journals Online (AJOL)

    Adendorff et al • Financial implications. 133 that should be avoided. One of the pitfalls is pricing – if the pricing is wrong for a particular project, either the consultant or the client may thus be prejudiced (Moss, 2000: 1). Working at risk should however not be confused with a simple deferral of the consultant's fee (or a portion ...

  1. Climate Change Implications to the Global Security Environment, U.S. Interests, and Future Naval Operations

    Science.gov (United States)

    2011-03-14

    Title: Climate Change Implications to the Global Security Environment , U.S. Interests, and Future Naval Operations Thesis: This paper aims to...United States over the next 20 years. ·This is because it will aggravate existing problems such as poverty tensions, environmental degradation...Implications on the Global Security Environment As discussed above, the physical effects of climate change -rising sea levels, rising temperatures

  2. The Natural and Human Environments in Nigeria: Their Implications ...

    African Journals Online (AJOL)

    difficult. The paper separates these factors into natural and artificial components and relates them to the sociocultural environments prevalent in Nigeria. This paper elaborates on the various features, which designers often ignore, and recommends a simultaneous interaction between architecture and the environment.

  3. Generation of long-living entanglement between two distant three-level atoms in non-Markovian environments.

    Science.gov (United States)

    Li, Chuang; Yang, Sen; Song, Jie; Xia, Yan; Ding, Weiqiang

    2017-05-15

    In this paper, a scheme for the generation of long-living entanglement between two distant Λ-type three-level atoms separately trapped in two dissipative cavities is proposed. In this scheme, two dissipative cavities are coupled to their own non-Markovian environments and two three-level atoms are driven by the classical fields. The entangled state between the two atoms is produced by performing Bell state measurement (BSM) on photons leaving the dissipative cavities. Using the time-dependent Schördinger equation, we obtain the analytical results for the evolution of the entanglement. It is revealed that, by manipulating the detunings of classical field, the long-living stationary entanglement between two atoms can be generated in the presence of dissipation.

  4. Dependence of Vibronic Coupling on Molecular Geometry and Environment: Bridging Hydrogen Atom Transfer and Electron–Proton Transfer

    Science.gov (United States)

    2016-01-01

    The rate constants for typical concerted proton-coupled electron transfer (PCET) reactions depend on the vibronic coupling between the diabatic reactant and product states. The form of the vibronic coupling is different for electronically adiabatic and nonadiabatic reactions, which are associated with hydrogen atom transfer (HAT) and electron–proton transfer (EPT) mechanisms, respectively. Most PCET rate constant expressions rely on the Condon approximation, which assumes that the vibronic coupling is independent of the nuclear coordinates of the solute and the solvent or protein. Herein we test the Condon approximation for PCET vibronic couplings. The dependence of the vibronic coupling on molecular geometry is investigated for an open and a stacked transition state geometry of the phenoxyl-phenol self-exchange reaction. The calculations indicate that the open geometry is electronically nonadiabatic, corresponding to an EPT mechanism that involves significant electronic charge redistribution, while the stacked geometry is predominantly electronically adiabatic, corresponding primarily to an HAT mechanism. Consequently, a single molecular system can exhibit both HAT and EPT character. The dependence of the vibronic coupling on the solvent or protein configuration is examined for the soybean lipoxygenase enzyme. The calculations indicate that this PCET reaction is electronically nonadiabatic with a vibronic coupling that does not depend significantly on the protein environment. Thus, the Condon approximation is shown to be valid for the solvent and protein nuclear coordinates but invalid for the solute nuclear coordinates in certain PCET systems. These results have significant implications for the calculation of rate constants, as well as mechanistic interpretations, of PCET reactions. PMID:26412613

  5. Influence of the atomic industry branches' on the Kazakhstan environment status

    International Nuclear Information System (INIS)

    Ibraev, R.; Tugel'baev, S.S.

    2001-01-01

    In the paper an the atomic industry branches' influence on the Kazakhstan environment status is considered. It is noted that Kazakhstan in only country in the world where nuclear strategic programs (USSR and CIS) were carried out without control, any limits, wide-scaly and in a full cycle. This is mine, reprocessing of strategic ores, preparation (partial), testing and use of nuclear and thermonuclear warheads in both military and peaceful aims, radioactive wastes disposal. Due to non-observance by industry branches of the principal normative requirements of radiation safety (were in existence and present ones) in the republic there is not territorial delimitation of the special objects with control area that caused negative influence of these objected were exposed vast regions both out-side and inter-sites area. So Kazakhstan nature scale-wide contamination is the existing reality. It is stressed, that mining and reprocessing uranium enterprises have negative contribution in the bio-geo-media. In this case it is especially hazard the underground sulfuric leaching technology is applying in the uranium mine industry. The technology is much cheaper but it ecologically in dozen times danger in comparison with applied in other countries the carbonate leaching method

  6. Reaction and Protection of Electrical Wire Insulators in Atomic-oxygen Environments

    Science.gov (United States)

    Hung, Ching-Cheh; Cantrell, Gidget

    1994-01-01

    Atomic-oxygen erosion on spacecraft in low Earth orbit is an issue which is becoming increasingly important because of the growing number of spacecraft that will fly in the orbits which have high concentrations of atomic oxygen. In this investigation, the atomic-oxygen durability of three types of electrical wire insulation (carbon-based, fluoropolymer, and polysiloxane elastomer) were evaluated. These insulation materials were exposed to thermal-energy atomic oxygen, which was obtained by RF excitation of air at a pressure of 11-20 Pa. The effects of atomic-oxygen exposure on insulation materials indicate that all carbon-based materials erode at about the same rate as polyamide Kapton and, therefore, are not atomic-oxygen durable. However, the durability of fluoropolymers needs to be evaluated on a case by case basis because the erosion rates of fluoropolymers vary widely. For example, experimental data suggest the formation of atomic fluorine during atomic-oxygen amorphous-fluorocarbon reactions. Dimethyl polysiloxanes (silicone) do not lose mass during atomic-oxygen exposure, but develop silica surfaces which are under tension and frequently crack as a result of loss of methyl groups. However, if the silicone sample surfaces were properly pretreated to provide a certain roughness, atomic oxygen exposure resulted in a sturdy, non-cracked atomic-oxygen durable SiO2 layer. Since the surface does not crack during such silicone-atomic oxygen reaction, the crack-induced contamination by silicone can be reduced or completely stopped. Therefore, with proper pretreatment, silicone can be either a wire insulation material or a coating on wire insulation materials to provide atomic-oxygen durability.

  7. Genotype–environment interactions and their translational implications

    OpenAIRE

    Baye, Tesfaye M; Abebe, Tilahun; Wilke, Russell A

    2011-01-01

    Organisms frequently encounter different environmental conditions. The physiological and behavioral responses to these conditions depend on the genetic make up of individuals. Genotype generally remains constant from one environment to another, although occasional spontaneous mutations may occur which cause it to change. However, when the same genotype is subjected to different environments, it can produce a wide range of phenotypes. These phenotypic variations are attributable to the effect ...

  8. Guattari's Philosophy of Environment and its Implications for ...

    African Journals Online (AJOL)

    In this essay I introduce Guattari's philosophy of environment and focus in particular on his ecosophy which comprises three interlocking dimensions of self, society and nature. Guattari argues that integrated world capitalism is concerned more than anything else with the production of human subjectivity. He suggests that ...

  9. Reaction of gaseous mercury with molecular iodine, atomic iodine, and iodine oxide radicals - Kinetics, product studies, and atmospheric implications

    Science.gov (United States)

    Raofie, F.; Snider, G.; Ariya, P.

    2008-12-01

    Mercury is present in the Earth's atmosphere mainly in elemental form. The chemical transformation of mercury in the atmosphere may influence its bioaccumulation in the human food chain as well as its global cycling. We carried out the first kinetic and product studies of the reactions of gaseous mercury with molecular iodine, atomic iodine, and iodine oxide radicals at tropospheric pressure (similar to 740 Torr) and 296 ± 2 K in air and in N2 (1 Torr = 133.3 Pa). Atomic iodine was formed using UV photolysis of CH2I2. IO radicals were formed by the UV photolysis of CH2I2 in the presence of ozone The reaction kinetics were studied using absolute rate techniques with gas chromatographic and mass spectroscopic detection (GC-MS). The measured rate coefficient for the reaction of Hg{0} with I2 was vapor atomic fluorescence spectrometer (CVAFS), and a high-resolution transmission electron microscope (HRTEM) coupled to an energy dispersive spectrometer (EDS). The major reaction products identified were HgI2, HgO, and HgIO or HgOI. The implications of the results are discussed with regards to both the chemistry of atmospheric mercury and its potential implications in the biogeochemical cycling of mercury.

  10. Gene x environment interactions as dynamical systems: clinical implications

    Directory of Open Access Journals (Sweden)

    Sarah S. Knox

    2015-12-01

    Full Text Available The etiology and progression of the chronic diseases that account for the highest rates of mortality in the US, namely, cardiovascular diseases and cancers, involve complex gene x environment interactions. Yet despite the general agreement in the medical community given to this concept, there is a widespread lack of clarity as to what the term ‘interaction’ actually means. The consequence is the use of linear statistical methods to describe processes that are biologically nonlinear, resulting in clinical applications that are often not optimal. Gene x environment interactions are characterized by dynamic, nonlinear molecular networks that change and evolve over time; and by emergent properties that cannot be deduced from the characteristics of their individual subcomponents. Given the nature of these systemic properties, reductionist methods are insufficient for fully providing the information relevant to improving therapeutic outcomes. The purpose of this article is to provide an overview of these concepts and their relevance to prevention and interventions.

  11. Future Environments for Europe: Some Implications of Alternative Development Paths

    OpenAIRE

    Stigliani, W.M.; Brouwer, F.; Munn, R.E.; Shaw, R.W.; Antonovsky, M.Y.

    1989-01-01

    With the completion of the Report of the World Commission on Environment and Development (popularly known also as the Brundtland Commission Report) in 1987, and the subsequent worldwide attention given to that study, the concept of "ecologically sustainable development" has gained broad recognition. It is now commonly acknowledged that economic development and ecological sustainability are not contradictory goals. To the contrary, they are interdependent -- the economy of a country cannot gro...

  12. The petroleum refining industry and the implications for the environment

    International Nuclear Information System (INIS)

    Saraiva, Gerardo Jose de Pontes

    2000-01-01

    The petroleum refining industry is basically concerned with the production of oil, lubricants and intermediate petrochemical products, utilizing crude oil as its main raw material. Petroleum refining, a distillation process that breaks hydrocarbons into fractions, eliminating undesired impurities, generates irreducible residues. Until the industrial revolution, the residues were essentially organic, susceptible to the attack of agents of destruction and transformation (bacterium, fungi, etc). Suddenly, due to the intensification of human activities of modern man, nature scattered across the planet more resistant products, many of them with long life times, that produce a deeper impact in the environment. Almost entirely marine is the pollution that results from increasing quantity of hydrocarbons dumped into the sea, a problem that is aggravated by the development of manufacturing and transportation of petroleum products. The expansion of the petroleum commerce, using essentially maritime transportation, has increased considerably the probability of accidents increasing the risks of environment pollution. This work presents suggestions and possible solutions to minimize the problem of environment pollution, caused by refining and transportation of this combustible, essential to present time industry. (author)

  13. Particles in the oceans: Implication for a safe marine environment.

    Science.gov (United States)

    Blasco, Julian; Corsi, Ilaria; Matranga, Valeria

    2015-10-01

    Strategies and technologies for the ecosafety assessment and design of engineered particles entering the marine environment are urgently needed. As the application of nanoparticles in science and technology grows, the need to understand their impact on the marine environment becomes increasingly important. This Editorial introduces a Special Issue on the topic of a sustainable and safety use of nanoparticles for protecting, recovering and supporting the oceans' environment and consequently human health. The issue focus on the impact of micro/nano-plastics and metallic nanoparticles on marine organisms, as well as some methodological aspects associated to the eco/toxicity and analytical approaches for in deep physico-chemical characterization of nanoparticles in marine waters and sediment media. Important and urgent topics are addressed in the field of nano-ecosafety in order to assess more precisely both exposure routes and environmental hazards of nanoparticles in the ocean. Ecotoxicological and toxicological data, obtained using a wide variety of organisms representative of different trophic levels and biological organization, from whole animals to macromolecules, will be useful for a better definition of cleaner and safer nanoparticles. Efforts in developing a broad understanding of target species, expected results, benchmarks and timelines, will be of primary importance. Copyright © 2015. Published by Elsevier Ltd.

  14. Microplastics in aquatic environments: Implications for Canadian ecosystems.

    Science.gov (United States)

    Anderson, Julie C; Park, Bradley J; Palace, Vince P

    2016-11-01

    Microplastics have been increasingly detected and quantified in marine and freshwater environments, and there are growing concerns about potential effects in biota. A literature review was conducted to summarize the current state of knowledge of microplastics in Canadian aquatic environments; specifically, the sources, environmental fate, behaviour, abundance, and toxicological effects in aquatic organisms. While we found that research and publications on these topics have increased dramatically since 2010, relatively few studies have assessed the presence, fate, and effects of microplastics in Canadian water bodies. We suggest that efforts to determine aquatic receptors at greatest risk of detrimental effects due to microplastic exposure, and their associated contaminants, are particularly warranted. There is also a need to address the gaps identified, with a particular focus on the species and conditions found in Canadian aquatic systems. These gaps include characterization of the presence of microplastics in Canadian freshwater ecosystems, identifying key sources of microplastics to these systems, and evaluating the presence of microplastics in Arctic waters and biota. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  15. Fundamental Interactions for Atom Interferometry with Ultracold Quantum Gases in a Microgravity Environment

    Science.gov (United States)

    D'Incao, Jose P.; Willians, Jason R.

    2015-05-01

    Precision atom interferometers (AI) in space are a key element for several applications of interest to NASA. Our proposal for participating in the Cold Atom Laboratory (CAL) onboard the International Space Station is dedicated to mitigating the leading-order systematics expected to corrupt future high-precision AI-based measurements of fundamental physics in microgravity. One important focus of our proposal is to enhance initial state preparation for dual-species AIs. Our proposed filtering scheme uses Feshbach molecular states to create highly correlated mixtures of heteronuclear atomic gases in both their position and momentum distributions. We will detail our filtering scheme along with the main factors that determine its efficiency. We also show that the atomic and molecular heating and loss rates can be mitigated at the unique temperature and density regimes accessible on CAL. This research is supported by the National Aeronautics and Space Administration.

  16. Phytochrome-mediated responses: Implications for controlled environment research facilities

    Science.gov (United States)

    Smith, Harry

    1994-01-01

    Light is undoubtedly the most important environmental variable for plant growth and development; plants not only use radiant energy in photosynthesis, they also respond to the quantity, quality, direction and timing of incident radiation through photomorphogenic response that can have huge effects on the rate of growth and the pattern of development. It is surprising, therefore, that the manufacturers and suppliers of controlled environment facilities have been singularly uninventive in the design of the lighting assemblies they provide. The consumer has one choice only - a lighting assembly that provides irradiance levels usually only a fraction of sunlight, and a control system that is limited to regulating the timing of the on-off switch. The reasons for these limitations are partly technological, but in the main they result from ignorance on the part of both the consumer and the manufacturer. A specific and powerful example of this ignorance relates to the importance of the so-called far-red wavelengths (FR = 700-800 nm). Because the human eye can hardly detect wavelengths above 700 nm, and photosynthesis also cuts off at about 700 nm, the majority of plant and crop physiologists are still almost completely unaware that FR radiation can have massive effects on growth rate and development. In consequence, most growth cabinets have light sources based on fluorescent tubes, and provide very little FR apart from that emitted by a token number of small incandescent bulbs. Larger growth facilities often use broader spectrum light sources, but growth facilities that provide the capability to vary the FR incident upon the plants are about as abundant as seals in the Sahara. This article sets the background of the significance of FR radiation in the natural environment and its importance for plant growth and development in the hope that it might inform intelligently those concerned with improving the design of plant growth facilities.

  17. Phytochrome-mediated responses implications for controlled environment research facilities

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H. [Univ. of Leicester (United Kingdom)

    1994-12-31

    Light is undoubtedly the most important environmental variable for plant growth and development; plants not only use radiant energy in photosynthesis, they also respond to the quantity, quality, direction and timing of incident radiation through photomorphogenic responses that can have huge effects on the rate of growth and the pattern of development. It is surprising, therefore, that the manufacturers and suppliers of controlled environment facilities have been singularly uninventive in the design of the lighting assemblies they provide. The consumer has one choice only - a lighting assembly that provides irradiance levels usually only a fraction of sunlight, and a control system that is limited to regulating the timing of the on-off switch. The reasons for these limitations are partly technological, but in the main they result from ignorance on the part of both the consumer and the manufacturer. A specific and powerful example of this ignorance relates to the importance of the so-called far-red wavelengths (FR = 700-800 nm). Because the human eye can hardly detect wavelengths above 700 nm, and photosynthesis also cuts off at ca. 700 mn, the majority of plant and crop physiologists are still almost completely unaware that FR radiation can have massive effects on growth rate and development. In consequence, most growth cabinets have light sources based on fluorescent tubes, and provide very little FR apart from that emitted by a token number of small incandescent bulbs. Larger growth facilities often use broader spectrum light sources, but growth facilities that provide the capability to vary the FR incident upon the plants are about as abundant as seals in the Sahara. This article sets the background of the significance of FR radiation in the natural environment and its importance for plant growth and development in the hope that it might inform intelligently those concerned with improving the design of plant growth facilities.

  18. Mass Wasting In Planetary Environments: Implications For Seismicity

    Science.gov (United States)

    Weber, R. C.; Nahm, A. L.; Schmerr, N.

    2015-01-01

    On Earth, mass wasting events such as rock falls and landslides are well known conse-quences of seismic activity. Through a variety of re-mote sensing techniques, tectonic faults have been pos-itively identified on all four of the inner planets, Earth's Moon, several outer planet satellites, and aster-oids. High-resolution imaging has furthermore ena-bled positive identification of mass wasting events on many of these bodies. On Mars, it has been suggested that fallen boulders may be indicative of pale-omarsquakes. On the Moon, meteor impacts and moonquakes have likewise been suggested as potential triggering mechanisms for mass wasting. Indeed, we know from the Apollo era that the Moon experienc-es a wide variety of seismicity. Seismicity estimates play an important role in creat-ing regional geological characterizations, which are useful not only for understanding a planet's formation and evolution, but also of key importance to site selec-tion for landed missions. Here we investigate the re-gional effects of seismicity in planetary environments with the goal of determining whether surface features such as landslides and boulder trails on the Moon, Mars, and Mercury could be triggered by fault motion. We attempt to quantify the amount of near-source ground shaking necessary to mobilize the mate-rial observed in various instances of mass wasting.

  19. Rydberg atom state mixing in a time-dependent electric field and implications for selective-field ionization

    International Nuclear Information System (INIS)

    Symons, T.R.; Cornett, S.T.; Cavagnero, M.J.; Harmin, D.A.

    1996-01-01

    The mixing and ionization of states of a Rydberg atom subject to a time-dependent electric field is studied by direct integration of the Schoredinger equation. A linearly ramped electric field is used, F(t) = Ft, with ionization modeled by field-dependent widths Γ(F). In the linear Stark regime, hydrogenic levels are coupled by F(t) through the atomic core, parameterized by quantum defects. Amplitudes are evaluated in spherical and parabolic hydrogenic bases, and in the nonhydrogenic adiabatic basis. The integration is performed using a modified divided difference form of the Adam Pece formulas; local extrapolation is also used to increase accuracy. The mixing of the levels is first studied for a single manifold and compared to earlier work. Then the multiple-manifold case is studied for Na atoms initially populated in n ∼ 25. Probability distributions for the time-evolved states are produced in the different bases, as well as 3-dimensional movies of the evolving and ionizing wave function. Implications for analysis of selective-field ionization signals are discussed

  20. Actinide discharges from Sellafield - a summary of behaviour in the environment and the radiological implications

    International Nuclear Information System (INIS)

    Coughtrey, P.J.; Jackson, D.; Martin, A.; Thorne, M.C.

    1985-05-01

    This report provides a summary of: information on the quantities of actinides discharged from Sellafield, their distribution in the environment and the radiological implications; potential long-term trends and exposure pathways that may require investigation; and research in progress and requirements for further research. (author)

  1. Empowering youth sport environments: Implications for daily moderate-to-vigorous physical activity and adiposity

    Directory of Open Access Journals (Sweden)

    Sally A.M. Fenton

    2017-12-01

    Conclusion: Fostering more empowering youth sport environments may hold implications for the prevention of excess adiposity, through encouraging higher habitual MVPA engagement. Findings may inform the optimal design of youth sport settings for MVPA promotion, and contribute towards associated healthy weight maintenance amongst youth active in this context. Longitudinal and intervention studies are required to confirm these results.

  2. Plasma out of thermodynamical equilibrium: influence of the plasma environment on atomic structure and collisional cross sections

    International Nuclear Information System (INIS)

    Belkhiri, Madeny

    2014-01-01

    In hot dense plasmas, the free-electron and ion spatial distribution may strongly affect the atomic structure. To account for such effects we have implemented a potential correction based on the uniform electron gas model and on a Thomas-Fermi Approach in the Flexible Atomic Code (FAC). This code has been applied to obtain energies, wave-functions and radiative rates modified by the plasma environment. In hydrogen-like ions, these numerical results have been successfully compared to an analytical calculation based on first-order perturbation theory. In the case of multi-electron ions, we observe level crossings in agreement with another recent model calculation. Various methods for the collision cross-section calculations are reviewed. The influence of plasma environment on these cross-sections is analyzed in detail. Some analytical expressions are proposed for hydrogen-like ions in the limit where Born or Lotz approximations apply and are compared to the numerical results from the FAC code. Finally, from this work, we study the influence of the plasma environment on our collisional-radiative model so-called Foch. Because of this environment, the mean charge state of the ions increases. The line shift is observed on the bound-bound emission spectra. A good agreement is found between our work and experimental data on a Titanium plasma. (author) [fr

  3. Stability investigation of a high number density Pt1/Fe2O3single-atom catalyst under different gas environments by HAADF-STEM.

    Science.gov (United States)

    Duan, Sibin; Wang, Rongming; Liu, Jingyue

    2018-05-18

    Catalysis by supported single metal atoms has demonstrated tremendous potential for practical applications due to their unique catalytic properties. Unless they are strongly anchored to the support surfaces, supported single atoms, however, are thermodynamically unstable, which poses a major obstacle for broad applications of single-atom catalysts (SACs). In order to develop strategies to improve the stability of SACs, we need to understand the intrinsic nature of the sintering processes of supported single metal atoms, especially under various gas environments that are relevant to important catalytic reactions. We report on the synthesis of high number density Pt 1 /Fe 2 O 3 SACs using a facial strong adsorption method and the study of the mobility of these supported Pt single atoms at 250 °C under various gas environments that are relevant to CO oxidation, water-gas shift, and hydrogenation reactions. Under the oxidative gas environment, Fe 2 O 3 supported Pt single atoms are stable even at high temperatures. The presence of either CO or H 2 molecules in the gas environment, however, facilitates the movement of the Pt atoms. The strong interaction between CO and Pt weakens the binding between the Pt atoms and the support, facilitating the movement of the Pt single atoms. The dissociation of H 2 molecules on the Pt atoms and their subsequent interaction with the oxygen species of the support surfaces dislodge the surface oxygen anchored Pt atoms, resulting in the formation of Pt clusters. The addition of H 2 O molecules to the CO or H 2 significantly accelerates the sintering of the Fe 2 O 3 supported Pt single atoms. An anchoring-site determined sintering mechanism is further proposed, which is related to the metal-support interaction.

  4. Evaluation of the Physiological Challenges in Extreme Environments: Implications for Enhanced Training, Operational Performance and Sex-Specific Responses

    Science.gov (United States)

    2017-10-01

    Evaluation of the physiological challenges in extreme environments: Implications for enhanced training, operational performance and sex-specific... evaluated . Furthermore, actual performance based measures must be evaluated after a period of training/acclimation. The aim of this project is...AWARD NUMBER: W81XWH-15-2-0075 TITLE: Evaluation of the Physiological Challenges in Extreme Environments: Implications for Enhanced Training

  5. Neutral atomic absorption lines and far-UV extinction: Possible implications for depletions and grain parameters

    Science.gov (United States)

    Welty, Daniel E.

    1990-01-01

    Researchers examine nine lines of sight within the Galaxy and one in the Large Magellanic Cloud (LMC) for which data on both neutral atomic absorption lines (Snow 1984; White 1986; Welty, Hobbs, and York 1989) and far UV extinction (Bless and Savage 1972; Jenkins, Savage, and Spitzer 1986) are available, in order to test the assumption that variations in gamma/alpha will cancel in taking ratios of the ionization balance equation, and to try to determine to what extent that assumption has affected the aforementioned studies of depletions and grain properties.

  6. Technologies for protection of the Space Station power system surfaces in atomic oxygen environment

    Science.gov (United States)

    Nahra, Henry K.; Rutledge, Sharon K.

    1988-01-01

    Technologies for protecting Space Station surfaces from degradation caused by atomic oxygen are discussed, stressing protection of the power system surfaces. The Space Station power system is described and research concerning the solar array surfaces and radiator surfaces is examined. The possibility of coating the solar array sufaces with a sputter deposited thin film of silicon oxide containing small concentrations of polytetrafluoroethylene is presented. Hexamethyldisiloxane coating for these surfaces is also considered. For the radiator surfaces, possible coatings include silver teflon thermal coating and zinc orthotitanate.

  7. Atomic force microscopy based nanoindentation study of onion abaxial epidermis walls in aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Xiaoning; Tittmann, Bernhard [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Kim, Seong H. [Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-01-14

    An atomic force microscopy based nanoindentation method was employed to study how the structure of cellulose microfibril packing and matrix polymers affect elastic modulus of fully hydrated primary plant cell walls. The isolated, single-layered abaxial epidermis cell wall of an onion bulb was used as a test system since the cellulose microfibril packing in this cell wall is known to vary systematically from inside to outside scales and the most abundant matrix polymer, pectin, can easily be altered through simple chemical treatments such as ethylenediaminetetraacetic acid and calcium ions. Experimental results showed that the pectin network variation has significant impacts on the cell wall modulus, and not the cellulose microfibril packing.

  8. Gaining insight into the physics of dynamic atomic force microscopy in complex environments using the VEDA simulator.

    Science.gov (United States)

    Kiracofe, Daniel; Melcher, John; Raman, Arvind

    2012-01-01

    Dynamic atomic force microscopy (dAFM) continues to grow in popularity among scientists in many different fields, and research on new methods and operating modes continues to expand the resolution, capabilities, and types of samples that can be studied. But many promising increases in capability are accompanied by increases in complexity. Indeed, interpreting modern dAFM data can be challenging, especially on complicated material systems, or in liquid environments where the behavior is often contrary to what is known in air or vacuum environments. Mathematical simulations have proven to be an effective tool in providing physical insight into these non-intuitive systems. In this article we describe recent developments in the VEDA (virtual environment for dynamic AFM) simulator, which is a suite of freely available, open-source simulation tools that are delivered through the cloud computing cyber-infrastructure of nanoHUB (www.nanohub.org). Here we describe three major developments. First, simulations in liquid environments are improved by enhancements in the modeling of cantilever dynamics, excitation methods, and solvation shell forces. Second, VEDA is now able to simulate many new advanced modes of operation (bimodal, phase-modulation, frequency-modulation, etc.). Finally, nineteen different tip-sample models are available to simulate the surface physics of a wide variety different material systems including capillary, specific adhesion, van der Waals, electrostatic, viscoelasticity, and hydration forces. These features are demonstrated through example simulations and validated against experimental data, in order to provide insight into practical problems in dynamic AFM.

  9. A review of gene-environment correlations and their implications for autism: a conceptual model.

    Science.gov (United States)

    Meek, Shantel E; Lemery-Chalfant, Kathryn; Jahromi, Laudan B; Valiente, Carlos

    2013-07-01

    A conceptual model is proposed that explains how gene-environment correlations and the multiplier effect function in the context of social development in individuals with autism. The review discusses the current state of autism genetic research, including its challenges, such as the genetic and phenotypic heterogeneity of the disorder, and its limitations, such as the lack of interdisciplinary work between geneticists and social scientists. We discuss literature on gene-environment correlations in the context of social development and draw implications for individuals with autism. The review expands upon genes, behaviors, types of environmental exposure, and exogenous variables relevant to social development in individuals on the autism spectrum, and explains these factors in the context of the conceptual model to provide a more in-depth understanding of how the effects of certain genetic variants can be multiplied by the environment to cause largely phenotypic individual differences. Using the knowledge gathered from gene-environment correlations and the multiplier effect, we outline novel intervention directions and implications. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  10. Comparative atomic-scale hydration of the ceramide and phosphocholine headgroup in solution and bilayer environments

    Science.gov (United States)

    Gillams, Richard J.; Lorenz, Christian D.; McLain, Sylvia E.

    2016-06-01

    Previous studies have used neutron diffraction to elucidate the hydration of the ceramide and the phosphatidylcholine headgroup in solution. These solution studies provide bond-length resolution information on the system, but are limited to liquid samples. The work presented here investigates how the hydration of ceramide and phosphatidylcholine headgroups in a solution compares with that found in a lipid bilayer. This work shows that the hydration patterns seen in the solution samples provide valuable insight into the preferential location of hydrating water molecules in the bilayer. There are certain subtle differences in the distribution, which result from a combination of the lipid conformation and the lipid-lipid interactions within the bilayer environment. The lipid-lipid interactions in the bilayer will be dependent on the composition of the bilayer, whereas the restricted exploration of conformational space is likely to be applicable in all membrane environments. The generalized description of hydration gathered from the neutron diffraction studies thus provides good initial estimation for the hydration pattern, but this can be further refined for specific systems.

  11. Characterization of local hydrophobicity on sapphire (0001) surfaces in aqueous environment by colloidal probe atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Tomoya; Yamazaki, Kenji; Isono, Toshinari; Ogino, Toshio, E-mail: ogino-toshio-rx@ynu.ac.jp

    2017-02-28

    Highlights: • Local hydrophobicity of phase-separated sapphire (0001) surfaces was investigated. • These surfaces are featured by coexistence of hydrophilic and hydrophobic domains. • Each domain was characterized by colloidal probe atomic force microscopy in water. • Both domains can be distinguished by adhesive forces of the probe to the surfaces. • Characterization in aqueous environment is important in bio-applications of sapphire. - Abstract: Sapphire (0001) surfaces exhibit a phase-separation into hydrophobic and hydrophilic domains upon high-temperature annealing, which were previously distinguished by the thickness of adsorbed water layers in air using atomic force microscopy (AFM). To characterize their local surface hydrophobicity in aqueous environment, we used AFM equipped with a colloidal probe and measured the local adhesive force between each sapphire domain and a hydrophilic SiO{sub 2} probe surface, or a hydrophobic polystyrene one. Two data acquisition modes for statistical analyses were used: one is force measurements at different positions of the surface and the other repeated measurement at a fixed position. We found that adhesive force measurements using the polystyrene probe allow us to distinctly separate the hydrophilic and hydrophobic domains. The dispersion in the force measurement data at different positions of the surface is larger than that in the repeated measurements at a fixed position. It indicates that the adhesive force measurement is repeatable although their data dispersion for the measurement positions is relatively large. From these results, we can conclude that the hydrophilic and hydrophobic domains on the sapphire (0001) surfaces are distinguished by a difference in their hydration degrees.

  12. Implications of fluoroquinolone contamination for the aquatic environment-A review.

    Science.gov (United States)

    Janecko, Nicol; Pokludova, Lucie; Blahova, Jana; Svobodova, Zdenka; Literak, Ivan

    2016-11-01

    Until recently, the behaviors of antibiotics and their ecotoxicological impact have been overlooked in the environment. The topic is broad and encompasses a wide range of organisms including microorganisms, algae, invertebrates, and vertebrates inhabiting various aquatic ecosystems. Changing the equilibrium of any 1 component in such systems disrupts the balance of the whole system. The manufacturing and frequent use of fluoroquinolones in human and animal medicine raises great concern over the increase of antibiotic resistance prevalence in microorganisms; however, in addition, the fate of antibiotic parent and metabolite compounds entering environmental ecosystems through various pathways raises environmental impact concerns. Research has focused on the concentration of antibiotics present in environmental samples and the acute toxicity to organisms by way of animal assessment models; however, it remains unclear what role low-level chronic exposure plays in ecotoxicological effects on lifeforms in aquatic environments. The aim of the present review was to assess the levels of fluorquinolone use in animal and human medicine, to determine the pathways of dissemination, and to highlight the ecotoxicological implications in freshwater environments. Environ Toxicol Chem 2016;35:2647-2656. © 2016 SETAC. © 2016 SETAC.

  13. Teacher interaction in psychosocial learning environments: cultural differences and their implications in science instruction

    Science.gov (United States)

    Khine, Myint Swe; Fisher, Darrell L.

    2004-01-01

    The purpose of this study was to examine interpersonal behaviour in psychosocial learning environments and to determine the associations between science students' perceptions of their interactions with their teachers, the cultural background of teachers and their attitudinal outcomes. A sample of 1188 students completed the Questionnaire on Teacher Interaction instrument. The responses to two subscales of Test of Science-related Attitudes were used as attitudinal measures. Significant associations between students' perceptions of teacher interpersonal behaviour and the cultural background of teachers were detected. The results showed that students perceived a more favourable interpersonal relationship with Western teachers in the secondary science classrooms. The students in the classes of Western teachers indicated that they enjoyed science lessons more than those in the classes of Asian teachers. Some implications for science instruction in this context are discussed.

  14. Extremophilic iron-reducing bacteria: Their implications for possible life in extraterrestrial environments

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J.; Liu, S.V.; Zhang, C.; Palumbo, A.V.; Phelps, T.J.

    1998-06-01

    Iron reduction is believed to be an early form of respiration and iron-reducing bacteria might have evolved very early on Earth. To support this hypothesis, the authors began to search for both thermophilic and psychrophilic iron-reducing bacteria because iron-reducing capacity may be a widely distributed trait if ancestral microorganisms include extremophilic iron-reducing bacteria. To date, they have obtained thermophilic Fe(III)-reducing and magnetite-forming enrichment cultures from geologically and hydrologically isolated, millions of years-old deep terrestrial subsurface samples. Three dominant bacteria were identified based on 16S ribosomal RNA gene sequences. Phylogenetical analysis indicated that these bacteria were closely related to Thermoanaerobacter ethanoliticus. Two pure thermophilic iron-reducing bacteria have been isolated and characterized from these enrichments, they also are able to degrade cellulose and xylan. Geological evidence indicated that these bacteria were separated from modern organisms for about 200 million years, and they are the oldest isolated bacteria available now. Evolutionary sequence analysis showed that the 16S rRNA genes evolved extremely slowly in these bacteria. In addition, the authors have obtained about 30 psychrophilic iron-reducing bacteria in samples from Siberia and Alaska permafrost soils, Pacific marine sediments and Hawaii deep sea water. These bacteria were also able to reduce other heavy metals. The isolation of both thermophilic and psychrophilic iron-reducing bacteria from surface and subsurface environments has significant implications for microbial evolution and for studying the origin of life in extraterrestrial environments.

  15. Contamination of the Aquatic Environment with Neonicotinoids and its Implication for Ecosystems

    Directory of Open Access Journals (Sweden)

    Francisco Sánchez-Bayo

    2016-11-01

    Full Text Available The widespread use of systemic neonicotinoid insecticides in agriculture results first in contamination of the soil of the treated crops, and secondly in the transfer of residues to the aquatic environment. The high toxicity of these insecticides to aquatic insects and other arthropods has been recognized, but there is little awareness of the impacts these chemicals have on aquatic environments and the ecosystem at large. Recent monitoring studies in several countries, however, have revealed a world-wide contamination of creeks, rivers and lakes with these insecticides, with residue levels in the low μg/L (ppb range. The current extent of aquatic contamination by neonicotinoids is reviewed first, and the findings contrasted with the known acute and chronic toxicity of neonicotinoids to various aquatic organisms. Impacts on populations and aquatic communities, mostly using mesocosms, are reviewed next to identify the communities most at risk from those that undergo little or no impact. Finally, the ecological links between aquatic and terrestrial organisms are considered. The consequences for terrestrial vertebrate species that depend mainly on this food source are discussed together with impacts on ecosystem function. Gaps in knowledge stem from difficulties in obtaining long-term experimental data that relates the effects on individual organisms to impacts on populations and ecosystems. The paper concludes with a summary of findings and the implications they have for the larger ecosystem.

  16. The Extent and Implications of the Microclimatic Conditions in the Urban Environment: A Vienna Case Study

    Directory of Open Access Journals (Sweden)

    Milena Vuckovic

    2017-01-01

    Full Text Available Recent challenges in the realm of urban studies concern better understanding of microclimatic conditions. Changes in urban climate affect cities at local and global scales, with consequences for human health, thermal comfort, building energy use, and anthropogenic emissions. The extent of these impacts may vary due to different morphologies and materials of the built environment. The present contribution summarizes the results of a multi-year effort concerned with the extent and implications of urban heat in Vienna, Austria. For this purpose, high-resolution weather data across six locations are obtained and analyzed. This allowed for an objective assessment of urban-level climatic circumstances across distinct low-density and high-density typologies. Subsequently, a systematic framework was developed for identification of essential properties of the built environment (geometric and material-related that are hypothesized to influence microclimate variation. Results point to a number of related (positive and negative correlations with microclimatic tendencies. Additionally, the impact of this location-specific weather data on building performance simulation results is evaluated. The results suggest that buildings' thermal performance is significantly influenced by location-specific microclimatic conditions with variation of mean annual heating load across locations of up to 16.1 kWhm−2·a−1. The use of location-independent weather data sources (e.g., standardized weather files for building performance estimations can, thus, result in considerable errors.

  17. Atomic phenomena in dense plasmas

    International Nuclear Information System (INIS)

    Weisheit, J.C.

    1981-03-01

    The following chapters are included: (1) the plasma environment, (2) perturbations of atomic structure, (3) perturbations of atomic collisions, (4) formation of spectral lines, and (5) dielectronic recombination

  18. DETECTION OF MOLECULAR GAS IN VOID GALAXIES: IMPLICATIONS FOR STAR FORMATION IN ISOLATED ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Das, M.; Honey, M. [Indian Institute of Astrophysics, Bangalore (India); Saito, T. [Department of Astronomy, Graduate school of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Iono, D. [Chile Observatory, NAOJ (Japan); Ramya, S., E-mail: mousumi@iiap.res.in [Shanghai Astronomical Observatory, Shanghai (China)

    2015-12-10

    We present the detection of molecular gas from galaxies located in nearby voids using the CO(1–0) line emission as a tracer. The observations were performed using the 45 m single dish radio telescope of the Nobeyama Radio Observatory. Void galaxies lie in the most underdense parts of our universe and a significant fraction of them are gas rich, late-type spiral galaxies. Although isolated, they have ongoing star formation but appear to be slowly evolving compared to galaxies in denser environments. Not much is known about their star formation properties or cold gas content. In this study, we searched for molecular gas in five void galaxies. The galaxies were selected based on their relatively high IRAS fluxes or Hα line luminosities, both of which signify ongoing star formation. All five galaxies appear to be isolated and two lie within the Bootes void. We detected CO(1–0) emission from four of the five galaxies in our sample and their molecular gas masses lie between 10{sup 8} and 10{sup 9} M{sub ⊙}. We conducted follow-up Hα imaging observations of three detected galaxies using the Himalayan Chandra Telescope and determined their star formation rates (SFRs) from their Hα fluxes. The SFR varies from 0.2 to 1 M{sub ⊙} yr{sup −1}; which is similar to that observed in local galaxies. Our study indicates that although void galaxies reside in underdense regions, their disks contain molecular gas and have SFRs similar to galaxies in denser environments. We discuss the implications of our results.

  19. Climate Change Impacts on the Built Environment in the United States and Implications for Sustainability

    Science.gov (United States)

    Quattrochi, Dale A.

    2012-01-01

    As an integral part of the National Climate Assessment (NCA), technical assessment reports for 13 regions in the U.S. that describe the scientific rationale to support climate change impacts within the purview of these regions, and provide adaptation or mitigation measures in response to these impacts. These technical assessments focus on climate change impacts on sectors that are important environmental, biophysical, and social and economic aspects of sustainability within the U.S.: Climate change science, Ecosystems and biodiversity, Water resources, Human health, Energy supply and use, Water/energy/land use, Transportation, Urban/infrastructure/vulnerability, Agriculture, Impacts of climate change on tribal/indigenous and native lands and resources, Forestry, Land use/land cover change, Rural communities development, and Impacts on biogeochemical cycles, with implications for ecosystems and biodiversity. There is a critical and timely need for the development of mitigation and adaptation strategies in response to climate change by the policy and decision making communities, to insure resiliency and sustainability of the built environment in the future.

  20. Chemical Kinetics of Hydrogen Atom Abstraction from Allylic Sites by 3O2; Implications for Combustion Modeling and Simulation.

    Science.gov (United States)

    Zhou, Chong-Wen; Simmie, John M; Somers, Kieran P; Goldsmith, C Franklin; Curran, Henry J

    2017-03-09

    Hydrogen atom abstraction from allylic C-H bonds by molecular oxygen plays a very important role in determining the reactivity of fuel molecules having allylic hydrogen atoms. Rate constants for hydrogen atom abstraction by molecular oxygen from molecules with allylic sites have been calculated. A series of molecules with primary, secondary, tertiary, and super secondary allylic hydrogen atoms of alkene, furan, and alkylbenzene families are taken into consideration. Those molecules include propene, 2-butene, isobutene, 2-methylfuran, and toluene containing the primary allylic hydrogen atom; 1-butene, 1-pentene, 2-ethylfuran, ethylbenzene, and n-propylbenzene containing the secondary allylic hydrogen atom; 3-methyl-1-butene, 2-isopropylfuran, and isopropylbenzene containing tertiary allylic hydrogen atom; and 1-4-pentadiene containing super allylic secondary hydrogen atoms. The M06-2X/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hinder rotation treatments for lower frequency modes. The G4 level of theory was used to calculate the electronic single point energies for those species to determine the 0 K barriers to reaction. Conventional transition state theory with Eckart tunnelling corrections was used to calculate the rate constants. The comparison between our calculated rate constants with the available experimental results from the literature shows good agreement for the reactions of propene and isobutene with molecular oxygen. The rate constant for toluene with O 2 is about an order magnitude slower than that experimentally derived from a comprehensive model proposed by Oehlschlaeger and coauthors. The results clearly indicate the need for a more detailed investigation of the combustion kinetics of toluene oxidation and its key pyrolysis and oxidation intermediates. Despite this, our computed barriers and rate constants retain an important internal consistency. Rate constants

  1. Effects of delocalization on intrinsic barriers for H-atom transfer: Implications for the radical hydrogen transfer reaction

    Energy Technology Data Exchange (ETDEWEB)

    Camaioni, D.M.; Autrey, S.T.; Ferris, K.F.; Franz, J.A.

    1992-08-01

    PM3 calculations of transition states (TS) for both normal H-atom transfer and radical hydrogen transfer (RHT) reactions of a a wide-variety of hydrocarbon structures have enabled development of quantitative structure-reactivity relationships. Results indicate that activation barriers for RHT reactions are large enough that thermoneutral and endothermic reactions should not compete with alternative multistep pathways.

  2. Atomic scale simulations of pyrochlore oxides with a tight-binding variable-charge model: implications for radiation tolerance.

    Science.gov (United States)

    Sattonnay, G; Tétot, R

    2014-02-05

    Atomistic simulations with new interatomic potentials derived from a tight-binding variable-charge model were performed in order to investigate the lattice properties and the defect formation energies in Gd2Ti2O7 and Gd2Zr2O7 pyrochlores. The main objective was to determine the role played by the defect stability on the radiation tolerance of these compounds. Calculations show that the titanate has a more covalent character than the zirconate. Moreover, the properties of oxygen Frenkel pairs, cation antisite defects and cation Frenkel pairs were studied. In Gd2Ti2O7 the cation antisite defect and the Ti-Frenkel pair are not stable: they evolve towards more stable defect configurations during the atomic relaxation process. This phenomenon is driven by a decrease of the Ti coordination number down to five which leads to a local atomic reorganization and strong structural distortions around the defects. These kinds of atomic rearrangements are not observed around defects in Gd2Zr2O7. Therefore, the defect stability in A2B2O7 depends on the ability of B atoms to accommodate high coordination number (higher than six seems impossible for Ti). The accumulation of structural distortions around Ti-defects due to this phenomenon could drive the Gd2Ti2O7 amorphization induced by irradiation.

  3. The Structure of Vertical Wind Shear in Tropical Cyclone Environments: Implications for Forecasting and Predictability

    Science.gov (United States)

    Finocchio, Peter M.

    shallow layers of upper-level shear. Many of the wind profiles tested in the idealized simulations have shear height or depth values on the tails of these distributions, suggesting that the environmental wind profiles around real TCs do not exhibit enough structural variability to have the clear statistical relationship to intensity change that we expected. In the final part of this dissertation, we use the reanalyzed TC environments to initialize ensembles of idealized simulations. Using a new modeling technique that allows for time-varying environments, these simulations examine the predictability implications of exposing a TC to different structures and magnitudes of vertical wind shear during its life cycle. We find that TCs in more deeply distributed vertical wind shear environments have a more uncertain intensity evolution than TCs exposed to shallower layers of upper-level shear. This higher uncertainty arises from a more marginal boundary layer environment that the deeply distributed shear establishes, which enhances the TC sensitivity to the magnitude of deep-layer shear. Simulated radar reflectivity also appears to evolve in a more uncertain fashion in environments with deeply distributed vertical shear. However, structural predictability timescales, computed as the time it takes for errors in the amplitude or phase of azimuthal asymmetries of reflectivity to saturate, are similar for wind profiles with shallow upper-level shear and deeply distributed shear. Both ensembles demonstrate predictability timescales of two to three days for the lowest azimuthal wavenumbers of amplitude and phase. As the magnitude of vertical wind shear increases to universally destructive levels, structural and intensity errors begin to decrease. Shallow upper-level shear primes the TC for a more pronounced recovery in the predictability of the wavenumber-one precipitation structure in stronger shear. The recovered low-wavenumber predictability of TC precipitation structure and the

  4. China's coke industry: Recent policies, technology shift, and implication for energy and the environment

    International Nuclear Information System (INIS)

    Huo, Hong; Lei, Yu; Zhang, Qiang; Zhao, Lijian; He, Kebin

    2012-01-01

    China is the largest coke producer in the world, accounting for over 60% of the world coke production, which makes the coke industry in China a significant coal consumer and air pollutant emitter. Recently, China has taken a series of measures to improve energy efficiency and reduce emissions from the coke industry, including eliminating old and low energy-efficiency coking technologies, promoting advanced technologies, and strengthening energy and environmental requirements on coking processes. As a consequence, China's coke industry is experiencing an unprecedented technology shift, which was characterized by the elimination of old, inefficient, and polluting indigenous ovens and small machinery ones within 10 years. This study examines the policies and the prompt technology shift in China's coke industry, as well as the associated energy and environmental effects, and discusses the implications with respect to the development of the coke industry in China towards a more efficient and clean future. As China sets stricter requirements on energy efficiency and the ambient environment, a more significant change focusing on technologies of energy saving and emission reduction is urgently needed at present. Those mature technologies, including coke dry quenching, coke oven gas recycle, fine particle removal, etc., should be enforced in the near future. - Highlights: ► With 60% of world coke output, China's coke making has big energy/pollution issues. ► Actions were taken to improve energy and environmental performance of coke plants. ► China's coke industry is experiencing an unprecedented technology shift. ► Another shift, focusing on technologies of energy and emission saving, is needed. ► More measurement studies on coking emissions are needed given the importance.

  5. Comparison of photothermal and piezoacoustic excitation methods for frequency and phase modulation atomic force microscopy in liquid environments

    Directory of Open Access Journals (Sweden)

    A. Labuda

    2011-06-01

    Full Text Available In attempting to perform frequency modulation atomic force microscopy (FM-AFM in liquids, a non-flat phase transfer function in the self-excitation system prevents proper tracking of the cantilever natural frequency. This results in frequency-and-phase modulation atomic force microscopy (FPM-AFM which lies in between phase modulation atomic force microscopy (PM-AFM and FM-AFM. We derive the theory necessary to recover the conservative force and damping in such a situation, where standard FM-AFM theory no longer applies. Although our recovery procedure applies to all cantilever excitation methods in principle, its practical implementation may be difficult, or even impossible, if the cantilever is driven piezoacoustically. Specifically, we contrast the piezoacoustic excitation method to the photothermal method in the context of force spectroscopy of hydration structures at the mica-water interface. The results clearly demonstrate that photothermal excitation is superior to piezoacoustic excitation, as it allows for accurate quantitative interpretation of the acquired data.

  6. Environment

    DEFF Research Database (Denmark)

    Valentini, Chiara

    2017-01-01

    The term environment refers to the internal and external context in which organizations operate. For some scholars, environment is defined as an arrangement of political, economic, social and cultural factors existing in a given context that have an impact on organizational processes and structures....... For others, environment is a generic term describing a large variety of stakeholders and how these interact and act upon organizations. Organizations and their environment are mutually interdependent and organizational communications are highly affected by the environment. This entry examines the origin...... and development of organization-environment interdependence, the nature of the concept of environment and its relevance for communication scholarships and activities....

  7. Molecular dynamics simulations of the d(CCAACGTTGG)2 decamer in crystal environment: comparison of atom-centered charge, extra-point and polarizable force fields.

    Science.gov (United States)

    Baucom, Jason; Transue, Thomas; Fuentes-Cabrera, Miguel; Krahn, Joseph; Darden, Thomas; Sagui, Celeste

    2004-03-01

    Molecular dynamics simulations of the DNA duplex d(CCAACGTTGG)2 were used to study the relationship between DNA sequence and structure. Three different force fields were used: a traditional description based on atomic point charges, a polarizable force field and an ``extra-point" force field (with additional charges on extra-nuclear sites). It is found that in crystal environment all the force fields reproduce fairly well the sequence-dependent features of the experimental structure. The polarizable force fields, however, outperforms the other two, pointing out to the need of the inclusion of polarization for accurate descriptions of DNA.

  8. Marine biofouling and its implications in the use of seawater as a heat transfer fluid in Madras Atomic Power Station

    International Nuclear Information System (INIS)

    Nair, K.V.K.; Venugopalan, V.P.

    1996-01-01

    Even though the problem of fouling is quite severe in the tropics because of rich diversity of species and longer periods available for breeding activity, most of the literature is from the temperate waters. In this paper, an attempt is made to illustrate the potential of biofouling to compromise the economical operation of coastal power plants by taking Madras Atomic Power Station (MAPS) as an example. The significance of acquiring information on biological aspects of the fouling species in successfully combating the problems is also highlighted. 3 refs., 3 tabs., 1 fig

  9. Atom trap loss, elastic collisions, and technology

    Science.gov (United States)

    Booth, James

    2012-10-01

    The study of collisions and scattering has been one of the most productive approaches for modern physics, illuminating the fundamental structure of crystals, surfaces, atoms, and sub-atomic particles. In the field of cold atoms, this is no less true: studies of cold atom collisions were essential to the production of quantum degenerate matter, the formation of cold molecules, and so on. Over the past few years it has been my delight to investigate elastic collisions between cold atoms trapped in either a magneto-optical trap (MOT) or a magnetic trap with hot, background gas in the vacuum environment through the measurement of the loss of atoms from the trap. Motivated by the goal of creating cold atom-based technology, we are deciphering what the trapped atoms are communicating about their environment through the observed loss rate. These measurements have the advantages of being straightforward to implement and they provide information about the underlying, fundamental inter-atomic processes. In this talk I will present some of our recent work, including the observation of the trap depth dependence on loss rate for argon-rubidium collisions. The data follow the computed loss rate curve based on the long-range Van der Waals interaction between the two species. The implications of these findings are exciting: trap depths can be determined from the trap loss measurement under controlled background density conditions; observation of trap loss rate in comparison to models for elastic, inelastic, and chemical processes can lead to improved understanding and characterization of these fundamental interactions; finally the marriage of cold atoms with collision modeling offers the promise of creating a novel pressure sensor and pressure standard for the high and ultra-high vacuum regime.

  10. Adsorption of carbon monoxide on small aluminum oxide clusters: Role of the local atomic environment and charge state on the oxidation of the CO molecule

    Science.gov (United States)

    Ornelas-Lizcano, J. C.; Guirado-López, R. A.

    2015-03-01

    We present extensive density functional theory (DFT) calculations dedicated to analyze the adsorption behavior of CO molecules on small AlxOy± clusters. Following the experimental results of Johnson et al. [J. Phys. Chem. A 112, 4732 (2008)], we consider structures having the bulk composition Al2O3, as well as smaller Al2O2 and Al2O units. Our electron affinity and total energy calculations are consistent with aluminum oxide clusters having two-dimensional rhombus-like structures. In addition, interconversion energy barriers between two- and one-dimensional atomic arrays are of the order of 1 eV, thus clearly defining the preferred isomers. Single CO adsorption on our charged AlxOy± clusters exhibits, in general, spontaneous oxygen transfer events leading to the production of CO2 in line with the experimental data. However, CO can also bind to both Al and O atoms of the clusters forming aluminum oxide complexes with a CO2 subunit. The vibrational spectra of AlxOy + CO2 provides well defined finger prints that may allow the identification of specific isomers. The AlxOy+ clusters are more reactive than the anionic species and the final Al2O+ + CO reaction can result in the production of atomic Al and carbon dioxide as observed from experiments. We underline the crucial role played by the local atomic environment, charge density distribution, and spin-multiplicity on the oxidation behavior of CO molecules. Finally, we analyze the importance of coadsorption and finite temperature effects by performing DFT Born-Oppenheimer molecular dynamics. Our calculations show that CO oxidation on AlxOy+ clusters can be also promoted by the binding of additional CO species at 300 K, revealing the existence of fragmentation processes in line with the ones experimentally inferred.

  11. Effect of radioactive pollution of the environment on soil fauna in the region of the Chernobyl atomic station

    International Nuclear Information System (INIS)

    Krivolutskii, D.A.; Pokarzhevskii, A.D.; Usachev, V.L.; Shein, G.N.; Nadvornyi, V.G.; Viktorov, A.G.

    1991-01-01

    Investigations of soil fauna populations within a 30-km zone around the Chernobyl Atomic Energy Station between July 1986 and October 1988 showed a marked decrease in the first year after the accident in the species composition of soil microarthropods and in the abundance of their populations in soils of the local pine [Pinus] forests. The soils of agroecosystems showed a decrease in young individuals. In the second year after the accident, the populations of settled species of soil fauna recovered slowly, and recovery of the total abundance of soil fauna in the 30-km zone occurred due to populations of migrating species. After 2-2.5 years, the abundance and biomass of soil fauna populations in polluted areas had recovered

  12. Students' Conception of Learning Environment and Their Approach to Learning and Its Implication on Quality Education

    Science.gov (United States)

    Belaineh, Matheas Shemelis

    2017-01-01

    Quality of education in higher institutions can be affected by different factors. It partly rests on the learning environment created by teachers and the learning approach students are employing during their learning. The main purpose of this study is to examine the learning environment at Mizan Tepi University from students' perspective and their…

  13. New insight into the observation of spectroscopic strength reduction in atomic nuclei: implication for the physical meaning of spectroscopic factors.

    Science.gov (United States)

    Timofeyuk, N K

    2009-12-11

    Experimental studies of one-nucleon knockout from magic nuclei suggest that their nucleon orbits are not fully occupied. This conflicts a commonly accepted view of the shell closure associated with such nuclei. The conflict can be reconciled if the overlap between initial and final nuclear states in a knockout reaction are calculated by a nonstandard method. The method employs an inhomogeneous equation based on correlation-dependent effective nucleon-nucleon interactions and allows the simplest wave functions, in which all nucleons occupy only the lowest nuclear orbits, to be used. The method also reproduces the recently established relation between reduction of spectroscopic strength, observed in knockout reactions on other nuclei, and nucleon binding energies. The implication of the inhomogeneous equation method for the physical meaning of spectroscopic factors is discussed.

  14. Environment

    Science.gov (United States)

    2005-01-01

    biodiversity. Consequently, the major environmental challenges facing us in the 21st century include: global climate change , energy, population and food...technological prowess, and security interests. Challenges Global Climate Change – Evidence shows that our environment and the global climate ... urbanization will continue to pressure the regional environment . Although most countries have environmental protection ministries or agencies, a lack of

  15. Policy, Research and Residents’ Perspectives on Built Environments Implicated in Heart Disease: A Concept Mapping Approach

    Directory of Open Access Journals (Sweden)

    Ivana Stankov

    2017-02-01

    Full Text Available An underrepresentation of stakeholder perspectives within urban health research arguably limits our understanding of what is a multi-dimensional and complex relationship between the built environment and health. By engaging a wide range of stakeholders using a participatory concept mapping approach, this study aimed to achieve a more holistic and nuanced understanding of the built environments shaping disease risk, specifically cardiometabolic risk (CMR. Moreover, this study aimed to ascertain the importance and changeability of identified environments through government action. Through the concept mapping process, community members, researchers, government and non-government stakeholders collectively identified eleven clusters encompassing 102 built environmental domains related to CMR, a number of which are underrepresented within the literature. Among the identified built environments, open space, public transportation and pedestrian environments were highlighted as key targets for policy intervention. Whilst there was substantive convergence in stakeholder groups’ perspectives concerning the built environment and CMR, there were disparities in the level of importance government stakeholders and community members respectively assigned to pedestrian environments and street connectivity. These findings support the role of participatory methods in strengthening how urban health issues are understood and in affording novel insights into points of action for public health and policy intervention.

  16. Policy, Research and Residents' Perspectives on Built Environments Implicated in Heart Disease: A Concept Mapping Approach.

    Science.gov (United States)

    Stankov, Ivana; Howard, Natasha J; Daniel, Mark; Cargo, Margaret

    2017-02-09

    An underrepresentation of stakeholder perspectives within urban health research arguably limits our understanding of what is a multi-dimensional and complex relationship between the built environment and health. By engaging a wide range of stakeholders using a participatory concept mapping approach, this study aimed to achieve a more holistic and nuanced understanding of the built environments shaping disease risk, specifically cardiometabolic risk (CMR). Moreover, this study aimed to ascertain the importance and changeability of identified environments through government action. Through the concept mapping process, community members, researchers, government and non-government stakeholders collectively identified eleven clusters encompassing 102 built environmental domains related to CMR, a number of which are underrepresented within the literature. Among the identified built environments, open space, public transportation and pedestrian environments were highlighted as key targets for policy intervention. Whilst there was substantive convergence in stakeholder groups' perspectives concerning the built environment and CMR, there were disparities in the level of importance government stakeholders and community members respectively assigned to pedestrian environments and street connectivity. These findings support the role of participatory methods in strengthening how urban health issues are understood and in affording novel insights into points of action for public health and policy intervention.

  17. Simultaneous Laser-induced Fluorescence of Nitric Oxide and Atomic Oxygen in the Hypersonic Materials Environment Test System Arcjet Facility

    Science.gov (United States)

    Johansen, Craig; Lincoln, Daniel; Bathel, Brett; Inman, Jennifer; Danehy, Paul

    2014-01-01

    Simultaneous nitric oxide (NO) and atomic oxygen (O) laser induced fluorescence (LIF) experiments were performed in the Hypersonic Materials Environmental Test System (HYMETS) facility at the NASA Langley Research Center. The data serves as an experimental database for validation for chemical and thermal nonequilibrium models used in hypersonic flows. Measurements were taken over a wide range of stagnation enthalpies (6.7 - 18.5 MJ/kg) using an Earth atmosphere simulant with a composition of 75% N2, 20% O2, and 5% Ar (by volume). These are the first simultaneous measurements of NO and O LIF to be reported in literature for the HYMETS facility. The maximum O LIF mean signal intensity was observed at a stagnation enthalpy of approximately 12 MJ/kg while the maximum NO LIF mean signal intensity was observed at a stagnation enthalpy of 6.7 MJ/kg. Experimental results were compared to simple fluorescence model that assumes equilibrium conditions in the plenum and frozen chemistry in the isentropic nozzle expansion (Mach 5). The equilibrium calculations were performed using CANTERA v2.1.1 with 16 species. The fluorescence model captured the correlation in mean O and NO LIF signal intensities over the entire range of stagnation enthalpies tested. Very weak correlations between single-shot O and NO LIF intensities were observed in the experiments at all of the stagnation enthalpy conditions.

  18. Determination of Gold in Various Environment Samples by Flame Atomic Absorption Spectrometry Using Dispersive Liquid–Liquid Microextraction Sampling

    Directory of Open Access Journals (Sweden)

    Şerife Saçmacı

    2015-07-01

    Full Text Available A new dispersive liquid–liquid microextraction separation/preconcentration procedure as a rapid sample-preparation technique is proposed for detection of ultra trace amounts of Au(III in various media by flame atomic absorption spectrometry using 1,5-diphenyl-1,3,5-pentanetrione as chelating agent. Carbon tetrachloride and methanol were used as extraction and dispersive solvents, respectively. Various parameters that affect the extraction efficiency such as pH, centrifugation rate and time, chelating agent concentration and sampling volume on the recovery of Au(III were investigated. Under optimum conditions, the enhancement factor of 750, relative standard deviation of 2.7 % and calibration graphs obtained in the concentration range of 0.04–5.6 μg L−1 for gold were obtained. The limit of detection was 1.1 ng L−1. The accuracy of the method was performed by analysis of the certified reference material (CDN-PGMS-10. The developed method was applied successfully to the determination of gold in the catalytic converter, anode slime, ore and seawater samples. The results show that dispersive liquid–liquid microextraction procedure is sensitive, rapid, simple and safe for the separation/preconcentration of gold from complex sample media.

  19. State Authenticity as Fit to Environment: The Implications of Social Identity for Fit, Authenticity, and Self-Segregation.

    Science.gov (United States)

    Schmader, Toni; Sedikides, Constantine

    2017-10-01

    People seek out situations that "fit," but the concept of fit is not well understood. We introduce State Authenticity as Fit to the Environment (SAFE), a conceptual framework for understanding how social identities motivate the situations that people approach or avoid. Drawing from but expanding the authenticity literature, we first outline three types of person-environment fit: self-concept fit, goal fit, and social fit. Each type of fit, we argue, facilitates cognitive fluency, motivational fluency, and social fluency that promote state authenticity and drive approach or avoidance behaviors. Using this model, we assert that contexts subtly signal social identities in ways that implicate each type of fit, eliciting state authenticity for advantaged groups but state inauthenticity for disadvantaged groups. Given that people strive to be authentic, these processes cascade down to self-segregation among social groups, reinforcing social inequalities. We conclude by mapping out directions for research on relevant mechanisms and boundary conditions.

  20. Implications of the New Manufacturing Environment for Management Control System Design

    NARCIS (Netherlands)

    Van Veen-Dirks, P.M.G.

    1998-01-01

    The modern manufacturing environment is characterized by intense international competition, rapid product innovation, turnover and obsolescence, increased use of automation, and significant organizational changes in response to new manufacturing technologies.It is generally accepted that these

  1. Entrepreneurs' Perceptions of the State Implication in the Business Environment Modelling in Romania

    Directory of Open Access Journals (Sweden)

    Ovidiu NICOLESCU

    2013-02-01

    Full Text Available One of the main economic purposes of state administration in every country is to ensure an enabling business environment. The study has two main objectives: first, to reveal and analyze the perceptions of Romanian SMEs – 99.9% of economic companies – regarding the quality of business environment, its main opportunities and difficulties; second, to evaluate the capacity of the Romanian government to face economic crisis and its consequences. The analysis is based on the interviews of 1723 SMEs entrepreneurs and managers in 2011. We have identified a predominantly unfavorable Romanian business environment and a low capacity to face the complex elements associated with economic crisis. Conclusions are grouped at three levels of state administration – national, local and sectorial – and followed by a set of recommendations regarding the improvement of business environment.

  2. Biofuel production and implications for land use, food production and environment in India

    Energy Technology Data Exchange (ETDEWEB)

    Ravindranath, N.H.; Sita Lakshmi, C.; Manuvie, Ritumbra [Center for Sustainable Technologies, Indian Institute of Science, Bangalore 560012 (India); Balachandra, P., E-mail: patilb@mgmt.iisc.ernet.in [Center for Sustainable Technologies, Indian Institute of Science, Bangalore 560012 (India)

    2011-10-15

    There is a large interest in biofuels in India as a substitute to petroleum-based fuels, with a purpose of enhancing energy security and promoting rural development. India has announced an ambitious target of substituting 20% of fossil fuel consumption by biodiesel and bioethanol by 2017. India has announced a national biofuel policy and launched a large program to promote biofuel production, particularly on wastelands: its implications need to be studied intensively considering the fact that India is a large developing country with high population density and large rural population depending upon land for their livelihood. Another factor is that Indian economy is experiencing high growth rate, which may lead to enhanced demand for food, livestock products, timber, paper, etc., with implications for land use. Studies have shown that area under agriculture and forest has nearly stabilized over the past 2-3 decades. This paper presents an assessment of the implications of projected large-scale biofuel production on land available for food production, water, biodiversity, rural development and GHG emissions. The assessment will be largely focused on first generation biofuel crops, since the Indian program is currently dominated by these crops. Technological and policy options required for promoting sustainable biofuel production will be discussed.

  3. Biofuel production and implications for land use, food production and environment in India

    International Nuclear Information System (INIS)

    Ravindranath, N.H.; Sita Lakshmi, C.; Manuvie, Ritumbra; Balachandra, P.

    2011-01-01

    There is a large interest in biofuels in India as a substitute to petroleum-based fuels, with a purpose of enhancing energy security and promoting rural development. India has announced an ambitious target of substituting 20% of fossil fuel consumption by biodiesel and bioethanol by 2017. India has announced a national biofuel policy and launched a large program to promote biofuel production, particularly on wastelands: its implications need to be studied intensively considering the fact that India is a large developing country with high population density and large rural population depending upon land for their livelihood. Another factor is that Indian economy is experiencing high growth rate, which may lead to enhanced demand for food, livestock products, timber, paper, etc., with implications for land use. Studies have shown that area under agriculture and forest has nearly stabilized over the past 2-3 decades. This paper presents an assessment of the implications of projected large-scale biofuel production on land available for food production, water, biodiversity, rural development and GHG emissions. The assessment will be largely focused on first generation biofuel crops, since the Indian program is currently dominated by these crops. Technological and policy options required for promoting sustainable biofuel production will be discussed.

  4. Use of Disjunctive Response Requirements in Dual-Task Environments: Implications for Automation.

    Science.gov (United States)

    1986-05-01

    responding for use within a multitask environment. The Disjunctive Response Psychologists, from the time of Donders (1868/1969), have typically classified...these questions are necessary before the usefulness of employing disjunctive response requirements in a multitask environment would be warranted. The...psychology classes at the University of New Mexico participated in this experiment for extra credit towards their course grades as well as a cash

  5. Implications of global climate change for the assessment and management of human health risks of chemicals in the natural environment.

    Science.gov (United States)

    Balbus, John M; Boxall, Alistair B A; Fenske, Richard A; McKone, Thomas E; Zeise, Lauren

    2013-01-01

    Global climate change (GCC) is likely to alter the degree of human exposure to pollutants and the response of human populations to these exposures, meaning that risks of pollutants could change in the future. The present study, therefore, explores how GCC might affect the different steps in the pathway from a chemical source in the environment through to impacts on human health and evaluates the implications for existing risk-assessment and management practices. In certain parts of the world, GCC is predicted to increase the level of exposure of many environmental pollutants due to direct and indirect effects on the use patterns and transport and fate of chemicals. Changes in human behavior will also affect how humans come into contact with contaminated air, water, and food. Dietary changes, psychosocial stress, and coexposure to stressors such as high temperatures are likely to increase the vulnerability of humans to chemicals. These changes are likely to have significant implications for current practices for chemical assessment. Assumptions used in current exposure-assessment models may no longer apply, and existing monitoring methods may not be robust enough to detect adverse episodic changes in exposures. Organizations responsible for the assessment and management of health risks of chemicals therefore need to be more proactive and consider the implications of GCC for their procedures and processes. Copyright © 2012 SETAC.

  6. An atomic string model for a screw dislocation in iron: Implications for the development of interatomic potentials

    International Nuclear Information System (INIS)

    Gilbert, M.R.; Dudarev, S.L.; Chiesa, S.; Derlet, P.M.

    2009-01-01

    Thermally activated motion of screw dislocations is the rate-determining mechanism for plastic deformation and fracture of body centred cubic (bcc) metals and alloys. Recent experimental observations by S.G. Roberts' group at Oxford showed that ductile-brittle behaviour of bcc vanadium, tungsten, pure iron, and iron-chromium alloys is controlled by an Arrhenius process in which the energy for thermal activation is proportional to the formation energy for a double kink on a b= 1/2 screw dislocation, where b is the Burgers vector of the dislocation. Interpreting these experimental observations and extending the analysis to the case of irradiated materials requires developing a full quantitative treatment for perfect and kinked screw dislocations. Modelling screw dislocations also presents a challenge for the development of interatomic potentials. Recent density functional theory (DFT) calculations have revealed that the ground-state structure of the core of screw dislocations in all the bcc transition metals is non-degenerate and symmetric, whereas inter-atomic potentials used in molecular dynamics simulations for these metals often predict a degenerate, symmetry-broken core-structure. In this work we show how, by treating the structure of a screw dislocation within a multistring Frenkel-Kontorova model, we can develop a criterion that guarantees the correct symmetric core of the dislocation. Extending this treatment, we find a systematic recipe for constructing Finnis-Sinclair-type potentials that are able, as a matter of routine, produce non-degenerate core structures of 1/2 screw dislocations. Modelling thermally activated mobility of screw dislocations also requires that the transition pathway between stable core positions of a dislocation is accurately reproduced. DFT data indicates that the shape of the 'Peierls energy barrier' is a single-hump curve, including transitional configurations close to the so-called 'hard' structure. Interatomic potentials have, up

  7. Living in contained environments: Research implications from undersea habitats. [undersea habitats

    Science.gov (United States)

    Helmreich, Robert L.

    1986-01-01

    A cost-reward model is used to frame a discussion of differences in observed behavior of individuals and groups in confined environments. It has been observed that the high cost of functioning in a stressful environment is likely to produce poor performance when anticipated rewards are low but that participants can manage the stress and achieve high performance if they anticipate high rewards. The high-reward environment is exemplified by early undersea habitats such as Sealab and Tektite and by early space missions. Other aspects of behavior occur in all confined environments and point to an important area for future research. Of particular interest are intergroup conflicts arising between the confined group and its external control. Also, individual differences in personality seem always to have an impact in confined environments. Recent research has focused on: (1) predicting performance and adjustment based on instrumental and expressive aspects of the self; (2) the differential predictive power of achievement striving and irritation/irritability in Type A personalities; and (3) the nature and role of leadership in small, isolated groups.

  8. Development of built environment and its implication on flood risk in ...

    African Journals Online (AJOL)

    The increasing frequency of flood events in urban areas and its devastating impact on lives, properties, resources and the environment as a whole has posed a serious concern to environmental scientist the world over. There are many different perspectives regarding factors responsible for flood risk in urban areas, which ...

  9. Digital Games as Multirepresentational Environments for Science Learning: Implications for Theory, Research, and Design

    Science.gov (United States)

    Virk, Satyugjit; Clark, Douglas; Sengupta, Pratim

    2015-01-01

    Environments in which learning involves coordinating multiple external representations (MERs) can productively support learners in making sense of complex models and relationships. Educational digital games provide an increasing popular medium for engaging students in manipulating and exploring such models and relationships. This article applies…

  10. Spatial perception changes associated with space flight: implications for adaptation to altered inertial environments.

    Science.gov (United States)

    Parker, Donald E

    2003-01-01

    Preparation for extended travel by astronauts within the Solar System, including a possible manned mission to Mars, requires more complete understanding of adaptation to altered inertial environments. Improved understanding is needed to support development and evaluation of interventions to facilitate adaptations during transitions between those environments. Travel to another planet escalates the adaptive challenge because astronauts will experience prolonged exposure to microgravity before encountering a novel gravitational environment. This challenge would have to be met without ground support at the landing site. Evaluation of current adaptive status as well as intervention efficacy can be performed using perceptual, eye movement and postural measures. Due to discrepancies of adaptation magnitude and time-course among these measures, complete understanding of adaptation processes, as well as intervention evaluation, requires examination of all three. Previous research and theory that provide models for comprehending adaptation to altered inertial environments are briefly examined. Reports from astronauts of selected pre- in- and postflight self-motion illusions are described. The currently controversial tilt-translation reinterpretation hypothesis is reviewed and possible resolutions to the controversy are proposed. Finally, based on apparent gaps in our current knowledge, further research is proposed to achieve a more complete understanding of adaptation as well as to develop effective counter-measures.

  11. Designing discovery learning environments: process analysis and implications for designing an information system

    NARCIS (Netherlands)

    Pieters, Julius Marie; Limbach, R.; de Jong, Anthonius J.M.

    2004-01-01

    A systematic analysis of the design process of authors of (simulation based) discovery learning environments was carried out. The analysis aimed at identifying the design activities of authors and categorising knowledge gaps that they experience. First, five existing studies were systematically

  12. Human-Computer Interaction (HCI) in Educational Environments: Implications of Understanding Computers as Media.

    Science.gov (United States)

    Berg, Gary A.

    2000-01-01

    Reviews literature in the field of human-computer interaction (HCI) as it applies to educational environments. Topics include the origin of HCI; human factors; usability; computer interface design; goals, operations, methods, and selection (GOMS) models; command language versus direct manipulation; hypertext; visual perception; interface…

  13. The natural environment and human development: implications for handicapped children in urban settings

    Science.gov (United States)

    Dennis A. Vinton; Donald E. Hawkins

    1977-01-01

    This review of literature is intended to promote awareness of the needs of the 15 percent of the nation's children and youth who are afflicted with some form of handicap. It is imperative that those who design children's programs that utilize natural environments understand the special problems of handicapped children.

  14. Gene-environment interactions in early life and adulthood : implications for cocaine intake

    NARCIS (Netherlands)

    Veen, Rixt van der

    2008-01-01

    The objective of the research described in this thesis was to demonstrate the role of gene-environment interactions in the emergence of individual differences in cocaine use. For this purpose we used two inbred mouse strains, the C57Bl/6 (C57) and DBA/2 (DBA), which are known to differ in

  15. The Performance Implications of Fit among Environment, Strategy, Structure, Control System and Social Performance

    Directory of Open Access Journals (Sweden)

    Hasan Fauzi

    2009-12-01

    domain will be contingent upon strategic behaviors, which are behaviors of members in an organization. The paper integrates the contextual variables including business environment, strategy, organization structure, and control system with corporate performance by using corporate social performance as moderating variable by means of a recent literatures study from strategic management and accounting field.

  16. Development of built environment and its implication on flood risk in ...

    African Journals Online (AJOL)

    Saidu

    This paper examines the impact of built environment on the increasing flood occurrences in Gombe Metropolis in Nigeria. Data was essentially collected through questionnaire survey and analyzed using statistical model so as to discover the main factors causing flood in the metropolis. A multi-stage sampling technique was.

  17. The energetic implications of precocial development for three shorebird species breeding in a warm environment

    NARCIS (Netherlands)

    Tjorve, K. M. C.; Underhill, L. G.; Visser, G. H.

    We investigated the effect of body size, parental behaviour and timing of breeding on the chick growth and energetics of three precocial shorebird (Charadrii) species in a warm sub-tropical environment: the Kittlitz's Plover Charadrius pecuarius, Blacksmith Lapwing Vanellus armatus, and Crowned

  18. Biota and Biomolecules in Extreme Environments on Earth: Implications for Life Detection on Mars

    Directory of Open Access Journals (Sweden)

    Joost W. Aerts

    2014-10-01

    Full Text Available The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces, particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detection on Mars, it is crucial to investigate analogue environments on Earth that resemble best past and present Mars conditions. Terrestrial extreme environments offer a rich source of information allowing us to determine how extreme conditions affect life and molecules associated with it. Extremophilic organisms have adapted to the most stunning conditions on Earth in environments with often unique geological and chemical features. One challenge in detecting biomarkers is to optimize extraction, since organic molecules can be low in abundance and can strongly adsorb to mineral surfaces. Methods and analytical tools in the field of life science are continuously improving. Amplification methods are very useful for the detection of low concentrations of genomic material but most other organic molecules are not prone to amplification methods. Therefore, a great deal depends on the extraction efficiency. The questions “what to look for”, “where to look”, and “how to

  19. Biota and biomolecules in extreme environments on Earth: implications for life detection on Mars.

    Science.gov (United States)

    Aerts, Joost W; Röling, Wilfred F M; Elsaesser, Andreas; Ehrenfreund, Pascale

    2014-10-13

    The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detection on Mars, it is crucial to investigate analogue environments on Earth that resemble best past and present Mars conditions. Terrestrial extreme environments offer a rich source of information allowing us to determine how extreme conditions affect life and molecules associated with it. Extremophilic organisms have adapted to the most stunning conditions on Earth in environments with often unique geological and chemical features. One challenge in detecting biomarkers is to optimize extraction, since organic molecules can be low in abundance and can strongly adsorb to mineral surfaces. Methods and analytical tools in the field of life science are continuously improving. Amplification methods are very useful for the detection of low concentrations of genomic material but most other organic molecules are not prone to amplification methods. Therefore, a great deal depends on the extraction efficiency. The questions "what to look for", "where to look", and "how to look for it" require more of

  20. Human-use antibacterial residues in the natural environment of China: implication for ecopharmacovigilance.

    Science.gov (United States)

    Wang, Jun; He, Bingshu; Hu, Xiamin

    2015-06-01

    Antibacterial residues in the natural environment have been of increasing concern due to their impact on bacteria resistance development and toxicity to natural communities and ultimately to public health. China is a large country with high production and consumption of antibacterials for its population growth and economic development in recent years. In this article, we summarized the current situation of human-use antibacterial pollution in Chinese water (wastewaters, natural and drinking waters) and solid matrices (sludge, sediment, and soil) reported in 33 peer-reviewed papers. We found that, although there are adequate wastewater treatment systems in China, human-use antibacterial residues in the natural environment were reported almost throughout the whole country. Three most frequently prescribed classes of antibacterials in China, including quinolones, macrolides, and β-lactam, were also the predominant classes of residues in Chinese environment, manifested as the high concentration and detection frequency. In view of this alarming situation, we have presented that ecopharmacovigilance (EPV) might be implemented in the antibacterial drug administration of China, as the active participation of the pharmaceutical industry and drug regulatory authorities from the diffuse source of antibacterial pollution. Considering EPV experience of developed countries together with the actual conditions of China, we have identified some approaches that can be taken, including:• Focus on education;• Further strengthening and persevering the antibacterial stewardship strategies and pharmaceutical take-back programs in China;• Designing greener antibacterials with better degradability in the environment;• Implementing environmental risk assessment prior to launch of new drugs;• Strengthening collaboration in EPV-related areas.

  1. Considering the Ethical Implications of Space Exploration and Potential Impacts on Planetary Environments and Possible Indigenous Life

    Science.gov (United States)

    Race, Margaret

    Since the early days of the Outer Space Treaty, a primary concern of planetary protection policy has been to avoid contamination of planetary environments by terrestrial microbes that could compromise current or subsequent scientific investigations, particularly those searching for indigenous life. Over the past decade robotic missions and astrobiological research have greatly increased our understanding of diverse planetary landscapes and altered our views about the survivability of terrestrial organisms in extreme environments. They have also expanded notions about the prospect for finding evidence of extraterrestrial life. Recently a number of different groups, including the COSPAR Planetary Protection Workshop in Montreal (January 2008), have questioned whether it is advisable to re-examine current biological planetary protection policy in light of the ethical implications and responsibilities to preserve planetary environments and possible indigenous life. This paper discusses the issues and concerns that have led to recent recommendations for convening an international workshop specifically to discuss planetary protection policy and practices within a broader ethical and practical framework, and to consider whether revisions to policy and practices should be made. In addition to including various international scientific and legal organizations and experts in such a workshop, it will be important to find ways to involve the public in these discussions about ethical aspects of planetary exploration.

  2. Adolescent Age Moderates Genetic and Environmental Influences on Parent-Adolescent Positivity and Negativity: Implications for Genotype-Environment Correlation

    Science.gov (United States)

    Marceau, Kristine; Knopik, Valerie S.; Neiderhiser, Jenae M.; Lichtenstein, Paul; Spotts, Erica L.; Ganiban, Jody M.; Reiss, David

    2015-01-01

    In the present study we examined how genotype-environment correlation processes differ as a function of adolescent age. We tested whether adolescent age moderates genetic and environmental influences on positivity and negativity in mother-adolescent and father-adolescent relationships using parallel samples of twin parents from the Twin and Offspring Study in Sweden and twin/sibling adolescents from the Nonshared Environment in Adolescent Development Study. We inferred differences in the role of passive and non-passive genotype-environment correlation based on biometric moderation findings. Findings indicated that non-passive rGE played a stronger role for positivity in mother- and father- adolescent relationships in families with older adolescents than families with younger adolescents, and that passive rGE played a stronger role for positivity in the mother-adolescent relationship in families with younger adolescents than in families with older adolescents. Implications of these findings for the timing and targeting of interventions on family relationships are discussed. PMID:25924807

  3. Shallow transient liquid water environments on present-day mars, and their implications for life

    Science.gov (United States)

    Jones, Eriita G.

    2018-05-01

    The identification and characterisation of subsurface liquid water environments on Mars are of high scientific interest. Such environments have the potential to support microbial life, and, more broadly, to develop our understanding of the habitability of planets and moons beyond Earth. Given our current state of knowledge of life on Earth, three pre-requisites are necessary for an environment to be considered 'habitable' and therefore capable of supporting terrestrial-like life: energy, biogenic elements, and liquid water with a sufficiently high water activity. The surface of Mars today is predominately cold and dry, and any liquid water exposed to the atmosphere will vaporise or freeze on timescales of hours to days. These conditions have likely persisted for much of the last 10 million years, and perhaps longer. Despite this, briny liquid water flows (Recurrent Slope Linea) have been observed in a number of locations in the present-day. This review examines evidence from the Phoenix Lander (2008) and the Mars Science Laboratory (2012-current), to assess the occurrence of habitable conditions in the shallow Martian regolith. It will be argued that shallow, transient, liquid water brines are potentially habitable by microbial life, are likely a widespread occurrence on Mars, and that future exploration aimed at finding present-day habitable conditions and potential biology should 'follow the salt'.

  4. The Legionella pneumophila kai operon is implicated in stress response and confers fitness in competitive environments

    Science.gov (United States)

    Loza-Correa, Maria; Sahr, Tobias; Rolando, Monica; Daniels, Craig; Petit, Pierre; Skarina, Tania; Valero, Laura Gomez; Dervins-Ravault, Delphine; Honoré, Nadine; Savchenko, Aleksey; Buchrieser, Carmen

    2014-01-01

    Summary Legionella pneumophila uses aquatic protozoa as replication niche and protection from harsh environments. Although L. pneumophila is not known to have a circadian clock, it encodes homologues of the KaiBC proteins of Cyanobacteria that regulate circadian gene expression. We show that L. pneumophila kaiB, kaiC and the downstream gene lpp1114, are transcribed as a unit under the control of the stress sigma factor RpoS. KaiC and KaiB of L. pneumophila do not interact as evidenced by yeast and bacterial two-hybrid analyses. Fusion of the C-terminal residues of cyanobacterial KaiB to Legionella KaiB restores their interaction. In contrast, KaiC of L. pneumophila conserved autophosphorylation activity, but KaiB does not trigger the dephosphorylation of KaiC like in Cyanobacteria. The crystal structure of L. pneumophila KaiB suggests that it is an oxidoreductase-like protein with a typical thioredoxin fold. Indeed, mutant analyses revealed that the kai operon-encoded proteins increase fitness of L. pneumophila in competitive environments, and confer higher resistance to oxidative and sodium stress. The phylogenetic analysis indicates that L. pneumophila KaiBC resemble Synechosystis KaiC2B2 and not circadian KaiB1C1. Thus, the L. pneumophila Kai proteins do not encode a circadian clock, but enhance stress resistance and adaption to changes in the environments. PMID:23957615

  5. Potential Climate Change Impacts on the Built Environment in the United States and Implications for Sustainability

    Science.gov (United States)

    Quattrochi, D.

    2012-12-01

    The built environment consists of components that have been made by humans at a range of scales from small (e.g., houses, shopping malls) to large (e.g., transportation networks) to highly modified landscapes such as cities. The impacts of climate change on the built environment, therefore, may have a multitude of effects on humans and the land. The impact of climate change may be exacerbated by the interaction of different events that singly may be minor, but together may have a synergistic set of impacts that are significant. Also, there may be feedback mechanisms wherein the built environment, particularly in the form of cities, may affect weather and the climate on local and regional scales. Besides having a host of such interactions, the impacts of climate change on urban areas will likely have thresholds, below which effects are incidental or of mild consequence, but beyond which the effects quickly become major. Hence, a city may be able to cope with prolonged heat waves, but if this is combined with severe drought, the overall result could be significant or even catastrophic, as accelerating demand for energy to cooling taxes water supplies needed both for energy supply and municipal water needs. Moreover, urban areas may be affected by changes in daily and seasonal high or low temperatures or precipitation, which may have a much more prolonged impact than the direct effect of these events. Thus, the cumulative impacts of multiple events may be more severe than those of any single event. Primary hazards include sea level rise and coastal storms, heat waves, intense precipitation, drought, extreme wind events, urban heat islands, and secondary air pollutants, and cold air events including frozen precipitation. Indicators need to be developed to provide a consistent, objective, and transparent overview of major variations in climate impacts, vulnerabilities, adaptation, and mitigation activities. Overall, indicators of climate change on the built environment

  6. Natural fumarolic alteration of fluorapatite, olivine, and basaltic glass, and implications for habitable environments on Mars.

    Science.gov (United States)

    Hausrath, Elisabeth M; Tschauner, Oliver

    2013-11-01

    Fumaroles represent a very important potential habitat on Mars because they contain water and nutrients. Global deposition of volcanic sulfate aerosols may also have been an important soil-forming process affecting large areas of Mars. Here we identify alteration from the Senator fumarole, northwest Nevada, USA, and in low-temperature environments near the fumarole to help interpret fumarolic and acid vapor alteration of rocks and soils on Mars. We analyzed soil samples and fluorapatite, olivine, and basaltic glass placed at and near the fumarole in in situ mineral alteration experiments designed to measure weathering under natural field conditions. Using synchrotron X-ray diffraction, we clearly observe hydroxyl-carbonate-bearing fluorapatite as a fumarolic alteration product of the original material, fluorapatite. The composition of apatites as well as secondary phosphates has been previously used to infer magmatic conditions as well as fumarolic conditions on Mars. To our knowledge, the observations reported here represent the first documented instance of formation of hydroxyl-carbonate-bearing apatite from fluorapatite in a field experiment. Retreat of olivine surfaces, as well as abundant NH4-containing minerals, was also characteristic of fumarolic alteration. In contrast, alteration in the nearby low-temperature environment resulted in formation of large pits on olivine surfaces, which were clearly distinguishable from the fumarolic alteration. Raman signatures of some fumarolically impacted surfaces are consistent with detection of the biological molecules chlorophyll and scytenomin, potentially useful biosignatures. Observations of altered minerals on Mars may therefore help identify the environment of formation and understand the aqueous history and potential habitability of that planet.

  7. Interface Design Implications for Recalling the Spatial Configuration of Virtual Auditory Environments

    Science.gov (United States)

    McMullen, Kyla A.

    Although the concept of virtual spatial audio has existed for almost twenty-five years, only in the past fifteen years has modern computing technology enabled the real-time processing needed to deliver high-precision spatial audio. Furthermore, the concept of virtually walking through an auditory environment did not exist. The applications of such an interface have numerous potential uses. Spatial audio has the potential to be used in various manners ranging from enhancing sounds delivered in virtual gaming worlds to conveying spatial locations in real-time emergency response systems. To incorporate this technology in real-world systems, various concerns should be addressed. First, to widely incorporate spatial audio into real-world systems, head-related transfer functions (HRTFs) must be inexpensively created for each user. The present study further investigated an HRTF subjective selection procedure previously developed within our research group. Users discriminated auditory cues to subjectively select their preferred HRTF from a publicly available database. Next, the issue of training to find virtual sources was addressed. Listeners participated in a localization training experiment using their selected HRTFs. The training procedure was created from the characterization of successful search strategies in prior auditory search experiments. Search accuracy significantly improved after listeners performed the training procedure. Next, in the investigation of auditory spatial memory, listeners completed three search and recall tasks with differing recall methods. Recall accuracy significantly decreased in tasks that required the storage of sound source configurations in memory. To assess the impacts of practical scenarios, the present work assessed the performance effects of: signal uncertainty, visual augmentation, and different attenuation modeling. Fortunately, source uncertainty did not affect listeners' ability to recall or identify sound sources. The present

  8. Seawater-sediment interaction at elevated temperatures and pressures: implications for the near field chemical environment

    International Nuclear Information System (INIS)

    Seyfried, W.E. Jr.; Thornton, E.C.; Janecky, D.R.

    1981-01-01

    Results of four experiments are reported which document chemical exchange and mineralogic modification during seawater-sediment interaction at 200 0 to 300 0 C, 500 bars. Sediments used for this study are from MPG-1 (central North Pacific). Experimental conditions (T, P, W/R) were chosen to be reasonably analogous to conditions which will characterize the near field environment; that is a zone within approximately 1 m of the buried waste canister. In general, the major element chemistry of seawater was similarly modified in all experiments. The aqueous concentrations of Ca, Mg, Sr, and SO 4 decreased and SiO 2 /sub (aq)/, Na, K, and ΣCO 2 increased relative to values in seawater prior to reaction with sediments. pH decreased and remained distinctly acid. Con comitantly significant concentrations of heavy metals entered seawater from the sediments during reaction. Dissolution of Mn-rich phases profoundly affected alteration processes. For example, reaction of MnO 2 components of the smectite-rich sediment (Pacific smectite) with seawater created an unusually oxidizing milieu (fO 2 = 10 -7 74 ), and resulted in dissolution of significant quantities of Au from the reaction cell. Although illite-quartz-Fe-chlorite (sediment B)-seawater interaction also created a relatively oxidizing environment, this environment was not capable of oxidizing Au. Thus, in this regard (oxidation potential) sediment mineralogy exerts a strong influence. Mineralogic modification of sediment B at 200 0 and 300 0 C was minor and characterized by partial dissolution of illite and exchange of Fe for Mg in chlorite. In contrast the smectite-rich sediment, which, prior to reaction with seawater contained a poorly crystalline smectite phase, clinoptilolite, and amorphous material, recrystallized totally to a well defined smectite mineral. Anhydrite was abundantly present amongst the alteration products of all experiments

  9. Distribution and speciation of radionuclides in the environment: their implication in radioecology

    International Nuclear Information System (INIS)

    Cigna, A.A.

    2000-01-01

    Following the discovery of X-ray and radioactivity, radioecological researches were initiated all over the world. But only after the 2nd World War the knowledge of the effects of ionizing radiations on the organisms and the processes of the diffusion of radionuclides in the environment achieved an outstanding level. On account of the great sensitivity of the radioactivity measurements, negligible amounts of radionuclides could be easily identified and measured in different environmental compartments without any slight interference with the metabolisms of living organisms. Many processes and phenomena could then be detected and studied. Ecology took advantage from such studies and its growth in a few years was probably greater than in the whole of the previous century. As a result a great interest in the determination of concentration factors in any organism spread widely in many laboratories, a large number of values were available in a few years time. Further it appeared that the transfer of the radionuclides from the environment to man could be better evaluated and monitored through the definition of some 'critical' quantity: a critical group, a critical radionuclide, a critical pathway, etc. The fallout dispersed by the experimental detonation of nuclear weapons and, more recently, the contamination due to the Chernobyl accident, were the most important sources of radionuclides in most of the environmental compartments. Undoubtedly in the post Chernobyl situation radioecology is in a better position because the description of the environment is presently much closer to reality and its conclusions much more reliable. But, as it is usual in science development, new problems appeared and new questions were asked. Speciation of radionuclides and other pollutants is considered and some of the effects on the diffusion and consequences are discussed. Finally, the application of the great amount of knowledge obtained by the radioecological research to a better

  10. Airborne contamination in the indoor environment and its implications for dose

    International Nuclear Information System (INIS)

    Andersson, K.G.; Roed, J.; Byrne, M.A.; Hession, H.; Clark, P.; Elahi, E.; Buskov, A.; Hou, X.L.; Prip, H.; Olsen, S.K.; Roed, T.

    2004-04-01

    Previous work has indicated that radiation doses from deposition on human skin, hair and clothing may contribute significantly to the dose received after a major nuclear accident, such as that, which happened at Chernobyl in 1986. The available data was, however, sparse and associated with considerable variation, clearly showing a need for further investigations to verify preliminary conclusions, examine processes in greater detail and identify important factors causing the observed parameter variation. For instance, the impacts of thermophoresis, electrophoresis, skin moisture and wind speed on the deposition of contaminant aerosol were examined, and since the previous measurements had indicated that elemental iodine could be a particularly problematic contaminant, experimental work was additionally undertaken to examine the process of deposition of this species to skin. Since both clearance and percutaneous penetration of deposited contaminants could play important roles in determining doses, experimental programmes were dedicated to the identification of parameters of interest in these contexts. Also doses from contamination on different surfaces in the indoor environment have in the past traditionally been neglected, and a theoretical approach, based on measurements, was developed for accurate prediction of these doses under different conditions. Also resuspension of deposited matter and its role in dose formation, by subsequent deposition or inhalation, was investigated through experiments. Contact transfer of contaminants from an indoor surface to human skin may give yet another contribution to dose and also the relevant parameters in this direction were examined experimentally. The ultimate goal of the investigations was to enable the determination of the various contributions to dose in a contaminated indoor environment. A model methodology was developed and an example of its use was given. It was found that after a major nuclear accident, doses from indoor

  11. Gene-environment interactions in early life and adulthood: implications for cocaine intake

    OpenAIRE

    Veen, Rixt van der

    2008-01-01

    The objective of the research described in this thesis was to demonstrate the role of gene-environment interactions in the emergence of individual differences in cocaine use. For this purpose we used two inbred mouse strains, the C57Bl/6 (C57) and DBA/2 (DBA), which are known to differ in drug-intake and to be differentially sensitive to several stressors. We studied the impact of early life experiences (long-term influence) as well as a later life psychosocial stressor (short-term influence)...

  12. Community food environment measures in the Alabama Black Belt: Implications for cancer risk reduction

    Science.gov (United States)

    Gyawu, Rebecca; Quansah, Joseph E.; Fall, Souleymane; Gichuhi, Peter N.; Bovell-Benjamin, Adelia C.

    2015-01-01

    In-store measures were utilized to evaluate the availability of healthy food choices and nutrition/health promotion messages for cancer risk reduction in the selected Alabama Black Belt counties/cities. Sixty one retail food outlets (RFOs) were audited in 12 Alabama Black Belt cities. Store types included convenience stores (49.2%), restaurants (19.7%), fast food restaurants (16.4%), small supermarkets (8.2%), and large supermarket and farmers' markets (3.3 %), respectively. Although there were low numbers of farmers' markets/street stands and large supermarkets, these had significantly (p food environment had limited opportunities for healthy food choices. PMID:26844138

  13. Engaging diverse student audiences in contemporary blended learning environments in Australian higher business education: Implications for Design and Practice

    Directory of Open Access Journals (Sweden)

    Graeme Pye

    2015-11-01

    Full Text Available This research reports on a student audience engaging in an Australian university’s undergraduate commerce program core unit that is offered across three separate geographic campus locations and online. The research extends upon work undertaken on student engagement in online settings and lies in the domain of blended learning design and practice in the Australian higher education business context. Findings, inter alia, are presented across six major student engagement dimensions as applied to the interplay between online and located/campus learning (i.e. Online Active Learning, Online Social Interaction, Online Collaboration, Online Teaching, Online Assessment, and Online Contact with Staff. Implications for blended learning design, eLearning and practice in such complex environments are examined.

  14. FISCAL AND ACCOUNTING ISSUES CONCERNING THE FLAT-RATE TAX AND ITS IMPLICATIONS ON THE BUSINESS ENVIRONMENT IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Lucia PALIU-POPA

    2010-06-01

    Full Text Available The introduction of flat-rate tax for companies is a novelty in the Romanian tax system, which is why businessmen' reactions were different, most of them criticizing harshly the opportunity for such a measure, arguing that during this crisis period for Romania, it may lead to the bankruptcy of tens of thousands of firms, consequently to an increase of the number of unemployed with several hundred thousands. Although the flat tax for natural persons has been applied for several decades, no legislation which has regulated this type of tax has given a definition of the flat-rate tax. Based on these considerations, in this paper we intend to address the theoretical and practical issues concerning the flat tax, in fiscal and accounting terms, together with its implications on the Romanian business environment.

  15. Student Blogging: Implications for Learning in a Virtual Text-Based Environment

    Science.gov (United States)

    Deed, Craig; Edwards, Anthony

    Realising the potential for web-based communication in learning and teaching is challenging for educators. The purpose of this paper is to report students' attitudes and perception of active learning when using an unrestricted blog in an academic context. It will examine if an unrestricted blog can be used to support reflective and critical discussion leading to the construction of knowledge whether. Unrestricted in this context refers to autonomous individual and group activity undertaken in an unstructured online environment. It will attempt provide an insight into what students make of working at the intersection between academic and online environments. Data was collected using an online survey with questions focused on student perceptions of the type, frequency and effectiveness of their strategy use. Analysis of the resulting material was conducted using Bloom's revised taxonomy to determine whether student strategy was useful in supporting the construction of knowledge. Our research indicates that students need to suitably prepare themselves or be prepared by others to make the most effective use of their prior familiarity with this form of communication technology (which is usually informal) in order to constructing knowledge in an academic context. Thus we conclude that effective learning will only emerge from considered pedagogical design, informed by the student experience and perspective.

  16. Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars

    Science.gov (United States)

    Mickol, R. L.; Kral, T. A.

    2017-12-01

    The low pressure at the surface of Mars (average: 6 mbar) is one potentially biocidal factor that any extant life on the planet would need to endure. Near subsurface life, while shielded from ultraviolet radiation, would also be exposed to this low pressure environment, as the atmospheric gas-phase pressure increases very gradually with depth. Few studies have focused on low pressure as inhibitory to the growth or survival of organisms. However, recent work has uncovered a potential constraint to bacterial growth below 25 mbar. The study reported here tested the survivability of four methanogen species ( Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis) under low pressure conditions approaching average martian surface pressure (6 mbar - 143 mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3 days - 21 days) at pressures down to 6 mbar. This research is an important stepping-stone to determining if methanogens can actively metabolize/grow under these low pressures. Additionally, the recently discovered recurring slope lineae suggest that liquid water columns may connect the surface to deeper levels in the subsurface. If that is the case, any organism being transported in the water column would encounter the changing pressures during the transport.

  17. Photolytic degradation of methyl-parathion and fenitrothion in ice and water: Implications for cold environments

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jan [Lancaster Environment Centre, Centre for Chemicals Management, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Kurkova, Romana; Klanova, Jana [RECETOX, Faculty of Science, Masaryk University, Kamenice 3, 625 00 Brno (Czech Republic); Klan, Petr, E-mail: klan@sci.muni.c [Dept of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A8, 625 00 Brno (Czech Republic); Halsall, Crispin J., E-mail: c.halsall@lancaster.ac.u [Lancaster Environment Centre, Centre for Chemicals Management, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2009-12-15

    Here we investigate the photodegradation of structurally similar organophosphorus pesticides; methyl-parathion and fenitrothion in water (20 deg. C) and ice (-15 deg. C) under environmentally-relevant conditions with the aim of comparing these laboratory findings to limited field observations. Both compounds were found to be photolyzed more efficiently in ice than in aqueous solutions, with quantum yields of degradation being higher in ice than in water (fenitrothion > methyl-parathion). This rather surprising observation was attributed to the concentration effect caused by freezing the aqueous solutions. The major phototransformation products included the corresponding oxons (methyl-paraoxon and fenitroxon) and the nitrophenols (3-methyl-nitrophenol and nitrophenol) in both irradiated water and ice samples. The presence of oxons in ice following irradiation, demonstrates an additional formation mechanism of these toxicologically relevant compounds in cold environments, although further photodegradation of oxons in ice indicates that photochemistry of OPs might be an environmentally important sink in cold environments. - Photodegradation of methyl-parathion and fenitrothion in water and ice under environmentally-relevant conditions is described.

  18. Parental influence on children's early eating environments and obesity risk: implications for prevention.

    Science.gov (United States)

    Anzman, S L; Rollins, B Y; Birch, L L

    2010-07-01

    Most childhood obesity prevention efforts have focused on school-age children and adolescents and have had limited success. We argue that the first years of life, including the prenatal period, the postnatal suckling period and the transition to the modified adult diet, may provide opportunities for preventive interventions. These early periods are characterized by high plasticity and rapid transitions, and parents have a high degree of control over children's environments and experiences. Observational and experimental evidence reveal persistent effects of early environments on eating behavior and obesity risk, suggesting that interventions should be tested during these early periods. The central task parents have in early development points to their potential as key targets and agents of change in early preventive interventions. In this paper, we review evidence of early environmental effects on children's eating and obesity risk, highlighting ways that parental feeding practices and parents' own behaviors impact these outcomes and calling for further experimental research to elucidate whether these factors are indeed promising targets for childhood obesity preventive interventions.

  19. VECTORS of change in the marine environment: Ecosystem and economic impacts and management implications

    Science.gov (United States)

    Austen, M. C.; Crowe, T. P.; Elliott, M.; Paterson, D. M.; Peck, M. A.; Piraino, S.

    2018-02-01

    Human use of the European marine environment is increasing and diversifying. This is creating new mechanisms for human induced-changes in marine life which need to be understood and quantified as well as the impact of these changes on ecosystems, their structures (e.g. biodiversity) and functioning (e.g. productivity), and the social and economic consequences that arise. The current and emerging pressures are multiple and interacting, arising, for example, from transport, platforms for renewable and non-renewable energy, exploitation of living and non-living resources, agricultural and industrial discharges, together with wider environmental changes (including climate change). Anticipating the future consequences of these pressures and vectors of change for marine life and of adaptation and mitigation measures (such as the introduction of new technologies and structures, new ballast water practices, ocean and offshore wind energy devices and new fishing strategies) is a prerequisite to the development and implementation of strategies, policies and regulations to manage the marine environment, such as the IMO Convention on ballast water management and the EU Maritime Policy and Marine Strategy Framework Directive.

  20. Placental adaptations to the maternal-fetal environment: implications for fetal growth and developmental programming.

    Science.gov (United States)

    Sandovici, Ionel; Hoelle, Katharina; Angiolini, Emily; Constância, Miguel

    2012-07-01

    The placenta is a transient organ found in eutherian mammals that evolved primarily to provide nutrients for the developing fetus. The placenta exchanges a wide array of nutrients, endocrine signals, cytokines and growth factors with the mother and the fetus, thereby regulating intrauterine development. Recent studies show that the placenta is not just a passive organ mediating maternal-fetal exchange. It can adapt its capacity to supply nutrients in response to intrinsic and extrinsic variations in the maternal-fetal environment. These dynamic adaptations are thought to occur to maximize fetal growth and viability at birth in the prevailing conditions in utero. However, some of these adaptations may also affect the development of individual fetal tissues, with patho-physiological consequences long after birth. Here, this review summarizes current knowledge on the causes, possible mechanisms and consequences of placental adaptive responses, with a focus on the regulation of transporter-mediated processes for nutrients. This review also highlights the emerging roles that imprinted genes and epigenetic mechanisms of gene regulation may play in placental adaptations to the maternal-fetal environment. Copyright © 2012 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  1. Olivine Dissolution in Seawater: Implications for CO2 Sequestration through Enhanced Weathering in Coastal Environments

    Science.gov (United States)

    2017-01-01

    Enhanced weathering of (ultra)basic silicate rocks such as olivine-rich dunite has been proposed as a large-scale climate engineering approach. When implemented in coastal environments, olivine weathering is expected to increase seawater alkalinity, thus resulting in additional CO2 uptake from the atmosphere. However, the mechanisms of marine olivine weathering and its effect on seawater–carbonate chemistry remain poorly understood. Here, we present results from batch reaction experiments, in which forsteritic olivine was subjected to rotational agitation in different seawater media for periods of days to months. Olivine dissolution caused a significant increase in alkalinity of the seawater with a consequent DIC increase due to CO2 invasion, thus confirming viability of the basic concept of enhanced silicate weathering. However, our experiments also identified several important challenges with respect to the detailed quantification of the CO2 sequestration efficiency under field conditions, which include nonstoichiometric dissolution, potential pore water saturation in the seabed, and the potential occurrence of secondary reactions. Before enhanced weathering of olivine in coastal environments can be considered an option for realizing negative CO2 emissions for climate mitigation purposes, these aspects need further experimental assessment. PMID:28281750

  2. Effects of correlations and fees in random multiplicative environments: Implications for portfolio management

    Science.gov (United States)

    Alper, Ofer; Somekh-Baruch, Anelia; Pirvandy, Oz; Schaps, Malka; Yaari, Gur

    2017-08-01

    Geometric Brownian motion (GBM) is frequently used to model price dynamics of financial assets, and a weighted average of multiple GBMs is commonly used to model a financial portfolio. Diversified portfolios can lead to an increased exponential growth compared to a single asset by effectively reducing the effective noise. The sum of GBM processes is no longer a log-normal process and has a complex statistical properties. The nonergodicity of the weighted average process results in constant degradation of the exponential growth from the ensemble average toward the time average. One way to stay closer to the ensemble average is to maintain a balanced portfolio: keep the relative weights of the different assets constant over time. To keep these proportions constant, whenever assets values change, it is necessary to rebalance their relative weights, exposing this strategy to fees (transaction costs). Two strategies that were suggested in the past for cases that involve fees are rebalance the portfolio periodically and rebalance it in a partial way. In this paper, we study these two strategies in the presence of correlations and fees. We show that using periodic and partial rebalance strategies, it is possible to maintain a steady exponential growth while minimizing the losses due to fees. We also demonstrate how these redistribution strategies perform in a phenomenal way on real-world market data, despite the fact that not all assumptions of the model hold in these real-world systems. Our results have important implications for stochastic dynamics in general and to portfolio management in particular, as we show that there is a superior alternative to the common buy-and-hold strategy, even in the presence of correlations and fees.

  3. Detection and Antimicrobial Resistance of Vibrio Isolates in Aquaculture Environments: Implications for Public Health.

    Science.gov (United States)

    Igbinosa, Etinosa O

    2016-04-01

    The aim of this study was to evaluate the presence of Vibrio isolates recovered from four different fish pond facilities in Benin City, Nigeria, determine their antibiogram profiles, and evaluate the public health implications of these findings. Fish pond water samples were collected from four sampling sites between March and September 2014. A total of 56 samples were collected and screened for the isolation of Vibrio species using standard culture-based methods. Polymerase chain reaction (PCR) was used to confirm the identities of the Vibrio species using the genus-specific and species-specific primers. Vibrio species were detected at all the study sites at a concentration on the order of 10(3) and 10(6) CFU/100 ml. A total of 550 presumptive Vibrio isolates were subjected to PCR confirmation. Of these isolates, 334 isolates tested positive, giving an overall Vibrio prevalence rate of 60.7%. The speciation of the 334 Vibrio isolates from fish ponds yielded 32.63% Vibrio fluvialis, 20.65% Vibrio parahaemolyticus, 18.26% Vibrio vulnificus, and 28.44% other Vibrio species. In all, 167 confirmed Vibrio isolates were selected from a pool of 334 confirmed Vibrio isolates for antibiogram profiling. The susceptibility profiles of 20 antimicrobial agents on the isolates revealed a high level of resistance for AMP(R), ERY(R), NAL(R), SUL(R), TMP(R), SXT(R), TET(R), OTC(R), and CHL(R). The percentage of multiple drug resistance Vibrio isolates was 67.6%. The multiple antibiotic resistance index mean value of 0.365 for the Vibrio isolates found in this study indicated that the Vibrio isolates were exposed to high-risk sources of contamination when antibiotics were frequently used. The resistant Vibrio strains could be transmitted through the food chain to humans and therefore constitutes a risk to public health.

  4. Implications of transportation policies on energy and environment in Kathmandu Valley, Nepal

    International Nuclear Information System (INIS)

    Dhakal, Shobhakar

    2003-01-01

    This paper estimates and analyzes the historical and future trends of energy demand and environmental emissions from passenger transportation of the Kathmandu Valley covering CO 2 , CO, HC, NO x , SO 2 , total suspended particles (TSP) and lead (Pb). It uses the Long-range Energy Alternatives Planning System framework for constructing future scenarios up to year 2020 and analyzing their implications; these scenarios mainly deal with the traffic improvement measures, promotion of public transportation and electric vehicles. The results estimate over a four-fold increase in energy demand in 1988-2000. TSP increase of 4.5 times in this period is the major concern since high particulate concentration is already above World Health Organization guidelines. Under the non-intervention scenario, energy demand in 2020 is estimated to be 2.7 times that in the year 2000. Similarly, 2.5 times increase of TSP in 2020 from the year 2000 is estimated that would further increase the TSP concentrations. The scenario analyses suggest that increasing vehicle speed, promoting public transportation and promoting electric vehicles could reduce energy demand by 28%, 28% and 18%, respectively, while promoting a reasonably comfortable condition on overcrowded public transportation could increase energy demand by 10% from non-intervention scenario. For TSP, any future measures would not be enough unless the attention is not paid to in-use vehicle stock. A mix of all the policies mentioned above has potentials to cut down CO 2 emissions to over 60% from the non-intervention case in 2020

  5. Chemical implications for the presence of introduced materials in the post-emplacement environment

    International Nuclear Information System (INIS)

    Meike, A.

    1993-11-01

    This paper addresses our ability to predict the chemical consequences of the presence of introduced materials, many of them man-made, in a radioactive waste repository. The chemical modeling ability required to describe this environment over a 10,000 year period is unique and unprecedented. It requires knowledge of parameters that have never been measured, many of them with respect to introduced materials. This paper discusses considerations that are required to establish the potential significance of introduced materials, especially those that could compromise the lifetime of the waste packages or affect the transport of radionuclides from breached containers. The paper presents issues related to the stability of individual compounds, the potential alteration of predicted natural chemical reactions, the potential moderation of those effects by natural zeolites, and the potential for interactions at elevated temperatures between rock, water, water vapor, radiation, waste package, and introduced materials

  6. The Electrostatic Environments of the Moon and Mars: Implications for Human Missions

    Science.gov (United States)

    Calle, Carlos I.; Mackey, Paul J.; Johansen, Michael R.; Hogue, Michael D.; Phillips, James; Cox, Rachel E.

    2016-01-01

    Lacking a substantial atmosphere, the moon is exposed to the full spectrum of solar radiation as well as to cosmic rays. Electrostatically, the moon is a charged body in a plasma. A Debye sheet meters high on the dayside of the moon and kilometers high on the night side envelops the moon. This sheet isolates the lunar surface from high energy particles coming from the sun. The electrostatic environment on Mars is controlled by its ever present atmospheric dust. Dust devils and dust storms tribocharge this dust. Theoretical studies predict that lightning and/or glow discharges should be present on Mars, but none have been directly observed. Experiments are planned to shed light on this issue.

  7. Microbial Fossils from Terrestrial Subsurface Hydrothermal Environments: Examples and Implications for Mars

    Science.gov (United States)

    Hofmann, Beda A.; Farmer, Jack; Chang, Sherwood (Technical Monitor)

    1997-01-01

    The recognition of biological signatures in ancient epithermal deposits has special relevance for studies of early blaspheme evolution and in exploring for past life on Mars. Recently, proposals for the existence of an extensive subsurface blaspheme on Earth, dominated by chemoautotrophic microbial life, has gained prominence. However, reports of fossilized microbial remains, or biosedimentary structures (e.g. stromatolites) from the deposits of ancient subsurface systems, are rare. Microbial preservation is favoured where high population densities co-exist with rapid mineral precipitation. Near-surface epithetical systems with strong gradients in temperature and redox are good candidates for the abundant growth and fossilization of microorganisms, and are also favorable environments for the precipitation of ore minerals. Therefore, we might expect microbial remain, to be particularly well preserved in various kinds of hydrothermal and diagenetic mineral precipitates that formed below the upper temperature limit for life (approx. 120 C).

  8. Community food environment measures in the Alabama Black Belt: Implications for cancer risk reduction

    Directory of Open Access Journals (Sweden)

    Rebecca Gyawu

    2015-01-01

    Full Text Available In-store measures were utilized to evaluate the availability of healthy food choices and nutrition/health promotion messages for cancer risk reduction in the selected Alabama Black Belt counties/cities. Sixty one retail food outlets (RFOs were audited in 12 Alabama Black Belt cities. Store types included convenience stores (49.2%, restaurants (19.7%, fast food restaurants (16.4%, small supermarkets (8.2%, and large supermarket and farmers' markets (3.3 %, respectively. Although there were low numbers of farmers' markets/street stands and large supermarkets, these had significantly (p < 0.0001 higher health scores than the other store types. A few health promotion messages were highly visible or obscurely positioned in some RFOs. The Alabama Black Belt food environment had limited opportunities for healthy food choices.

  9. Experimental studies of free defect generation during irradiation: Implications for reactor environments

    International Nuclear Information System (INIS)

    Rehn, L.E.; Birtcher, R.C.

    1993-01-01

    Over the past several years, systematic experiments have revealed that irradiations which generate energetically dense cascades are much less effective than light-ion, MeV electron, or thermal neutron irradiations at producing freely-migrating defects. In this paper, the systematic results on freely-migrating defect production from ion irradiation studies are briefly summarized. Difficulties with applying a simple extrapolation of the ion-irradiation results to neutron environments are discussed. This discussion, coupled with our existing knowledge of neutron-induced property changes, indicates that Compton scattering, and the (n,γ), (n,He) and (n,p) nuclear reactions, are considerably more important for producing freely-migrating defects than was previously realized

  10. Use of mercury in the small mining and the implications for the environment and the health

    International Nuclear Information System (INIS)

    Hennig, Walther

    2004-01-01

    In the auriferous small and handmade mining, the use of mercury for the amalgamation of minerals and concentrated auriferous it is universally extended. This is attributed to the supposedly easy handling that doesn't require of special technical knowledge, at the relatively low cost of the mercury with relationship to the mineral value and the readiness of included mercury in the most remote regions. Of those more than 3.000 annual t of mercury that arrive of the most diverse sources (E.g. 1.500 t of central thermal of coal and incinerator plants of garbage) to the environment, single 500 t approximately corresponds the auriferous mining, but in form of high local concentrations. Exams carried out in 72 companies of gold mining and silver they checked in around 15% of the employees an excessive exhibition of mercury, in some cases with values 50 times that the allowed. The main roads for which the mercury used in the gold extraction, arrives to the environment, are relicts of mineral preparation and mercury vapors that arise in the distillation open of amalgam without retort. The consumption of mercury, that is to say the losses to the environment, depending on the mineral type and of the applied preparation methods, they reach of some little grams for ton of mineral treaty up to 2 kg Hg / mineral t. Be which is the way for which the mercury arrives to the environment, it is absorbed by the plants and animals and it is integrated in the foods chain. Animals that are at the end of the foods chain, for E j fish, demonstrate the highest concentrations. The mercury possesses a high neurotoxic potential, it concentrates on the neurons and it blocks the transport of signs there and nutritious. Polluted people with mercury assimilate with more easiness another toxic environmental matter, since the mercury impedes to the cell of defending in front of her, allowing this way that heavy metals, pesticides and formaldehydes penetrate the cell. In their vaporous physical state

  11. Quartz OSL Dating of the loess deposit in the eastern Tibetan Plateau and its environment implications since the Last Glaciation

    Science.gov (United States)

    Yang, S.; Cheng, T.; Liu, W.; Fang, X.

    2017-12-01

    Loess deposit is widespread in the Chuanxi Plateau, the eastern Tibetan Plateau, which is a critical archive for understanding the aeolian process, the evolution of the westerly and the environment changes on the Plateau. Previous studies have shown its aeolian origin, and mainly transported by wind from the western part of the Tibetan Plateau. However, the aeolian processes of the loess and its environment implications are not well understood mainly due to lack of detailed age controls. We carry out a combined quartz optically stimulated luminescence (OSL) dating and accelerator mass spectrometry radiocarbon dating (AMS 14-C) for the loess deposits in Garzê and Jinchuan. The results indicate that the quartz OSL dating can provide reliable age controls for the loess-paleosol sequences from the Chuanxi Plateau, showing the potential of OSL to date loess in the high altitude region. The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field. The constructed OSL and AMS 14-C chronology of the Garzê loess reveals that the widespread loess in Ganzi Region deposited since the Last Glacial. The dust accumulation is rapid during marine isotope stage (MIS) 3 and 2, and a relative low accumulation rate in the Holocene, which may related with the desertification processes of the inner Tibetan Plateau.

  12. Fate of Chloromethanes in the Atmospheric Environment: Implications for Human Health, Ozone Formation and Depletion, and Global Warming Impacts

    Science.gov (United States)

    Tsai, Wen-Tien

    2017-01-01

    Among the halogenated hydrocarbons, chloromethanes (i.e., methyl chloride, CH3Cl; methylene chloride, CH2Cl2; chloroform, CHCl3; and carbon tetrachloride, CCl4) play a vital role due to their extensive uses as solvents and chemical intermediates. This article aims to review their main chemical/physical properties and commercial/industrial uses, as well as the environment and health hazards posed by them and their toxic decomposition products. The environmental properties (including atmospheric lifetime, radiative efficiency, ozone depletion potential, global warming potential, photochemical ozone creation potential, and surface mixing ratio) of these chlorinated methanes are also reviewed. In addition, this paper further discusses their atmospheric fates and human health implications because they are apt to reside in the lower atmosphere when released into the environment. According to the atmospheric degradation mechanism, their toxic degradation products in the troposphere include hydrogen chloride (HCl), carbon monoxide (CO), chlorine (Cl2), formyl chloride (HCOCl), carbonyl chloride (COCl2), and hydrogen peroxide (H2O2). Among them, COCl2 (also called phosgene) is a powerful irritating gas, which is easily hydrolyzed or thermally decomposed to form hydrogen chloride. PMID:29051455

  13. Fate of Chloromethanes in the Atmospheric Environment: Implications for Human Health, Ozone Formation and Depletion, and Global Warming Impacts.

    Science.gov (United States)

    Tsai, Wen-Tien

    2017-09-21

    Among the halogenated hydrocarbons, chloromethanes (i.e., methyl chloride, CH₃Cl; methylene chloride, CH₂Cl₂; chloroform, CHCl₃; and carbon tetrachloride, CCl₄) play a vital role due to their extensive uses as solvents and chemical intermediates. This article aims to review their main chemical/physical properties and commercial/industrial uses, as well as the environment and health hazards posed by them and their toxic decomposition products. The environmental properties (including atmospheric lifetime, radiative efficiency, ozone depletion potential, global warming potential, photochemical ozone creation potential, and surface mixing ratio) of these chlorinated methanes are also reviewed. In addition, this paper further discusses their atmospheric fates and human health implications because they are apt to reside in the lower atmosphere when released into the environment. According to the atmospheric degradation mechanism, their toxic degradation products in the troposphere include hydrogen chloride (HCl), carbon monoxide (CO), chlorine (Cl₂), formyl chloride (HCOCl), carbonyl chloride (COCl₂), and hydrogen peroxide (H₂O₂). Among them, COCl₂ (also called phosgene) is a powerful irritating gas, which is easily hydrolyzed or thermally decomposed to form hydrogen chloride.

  14. Engineered metal based nanomaterials in aqueous environments: Interactions, transformations and implications

    Science.gov (United States)

    Mudunkotuwa, Imali Ama

    Nanoscience and nanotechnology offer potential routes towards addressing critical issues such as clean and sustainable energy, environmental protection and human health. Specifically, metal and metal oxide nanomaterials are found in a wide range of applications and therefore hold a greater potential of possible release into the environment or for the human to be exposed. Understanding the aqueous phase behavior of metal and metal oxide nanomaterials is a key factor in the safe design of these materials because their interactions with living systems are always mediated through the aqueous phase. Broadly the transformations in the aqueous phase can be classified as dissolution, aggregation and adsorption which are dependent and linked processes to one another. The complexity of these processes at the liquid-solid interface has therefore been one of the grand challenges that has persisted since the beginning of nanotechnology. Although classical models provide guidance for understanding dissolution and aggregation of nanoparticles in water, there are many uncertainties associated with the recent findings. This is often due to a lack of fundamental knowledge of the surface structure and surface energetics for very small particles. Therefore currently the environmental health and safety studies related to nanomaterials are more focused on understanding the surface chemistry that governs the overall processes in the liquid-solid interfacial region at the molecular level. The metal based nanomaterials focused on in this dissertation include TiO2, ZnO, Cu and CuO. These are among the most heavily used in a number of applications ranging from uses in the construction industry to cosmetic formulation. Therefore they are produced in large scale and have been detected in the environment. There is debate within the scientific community related to their safety as a result of the lack of understanding on the surface interactions that arise from the detailed nature of the surfaces

  15. Salinity tolerances and use of saline environments by freshwater turtles: implications of sea level rise.

    Science.gov (United States)

    Agha, Mickey; Ennen, Joshua R; Bower, Deborah S; Nowakowski, A Justin; Sweat, Sarah C; Todd, Brian D

    2018-03-25

    The projected rise in global mean sea levels places many freshwater turtle species at risk of saltwater intrusion into freshwater habitats. Freshwater turtles are disproportionately more threatened than other taxa; thus, understanding the role of salinity in determining their contemporary distribution and evolution should be a research priority. Freshwater turtles are a slowly evolving lineage; however, they can adapt physiologically or behaviourally to various levels of salinity and, therefore, temporarily occur in marine or brackish environments. Here, we provide the first comprehensive global review on freshwater turtle use and tolerance of brackish water ecosystems. We link together current knowledge of geographic occurrence, salinity tolerance, phylogenetic relationships, and physiological and behavioural mechanisms to generate a baseline understanding of the response of freshwater turtles to changing saline environments. We also review the potential origins of salinity tolerance in freshwater turtles. Finally, we integrate 2100 sea level rise (SLR) projections, species distribution maps, literature gathered on brackish water use, and a phylogeny to predict the exposure of freshwater turtles to projected SLR globally. From our synthesis of published literature and available data, we build a framework for spatial and phylogenetic conservation prioritization of coastal freshwater turtles. Based on our literature review, 70 species (∼30% of coastal freshwater turtle species) from 10 of the 11 freshwater turtle families have been reported in brackish water ecosystems. Most anecdotal records, observations, and descriptions do not imply long-term salinity tolerance among freshwater turtles. Rather, experiments show that some species exhibit potential for adaptation and plasticity in physiological, behavioural, and life-history traits that enable them to endure varying periods (e.g. days or months) and levels of saltwater exposure. Species that specialize on

  16. Gene x environment interactions in conduct disorder: Implications for future treatments.

    Science.gov (United States)

    Holz, Nathalie E; Zohsel, Katrin; Laucht, Manfred; Banaschewski, Tobias; Hohmann, Sarah; Brandeis, Daniel

    2016-08-18

    Conduct disorder (CD) causes high financial and social costs, not only in affected families but across society, with only moderately effective treatments so far. There is consensus that CD is likely caused by the convergence of many different factors, including genetic and adverse environmental factors. There is ample evidence of gene-environment interactions in the etiology of CD on a behavioral level regarding genetically sensitive designs and candidate gene-driven approaches, most prominently and consistently represented by MAOA. However, conclusive indications of causal GxE patterns are largely lacking. Inconsistent findings, lack of replication and methodological limitations remain a major challenge. Likewise, research addressing the identification of affected brain pathways which reflect plausible biological mechanisms underlying GxE is still very sparse. Future research will have to take multilevel approaches into account, which combine genetic, environmental, epigenetic, personality, neural and hormone perspectives. A better understanding of relevant GxE patterns in the etiology of CD might enable researchers to design customized treatment options (e.g. biofeedback interventions) for specific subgroups of patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Implications of one-year basalt weathering/reactivity study for a basalt repository environment

    International Nuclear Information System (INIS)

    Pine, G.L.; Jantzen, C.M.

    1987-03-01

    The Savannah River Laboratory is testing the performance of the Defense Waste Processing Facility glass under conditions representing potential repository environments. For a basalt repository, one of the important issues is how rapidly reducing conditions are re-established after placement of the waste. The objective of this study was to examine the factors affecting the reactivity of the basalt. Construction of a nuclear waste repository in basalt will temporarily perturb the groundwater conditions, creating more oxidizing (air-saturated) conditions than an undisturbed repository system. Reducing conditions can be beneficial to the performance of waste glass and canisters, and may limit the transport of certain radionuclides. The Basalt Waste Isolation Project intends to use a backfill containing crushed basalt to re-establish the reducing conditions of the groundwater. The reactivity of the basalt has been found to be minimal once the fresh crushed surfaces have been weathered and the reactive intergranular glass component has been leached, e.g., by long-term surface storage. Crushing of the basalt for pneumatic emplacement of the backfill should, therefore, occur shortly before placement in the repository. This backfill must contain a minimum of 5 percent reactive fines (<100 mesh), to rapidly achieve reducing conditions. 23 refs., 21 figs., 18 tabs

  18. The Urban Heat Island: Implications for Health in a Changing Environment.

    Science.gov (United States)

    Heaviside, Clare; Macintyre, Helen; Vardoulakis, Sotiris

    2017-09-01

    The Urban Heat Island (UHI) is a well-studied phenomenon, whereby urban areas are generally warmer than surrounding suburban and rural areas. The most direct effect on health from the UHI is due to heat risk, which is exacerbated in urban areas, particularly during heat waves. However, there may be health benefits from warming during colder months. This review highlights recent attempts to quantitatively estimate the health impacts of the UHI and estimations of the health benefits of UHI mitigation measures. Climate change, increasing urbanisation and an ageing population in much of the world, is likely to increase the risks to health from the UHI, particularly from heat exposure. Studies have shown increased health risks in urban populations compared with rural or suburban populations in hot weather and a disproportionate impact on more vulnerable social groups. Estimations of the impacts of various mitigation techniques suggest that a range of measures could reduce health impacts from heat and bring other benefits to health and wellbeing. The impact of the UHI on heat-related health is significant, although often overlooked, particularly when considering future impacts associated with climate change. Multiple factors should be considered when designing mitigation measures in urban environments in order to maximise health benefits and avoid unintended negative effects.

  19. Airborne contamination in the indoor environment and its implications for dose

    DEFF Research Database (Denmark)

    Andersson, Kasper Grann; Roed, Jørn; Byrne, M.A.

    2004-01-01

    Previous work has indicated that radiation doses from deposition on human skin, hair and clothing may contribute significantly to the dose received after a major nuclear accident, such as that, which happened at Chernobyl in 1986. The available data was,however, sparse and associated with conside......Previous work has indicated that radiation doses from deposition on human skin, hair and clothing may contribute significantly to the dose received after a major nuclear accident, such as that, which happened at Chernobyl in 1986. The available data was,however, sparse and associated...... on the deposition of contaminant aerosol were examined, and since the previous measurements had indicated that elemental iodine could be a particularly problematiccontaminant, experimental work was additionally undertaken to examine the process of deposition of this species to skin. Since both clearance...... and percutaneous penetration of deposited contaminants could play important roles in determining doses,experimental programmes were dedicated to the identification of parameters of interest in these contexts. Also doses from contamination on different surfaces in the indoor environment have in the past...

  20. Radar rainfall estimation in a hilly environment and implications for runoff modeling

    Science.gov (United States)

    Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko

    2010-05-01

    Radars are known for their ability to obtain a wealth of information about the spatial stormfield characteristics. Unfortunately, rainfall estimates obtained by this instrument are known to be affected by multiple sources of error. Especially for stratiform precipitation systems, the quality of radar rainfall estimates starts to decrease at relatively close ranges. In the current study the hydrological potential of weather radar is analyzed during a winter half-year for the hilly region of the Belgian Ardennes. A correction algorithm is proposed taking into account attenuation, ground clutter, anomalous propagation, the vertical profile of reflectivity (VPR) and advection. No final bias correction with respect to rain gauge data were implemented, because that does not add to a better understanding of the quality of the radar. Largest quality improvements in the radar data are obtained by ground clutter removal. The influence of VPR correction and advection depends on the precipitation system observed. Overall, the radar shows an underestimation as compared to the rain gauges, which becomes smaller after averaging at the scale of the medium-sized Ourthe catchment. Remaining differences between both devices can mainly be attributed to an improper choice of the Z-R relationship. Conceptual rainfall-runoff simulations show similar results using either catchment average radar or rain gauge data, although the largest discharge peak observed, is seriously underestimated when applying radar data. Overall, for hydrological applications corrected weather radar information in a hilly environment can be used up to 70 km during a winter half-year.

  1. Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO{sub 2} transformation

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, Ramasamy [Department of Chemistry, Thiagarajar College, Madurai, Tamilnadu 625 009 (India); National Center for Catalysis Research, Indian Institute of Technology Madras, Chennai, Tamilnadu 600 036 (India); Thamaraichelvan, Arunachalam [Faculty of Allied Health Sciences, Chettinad Hospital & Research Institute, Kelambakkam, Tamilnadu 603 103 (India); Ganesan, Tharumeya Kuppusamy [Department of Chemistry, The American College, Madurai, Tamilnadu 625 002 (India); Viswanathan, Balasubramanian, E-mail: bvnathan@iitm.ac.in [National Center for Catalysis Research, Indian Institute of Technology Madras, Chennai, Tamilnadu 600 036 (India)

    2017-02-28

    Highlights: • On interaction with adsorbate CO{sub 2,} the adsorbent changes its configuration around the metal. • Electron transfer is faster in low coordinative environment of Cu. • CO formation is more favorable on Cu sites with even coordination number. • Cu at coordination number two has a over potential of −0.35 V. - Abstract: Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO{sub 2} to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO{sub 2} to CO at an applied potential of −0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO{sub 2} to various value added chemicals.

  2. Geochemistry of shallow ground water in coastal plain environments in the southeastern United States: implications for aquifer susceptibility

    International Nuclear Information System (INIS)

    Tesoriero, Anthony J.; Spruill, Timothy B.; Eimers, Jo L.

    2004-01-01

    Ground-water chemistry data from coastal plain environments have been examined to determine the geochemical conditions and processes that occur in these areas and assess their implications for aquifer susceptibility. Two distinct geochemical environments were studied to represent a range of conditions: an inner coastal plain setting having more well-drained soils and lower organic carbon (C) content and an outer coastal plain environment that has more poorly drained soils and high organic C content. Higher concentrations of most major ions and dissolved inorganic and organic C in the outer coastal plain setting indicate a greater degree of mineral dissolution and organic matter oxidation. Accordingly, outer coastal plain waters are more reducing than inner coastal plain waters. Low dissolved oxygen (O 2 ) and nitrate (NO 3 - ) concentrations and high iron (Fe) concentrations indicate that ferric iron (Fe (III)) is an important electron acceptor in this setting, while dissolved O 2 is the most common terminal electron acceptor in the inner coastal plain setting. The presence of a wide range of redox conditions in the shallow aquifer system examined here underscores the importance of providing a detailed geochemical characterization of ground water when assessing the intrinsic susceptibility of coastal plain settings. The greater prevalence of aerobic conditions in the inner coastal plain setting makes this region more susceptible to contamination by constituents that are more stable under these conditions and is consistent with the significantly (p 3 - found in this setting. Herbicides and their transformation products were frequently detected (36% of wells sampled), however concentrations were typically low (<0.1 μg/L). Shallow water table depths often found in coastal plain settings may result in an increased risk of the detection of pesticides (e.g., alachlor) that degrade rapidly in the unsaturated zone

  3. Geochemistry of shallow ground water in coastal plain environments in the southeastern United States: Implications for aquifer susceptibility

    Science.gov (United States)

    Tesoriero, A.J.; Spruill, T.B.; Eimers, J.L.

    2004-01-01

    Ground-water chemistry data from coastal plain environments have been examined to determine the geochemical conditions and processes that occur in these areas and assess their implications for aquifer susceptibility. Two distinct geochemical environments were studied to represent a range of conditions: an inner coastal plain setting having more well-drained soils and lower organic carbon (C) content and an outer coastal plain environment that has more poorly drained soils and high organic C content. Higher concentrations of most major ions and dissolved inorganic and organic C in the outer coastal plain setting indicate a greater degree of mineral dissolution and organic matter oxidation. Accordingly, outer coastal plain waters are more reducing than inner coastal plain waters. Low dissolved oxygen (O2) and nitrate (NO 3-) concentrations and high iron (Fe) concentrations indicate that ferric iron (Fe (III)) is an important electron acceptor in this setting, while dissolved O2 is the most common terminal electron acceptor in the inner coastal plain setting. The presence of a wide range of redox conditions in the shallow aquifer system examined here underscores the importance of providing a detailed geochemical characterization of ground water when assessing the intrinsic susceptibility of coastal plain settings. The greater prevalence of aerobic conditions in the inner coastal plain setting makes this region more susceptible to contamination by constituents that are more stable under these conditions and is consistent with the significantly (p<0.05) higher concentrations of NO3- found in this setting. Herbicides and their transformation products were frequently detected (36% of wells sampled), however concentrations were typically low (<0.1 ??g/L). Shallow water table depths often found in coastal plain settings may result in an increased risk of the detection of pesticides (e.g., alachlor) that degrade rapidly in the unsaturated zone.

  4. Atom optics

    International Nuclear Information System (INIS)

    Balykin, V. I.; Jhe, W.

    1999-01-01

    Atom optics, in analogy to neutron and electron optics, deals with the realization of as a traditional elements, such as lenes, mirrors, beam splitters and atom interferometers, as well as a new 'dissipative' elements such as a slower and a cooler, which have no analogy in an another types of optics. Atom optics made the development of atom interferometer with high sensitivity for measurement of acceleration and rotational possible. The practical interest in atom optics lies in the opportunities to create atom microprobe with atom-size resolution and minimum damage of investigated objects. (Cho, G. S.)

  5. Holocene Paleoceanographic Environments at the Chukchi-Alaskan Margin: Implications for Future Changes

    Science.gov (United States)

    Polyak, L.; Nam, S. I.; Dipre, G.; Kim, S. Y.; Ortiz, J. D.; Darby, D. A.

    2017-12-01

    The impacts of the North Pacific oceanic and atmospheric system on the Arctic Ocean result in accelerated sea-ice retreat and related changes in hydrography and biota in the western Arctic. Paleoclimatic records from the Pacific sector of the Arctic are key for understanding the long-term history of these interactions. As opposed to stratigraphically long but strongly compressed sediment cores recovered from the deep Arctic Ocean, sediment depocenters on the Chukchi-Alaskan margin yield continuous, medium to high resolution records formed since the last deglaciation. While early Holocene conditions were non-analogous to modern environments due to the effects of prolonged deglaciation and insufficiently high sea levels, mid to late Holocene sediments are more relevant for recent and modern climate variability. Notably, a large depocenter at the Alaskan margin has sedimentation rates estimated as high as a few millimeters per year, thus providing a decadal to near-annual resolution. This high accumulation can be explained by sediment delivery via the Alaskan Coastal Current originating from the Bering Sea and supposedly controlled by the Aleutian Low pressure center. Preliminary results from sediment cores recovering the last several centuries, along with a comparison with other paleoclimatic proxy records from the Arctic-North Pacific region, indicate a persistent role of the Aleutian Low in the Bering Strait inflow and attendant deposition. More proxy studies are underway to reconstruct the history of this circulation system and its relationship with sea ice extent. The expected results will improve our understanding of natural variability in oceanic and atmospheric conditions at the Chukchi-Alaskan margin, a critical area for modulating the Arctic climate change.

  6. Organophosphorus pollutants (OPP) in aquatic environment at Damietta Governorate, Egypt: implications for monitoring and biomarker responses.

    Science.gov (United States)

    Abdel-Halim, K Y; Salama, A K; El-Khateeb, E N; Bakry, N M

    2006-06-01

    The study was carried out from spring 1999 to spring 2001 to monitor the residue levels of organophosphorus pollutants (OPP) in aquatic environment of the drainage canal surrounding a pesticide factory at Damietta Governorate. Water, sediment, and fish samples were collected at six different seasonal periods. OPPs were analyzed by GLC and confirmed using GC-MS. Chlorpyrifos, chlorpyrifos-methyl, malathion, diazinon, pirimiphos-methyl and profenofos were detected in most samples. Chlorpyrifos was dominant in all water and sediment samples. It was ranged from 24.5 to 303.8 and 0.9 to 303.8 ppb in water and sediment samples, respectively. Diazinon level was slightly similar to chlorpyrifos in fish samples. Data based on the grand total concentration of OPP showed that the most polluted samples were collected either at spring 1999 or autumn 2000. They were 675.5 and 303.8 ppb in water samples and 43.0 and 52.2 ppb in fish collected at spring 1999 and autumn 2000, respectively. The obtained results are in parallel to that found in case of cholinesterase activity where the activity of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was declined at these seasonal period. The activity levels of AChE and BuChE were found to be 77.18% and 59.67% of control at spring 1999 and 78.62% and 85.80% of control, at autumn 2000, respectively. Thus, AChE and BuChE could be used as biomarkers for tracing and biomonitoring OPP pollution.

  7. Management of atom and environment

    International Nuclear Information System (INIS)

    Sethna, H.N.

    1981-01-01

    Principles and policies followed in India on the nuclear power industry to ensure that radiation exposure of workers as well as general public is kept at an acceptable low level are described. (M.G.B.)

  8. Environment

    International Nuclear Information System (INIS)

    McIntyre, A.D.; Turnbull, R.G.H.

    1992-01-01

    The development of the hydrocarbon resources of the North Sea has resulted in both offshore and onshore environmental repercussions, involving the existing physical attributes of the sea and seabed, the coastline and adjoining land. The social and economic repercussions of the industry were equally widespread. The dramatic and speedy impact of the exploration and exploitation of the northern North Sea resources in the early 1970s, on the physical resources of Scotland was quickly realised together with the concern that any environmental and social damage to the physical and social fabric should be kept to a minimum. To this end, a wide range of research and other activities by central and local government, and other interested agencies was undertaken to extend existing knowledge on the marine and terrestrial environments that might be affected by the oil and gas industry. The outcome of these activities is summarized in this paper. The topics covered include a survey of the marine ecosystems of the North Sea, the fishing industry, the impact of oil pollution on seabirds and fish stocks, the ecology of the Scottish coastline and the impact of the petroleum industry on a selection of particular sites. (author)

  9. The Distribution of Antarctic Subglacial Lake Environments With Implications for Their Origin and Evolution

    Science.gov (United States)

    Blankenship, D. D.; Young, D. A.; Carter, S. P.

    2006-12-01

    Ice-penetrating radar records across the Antarctic Ice Sheet show regions with strong flat mirror-like reflections from the subglacial interface that are interpreted to be from subglacial lakes. The majority of subglacial lakes are found in East Antarctica, primarily in topographically low areas of basins beneath the thick ice divides. Occasionally lakes are observed "perched" at higher elevations within local depressions of rough morphological regions. In addition, a correlation between the "onset" of enhanced glacial flow and subglacial lakes was identified. The greatest concentration of known lakes was found in the vicinity of Dome C. A second grouping of lakes lying near Ridge B includes Lake Vostok and several smaller lakes. Subglacial lakes were also discovered near the South Pole, within eastern Wilkes Land, west of the Transantarctic Mountains, and within West Antarctica's Whitmore Mountains. Aside from Lake Vostok, typical lengths of subglacial lakes were found to range from a few to about 20 kilometers. A recent inventory includes 145 subglacial lakes. Approximately 81% of detected lakes lie at elevations less than a few hundred meters above sea level while the majority of the remaining lakes are "perched" at higher elevations. We present the locations from the subglacial lake inventory on local "ice divides" calculated from the satellite derived surface elevations with and find the distance of each lake from these divides. Most significantly, we found that 66% of the lakes identified lie within 50 km of a local ice divide and 88% lie within 100 km of a local divide. In particular, note that lakes located far from the Dome C/Ridge B cluster and even those associated with very narrow catchments lie either on or within a few tens of kilometers of the local divide marked by the catchment boundary. The distance correlation of subglacial lakes with local ice divides leads to a fundamental question for the evolution of subglacial lake environments: Does the

  10. Hydrogen Peroxide Cycling in Acidic Geothermal Environments and Potential Implications for Oxidative Stress

    Science.gov (United States)

    Mesle, M.; Beam, J.; Jay, Z.; Bodle, B.; Bogenschutz, E.; Inskeep, W.

    2014-12-01

    Hydrogen peroxide (H2O2) may be produced in natural waters via photochemical reactions between dissolved oxygen, organic carbon and light. Other reactive oxygen species (ROS) such as superoxide and hydroxyl radicals are potentially formed in environments with high concentrations of ferrous iron (Fe(II), ~10-100 μM) by reaction between H2O2 and Fe(II) (i.e., Fenton chemistry). Thermophilic archaea and bacteria inhabiting acidic iron-oxide mats have defense mechanisms against both extracellular and intracellular peroxide, such as peroxiredoxins (which can degrade H2O2) and against other ROS, such as superoxide dismutases. Biological cycling of H2O2 is not well understood in geothermal ecosystems, and geochemical measurements combined with molecular investigations will contribute to our understanding of microbial response to oxidative stress. We measured H2O2 and other dissolved compounds (Fe(II), Fe(III), H2S, O2), as well as photon flux, pH and temperature, over time in surface geothermal waters of several acidic springs in Norris Geyser Basin, Yellowstone National Park, WY (Beowulf Spring and One Hundred Spring Plain). Iron-oxide mats were sampled in Beowulf Spring for on-going analysis of metatranscriptomes and RT-qPCR assays of specific stress-response gene transcription (e.g., superoxide dismutases, peroxiredoxins, thioredoxins, and peroxidases). In situ analyses show that H2O2 concentrations are lowest in the source waters of sulfidic systems (ca. 1 μM), and increase by two-fold in oxygenated waters corresponding to Fe(III)-oxide mat formation (ca. 2 - 3 μM). Channel transects confirm increases in H2O2 as a function of oxygenation (distance). The temporal dynamics of H2O2, O2, Fe(II), and H2S in Beowulf geothermal waters were also measured during a diel cycle, and increases in H2O2 were observed during peak photon flux. These results suggest that photochemical reactions may contribute to changes in H2O2. We hypothesize that increases in H2O2 and O2

  11. Response of marine copepods to a changing tropical environment: winners, losers and implications

    Directory of Open Access Journals (Sweden)

    Li Lee Chew

    2016-05-01

    . Centropages tenuiremis was likely an introduced species. There was no significant loss in species richness of copepods despite the dramatic changes in community structure. Discussion. Sea warming and other human-induced effects such as eutrophication, acidification and coastal habitat degradation are likely the main factors that have altered copepod community structure. The large-bodied estuarine and coastal calanoid copepods are surmised to be vulnerable to eutrophication and hypoxia, while both resilient and opportunistic species are largely unaffected by, or adaptable to, degraded coastal environments and observed sea surface temperature (SST rise. It is forecasted that SST rise with unmitigated anthropogenic impacts will further reduce large-bodied copepod species the favoured food for fish larvae with dire consequences for coastal fish production.

  12. In-situ environmental (scanning) transmission electron microscopy of catalysts at the atomic level

    International Nuclear Information System (INIS)

    Gai, P L; Boyes, E D

    2014-01-01

    Observing reacting single atoms on the solid catalyst surfaces under controlled reaction conditions is a key goal in understanding and controlling heterogeneous catalytic reactions. In-situ real time aberration corrected environmental (scanning) transmission electron microscopy (E(S)TEM permit the direct imaging of dynamic surface and sub-surface structures of reacting catalysts. In this paper in-situ AC ETEM and AC ESTEM studies under controlled reaction environments of oxide catalysts and supported metal nanocatalysts important in chemical industry are presented. They provide the direct evidence of dynamic processes at the oxide catalyst surface at the atomic scale and single atom dynamics in catalytic reactions. The ESTEM studies of single atom dynamics in controlled reaction environments show that nanoparticles act as reservoirs of ad-atoms. The results have important implications in catalysis and nanoparticle studies

  13. Atom-by-atom assembly

    International Nuclear Information System (INIS)

    Hla, Saw Wai

    2014-01-01

    Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to ‘see’ individual atoms by means of imaging, but is also a tool that is used to ‘touch’ and ‘take’ the atoms, or to ‘hear’ their movements. Therefore, the STM can be considered as the ‘eyes’, ‘hands’ and ‘ears’ of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed. (review article)

  14. The Surface UV Environment on Planets Orbiting M-Dwarfs: Implications for Origins-of-Life Chemistry and Need for Experimental Follow-Up

    Science.gov (United States)

    Ranjan, S.; Wordsworth, R. D.; Sasselov, D. D.

    2017-11-01

    Multiple lines of evidence suggest UV light may have played a key role in the origin of life on Earth. However, temperate M-dwarf planets are UV-poor environments. I discuss the implications for origin-of-life scenarios on M-dwarf planets.

  15. Development of a high flow source of energetic oxygen atoms for material degradation studies. [of Space Shuttles in low earth orbit environments

    Science.gov (United States)

    Caledonia, G. E.; Krech, R. H.

    1985-01-01

    A technique for the generation, in the laboratory, of thermally 'cold', high flux of energetic oxygen atoms is presented. The flux of nearly mono-energetic oxygen atoms is obtained after a laser-induced breakdown of oxygen molecules followed by a rapid expansion of the recombining plasma. The experimental apparatus, the optical and spectral measurements, the O-atom source characterization, and the material degradation studies are discussed. Average oxygen atom velocities of about 5 to 13 km/s are measured with an estimated flux of 10 to the 18th per pulse, over pulse durations of several microseconds. The flow of the O2 gas for about 200 microseconds before applying the laser pulse is found to give best results. It is also found that the energetic O-atom irradiation of sample targets such as Al, Fe, and polyethylene, induces mass removal. In addition, spectral scans of the radiation reveals the existence of two main spectral subsets.

  16. Implications of host genetic variation on the risk and prevalence of infectious diseases transmitted through the environment.

    Science.gov (United States)

    Doeschl-Wilson, Andrea B; Davidson, R; Conington, J; Roughsedge, T; Hutchings, M R; Villanueva, B

    2011-07-01

    Previous studies have shown that host genetic heterogeneity in the response to infectious challenge can affect the emergence risk and the severity of diseases transmitted through direct contact between individuals. However, there is substantial uncertainty about the degree and direction of influence owing to different definitions of genetic variation, most of which are not in line with the current understanding of the genetic architecture of disease traits. Also, the relevance of previous results for diseases transmitted through environmental sources is unclear. In this article a compartmental genetic-epidemiological model was developed to quantify the impact of host genetic diversity on epidemiological characteristics of diseases transmitted through a contaminated environment. The model was parameterized for footrot in sheep. Genetic variation was defined through continuous distributions with varying shape and degree of dispersion for different disease traits. The model predicts a strong impact of genetic heterogeneity on the disease risk and its progression and severity, as well as on observable host phenotypes, when dispersion in key epidemiological parameters is high. The impact of host variation depends on the disease trait for which variation occurs and on environmental conditions affecting pathogen survival. In particular, compared to homogeneous populations with the same average susceptibility, disease risk and severity are substantially higher in populations containing a large proportion of highly susceptible individuals, and the differences are strongest when environmental contamination is low. The implications of our results for the recording and analysis of disease data and for predicting response to selection are discussed.

  17. The Value of Wind Technology Innovation: Implications for the U.S. Power System, Wind Industry, Electricity Consumers, and Environment

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Trieu T [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lantz, Eric J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mowers, Matthew [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wiser, Ryan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-09-21

    Improvements to wind technologies have, in part, led to substantial deployment of U.S. wind power in recent years. The degree to which technology innovation will continue is highly uncertain adding to uncertainties in future wind deployment. We apply electric sector modeling to estimate the potential wind deployment opportunities across a range of technology advancement projections. The suite of projections considered span a wide range of possible cost and technology innovation trajectories, including those from a recent expert elicitation of wind energy experts, a projection based on the broader literature, and one reflecting estimates based on a U.S. DOE research initiative. In addition, we explore how these deployment pathways may impact the electricity system, electricity consumers, the environment, and the wind-related workforce. Overall, our analysis finds that wind technology innovation can have consequential implications for future wind power development throughout the United States, impact the broader electricity system, lower electric system and consumer costs, provide potential environmental benefits, and grow the U.S. wind workforce.

  18. Genotypic variation in grain P loading across diverse rice growing environments and implications for field P balances

    Directory of Open Access Journals (Sweden)

    Elke Vandamme

    2016-09-01

    Full Text Available More than 60% of phosphorus (P taken up by rice (Oryza spp is accumulated in the grains at harvest and hence exported from fields, leading to a continuous removal of P. If P removed from fields is not replaced by P inputs then soil P stocks decline, with consequences for subsequent crops. Breeding rice genotypes with a low concentration of P in the grains could be a strategy to reduce maintenance fertilizer needs and slow soil P depletion in low input systems. This study aimed to assess variation in grain P concentrations among rice genotypes across diverse environments and evaluate the implications for field P balances at various grain yield levels. Multi-location screening experiments were conducted at different sites across Africa and Asia and yield components and grain P concentrations were determined at harvest. Genotypic variation in grain P concentration was evaluated while considering differences in P supply and grain yield using cluster analysis to group environments and boundary line analysis to determine minimum grain P concentrations at various yield levels. Average grain P concentrations across genotypes varied almost 3-fold among environments, from 1.4 to 3.9 mg g-1. Minimum grain P concentrations associated with grain yields of 150, 300 and 500 g m-2 varied between 1.2 and 1.7, 1.3 and 1.8 and 1.7 and 2.2 mg g-1 among genotypes respectively. Two genotypes, Santhi Sufaid and DJ123, were identified as potential donors for low grain P concentration. Improvements in P balances that could be achieved by exploiting this genotypic variation are in the range of less than 0.10 g P m-2 (1 kg P ha-1 in low yielding systems, and 0.15 to 0.50 g P m-2 (1.5-5.0 kg P ha-1 in higher yielding systems. Improved crop management and alternative breeding approaches may be required to achieve larger reductions in grain P concentrations in rice.

  19. Atomic polarizabilities

    International Nuclear Information System (INIS)

    Safronova, M. S.; Mitroy, J.; Clark, Charles W.; Kozlov, M. G.

    2015-01-01

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed

  20. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  1. Atomic physics

    International Nuclear Information System (INIS)

    Armbruster, P.; Beyer, H.; Bosch, F.; Dohmann, H.D.; Kozhuharov, C.; Liesen, D.; Mann, R.; Mokler, P.H.

    1984-01-01

    The heavy ion accelerator UNILAC is well suited to experiments in the field of atomic physics because, with the aid of high-energy heavy ions atoms can be produced in exotic states - that is, heavy atoms with only a few electrons. Also, in close collisions of heavy ions (atomic number Z 1 ) and heavy target atoms (Z 2 ) short-lived quasi-atomic 'superheavy' systems will be formed - huge 'atoms', where the inner electrons are bound in the field of the combined charge Z 1 + Z 2 , which exceeds by far the charge of the known elements (Z <= 109). Those exotic or transient superheavy atoms delivered from the heavy ion accelerator make it possible to study for the first time in a terrestrial laboratory exotic, but fundamental, processes, which occur only inside stars. Some of the basic research carried out with the UNILAC is discussed. This includes investigation of highly charged heavy atoms with the beam-foil method, the spectroscopy of highly charged slow-recoil ions, atomic collision studies with highly ionised, decelerated ions and investigations of super-heavy quasi-atoms. (U.K.)

  2. Ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Hofferberth, S.; Haller, E.

    2005-01-01

    Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

  3. Contexts Paired with Junk Food Impair Goal-Directed Behavior in Rats: Implications for Decision Making in Obesogenic Environments

    Science.gov (United States)

    Kendig, Michael D.; Cheung, Ambrose M. K.; Raymond, Joel S.; Corbit, Laura H.

    2016-01-01

    by a cue paired with chow. This has promising implications for assisting individuals in controlling their eating behavior in environments designed to dysregulate it. PMID:27877118

  4. Contexts Paired with Junk Food Impair Goal-Directed Behavior in Rats: Implications for Decision Making in Obesogenic Environments.

    Science.gov (United States)

    Kendig, Michael D; Cheung, Ambrose M K; Raymond, Joel S; Corbit, Laura H

    2016-01-01

    a cue paired with chow. This has promising implications for assisting individuals in controlling their eating behavior in environments designed to dysregulate it.

  5. Contexts paired with junk food impair goal-directed behaviour in rats: implications for decision making in obesogenic environments

    Directory of Open Access Journals (Sweden)

    Michael D. Kendig

    2016-11-01

    deficit was improved by a cue paired with chow. This has promising implications for assisting individuals in controlling their eating behaviour in environments designed to dysregulate it.

  6. Atomic insight into tribochemical wear mechanism of silicon at the Si/SiO{sub 2} interface in aqueous environment: Molecular dynamics simulations using ReaxFF reactive force field

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Jialin; Ma, Tianbao [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Zhang, Weiwei; Psofogiannakis, George; Duin, Adri C.T. van [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Chen, Lei; Qian, Linmao [Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031 (China); Hu, Yuanzhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Lu, Xinchun, E-mail: xclu@tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2016-12-30

    Highlights: • New ReaxFF reactive force field was applied to simulate the tribochemical wear process at Si/SiO{sub 2} interface. • Wear of silicon atoms is due to the breaking of Si–O–Si bonds and Si–Si–O–Si bond chains on the Si substrate. • Interfacial bridge bonds play an important role during the tribochemical wear process. • Higher pressures applied to the silica phase can cause more Si atoms to be removed by forming more interfacial bridge bonds. • Water plays an opposing role in the wear process because of its both chemical and mechanical effects. - Abstract: In this work, the atomic mechanism of tribochemical wear of silicon at the Si/SiO{sub 2} interface in aqueous environment was investigated using ReaxFF molecular dynamics (MD) simulations. Two types of Si atom removal pathways were detected in the wear process. The first is caused by the destruction of stretched Si–O–Si bonds on the Si substrate surface and is assisted by the attachment of H atoms on the bridging oxygen atoms of the bonds. The other is caused by the rupture of Si–Si bonds in the stretched Si–Si–O–Si bond chains at the interface. Both pathways effectively remove Si atoms from the silicon surface via interfacial Si–O–Si bridge bonds. Our simulations also demonstrate that higher pressures applied to the silica phase can cause more Si atoms to be removed due to the formation of increased numbers of interfacial Si–O–Si bridge bonds. Besides, water plays a dual role in the wear mechanism, by oxidizing the Si substrate surface as well as by preventing the close contact of the surfaces. This work shows that the removal of Si atoms from the substrate is a result of both chemical reaction and mechanical effects and contributes to the understanding of tribochemical wear behavior in the microelectromechanical systems (MEMS) and Si chemical mechanical polishing (CMP) process.

  7. Atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 2 3 Po, 2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 2 3 Po level of helium-like krypton

  8. Atomic oxygen stimulated outgassing

    Science.gov (United States)

    Linton, Roger C.; Reynolds, John M.

    1991-01-01

    The passive Long Duration Exposure Facility (LDEF) Experiment A0034, Atomic Oxygen Simulated Outgassing, consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge and, for reference, to the relative wake environment on the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of the various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and a optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to the RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

  9. Early Atomism

    Indian Academy of Sciences (India)

    https://www.ias.ac.in/article/fulltext/reso/015/10/0905-0925. Keywords. Atomic theory; Avogadro's hypothesis; atomic weights; periodic table; valence; molecular weights; molecular formula; isomerism. Author Affiliations. S Ramasesha1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, ...

  10. Atomic physics

    CERN Document Server

    Born, Max

    1969-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  11. Exotic atoms

    International Nuclear Information System (INIS)

    Backenstoss, G.

    1986-01-01

    Recent developments in the field of exotic atoms are presented. The improved quality of accelerator facilities and experimental techniques leads to a more precise determination of data. This opens new fields in nuclear and particle physics to which exotic atoms may contribute valuable knowledge. (author)

  12. An Examination of Which Implications New Media Platforms Can Have on Study Group Work and Learning Opportunities in the Environment of the Course Information Systems for Business

    DEFF Research Database (Denmark)

    Hougaard, Simone Quach; Trankjær, Mie Bohn; Schlichter, Bjarne Rerup

    2014-01-01

    The Information Society is characterised by its technological development; the many New Media platforms offered on the World Wide Web have changed the communication culture from a traditional one-way transaction to a co-creation culture (Mangold and Faulds 2009). This paper investigates which...... implications New Media platforms – with special emphasis on Blackboard, Facebook, Google Docs and Dropbox – have on study group work in the environment of the course Information Systems for Business (ISB) at Aarhus University. Additionally, it is investigated which opportunities these platforms potentially...... could have on the learning environment at the university, as this could be of significant importance in the future educational system. The research is based on literature about New Media and New Media’s role in collaboration and learning environments. In order to establish some empirical grounding...

  13. Atoms for Power, Health and the Environment. 31st annual conference of the Canadian Nuclear Society and 34th annual conference of the Canadian Nuclear Society and Canadian Nuclear Association

    International Nuclear Information System (INIS)

    2010-01-01

    The 31st Annual Conference of the CNS and 34th Annual Student Conference of the CNS and CNA was held in Montreal, Quebec, Canada on May 24-27, 2010. The theme of the conference, 'Atoms for Power, Health, and the Environment', brought together scientists, engineers, technologists and students interested in all aspects and applications of energy from the atom. The central objective of this conference was to provide a forum for exchange of views on how this technical enterprise can best serve the needs of humanity, now and in the future. There were over 400 attendees and more than 100 technical papers, as well as plenary sessions that addressed broad industrial and commercial developments in the field.

  14. The reaction of atomic hydrogen with germane - Temperature dependence of the rate constant and implications for germane photochemistry in the atmospheres of Jupiter and Saturn

    Science.gov (United States)

    Nava, David F.; Payne, Walter A.; Marston, George; Stief, Louis J.

    1993-01-01

    Studies of the formation and loss processes for GeH4 are required in order to provide data to help determine the major chemical form in which germanium exists in the atmospheres of Jupiter and Saturn. The reaction of hydrogen atoms with germane is one of the most important of these reactions. The absolute rate constant for this reaction as a function of temperature and pressure is studied. Flash photolysis of dilute mixtures of GeH4 in argon, combined with time-resolved detection of H atoms via Lyman alpha resonance fluorescence, is employed to measure the reaction rate. The reaction is shown to be moderately rapid, independent of total pressure, but possessing a positive temperature dependence.

  15. Superradiators created atom by atom

    Science.gov (United States)

    Meschede, Dieter

    2018-02-01

    High radiation rates are usually associated with macroscopic lasers. Laser radiation is “coherent”—its amplitude and phase are well-defined—but its generation requires energy inputs to overcome loss. Excited atoms spontaneously emit in a random and incoherent fashion, and for N such atoms, the emission rate simply increases as N. However, if these atoms are in close proximity and coherently coupled by a radiation field, this microscopic ensemble acts as a single emitter whose emission rate increases as N2 and becomes “superradiant,” to use Dicke's terminology (1). On page 662 of this issue, Kim et al. (2) show the buildup of coherent light fields through collective emission from atomic radiators injected one by one into a resonator field. There is only one atom ever in the cavity, but the emission is still collective and superradiant. These results suggest another route toward thresholdless lasing.

  16. Different effects of surface heterogeneous atoms of porous and non-porous carbonaceous materials on adsorption of 1,1,2,2-tetrachloroethane in aqueous environment.

    Science.gov (United States)

    Chen, Weifeng; Ni, Jinzhi

    2017-05-01

    The surface heterogeneous atoms of carbonaceous materials (CMs) play an important role in adsorption of organic pollutants. However, little is known about the surface heterogeneous atoms of CMs might generate different effect on adsorption of hydrophobic organic compounds by porous carbonaceous materials - activated carbons (ACs) and non-porous carbonaceous materials (NPCMs). In this study, we observed that the surface oxygen and nitrogen atoms could decrease the adsorption affinity of both ACs and NPCMs for 1,1,2,2-tetrachloroethane (TeCA), but the degree of decreasing effects were very different. The increasing content of surface oxygen and nitrogen ([O + N]) caused a sharper decrease in adsorption affinity of ACs (slope of lg (k d /SA) vs [O + N]: -0.098∼-0.16) than that of NPCMs (slope of lg (k d /SA) vs [O + N]: -0.025∼-0.059) for TeCA. It was due to the water cluster formed by the surface hydrophilic atoms that could block the micropores and generate massive invalid adsorption sites in the micropores of ACs, while the water cluster only occupied the surface adsorption sites of NPCMs. Furthermore, with the increasing concentration of dissolved TeCA, the effect of surface area on adsorption affinity of NPCMs for TeCA kept constant while the effect of [O + N] decreased due to the competitive adsorption between water molecule and TeCA on the surface of NPCMs, meanwhile, both the effects of micropore volume and [O + N] on adsorption affinity of ACs for TeCA were decreased due to the mechanism of micropore volume filling. These findings are valuable for providing a deep insight into the adsorption mechanisms of CMs for TeCA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Carcinogenesis model analysis for breast cancer incidence among atomic bomb survivors and the implications for cancer risk estimate for radiological protection

    International Nuclear Information System (INIS)

    Kai, Michiaki; Kusama, Tomoko

    2000-01-01

    Breast cancer incidence is the highest risk due to radiation among atomic bomb survivors. The excess relative risk of the early-onset breast cancer seems to be remarkably high for the youngest age-at-exposure groups. The cancer risk estimate of breast cancer is a current issue in radiological protection. We used a two-stage stochastic model for carcinogenesis to analyze the breast cancer incidence among atomic bomb survivors (Kai, et al. Radiat. Res. 1997). Our purpose is to examine the dependence of radiation risk on age at exposure using the two-stage model and how to transfer it to other populations for radiological protection. We fitted the model assuming that radiation acts as an initiator and that the rate of radiation-induced mutation and background initiation mutation leading to baseline cancer are additive. We took two age-dependence, not attained age but age at exposure, of the spontaneous process into account. First, age-dependence of spontaneous initiation was expressed by a linear model. We also modeled the age-dependence of spontaneous net growth rate of initiated cells by a linear function. As far as radiation-induced initiation is concerned, we took a stepwise function other than a liner function into account. The analysis did not show that the radiation mutation for the youngest age-at-exposure groups below age 10 was higher than for the older groups. Furthermore, the incidence of female breast cancer in Japan is increasing and the birth cohort effect can be observed in atomic bomb survivors. Our model assumed that an acute exposure to atomic radiation can only initiate cancers and do not influence other stages of carcinogenesis, whereas spontaneous initiation and promotion are age-dependent to consider birth cohort effects. When these cohort effects are properly accounted for, the shape of the age-specific incidence curve in Japan is remarkably similar to the age-specific incidence in western populations (shown in figure). Recently Little and

  18. WIRE project- Soil water repellence in biodiverse semi arid environments: new insights and implications for ecological restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; Jordan, Antonio; Zavala, Lorena M.; Stevens, Jason; González-Pérez, Jose Antonio

    2017-04-01

    the canopy of a broad range of plant species composing the dominant vegetation communities of the study areas. Direct analytical pyrolysis (Py-GC/MS) allowed the structural characterization of soil organic matter (SOM) (Jiménez-Morillo et al., 2014). Basic soil physicochemical properties were analysed and soil microbial activity was measured with the 1-day CO2 test, which determine soil microbial respiration rate based on the measurement of the CO2 burst produced after moistening dry soil (Muñoz-Rojas et al., 2016). Results Main results of the project revealed that SWR is strongly correlated to microbial activity, pH and electrical conductivity. In soil samples under Banksia spp., Py-GC/MS analysis showed that SOM had clear signs of alteration (humified) that included a high contribution of stable families like unspecific aromatic compounds and alkane/alkene pairs. However, under Eucalyptus spp. soils showed a less altered SOM with a high relative contribution from lignocellulose (lignin and carbohydrates), together with a low relative content of recalcitrant families. In soil samples from hummock grasslands of the Pilbara region, very low contents of SOM were found. These results point to possible indirect links between organic substances released by roots and soil wettability involving soil microorganisms. Ecological plant strategies and specific adaptations for water uptake in arid and semi-arid ecosystems of WA are likely the main drivers of SWR. ACKNOWLEDGEMENTS This research has been funded by the University of Western Australia (Research Collaboration Award 2015: 'Soil water repellence in biodiverse semi arid environments: new insights and implications for ecological restoration') and the Spanish Ministry of Economy and Competitiveness (research projects GEOFIRE, CGL2012-38655-C04- 01, and POSTFIRE, CGL 2013-47862-C2-1-R. References Doerr SH, Shakesby RA, Walsh RPD. 2000. Soil water repellency: its causes, characteristics and hydrogeomorphological

  19. Atomic politics

    International Nuclear Information System (INIS)

    Skogmar, G.

    1979-01-01

    The authors basic point is that the military and civil sides of atomic energy cannot be separated. The general aim of the book is to analyze both the military and civil branches, and the interdependence between them, of American foreign policy in the atomic field. Atomic policy is seen as one of the most important imstruments of foreign policy which, in turn, is seen against the background of American imperialism in general. Firstly, the book investigates the most important means by which the United States has controlled the development in the nuclear field in other countries. These means include influencing the conditions of access to nuclear resources of various kinds, influencing the flow of technical-economic information and influencing international organizations and treaties bearing on atomic energy. The time period treated is 1945-1973. 1973 is chosen as the end-year of the study mainly because of the new conditions in the whole energy field initiated by the oil crisis in that year. The sources of the empirical work are mainly hearings before the Joint Committee on Atomic Energy of the U.S. Congress and legal material of various kinds. Secondly, the goals of the American policy are analyzed. The goals identified are armament effect, non-proliferation (horizontal), sales, and energy dependence. The relation between the main goals is discussed.The discussion is centered on the interdependence between the military and the civil aspects, conflict and coincidence of various goals, the relation between short-term and long-term goals, and the possibilities of using one goal as pretext for another. Thirdly, some causes of the changes in the atomic policy around 1953 and 1963 are identified. These are the strategic balance, the competitive situation, the capacity (of the American atomic productive apparatus), and the nuclear technological stage. The specific composition of these four factors at the two time-points can explain the changes of policy. (author)

  20. Contesting 'Environment' Through the Lens of Sustainability: Examining Implications for Environmental Education (EE and Education for Sustainable Development (ESD

    Directory of Open Access Journals (Sweden)

    Helen Kopnina

    2014-10-01

    Full Text Available This article reflects on implications of presenting nature as a social construction, and of commodification of nature. The social construction of nature tends to limit significance of nature to human perception of it. Commodification presents nature in strict instrumental terms as 'natural resources', 'natural capital' or 'ecosystem services'. Both construction and commodification exhibit anthropocentric bias in denying intrinsic value of non-human species. This article will highlight the im-portance of a deep ecology perspective, by elaborating upon the ethical context in which construction and commodification of nature occur. Finally, this article will discuss the implications of this ethical context in relation to environmental education (EE and education for sustainable development (ESD.

  1. The Evolution of Phenotypic Plasticity in Spatially Structured Environments: Implications of Intraspecific Competition, Plasticity Costs, and Environmental Characteristics

    OpenAIRE

    Ernande, B.; Dieckmann, U.

    2004-01-01

    We model the evolution of reaction norms focusing on three aspects: frequency dependent selection arising from resource competition, maintenance and production costs of phenotypic plasticity, and three characteristics of environmental heterogeneity (frequency of environments, their intrinsic carrying capacity, and the sensitivity to phenotypic maladaptation in these environments). We show that (i) reaction norms evolve so as to trade adaptation for acquiring resources against cost avoidance; ...

  2. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  3. Implications of crystal-field and intra-atomic interactions for the electronic structure of high-T/sub c/ superconductors

    International Nuclear Information System (INIS)

    The energies of Cu 3d and O 2p ion orbitals in the ion-lattice potentials of La 2 CuO 4 and YBa 2 Cu 3 O 7 , and the intra-atomic energies of various Cu/sup 3+/(3d) 8 configurations, are calculated. The results suggest that electrons removed from the CuO 2 layer to accomodate doping in La 2 CuO 4 or the YBa 2 Cu 3 O 7 stoichiometry come not from the Cu 3d/sub x//sub <2/-y/sup =/'s and their O 2pσ bonding partners but from otherwise filled π-bonding orbitals. The resulting two types of bonds and/or bands may be important for superconductivity

  4. Toward Rational Design of Cu/SSZ-13 Selective Catalytic Reduction Catalysts: Implications from Atomic-Level Understanding of Hydrothermal Stability

    Energy Technology Data Exchange (ETDEWEB)

    Song, James [Institute; The; amp, Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, P.O. Box 646515, Pullman, Washington 99164, United States; Wang, Yilin [Institute; Walter, Eric D. [Environmental; Washton, Nancy M. [Environmental; Mei, Donghai [Institute; Kovarik, Libor [Environmental; Engelhard, Mark H. [Environmental; Prodinger, Sebastian [Institute; Wang, Yong [Institute; The; amp, Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, P.O. Box 646515, Pullman, Washington 99164, United States; Peden, Charles H. F. [Institute; Gao, Feng [Institute

    2017-11-03

    The hydrothermal stability of Cu/SSZ-13 SCR catalysts has been extensively studied, yet atomic level understanding of changes to the zeolite support and the Cu active sites during hydrothermal aging are still lacking. In this work, via the utilization of spectroscopic methods including solid-state 27Al and 29Si NMR, EPR, DRIFTS, and XPS, together with imaging and elemental mapping using STEM, detailed kinetic analyses, and theoretical calculations with DFT, various Cu species, including two types of isolated active sites and CuOx clusters, were precisely quantified for samples hydrothermally aged under varying conditions. This quantification convincingly confirms the exceptional hydrothermal stability of isolated Cu2+-2Z sites, and the gradual conversion of [Cu(OH)]+-Z to CuOx clusters with increasing aging severity. This stability difference is rationalized from the hydrolysis activation barrier difference between the two isolated sites via DFT. Discussions are provided on the nature of the CuOx clusters, and their possible detrimental roles on catalyst stability. Finally, a few rational design principles for Cu/SSZ-13 are derived rigorously from the atomic-level understanding of this catalyst obtained here. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. Computing time was granted by a user proposal at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC). The experimental studies described in this paper were performed in the EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  5. The contamination impact of human exploration to a subterranean environment and the implications for further crewed space exploration

    Science.gov (United States)

    Leuko, Stefan; Rettberg, Petra; De Waele, Jo; Sanna, Laura; Koskinen, Kaisa

    2016-07-01

    The quest of exploring and looking for life in new places is a human desire since centuries. Nowadays, we are not only looking on planet Earth any more, but our endeavours focus on nearby planets in our solar system. It is therefore of great importance to preserve the extra-terrestrial environment and not to contaminate it with terrestrial / human associated bacteria. At this point in time we are not able to send crewed missions to other planets; however, analysing the impact of human exploration on environments is of great planetary protection concern. This can be achieved by obtaining samples from a subterranean environment, where only expert speleologists have access and the human impact is considered very low. For this study, astronauts participating in the 2014 ESA CAVES (Cooperative Adventure for Valuing and Exercising human behaviour and performance Skills) training course, obtained samples from deep within a subterranean environment and returned them to the laboratory for molecular microbial analysis. The diversity of the returned soil samples was analysed by molecular means such as clone library and next-generation sequencing (NGS). It was found that humans have an immense impact on the microbial diversity in the environment. Although the cave system is sparsely entered by humans, a high relative abundance of Staphylococcus spp. and Propionibacteria spp., organisms that are characteristic for human skin, have been recovered. Some samples even showed the presence of human gut associated methanogenic archaea, Methanomassiliicoccus spp. The obtained data from this investigation indicate that human exploration is strongly polluting an environment and may lead to false-positive sign of life on other planets. It is therefore imperative to increase our awareness to this problem as well as work towards new protocols to protect a pristine extraterrestrial environment during exploration.

  6. Atomic physics

    International Nuclear Information System (INIS)

    Held, B.

    1991-01-01

    This general book describes the change from classical physics to quantum physics. The first part presents atom evolution since antiquity and introduces fundamental quantities and elements of relativity. Experiments which have contributed to the evolution of knowledge on matter are analyzed in the second part. Applications of wave mechanics to the study of matter properties are presented in the third part [fr

  7. Atomic Power

    African Journals Online (AJOL)

    Atomic Power. By Denis Taylor: Dr. Taylor was formerly Chief UNESCO Advisor at the University. College, Nairobi, Kenya and is now Professor of Electrical Engineering in the Uni- versity of Strachlyde, Scotland. He is a leading scientist in the electronics field. He was among the British scientists who developed radar during ...

  8. Atomic Power

    African Journals Online (AJOL)

    that atom-produced electricity began to be more economic than electricity produced by conventional means. In the A.G.R., the uranium metal fuel elements are replaced by uranium dioxide, the higher gas temperatures permitting a more efficient steam cycle and allowing several economies. Initially a reactor of this type was ...

  9. Atomic Warrior

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 9. Atomic Warrior. Shabhana Narasimhan. Book Review Volume 6 Issue 9 September 2001 pp 106-109. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/09/0106-0109. Author Affiliations.

  10. Training Math and Science Teacher-Researchers in a Collaborative Research Environment: Implications for Math and Science Education

    Science.gov (United States)

    Kyei-Blankson, Lydia

    2014-01-01

    In this mixed-methods study, the effect of training teacher-researchers in a collaborative research environment is examined for a cohort of teachers enrolled in a Math and Science Partnership (MSP) master's degree program. The teachers describe changes in their research views and in their application of research in practice, and detail the…

  11. 75 FR 20854 - Medical Device Use in the Home Environment: Implications for the Safe and Effective Use of...

    Science.gov (United States)

    2010-04-21

    ..., and caregivers, on the challenges surrounding medical device technology in the home environment. FDA... electronic comments by June 30, 2010. Location: The public workshop will be held at the Hilton Hotel, 8727 Colesville Rd., Silver Spring, MD 20910. The hotel's front desk telephone number is 301-589-5200. Contact...

  12. NASA Satellite Observations: A Unique Asset for the Study of the Environment and Implications for Public Health

    Science.gov (United States)

    Estes Sue M.

    2010-01-01

    This slide presentation highlights how satellite observation systems are assets for studying the environment in relation to public health. It includes information on current and future satellite observation systems, NASA's public health and safety research, surveillance projects, and NASA's public health partners.

  13. Genomic regions in crop-wild hybrids of lettuce are affected differently in different environments: implications for crop breeding

    NARCIS (Netherlands)

    Hartman, Y.; Hooftman, D.A.P.; Uwimana, B.; van de Wiel, C.C.M.; Smulders, M.J.M.; Visser, R.G.F.; van Tienderen, P.H.

    2012-01-01

    Many crops contain domestication genes that are generally considered to lower fitness of crop-wild hybrids in the wild environment. Transgenes placed in close linkage with such genes would be less likely to spread into a wild population. Therefore, for environmental risk assessment of GM crops, it

  14. Genomic regions in crop-wild hybrids of Lettuce are affected differrently in different environments: implications for crop breeding

    NARCIS (Netherlands)

    Hartman, Y.; Hooftman, D.A.P.; Uwimana, B.; Wiel, van de C.C.M.; Smulders, M.J.M.; Visser, R.G.F.; Tienderen, van P.H.

    2012-01-01

    Many crops contain domestication genes that are generally considered to lower fitness of crop–wild hybrids in the wild environment. Transgenes placed in close linkage with such genes would be less likely to spread into a wild population. Therefore, for environmental risk assessment of GM crops, it

  15. The Intersection of Mathematics and Language in the Post-Secondary Environment: Implications for English Language Learners

    Science.gov (United States)

    Choi, Jean; Milburn, Rebecca; Reynolds, Brett; Marcoccia, Philip; Silva, Patrick Justin; Panag, Sikander

    2013-01-01

    Given the increasing number of English Language Learners (ELLs) in post-secondary environments (Roessingh & Douglas, 2012), educational practices such as availability of language support for mathematics should be assessed to ensure that all students' needs are met. To explore the effects of language on mathematics in ELLs, mathematical test…

  16. A model of gene-gene and gene-environment interactions and its implications for targeting environmental interventions by genotype.

    Science.gov (United States)

    Wallace, Helen M

    2006-10-09

    The potential public health benefits of targeting environmental interventions by genotype depend on the environmental and genetic contributions to the variance of common diseases, and the magnitude of any gene-environment interaction. In the absence of prior knowledge of all risk factors, twin, family and environmental data may help to define the potential limits of these benefits in a given population. However, a general methodology to analyze twin data is required because of the potential importance of gene-gene interactions (epistasis), gene-environment interactions, and conditions that break the 'equal environments' assumption for monozygotic and dizygotic twins. A new model for gene-gene and gene-environment interactions is developed that abandons the assumptions of the classical twin study, including Fisher's (1918) assumption that genes act as risk factors for common traits in a manner necessarily dominated by an additive polygenic term. Provided there are no confounders, the model can be used to implement a top-down approach to quantifying the potential utility of genetic prediction and prevention, using twin, family and environmental data. The results describe a solution space for each disease or trait, which may or may not include the classical twin study result. Each point in the solution space corresponds to a different model of genotypic risk and gene-environment interaction. The results show that the potential for reducing the incidence of common diseases using environmental interventions targeted by genotype may be limited, except in special cases. The model also confirms that the importance of an individual's genotype in determining their risk of complex diseases tends to be exaggerated by the classical twin studies method, owing to the 'equal environments' assumption and the assumption of no gene-environment interaction. In addition, if phenotypes are genetically robust, because of epistasis, a largely environmental explanation for shared sibling

  17. CONCERN FOR THE ENVIRONMENT AND ITS IMPLICATIONS FOR THE CONSUMER BEHAVIOUR IN THE SPHERE OF FOOD AND NUTRITION

    Directory of Open Access Journals (Sweden)

    Sylwia Żakowska-Biemans

    2015-09-01

    Full Text Available Care for the environment is driving global developments in the fi eld of food and nutrition, which apply equally to consumption, production and distribution of food. To get insights into changes in consumer behaviour towards food implied by the concern for the environment, quantitative research was carried out on a representative sample of 1000 Polish consumers. The questionnaire contained, among others, variables describing various dimensions of food related lifestyle and willingness to pro-environmental changes in the sphere of food consumption. The data obtained was analysed using cluster analysis and dividing consumers into four segments with different inclinations to engage in behaviour in line with the concept of sustainable consumption. Concern for the environment was most strongly emphasized in the segment of “modern” consumers. Consumers representing this segment were distinguished by attention to environmental issues and at the same time they were willing to pay more for food products with outstanding quality attributes. They attached great importance to the brand when making food purchasing decision. Moreover, they declared more often to buy organic food, and at the same time refrain from ready meals and pre-prepared meal components. The slightest concern for the environment was observed in the segment of “uninvolved” taste-oriented consumers who are interested in new products but less in issues related to food and nutrition. The results of the research highlight the relationship between lifestyle, food choices, and concern for the environment, which can be used in the creation of marketing communication strategy to stimulate sustainable consumption.

  18. Practice environments and job satisfaction and turnover intentions of nurse practitioners: Implications for primary care workforce capacity.

    Science.gov (United States)

    Poghosyan, Lusine; Liu, Jianfang; Shang, Jingjing; D'Aunno, Thomas

    Health care professionals, organizations, and policy makers are calling for expansion of the nurse practitioner (NP) workforce in primary care to assure timely access and high-quality care. However, most efforts promoting NP practice have been focused on state level scope of practice regulations, with limited attention to the organizational structures. We examined NP practice environments in primary care organizations and the extent to which they were associated with NP retention measures. Data were collected through mail survey of NPs practicing in 163 primary care organizations in Massachusetts in 2012. NP practice environment was measured by the Nurse Practitioner Primary Care Organizational Climate Questionnaire, which has four subscales: Professional Visibility, NP-Administration Relations, NP-Physician Relations, and Independent Practice and Support. Two global items measured job satisfaction and NPs' intent to leave their job. We aggregated NP level data to organization level to attain measures of practice environments. Multilevel logistic regression models were used. NPs rated the relationship between NPs and physicians favorably, contrary to the relationship between NPs and administrators. All subscales measuring NP practice environment had similar influence on the outcome variables. With every unit increase in each standardized subscale score, the odds of job satisfaction factors increased about 20% whereas the odds of intention of turnover decreased about 20%. NPs from organizations with higher mean scores on the NP-Administration subscale had higher satisfaction with their jobs (OR = 1.24, 95% CI [1.12, 1.39]) and had lower intent to leave (OR = 0.79, 95% CI [0.70, 0.90]). NPs were more likely to be satisfied with their jobs and less likely to report intent to leave if their organizations support NP practice, favorable relations with physicians and administration, and clear role visibility. Creating productive practice environments that can retain NPs

  19. The influence of the environment of the absorbing atom on the photoelectric yield spectra of beryllium compounds in the soft X-ray region

    International Nuclear Information System (INIS)

    Blokhin, M.A.; Orlova, E.G.; Schweitzer, I.G.

    1981-01-01

    The photoelectric yield spectra (PYS) of beryllium compounds are investigated experimentally. The BeK absorption edge energy position is shown to be affected by the composition not only of the first coordination sphere, but also of the second one. It is found, that the fine structure of the BeK PYS of beryllium fluoride, hydroxide, and acetate is determined by the first coordination sphere and can be interpreted on the basis of electronic structure calculations for the corresponding structure-forming tetrahedra, taking into account their distortions in the real crystal lattice. An essential difference is revealed in the fine structure of the initial region of the BeK photoelectric yield spectra of the compounds Na 2 BeF 4 , K 2 BeF 4 , BeO, BeSO 4 . 4 H 2 O, BeSiO 3 , and Be 3 (PO 4 ) 2 as compared with the spectra of BeF 2 , Be(OOCCH 3 ) 2 and Be(OH) 2 . This difference is displayed in the presence of a second line group at a distance of 4 to 5 eV from the first near-the-edge group and is due to a strong influence of the second coordination sphere atoms on the formation of fine structure near the beryllium K absorption edge. (author)

  20. Suberythemal Sun Exposures at Swedish Schools Depend on Sky Views of the Outdoor Environments - Possible Implications for Pupils' Health

    DEFF Research Database (Denmark)

    Pagels, Peter; Wester, Ulf; Söderström, Margareta

    2016-01-01

    , offer enough shade to protect children from overexposure during seasons with potentially harmful solar UV radiation. Pupils' outdoor stay may be extended during September and March. In May extended outdoor stay of the youngest pupils requires a more UVR-protective environment.......More scheduled outdoor stay is increasingly advocated for school children. This study measured 2nd, 5th and 8th graders' erythemal UV-exposure in September, March and May at four Swedish schools. We related those exposures, as fractions of total available ambient radiation, to the schools outdoor...... environments differing in amount of shade, vegetation, and peripheral city-scape quantified as percentage of free sky view calculated from fish-eye photographs. Exposures correlated with the sky views (with exceptions in May) and were suberythemal. The exposures were also below the threshold limit...

  1. Conference on Early Mars: Geologic and Hydrologic Evolution, Physical and Chemical Environments, and the Implications for Life

    Science.gov (United States)

    Clifford, S. M. (Editor); Treiman, A. H. (Editor); Newsom, H. E. (Editor); Farmer, J. D. (Editor)

    1997-01-01

    Topics considered include: Geology alteration and life in an extreme environment; developing a chemical code to identify magnetic biominerals; effect of impacts on early Martin geologic evolution; spectroscopic identification of minerals in Hematite-bearing soils and sediments; exopaleontology and the search for a Fossil record on Mars; geochemical evolution of the crust of Mars; geological evolution of the early earth;solar-wind-induced erosion of the Mars atmosphere. Also included geological evolution of the crust of Mars.

  2. Did Eucalyptus contribute to environment degradation? Implications from a dispute on causes of severe drought in Yunnan and Guizhou, China

    OpenAIRE

    WenJun Zhang

    2012-01-01

    Various viewpoints were proposed to explain the causes of recent years' severe drought occurred in Yunnan and Guizhou, China. In general there are two parties of viewpoints, the Eucalyptus cause and climate change cause. I think Yunnan-Guizhou drought has been mainly caused by abnormal climate change. Eucalyptus was not significant in the formation of Yunnan-Guizhou drought. However, the forestation effect of Eucalyptus in China was not good. Environment quality and biodiversity in Eucalyptus...

  3. Effects of captive environment on Sumatran Tigers (Panthera tigris sumatrae) behaviour Implications of ex-situ conservation

    OpenAIRE

    Gomes, Diana Inês Oliveira

    2018-01-01

    In the past few years, the number of people fighting against the captivity of animals has increased. Many pro-animal organisations fight to close zoos and wildlife parks and ask for the releasing of those animals back into the wild. Wild animals are maintained in zoological facilities for purposes of education, conservation, research and recreation. Although zoos consist of captive environments (that are correlated to behaviour alterations and stereotypical movements), they prove themselves t...

  4. A model of gene-gene and gene-environment interactions and its implications for targeting environmental interventions by genotype

    OpenAIRE

    Wallace Helen M

    2006-01-01

    Abstract Background The potential public health benefits of targeting environmental interventions by genotype depend on the environmental and genetic contributions to the variance of common diseases, and the magnitude of any gene-environment interaction. In the absence of prior knowledge of all risk factors, twin, family and environmental data may help to define the potential limits of these benefits in a given population. However, a general methodology to analyze twin data is required becaus...

  5. Developments in radiological protection of the environment and a commentary on its implications for new build of nuclear reactors

    International Nuclear Information System (INIS)

    Brownless, George; Lazo, Ted

    2008-01-01

    Full text: Development of radiological protection of non-human biota continues to be the focus of much interest and differing views amongst the radiological protection community. To nurture discussion of these developments, the Nuclear Energy Agency's Committee on Radiological Protection and Public Health is taking the lead in organising coverage of a spectrum of views on the topic at the International Conference on Radioecology and Radioactivity in the Environment (Bergen, 2008), with the aim of assisting the international community to construct a consensual, fit-for-purpose approach. To support discussion of these views, the session will also include scientific presentations and reports from implementers. This paper will report on these developments, based principally on the session at the Conference but also other activities in which NEA participates, to provide an up-to-date summary in this area including progress in developing understanding of how radiological protection of the environment will be implemented for the three exposure situations - planned, existing and emergency - set out in the new ICRP general recommendations. Furthermore, given the NEA's mandate across the civil nuclear energy field, the paper will give a commentary on how developments in radiological protection of the environment may interplay with new build of nuclear power plants. (author)

  6. Chance and necessity in biochemistry: implications for the search for extraterrestrial biomarkers in Earth-like environments.

    Science.gov (United States)

    Davila, Alfonso F; McKay, Christopher P

    2014-06-01

    In this paper, we examine a restricted subset of the question of possible alien biochemistries. That is, we look into how different life might be if it emerged in environments similar to that required for life on Earth. We advocate a principle of chance and necessity in biochemistry. According to this principle, biochemistry is in some fundamental way the sum of two processes: there is an aspect of biochemistry that is an endowment from prebiotic processes, which represents the necessity, plus an aspect that is invented by the process of evolution, which represents the chance. As a result, we predict that life originating in extraterrestrial Earth-like environments will share biochemical motifs that can be traced back to the prebiotic world but will also have intrinsic biochemical traits that are unlikely to be duplicated elsewhere as they are combinatorially path-dependent. Effective and objective strategies to search for biomarkers, and evidence for a second genesis, on planets with Earth-like environments can be built based on this principle.

  7. Ambientes virtuais de aprendizagem: implicações epistemológicas Virtual learning environments: epistemological implications

    Directory of Open Access Journals (Sweden)

    Vera Menezes de O Paiva

    2010-12-01

    Full Text Available Este texto apresenta algumas visões epistemológicas - objetivismo, subjetivismo e experiencialismo -, em uma tentativa de compreender os conceitos de conhecimento e de aprendizagem subjacentes à construção de ambientes virtuais de aprendizagem. Apresenta, também, uma descrição de três plataformas de aprendizagem gratuitas - AulaNet, Moodle e TeleEduc - e enfatiza que outras ferramentas do internet pode ser adicionadas a esses ambientes educacionais virtuais, de forma a propiciar mais experiências de aprendizagem. Finalmente, conclui que o ambiente virtual retira os professores do palco da aprendizagem, pois eles também podem aprender com os alunos.This text presents some epistemological views - objectivism, subjectivism and experientialism - aiming at understanding the concepts of knowledge and learning which underlay the construction of virtual learning environments. It also presents a description of three free learning software - AulaNet, Moodle and TeleEduc - and emphasizes that other internet tools can be added to those virtual educational environments in order to offer more learning experiences. Finally, it concludes that learning environments remove teachers from the learning stage as they can also learn with the students.

  8. Health and productivity gains from better indoor environments and their implications for the U.S. Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William J.

    2000-10-01

    A substantial portion of the US population suffers frequently from communicable respiratory illnesses, allergy and asthma symptoms, and sick building syndrome symptoms. We now have increasingly strong evidence that changes in building design, operation, and maintenance can significantly reduce these illnesses. Decreasing the prevalence or severity of these health effects would lead to lower health care costs, reduced sick leave, and shorter periods of illness-impaired work performance, resulting in annual economic benefits for the US in the tens of billions of dollars. Increasing the awareness of these potential health and economic gains, combined with other factors, could help bring about a shift in the way we design, construct, operate, and occupy buildings. The current goal of providing marginally adequate indoor environments could be replaced by the goal of providing indoor environments that maximize the health, satisfaction, and performance of building occupants. Through research and technology transfer, DOE and its contractors are well positioned to help stimulate this shift in practice and, consequently, improve the health and economic well-being of the US population. Additionally, DOE's energy-efficiency interests would be best served by a program that prepares for the potential shift, specifically by identifying and promoting the most energy-efficient methods of improving the indoor environment. The associated research and technology transfer topics of particular relevance to DOE are identified and discussed.

  9. From a genetic predisposition to an interactive predisposition: rethinking the ethical implications of screening for gene-environment interactions.

    Science.gov (United States)

    Tabery, James

    2009-02-01

    In a widely acclaimed study from 2002, researchers found a case of gene-environment interaction for a gene controlling neuroenzymatic activity (low vs. high), exposure to childhood maltreatment, and antisocial personality disorder (ASPD). Cases of gene-environment interaction are generally characterized as evincing a genetic predisposition; for example, individuals with low neuroenzymatic activity are generally characterized as having a genetic predisposition to ASPD. I first argue that the concept of a genetic predisposition fundamentally misconstrues these cases of gene-environment interaction. This misconstrual will be diagnosed, and then a new concept--interactive predisposition--will be introduced. I then show how this conceptual shift reconfigures old questions and raises new questions for genetic screening. Attempts to screen embryos or fetuses for the gene associated with low neuroenzymatic activity with an eye toward selecting against the low-activity variant fall prey to the myth of pre-environmental prediction; attempts to screen newborns for the gene associated with low neuroenzymatic activity with an eye toward early intervention will have to face the interventionist's dilemma.

  10. Gas-phase ion/molecule isotope-exchange reactions: methodology for counting hydrogen atoms in specific organic structural environments by chemical ionization mass spectrometry

    International Nuclear Information System (INIS)

    Hunt, D.F.; Sethi, S.K.

    1980-01-01

    Ion/molecule reactions are described which facilitate exchange of hydrogens for deuteriums in a variety of different chemical environments. Aromatic hydrogens in alkylbenzenes, oxygenated benzenes, m-toluidine, m-phenylenediamine, thiophene, and several polycyclic aromatic hydrocarbons and metallocenes are exchanged under positive ion CI conditions by using either D 2 O, EtOD, or ND 3 as the reagent gas. Aromatic hydrogens, benzylic hydrogens, and hydrogens on carbon adjacent to carbonyl groups suffer exchange under negative ion CI conditions in ND 3 , D 2 O, and EtOD, respectively. A possible mechanism for the exchange process is discussed. 1 figure, 2 tables

  11. Legacy and alternative flame retardants in Norwegian and UK indoor environment: Implications of human exposure via dust ingestion.

    Science.gov (United States)

    Kademoglou, Katerina; Xu, Fuchao; Padilla-Sanchez, Juan Antonio; Haug, Line Småstuen; Covaci, Adrian; Collins, Chris D

    2017-05-01

    Indoor dust has been acknowledged as a major source of flame retardants (FRs) and dust ingestion is considered a major route of exposure for humans. In the present study, we investigated the presence of PBDEs and alternative FRs such as emerging halogenated FRs (EHFRs) and organophosphate flame retardants (PFRs) in indoor dust samples from British and Norwegian houses as well as British stores and offices. BDE209 was the most abundant PBDE congener with median concentrations of 4700ngg -1 and 3400ngg -1 in UK occupational and house dust, respectively, 30 and 20 fold higher than in Norwegian house dust. Monomeric PFRs (m-PFRs), including triphenyl phosphate (TPHP), tris(chloropropyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) dominated all the studied environments. To the best of our knowledge, this is the first report of isodecyldiphenyl phosphate (iDPP) and trixylenyl phosphate (TXP) in indoor environments. iDPP was the most abundant oligomeric PFR (o-PFR) in all dust samples, with median concentrations one order of magnitude higher than TXP and bisphenol A bis(diphenyl phosphate (BDP). iDPP and TXP worst-case scenario exposures for British workers during an 8h exposure in the occupational environment were equal to 34 and 1.4ngkgbw -1 day -1 , respectively. The worst-case scenario for BDE209 estimated exposure for British toddlers (820ngkgbw -1 day -1 ) did not exceeded the proposed reference dose (RfD) (7000ngkgbw -1 day -1 ), while exposures for sum of m-PFRs (Σm-PFRs) in British toddlers and adults (17,900 and 785ngkgbw -1 day -1 respectively) were an order of magnitude higher than for Norwegian toddlers and adults (1600 and 70ngkgbw -1 day -1 ). Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. An enriched rearing environment calms adult male rat sexual activity: implication for distinct serotonergic and hormonal responses to females.

    Directory of Open Access Journals (Sweden)

    Susumu Urakawa

    Full Text Available Early life events induce alterations in neural function in adulthood. Although rearing in an enriched environment (EE has a great impact on behavioral development, the effects of enriched rearing on sociosexual behavior remain unclear. In this study, we investigated the effects of rearing in an EE on male copulatory behavior and its underlying neurobiological mechanisms in Wistar-Imamichi rats. Three-week-old, recently weaned rats were continuously subjected to a standard environment (SE or an EE comprised of a large cage with several objects, such as toys, tunnels, ladders, and a running wheel. After 6 weeks, rats reared in an EE (EE rats showed decreased sexual activity compared with rats reared in a SE (SE rats. This included a lower number of ejaculations and longer latencies in three consecutive copulatory tests. In addition, EE rats showed decreased emotional responsiveness and less locomotor behavior in an open field. In a runway test, on the other hand, sexual motivation toward receptive females in EE males was comparable to that of SE males. Furthermore, following exposure to a female, increases in serotonin levels in the nucleus accumbens and the striatum were significantly suppressed in EE males, whereas dopaminergic responses were similar between the groups. Female-exposure-induced increases in the levels of plasma corticosterone and testosterone were also suppressed in EE rats compared to SE rats. These data suggest that rearing in an EE decreases male copulatory behavior, and serotonin and hormonal regulating systems may regulate the differences in sociosexual interactions that result from distinct rearing environments.

  13. Substance Use and HIV Among Female Sex Workers and Female Prisoners: Risk Environments and Implications for Prevention, Treatment, and Policies.

    Science.gov (United States)

    Strathdee, Steffanie A; West, Brooke S; Reed, Elizabeth; Moazen, Babak; Moazan, Babak; Azim, Tasnim; Dolan, Kate

    2015-06-01

    Female sex workers (FSWs) and female prisoners experience elevated HIV prevalence relative to the general population because of unprotected sex and unsafe drug use practices, but the antecedents of these behaviors are often structural in nature. We review the literature on HIV risk environments for FSWs and female prisoners, highlighting similarities and differences in the physical, social, economic, and policy/legal environments that need to be understood to optimize HIV prevention, treatment, and policy responses. Sex work venues, mobility, gender norms, stigma, debt, and the laws and policies governing sex work are important influences in the HIV risk environment among FSWs, affecting their exposure to violence and ability to practice safer sex and safer drug use behaviors. Female prisoners are much more likely to have a drug problem than do male prisoners and have higher HIV prevalence, yet are much less likely to have access to HIV prevention and treatment and access to drug treatment in prison. Women who trade sex or are imprisoned and engage in substance use should not be considered in separate silos because sex workers have high rates of incarceration and many female prisoners have a history of sex work. Repeated cycles of arrest, incarceration, and release can be socially and economically destabilizing for women, exacerbating their HIV risk. This dynamic interplay requires a multisectoral approach to HIV prevention and treatment that appreciates and respects that not all women are willing, able, or want to stop sex work or drug use. Women who engage in sex work, use drugs, or are imprisoned come from all communities and deserve sustained access to HIV prevention and treatment for substance use and HIV, helping them and their families to lead healthy and satisfying lives.

  14. The Microbiome of the Built Environment and Human Behavior: Implications for Emotional Health and Well-Being in Postmodern Western Societies.

    Science.gov (United States)

    Stamper, C E; Hoisington, A J; Gomez, O M; Halweg-Edwards, A L; Smith, D G; Bates, K L; Kinney, K A; Postolache, T T; Brenner, L A; Rook, G A W; Lowry, C A

    2016-01-01

    It is increasingly evident that inflammation is an important determinant of cognitive function and emotional behaviors that are dysregulated in stress-related psychiatric disorders, such as anxiety and affective disorders. Inflammatory responses to physical or psychological stressors are dependent on immunoregulation, which is indicated by a balanced expansion of effector T-cell populations and regulatory T cells. This balance is in part driven by microbial signals. The hygiene or "old friends" hypothesis posits that exposure to immunoregulation-inducing microorganisms is reduced in modern urban societies, leading to an epidemic of inflammatory disease and increased vulnerability to stress-related psychiatric disorders. With the global trend toward urbanization, humans are progressively spending more time in built environments, thereby, experiencing limited exposures to these immunoregulatory "old friends." Here, we evaluate the implications of the global trend toward urbanization, and how this transition may affect human microbial exposures and human behavior. © 2016 Elsevier Inc. All rights reserved.

  15. Atom-surface potentials and atom interferometry

    International Nuclear Information System (INIS)

    Babb, J.F.

    1998-01-01

    Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

  16. Submicron Particles during Macro- and Micro-Weldings Procedures in Industrial Indoor Environments and Health Implications for Welding Operators

    Directory of Open Access Journals (Sweden)

    Pasquale Avino

    2015-06-01

    Full Text Available One of the emerging risks in the engineering and electronic industries is the exposure of workers to ultrafine particles during (micro-welding operations, i.e., processes used for joining two metal parts heated locally, which constitute the base metal, with or without addition of another metal which is the filler metal, melted between the edges to be joined. The process is accompanied by formation of metallic fumes arising from the molten metal as well as by the emission of metal fumes of variable composition depending on the alloys welded and fused. The aim of this paper is to investigate the number, concentration and size distribution of submicron particles produced by (micro-welding processes. Particle number size distribution is continuously measured during (micro-welding operations by means of two instruments, i.e., Fast Mobility Particle Sizer and Nanoparticle Surface Area Monitor. The temporal variation of the particle number size distribution across the peaks evidences the strong and fast-evolving contribution of nucleation mode particles: peak values are maintained for less than 10 s. The implication of such contribution on human health is linked to the high deposition efficiency of submicronic particles in the alveolar interstitial region of the human respiratory system, where gas exchange occurs.

  17. A systematic review of built environment factors related to physical activity and obesity risk: implications for smart growth urban planning.

    Science.gov (United States)

    Durand, C P; Andalib, M; Dunton, G F; Wolch, J; Pentz, M A

    2011-05-01

    Smart growth is an approach to urban planning that provides a framework for making community development decisions. Despite its growing use, it is not known whether smart growth can impact physical activity. This review utilizes existing built environment research on factors that have been used in smart growth planning to determine whether they are associated with physical activity or body mass. Searching the MEDLINE, Psycinfo and Web-of-Knowledge databases, 204 articles were identified for descriptive review, and 44 for a more in-depth review of studies that evaluated four or more smart growth planning principles. Five smart growth factors (diverse housing types, mixed land use, housing density, compact development patterns and levels of open space) were associated with increased levels of physical activity, primarily walking. Associations with other forms of physical activity were less common. Results varied by gender and method of environmental assessment. Body mass was largely unaffected. This review suggests that several features of the built environment associated with smart growth planning may promote important forms of physical activity. Future smart growth community planning could focus more directly on health, and future research should explore whether combinations or a critical mass of smart growth features is associated with better population health outcomes. © 2011 The Authors. obesity reviews © 2011 International Association for the Study of Obesity.

  18. The aqueous photodegradation of fenitrothion under various agricultural plastics: implications for pesticide longevity in agricultural 'micro-environments'.

    Science.gov (United States)

    Weber, Jan; Halsall, Crispin J; Wargent, Jason J; Paul, Nigel D

    2009-06-01

    Plastic cladding is increasingly used in agriculture to create micro-environments to improve crop yield/growth. Many of these plastics can alter the solar light spectrum by inhibiting or reducing the transmittance of certain parts of the solar spectrum. In this study, we investigated the aqueous photolysis of fenitrothion, under a selection of different plastic films commonly used in agriculture. Three different grades of polyethylene film were used: 'standard', 'transparent' and 'opaque'. The transmittance of light wavelengths in the UV region (290-400 nm), measured with a spectroradiometer, was found to decrease in the order of transparent>standard>opaque. Fenitrothion, an organophosphorothioate insecticide possesses molar absorptivity in the solar wavelength range of 290-400 nm. Aqueous first order degradation rate constants for fenitrothion determined over a 12 h period were found to be considerably less for those experiments conducted under the standard and opaque plastic films, compared to the transparent film and no-film control. The experiments were conducted in an Atlas Suntest solar simulator using a UV-filtered Xenon arc lamp to simulate sunlight. The first order half-life for fenitrothion was 100 and 250 h under the standard and opaque films, respectively, compared to approximately 10 h for the transparent film and no-film experiments. Our results suggest that pesticide longevity could be greatly extended within these plastic micro-environments, especially for those chemicals which may degrade/transform via photolytic or photochemical pathways.

  19. Did Eucalyptus contribute to environment degradation? Implications from a dispute on causes of severe drought in Yunnan and Guizhou, China

    Directory of Open Access Journals (Sweden)

    WenJun Zhang

    2012-06-01

    Full Text Available Various viewpoints were proposed to explain the causes of recent years' severe drought occurred in Yunnan and Guizhou, China. In general there are two parties of viewpoints, the Eucalyptus cause and climate change cause. I think Yunnan-Guizhou drought has been mainly caused by abnormal climate change. Eucalyptus was not significant in the formation of Yunnan-Guizhou drought. However, the forestation effect of Eucalyptus in China was not good. Environment quality and biodiversity in Eucalyptus plantation forests has been degrading in last decades. Enhancement of alleopathy of Eucalyptus trees under drought conditions would partly contribute to biodiversity reduction and environment degradation in Eucalyptus plantation forests. For existing Eucalyptus plantation forests of Yunnan, I suggest that some improvement measures should be adopted. Artificial weeding and cleaning in Eucalyptus plantation forests should be banned. Density of Eucalyptus trees needs to be reduced. Biodiversity should be artificially improved in Eucalyptus plantation forests. In the future, the mountains and lands with better vegetation cover must not be reclaimed for Eucalyptus planting. Eucalyptus plantation forests should be made in barren mountains and lands with poor biodiversity.

  20. Macromolecular crowding enhances the binding of superoxide dismutase to xanthine oxidase: implications for protein-protein interactions in intracellular environments.

    Science.gov (United States)

    Zhou, Yu-Ling; Liao, Jun-Ming; Chen, Jie; Liang, Yi

    2006-01-01

    Physiological medium constitutes a crowded environment that serves as the field of action for protein-protein interaction in vivo. Measuring protein-protein interaction in crowded solutions can mimic this environment. Here we report the application of fluorescence spectroscopy and resonant mirror biosensor to investigate the interactions of bovine milk xanthine oxidase and bovine erythrocyte copper, zinc-superoxide dismutase in crowded solutions. Four nonspecific high molecular mass crowding agents, poly(ethylene glycol) 2000 and 20,000, Ficoll 70, and dextran 70, and one low molecular mass compound, glycerol, are used. Superoxide dismutase shows a strong and macromolecular crowding agent concentration-dependent binding affinity to xanthine oxidase. Addition of high concentrations of such high molecular mass crowding agents increases the binding constant remarkably and thus stabilizes superoxide dismutase activity, compared to those in the absence of crowding agents. In contrast, glycerol has little effect on the binding constant and decreases superoxide dismutase activity over the same concentration range. Such a pattern suggests that the enhancing effects of polymers and polysaccharides on the binding are due to macromolecular crowding. Taken together, these results indicate that macromolecular crowding enhances the binding of superoxide dismutase to xanthine oxidase and is favorable to the function of superoxide dismutase.

  1. Fossilization potential of iron-bearing minerals in acidic environments of Rio Tinto, Spain: Implications for Mars exploration

    Science.gov (United States)

    Fernández-Remolar, David C.; Knoll, Andrew H.

    2008-03-01

    Acidic waters of the Rio Tinto, southwestern Spain, evaporate seasonally, precipitating a variety of iron sulfide and oxide minerals. Schwertmannite and nanophase goethite form thin laminae on biological and detrital grain surfaces, replicating, among other things, the morphologies of insect cuticle, plant tissues, fungi, algae, and bacteria. Intergrain cements also incorporate bacterial cells and filaments. Other sulfate minerals precipitated in Rio Tinto environments are transient and contribute little to short-term preservation. Because the Rio Tinto has been cutting its current valley for several million years, terrace deposits provide a window on longer term fossil preservation. Early and later diagenesis are recorded in terrace deposits formed about one thousand and two million years ago, respectively. The sedimentary structures and mineralogies of these deposits suggest that they formed under physical and chemical conditions comparable to those of modern Rio Tinto sediments. The terrace deposits show quantitative loss of sulfate minerals, increasing crystallinity of goethite and, in the older terrace, replacement of goethite by hematite. Fossils formed originally by schwertmannite and nanophase goethite replication persist through diagenesis, preserving a long term record of local biological diversity. Fossil preservation by iron oxides in the acidic environment of Rio Tinto suggests that if life was present when sedimentary rocks formed at Meridiani Planum, Mars, precipitated minerals could record their presence.

  2. Do GIS-derived measures of fast food retailers convey perceived fast food opportunities? Implications for food environment assessment.

    Science.gov (United States)

    Barnes, Timothy L; Colabianchi, Natalie; Freedman, Darcy A; Bell, Bethany A; Liese, Angela D

    2017-01-01

    Geographic information systems (GISs) have been used to define fast food availability, with higher availability perhaps promoting poorer quality diets. Alternative measures involve perceptions; however, few studies have examined associations between GIS-derived and perceived measures of the food environment. Telephone surveys of 705 participants within an eight-county region in South Carolina were analyzed using logistic regression to examine relationships between geographic presence of and distance to various types of food retailers and perceived fast food availability. The mean distance to the nearest fast food restaurant was 6.1 miles, with 16% of participants having a fast food restaurant within 1 mile of home. The geographic presence of and distance to all food retailer types were significantly associated with perceived availability of fast food in unadjusted models. After adjustment, only the presence of a fast food restaurant or pharmacy was significantly associated with greater odds of higher perceived availability of fast food. Greater odds of lower perceived availability of fast food were observed with the presence of a dollar store and increasing distance to the nearest supermarket or pharmacy. Measures of fast food availability, whether objective or perceived, may not be interchangeable. Researchers should carefully decide on the appropriate measurement tool-GIS-derived or perceived-in food environment studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Relation between modern pollen rain, vegetation and climate in northern China: Implications for quantitative vegetation reconstruction in a steppe environment.

    Science.gov (United States)

    Ge, Yawen; Li, Yuecong; Bunting, M Jane; Li, Bing; Li, Zetao; Wang, Junting

    2017-05-15

    Vegetation reconstructions from palaeoecological records depend on adequate understanding of relationships between modern pollen, vegetation and climate. A key parameter for quantitative vegetation reconstructions is the Relative Pollen Productivity (RPP). Differences in both environmental and methodological factors are known to alter the RPP estimated significantly, making it difficult to determine whether the underlying pollen productivity does actually vary, and if so, why. In this paper, we present the results of a replication study for the Bashang steppe region, a typical steppe area in northern China, carried out in 2013 and 2014. In each year, 30 surface samples were collected for pollen analysis, with accompanying vegetation survey using the "Crackles Bequest Project" methodology. Sampling designs differed slightly between the two years: in 2013, sites were located completely randomly, whilst in 2014 sampling locations were constrained to be within a few km of roads. There is a strong inter-annual variability in both the pollen and the vegetation spectra therefore in RPPs, and annual precipitation may be a key influence on these variations. The pollen assemblages in both years are dominated by herbaceous taxa such as Artemisia, Amaranthaceae, Poaceae, Asteraceae, Cyperaceae, Fabaceae and Allium. Artemisia and Amaranthaceae pollen are significantly over-represented for their vegetation abundance. Poaceae, Cyperaceae and Fabaceae seem to have under-represented pollen for vegetation with correspondingly lower RPPs. Asteraceae seems to be well-represented, with moderate RPPs and less annual variation. Estimated Relevant Source Area of Pollen (RSAP) ranges from 2000 to 3000m. Different sampling designs have an effect both on RSAP and RPPs and random sample selection may be the best strategy for obtaining robust estimates. Our results have implications for further pollen-vegetation relationship and quantitative vegetation reconstruction research in typical steppe

  4. Paleocene calcareous nannofossils biostratigraphy from the Sergipe Sub-basin, northeastern Brazil: Implications for this depositional environment

    Science.gov (United States)

    Andrade Oliveira, Geize Carolinne Correia; de Oliveira, Rick Souza; Monte Guerra, Rodrigo; de Lima Filho, Mario Ferreira

    2018-03-01

    This study reports on the biostratigraphy of Paleocene calcareous nannofossils and paleoenvironmental inferences based on five wells drilled on the offshore portion of the Sergipe Sub-basin. Five biostratigraphic zones were defined for the Paleocene in zones of Brazilian continental margin basins N-305, N-307, N-330, N-340 and N-350, and four hiatuses were identified based on the absence of marker species. These hiatuses were interpreted as excavations originated by turbulent to hyperpycnal flows, revealing an important application of biostratigraphy to better understand depositional environments that are often limited by little variation in lithology or low variation in the well log patterns. In Paleoecological terms, the Sergipe Sub-basin, in the Paleocene, experienced geological and environmental events similar to those of other sedimentary basins on the eastern passive continental margin of Brazil, but has a more complete biostratigraphic record of calcareous nannofossils.

  5. Environmental health assessment of primary schools in southeastern Nigeria: implication for a healthy school environment in developing countries.

    Science.gov (United States)

    Ezeonu, C T; Anyansi, M N

    2010-01-01

    In this cross-sectional descriptive study, we used a validated school health program evaluation scale (SHPE) to assess the environmental health status of primary schools in Ebonyi State, southeastern Nigeria. Parameters assessed included water supply, sewage and refuse disposal, school building ventilation, lighting and seating, as well as the availability of toilet tissue, basins for washing hands, regular cleaning of toilets, and so forth. Of all the schools assessed, only two schools, both private, attained the minimum acceptable SHPE score of 57. The mean SHPE score of the private schools (50.40) was significantly higher than that of the public schools (28.69) (t-test, p=.00). Policy reforms are needed that would ensure a healthy primary school environment in Nigeria and in other developing countries with similar settings.

  6. The future implications of some long-lived fission product nuclides discharged to the environment in fuel reprocessing wastes

    International Nuclear Information System (INIS)

    Bryant, P.M.; Jones, J.A.

    1972-12-01

    Current reprocessing practice leads to the discharge to the environment of virtually all the krypton-85 and tritium, and a large fraction of the iodine-129, formed as fission products in reactor fuel. As nuclear power programmes expand the global inventory of these long-lived nuclides is increasing. The radiological significance of these discharges is assessed in terms of radiation exposure of various population groups during the next few decades. The results of this assessment show that krypton-85 will give higher dose rates than tritium or iodine-129, but that on conventional radiological protection criteria these do not justify taking action to remove krypton-85 from reprocessing plant effluents before the 21st century. (author)

  7. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  8. Evaluation of the ability of commercial wine yeasts to form biofilms (mats) and adhere to plastic: implications for the microbiota of the winery environment.

    Science.gov (United States)

    Tek, Ee Lin; Sundstrom, Joanna F; Gardner, Jennifer M; Oliver, Stephen G; Jiranek, Vladimir

    2018-02-01

    Commercially available active dried wine yeasts are regularly used by winemakers worldwide to achieve reliable fermentations and obtain quality wine. This practice has led to increased evidence of traces of commercial wine yeast in the vineyard, winery and uninoculated musts. The mechanism(s) that enables commercial wine yeast to persist in the winery environment and the influence to native microbial communities on this persistence is poorly understood. This study has investigated the ability of commercial wine yeasts to form biofilms and adhere to plastic. The results indicate that the biofilms formed by commercial yeasts consist of cells with a combination of different lifestyles (replicative and non-replicative) and growth modes including invasive growth, bud elongation, sporulation and a mat sectoring-like phenotype. Invasive growth was greatly enhanced on grape pulp regardless of strain, while adhesion on plastic varied between strains. The findings suggest a possible mechanism that allows commercial yeast to colonise and survive in the winery environment, which may have implications for the indigenous microbiota profile as well as the population profile in uninoculated fermentations if their dissemination is not controlled. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. First Report of Microfaunal Remains from Lignitic Sequences of Bhavnagar Lignite Mine (khadsaliya Formation), Gujarat, India: Implication to Depositional Environments and Age

    Science.gov (United States)

    Maurya, A. S.

    2016-12-01

    FIRST REPORT OF MICROFAUNAL REMAINS FROM LIGNITIC SEQUENCES OF BHAVNAGAR LIGNITE MINE (KHADSALIYA FORMATION), GUJARAT, INDIA: IMPLICATION TO DEPOSITIONAL ENVIRONMENTS AND AGEABHAYANAND SINGH MAURYA1*, SANJAY KUMAR VERMA1, PRAGYA PANDEY11Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee Moderately preserved fish otoliths, fish vertebra, bivalves, pteropods, ostracods and foraminifereral remains were recovered from the grey to greenish-grey clays of Khadsaliya Formation, Bhavnagar Lignite Mine (western India) and quantitatively analyzed to understand the depositional environment. The bio-facies assemblage is diverse and dominated by fauna Fishes, Bivalve, Pteropods and with rare occurrences of Ostracoda and Foraminifera. Fish fauna includes otoliths represented by Ambassidarum, Apogonidarum, Percoideorum and Gobiidarum vastani, out of which Gobiidarum vastani is possibly representing Ypresian (early Eocene). The Globanomalina ovalis a smaller planktic foraminifer is known to be a very short ranged species corresponds to Planktic Foranimiferal Zone 5 to 6 (P5-P6) i.e late Thanetian to early Yepresian. Presence of both fresh water (Lepisosteus, Osteoglossidae), fresh water (Cypridopsis) ostracods and shallow marine fauna (Enchodus, Egertonia and Stephanodus) of fish vertebra; (Cardita) bivalve, , marine water (Globanomalina, Eggrella, Pyrulinoides) foraminifer suggests that Bhavnagar lignite mine have an assemblage of admixed fauna and rocks of Khaldsiya formation at Bhavnagar Lignite mine deposited under marine transgressive-regressive cycles. Some of the microfauna from Bhavnagar lignite mine show close affinities with microfaunal assemblages of the Vastan lignite mine of Gujarat, India which is stated to be of Ypresian (early Eocene).

  10. Uranium and Cesium sorption to bentonite colloids in high salinity and carbonate-rich environments: Implications for radionuclide transport

    Science.gov (United States)

    Tran, E. L.; Teutsch, N.; Klein-BenDavid, O.; Weisbrod, N.

    2017-12-01

    When radionuclides are leaked into the subsurface due to engineered waste disposal container failure, the ultimate barrier to migration of radionuclides into local aquifers is sorption to the surrounding rock matrix and sediments, which often includes a bentonite backfill. The extent of this sorption is dependent on pH, ionic strength, surface area availability, radionuclide concentration, surface mineral composition, and solution chemistry. Colloidal-sized bentonite particles eroded from the backfill have been shown to facilitate the transport of radionuclides sorbed to them away from their source. Thus, sorption of radionuclides such as uranium and cesium to bentonite surfaces can be both a mobilization or retardation factor. Though numerous studies have been conducted to-date on sorption of radionuclides under low ionic strength and carbonate-poor conditions, there has been little research conducted on the behavior of radionuclides in high salinities and carbonate rich conditions typical of aquifers in the vicinity of some potential nuclear repositories. This study attempts to characterize the sorption properties of U(VI) and Cs to bentonite colloids under these conditions using controlled batch experiments. Results indicated that U(VI) undergoes little to no sorption to bentonite colloids in a high-salinity (TDS= 9000 mg/L) artificial groundwater. This lack of sorption was attributed to the formation of CaUO2(CO3)22- and Ca2UO2(CO3)3 aqueous ions which stabilize the UO22+ ions in solution. In contrast, Cs exhibited greater sorption, the extent to which was influenced greatly by the matrix water's ionic strength and the colloid concentration used. Surprisingly, when both U and Cs were together, the presence of U(VI) in solution decreased Cs sorption, possibly due to the formation of stabilizing CaUO2(CO3)22- anions. The implications of this research are that rather than undergoing colloid-facilitated transport, U(VI) is expected to migrate similarly to a

  11. Depositional environments, provenance and paleoclimatic implications of Ordovician siliciclastic rocks of the Thango Formation, Spiti Valley, Tethys Himalaya, northern India

    Science.gov (United States)

    Rashid, Shaik A.; Ganai, Javid A.

    2018-05-01

    Recently published findings indicate that the Ordovician period has been much more dynamic than previously anticipated thus making this period significant in geological time. The Ordovician of India can best be studied in the Spiti region because the Spiti basin records the complete uninterrupted history of excellent marine sedimentary rocks starting from Cambrian to Paleogene which were deposited along the northern margin of India. Due to these reasons the geochemical data on the Ordovician rocks from the Spiti region is uncommon. The present geochemical study on the Ordovician Thango Formation (Sanugba Group) is mainly aimed to understand the provenance and the paleoclimatic conditions. The sandstones are the dominant lithology of the Thango Formation with intercalations of minor amount of shales. Detailed petrographic and sedimentological analysis of these rocks suggest that three major depositional environments, viz., fluvial, transitional and marine prevailed in the basin representing transgressive and regressive phases. The major and trace element ratios such as SiO2/Al2O3, K2O/Na2O and La-Th- Sc discrimination diagram suggest that these rocks were deposited in passive margin tectonic settings. Various geochemical discriminants and elemental ratios such as K2O/Na2O, Al2O3/TiO2, La/Sc, Th/Sc, Cr/Th, Zr/Sc, (Gd/Yb)N and pronounced negative Eu anomalies indicate the rocks to be the product of weathering of post-Archean granites. The striking similarities of the multi-elemental spider diagrams of the studied sediments and the Himalayan granitoids indicate that sediments are sourced from the Proterozoic orogenic belts of the Himalayan region. Chemical index of alteration (CIA) values of the studied sediments (55-72) suggest that the source rocks underwent low to moderate degree of chemical weathering. The span of the CIA values (55-72) recorded in the sediments from the Spiti region may have resulted from varying degrees of weathering conditions in the source area

  12. The Last-glacial/Interglacial Transition in northern Greece: consequences on physical environments and implications for human populations.

    Science.gov (United States)

    Chabrol, Antoine

    2010-05-01

    Across the Mediterranean Basin, the glacial-interglacial transition (15000-6000 BP) is the transition from hunter-gatherer societies of the Upper Paleolithic and Mesolithic Final companies to Neolithic farmers. In Epirus (northwestern Greece), the lack of archaeological sites is obvious for this period: only two cave sites have yielded Upper Paleolithic occupations and one open air site was dated to the Mesolithic. At the scale of the Tardiglacial and the Holocene, climate fluctuations have been multiple and caused palaeogeographic changes that we do not yet fully measure the amplitudes and limitations: significant change in the coastline and coastal paleogeography and modification of river systems. The prehistoric remains in a continental environment can not be easily found: they were either destroyed by marine erosion during the post-glacial rebound, or they were buried by sediment. The study we are conducting as part of a PhD in geoarchaeology tries to better understand the response of the physical backgrounds in northwestern Greece. Our study focuses on two specific areas: the delta formed by the river Thyamis (or Kalamas) and the inlet between the island of Corfu and the mainland. The first has never been paleoenvironmentaly studied. Likewise, archaeological researches in the watershed are almost nonexistent. The second study area is of paramount importance to understand the likely impact of the post-glacial rebound on the prehistoric and archaeological maps: initial investigations indicate that this space was occupied by a lake that has ceased to function around 10 000 BP. The paper will present preliminary results on the paleogeographic evolution of the delta Thyamis. In June 2009, combined measures of electrical resistivity, seismic refraction and GPR profiles have established the thickness of the Holocene sedimentation: nearly 15 meters at the upstream of the delta. To better understand the prehistoric and historical evolution of this space, a first serie

  13. [Variation Characteristics of Cave Water Hydrogeochemistry in Naduo Cave of Guizhou and Its Implications for Environment Research].

    Science.gov (United States)

    Shen, Wei; Wang, Jian-li; Wang, Jia-lu; Jiang, Xian-shu; Mao, Qing-ya; Chen, Zhi-qiu; Liu, Xiao

    2015-12-01

    During the period from December 2012 to December 2014, three dripping water sites (S1, S2, S3) and one pool water site (SC) have been selected for a long-term monitoring of geochemical indexes in Naduo Cave, Guanling county of Guizhou Province, China. Based on the local meteorological data, this paper analyzed the seasonal change of hydro-geochemical indicators and their feedbacks to climate events. The results indicated that the hydro-geochemical type of cave water was HCO₃⁻-Ca²⁺. Dripping water and pool water were in deposition all the year, except in the month with the maximum precipitation. There were some discrepancies of main ions' concentration among three dripping water sites due to the difference of the migration pathways and migration time. Affected by mixed water and high CO₂ concentration of cave air, the ion concentration of pool water was higher than dripping water, and there was considerable fluctuation. The geochemistry indexes of water in Naduo Cave showed extraordinary seasonal variation rules and could perfectly respond to the external climate environment. The concentration of ions was sensitive to the response of the annual precipitation change caused by extreme climate events. During the rainy season, the concentrations of Ca²⁺, Mg²⁺ and SO₄²⁻ in 2013 were relatively higher and more stable than those in 2014. The response time and susceptivity of each monitoring site were inconsistent.

  14. Microbial Diversity in Surface Iron-Rich Aqueous Environments: Implications for Seeking Signs of Life on Mars

    Science.gov (United States)

    Brown, I. I.; Allen, C. C.; Tringe, S. G.; Klatt, C. G.; Bryant, D. A.; Sarkisova, S. A.; Garrison, D. H.; McKay, D. S.

    2010-01-01

    The success of selecting future landing sites on Mars to discover extinct and/or extant extraterrestrial life is dependent on the correct approximation of available knowledge about terrestrial paleogeochemistry and life evolution to Martian (paleo) geology and geochemistry. It is well known that both Earth and Mars are Fe rich. This widespread occurrence suggests that Fe may have played a key role in early life forms, where it probably served as a key constituent in early prosthetic moieties in many proteins of ancient microbes on Earth and likely Mars. The second critical idea is the premise that Life on Mars could most likely have developed when Mars experienced tectonic activity [1] which dramatically decreased around 1 bin years after Martian creation. After that Martian life could have gone extinct or hibernated in the deep subsurface, which would be expensive to reach in contrast to the successful work of Martian surface rovers. Here we analyze the diversity of microbes in several terrestrial Fe rich surface environments in conjunction with the phylogeny and molecular timing of emergence of those microbes on Earth. Anticipated results should help evaluate future landing sites on Mars in searches for biosignatures.

  15. Long-Term Sorption of Metals Is Similar among Plastic Types: Implications for Plastic Debris in Aquatic Environments

    Science.gov (United States)

    Rochman, Chelsea M.; Hentschel, Brian T.; Teh, Swee J.

    2014-01-01

    Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types. PMID:24454866

  16. Long-term sorption of metals is similar among plastic types: implications for plastic debris in aquatic environments.

    Directory of Open Access Journals (Sweden)

    Chelsea M Rochman

    Full Text Available Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET, high-density polyethylene (HDPE, polyvinyl chloride (PVC, low-density polyethylene (LDPE, and polypropylene (PP. Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb, can be found on plastic debris composed of various plastic types.

  17. Long-term sorption of metals is similar among plastic types: implications for plastic debris in aquatic environments.

    Science.gov (United States)

    Rochman, Chelsea M; Hentschel, Brian T; Teh, Swee J

    2014-01-01

    Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types.

  18. Influx of Dissolved Silica in Shallow Marine Environments in the Early Rhaetian (Late Triassic): Implications for Timing of Supercontinental Rifting

    Science.gov (United States)

    Tackett, L.

    2017-12-01

    The Rhaetian Stage of the Late Triassic terminated with a mass extinction, but the late Norian-early Rhaetian paleoecological and geochemical transitions and their relationship to events leading up to the End-Triassic mass extinction are poorly understood. To address this issue, presented here is a multi-proxy dataset from New York Canyon, Nevada (USA) relating isotope chemostratigraphy (Sr, C, O), shallow marine benthic macrofossils, and microfossils. At this Panthalassan locality the Norian-Rhaetian boundary is characterized by a negative strontium isotope excursion that facilitates correlation with Tethyan deposits. In sedimentary horizons immediately below and above this excursion, siliceous demosponge spicules (desmids) are abundant components of the microfossil populations, and silicification of calcareous microfossils becomes common. In the sedimentary beds marking the main excursion, hexactinellid sponge spicules are abundant. These results indicate a large input of dissolved silica in shallow marine environments, while the negative strontium values are consistent with increased seafloor spreading and hydrothermal vent activity or basalt weathering, either scenario being a plausible silica source for the typically silica-limited sponges that proliferated during this interval. The biosedimentary features observed across the Norian-Rhaetian boundary are similar to those observed in the earliest Jurassic in marine sections around the world following the End-Triassic mass extinction, but no clear biotic turnover is observed across the Norian-Rhaetian boundary in this succession. Thus, biosedimentary shifts across the Norian-Rhaetian boundary may add important geochemical context to the end-Triassic mass extinction event.

  19. Quinolone co-resistance in ESBL- or AmpC-producing Escherichia coli from an Indian urban aquatic environment and their public health implications.

    Science.gov (United States)

    Bajaj, Priyanka; Kanaujia, Pawan Kumar; Singh, Nambram Somendro; Sharma, Shalu; Kumar, Shakti; Virdi, Jugsharan Singh

    2016-01-01

    Quinolone and β-lactam antibiotics constitute major mainstay of treatment against infections caused by pathogenic Escherichia coli. Presence of E. coli strains expressing co-resistance to both these antibiotic classes in urban aquatic environments which are consistently being used for various anthropogenic activities represents a serious public health concern. From a heterogeneous collection of 61 E. coli strains isolated from the river Yamuna traversing through the National Capital Territory of Delhi (India), those harboring blaCTX-M-15 (n = 10) or blaCMY-42 (n = 2) were investigated for co-resistance to quinolones and the molecular mechanisms thereof. Resistance was primarily attributed to amino acid substitutions in the quinolone resistance-determining regions (QRDRs) of GyrA (S83L ± D87N) and ParC (S80I ± E84K). One of the E. coli strains, viz., IPE, also carried substitutions in GyrB and ParE at positions Ser492→Asn and Ser458→Ala, respectively. The phenotypically susceptible strains nevertheless carried plasmid-mediated quinolone resistance (PMQR) gene, viz., qnrS, which showed co-transfer to the recipient quinolone-sensitive E. coli J53 along with the genes encoding β-lactamases and led to increase in minimal inhibitory concentrations of quinolone antibiotics. To the best of our knowledge, this represents first report of molecular characterization of quinolone co-resistance in E. coli harboring genes for ESBLs or AmpC β-lactamases from a natural aquatic environment of India. The study warrants true appreciation of the potential of urban aquatic environments in the emergence and spread of multi-drug resistance and underscores the need to characterize resistance genetic elements vis-à-vis their public health implications, irrespective of apparent phenotypic resistance.

  20. Cooperative phenomena in superconducting atom-chips

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Sebastian; Kubala, Bjoern; Ankerhold, Joachim [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

    2013-07-01

    We theoretically investigate the physics of hybrid quantum systems, where a cloud of cold atoms is coupled to superconducting microstructures, so called superconducting atom-chips. Coherent enhancement, due to the large number of atoms in the cloud, opens a path to the study of strong coupling effects, like superradiance/Dicke-physics in a decohering environment. A structured environment can be designed by embedding a Cooper pair box within the cavity. Moreover, in such a system the transfer of quantum information between the atomic cloud and the superconducting solid state system can be studied.

  1. Materials selection for long life in low earth orbit - A critical evaluation of atomic oxygen testing with thermal atom systems

    Science.gov (United States)

    Koontz, S. L.; Albyn, K.; Leger, L.

    1990-01-01

    The use of thermal atom test methods as a materials selection and screening technique for low-earth orbit (LEO) spacecraft is critically evaluated. The chemistry and physics of thermal atom environments are compared with the LEO environment. The relative reactivities of a number of materials determined in thermal atom environments are compared with those observed in LEO and in high-quality LEO simulations. Reaction efficiencies (cu cm/atom) measured in a new type of thermal atom apparatus are one-thousandth to one ten-thousandth those observed in LEO, and many materials showing nearly identical reactivities in LEO show relative reactivities differing by as much as a factor of eight in thermal atom systems. A simple phenomenological kinetic model for the reaction of oxygen atoms with organic materials can be used to explain the differences in reactivity in different environments. Certain speciic thermal atom test environments can be used as reliable materials screening tools.

  2. BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

    Science.gov (United States)

    Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

    2014-01-01

    BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

  3. Precipitation of Carbonate Minerals Induced by the Halophilic Chromohalobacter Israelensis under High Salt Concentrations: Implications for Natural Environments

    Directory of Open Access Journals (Sweden)

    Zuozhen Han

    2017-06-01

    Full Text Available The precipitation of carbonate minerals induced by halophilic bacteria has aroused wide concern. The study aimed to investigate the characterization and process of biomineralization in high salt systems by halophilic Chromohalobacter israelensis LD532 (GenBank: KX766026 bacteria, isolated from the Yinjiashan Saltern in China. Carbonate minerals were induced in magnesium sulfate and magnesium chloride medium, respectively. The mineral phase, morphology, and elemental composition of minerals were analyzed using X-ray p owder diffraction, scanning electron microscopy, and energy dispersive X-ray detection. Cells and ultrathin slices were studied using high resolution transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray detection. The carbonic anhydrase and ammonia released from LD532 bacteria increased pH of the medium and promoted the carbonate precipitation. Magnesium calcite and aragonite were induced by LD532 bacteria in magnesium chloride medium at an Mg/Ca molar ratio of 2, while Magnesium calcite and monohydrocalcite were precipitated in magnesium sulfate medium at the same Mg/Ca ratio, only monohydrocalcite were formed in both control groups. The morphologies and compositions of minerals in MgSO4 and MgCl2 solutions displayed significant differences, indicating different Mg2+ could affect physiological and biochemical activities of LD532 bacteria and thus affect the mineral deposition. Further study showed the nucleation sites were located on extracellular polymeric substances and intracellular vesicles of LD532 bacteria. This study is beneficial to the mechanism of carbonate biomineralization in natural salt environments.

  4. Aftershock communication during the Canterbury Earthquakes, New Zealand: implications for response and recovery in the built environment

    Science.gov (United States)

    Julia Becker,; Wein, Anne; Sally Potter,; Emma Doyle,; Ratliff, Jamie L.

    2015-01-01

    On 4 September 2010, a Mw7.1 earthquake occurred in Canterbury, New Zealand. Following the initial earthquake, an aftershock sequence was initiated, with the most significant aftershock being a Mw6.3 earthquake occurring on 22 February 2011. This aftershock caused severe damage to the city of Christchurch and building failures that killed 185 people. During the aftershock sequence it became evident that effective communication of aftershock information (e.g., history and forecasts) was imperative to assist with decision making during the response and recovery phases of the disaster, as well as preparedness for future aftershock events. As a consequence, a joint JCDR-USGS research project was initiated to investigate: • How aftershock information was communicated to organisations and to the public; • How people interpreted that information; • What people did in response to receiving that information; • What information people did and did not need; and • What decision-making challenges were encountered relating to aftershocks. Research was conducted by undertaking focus group meetings and interviews with a range of information providers and users, including scientists and science advisors, emergency managers and responders, engineers, communication officers, businesses, critical infrastructure operators, elected officials, and the public. The interviews and focus group meetings were recorded and transcribed, and key themes were identified. This paper focuses on the aftershock information needs for decision-making about the built environment post-earthquake, including those involved in response (e.g., for building assessment and management), recovery/reduction (e.g., the development of new building standards), and readiness (e.g. between aftershocks). The research has found that the communication of aftershock information varies with time, is contextual, and is affected by interactions among roles, by other information, and by decision objectives. A number

  5. Traditional foods and practices of Spanish-speaking Latina mothers influence the home food environment: implications for future interventions.

    Science.gov (United States)

    Evans, Alexandra; Chow, Sherman; Jennings, Rose; Dave, Jayna; Scoblick, Kathryn; Sterba, Katherine Regan; Loyo, Jennifer

    2011-07-01

    This study aimed to obtain in-depth information from low-income, Spanish-speaking Latino families with young children to guide the development of culturally appropriate nutrition interventions. Focus groups were used to assess parent's knowledge about healthful eating, the home food environment, perceived influences on children's eating habits, food purchasing practices, and commonly used strategies to promote healthful eating among their children. Thirty-four Latino parents (33 women; 27 born in Mexico; 21 food-insecure) of preschool-aged children participated in four focus group discussions conducted in Spanish by a trained moderator. The focus groups were audiotaped, transcribed, translated, and coded by independent raters. Results suggest that in general, parents were very knowledgeable about healthful eating and cited both parents and school as significant factors influencing children's eating habits; at home, most families had more traditional Mexican foods available than American foods; cost and familiarity with foods were the most influential factors affecting food purchasing; many parents had rules regarding sugar intake; and parents cited role modeling, reinforcement, and creative food preparation as ways to encourage children's healthful eating habits. Finally, parents generated ideas on how to best assist Latino families through interventions. Parents indicated that future interventions should be community based and teach skills to purchase and prepare meals that include low-cost and traditional Mexican ingredients, using hands-on activities. In addition, interventions could encourage and reinforce healthy food-related practices that Latino families bring from their native countries. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

  6. Therapeutic implications of disorders of cell death signalling: membranes, micro-environment, and eicosanoid and docosanoid metabolism.

    Science.gov (United States)

    Davidson, J; Rotondo, D; Rizzo, M T; Leaver, H A

    2012-06-01

    Disruptions of cell death signalling occur in pathological processes, such as cancer and degenerative disease. Increased knowledge of cell death signalling has opened new areas of therapeutic research, and identifying key mediators of cell death has become increasingly important. Early triggering events in cell death may provide potential therapeutic targets, whereas agents affecting later signals may be more palliative in nature. A group of primary mediators are derivatives of the highly unsaturated fatty acids (HUFAs), particularly oxygenated metabolites such as prostaglandins. HUFAs, esterified in cell membranes, act as critical signalling molecules in many pathological processes. Currently, agents affecting HUFA metabolism are widely prescribed in diseases involving disordered cell death signalling. However, partly due to rapid metabolism, their role in cell death signalling pathways is poorly characterized. Recently, HUFA-derived mediators, the resolvins/protectins and endocannabinoids, have added opportunities to target selective signals and pathways. This review will focus on the control of cell death by HUFA, eicosanoid (C20 fatty acid metabolites) and docosanoid (C22 metabolites), HUFA-derived lipid mediators, signalling elements in the micro-environment and their potential therapeutic applications. Further therapeutic approaches will involve cell and molecular biology, the multiple hit theory of disease progression and analysis of system plasticity. Advances in the cell biology of eicosanoid and docosanoid metabolism, together with structure/function analysis of HUFA-derived mediators, will be useful in developing therapeutic agents in pathologies characterized by alterations in cell death signalling. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

  7. Atomic magnetometer

    Science.gov (United States)

    Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM

    2012-07-03

    An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

  8. High Atom Number in Microsized Atom Traps

    Science.gov (United States)

    2015-12-14

    Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce

  9. Implications of Cost Effectiveness Screening Practices in a Low Natural Gas Price Environment: Case Study of a Midwestern Residential Energy Upgrade Program

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Ian M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Borgeson, Merrian Goggio [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zimring, Mark [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2013-04-12

    With the proliferation of statewide energy savings targets and other policies favorable to energy efficiency, savings from utility customer-funded energy efficiency programs could rise to offset much of annual load growth by 2025 (Barbose et al 2013). For these increased savings to occur, however, nearly all of these programs must pass screening for cost effectiveness. Some program administrators and state regulators are finding that conventional analyses, which only consider a narrow set of energy-savings related efficiency program benefits, are now resulting in some natural gas efficiency programs failing their cost-effectiveness criteria in the new low natural gas price environment. Regulators are considering whether to scale back or terminate gas portfolios in at least four states (WA, OR, ID, NM) because of cost-effectiveness concerns. Stakeholders in several regions of the country have asked LBNL to help assess alternatives to reducing the pursuit of energy savings in their regions. We address these requests by producing two working papers: one exploring cost-effectiveness screening policy implications of low to moderate natural gas prices, and a second assessing some of the values that policymakers may take into account in weighing the pros and cons of ending natural gas efficiency programs. In this policy brief, we lay out the challenges that low gas prices pose for cost effectiveness of an electric-gas efficiency program and portfolio. We then quantify options available to regulators and administrators who want to evaluate the tradeoffs among multiple policy objectives. A multi-measure, residential energy upgrade program in the Midwest is used as a lens to explore the implications of common and emerging cost-effectiveness policies in the context of low prices for natural gas. We illustrate the results across a range of cost-effectiveness screening options, including different discount rates, levels of test application, various benefit-cost tests, and the

  10. Chameleon Induced Atomic Afterglow

    CERN Document Server

    Brax, Philippe

    2010-01-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter.

  11. Chameleon induced atomic afterglow

    International Nuclear Information System (INIS)

    Brax, Philippe

    2010-09-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter. (orig.)

  12. Chameleon induced atomic afterglow

    International Nuclear Information System (INIS)

    Brax, Philippe; Burrage, Clare

    2010-01-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter.

  13. Spontaneous emission by moving atoms

    International Nuclear Information System (INIS)

    Meystre, P.; Wilkens, M.

    1994-01-01

    It is well known that spontaneous emission is not an intrinsic atomic property, but rather results from the coupling of the atom to the vacuum modes of the electromagnetic field. As such, it can be modified by tailoring the electromagnetic environment into which the atom can radiate. This was already realized by Purcell, who noted that the spontaneous emission rate can be enhanced if the atom placed inside a cavity is resonant with one of the cavity is resonant with one of the cavity modes, and by Kleppner, who discussed the opposite case of inhibited spontaneous emission. It has also been recognized that spontaneous emission need not be an irreversible process. Indeed, a system consisting of a single atom coupled to a single mode of the electromagnetic field undergoes a periodic exchange of excitation between the atom and the field. This periodic exchange remains dominant as long as the strength of the coupling between the atom and a cavity mode is itself dominant. 23 refs., 6 figs

  14. OECD studies the implications of new energy trends; Replacement of fossil fuels for electricity in industry to benefit the environment. La OCDE estudia las consecuencias de las nuevas tendencias energeticas

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    According to a recent report from the OECD which considers the implications of new energy trends for the environment, the level of energy used as a proportion of total energy consumption varies from one country to another. This reflects the different energy policies and energy availability in each country.

  15. Bremsstrahlung in atom-atom collisions

    International Nuclear Information System (INIS)

    Amus'ya, M.Y.; Kuchiev, M.Y.; Solov'ev, A.V.

    1985-01-01

    It is shown that in the collision of a fast atom with a target atom when the frequencies are on the order of the potentials or higher, there arises bremsstrahlung comparable in intensity with the bremsstrahlung emitted by an electron with the same velocity in the field of the target atom. The mechanism by which bremsstrahlung is produced in atom-atom collisions is elucidated. Results of specific calculations of the bremsstrahlung spectra are given for α particles and helium atoms colliding with xenon

  16. Atomic and Molecular Physics Program

    Science.gov (United States)

    2013-03-05

    2 3 trapped ultracold rubidium atoms Each ensemble represents a mechanical element 2mm MOT Loading Conveyor Belt Cavity Locations...coherence • Long spin coherence (T2 ~ 10 ms) • Optical initialization and readout • Solid state system • Reduced nuclear spin environment Nitrogen...quantum effects quantifying and evading measurement backaction entanglement of macroscopic object with light Route to complex quantum systems

  17. ["Get it while you can!" attitude: late industrialization and implications for work, environment, and health in Ceará State, Brazil].

    Science.gov (United States)

    Rigotto, Raquel Maria

    2007-01-01

    The present study focuses on the characteristics of late industrialization in a city in Ceará State (in the semiarid region of Northeast Brazil) and its implications for work, environment, and health in the context of industrial mobility and advanced capitalism. Using direct observation of work processes, interviews (with production managers, company presidents, workers, local authorities, and community leaders), institutional visits and secondary data analysis, eight recently built factories that manufacture chemicals, shoes, electric appliances, clothing, mechanical parts, and packaging were analyzed as to relocation, technology, organization, work relations, worker profile, environmental and occupational risks, and the impact of these factors on health and regulatory mechanisms. The lack of adequate criteria for attracting and accepting new investments, leading to a "get it while you can" attitude, the poor quality of jobs and environmental conditions, and the scale of new changes and risks in the area, like the difficulties of the public sector and society in dealing with these challenges, raise the issue of sustainability in the current development processes.

  18. Organohalogen contamination in passerine birds from three metropolises in China: Geographical variation and its implication for anthropogenic effects on urban environments

    International Nuclear Information System (INIS)

    Yu, Le-Huan; Luo, Xiao-Jun; Liu, Hong-Ying; Zeng, Yan-Hong; Zheng, Xiao-Bo; Wu, Jiang-Ping; Yu, Yun-Jiang; Mai, Bi-Xian

    2014-01-01

    Contamination of organohalogen pollutants (OHPs), including dichlorodiphenyl trichloroethane and its metabolites (DDTs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenylethane (DBDPE), hexabromocyclododecanes (HBCDs), and dechlorane plus (DP) in three metropolises of China, Beijing, Wuhan, and Guangzhou, and a reference rural site were determined using terrestrial residential passerine species as bioindicator. DDTs dominated in Wuhan whereas flame retardants dominated in Guangzhou and Beijing. No geographical variation was found for PCB levels but it exhibited different homologue profiles among different sites which could be attributed to different dietary sources of birds. Industry characteristics of the sampling location contributed to the geographical differences in the occurrence and contamination profile of OHPs. The transformation of traditional agriculture characterized contamination profiles to industry characterized profiles in Beijing and Guangzhou implicates significantly environmental concern on the flame retardants contamination in non-hot-spot regions of China. - Highlights: • Various OHPs were determined in passerine birds from three metropolises of China. • Geographical variations of OHPs levels and contamination profiles were observed. • More concern should be taken on the dominance of FRs in Chinese developed cities. • Diet source characterized by δ 13 C plays a key role in PCB pattern determination. - Geographical variations of OHPs contamination profiles indicate significant impact of industrialization and urbanization on Chinese urban environment

  19. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  20. Relativistic elementary atoms

    International Nuclear Information System (INIS)

    Mrowczynski, S.

    1989-01-01

    The physics of relativistic elementary atoms,i.e. of Coulomb bound states of elementary particles, like positronium, pionium or an atom of μ + π - , is presented. The atom lifetimes and processes, in which the atoms are produced, are discussed. The interaction of the atoms with matter is also described. A simple derivation of most results is given. 33 refs. (author)

  1. Development of the Atomic-Resolution Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Gai, Pratibha L.; Boyes, Edward D.; Yoshida, Kenta

    2016-01-01

    The development of the novel atomic-resolution environmental transmission electron microscope (atomic-resolution ETEM) for directly probing dynamic gas–solid reactions in situ at the atomic level under controlled reaction conditions consisting of gas environment and elevated temperatures is descr......The development of the novel atomic-resolution environmental transmission electron microscope (atomic-resolution ETEM) for directly probing dynamic gas–solid reactions in situ at the atomic level under controlled reaction conditions consisting of gas environment and elevated temperatures...... is used to study steels, graphene, nanowires, etc. In this chapter, the experimental setup of the microscope column and its peripherals are described....

  2. Atom lasers and nonlinear atom optics

    International Nuclear Information System (INIS)

    Deng Lu

    2000-01-01

    Two recent experimental breakthroughs in the field of atomic physics are reported: the realization of a well-collimated, widely tunable, quasi-continuous wave atom laser, and the generation of matter waves via coherent multi-wave mixing. The former is a critical step towards a continuous wave, high brightness atom laser while the latter has opened a new field of research: nonlinear atom optics

  3. Atomic weight versus atomic mass controversy

    International Nuclear Information System (INIS)

    Holden, N.E.

    1985-01-01

    A problem for the Atomic Weights Commission for the past decade has been the controversial battle over the names ''atomic weight'' and ''atomic mass''. The Commission has considered the arguments on both sides over the years and it appears that this meeting will see more of the same discussion taking place. In this paper, I review the situation and offer some alternatives

  4. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  5. Highly excited atoms

    International Nuclear Information System (INIS)

    Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

    1981-01-01

    Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before

  6. Laser-assisted atom-atom collisions

    International Nuclear Information System (INIS)

    Roussel, F.

    1984-01-01

    The basic layer-assisted atom-atom collision processes are reviewed in order to get a simpler picture of the main physical facts. The processes can be separated into two groups: optical collisions where only one atom is changing state during the collision, the other acting as a spectator atom, and radiative collisions where the states of the two atoms are changing during the collision. All the processes can be interpreted in terms of photoexcitation of the quasimolecule formed during the collisional process. (author)

  7. Scanning Probe Microscopy for Atomic-scale Silicon Device Fabrication

    Science.gov (United States)

    Simmons, Michelle

    2005-03-01

    Over the past three decades the driving force behind the expansion of the microelectronics industry has been the ability to pack ever more features onto a silicon chip, achieved by continually miniaturising the size of the individual components. However, after 2015 there is no known technological route to reduce device sizes below 10nm. In this talk we demonstrate a complete fabrication strategy towards atomic-scale device fabrication in silicon using a combination of scanning tunneling microscopy and high purity crystal growth. In particular we overcome one of the major obstacles to making functional semiconductor devices with an STM -- connecting macroscopic leads to the device once it is removed from the vacuum environment [1]. We demonstrate key steps of the fabrication process, including the ability to place individual phosphorus atoms in silicon at precise locations [2] and encapsulate them in epitaxial silicon with minimal diffusion and segregation of the dopants [3]. We present magnetoresistance data showing the cross-over from 2D to 1D transport in nano-scale quantum wires and arrays. Finally we discuss the implications of these results for the construction of more sophisticated atomic-scale devices in silicon such as a silicon based quantum computer. [1] F.J. Ruess, L. Oberbeck, M.Y. Simmons, K.E.J. Goh, A.R. Hamilton, T. Hallam, N.J. Curson and R.G. Clark, ``Fabrication of quantum wires using scanning probe microscopy'', Nano Letters 4, 1969 (2004). [2] S. R. Schofield, N. J. Curson, M. Y. Simmons, F. J. Ruess, T. Hallam, L. Oberbeck and R. G.Clark, ``Atomically precise placement of single dopants in silicon'', Physical Review Letters 91, 136104 (2003). [3] L. Oberbeck, N. J. Curson, T. Hallam, M. Y. Simmons and R.G. Clark, ``Measurement of phosphorus segregation in silicon at the atomic-scale using scanning tunneling microscopy'', Appl. Phys. Lett. 83, 1359 (2004).

  8. Environment, 1980-1993

    International Nuclear Information System (INIS)

    1994-01-01

    This document lists all sales publications of the International Atomic Energy Agency dealing with Environment issued during the period 1980-1993. It gives a short abstract and contents of these issues along with their costs in Austrian Schillings

  9. Atoms, Radiation, and Radiation Protection

    CERN Document Server

    Turner, James E

    2007-01-01

    Atoms, Radiation, and Radiation Protection offers professionals and advanced students a comprehensive coverage of the major concepts that underlie the origins and transport of ionizing radiation in matter. Understanding atomic structure and the physical mechanisms of radiation interactions is the foundation on which much of the current practice of radiological health protection is based. The work covers the detection and measurement of radiation and the statistical interpretation of the data. The procedures that are used to protect man and the environment from the potential harmful effects of

  10. Code ATOM for calculation of atomic characteristics

    International Nuclear Information System (INIS)

    Vainshtein, L.A.

    1990-01-01

    In applying atomic physics to problems of plasma diagnostics, it is necessary to determine some atomic characteristics, including energies and transition probabilities, for very many atoms and ions. Development of general codes for calculation of many types of atomic characteristics has been based on general but comparatively simple approximate methods. The program ATOM represents an attempt at effective use of such a general code. This report gives a brief description of the methods used, and the possibilities of and limitations to the code are discussed. Characteristics of the following processes can be calculated by ATOM: radiative transitions between discrete levels, radiative ionization and recombination, collisional excitation and ionization by electron impact, collisional excitation and ionization by point heavy particle (Born approximation only), dielectronic recombination, and autoionization. ATOM explores Born (for z=1) or Coulomb-Born (for z>1) approximations. In both cases exchange and normalization can be included. (N.K.)

  11. Ab Initio Study of Chemical Reactions of Cold SrF and CaF Molecules with Alkali-Metal and Alkaline-Earth-Metal Atoms: The Implications for Sympathetic Cooling.

    Science.gov (United States)

    Kosicki, Maciej Bartosz; Kędziera, Dariusz; Żuchowski, Piotr Szymon

    2017-06-01

    We investigate the energetics of the atom exchange reaction in the SrF + alkali-metal atom and CaF + alkali-metal atom systems. Such reactions are possible only for collisions of SrF and CaF with the lithium atoms, while they are energetically forbidden for other alkali-metal atoms. Specifically, we focus on SrF interacting with Li, Rb, and Sr atoms and use ab initio methods to demonstrate that the SrF + Li and SrF + Sr reactions are barrierless. We present potential energy surfaces for the interaction of the SrF molecule with the Li, Rb, and Sr atoms in their energetically lowest-lying electronic spin states. The obtained potential energy surfaces are deep and exhibit profound interaction anisotropies. We predict that the collisions of SrF molecules in the rotational or Zeeman excited states most likely have a strong inelastic character. We discuss the prospects for the sympathetic cooling of SrF and CaF molecules using ultracold alkali-metal atoms.

  12. The exhibition Lumiere d'Atomes (Atoms light)

    International Nuclear Information System (INIS)

    Foos, Jacques

    1995-01-01

    Full text: This exhibition has been conceived in order to show for everybody, whatever his scientific level, the peaceful uses of transformations (natural or made by Man) and energetic possibilities of the atomic nucleus. The key-ideas of this exhibition were-: - nuclear applications a world of high technology; - nuclear industry men as the others; - nuclear energy an energetic independence. 6 themes were proposed: 1- Atoms and radioactivity; 2- The nuclear power stations; 3- The nuclear fuel cycle; 4- Surety and environment; 5- The other uses of radioactivity; 6- The French choice: The world nuclear data. This exhibition that comprises information posters, paintings, demonstration models, films and video games, was shown for the first time in Paris in april 1991. From this time, it was shown in many regional cities, with the help of SFEN members. 'Lumiere d'Atomes' received in 1991 the SFEN prize for its information on nuclear energy. (author)

  13. High-magnetic field atomic physics

    International Nuclear Information System (INIS)

    Gay, J.C.

    1984-01-01

    This chapter discusses both the traditional developments of Zeeman techniques at strong fields and the fundamental concepts of diamagnetism. Topics considered include historical aspects, the production of high fields, the atom in a magnetic field (Hamiltonian and symmetries, the various magnetic regimes in atomic spectra), applications of the Zeeman effect at strong B fields, the Landau regime for loosely bound particles, theoretical concepts of atomic diamagnetism, and the ultra-high-field regime and quantum electrodynamics. It is concluded that the wide implications of the problem of the strongly magnetized hydrogen atom in various domains of physics and its conceptual importance concerning theoretical methods of classical and quantum mechanics justify the experimental and theoretical efforts in atomic physics

  14. Neutral atom traps.

    Energy Technology Data Exchange (ETDEWEB)

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  15. Three-atom clusters

    International Nuclear Information System (INIS)

    Pen'kov, F.M.

    1998-01-01

    The Born-Oppenheimer approximation is used to obtain an equation for the effective interaction in three atoms bound by a single electron. For low binding energies in an 'electron + atom' pair, long-range forces arise between the atoms, leading to bound states when the size of the three-atom cluster is a few tens of angstrom. A system made of alkali-metal atoms is considered as an example

  16. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

    1984-01-01

    We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

  17. Seasonality in autotrophic mesoplankton in a coastal upwelling-mud bank environment along the southwest coast of India and its ecological implications

    Science.gov (United States)

    Karnan, C.; Jyothibabu, R.; Manoj Kumar, T. M.; Balachandran, K. K.; Arunpandi, N.; Jagadeesan, L.

    2017-08-01

    Mesoplankton refers to both autotrophic and heterotrophic plankton with a body size between 200 - 20,000 μm. Here, we applied a FlowCAM to identify the autotrophs present in the mesoplankton size class in a coastal environment along the southwest coast of India (off Alappuzha, Kerala), which is characterized by intense coastal upwelling and mud bank formation during the Southwest Monsoon. 18 time series sampling (weekly/biweekly) sessions were carried out spanning over the Pre-Southwest Monsoon (April) to the Late-Southwest Monsoon (September) period in 2014. The study showed that during the Pre-Southwest Monsoon when nitrate level was relatively low in the study area, the mesoplankton community was entirely contributed by zooplankton, mostly consisting of copepods. During this time, the only autotrophic mesoplankton found in the water column, that too inconsistently, was Trichodesmium erythraeum. However, the entire scenario changed with the onset of the Southwest Monsoon due to hydrographical transformation and nutrient enrichment caused by the coastal upwelling. Especially during the Peak (July) and Late-Southwest Monsoon (August), the mesoplankton composition changed with a significant dominance of larger diatoms such as Fragilaria and Coscinodiscus. The autotrophic mesoplankton abundance was noticeably low during the Pre-Southwest Monsoon (av. 3145 ± 2396 individual m-3 and av. 2045 ± 1907 individual m-3 in M1 and M2, respectively), as compared to the Southwest Monsoon (av. 30436 ± 5983 individual m-3 and av. 32346 ± 11664 individual m-3 in M1 and M2, respectively). Similar was the seasonal trend in the autotrophic mesoplankton biomass, which increased from a low Pre-Southwest Monsoon value (av. 8.45 ± 7.1 mgC m-3and av. 4 ± 3.7 mgC m-3 in M1 and M2, respectively) to a significantly high value during the Southwest Monsoon (av. 117.04 ± 40.2mgC m-3 and av. 136.9 ± 68.1 mgC m-3 in M1 and M2, respectively). The FlowCAM analysis results also showed that

  18. Atomic and molecular manipulation

    CERN Document Server

    Mayne, Andrew J

    2011-01-01

    Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...

  19. Microfabricated Waveguide Atom Traps.

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    A nanoscale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon-atom interactions . A neutral - atom platform based on this microfabrication technology will be prealigned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano-waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.

  20. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  1. Proposed general amendments to the atomic energy control regulations

    International Nuclear Information System (INIS)

    1986-01-01

    Canada's Atomic Energy Control Act defines the powers and responsibilities of the Atomic Energy Control Board (AECB). Among these is to make regulations to control the development, application and use of atomic energy. In these proposed general amendments to the Atomic Energy Control Regulations substantial changes are proposed in the designation of the authority of AECB staff, exemptions from licensing, international safeguards, duties of licensees and atomic radiation workers, security of information, and provision for hearings. The scope of the control of atomic energy has been redefined as relating to matters of health, safety, security, international safeguards, and the protection of the environment

  2. Atomic Fuel, Understanding the Atom Series. Revised.

    Science.gov (United States)

    Hogerton, John F.

    This publication is part of the "Understanding the Atom" series. Complete sets of the series are available free to teachers, schools, and public librarians who can make them available for reference or use by groups. Among the topics discussed are: What Atomic Fuel Is; The Odyssey of Uranium; Production of Uranium; Fabrication of Reactor…

  3. Atomic Fisher information versus atomic number

    International Nuclear Information System (INIS)

    Nagy, A.; Sen, K.D.

    2006-01-01

    It is shown that the Thomas-Fermi Fisher information is negative. A slightly more sophisticated model proposed by Gaspar provides a qualitatively correct expression for the Fisher information: Gaspar's Fisher information is proportional to the two-third power of the atomic number. Accurate numerical calculations show an almost linear dependence on the atomic number

  4. Students' Perceptions of Computer-Based Learning Environments, Their Attitude towards Business Statistics, and Their Academic Achievement: Implications from a UK University

    Science.gov (United States)

    Nguyen, ThuyUyen H.; Charity, Ian; Robson, Andrew

    2016-01-01

    This study investigates students' perceptions of computer-based learning environments, their attitude towards business statistics, and their academic achievement in higher education. Guided by learning environments concepts and attitudinal theory, a theoretical model was proposed with two instruments, one for measuring the learning environment and…

  5. The potential implications of reclaimed wastewater reuse for irrigation on the agricultural environment: The knowns and unknowns of the fate of antibiotics and antibiotic resistant bacteria and resistance genes - A review.

    Science.gov (United States)

    Christou, Anastasis; Agüera, Ana; Bayona, Josep Maria; Cytryn, Eddie; Fotopoulos, Vasileios; Lambropoulou, Dimitra; Manaia, Célia M; Michael, Costas; Revitt, Mike; Schröder, Peter; Fatta-Kassinos, Despo

    2017-10-15

    The use of reclaimed wastewater (RWW) for the irrigation of crops may result in the continuous exposure of the agricultural environment to antibiotics, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). In recent years, certain evidence indicate that antibiotics and resistance genes may become disseminated in agricultural soils as a result of the amendment with manure and biosolids and irrigation with RWW. Antibiotic residues and other contaminants may undergo sorption/desorption and transformation processes (both biotic and abiotic), and have the potential to affect the soil microbiota. Antibiotics found in the soil pore water (bioavailable fraction) as a result of RWW irrigation may be taken up by crop plants, bioaccumulate within plant tissues and subsequently enter the food webs; potentially resulting in detrimental public health implications. It can be also hypothesized that ARGs can spread among soil and plant-associated bacteria, a fact that may have serious human health implications. The majority of studies dealing with these environmental and social challenges related with the use of RWW for irrigation were conducted under laboratory or using, somehow, controlled conditions. This critical review discusses the state of the art on the fate of antibiotics, ARB and ARGs in agricultural environment where RWW is applied for irrigation. The implications associated with the uptake of antibiotics by plants (uptake mechanisms) and the potential risks to public health are highlighted. Additionally, knowledge gaps as well as challenges and opportunities are addressed, with the aim of boosting future research towards an enhanced understanding of the fate and implications of these contaminants of emerging concern in the agricultural environment. These are key issues in a world where the increasing water scarcity and the continuous appeal of circular economy demand answers for a long-term safe use of RWW for irrigation. Copyright © 2017 Elsevier

  6. Atomic-fluorescence spectrophotometry

    International Nuclear Information System (INIS)

    Bakhturova, N.F.; Yudelevich, I.G.

    1975-01-01

    Atomic-fluorescence spectrophotometry, a comparatively new method for the analysis of trace quantities, has developed rapidly in the past ten years. Theoretical and experimental studies by many workers have shown that atomic-fluorescence spectrophotometry (AFS) is capable of achieving a better limit than atomic absorption for a large number of elements. The present review examines briefly the principles of atomic-fluorescence spectrophotometry and the types of fluorescent transition. The excitation sources, flame and nonflame atomizers, used in AFS are described. The limits of detection achieved up to the present, using flame and nonflame methods of atomization are given

  7. PHYSICS: Toward Atom Chips.

    Science.gov (United States)

    Fortágh, József; Zimmermann, Claus

    2005-02-11

    As a novel approach for turning the peculiar features of quantum mechanics into practical devices, researchers are investigating the use of ultracold atomic clouds above microchips. Such "atom chips" may find use as sensitive probes for gravity, acceleration, rotation, and tiny magnetic forces. In their Perspective, Fortagh and Zimmermann discuss recent advances toward creating atom chips, in which current-carrying conductors in the chips create magnetic microtraps that confine the atomic clouds. Despite some intrinsic limits to the performance of atom chips, existing technologies are capable of producing atom chips, and many possibilities for their construction remain to be explored.

  8. THE ORNL ATOM PROBE

    OpenAIRE

    Miller, M.

    1986-01-01

    The ORNL Atom Probe is a microanalytical tool for studies in materials science. The instrument is a combination of a customized version of the vacuum system of the VG FIM-100 atom probe, an ORNL-designed microcomputer-controlled digital timing system, and a double curved CEMA Imaging Atom Probe detector. The atom probe combines four instruments into one - namely a field ion microscope, an energy compensated time-of-flight mass spectrometer, an imaging atom probe, and a pulsed laser atom probe.

  9. A practice theory approach to understanding the interdependency of nursing practice and the environment: implications for nurse-led care delivery models.

    Science.gov (United States)

    Bender, Miriam; Feldman, Martha S

    2015-01-01

    Nursing has a rich knowledge base with which to develop care models that can transform the ways health is promoted and valued. However, theory linking the environment domain of the nursing metaparadigm with the real-world environments where nurses practice and patients experience their health care is tenuous. Practice theory is used to foreground the generative role of nursing practice in producing environments of care, providing the basis for a metaparadigm relational proposition explicitly linking nursing practice and environment metaparadigm domains. A theoretical and empirical focus on the significance of nursing practice dynamics in producing environments of care that promote health and healing will strengthen present and future nursing care models.

  10. A Single Atom Antenna

    International Nuclear Information System (INIS)

    Trinter, Florian; Williams, Joshua B; Weller, Miriam; Waitz, Markus; Pitzer, Martin; Voigtsberger, Jörg; Schober, Carl; Kastirke, Gregor; Müller, Christian; Goihl, Christoph; Burzynski, Phillip; Wiegandt, Florian; Wallauer, Robert; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus S; Jahnke, Till; Dörner, Reinhard; Chiang, Ying-Chih; Gokhberg, Kirill

    2015-01-01

    Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver. (paper)

  11. Deep Space Atomic Clock

    Data.gov (United States)

    National Aeronautics and Space Administration — The Deep Space Atomic Clock (DSAC) project will develop a small, low mass atomic clock based on mercury-ion trap technology and demonstrate it in space providing the...

  12. Navigation with Atom Interferometers

    Science.gov (United States)

    2017-03-20

    Navigation with Atom Interferometers Mary F. Locke and Frank A. Narducci Avionics Department Naval Air Systems Command Patuxent River, Md...20670 Abstract: In this article, we review the basic physics of an atom interferometer. We highlight the usefulness of atom interferometers for...inertial navigation due to their high phase sensitivity to both linear acceleration and angular rotation, but also the drawback that a single atom

  13. Single atom spintronics

    International Nuclear Information System (INIS)

    Sullivan, M. R.; Armstrong, J. N.; Hua, S. Z.; Chopra, H. D.

    2005-01-01

    Full text: Single atom spintronics (SASS) represents the ultimate physical limit in device miniaturization. SASS is characterized by ballistic electron transport, and is a fertile ground for exploring new phenomena. In addition to the 'stationary' (field independent) scattering centers that have a small and fixed contribution to total transmission probability of electron waves, domain walls constitute an additional and enhanced source of scattering in these magnetic quantum point contacts (QPCs), the latter being both field and spin-dependent. Through the measurement of complete hysteresis loops as a function of quantized conductance, we present definitive evidence of enhanced backscattering of electron waves by atomically sharp domain walls in QPCs formed between microfabricated thin films [1]. Since domain walls move in a magnetic field, the magnitude of spin-dependent scattering changes as the QPC is cycled along its hysteresis loop. For example, as shown in the inset in Fig. 1, from zero towards saturation in a given field direction, the resistance varies as the wall is being swept away, whereas the resistance is constant upon returning from saturation towards zero, since in this segment of the hysteresis loop no domain wall is present across the contact. The observed spin-valve like behavior is realized by control over wall width and shape anisotropy. This behavior also unmistakably sets itself apart from any mechanical artifacts; additionally, measurements made on single atom contacts provide an artifact-free environment [2]. Intuitively, it is simpler to organize the observed BMR data according to all possible transitions between different conductance plateaus, as shown by the dotted line in Fig. 1; the solid circles show experimental data for Co, which follows the predicted scheme. Requisite elements for the observation of the effect will be discussed in detail along with a review of state of research in this field. Practically, the challenge lies in making

  14. Atomic Ferris wheel beams

    OpenAIRE

    Lembessis, Vasileios E.

    2017-01-01

    We study the generation of atom vortex beams in the case where an atomic wave-packet, moving in free space, is diffracted from a properly tailored light mask with a spiral transverse profile. We show how such a diffraction scheme could lead to the production of an atomic Ferris wheel beam.

  15. Atomic Energy Control Act

    International Nuclear Information System (INIS)

    1970-01-01

    This act provides for the establishment of the Atomic Energy Control Board. The board is responsible for the control and supervision of the development, application and use of atomic energy. The board is also considered necessary to enable Canada to participate effectively in measures of international control of atomic energy

  16. Atomic Spectra Database (ASD)

    Science.gov (United States)

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  17. Atom-atom collision cascades localization

    International Nuclear Information System (INIS)

    Kirsanov, V.V.

    1980-01-01

    The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

  18. Crystallography and environment development

    International Nuclear Information System (INIS)

    Radwan, M.M.

    1992-01-01

    Crystallography, the study of atomic and molecular structure, has given detailed information about the fine-structure of the inorganic and living world-i.e. about the environment (in the widest sense of the world)-. It has contributed to geology (at the atomic level), crystal chemistry, the structure of minerals, soils and clays. In the case of the living world it has contributed to structural studies of biological molecules; proteins, nucleic acids (DNA and RNA), and polysaccharides. knowing how the atoms in a material are arranged allows to understand the relationship between atomic structure and properties of these materials. Today we are entering a new age in crystallography-the age of genetic engineering in the living world, and inorganic crystallographic engineering, where we use crystallographic information from the structures nature has given us, to begin to design and build structure of our own, of specified properties, aiming at the welfare of man and the development of his environment

  19. Cold Atom Interferometry

    International Nuclear Information System (INIS)

    Zhan Mingsheng; Li Ke; Wang Ping; Kong Lingbo; Wang Xiaorui; Li Runbing; Tu Xianhua; He Lingxiang; Wang Jin; Lu Baolong

    2007-01-01

    In this article the recent experimental works on cold atoms carried out at Wuhan Institute of Physics and Mathematics (WIPM) are reported. These include the experimental realization of Bose-Einstein condensation (BEC), different type of cold atom interferometers, and bichromatic electromagnetically-induced transparency (EIT). We have realized Bose-Einstein condensates of 87 Rb dilute atomic gases. The apparatus consists of two horizontally mounted magneto-optic-traps (MOTs) and a QUIC magnetic trap. Nearly 3x10 8 atoms were trapped in the second MOT, and up to 1.2x10 8 atoms were adiabatically transferred to the QUIC trap. A pure condensate with about 1.1x10 5 atoms at about 30 nK was achieved. We also demonstrated two type of cold atom interferometers, the Sagnac and Ramsey interference fringes were recorded with contrast of up to 37%

  20. Generation of a slow and continuous cesium atomic beam for an atomic clock

    International Nuclear Information System (INIS)

    Park, Sang Eon; Lee, Ho Seong; Shin, Eun-joo; Kwon, Taeg Yong; Yang, Sung Hoon; Cho, Hyuck

    2002-01-01

    A thermal atomic beam from a cesium oven was slowed down by use of the Hoffnagle modified white-light cooling technique. In addition, the atomic beam was collimated by use of a two-dimensional optical molasses that was installed transverse to the atomic-beam direction. The flux of the atomic beam was 2x10 10 atoms/s, an increase of a factor of 16 as a result of the collimation. The mean longitudinal velocity was ∼24.4 m/s, and the rms velocity spread of the slowed atomic beam was ∼1 m/s. Compared with other methods, we found that the Hoffnagle method is suitable for the generation of slow atomic beams to be used in an atomic clock, which requires an ultralow magnetic field environment. This atomic beam was deflected by an angle of 30 deg. by a one-dimensional optical molasses to separate it from laser light and high-velocity atoms

  1. Mass defect effects in atomic clocks

    Science.gov (United States)

    Yudin, Valeriy; Taichenachev, Alexey

    2018-03-01

    We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (the gravitational shift and motion-induced shifts such as quadratic Doppler and micromotion shifts) can be interpreted as consequences of the mass defect in quantum atomic physics, i.e. without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions.

  2. Dynamics of islamic stock market returns and exchange rate movements in the ASEAN Countries in a regime-switching environment: Implications for the islamic investors and risk hedgers

    OpenAIRE

    Mustapha, Ishaq Muhammad; Masih, Mansur

    2017-01-01

    This research is motivated by the increasing systemic relevance of Islamic finance and Islamic stock markets beyond the borders of Arabia and other Muslim majority territories. It makes the initial attempt to consider the degree to which the five Islamic stock markets in the original ASEAN-5 and their foreign exchange markets are correlated with a view to assessing the feasibility of policy initiatives to enhance ASEAN Islamic stock market integration and the implications for portfolio inve...

  3. Bread, Freedom, Social Justice: The Origins of Regime Fragility in Egypt and Syria and the Arab Spring’s Implications for the Future Operating Environment

    Science.gov (United States)

    2015-06-21

    39 Osman M. Galal, "The Nutrition Transition in Egypt: Obesity , Undernutrition and the Food Consumption Index," Public Health...Climate, and Society 6, no. 3 (July, 2014): 333 – 4. 142 Colin P. Kelley, et al., “Climate change in the Fertile Crescent and implications of the...Egypt: Obesity , Undernutrition, and the Food Consumption Index." Public Health Nutrition 5 (2002): 141-148. Gates, Robert, interview by Robert Siegel

  4. Atoms - molecules - nuclei. Vol. 1

    International Nuclear Information System (INIS)

    Otter, G.; Honecker, R.

    1993-01-01

    This first volume covers the following topics: Wave-particle dualism, classical atomic physics; the Schroedinger equation, angular momentum in quantum physics, one-electron atoms and many-electron atoms with atomic structure, atomic spectra, exotic atoms, influence of electric and magnetic fields

  5. Atomic collisions research with excited atomic species

    International Nuclear Information System (INIS)

    Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

    1999-01-01

    Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

  6. Assessing the efficacy of dredged materials from Lake Panasoffkee, Florida: implication to environment and agriculture. Part 1: Soil and environmental quality aspect.

    Science.gov (United States)

    Sigua, Gilbert C; Holtkamp, Mike L; Coleman, Samuel W

    2004-01-01

    Dredged materials because of its variable but unique physical and chemical properties are often viewed by society and regulators as pollutants, but many have used these materials in coastal nourishment, land or wetland creation, construction materials, and for soil improvement as a soil amendment. Environmental impact assessment is an important pre-requisite to many dredging initiatives. The ability to reuse lake-dredge materials (LDM) for agricultural purposes is important because it reduces the need for off-shore disposal and provides an alternative to disposal of the materials in landfills. Additional research on disposal options of dredged materials are much needed to supply information on criteria testing and evaluation of the physical and chemical impacts of dredged materials at a disposal site, as well as information on many other aspects of dredging and dredged material disposal. While preliminary efforts are underway to provide information to establish criteria for land disposal, testing procedures for possible land disposal of contaminated sediments are still in their developing stage. The objective of this study (Part 1) was to quantify the effect of applied LDM from Lake Panasoffkee (LP), Florida on soil physico-chemical properties (soil quality) at the disposal site. This series of two papers aims at providing assessment of the efficacy of lake-dredged materials from LP especially its implication to environment (soil quality, Part 1) and agriculture (forage quality and pasture establishment, Part 2). The experimental treatments that were evaluated consisted of different ratios of natural soil (NS) to LDM: LDM0 (100% NS:0% LDM); LDM25 (75% NS:25% LDM); LDM50 (50% NS:50% LDM); LDM75 (25% NS:75% LDM); and LDM100 (0% NS:100% LDM). Field layout was based on the principle of a completely randomized block design with four replications. The Mehlich 1 method (0.05 N HCl in 0.025 N H2SO4) was used for chemical extraction of soil. Soil P and other exchangeable

  7. Assessing the efficacy of dredged materials from Lake Panasoffkee, Florida: implication to environment and agriculture. Part 2: pasture establishment and forage productivity.

    Science.gov (United States)

    Sigua, Gilbert C; Holtkamp, Mike L; Coleman, Samuel W

    2004-01-01

    Current dredged material disposal alternatives have several limitations. Options for dealing with dredged materials include leaving them alone, capping them with clean sediments, placing them in confined facilities, disposing of them at upland sites, treating them chemically, or using them for wetlands creation or other beneficial uses The ability to reuse lake-dredge materials (LDM) for agricultural purposes is important because it reduces the need for offshore disposal and provides an alternative to disposal of the materials in landfills. Often these materials can be obtained at little or no cost to the farmers or landowners. Thus, forage production offers an alternative to waste management since nutrients in the LDM are recycled into crops that are not directly consumed by humans. The objective of this study (Part 2) were to: (1) assess dredge materials from Lake Panasoffkee, Florida as a soil amendment to establish bahiagrass (BG) in a subtropical beef cattle pasture in Sumter County, Florida; and (2) determine the effect of LDM application on the crude protein (CP) and nutrient uptake of BG. This series of two papers aims at providing assessment of the efficacy of lake-dredged materials especially its implication to environment (soil quality, Part 1) and agriculture (forage quality and pasture establishment, Part 2). The experimental treatments that were evaluated consisted of different ratios of natural soil (NS) to LDM: LDM0 (100% NS:0% LDM); LDM25 (75% NS:25% LDM); LDM50 (50% NS:50% LDM); LDM75 (25% NS:75% LDM); and LDM100 (0% NS:100% LDM). Bahiagrass plots at its early establishment were cut to a 5-cm stubble height on Julian days 112 and harvested to the same stubble height on Julian days 238 and on Julian days 546 following the double-ring method. Field layout was based on the principle of a completely randomized block design with four replications. Plant samples harvested at 546 Julian days were ground to pass through a 1-mm mesh screen in a Wiley mill

  8. Atomic and molecular sciences

    International Nuclear Information System (INIS)

    Lane, N.F.

    1989-01-01

    The theoretical atomic and molecular physics program at Rice University addresses basic questions about the collision dynamics of electrons, atoms, ions and molecules, emphasizing processes related to possible new energy technologies and other applications. The program focuses on inelastic collision processes that are important in understanding energy and ionization balance in disturbed gases and plasmas. Emphasis is placed on systems and processes where some experimental information is available or where theoretical results may be expected to stimulate new measurements. Examples of current projects include: excitation and charge-transfer processes; orientation and alignment of excited states following collisions; Rydberg atom collisions with atoms and molecules; Penning ionization and ion-pair formation in atom-atom collisions; electron-impact ionization in dense, high-temperature plasmas; electron-molecule collisions; and related topics

  9. Modern atomic physics

    CERN Document Server

    Natarajan, Vasant

    2015-01-01

    Much of our understanding of physics in the last 30-plus years has come from research on atoms, photons, and their interactions. Collecting information previously scattered throughout the literature, Modern Atomic Physics provides students with one unified guide to contemporary developments in the field. After reviewing metrology and preliminary material, the text explains core areas of atomic physics. Important topics discussed include the spontaneous emission of radiation, stimulated transitions and the properties of gas, the physics and applications of resonance fluorescence, coherence, cooling and trapping of charged and neutral particles, and atomic beam magnetic resonance experiments. Covering standards, a different way of looking at a photon, stimulated radiation, and frequency combs, the appendices avoid jargon and use historical notes and personal anecdotes to make the topics accessible to non-atomic physics students. Written by a leader in atomic and optical physics, this text gives a state-of-the...

  10. Atomic Power Safety

    Energy Technology Data Exchange (ETDEWEB)

    Hogerton, John F

    1964-01-01

    This booklet is condensed from a larger publication, -Background Information on Atomic Power Safety-, published in January 1964, by the .Atomic Industrial Forum. That publication and this abridgment were produced in recognition of the emergence of commercial atomic power as an important factor in our national economy, and of the resulting need for readily available information in nontechnical form on the characteristics of nuclear power plants and on the various measures taken during their design, construction, and operation for public safety.

  11. Atomic physics made clear

    International Nuclear Information System (INIS)

    Meinhold, H.

    1980-01-01

    This book is a popular introduction into the foundations of atomic physics und quantum mechanics. Starting from some phenomenological concepts Bohr's model and the construction of the periodic system regarding the shell structure of atoms are introduced. In this framework the selection rules and magnetic moments of atomic electrons are considered. Finally the wave-particle dualism is considered. In the appendix some mathematical methods are described which are useful for a deeper penetration into the considered ideas. (HSI)

  12. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  13. Atomic hydrogen reactor

    International Nuclear Information System (INIS)

    Massip de Turville, C.M.D.

    1982-01-01

    Methods are discussed of generating heat in an atomic hydrogen reactor which involve; the production of atomic hydrogen by an electrical discharge, the capture of nascent neutrons from atomic hydrogen in a number of surrounding steel alloy tubes having a high manganese content to produce 56 Mn, the irradiation of atomic hydrogen by the high energy antineutrinos from the beta decay of 56 Mn to yield nascent neutrons, and the removal of the heat generated by the capture of nascent neutrons by 55 Mn and the beta decay of 56 Mn. (U.K.)

  14. Atom dynamics in laser fields

    International Nuclear Information System (INIS)

    Jang, Su; Mi, No Gin

    2004-12-01

    This book introduces coherent dynamics of internal state, spread of atoms wave speed, semiclassical atoms density matrix such as dynamics equation in both still and moving atoms, excitation of atoms in movement by light, dipole radiating power, quantum statistical mechanics by atoms in movement, semiclassical atoms in movement, atoms in movement in the uniform magnetic field including effects of uniform magnetic field, atom cooling using laser such as Doppler cooling, atom traps using laser and mirrors, radiant heat which particles receive, and near field interactions among atoms in laser light.

  15. Microbial Diversity of Carbonate Chimneys at the Lost City Hydrothermal Field: Implications for Life-Sustaining Systems in Peridotite Seafloor Environments

    Science.gov (United States)

    Schrenk, M. O.; Cimino, P.; Kelley, D. S.; Baross, J. A.

    2002-12-01

    The Lost City Hydrothermal Field (LCHF) is a novel peridotite-hosted vent environment discovered in Dec. 2000 at 30 N near the Mid-Atlantic Ridge. This field contains multiple large (up to 60 m), carbonate chimneys venting high pH (9-10), moderate temperature (45-75 C) fluids. The LCHF is unusual in that it is located on 1.5 my-old oceanic crust, 15 km from the nearest spreading axis. Hydrothermal flow in this system is believed to be driven by exothermic serpentinization reactions involving iron-bearing minerals in the underlying seafloor. The conditions created by such reactions, which include significant quantities of dissolved methane and hydrogen, create habitats for microbial communities specifically adapted to this unusual vent environment. Ultramafic, reducing hydrothermal environments like the LCHF may be analogous to geologic settings present on the early Earth, which have been suggested to be important for the emergence of life. Additionally, the existence of hydrothermal environments far away from an active spreading center expands the range of potential life-supporting environments elsewhere in the solar system. To study the abundance and diversity of microbial communities inhabiting the environments that characterize the LCHF, carbonate chimney samples were analyzed by microscopic and molecular methods. Cell densities of between 105 and 107 cells/g were observed within various samples collected from the chimneys. Interestingly, 4-11% of the microbial population in direct contact with vent fluids fluoresced with Flavin-420, a key coenzyme involved in methanogenesis. Enrichment culturing from chimney material under aerobic and anaerobic conditions yielded microorganisms in the thermophilic and mesophilic temperature regimes in media designed for methanogenesis, methane-oxidation, and heterotrophy. PCR analysis of chimney material indicated the presence of both Archaea and Eubacteria in the carbonate samples. SSU rDNA clone libraries constructed from the

  16. Vibration spectra of single atomic nanocontacts

    International Nuclear Information System (INIS)

    Bourahla, B; Khater, A; Rafil, O; Tigrine, R

    2006-01-01

    This paper introduces a simple model for an atomic nanocontact, where its mechanical properties are analysed by calculating numerically the local spectral properties at the contact atom and the nearby atoms. The standard methodology for calculating phonon spectral densities is extended to enable the calculation of localized contact modes and local density of states (DOS). The model system considered for the nanocontact consists of two sets of triple parallel semi-infinite atomic chains joined by a single atom in between. The matching method is used, in the harmonic approximation, to calculate the local Green's functions for the irreducible set of sites that constitute the inhomogeneous nanocontact domain. The Green's functions yield the vibration spectra and the DOS for the atomic sites. These are numerically calculated for different cases of elastic hardening and softening of the nanocontact domain. The purpose is to investigate how the local dynamics respond to local changes in the elastic environment. The analysis of the spectra and of the DOS identifies characteristic features and demonstrates the central role of a core subset of these sites for the dynamics of the nanocontact. The system models a situation which may be appropriate for contact atomic force microscopy

  17. Quantum Chemical Topology: Knowledgeable atoms in peptides

    Science.gov (United States)

    Popelier, Paul L. A.

    2012-06-01

    The need to improve atomistic biomolecular force fields remains acute. Fortunately, the abundance of contemporary computing power enables an overhaul of the architecture of current force fields, which typically base their electrostatics on fixed atomic partial charges. We discuss the principles behind the electrostatics of a more realistic force field under construction, called QCTFF. At the heart of QCTFF lies the so-called topological atom, which is a malleable box, whose shape and electrostatics changes in response to a changing environment. This response is captured by a machine learning method called Kriging. Kriging directly predicts each multipole moment of a given atom (i.e. the output) from the coordinates of the nuclei surrounding this atom (i.e. the input). This procedure yields accurate interatomic electrostatic energies, which form the basis for future-proof progress in force field design.

  18. Atomic collisions under extreme conditions in space

    International Nuclear Information System (INIS)

    Itikawa, Yukikazu

    1987-01-01

    In space, atoms and molecules are often placed under the extreme conditions which are very difficult to be realized on Earth. For instance, extremely hot and dense plasmas are found in and around various stellar objects (e.g., neutron stars) on one hand and extremely cold and diffuse gases prevail in interstellar space on the other. There is so strong a magnetic field that electron clouds in atoms and molecules are distorted. The study of atomic collisions under the extreme conditions is not only helpful in understanding the astrophysical environment but also reveals new aspects of the physics of atoms and molecules. This paper is an invitation to the study. (References are not exhaustive but only provide a clue with which more details can be found.) (author)

  19. Production and detection of cold antihydrogen atoms

    CERN Multimedia

    Amoretti, M; Bonomi, G; Bouchta, A; Bowe, P; Carraro, C; Cesar, C L; Charlton, M; Collier, M; Doser, Michael; Filippini, V; Fine, K S; Fontana, A; Fujiwara, M C; Funakoshi, R; Genova, P; Hangst, J S; Hayano, R S; Holzscheiter, M H; Jørgensen, L V; Lagomarsino, V; Landua, Rolf; Landua, Rolf; Lindelöf, D; Lodi-Rizzini, E; Macri, M; Madsen, N; Manuzio, G; Marchesotti, M; Montagna, P; Pruys, H S; Regenfus, C; Riedler, P; Rochet, J; Rotondi, A; Rouleau, G; Testera, G; Van der Werf, D P; Variola, A; Watson, T L; CERN. Geneva

    2002-01-01

    A theoretical underpinning of the standard model of fundamental particles and interactions is CPT invariance, which requires that the laws of physics be invariant under the combined discrete operations of charge conjugation, parity and time reversal. Antimatter, the existence of which was predicted by Dirac, can be used to test the CPT theorem experimental investigations involving comparisons of particles with antiparticles are numerous. Cold atoms and anti-atoms, such as hydrogen and anti-hydrogen, could form the basis of a new precise test, as CPT invariance implies that they must have the same spectrum. Observations of antihydrogen in small quantities and at high energies have been reported at the European Organization for Nuclear Research (CERN) and at Fermilab, but were not suited to precision comparison measurements. Here we demonstrate the production of antihydrogen atoms at very low energy by mixing trapped antiprotons and positrons in a cryogenic environment. The neutral anti-atoms have been detected...

  20. Atom Probe Tomographic Mapping Directly Reveals the Atomic Distribution of Phosphorus in Resin Embedded Ferritin

    Science.gov (United States)

    Perea, Daniel E.; Liu, Jia; Bartrand, Jonah; Dicken, Quinten; Thevuthasan, S. Theva; Browning, Nigel D.; Evans, James E.

    2016-01-01

    Here we report the atomic-scale analysis of biological interfaces within the ferritin protein using atom probe tomography that is facilitated by an advanced specimen preparation approach. Embedding ferritin in an organic polymer resin lacking nitrogen provided chemical contrast to visualise atomic distributions and distinguish the inorganic-organic interface of the ferrihydrite mineral core and protein shell, as well as the organic-organic interface between the ferritin protein shell and embedding resin. In addition, we definitively show the atomic-scale distribution of phosphorus as being at the surface of the ferrihydrite mineral with the distribution of sodium mapped within the protein shell environment with an enhanced distribution at the mineral/protein interface. The sample preparation method is robust and can be directly extended to further enhance the study of biological, organic and inorganic nanomaterials relevant to health, energy or the environment. PMID:26924804

  1. Effects of mass defect in atomic clocks

    Science.gov (United States)

    Taichenachev, A. V.; Yudin, V. I.

    2018-01-01

    We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (such as gravitational and quadratic Doppler shifts) can be interpreted as consequences of the mass defect, i.e., without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions..

  2. Growth and nitrogen fixation of legumes at increased salinity under field conditions: implications for the use of green manures in saline environments

    NARCIS (Netherlands)

    Bruning, B.; van Logtestijn, R.S.P; Broekman, R.A.; de Vos, A.C.; Parra González, A.; Rozema, J.

    2015-01-01

    The use of legumes as green manure can potentially increase crop productivity in saline environments and thus contribute to the sustainability of agricultural systems. Here, we present results from a field experiment conducted in the Netherlands that addressed the efficiency of nitrogen (N) fixation

  3. Sulphur-binding in recent environments. II. Speciation of sulphur and iron and implications for the occurrence of organo-sulphur compounds

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Hartgers, W.A.; Lopez, J.F.; Reiss, C.; Maxwell, J.R.; Grimalt, J.O.

    1997-01-01

    Speciation of iron and sulfur species was determined for two recent sediments (La Trinitat and Lake Cisó) which were deposited in environments with a high biological productivity and sulfate-reducing activity. In sediments from calcite ponds of La Trinitat an excess of reactive iron species (iron

  4. Atomic Ferris wheel beams

    Science.gov (United States)

    Lembessis, Vasileios E.

    2017-07-01

    We study the generation of atom vortex beams in the case where a Bose-Einstein condensate, released from a trap and moving in free space, is diffracted from a properly tailored light mask with a spiral transverse profile. We show how such a diffraction scheme could lead to the production of an atomic Ferris wheel beam.

  5. Atomic Energy Control Board

    International Nuclear Information System (INIS)

    Blackman, N.S.; Gummer, W.K.

    1982-02-01

    This paper has been prepared to provide an overview of the responsibilities and activities of the Atomic Energy Control Board. It is designed to address questions that are often asked concerning the establishment of the Atomic Energy Control Board, its enabling legislation, licensing and compliance activities, federal-provincial relationships, international obligations, and communications with the public

  6. Beyond the Atom

    Science.gov (United States)

    Cox, John

    2011-08-01

    1. Introduction - the atom in the seventies; 2. The vacuum tube; 3. The new rays; 4. The new substances; 5. Disintegration; 6. A family tree; 7. Verifications and results; 8. The objective reality of molecules; 9. The new atom; Bibliography; Index.

  7. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  8. Atoms, Molecules and Radiation

    Indian Academy of Sciences (India)

    IAS Admin

    A Refresher Course in Applications of Quantum Mechanics to 'Atoms, Molecules and Radiation' will be held at the Indian Academy of Sciences, Bangalore from December 8 to 20. 2014. The Course is primarily aimed at teachers teaching quantum mechanics and/ or atomic and molecular physics at the UG / PG level.

  9. When Atoms Want

    Science.gov (United States)

    Talanquer, Vicente

    2013-01-01

    Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use…

  10. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Loos-Vollebregt, M.T.C. de.

    1980-01-01

    A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)

  11. Theoretical atomic physics

    CERN Document Server

    Friedrich, Harald

    2017-01-01

    This expanded and updated well-established textbook contains an advanced presentation of quantum mechanics adapted to the requirements of modern atomic physics. It includes topics of current interest such as semiclassical theory, chaos, atom optics and Bose-Einstein condensation in atomic gases. In order to facilitate the consolidation of the material covered, various problems are included, together with complete solutions. The emphasis on theory enables the reader to appreciate the fundamental assumptions underlying standard theoretical constructs and to embark on independent research projects. The fourth edition of Theoretical Atomic Physics contains an updated treatment of the sections involving scattering theory and near-threshold phenomena manifest in the behaviour of cold atoms (and molecules). Special attention is given to the quantization of weakly bound states just below the continuum threshold and to low-energy scattering and quantum reflection just above. Particular emphasis is laid on the fundamen...

  12. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  13. Antiprotonic-hydrogen atoms

    International Nuclear Information System (INIS)

    Batty, C.J.

    1989-07-01

    Experimental studies of antiprotonic-hydrogen atoms have recently made great progress following the commissioning of the low energy antiproton facility (LEAR) at CERN in 1983. At the same time our understanding of the atomic cascade has increased considerably through measurements of the X-ray spectra. The life history of the p-bar-p atom is considered in some detail, from the initial capture of the antiproton when stopping in hydrogen, through the atomic cascade with the emission of X-rays, to the final antiproton annihilation and production of mesons. The experiments carried out at LEAR are described and the results compared with atomic cascade calculations and predictions of strong interaction effects. (author)

  14. Atomic Covalent Functionalization of Graphene

    Science.gov (United States)

    Johns, James E.; Hersam, Mark C.

    2012-01-01

    -dimensional materials with fundamentally different electronic and physical properties. Specifically, we focus on recent studies of the addition of atomic hydrogen, fluorine, and oxygen to the basal plane of graphene. In each of these reactions a high energy, activating step initiates the process, breaking the local π structure and distorting the surrounding lattice. Scanning tunneling microscopy experiments reveal that substrate mediated interactions often dominate when the initial binding event occurs. We then compare these substrate effects with the results of theoretical studies that typically assume a vacuum environment. As the surface coverage increases, clusters often form around the initial distortion, and the stoichiometric composition of the saturated end product depends strongly on both the substrate and reactant species. In addition to these chemical and structural observations, we review how covalent modification can extend the range of physical properties that are achievable in two-dimensional materials. PMID:23030800

  15. Atomic and Molecular Manipulation of Chemical Interactions

    National Research Council Canada - National Science Library

    Ho, Wilson

    2007-01-01

    .... In effect, the goal is to carry out chemical changes by manipulating individual atoms and molecules to induce different bonding geometry and to create new interactions with their environment. These studies provide the scientific basis for the advancement of technology in catalysis, molecular electronics, optics, chemical and biological sensing, and magnetic storage.

  16. Mexico: swapping crude for atoms

    International Nuclear Information System (INIS)

    Navarro, B.

    1982-01-01

    Mexico, considered the Saudi Arabia of the Western Hemisphere because of its proven and potential petroleum reserves, has surprised the world: it has embarked on the biggest nuclear-electric program in the Third World, only to postpone it days before scheduled approval of an international bidding (on which the atomic energy industry had pinned its hopes). A graph shows Mexican supplies of electricity by source with official projections to 1990. The point of entrance of the first nuclear reactor, originally scheduled for 1982, won't come onstream until 1983; and how nuclear-generated electricity grows close to 5% of the total in 1990. The big question is, will the future President of Mexico give the green light to the atomic megaproject. And if he does, how will Mexico deal with the serious logistics problems and grave ecological implications confronting the industry worldwide. In this issue, the author and Energy Detente touch on these questions and review the nuclear power status of Mexico, as well as addressing some of its global problems. Also presented in this issue is an update of the fuel price/tax series for the Western Hemisphere countries

  17. Early establishment response of different Pinus nigra ssp. salzmanii seed sources on contrasting environments: Implications for future reforestation programs and assisted population migration.

    Science.gov (United States)

    Taïbi, K; del Campo, A D; Aguado, A; Mulet, J M

    2016-04-15

    Forest restoration constitutes an important issue within adaptive environmental management for climate change at global scale. However, effective implementation of these programs can only be achieved by revising current seed transfer guidelines, as they lack inherent spatial and temporal dynamics associated with climate change. In this sense, provenance trials may provide key information on the relative performance of different populations and/or genotypes under changing ecological conditions. This study addresses a methodological approach to evaluate early plantation performance and the consequent phenotypic plasticity and the pattern of the adaptation of different seed sources in contrasting environments. To this end, six seed sources of Salzmann pine were tested at three contrasting trial sites testing a hypothetical assisted population migration. Adaptation at each site was assessed through Joint Regression and Additive Main effect and Multiplication Interaction (AMMI) models. Most of the observed variation was attributed to the environment (above 90% for all traits), even so genotype and genotype by environment interaction (GxE) were significant. Seedlings out-planted under better site conditions did not differ in survival but in height growth. However, on sites with higher constraints, survival differed among seed sources and diameter growth was high. The adaptation analyses (AMMI) indicated that the cold-continental seed source 'Soria' performed as a generalist seed source, whereas 'Cordilleras Béticas', the southernmost seed source, was more adapted to harsh environments (frost and drought) in terms of survival. The results supported partially the hypothesis that assisted migration of seed sources makes sense within limited transfer distances, and this was reinforced by the GxE results. The present study could be valuable to address adaptive transfer of seedings in ecological restoration and to determine the suitable seed sources for reforestation programs

  18. Thoughts on Documentation of Atomic Power Technology

    International Nuclear Information System (INIS)

    Oh, Jeong Hoon; Lee, Hee Won; Song, Ki Chan

    2012-01-01

    Korean Atomic Energy Research Institute (KAERI) has accumulated a number of technology development and research outcomes, including its representative achievements such as atomic energy technology independence and the first export of atomic energy system, since it was established in 1959. With its long history of over 50 years, KAERI has produced a large amount of information and explicit knowledge such as experiment data, database, design data, report, instructions, and operation data at each stage of its research and development process as it has performed various researches since its establishment. Also, a lot of tacit knowledge has been produced both knowingly and not unknowingly based on the experience of researchers who have participated in many projects. However, in the research environment in Korea where they focus overly on the output, tacit knowledge has not been managed properly compared to explicit knowledge. This tacit knowledge is as an important asset as explicit knowledge for an effective research and development. Moreover, as the first generation of atomic energy independence and research manpower retire, their accumulated experience and knowledge are in danger of disappearing. Therefore, in this study, we sought how to take a whole view and to document atomic energy technology researched and developed by KAERI, from the background to achievement of each field of the technology. Comprehensive and systematic documentation of atomic energy technology will establish a comprehensive management system of national atomic energy technology record to make a foundation of technical advancement and development of atomic energy technology. Also, it is expected to be used as an important knowledge and information resource of atomic energy knowledge management system

  19. Thoughts on Documentation of Atomic Power Technology

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jeong Hoon; Lee, Hee Won; Song, Ki Chan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Korean Atomic Energy Research Institute (KAERI) has accumulated a number of technology development and research outcomes, including its representative achievements such as atomic energy technology independence and the first export of atomic energy system, since it was established in 1959. With its long history of over 50 years, KAERI has produced a large amount of information and explicit knowledge such as experiment data, database, design data, report, instructions, and operation data at each stage of its research and development process as it has performed various researches since its establishment. Also, a lot of tacit knowledge has been produced both knowingly and not unknowingly based on the experience of researchers who have participated in many projects. However, in the research environment in Korea where they focus overly on the output, tacit knowledge has not been managed properly compared to explicit knowledge. This tacit knowledge is as an important asset as explicit knowledge for an effective research and development. Moreover, as the first generation of atomic energy independence and research manpower retire, their accumulated experience and knowledge are in danger of disappearing. Therefore, in this study, we sought how to take a whole view and to document atomic energy technology researched and developed by KAERI, from the background to achievement of each field of the technology. Comprehensive and systematic documentation of atomic energy technology will establish a comprehensive management system of national atomic energy technology record to make a foundation of technical advancement and development of atomic energy technology. Also, it is expected to be used as an important knowledge and information resource of atomic energy knowledge management system

  20. Subglacial hydrothermal alteration minerals in Jökulhlaup deposits of Southern Iceland, with implications for detecting past or present habitable environments on Mars.

    Science.gov (United States)

    Warner, Nicholas H; Farmer, Jack D

    2010-06-01

    Jökulhlaups are terrestrial catastrophic outfloods, often triggered by subglacial volcanic eruptions. Similar volcano-ice interactions were likely important on Mars where magma/lava may have interacted with the planet's cryosphere to produce catastrophic floods. As a potential analogue to sediments deposited during martian floods, the Holocene sandurs of Iceland are dominated by basaltic clasts derived from the subglacial environment and deposited during jökulhlaups. Palagonite tuffs and breccias, present within the deposits, represent the primary alteration lithology. The surface abundance of palagonite on the sandurs is 1-20%. X-ray diffraction (XRD) analysis of palagonite breccias confirms a mineral assemblage of zeolites, smectites, low-quartz, and kaolinite. Oriented powder X-ray diffractograms (temperature (100-140 degrees C) hydrothermal alteration of basaltic material within the subglacial environment. These results suggest that potential martian analog sites that contain a similar suite of hydrated minerals may be indicative of past hydrothermal activity and locations where past habitable environments for microbial life may be found.

  1. Experimental atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The experimental atomic physics program within the physics division is carried out by two groups, whose reports are given in this section. Work of the accelerator atomic physics group is centered around the 6.5-MV EN tandem accelerator; consequently, most of its research is concerned with atomic processes occurring to, or initiated by, few MeV/amu heavy ions. Other activities of this group include higher energy experiments at the Holifield Heavy Ion Research Facility (HHIRF), studies of electron and positron channeling radiation, and collaborative experiments at other institutions. The second experimental group concerns itself with lower energy atomic collision physics in support of the Fusion Energy Program. During the past year, the new Electron Cyclotron Resonance Source has been completed and some of the first data from this facility is presented. In addition to these two activities in experimental atomic physics, other chapters of this report describe progress in theoretical atomic physics, experimental plasma diagnostic development, and atomic data center compilation activities

  2. Atomic Structure Theory Lectures on Atomic Physics

    CERN Document Server

    Johnson, Walter R

    2007-01-01

    Atomic Structure Theory is a textbook for students with a background in quantum mechanics. The text is designed to give hands-on experience with atomic structure calculations. Material covered includes angular momentum methods, the central field Schrödinger and Dirac equations, Hartree-Fock and Dirac-Hartree-Fock equations, multiplet structure, hyperfine structure, the isotope shift, dipole and multipole transitions, basic many-body perturbation theory, configuration interaction, and correlation corrections to matrix elements. Numerical methods for solving the Schrödinger and Dirac eigenvalue problems and the (Dirac)-Hartree-Fock equations are given as well. B-spline basis sets are used to carry out sums arising in higher-order many-body calculations. Illustrative problems are provided, together with solutions. FORTRAN programs implementing the numerical methods in the text are included.

  3. Observation of dynamic atom-atom correlation in liquid helium in real space.

    Science.gov (United States)

    Dmowski, W; Diallo, S O; Lokshin, K; Ehlers, G; Ferré, G; Boronat, J; Egami, T

    2017-05-04

    Liquid 4 He becomes superfluid and flows without resistance below temperature 2.17 K. Superfluidity has been a subject of intense studies and notable advances were made in elucidating the phenomenon by experiment and theory. Nevertheless, details of the microscopic state, including dynamic atom-atom correlations in the superfluid state, are not fully understood. Here using a technique of neutron dynamic pair-density function (DPDF) analysis we show that 4 He atoms in the Bose-Einstein condensate have environment significantly different from uncondensed atoms, with the interatomic distance larger than the average by about 10%, whereas the average structure changes little through the superfluid transition. DPDF peak not seen in the snap-shot pair-density function is found at 2.3 Å, and is interpreted in terms of atomic tunnelling. The real space picture of dynamic atom-atom correlations presented here reveal characteristics of atomic dynamics not recognized so far, compelling yet another look at the phenomenon.

  4. Division of atomic physics

    International Nuclear Information System (INIS)

    Kroell, S.

    1994-01-01

    The Division of Atomic Physics, Lund Institute of Technology (LTH), is responsible for the basic physics teaching in all subjects at LTH and for specialized teaching in Optics, Atomic Physics, Atomic and Molecular Spectroscopy and Laser Physics. The Division has research activities in basic and applied optical spectroscopy, to a large extent based on lasers. It is also part of the Physics Department, Lund University, where it forms one of eight divisions. Since the beginning of 1980 the research activities of our division have been centred around the use of lasers. The activities during the period 1991-1992 is described in this progress reports

  5. Atomic mass spectrometry

    International Nuclear Information System (INIS)

    Sanz-Medel, A.

    1997-01-01

    The elemental inorganic analysis seems to be dominated today by techniques based on atomic spectrometry. After an evaluation of advantages and limitations of using mass analysers (ion detectors) versus conventional photomultipliers (photon detector) a brief review of the more popular techniques of the emerging Atomic Mass spectrometry is carried out. Their huge potential for inorganic trace analysis is such that in the future we could well witness how this end of the century and millennium marked the fall of the photons empire in Analytical Atomic Spectrometry. (Author)

  6. Atom trap trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O' Connor, T. P.; Young, L.

    2000-05-25

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

  7. Physics of the atom

    CERN Document Server

    Wehr, Russell M; Adair, Thomas W

    1984-01-01

    The fourth edition of Physics of the Atom is designed to meet the modern need for a better understanding of the atomic age. It is an introduction suitable for students with a background in university physics and mathematical competence at the level of calculus. This book is designed to be an extension of the introductory university physics course into the realm of atomic physics. It should give students a proficiency in this field comparable to their proficiency in mechanics, heat, sound, light, and electricity.

  8. Section of Atomic Collisions

    International Nuclear Information System (INIS)

    Berenyi, D.; Biri, S.; Gulyas, L.; Juhasz, Z.; Kover, A.; Orban, A.; Palinkas, J.; Papp, T.; Racz, R.; Ricz, S.

    2009-01-01

    The Section of Atomic Collisions is a research unit with extended activity in the field of atomic and molecular physics. Starting from the study of atomic processes at the beamlines of nuclear physics accelerators in the seventies, our research community became one of the centers of fundamental research in Atomki. We also have a strong connection to materials sciences especially along the line of electron and ion spectroscopy methods. Our present activity covers a wide range of topics from atomic collision mechanisms of fundamental interest, to the complex interactions of electrons, ions, photons and antiparticles with atoms, molecules, surfaces, and specific nanostructures. In the last few years, an increasing fraction of our present topics has become relevant for applications, e.g., molecular collision studies for the radiation therapy methods of tumors, or ion-nanostructure interactions for the future construction of small ion-focusing elements. Our section belongs to the Division of Atomic Physics. The other unit of the Division is the Section of Electron Spectroscopy and Materials Sciences. There are traditionally good connections and a strong collaboration between the groups of the two sections in many fields. From the very beginning of our research work in atomic collisions, external collaborations were of vital importance for us. We regularly organize international workshops in the field of fast ion-atom collisions and related small conferences in Debrecen from 1981. Recently, we organized the Conference on Radiation Damage in Biomolecular Systems (RADAM 2008, Debrecen), and coorganized the Conference on Elementary Processes in Atomic Systems (CEPAS 2008, Cluj). We have access to several large scale facilities in Europe within the framework of formal and informal collaborations. The next themes are in this article: Forward electron emission from energetic atomic collisions; Positron-atom collisions; Photon-atom interactions; Interference effects in electron

  9. Association of neighbourhood residence and preferences with the built environment, work-related travel behaviours, and health implications for employed adults: findings from the URBAN study.

    Science.gov (United States)

    Badland, Hannah M; Oliver, Melody; Kearns, Robin A; Mavoa, Suzanne; Witten, Karen; Duncan, Mitch J; Batty, G David

    2012-10-01

    Although the neighbourhoods and health field is well established, the relationships between neighbourhood selection, neighbourhood preference, work-related travel behaviours, and transport infrastructure have not been fully explored. It is likely that understanding these complex relationships more fully will inform urban policy development, and planning for neighbourhoods that support health behaviours. Accordingly, the objective of this study was to identify associations between these variables in a sample of employed adults. Self-reported demographic, work-related transport behaviours, and neighbourhood preference data were collected from 1616 employed adults recruited from 48 neighbourhoods located across four New Zealand cities. Data were collected between April 2008 and September 2010. Neighbourhood built environment measures were generated using geographical information systems. Findings demonstrated that more people preferred to live in urban (more walkable), rather than suburban (less walkable) settings. Those living in more suburban neighbourhoods had significantly longer work commute distances and lower density of public transport stops available within the neighbourhood when compared with those who lived in more urban neighbourhoods. Those preferring a suburban style neighbourhood commuted approximately 1.5 km further to work when compared with participants preferring urban settings. Respondents who preferred a suburban style neighbourhood were less likely to take public or active transport to/from work when compared with those who preferred an urban style setting, regardless of the neighbourhood type in which they resided. Although it is unlikely that constructing more walkable environments will result in work-related travel behaviour change for all, providing additional highly walkable environments will help satisfy the demand for these settings, reinforce positive health behaviours, and support those amenable to change to engage in higher levels of

  10. Effects of wood anisotropy on Teredo naval is attack and its implications for in -situ preservation of archaeological wood in the marine environment

    DEFF Research Database (Denmark)

    Eriksen, Anne Marie; Lynnerup, Niels; Villa, Chiara

    2014-01-01

    materials has become more widespread since the UNESCO Convention on the Protection of the Underwater Cultural Heritage and the Valletta Treaty. Therefore, there is a need to understand the attack rate of T. navalis taking the anisotropy of wood into consideration, primarily because in the past ship building......When exposed on the seabed, waterlogged archaeological wood in the marine environment can be subjected to degradation by Teredo navalis (commonly known as shipworm). The degradation is swift and devastating as the artefact can disappear within months. In-situ preservation of archaeological...

  11. Origins of Cell-to-Cell Bioprocessing Diversity and Implications of the Extracellular Environment Revealed at the Single-Cell Level.

    Science.gov (United States)

    Vasdekis, A E; Silverman, A M; Stephanopoulos, G

    2015-12-14

    Bioprocess limitations imposed by microbial cell-to-cell phenotypic diversity remain poorly understood. To address this, we investigated the origins of such culture diversity during lipid production and assessed the impact of the fermentation microenvironment. We measured the single-cell lipid production dynamics in a time-invariant microfluidic environment and discovered that production is not monotonic, but rather sporadic with time. To characterize this, we introduce bioprocessing noise and identify its epigenetic origins. We linked such intracellular production fluctuations with cell-to-cell productivity diversity in culture. This unmasked the phenotypic diversity amplification by the culture microenvironment, a critical parameter in strain engineering as well as metabolic disease treatment.

  12. Green environment and incident depression in South Africa: a geospatial analysis and mental health implications in a resource-limited setting.

    Science.gov (United States)

    Tomita, Andrew; Vandormael, Alain M; Cuadros, Diego; Di Minin, Enrico; Heikinheimo, Vuokko; Tanser, Frank; Slotow, Rob; Burns, Jonathan K

    2017-07-01

    Unprecedented levels of habitat transformation and rapid urbanisation are changing the way individuals interrelate with the natural environment in developing countries with high economic disparities. Although the potential benefit of green environments for mental health has been recognised, population-level evidence to this effect is scarce. We investigated the effect of green living environment in potentially countering incident depression in a nationally representative survey in South Africa. We used panel data from the South African National Income Dynamics Study (SA-NIDS). Our study used SA-NIDS data from three waves: wave 1 (2008), wave 2 (2010), and wave 3 (2012). Households were sampled on the basis of a stratified two-stage cluster design. In the first stage, 400 primary sampling units were selected for inclusion. In the second stage, two clusters of 12 dwelling units each were drawn from within each primary sampling unit (or 24 dwelling units per unit). Household and individual adult questionnaires were administered to participants. The main outcome, incident depression (ie, incident cohort of 11 156 study participants without significant depression symptoms at their first entry into SA-NIDS), was assessed in the adult survey via a ten item version of the Center for Epidemiologic Studies Depression Scale; a total score of ten or higher was used as a cutoff to indicate significant depressive symptoms. Each participant was assigned a value for green living space via a satellite-derived normalised difference vegetation index (NDVI) based on the GPS coordinates of their household location. Overall, we found uneven benefit of NDVI on incident depression among our study participants. Although the green living environment showed limited benefit across the study population as a whole, our final analysis based on logistic regression models showed that higher NDVI was a predictor of lower incident depression among middle-income compared with low-income participants

  13. Atomic Energy Authority Bill

    International Nuclear Information System (INIS)

    Gray, J.H.N.; Stoddart, D.L.; Sinclair, R.M.; Ezra, D.

    1985-01-01

    The House, in Committee, discussed the following matters in relation to the Atomic Energy Authority Bill; financing; trading; personnel conditions of employment; public relations; organization; research programmes; fuels; energy sources; information dissemination. (U.K.)

  14. Atomic Interferometry, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Vertical cavity surface emitting lasers (VCSELs) is a new technology which can be used for developing high performance laser components for atom-based sensors...

  15. Atomic bomb cataracts

    International Nuclear Information System (INIS)

    Shiraeda, Kanji

    1992-01-01

    Eye disturbance caused by atomic bomb radiation can be divided into three groups: direct injury immediately after exposure, eye lesions associated with radiation syndrome, and delayed disturbance. The crystalline lens of the eye is the most radiosensitive. Atomic bomb cataract has been investigated in a number of studies. The first section of this chapter discusses radiation cataract in terms of the incidence and characteristics. The second section deals with atomic bomb cataract, which can be diagnosed based on the four criteria: (1) opacity of the crystalline lens, (2) a history of proximal exposure, (3) lack of eye disease complicating cataract, and (4) non-exposure to radiation other than atomic bombing. The prevalence of cataract and severity of opacity are found to correlate with exposure doses and age at the time of exposure. Furthermore, it is found to correlate with distance from the hypocenter, the condition of shielding, epilation, and the presence or absence or degree of radiation syndrome. (N.K.)

  16. Topics in atomic physics

    CERN Document Server

    Burkhardt, Charles E

    2006-01-01

    The study of atomic physics propelled us into the quantum age in the early twentieth century and carried us into the twenty-first century with a wealth of new and, in some cases, unexplained phenomena. Topics in Atomic Physics provides a foundation for students to begin research in modern atomic physics. It can also serve as a reference because it contains material that is not easily located in other sources. A distinguishing feature is the thorough exposition of the quantum mechanical hydrogen atom using both the traditional formulation and an alternative treatment not usually found in textbooks. The alternative treatment exploits the preeminent nature of the pure Coulomb potential and places the Lenz vector operator on an equal footing with other operators corresponding to classically conserved quantities. A number of difficult to find proofs and derivations are included as is development of operator formalism that permits facile solution of the Stark effect in hydrogen. Discussion of the classical hydrogen...

  17. Atoms at work

    International Nuclear Information System (INIS)

    1982-07-01

    This illustrated booklet discusses the following: atoms; fission of uranium; nuclear power plants; reactor types; plutonium (formation, properties, uses); radioactive waste (fuel cycle, reprocessing, waste management); nuclear fusion; fusion reactors; radiation; radioisotopes and their uses. (U.K.)

  18. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1998-01-01

    This volume continues the series'' cutting-edge reviews on developments in this field. Since its invention in the 1920s, electrostatic precipitation has been extensively used in industrial hygiene to remove dust and particulate matter from gases before entering the atmosphere. This combination of electrostatic precipitation is reported upon in the first chapter. Following this, chapter two reviews recent advances in the area of chemical modification in electrothermal atomization. Chapter three consists of a review which deal with advances and uses of electrothermal atomization atomic absorption spectrometry. Flow injection atomic spectroscopy has developed rapidly in recent years and after a general introduction, various aspects of this technique are looked at in chapter four. Finally, in chapter five the use of various spectrometric techniques for the determination of mercury are described.

  19. Atomic and Molecular Interactions

    International Nuclear Information System (INIS)

    2002-01-01

    The Gordon Research Conference (GRC) on Atomic and Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field

  20. The Atomic Energy Control Board

    International Nuclear Information System (INIS)

    Doern, G.B.

    1976-01-01

    This study describes and assesses the regulatory and administrative processes and procedures of the Atomic Energy Control Board, the AECB. The Atomic Energy Control Act authorized the AECB to control atomic energy materials and equipment in the national interest and to participate in measures for the international control of atomic energy. The AECB is authorized to make regulations to control atomic energy materials and equipment and to make grants in support of atomic energy research. (author)

  1. Relationships between sucretolerance and salinotolerance in bacteria from hypersaline environments and their implications for the exploration of Mars and the icy worlds

    Science.gov (United States)

    Fredsgaard, Casper; Moore, Donald B.; Al Soudi, Amer F.; Crisler, James D.; Chen, Fei; Clark, Benton C.; Schneegurt, Mark A.

    2017-04-01

    The most extremely osmotolerant microbial isolates are fungi from high-sugar environments that tolerate the lowest water activity (0.61) for growth yet reported. Studies of osmotolerant bacteria have focused on halotolerance rather than sucretolerance (ability to grow in high sugar concentrations). A collection of salinotolerant (>=10% NaCl or >=50% MgSO4) bacterial isolates from the Great Salt Plains of Oklahoma and Hot Lake in Washington were screened for sucretolerance in medium supplemented with >=50% fructose, glucose or sucrose. Tolerances significantly differed between solutes, even though water activities for saline media (0.92 and 0.85 for 10 and 20% NaCl Salt Plains media, respectively) were comparable or lower than water activities for high-sugar media (0.93 and 0.90 for 50 and 70% sucrose artificial nectar media, respectively). These specific solute effects were differentially expressed among individual isolates. Extrapolating the results of earlier food science studies with yeasts at high sugar concentrations to bacteria in salty environments with low water activity should be done with caution. Furthermore, the discussion of habitable Special Regions on Mars and the icy worlds should reflect an understanding of specific solute effects.

  2. Geochemical and biomarker characteristics of crude oils and source rock hydrocarbon extracts: An implication to their correlation, depositional environment and maturation in the Northern Western Desert, Egypt

    Directory of Open Access Journals (Sweden)

    Mohamed M. El Nady

    2016-06-01

    Full Text Available Oil–oil and oil–source rock correlations are used in this study in order to achieve their relationship, depositional environments and diagenetic processes in the source rocks. Three oil samples and source rock hydrocarbon extracts were analyzed using relative geochemical analyses, and gas chromatography–mass spectrometry are used for this purpose. The results revealed that the extracts of the Alam El Bueib and Khatatba formations are derived from mixed organic sources in which terrestrial dominates marine sources, and deposited in transitional environments under less anoxic conditions. The extracts of Bahariya formation are derived from mixed marine inputs with a limited terrestrial contribution. The Alam El Bueib oil shows more contribution of terrestrial than marine sources. Also, a genetic close relation between them supported the indigenous mixed source of Alam El Bueib oil which related to different sources including the Khatatba, Alam El Bueib and Bahariya formations. Accordingly, the Alam El Bueib formation can be considered as an important source for petroleum generation in the Northern Western Desert.

  3. NIAID, NIEHS, NHLBI, and MCAN Workshop Report: The indoor environment and childhood asthma-implications for home environmental intervention in asthma prevention and management.

    Science.gov (United States)

    Gold, Diane R; Adamkiewicz, Gary; Arshad, Syed Hasan; Celedón, Juan C; Chapman, Martin D; Chew, Ginger L; Cook, Donald N; Custovic, Adnan; Gehring, Ulrike; Gern, James E; Johnson, Christine C; Kennedy, Suzanne; Koutrakis, Petros; Leaderer, Brian; Mitchell, Herman; Litonjua, Augusto A; Mueller, Geoffrey A; O'Connor, George T; Ownby, Dennis; Phipatanakul, Wanda; Persky, Victoria; Perzanowski, Matthew S; Ramsey, Clare D; Salo, Päivi M; Schwaninger, Julie M; Sordillo, Joanne E; Spira, Avrum; Suglia, Shakira F; Togias, Alkis; Zeldin, Darryl C; Matsui, Elizabeth C

    2017-10-01

    Environmental exposures have been recognized as critical in the initiation and exacerbation of asthma, one of the most common chronic childhood diseases. The National Institute of Allergy and Infectious Diseases; National Institute of Environmental Health Sciences; National Heart, Lung, and Blood Institute; and Merck Childhood Asthma Network sponsored a joint workshop to discuss the current state of science with respect to the indoor environment and its effects on the development and morbidity of childhood asthma. The workshop included US and international experts with backgrounds in allergy/allergens, immunology, asthma, environmental health, environmental exposures and pollutants, epidemiology, public health, and bioinformatics. Workshop participants provided new insights into the biologic properties of indoor exposures, indoor exposure assessment, and exposure reduction techniques. This informed a primary focus of the workshop: to critically review trials and research relevant to the prevention or control of asthma through environmental intervention. The participants identified important limitations and gaps in scientific methodologies and knowledge and proposed and prioritized areas for future research. The group reviewed socioeconomic and structural challenges to changing environmental exposure and offered recommendations for creative study design to overcome these challenges in trials to improve asthma management. The recommendations of this workshop can serve as guidance for future research in the study of the indoor environment and on environmental interventions as they pertain to the prevention and management of asthma and airway allergies. Published by Elsevier Inc.

  4. Optical atomic phase reference and timing.

    Science.gov (United States)

    Hollberg, L; Cornell, E H; Abdelrahmann, A

    2017-08-06

    Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10 -20 As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, Δ Φ / Φ total  ≤ 10 -20 , that could make an important impact in gravity wave science.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).

  5. Optical atomic phase reference and timing

    Science.gov (United States)

    Hollberg, L.; Cornell, E. H.; Abdelrahmann, A.

    2017-06-01

    Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10-20. As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, ΔΦ/Φtotal ≤ 10-20, that could make an important impact in gravity wave science. This article is part of the themed issue 'Quantum technology for the 21st century'.

  6. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  7. Harnessing the atom

    International Nuclear Information System (INIS)

    1999-01-01

    Splitting the atom has had a major impact on the history of the latter part of the 20th century. This film depicts the many benefits - and also drawbacks - of nuclear technology, and describes how the International Atomic Energy Agency performs its various tasks. It touches on challenges such as the choice between major energy sources, growing concerns about the global climate, and prospects for nuclear arms control and disarmament

  8. Optical atomic magnetometer

    Science.gov (United States)

    Budker, Dmitry; Higbie, James; Corsini, Eric P

    2013-11-19

    An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

  9. Atom probe crystallography

    OpenAIRE

    Gault, Baptiste; Moody, Michael P.; Cairney, Julie M.; Ringer, Simon P.

    2012-01-01

    This review addresses new developments in the emerging area of “atom probe crystallography”, a materials characterization tool with the unique capacity to reveal both composition and crystallographic structure at the atomic scale. This information is crucial for the manipulation of microstructure for the design of both structural and functional materials with optimized mechanical, electric, optoelectronic, magnetic, or superconducting properties that will find application in, for example, nan...

  10. Atomic Energy Act 1946

    International Nuclear Information System (INIS)

    1946-01-01

    This Act provides for the development of atomic energy in the United Kingdom and for its control. It details the duties and powers of the competent Minister, in particular his powers to obtain information on and to inspect materials, plant and processes, to control production and use of atomic energy and publication of information thereon. Also specified is the power to search for and work minerals and to acquire property. (NEA) [fr

  11. Hirshfeld atom refinement.

    Science.gov (United States)

    Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

    2014-09-01

    Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  12. On the bosonic atoms

    Science.gov (United States)

    Amusia, M. Ya.; Chernysheva, L. V.

    2018-01-01

    We investigate ground state properties of atoms, in which substitute fermions - electrons by bosons, namely π --mesons. We perform some calculations in the frame of modified Hartree-Fock (HF) equation. The modification takes into account symmetry, instead of anti-symmetry of the pair identical bosons wave function. The modified HF approach thus enhances (doubles) the effect of self-action for the boson case. Therefore, we accordingly modify the HF equations by eliminating the self-action terms "by hand". The contribution of meson-meson and meson-nucleon non-Coulomb interaction is inessential at least for atoms with low and intermediate nuclear charge, which is our main subject. We found that the binding energy of pion negative ions A π - , pion atoms A π , and the number of extra bound pions ΔN π increases with the growth of nuclear charge Z. For e.g. Xe ΔN π = 4. As an example of a simple process with a pion atom, we consider photoionization that differs essentially from that for electron atoms. Namely, it is not monotonic decreasing from the threshold but has instead a prominent maximum above threshold. We study also elastic scattering of pions by pion atoms.

  13. Atomic bomb and leukemia

    International Nuclear Information System (INIS)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T.

    1991-01-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5∼0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author)

  14. FAO and atomic energy

    International Nuclear Information System (INIS)

    1960-01-01

    During the past six years FAO has become more engaged in work concerned with atomic energy. In 1957 it established an Atomic Energy Branch. The new forces and new tools which have become available for use in the fight against poverty, disease and malnutrition can be of the greatest assistance in FAO's work in nearly all phases of the production, storage and distribution of food and other agricultural products. The Organization promotes their use to improve the standards of feeding, clothing and housing throughout the world. Another side of work related to atomic energy is concerned with combating contamination from the use of atomic energy for power production and other purposes. This raises considerable problems for food and agriculture, so that FAO also has a responsibility for assisting Governments in safeguarding their food and food-producing resources from contamination. FAO is essentially concerned with fostering wider knowledge of the many contributions that atomic science can make to agriculture, forestry, fisheries and nutrition. It is also concerned in assisting governments to establish sound programmes for applying atomic science in food and agriculture. One way of spreading such knowledge is through the publication of documents and reports

  15. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T. (Nagasaki Univ. (Japan). School of Medicine)

    1991-12-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5{approx}0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author).

  16. Maternal obesity mediated predisposition to respiratory complications at birth and in later life: understanding the implications of the obesogenic intrauterine environment.

    Science.gov (United States)

    McGillick, Erin V; Lock, Mitchell C; Orgeig, Sandra; Morrison, Janna L

    2017-01-01

    More women than not are entering pregnancy either overweight or obese. This presents a significant health care burden with respect to maternal morbidities and offspring complications at birth and in later life. In recent years it has also become clear that maternal obesity is an even greater global health problem than anticipated, because the effects are not limited to the mother but are also programmed in the fetus, known as the 'intergenerational cycle of obestiy'. Despite a large body of epidemiological evidence reporting outcomes of obese pregnancies, including offspring respiratory complications, much less is known about the molecular effects of maternal obesity on fetal lung development. This review focuses on the influence of altered substrate supply associated with the obesogenic intrauterine environment on fetal lung development. Understanding the molecular mechanisms contributing to altered fetal lung development will lead to improved respiratory outcomes for offspring at birth and in later life. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Seawater quality assessment and identification of pollution sources along the central coastal area of Gabes Gulf (SE Tunisia): Evidence of industrial impact and implications for marine environment protection.

    Science.gov (United States)

    El Zrelli, Radhouan; Rabaoui, Lotfi; Ben Alaya, Mohsen; Daghbouj, Nabil; Castet, Sylvie; Besson, Philippe; Michel, Sylvain; Bejaoui, Nejla; Courjault-Radé, Pierre

    2018-02-01

    Temperature, pH and trace elements (F, P, Cr, Cu, Zn, Cd, and Pb) contents were determined in 16 stations as well as in 2 industrial and 2 domestic discharge sources, in the central coastal area of the Gulf of Gabes. Compared to the northern and southern areas of the study area, the highest contents of contaminants were reached in the central area which hosts the coastal industrial complex. The seawater in this central area was also found to be acid and of higher temperature. Based on the Water Pollution Index results, an increasing degradation gradient of the seawater quality was revealed from northern and/or southern stations to central ones, categorized as 'strongly to seriously affected'. Phosphogypsum wastes dumped by the Tunisian Chemical Group (GCT) seem to have continuously degraded the seawater quality in the study area. A rapid intervention is needed to stop the effects on the marine environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Paleogeographic variations of pedogenic carbonate delta13C values from Koobi Fora, Kenya: implications for floral compositions of Plio-Pleistocene hominin environments.

    Science.gov (United States)

    Quinn, Rhonda L; Lepre, Christopher J; Wright, James D; Feibel, Craig S

    2007-11-01

    Plio-Pleistocene East African grassland expansion and faunal macroevolution, including that of our own lineage, are attributed to global climate change. To further understand environmental factors of early hominin evolution, we reconstruct the paleogeographic distribution of vegetation (C(3)-C(4) pathways) by stable carbon isotope (delta(13)C) analysis of pedogenic carbonates from the Plio-Pleistocene Koobi Fora region, northeast Lake Turkana Basin, Kenya. We analyzed 202 nodules (530 measurements) from ten paleontological/archaeological collecting areas spanning environments over a 50-km(2) area. We compared results across subregions in evolving fluviolacustrine depositional environments in the Koobi Fora Formation from 2.0-1.5 Ma, a stratigraphic interval that temporally brackets grassland ascendancy in East Africa. Significant differences in delta(13)C values between subregions are explained by paleogeographic controls on floral composition and distribution. Our results indicate grassland expansion between 2.0 and 1.75 Ma, coincident with major shifts in basin-wide sedimentation and hydrology. Hypotheses may be correct in linking Plio-Pleistocene hominin evolution to environmental changes from global climate; however, based on our results, we interpret complexity from proximate forces that mitigated basin evolution. An approximately 2.5 Ma tectonic event in southern Ethiopia and northern Kenya exerted strong effects on paleography in the Turkana Basin from 2.0-1.5 Ma, contributing to the shift from a closed, lacustrine basin to one dominated by open, fluvial conditions. We propose basin transformation decreased residence time for Omo River water and expanded subaerial floodplain landscapes, ultimately leading to reduced proportions of wooded floras and the establishment of habitats suitable for grassland communities.

  19. Transformation of zinc-concentrate in surface and subsurface environments: Implications for assessing zinc mobility/toxicity and choosing an optimal remediation strategy.

    Science.gov (United States)

    Kwon, Man Jae; Boyanov, Maxim I; Yang, Jung-Seok; Lee, Seunghak; Hwang, Yun Ho; Lee, Ju Yeon; Mishra, Bhoopesh; Kemner, Kenneth M

    2017-07-01

    Zinc contamination in near- and sub-surface environments is a serious threat to many ecosystems and to public health. Sufficient understanding of Zn speciation and transport mechanisms is therefore critical to evaluating its risk to the environment and to developing remediation strategies. The geochemical and mineralogical characteristics of contaminated soils in the vicinity of a Zn ore transportation route were thoroughly investigated using a variety of analytical techniques (sequential extraction, XRF, XRD, SEM, and XAFS). Imported Zn-concentrate (ZnS) was deposited in a receiving facility and dispersed over time to the surrounding roadside areas and rice-paddy soils. Subsequent physical and chemical weathering resulted in dispersal into the subsurface. The species identified in the contaminated areas included Zn-sulfide, Zn-carbonate, other O-coordinated Zn-minerals, and Zn species bound to Fe/Mn oxides or clays, as confirmed by XAFS spectroscopy and sequential extraction. The observed transformation from S-coordinated Zn to O-coordinated Zn associated with minerals suggests that this contaminant can change into more soluble and labile forms as a result of weathering. For the purpose of developing a soil washing remediation process, the contaminated samples were extracted with dilute acids. The extraction efficiency increased with the increase of O-coordinated Zn relative to S-coordinated Zn in the sediment. This study demonstrates that improved understanding of Zn speciation in contaminated soils is essential for well-informed decision making regarding metal mobility and toxicity, as well as for choosing an appropriate remediation strategy using soil washing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Properties of small instream wood as a logjam clogging agent: Implications for clogging dynamics based on wood density, water content, and depositional environment

    Science.gov (United States)

    Haga, Hirokazu; Moriishida, Takuya; Morishita, Naoya; Fujimoto, Takaaki

    2017-11-01

    In cooperation with large instream wood (LW) within logjams, small instream wood (SW) can control downstream flux of sediment and particulate organic matter and can play an important role for stream ecosystems. However, information regarding the density and moisture content of SW-which affects wood transport, wood decay, and mass loading-is limited. Here we investigated the SW properties, i.e., density under field conditions (in situ density), basic density, volumetric water content, and depositional environment of SW sampled from five logjams and their backwater areas in two headwater streams (second- and third-order streams) surrounded by mixed broadleaf-conifer forests in western Japan. The in situ density ranged from 0.49 to 1.25 g cm- 3, and pieces with densities > 1.0 g cm- 3 accounted for 45% of all samples. Additionally, the in situ density of SW closely related to the volumetric water content (r2 = 0.76) rather than the basic density as an index of solidity or decay condition of wood. The SW that was partially submerged in water had a higher volumetric water content than SW exposed to air. These results indicate that a nonfloating transport cannot be ignored as an important mechanism for SW movement and that in situ density depends not on the solidity of the wood but on water sorption by SW. However, waterlogged SW should be well decayed because it has a lower basic density than air-exposed and sediment-buried SW. We conclude that the moisture conditions of the depositional environment can affect subsequent transport and decay processes of SW. Moreover, most waterlogged and sediment-buried SW, because of its high in situ density (> 1.0 g cm- 3), may contribute to clogging between the channel bed and LW that initiate a logjam during future movements.

  1. The importance of leadership style and psychosocial work environment to staff-assessed quality of care: implications for home help services.

    Science.gov (United States)

    Westerberg, Kristina; Tafvelin, Susanne

    2014-09-01

    Work in home help services is typically conducted by an assistant nurse or nursing aide in the home of an elderly person, and working conditions have been described as solitary with a high workload, little influence and lack of peer and leader support. Relations between leadership styles, psychosocial work environment and a number of positive and negative employee outcomes have been established in research, but the outcome in terms of quality of care has been addressed to a lesser extent. In the present study, we aimed to focus on working conditions in terms of leadership and the employee psychosocial work environment, and how these conditions are related to the quality of care. The hypothesis was that the relation between a transformational leadership style and quality of care is mediated through organisational and peer support, job control and workload. A cross-sectional survey design was used and a total of 469 questionnaires were distributed (March-April 2012) to assistant nurses in nine Swedish home help organisations, including six municipalities and one private organisation, representing both rural and urban areas (302 questionnaires were returned, yielding a 65% response rate). The results showed that our hypothesis was supported and, when indirect effects were also taken into consideration, there was no direct effect of leadership style on quality of care. The mediated model explained 51% of the variance in quality of care. These results indicate that leadership style is important not only to employee outcomes in home help services but is also indirectly related to quality of care as assessed by staff members. © 2013 John Wiley & Sons Ltd.

  2. The Surface UV Environment on Planets Orbiting M Dwarfs: Implications for Prebiotic Chemistry and the Need for Experimental Follow-up

    International Nuclear Information System (INIS)

    Ranjan, Sukrit; Sasselov, Dimitar D.; Wordsworth, Robin

    2017-01-01

    Potentially habitable planets orbiting M dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years because of a confluence of observational effects. Simultaneously, recent experimental and theoretical work suggests that UV light may have played a key role in the origin of life on Earth, especially the origin of RNA. Characterizing the UV environment on M-dwarf planets is important for understanding whether life as we know it could emerge on such worlds. In this work, we couple radiative transfer models to observed M-dwarf spectra to determine the UV environment on prebiotic Earth-analog planets orbiting M dwarfs. We calculate dose rates to quantify the impact of different host stars on prebiotically important photoprocesses. We find that M-dwarf planets have access to 100–1000 times less bioactive UV fluence than the young Earth. It is unclear whether UV-sensitive prebiotic chemistry that may have been important to abiogenesis, such as the only known prebiotically plausible pathways for pyrimidine ribonucleotide synthesis, could function on M-dwarf planets. This uncertainty affects objects like the recently discovered habitable-zone planets orbiting Proxima Centauri, TRAPPIST-1, and LHS 1140. Laboratory studies of the sensitivity of putative prebiotic pathways to irradiation level are required to resolve this uncertainty. If steady-state M-dwarf UV output is insufficient to power these pathways, transient elevated UV irradiation due to flares may suffice; laboratory studies can constrain this possibility as well.

  3. The Surface UV Environment on Planets Orbiting M Dwarfs: Implications for Prebiotic Chemistry and the Need for Experimental Follow-up

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, Sukrit; Sasselov, Dimitar D. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Wordsworth, Robin, E-mail: sranjan@cfa.harvard.edu [Harvard Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02140 (United States)

    2017-07-10

    Potentially habitable planets orbiting M dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years because of a confluence of observational effects. Simultaneously, recent experimental and theoretical work suggests that UV light may have played a key role in the origin of life on Earth, especially the origin of RNA. Characterizing the UV environment on M-dwarf planets is important for understanding whether life as we know it could emerge on such worlds. In this work, we couple radiative transfer models to observed M-dwarf spectra to determine the UV environment on prebiotic Earth-analog planets orbiting M dwarfs. We calculate dose rates to quantify the impact of different host stars on prebiotically important photoprocesses. We find that M-dwarf planets have access to 100–1000 times less bioactive UV fluence than the young Earth. It is unclear whether UV-sensitive prebiotic chemistry that may have been important to abiogenesis, such as the only known prebiotically plausible pathways for pyrimidine ribonucleotide synthesis, could function on M-dwarf planets. This uncertainty affects objects like the recently discovered habitable-zone planets orbiting Proxima Centauri, TRAPPIST-1, and LHS 1140. Laboratory studies of the sensitivity of putative prebiotic pathways to irradiation level are required to resolve this uncertainty. If steady-state M-dwarf UV output is insufficient to power these pathways, transient elevated UV irradiation due to flares may suffice; laboratory studies can constrain this possibility as well.

  4. Sense of place as a determinant of people's attitudes towards the environment: implications for natural resources management and planning in the Great Barrier Reef, Australia.

    Science.gov (United States)

    Larson, Silva; De Freitas, Debora M; Hicks, Christina C

    2013-03-15

    Integrating people's values and perceptions into planning is essential for the successful management of natural resources. However, successful implementation of natural resources management decisions on the ground is a complex task, which requires a comprehensive understanding of a system's social and ecological linkages. This paper investigates the relationship between sense of place and people's attitudes towards their natural environment. Sense of place contributes towards shaping peoples' beliefs, values and commitments. Here, we set out to explore how these theoretical contributions can be operationalized for natural resources management planning in the Great Barrier Reef region of Australia. We hypothesise that the region's diverse range of natural resources, conservation values and management pressures might be reflected in people's attachment to place. To tests this proposition, variables capturing socio-demographics, personal wellbeing and a potential for sense of place were collected via mail-out survey of 372 residents of the region, and tested for relationships using multivariate regression and redundancy orientation analyses. Results indicate that place of residence within the region, involvement in community activities, country of birth and the length of time respondents lived in the region are important determinants of the values assigned to factors related to the natural environment. This type of information is readily available from National Census and thus could be incorporated into the planning of community engagement strategies early in the natural resources management planning process. A better understanding of the characteristics that allow sense of place meanings to develop can facilitate a better understanding of people's perceptions towards environmental and biodiversity issues. We suggest that the insights gained from this study can benefit environmental decision making and planning in the Great Barrier Reef region; and that sense of place

  5. Modelling the dispersion of treated wastewater in a shallow coastal wind-driven environment, Geographe Bay, Western Australia: implications for environmental management.

    Science.gov (United States)

    Dunn, Ryan J K; Zigic, Sasha; Shiell, Glenn R

    2014-10-01

    Numerical models are useful for predicting the transport and fate of contaminants in dynamic marine environments, and are increasingly a practical solution to environmental impact assessments. In this study, a three-dimensional hydrodynamic model and field data were used to validate a far-field dispersion model that, in turn, was used to determine the fate of treated wastewater (TWW) discharged to the ocean via a submarine ocean outfall under hypothetical TWW flows. The models were validated with respect to bottom and surface water current speed and direction, and in situ measurements of total nitrogen and faecal coliforms. Variations in surface and bottom currents were accurately predicted by the model as were nutrient and coliform concentrations. Results indicated that the ocean circulation was predominately wind driven, evidenced by relatively small oscillations in the current speeds along the time-scale of the tide, and that dilution mixing zones were orientated in a predominantly north-eastern direction from the outfall and parallel to the coastline. Outputs of the model were used to determine the 'footprint' of the TWW plume under a differing discharge scenario and, particularly, whether the resultant changes in TWW contaminants, total nitrogen and faecal coliforms would meet local environmental quality objectives (EQO) for ecosystem integrity, shellfish harvesting and primary recreation. Modelling provided a practical solution for predicting the dilution of contaminants under a hypothetical discharge scenario and a means for determining the aerial extent of exclusion zones, where the EQOs for shellfish harvesting and primary recreation may not always be met. Results of this study add to the understanding of regional discharge conditions and provide a practical case study for managing impacts to marine environments under a differing TWW discharge scenario, in comparison to an existing scenario.

  6. Distribution of iron- and sulfate-reducing bacteria across a coastal acid sulfate soil (CASS environment: implications for passive bioremediation by tidal inundation

    Directory of Open Access Journals (Sweden)

    Yu-Chen eLing

    2015-07-01

    Full Text Available Coastal acid sulfate soils (CASS constitute a serious and global environmental problem. Oxidation of iron sulfide minerals exposed to air generates sulfuric acid with consequently negative impacts on coastal and estuarine ecosystems. Tidal inundation represents one current treatment strategy for CASS, with the aim of neutralizing acidity by triggering microbial iron- and sulfate-reduction and inducing the precipitation of iron-sulfides. Although well-known functional guilds of bacteria drive these processes, their distributions within CASS environments, as well as their relationships to tidal cycling and the availability of nutrients and electron acceptors, are poorly understood. These factors will determine the long-term efficacy of passive CASS remediation strategies. Here we studied microbial community structure and functional guild distribution in sediment cores obtained from ten depths ranging from 0-20 cm in three sites located in the supra-, inter- and sub-tidal segments, respectively, of a CASS-affected salt marsh (East Trinity, Cairns, Australia. Whole community 16S rRNA gene diversity within each site was assessed by 454 pyrotag sequencing and bioinformatic analyses in the context of local hydrological, geochemical and lithological factors. The results illustrate spatial overlap, or close association, of iron- and sulfate-reducing bacteria in an environment rich in organic matter and controlled by parameters such as acidity, redox potential, degree of water saturation, and mineralization. The observed spatial distribution implies the need for empirical understanding of the timing, relative to tidal cycling, of various terminal electron-accepting processes that control acid generation and biogeochemical iron and sulfur cycling.

  7. Radioruthenium in the environment

    International Nuclear Information System (INIS)

    Iwashima, Kiyoshi; Morita, Shigeki.

    1979-01-01

    A change in the amount of radioruthenium in the environment (due to nuclear tests and drainage from atomic energy plants) and the exposure dose are discussed. The level of 106 Ru in the environment due to radioactive fallout, changes in the level, and the characteristics of these changes are reported. Pollution caused by 106 Ru in drainage from atomic energy plants, especially from the Windscale reprocessing factory in the United Kingdom (which release Ru in the greatest amount), changes in the amount of Ru released and in the levels of environmental pollution, and the movement of Ru in the environment are considered. The intake of Ru into the human body by consumption of food produced in polluted areas and by inspiration of Ru present in the air is estimated. (Tsunoda, M.)

  8. Recognizing nitrogen dopant atoms in graphene using atomic force microscopy

    DEFF Research Database (Denmark)

    van der Heijden, Nadine J.; Smith, Daniel; Calogero, Gaetano

    2016-01-01

    as a benchmark, we show that the position of the dopant atoms can be determined using atomic force microscopy. Specifically, the frequency shift-distance curves Delta f(z) acquired above a N atom are significantly different from the curves measured over a C atom. Similar behavior was found for N-doped graphene...

  9. Investigation of dye laser excitation of atomic systems

    International Nuclear Information System (INIS)

    Abate, J.A.

    1977-01-01

    A stabilized cw dye laser system and an optical pumping scheme for a sodium atomic beam were developed, and the improvements over previously existing systems are discussed. A method to stabilize both the output intensity and the frequency of the cw dye laser for periods of several hours is described. The fluctuation properties of this laser are investigated by photon counting and two-time correlation measurements. The results show significant departures from the usual single-mode laser theory in the region of threshold and below. The implications of the deviation from accepted theory are discussed. The atomic beam system that was constructed and tested is described. A method of preparing atomic sodium so that it behaves as a simple two-level atom is outlined, and the results of some experiments to study the resonant interaction between the atoms and the dye laser beam are presented

  10. Exposure of Arabidopsis thaliana to hypobaric environments: implications for low-pressure bioregenerative life support systems for human exploration missions and terraforming on Mars.

    Science.gov (United States)

    Richards, Jeffrey T; Corey, Kenneth A; Paul, Anna-Lisa; Ferl, Robert J; Wheeler, Raymond M; Schuerger, Andrew C

    2006-12-01

    Understanding how hypobaria can affect net photosynthetic (P (net)) and net evapotranspiration rates of plants is important for the Mars Exploration Program because low-pressured environments may be used to reduce the equivalent system mass of near-term plant biology experiments on landers or future bioregenerative advanced life support systems. Furthermore, introductions of plants to the surface of a partially terraformed Mars will be constrained by the limits of sustainable growth and reproduction of plants to hypobaric conditions. To explore the effects of hypobaria on plant physiology, a low-pressure growth chamber (LPGC) was constructed that maintained hypobaric environments capable of supporting short-term plant physiological studies. Experiments were conducted on Arabidopsis thaliana maintained in the LPGC with total atmospheric pressures set at 101 (Earth sea-level control), 75, 50, 25 or 10 kPa. Plants were grown in a separate incubator at 101 kPa for 6 weeks, transferred to the LPGC, and acclimated to low-pressure atmospheres for either 1 or 16 h. After 1 or 16 h of acclimation, CO(2) levels were allowed to drawdown from 0.1 kPa to CO(2) compensation points to assess P (net) rates under different hypobaric conditions. Results showed that P (net) increased as the pressures decreased from 101 to 10 kPa when CO(2) partial pressure (pp) values were below 0.04 kPa (i.e., when ppCO2 was considered limiting). In contrast, when ppCO(2) was in the nonlimiting range from 0.10 to 0.07 kPa, the P (net) rates were insensitive to decreasing pressures. Thus, if CO(2 )concentrations can be kept elevated in hypobaric plant growth modules or on the surface of a partially terraformed Mars, P (net) rates may be relatively unaffected by hypobaria. Results support the conclusions that (i) hypobaric plant growth modules might be operated around 10 kPa without undue inhibition of photosynthesis and (ii) terraforming efforts on Mars might require a surface pressure of at least 10

  11. Geochemistry of the metasedimentary rocks from the Male Karpaty Mts. (Western Carpathians): implications for protolith, provenance, sedimentary environment and tectonic setting

    Science.gov (United States)

    Meres, S.; Ivan, P.

    2003-04-01

    The Male Karpaty Mts. represent connecting link between the Western Carpathians and Eastern Alps. They are composed of (1) Early Paleozoic basement and (2) Mesozoic cover. Based on lithology and basalt geochemistry the Early Paleozoic basement is divided into two lithostratigraphic groups: (1) Pernek Group represented by incomplete dismembered ophiolite sequences Pre-Visean in age and (2) Pezinok Group supposed to be a fragment of the Devonian extensional rift basin. Both groups were intruded by granitoid batoliths 348±4 My old and underwent contact or periplutonic metamorphic alterations variable in intensity. Metasedimentary rocks of the Pernek Group are represented by small amount of black shales and metacherts associated with small lenses of stratiform pyrite ores. In the Pezinok Group metasedimentary rocks are highly dominated. Phyllites and gneisses sporadically with the organic matter admixture belong to most frequent rock types. Metamorphosed limestones associated with basaltic hyaloclastites occur sporadically only. The distribution of trace elements with the limited fractionation during weathering, transport and deposition processes and immobile in metamorphosis (REE, Th, Hf, Sc) have been mainly used for protolith, provenance and depositional environment studies. Chemical composition of the black shales from the Pernek Group indicate their mixed sedimentary protolith which was formed in oceanic environment and was composed of four components: (1) pelagic chert, (2) organic matter, (3) fine-grained terrigenous component and (4) weathered/hydrothermally altered basalt close to N-MORB. Negative Ce-anomaly, LaN/YbN<6 and Th/Yb<2 are typical. Protolith of metasedimentary rocks (including rocks with organic matter admixture) from the Pezinok Group seems to be close to the immature greywackes of the ensialic island arc provenance derived from an acidic/intermediate magmatic source. They display no Ce-anomaly, negative Eu-anomaly typical for greywackes (Eu

  12. Effects of growth phase on the membrane lipid composition of the thaumarchaeon Nitrosopumilus maritimus and their implications for archaeal lipid distributions in the marine environment

    Science.gov (United States)

    Elling, Felix J.; Könneke, Martin; Lipp, Julius S.; Becker, Kevin W.; Gagen, Emma J.; Hinrichs, Kai-Uwe

    2014-09-01

    The characteristic glycerol dibiphytanyl glycerol tetraether membrane lipids (GDGTs) of marine ammonia-oxidizing archaea (AOA) are widely used as biomarkers for studying their occurrence and distribution in marine environments and for reconstructing past sea surface temperatures using the TEX86 index. Despite an increasing use of GDGT biomarkers in microbial ecology and paleoceanography, the physiological and environmental factors influencing lipid composition in AOA, in particular the cyclization of GDGTs, remain unconstrained. We investigated the effect of metabolic state on the composition of intact polar and core lipids and the resulting TEX86 paleothermometer in pure cultures of the marine AOA Nitrosopumilus maritimus as a function of growth phase. The cellular lipid content ranged from 0.9 to 1.9 fg cell-1 and increased during growth but was lower in the stationary phases, indicating changes in average cell size in response to metabolic status. The relative abundances of monoglycosidic GDGTs increased from 27% in early growth phase to 60% in late stationary phase, while monohydroxylated GDGTs increased only slightly. The proportions of characteristic hexose-phosphohexose GDGTs were up to 7-fold higher during growth than in stationary phase, suggesting that they are valuable biomarkers for the metabolically active fraction of AOA assemblages in the environment. Methoxy archaeol was identified as novel, genuine archaeal lipid of yet unknown function; it is one of the most abundant single compounds in the lipidome of N. maritimus. TEX86 values of individual intact GDGTs and total GDGTs differed substantially, were generally lower during early and late growth phases than in stationary phase, and did not reflect growth temperature. Consequently, our results strongly suggest that biosynthesis is at least partially responsible for the systematic offsets in TEX86 values between different intact polar GDGT classes observed previously in environmental samples

  13. Reactivity of amino acid anions with nitrogen and oxygen atoms.

    Science.gov (United States)

    Wang, Zhe-Chen; Li, Ya-Ke; He, Sheng-Gui; Bierbaum, Veronica M

    2018-02-14

    For many decades, astronomers have searched for biological molecules, including amino acids, in the interstellar medium; this endeavor is important for investigating the hypothesis of the origin of life from space. The space environment is complex and atomic species, such as nitrogen and oxygen atoms, are widely distributed. In this work, the reactions of eight typical deprotonated amino acids (glycine, alanine, cysteine, proline, aspartic acid, histidine, tyrosine, and tryptophan) with ground state nitrogen and oxygen atoms are studied by experiment and theory. These amino acid anions do not react with nitrogen atoms. However, the reactions of these ions with oxygen atoms show an intriguing variety of ionic products and the reaction rate constants are of the order of 10 -10 cm 3 s -1 . Density functional calculations provide detailed mechanisms of the reactions, and demonstrate that spin conversion is essential for some processes. Our study provides important data and insights for understanding the kinetic and dynamic behavior of amino acids in space environments.

  14. Comparison of pore space textural characteristics of natural stone exposed to real weathering environment and/or subjected to accelerated weathering tests: implications for durability assessment

    Science.gov (United States)

    Prikryl, Richard; Weishauptová, Zuzana

    2017-04-01

    One of the key questions in the debate on durability of natural stone is related to the relevance of accelerated weathering tests for durability assessments, specifically whether similar material responses can be achieved? In the recent study, specimens of opuka stone (extremely fine-grained clayey-calcareous silicite) was subjected to accelerated weathering tests in a climatic chamber (sulphur dioxide atmosphere, freezing/thawing). After completion of certain number of cycles, pore space textural characteristics by means of mercury porosimetry were studied. These data were compared with porosimetric data obtained from a piece of stone, sampled from a carved stone altar located in the interior of the St. Vitus Cathedral (Prague, Czech Republic) which was affected by 150-years lasting indoor decay processes (cyclic themohygric stresses due to variable indoor atmospheric conditions). Interestingly, the pore space textural characteristics of these two sets of specimens are closely related and show some distinct features different from fresh, non-weathered material. Our observation therefore supports relevance of some accelerated weathering simulations; however, conditions of these simulations must be based on parameters of real environment.

  15. Compilation of data from hadronic atoms

    International Nuclear Information System (INIS)

    Poth, H.

    1979-01-01

    This compilation is a survey of the existing data of hadronic atoms (pionic-atoms, kaonic-atoms, antiprotonic-atoms, sigmonic-atoms). It collects measurements of the energies, intensities and line width of X-rays from hadronic atoms. Averaged values for each hadronic atom are given and the data are summarized. The listing contains data on 58 pionic-atoms, on 54 kaonic-atoms, on 23 antiprotonic-atoms and on 20 sigmonic-atoms. (orig./HB) [de

  16. Accelerators for atomic energy research

    International Nuclear Information System (INIS)

    Shibata, Tokushi

    1999-01-01

    The research and educational activities accomplished using accelerators for atomic energy research were studied. The studied items are research subjects, facility operation, the number of master theses and doctor theses on atomic energy research using accelerators and the future role of accelerators in atomic energy research. The strategy for promotion of the accelerator facility for atomic energy research is discussed. (author)

  17. Atomic nucleus and elementary particles

    International Nuclear Information System (INIS)

    Zakrzewski, J.

    1976-01-01

    Negatively charged leptons and hadrons can be incorporated into atomic shells forming exotic atoms. Nucleon resonances and Λ hyperons can be considered as constituents of atomic nuclei. Information derived from studies of such exotic systems enriches our knowledge of both the interactions of elementary particles and of the structure of atomic nuclei. (author)

  18. Spontaneous spherical symmetry breaking in atomic confinement

    Science.gov (United States)

    Sveshnikov, Konstantin; Tolokonnikov, Andrey

    2017-07-01

    The effect of spontaneous breaking of initial SO(3) symmetry is shown to be possible for an H-like atom in the ground state, when it is confined in a spherical box under general boundary conditions of "not going out" through the box surface (i.e. third kind or Robin's ones), for a wide range of physically reasonable values of system parameters. The most novel and nontrivial result, which has not been reported previously, is that such an effect takes place not only for attractive, but also for repulsive interactions of atomic electrons with the cavity environment. Moreover, in the limit of a large box size R ≫ aB the regime of an atom, soaring over a plane with boundary condition of "not going out", is reproduced, rather than a spherically symmetric configuration, which would be expected on the basis of the initial SO(3) symmetry of the problem.

  19. Vibration dynamics of single atomic nanocontacts

    International Nuclear Information System (INIS)

    Khater, A; Bourahla, B; Tigrine, R

    2007-01-01

    The motivation for this work is to introduce a model for an atomic nanocontact, whereby its mechanical properties can be analysed via the local spectra. The model system consists of two sets of triple parallel semi-infinite atomic chains joined by a single atom in between. We calculate the vibration spectra and the local densities of vibration states, in the harmonic approximation, for the irreducible set of sites that constitute the nanocontact domain. The nanocontact observables are numerically calculated for different cases of elastic hardening and softening, to investigate how the local dynamics can respond to changes in the microscopic environment on the domain. We have also calculated the phonon scattering and coherent conductance at the nanocontact, derived in a Landauer-Buettiker matrix approach. The analysis of the spectra, of the densities of vibration states, and of the phonon conductance, identifies characteristic features and demonstrates the central role of a core subset of sites in the nanocontact domain

  20. Externalities of energy and atomic power

    International Nuclear Information System (INIS)

    2006-09-01

    Energy technology ensures not only energy supply but also has great impacts on society and environments. Economical value and effect evaluation alone doesn't mean appropriate so the evaluation of 'externalities' should be appreciated. In order to assess atomic power in this context, the Atomic Energy Society of Japan set up a research committee on 'externalities of energy and atomic power' from April 2002 to March 2006, whose activities were described in this report. In addition to environmental effects and environmental externalities, four areas were newly studied as follows: (1) biological effects of low dose rate exposure and externalities, (2) externalities as social/economical effects including stable supply and security, (3) energy technologies evaluation and (4) social choice and decision-making. (T. Tanaka)

  1. The Effect of Shoreline Recreational Angling Activities on Aquatic and Riparian Habitat Within an Urban Environment: Implications for Conservation and Management

    Science.gov (United States)

    O'Toole, Amanda C.; Hanson, Kyle C.; Cooke, Steven J.

    2009-08-01

    There is growing concern that recreational shoreline angling activity may negatively impact littoral and riparian habitats independent of any direct or indirect influences of fish harvest or fishing mortality through mechanisms such as disturbance (e.g., trampling, erosion) and pollution (e.g., littering). We sampled a suite of aquatic and terrestrial variables (i.e., water quality, aquatic and terrestrial macrophytes, soil compaction, anthropogenic refuse) at 14 high shoreline angling-activity sites (identified by way of interviews with conservation officers and angling clubs) within an urban area (Ottawa, Canada). For each high angling-activity site, a nearby corresponding low angling-activity site was sampled for comparison. We found that the percentage of barren area and soil compaction were greater in areas of high angling activity compared with areas that experienced relatively low angling activity. In addition, terrestrial and aquatic macrophyte density, height, and diversity were lower at high angling-activity sites. Angling- and non-angling-related litter was present in large quantities at each of the high angling-activity sites, and comparatively little litter was found at low angling-activity sites. Collectively, these findings indicate that shoreline angling does alter the riparian environment, contributing to pollution and environmental degradation in areas of high angling intensity. With growing interest in providing urban angling opportunities and in response to increasing interest in developing protected areas and parks, a better understanding of the ecologic impacts of shoreline angling is necessary to address multiuser conflicts, to develop angler outreach and educational materials, and to optimize management of angling effort to maintain ecologic integrity of riparian and aquatic ecosystems.

  2. PDE5 inhibition improves object memory in standard housed rats but not in rats housed in an enriched environment: implications for memory models?

    Directory of Open Access Journals (Sweden)

    Sven Akkerman

    Full Text Available Drug effects are usually evaluated in animals housed under maximally standardized conditions. However, it is assumed that an enriched environment (EE more closely resembles human conditions as compared to maximally standardized laboratory conditions. In the present study, we examined the acute cognition enhancing effects of vardenafil, a PDE5 inhibitor, which stimulates protein kinase G/CREB signaling in cells, in three different groups of male Wistar rats tested in an object recognition task (ORT. Rats were either housed solitarily (SOL or socially (SOC under standard conditions, or socially in an EE. Although EE animals remembered object information longer in the vehicle condition, vardenafil only improved object memory in SOL and SOC animals. While EE animals had a heavier dorsal hippocampus, we found no differences between experimental groups in total cell numbers in the dentate gyrus, CA2-3 or CA1. Neither were there any differences in markers for pre- and postsynaptic density. No changes in PDE5 mRNA- and protein expression levels were observed. Basal pCREB levels were increased in EE rats only, whereas β-catenin was not affected, suggesting specific activation of the MAP kinase signaling pathway and not the AKT pathway. A possible explanation for the inefficacy of vardenafil could be that CREB signaling is already optimally stimulated in the hippocampus of EE rats. Since previous data has shown that acute PDE5 inhibition does not improve memory performance in humans, the use of EE animals could be considered as a more valid model for testing cognition enhancing drugs.

  3. The effect of shoreline recreational angling activities on aquatic and riparian habitat within an urban environment: implications for conservation and management.

    Science.gov (United States)

    O'Toole, Amanda C; Hanson, Kyle C; Cooke, Steven J

    2009-08-01

    There is growing concern that recreational shoreline angling activity may negatively impact littoral and riparian habitats independent of any direct or indirect influences of fish harvest or fishing mortality through mechanisms such as disturbance (e.g., trampling, erosion) and pollution (e.g., littering). We sampled a suite of aquatic and terrestrial variables (i.e., water quality, aquatic and terrestrial macrophytes, soil compaction, anthropogenic refuse) at 14 high shoreline angling-activity sites (identified by way of interviews with conservation officers and angling clubs) within an urban area (Ottawa, Canada). For each high angling-activity site, a nearby corresponding low angling-activity site was sampled for comparison. We found that the percentage of barren area and soil compaction were greater in areas of high angling activity compared with areas that experienced relatively low angling activity. In addition, terrestrial and aquatic macrophyte density, height, and diversity were lower at high angling-activity sites. Angling- and non-angling-related litter was present in large quantities at each of the high angling-activity sites, and comparatively little litter was found at low angling-activity sites. Collectively, these findings indicate that shoreline angling does alter the riparian environment, contributing to pollution and environmental degradation in areas of high angling intensity. With growing interest in providing urban angling opportunities and in response to increasing interest in developing protected areas and parks, a better understanding of the ecologic impacts of shoreline angling is necessary to address multiuser conflicts, to develop angler outreach and educational materials, and to optimize management of angling effort to maintain ecologic integrity of riparian and aquatic ecosystems.

  4. Molecular Analysis of Flood Deposits in the Tennessee River Valley: Implications for Understanding Carbon Cycling in Fluvial Environments and Anthropogenic Impacts

    Science.gov (United States)

    Blackaby, E.; Craven, O. D.; Hockaday, W. C.; Forman, S. L.; Stinchcomb, G. E.

    2017-12-01

    The middle Tennessee River Valley contains both historic and prehistoric (>AD 1600) flood deposits. Stratigraphic sequences of stacked flood deposits that often bury soils provide new insights on organic matter transported and preserved prior to and after European colonization. This study focused on understanding carbon cycling within a dynamic fluvial system and quantifying the anthropogenic effect on flood processes through the analysis of molecular components of the organic matter. The data may be helpful in discerning the organic geochemical fingerprint for historic and prehistoric flood deposits. Ten samples were collected from three sites at varying depths and dated using optically stimulated luminescence (OSL). All samples underwent solid-state cross polar 13C NMR analysis at twelve kilohertz, and a molecular mixing model (MMM) was used to determine the molecular components of the organic matter present in each sample. The MMM categorized carbon molecules present in each sample in terms of carbohydrate, protein, lipid, lignin, char, or pure carbonyl. Char was the most prominent molecular component of all ten samples ranging from 28.7 to 55.9% and comprised larger percentages in prehistoric deposits. The historic deposits, while still char dominated, showed more molecular diversity with higher percentages in non-char carbon groups. The carbonyl, lipid, and carbohydrate groups are present throughout all the samples with the carbonyl ranging from 9.3 to 31.4%, the lipid from 5.5 to 16.7%, and the carbohydrate from 4.4 to 16.9%. The high amount of carbonyl throughout the samples indicates that the deposits existed in a highly oxidizing environment. Differences in the presence and amount of carbon groups between historic and prehistoric flood deposits potentially reflect diagenic alternation of organic matter through time, changes in human land use, or some combination processes. These preliminary results possibly indicate changes in carbon pools accessed with

  5. Ex vivo evaluation of femtosecond pulse laser incision of urinary tract tissue in a liquid environment: implications for endoscopic treatment of benign ureteral strictures.

    Science.gov (United States)

    Liang, Jun-Hao; Kang, Jian; Pan, Yu-Long; Zhang, Liang; Qi, Jun

    2011-08-01

    The femtosecond (FS) pulse laser incises soft tissues with minimal peripheral damage and is a promising cutting tool for ureteroscopic endoureterotomy of benign ureteral strictures. To evaluate the feasibility of applying the FS laser to ureteroscopic endoureterotomy. A commercial Ti:Sapphire regenerative amplifier system (Coherent, RegA 9050, USA) was used in this study. Normal saline, 5% glucose solution, 4% mannitol solution, distilled water, and a 1% (v/v) suspension of whole blood with each of these solutions were tested for their attenuation rate (AR) of the FS laser's power. Bladder specimens from Sprague-Dawley (SD) rats were used as a surrogate model. The laser incised slots of 2 mm in length at bladder samples using three power grades (5×, 10×, and 20× the threshold power) combined with five effective pulse rates (40, 20, 10, 5, and 2.5 kHz), both in air and in normal saline. After samples were processed with standard hematoxylin-eosin staining procedures, the incision depth and collateral damage range were determined microscopically. The ARs of blood suspensions with each of the three isosmotic solutions were significantly higher than the other five solutions (P laser's cutting depth and the collateral damage were increased with the laser power or power density but the collateral damages were less than 100 µm. Microbubble formation was detected in the liquid environments tested and influenced the effective laser power. Endoscopic application of the FS laser is feasible. Microbubble formation with the laser incision, however, may influence cutting effects. Proposed methods to address these issues include increasing the irrigation rate, using distilled water as irrigation or using gas insufflation instead of irrigation. It is necessary to evaluate these methods, as well as the long-term biologic response to laser incision, on living animal models in endoscopic settings before use on humans. Copyright © 2011 Wiley-Liss, Inc.

  6. Rydberg atoms in strong fields

    International Nuclear Information System (INIS)

    Kleppner, D.; Tsimmerman, M.

    1985-01-01

    Experimental and theoretical achievements in studying Rydberg atoms in external fields are considered. Only static (or quasistatic) fields and ''one-electron'' atoms, i.e. atoms that are well described by one-electron states, are discussed. Mainly behaviour of alkali metal atoms in electric field is considered. The state of theoretical investigations for hydrogen atom in magnetic field is described, but experimental data for atoms of alkali metals are presented as an illustration. Results of the latest experimental and theoretical investigations into the structure of Rydberg atoms in strong fields are presented

  7. Sampling the Hydrogen Atom

    Directory of Open Access Journals (Sweden)

    Graves N.

    2013-01-01

    Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.

  8. US Atomic Energy Law

    International Nuclear Information System (INIS)

    1981-01-01

    This is a new volume follows in the series supplementing the volumes 11 and 12 published in 1965 and 1966, updating the collection of Federal Acts and Executive Orders of the President of the United States of America relating to atomic energy legislation. Since the publication of volumes 11 and 12, the US Atomic Energy Act of 1954 alone has been amended 25 times, mainly as a consequence of by the Nuclear Non-Proliferation Act and the Uranium Mill Tailings Radiation Control Act, both of 1978. The Atomic Energy Act of 1954 is supplemented by a selection of the most important Federal Acts, Executive Orders of the President and Resolutions of the Congress. (orig./HSCH) [de

  9. CP violation in atoms

    International Nuclear Information System (INIS)

    Barr, S.M.

    1992-01-01

    Electric dipole moments of large atoms are an excellent tool to search for CP violation beyond the Standard Model. These tell us about the electron EDM but also about CP-violating electron-nucleon dimension-6 operators that arise from Higgs-exchange. Rapid strides are being made in searches for atomic EDMs. Limits on the electron EDM approaching the values which would be expected from Higgs-exchange mediated CP violation have been achieved. It is pointed out that in this same kind of model if tan β is large the effects in atoms of the dimension-6 e - n operators may outweigh the effect of the electron EDM. (author) 21 refs

  10. Long term stability of atomic time scales

    Science.gov (United States)

    Petit, Gérard; Arias, Elisa Felicitas

    2012-08-01

    International Atomic Time TAI gets its stability from some 400 atomic clocks worldwide that generate the free atomic scale EA L and its accuracy from a small number of primary frequency standards (PFS) which frequency measurements are used to steer the EAL frequency. Because TAI is computed in "real - time" (every month) and has operational constraints, it is not optimal and the BIPM computes in deferred time another time scale TT(BIPM), which is based on a weighted average of the evaluations of TAI frequency by the PFS. We show that a point has been reached where the stability of atomic time scales, the accuracy of primary frequency standards, and the capabilities of frequency transfer are approximately at a similar level, in the low 10 - 16 in relative frequency. The goal is now to reach and surpass 1x10 - 16 and the three fields are in various stages of advancement towards this aim. We review the stability and accuracy recently achieved by frequency standards, focusing on primary frequency standards on one hand, and on new secondary realizations e.g. based on optical transitions on the other hand. We study how these performances can translate to the performance of atomic time scales, and the possible implications of the availability of new high - accuracy frequency standards operating on a regular basis. Finally we show how time transfer is trying to keep up with the progresses of frequency standards. Time transfer is presently the limiting factor at short averaging time (e.g. 1 - 2 weeks) but it should not be limiting the long term stability of atomic time scales, which is the main need of many applications in astronomy.

  11. Atoms in Slovakia

    International Nuclear Information System (INIS)

    Danis, D.; Feik, K.; Florek, M.; Kmosena, J.; Chrapan, J.; Morovic, M.; Slugen, V.; Seliga, M.; Valovic, J.

    2006-01-01

    In this book the history of development of using of nuclear energy in the Slovak Republic as well as in the Czechoslovakia (before 1993 year) is presented. The aim of the book is to preserve the memory of the period when the creation and development of nuclear physics, technology, nuclear medicine, radioecology and energetics in Slovakia occurred - as witnessed by people who experienced this period and to adapt it to future generations. The Editorial board of the SNUS collected the views of 60 contributors and distinguished workers - Slovakian experts in nuclear science, education and technology. Calling upon a wide spectrum of experts ensured an objective historical description of the period. A huge amount of subjective views on recent decades were collected and supported by a wealth of photographic documentation. This created a synthesised reflection on the history of the 'atoms' in Slovakia. The book contains 15 tables, 192 black and white and 119 colour pictures from around the world and from places involved in the compilation of the study and with the study of atomic science in Slovakia. The main chapters are as follows: Atoms in the world, Atoms in Slovakia, Atoms in the educational system, Atoms in health services (Radiology, Nuclear medicine, Radiation protection, the Cyclotron centre of the Slovak Republic), Radioecology, Other applications of irradiation, Nuclear energetics (Electric energy in the second half of the 20 th century, NPP Bohunice, NPP Mochovce, the back-end of Nuclear energetics, Big names in Nuclear energetics in Slovakia), Chronology and an Appendix entitled 'Slovak companies in nuclear energetics'

  12. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    Grueebler, W.

    1984-01-01

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  13. Stationary Electron Atomic Model

    Science.gov (United States)

    Pressler, David E.

    1998-04-01

    I will present a novel theory concerning the position and nature of the electron inside the atom. This new concept is consistant with present experimental evidence and adheres strictly to the valence-shell electron-pair repulsion (VSEPR) model presently used in chemistry for predicting the shapes of molecules and ions. In addition, I will discuss the atomic model concept as being a true harmonic oscillator, periodic motion at resonant frequency which produces radiation at discrete frequencies or line spectra is possible because the electron is under the action of two restoring forces, electrostatic attraction and superconducting respulsion of the electron's magnetic field by the nucleus.

  14. Warm Vapor Atom Interferometer

    Science.gov (United States)

    Biedermann, Grant; Wheeler, David; Jau, Yuan-Yu; McGuinness, Hayden

    2014-05-01

    We present a light pulse atom interferometer using room temperature rubidium vapor. Doppler sensitive stimulated Raman transitions forming the atom optical elements inherently select a cold velocity group for the interferometer. The interferometer is configured to be sensitive to accelerations. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  15. Atomic Force Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  16. Korean atomic bomb victims.

    Science.gov (United States)

    Sasamoto, Yukuo

    2009-01-01

    After colonizing Korea, Japan invaded China, and subsequently initiated the Pacific War against the United States, Britain, and their allies. Towards the end of the war, U.S. warplanes dropped atomic bombs on Hiroshima and Nagasaki, which resulted in a large number of Koreans who lived in Hiroshima and Nagasaki suffering from the effects of the bombs. The objective of this paper is to examine the history of Korea atomic bomb victims who were caught in between the U.S., Japan, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea).

  17. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, Michito; Tomonaga, Masao; Amenomori, Tatsuhiko; Matsuo, Tatsuki (Nagasaki Univ. (Japan). School of Medicine)

    1991-03-01

    Characteristic features of leukemia among atomic bomb survivors were studied. The ratio of a single leukemia type to all leukemias was highest for CML in Hiroshima, and the occurrence of CML was thought to be most characteristic for atomic bomb radiation induced leukemia. In the distribution of AML subtypes of FAB classification, there was no M3 cases in 1 Gy or more group, although several atypical AML cases of survivors were observed. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral blood of proximal survivors. (author).

  18. Atoms in Agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Thomas S. [University of Tennessee

    1965-01-01

    Agriculture benefits from the applications of research. Radioactive techniques have been used to study soils, plants, microbes, insects, farm animals, and new ways to use and preserve foodstuffs. Radioactive atoms are not used directly by farmers but are used in research directed by the U. S. Department of Agriculture and Atomic Energy Commission, by the agricultural experiment stations of the various states, and by numerous public and private research institutions. From such research come improved materials and methods which are used on the farm.

  19. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  20. The way that Ibaraki Prefecture has tackled atomic energy

    International Nuclear Information System (INIS)

    Nakata, Hirokatsu; Hirai, Yasuo; Tsuji, Tadashi.

    1996-01-01

    First, the development of the district centering around Tokai Village is mentioned, where at present Japan Atomic Energy Research Institute, Power Reactor and Nuclear Fuel Development Corporation, Japan Atomic Power Co. and others are located. Ibaraki Prefecture investigated the effects that atomic energy facilities exerted economically and socially to the district. As to the social environment investigation related to atomic energy facilities, its purpose, the objects of investigation, the contents and the method of investigation are reported. As to the progress of the development and utilization of atomic energy in Ibaraki Prefecture, 23 establishments are located in the district. Also there are 16 power reactors and research reactors, one fuel reprocessing plant, 4 nuclear fuel fabrication facilities, 86 nuclear fuel using facilities and 28 radioisotope using facilities. Their situations are reported. As to the atomic energy administration of Ibaraki Prefecture, the safety administration and the countermeasures for surrounding areas are explained. The effects exerted to the society and the economy of the district are reported. The results of the investigation of the conscience concerning atomic energy of residents are shown about energy and atomic energy, atomic energy administration, and the relation of atomic energy facilities with the district. (K.I.)

  1. Single atom spectroscopy: Decreased scattering delocalization at high energy losses, effects of atomic movement and X-ray fluorescence yield.

    Science.gov (United States)

    Tizei, Luiz H G; Iizumi, Yoko; Okazaki, Toshiya; Nakanishi, Ryo; Kitaura, Ryo; Shinohara, Hisanori; Suenaga, Kazu

    2016-01-01

    Single atom localization and identification is crucial in understanding effects which depend on the specific local environment of atoms. In advanced nanometer scale materials, the characteristics of individual atoms may play an important role. Here, we describe spectroscopic experiments (electron energy loss spectroscopy, EELS, and Energy Dispersed X-ray spectroscopy, EDX) using a low voltage transmission electron microscope designed towards single atom analysis. For EELS, we discuss the advantages of using lower primary electron energy (30 keV and 60 keV) and higher energy losses (above 800 eV). The effect of atomic movement is considered. Finally, we discuss the possibility of using atomically resolved EELS and EDX data to measure the fluorescence yield for X-ray emission. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Impact of the Paleocene-Eocene Thermal Maximum on Continental Margins and Implications for the Carbon Cycle in Near-Shore Environments

    Science.gov (United States)

    John, C. M.; Bohaty, S. M.; Zachos, J. C.; Sluijs, A.; Gibbs, S.; Brinkhuis, H.; Bralower, T. J.

    2006-12-01

    We present a multi-proxy study of continental shelf and slope deposits from the eastern and western margins of North America across the Paleocene-Eocene Thermal Maximum (PETM, about 55 Ma). The PETM is characterized by rapid global warming, of 5-6 ° C but locally by as much as 8 ° C, and a transient 2.5-6 ‰ global negative excursion in the stable isotopic composition of marine and terrestrial sedimentary carbon (carbon isotope excursion, CIE). The CIE is best explained by the rapid transfer of a large mass of methane from gas hydrate reservoirs into the exogenic carbon pool. The rise in temperature associated with the addition of this carbon appears to have also altered global humidity and precipitation patterns, a feature impacting near-shore depositional facies. The sections investigated are dominanted by siliciclastic sediments with sufficient planktonic and benthic foraminifera, and/or organic matter to construct carbon isotope stratigraphies. Oxygen isotope and TEX86- based estimates of surface water temperatures (SST) on the shelf suggest that average SSTs in mid-latitude near shore environments increased significantly, by more than 5 ° C. Salinities may have decreased as a result of increased runoff. Vertical temperature gradients in the water column appear to have weakened along with deepening of the thermocline, resulting in a weaker stratification The magnitude of the CIE in these coastal sections ranges from 3.5 to 4.5 ‰ , which is slightly larger than in the deep-sea, particularly in planktonic foraminifers. The larger magnitude of the CIE in shelf areas likely reflects a combination of enhanced runoff and higher respiration rates that lowered the mean carbon isotope composition of dissolved inorganic carbon (DIC) in coastal waters during the CIE relative to the open ocean. However, we must not rule out that there may also be truncation of deep-water records, making the CIE less complete. In addition, sedimentation rates and preservation

  3. Texture, mineralogy and geochemistry of the continental slope sediments in front of Los Tuxtlas, Gulf of Mexico, Mexico: implications on weathering, origin and depositional environments

    Science.gov (United States)

    Marca-Castillo, M. E.; Armstrong-Altrin, J.

    2017-12-01

    The textural analysis, mineralogy and geochemistry of two sediment cores recovered from the deep water zone of the southwestern part of the Gulf of Mexico ( 1666 and 1672 m water depth) were studied to infer the provenance and depositional behavior. The textural analysis revealed that both cores are dominated by silt, which occupy more than 50% in both samples and the clay occupy 40%. The petrographic analysis revealed remains of biogenic origin sediments and lithic fragments with an angular shape and low sphericity, indicating a low energy environment and therefore a low level of weathering in the sediment, which suggests that the sediments were not affected by transport and derived from a nearby source rock. In both cores quartz fragments were identified; also volcanic lithic and pyroxenes fragments, which are rocks of intermediate composition and are generally associated with the volcanic activity of the continental margins. SEM-EDS studies showed that the analysed samples have concentrations of minerals such as barite, gibbsite, kaolinite, grossular, magnetite, plagioclase and chlorite, which are probably derived from the mainland to the deep sea zone. In the trace element analysis it was observed a low Sc content, while Co, Ni, V and Cu are slightly enriched with respect to the upper continental crust; this enrichment is related to sediments from intermediate sources. The sediments are classified as shale in the log (SiO2 / Al2O3) - log (Fe2O / K2O) diagram. The fine particles of the shale indicate that a deposit occurred as a result of the gradual sedimentation due to relatively non-turbulent currents, which is consistent with the petrographic analysis. The geochemical features of major and trace elements suggest sediments were derived largely from the natural andesite erosion of coastal regions along the Gulf of Mexico. High values of Fe2O3 and MnO are observed in the upper intervals, reflecting the influence of volcanic sediments. The major element

  4. Atomic compressibility and reversible insertion of atoms into solids

    International Nuclear Information System (INIS)

    Connerade, J.P.; Semaoune, R.

    2000-01-01

    We developed a theoretical model to investigate the compressibility of atoms. Atoms are confined inside a spherical cavity, simulated numerically by a finite repulsive potential barrier. The energy levels and wavefunctions of confined atoms are determined by solving, for different cavity radii, the relativistic Dirac-Fock equations, including formally the repulsive barrier. The changes in the atomic size and in the ground-state energy level allow one to define a positive isotropic pressure exerted on the confined atom. The model is applied to atomic caesium and it is demonstrated quantitatively that the remarkable compressibility of caesium originates from a purely atomic mechanism, namely the pressure-induced collapse of the 5d orbital. We propose that this mechanism can also drive, at an atomic level, a reversible insertion of atoms into solids. Applications to lithium-ion batteries are briefly discussed at the end of this paper. (author)

  5. Spatially resolved photoionization of ultracold atoms on an atom chip

    International Nuclear Information System (INIS)

    Kraft, S.; Guenther, A.; Fortagh, J.; Zimmermann, C.

    2007-01-01

    We report on photoionization of ultracold magnetically trapped Rb atoms on an atom chip. The atoms are trapped at 5 μK in a strongly anisotropic trap. Through a hole in the chip with a diameter of 150 μm, two laser beams are focused onto a fraction of the atomic cloud. A first laser beam with a wavelength of 778 nm excites the atoms via a two-photon transition to the 5D level. With a fiber laser at 1080 nm the excited atoms are photoionized. Ionization leads to depletion of the atomic density distribution observed by absorption imaging. The resonant ionization spectrum is reported. The setup used in this experiment is suitable not only to investigate mixtures of Bose-Einstein condensates and ions but also for single-atom detection on an atom chip

  6. Atomic collisions related to atomic laser isotope separation

    International Nuclear Information System (INIS)

    Shibata, Takemasa

    1995-01-01

    Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

  7. Sedimentary environments and stratigraphy of the carbonate-silicilastic deposits of the Shirgesht Formation: implications for eustasy and local tectonism in the Kalmard Block, Central Iran

    Directory of Open Access Journals (Sweden)

    aram bayetgoll

    2015-10-01

    Formations along the basement Kalmard Fault. In the present study, three stratigraphic sections (NW-SE transects were measured, described and sampled in the Kalmard area. In these sections, detailed considerations have been given on the lithofacies variations; bed geometry and contacts, faunal content, the potential of trace fossils as tools for reconstructing depositional conditions, sedimentary textures and structures, bounding surfaces, vertical trends and stacking patterns and lateral/vertical variations in facies and thicknesses. The observed siliciclastic facies can readily be interpreted using existing shelf sedimentation and shoreline succession models (e.g. Walker and Plint 1992 . Interpretation carbonate facies have been done on the basis the microfacies analysis (200 thin-sections, sedimentary textures and structures and faunal content (Wilson et al. 1975; Flügel 2010 . In final, internal architecture, characteristics of sedimentary facies, the overall stacking pattern and nature of sequence-bounding unconformities have been investigated to evaluate the influence of regional uplift, local tectonics and eustasy on both along-strike variations in sequence architecture and genetic complexity of sequence boundaries.     Discussion, Results and Conclusion   The Lower Ordovician Shirgesht Formation in central Iran is composed of siliciclastic and carbonate rocks deposited in diverse coastal and marine shelf environments (tidal flat, lagoon, shoreface, and offshore-shelf and carbonate ramp. Relying on the facies characteristics and stratal geometries, the siliciclastic succession are divided into five facies associations, FA1 (tidal flat, FA2 (lagoon/washoverfan, FA3 (upper shoreface-foreshore, FA4 (lower to middle shoreface, and FA5 (offshore-shelf.Carbonate succession of this formation based on lithology, sedimentary characteristics and textures divided into four facies belts, FA (tidal flat, FB (lagoon,FC (shoal/barrier island, and FD (open marine. These facies

  8. Sedimentary environments and stratigraphy of the carbonate-silicilastic deposits of the Shirgesht Formation: implications for eustasy and local tectonism in the Kalmard Block, Central Iran

    Directory of Open Access Journals (Sweden)

    reza Mousavi-Harami

    2015-09-01

    Rahdar (Devonian Formations along the basement Kalmard Fault. In the present study, three stratigraphic sections (NW-SE transects were measured, described and sampled in the Kalmard area. In these sections, detailed considerations have been given on the lithofacies variations bed geometry and contacts, faunal content, the potential of trace fossils as tools for reconstructing depositional conditions, sedimentary textures and structures, bounding surfaces, vertical trends and stacking patterns and lateral/vertical variations in facies and thicknesses. The observed siliciclastic facies can readily be interpreted using existing shelf sedimentation and shoreline succession models (e.g. Walker and Plint 1992 . Interpretation carbonate facies have been done on the basis the microfacies analysis (200 thin-sections, sedimentary textures and structures and faunal content (Wilson et al. 1975 Flügel 2010 . In final, internal architecture, characteristics of sedimentary facies, the overall stacking pattern and nature of sequence-bounding unconformities have been investigated to evaluate the influence of regional uplift, local tectonics and eustasy on both along-strike variations in sequence architecture and genetic complexity of sequence boundaries.     Discussion, Results and Conclusion   The Lower Ordovician Shirgesht Formation in central Iran is composed of siliciclastic and carbonate rocks deposited in diverse coastal and marine shelf environments (tidal flat, lagoon, shoreface, and offshore-shelf and carbonate ramp. Relying on the facies characteristics and stratal geometries, the siliciclastic succession are divided into five facies associations, FA1 (tidal flat, FA2 (lagoon/washoverfan, FA3 (upper shoreface-foreshore, FA4 (lower to middle shoreface, and FA5 (offshore-shelf.Carbonate succession of this formation based on lithology, sedimentary characteristics and textures divided into four facies belts, FA (tidal flat, FB (lagoon,FC (shoal/barrier island, and FD

  9. Atomic Physics 16: Sixteenth International Conference on Atomic Physics. Proceedings

    International Nuclear Information System (INIS)

    Baylis, W.E.; Drake, G.W.

    1999-01-01

    These proceedings represent papers presented at the 16th International Conference on Atomic Physics held in Windsor, Ontario, Canada, in August, 1998. The topics discussed included a wide array of subjects in atomic physics such as atom holography, alignment in atomic collisions, coulomb-interacting particles, muon experiments, x-rays from comets, atomic electron collisions in intense laser fields, spectroscopy of trapped ions, and Bose-Einstein condensates. This conference represents the single most important meeting world wide on fundamental advances in atomic physics. There were 30 papers presented at the conference,out of which 4 have been abstracted for the Energy, Science and Technology database

  10. Non-perturbative treatment of relativistic quantum corrections in large Z atoms

    International Nuclear Information System (INIS)

    Dietz, K.; Weymans, G.

    1983-09-01

    Renormalised g-Hartree-Dirac equations incorporating Dirac sea contributions are derived. Their implications for the non-perturbative, selfconsistent calculation of quantum corrections in large Z atoms are discussed. (orig.)

  11. Atomic spectrum of neptunium

    International Nuclear Information System (INIS)

    Fred, M.; Tomkins, F.S.; Blaise, J.E.; Camus, P.; Verges, J.

    1976-05-01

    A description and interpretation of the atomic spectrum of neptunium are given. Wavelengths were measured for 6096 spectrum lines in the range 3793 to 38,812 cm -1 (26,353 to 2575 A), of which 2526 were classified as transitions between 329 odd levels and 130 even levels of neutral neptunium (Np I). The data are presented in five tables

  12. Atoms in Astronomy.

    Science.gov (United States)

    Blanchard, Paul A.

    This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. A Basic Topics section discusses atomic structure, emphasizing states of matter at high temperature and spectroscopic analysis of light from the stars. A section…

  13. FAC: Flexible Atomic Code

    Science.gov (United States)

    Gu, Ming Feng

    2018-02-01

    FAC calculates various atomic radiative and collisional processes, including radiative transition rates, collisional excitation and ionization by electron impact, energy levels, photoionization, and autoionization, and their inverse processes radiative recombination and dielectronic capture. The package also includes a collisional radiative model to construct synthetic spectra for plasmas under different physical conditions.

  14. Deep diode atomic battery

    International Nuclear Information System (INIS)

    Anthony, T.R.; Cline, H.E.

    1977-01-01

    A deep diode atomic battery is made from a bulk semiconductor crystal containing three-dimensional arrays of columnar and lamellar P-N junctions. The battery is powered by gamma rays and x-ray emission from a radioactive source embedded in the interior of the semiconductor crystal

  15. Atomic transport properties

    International Nuclear Information System (INIS)

    Freyss, M.

    2015-01-01

    As presented in the first chapter of this book, atomic transport properties govern a large panel of nuclear fuel properties, from its microstructure after fabrication to its behaviour under irradiation: grain growth, oxidation, fission product release, gas bubble nucleation. The modelling of the atomic transport properties is therefore the key to understanding and predicting the material behaviour under irradiation or in storage conditions. In particular, it is noteworthy that many modelling techniques within the so-called multi-scale modelling scheme of materials make use of atomic transport data as input parameters: activation energies of diffusion, diffusion coefficients, diffusion mechanisms, all of which are then required to be known accurately. Modelling approaches that are readily used or which could be used to determine atomic transport properties of nuclear materials are reviewed here. They comprise, on the one hand, static atomistic calculations, in which the migration mechanism is fixed and the corresponding migration energy barrier is calculated, and, on the other hand, molecular dynamics calculations and kinetic Monte-Carlo simulations, for which the time evolution of the system is explicitly calculated. (author)

  16. The atomic society

    International Nuclear Information System (INIS)

    Hallerbach, J.; Hinz, M.O.; Huebner, H.; Huelsmann, H.; Krusewitz, K.; Mechels, E.; Moneta, J.; Mossmann, W.; Reuleaux, F.

    1978-01-01

    Nuclear power and social progress. Analyses and alternative. Organisation and development of the electric power industry. Conflicts in trade unions and churches. Processes of learning in court and in the science business. Materials, data, and figures on the development of power machinery and international atomic policy. Songs of the anti-nuclear movement. (orig.) [de

  17. Observational Evidence for Atoms.

    Science.gov (United States)

    Jones, Edwin R., Jr.; Childers, Richard L.

    1984-01-01

    Discusses the development of the concept of atomicity and some of the many which can be used to establish its validity. Chemical evidence, evidence from crystals, Faraday's law of electrolysis, and Avogadro's number are among the areas which show how the concept originally developed from a purely philosophical idea. (JN)

  18. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    Santoso, Budi; Arumbinang, Haryono.

    1981-01-01

    Emission spectra of alkali atoms has been determined by using spectrometer at the ultraviolet to infra red waves range. The spectra emission can be obtained by absorption spectrophotometric analysis. Comparative evaluations between experimental data and data handbook obtained by spark method were also presented. (author tr.)

  19. Experimental atomic physics

    International Nuclear Information System (INIS)

    Sellin, I.A.; Elston, S.B.; Forester, J.P.; Liao, K.H.; Pegg, D.J.; Peterson, R.S.; Thoe, R.S.; Hayden, H.C.; Griffin, P.M.

    1976-01-01

    The atomic structure and collision phenomena of highly stripped ions in the range Z = 6 to 35 were studied. Charge-transfer and multiple-electron-loss cross sections were determined. Absolute x-ray-production cross sections for incident heavy ions were measured. 10 figures, 1 table

  20. Atomic Particle Detection

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1970-01-01

    This booklet tells how scientists observe the particles and electromagnetic radiation that emerges from an atomic nucleus. The equipment used falls into two general categories: counters which count each particle as it passes by, and track detectors, which make a photographic record of the particle's track.

  1. Monte Carlo modeling of atomic oxygen attack of polymers with protective coatings on LDEF

    Science.gov (United States)

    Banks, Bruce A.; Degroh, Kim K.; Auer, Bruce M.; Gebauer, Linda; Edwards, Jonathan L.

    1993-01-01

    Characterization of the behavior of atomic oxygen interaction with materials on the Long Duration Exposure Facility (LDEF) assists in understanding of the mechanisms involved. Thus the reliability of predicting in-space durability of materials based on ground laboratory testing should be improved. A computational model which simulates atomic oxygen interaction with protected polymers was developed using Monte Carlo techniques. Through the use of an assumed mechanistic behavior of atomic oxygen interaction based on in-space atomic oxygen erosion of unprotected polymers and ground laboratory atomic oxygen interaction with protected polymers, prediction of atomic oxygen interaction with protected polymers on LDEF was accomplished. However, the results of these predictions are not consistent with the observed LDEF results at defect sites in protected polymers. Improved agreement between observed LDEF results and predicted Monte Carlo modeling can be achieved by modifying of the atomic oxygen interactive assumptions used in the model. LDEF atomic oxygen undercutting results, modeling assumptions, and implications are presented.

  2. General Atomic's radioactive gas recovery system

    International Nuclear Information System (INIS)

    Mahn, J.A.; Perry, C.A.

    1975-01-01

    General Atomic Company has developed a Radioactive Gas Recovery System for the HTGR which separates, for purposes of retention, the radioactive components from the non-radioactive reactor plant waste gases. This provides the capability for reducing to an insignificant level the amount of radioactivity released from the gas waste system to the atmosphere--a most significant improvement in reducing total activity release to the environment. (U.S.)

  3. Philippine Atomic Energy Commission: Annual report 1982

    International Nuclear Information System (INIS)

    1983-02-01

    This publication enumerates the research and development activities of the Philippine Atomic Energy Commission with priorities geared towards achieving the economic and social upliftment of the Filipinos in the field of agriculture, energy, industry, health and environment. Highlights are summaries of investigations and studies of great importance in crop improvement, animal production, nuclear fuels, nutrition research, not to mention its supportive technology, technical services, nuclear information and public acceptance, and nuclear manpower development. (RTD)

  4. Role of atoms in atomic gravitational-wave detectors

    Science.gov (United States)

    Norcia, Matthew A.; Cline, Julia R. K.; Thompson, James K.

    2017-10-01

    Recently, it has been proposed that space-based atomic sensors may be used to detect gravitational waves. These proposals describe the sensors either as clocks or as atom interferometers. Here, we seek to explore the fundamental similarities and differences between the two types of proposals. We present a framework in which the fundamental mechanism for sensitivity is identical for clock and atom interferometer proposals, with the key difference being whether or not the atoms are tightly confined by an external potential. With this interpretation in mind, we propose two major enhancements to detectors using confined atoms, which allow for an enhanced sensitivity analogous to large momentum transfer used in atom interferometry (though with no transfer of momentum to the atoms), and a way to extend the useful coherence time of the sensor beyond the atom's excited-state lifetime.

  5. Ionization of highly excited atoms by atomic particle impact

    International Nuclear Information System (INIS)

    Smirnov, B.M.

    1976-01-01

    The ionization of a highly excited atom by a collision with an atom or molecule is considered. The theory of these processes is presented and compared with experimental data. Cross sections and ionization potential are discussed. 23 refs

  6. Absorption imaging of ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Smith, David A.; Aigner, Simon; Hofferberth, Sebastian

    2011-01-01

    Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present...... methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions....

  7. Angular momentum coupling in atom-atom collisions

    International Nuclear Information System (INIS)

    Grosser, J.

    1986-01-01

    The coupling between the electronic angular momentum and the rotating atom-atom axis in the initial or the final phase of an atom-atom collision is discussed, making use of the concepts of radial and rotational (Coriolis) coupling between different molecular states. The description is based on a limited number of well-understood approximations, and it allows an illustrative geometric representation of the transition from the body fixed to the space fixed motion of the electrons. (orig.)

  8. Observing Planets and Small Bodies in Sputtered High Energy Atom (SHEA) Fluxes

    Science.gov (United States)

    Milillo, A.; Orsini, S.; Hsieh, K. C.; Baragiola, R.; Fama, M.; Johnson, R.; Mura, A.; Plainaki, Ch.; Sarantos, M.; Cassidy, T. A.; hide

    2012-01-01

    The evolution of the surfaces of bodies unprotected by either strong magnetic fields or thick atmospheres in the Solar System is caused by various processes, induced by photons, energetic ions and micrometeoroids. Among these processes, the continuous bombardment of the solar wind or energetic magnetospheric ions onto the bodies may significantly affect their surfaces, with implications for their evolution. Ion precipitation produces neutral atom releases into the exosphere through ion sputtering, with velocity distribution extending well above the particle escape limits. We refer to this component of the surface ejecta as sputtered high-energy atoms (SHEA). The use of ion sputtering emission for studying the interaction of exposed bodies (EB) with ion environments is described here. Remote sensing in SHEA in the vicinity of EB can provide mapping of the bodies exposed to ion sputtering action with temporal and mass resolution. This paper speculates on the possibility of performing remote sensing of exposed bodies using SHEA The evolution of the surfaces of bodies unprotected by either strong magnetic fields or thick atmospheres in the Solar System is caused by various processes, induced by photons, energetic ions and micrometeoroids. Among these processes, the continuous bombardment of the solar wind or energetic magnetospheric ions onto the bodies may significantly affect their surfaces, with implications for their evolution. Ion precipitation produces neutral atom releases into the exosphere through ion sputtering, with velocity distribution extending well above the particle escape limits. We refer to this component of the surface ejecta as sputtered high-energy atoms (SHEA). The use of ion sputtering emission for studying the interaction of exposed bodies (EB) with ion environments is described here. Remote sensing in SHEA in the vicinity of EB can provide mapping of the bodies exposed to ion sputtering action with temporal and mass resolution. This paper

  9. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    Science.gov (United States)

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  10. Atomic Act amended

    International Nuclear Information System (INIS)

    Drabova, D.

    2002-01-01

    In the paper by the chairwoman of the Czech nuclear regulatory authority, the history of Czech nuclear legislation is outlined, the reasons for the amendment of the Atomic Act (Act No. 18/1997) are explained, and the amendments themselves are highlighted. The Act No. 13/2002 of 18 December 2001 is reproduced from the official Collection of Acts of the Czech Republic in the facsimile form. The following acts were thereby amended: Atomic Act No. 18/1997, Metrology Act No. 505/1990, Public Health Protection Act No. 258/2000, and Act No. 2/1969 on the Establishment of Ministries and Other Governmental Agencies of the Czech Republic. (P.A.)

  11. Atomic assistance in 1961

    International Nuclear Information System (INIS)

    1961-01-01

    More than 100 experts provided by the International Atomic Energy Agency will be working in different parts of the world this year, assisting the Agency's Member States in building up their national programs of peaceful atomic development. The total allocation of EPTA funds to the Agency for the two-year period 1961-62 is $1 393 600 (of which approximately half is available in 1961), and is meant not only for the provision of experts and equipment but also for training fellowships and regional projects. The countries which will receive Agency assistance in the form of experts and equipment this year are: Afghanistan, Argentina, Austria, Brazil, Burma, Ceylon, Chile, the Republic of China, Denmark, Greece, Guatemala, Iceland, Indonesia, Iran, Iraq, Israel, Japan, the Republic of Korea, the Republic of Mali, Mexico, Morocco, Pakistan, the Philippines, Senegal, the Sudan, Thailand, Tunisia, Turkey, the United Arab Republic, Vietnam and Yugoslavia

  12. Atomicity for XML Databases

    Science.gov (United States)

    Biswas, Debmalya; Jiwane, Ashwin; Genest, Blaise

    With more and more data stored into XML databases, there is a need to provide the same level of failure resilience and robustness that users have come to expect from relational database systems. In this work, we discuss strategies to provide the transactional aspect of atomicity to XML databases. The main contribution of this paper is to propose a novel approach for performing updates-in-place on XML databases, with the undo statements stored in the same high level language as the update statements. Finally, we give experimental results to study the performance/storage trade-off of the updates-in-place strategy (based on our undo proposal) against the deferred updates strategy to providing atomicity.

  13. Elementary relativistic atoms

    International Nuclear Information System (INIS)

    Nemenov, L.

    2001-01-01

    The Coulomb interaction which occurs in the final state between two particles with opposite charges allows for creation of the bound state of these particles. In the case when particles are generated with large momentum in lab frame, the Lorentz factors of the bound state will also be much larger than one. The relativistic velocity of the atoms provides the opportunity to observe bound states of (π + μ - ), (π + π - ) and (π + K - ) with a lifetime as short as 10 -16 s, and to measure their parameters. The ultrarelativistic positronium atoms (A 2e ) allow us to observe the e.ect of superpenetration in matter, to study the effects caused by the formation time of A 2e from virtual e + e - pairs and to investigate the process of transformation of two virtual particles into the bound state

  14. Atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Haswell, S.J.

    1991-01-01

    Atomic absorption spectroscopy is now well established and widely used technique for the determination of trace and major elements in a wide range analyte types. There have been many advances in the atomic spectroscopy over the last decade and for this reason and to meet the demand, it was felt that there was a need for an updated book. Whilst interest in instrumental design has tended to dominate the minds of the spectrocopist, the analyst concerned with obtaining reliable and representative data, in diverse areas of application, has been diligently modifying and developing sample treatment and instrumental introduction techniques. Such methodology is de fundamental part of analysis and form the basis of the fourteen application chapters of this book. The text focuses in the main on AAS; however, the sample handling techniques described are in many cases equally applicable to ICP-OES and ICP-MS analysis. (author). refs.; figs.; tabs

  15. Atomic emission spectroscopy

    Science.gov (United States)

    Andrew, K. H.

    1975-01-01

    The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

  16. Glossary of atomic terms

    International Nuclear Information System (INIS)

    1980-01-01

    This glossary (of about 400 terms) has been compiled to help people outside the atomic energy industry to understand what those inside it are saying. It is not intended to be a definitive dictionary of scientific or technical terms, nor does it aim to cover terms that are in general use in science and technology. A list of some initials and acronyms is appended. (author)

  17. Glossary of atomic terms

    International Nuclear Information System (INIS)

    1982-04-01

    This glossary, containing almost 400 terms, has been compiled to help people outside the atomic energy industry to understand what those inside it are saying. It is not intended to be a definitive dictionary of scientific or technical terms, nor does it aim to cover terms that are in general use in science and technology. A list of about 100 initials and acronyms will be found at the end. (author)

  18. Atomic and molecular theory

    International Nuclear Information System (INIS)

    Inokuti, Mitio.

    1990-01-01

    The multifaceted role of theoretical physics in understanding the earliest stages of radiation action is discussed. Scientific topics chosen for the present discourse include photoabsorption, electron collisions, and ionic collisions, and electron transport theory, Connections of atomic and molecular physics with condensed-matter physics are also discussed. The present article includes some historical perspective and an outlook for the future. 114 refs., 3 figs

  19. Atomic physics issues in fusion

    International Nuclear Information System (INIS)

    Post, D.E.

    1982-01-01

    Atomic physics issues have played a large role in controlled fusion research. A general introduction to the present role of atomic processes in both inertial and magnetic controlled fusion work is presented. (Auth.)

  20. Real and Hybrid Atomic Orbitals.

    Science.gov (United States)

    Cook, D. B.; Fowler, P. W.

    1981-01-01

    Demonstrates that the Schrodinger equation for the hydrogenlike atom separates in both spheroconal and prolate spheroidal coordinates and that these separations provide a sound theoretical basis for the real and hybrid atomic orbitals. (Author/SK)

  1. Electromagnetic trapping of cold atoms

    International Nuclear Information System (INIS)

    Balykin, V.I.; Minogin, V.G.; Letokhov, V.S.

    2000-01-01

    This review describes the methods of trapping cold atoms in electromagnetic fields and in the combined electromagnetic and gravity fields. We discuss first the basic types of the dipole radiation forces used for cooling and trapping atoms in the laser fields. We outline next the fundamentals of the laser cooling of atoms and classify the temperature limits for basic laser cooling processes. The main body of the review is devoted to discussion of atom traps based on the dipole radiation forces, dipole magnetic forces, combined dipole radiation-magnetic forces, and the forces combined of the dipole radiation-magnetic and gravity forces. Physical fundamentals of atom traps operating as waveguides and cavities for cold atoms are also considered. The review ends with the applications of cold and trapped atoms in atomic, molecular and optical physics. (author)

  2. Physics of atoms and molecules

    International Nuclear Information System (INIS)

    Bransden, B.H.; Joachain, C.J.

    1983-01-01

    This book presents a unified account of the physics of atoms and molecules at a level suitable for second- and third-year undergraduate students of physics and physical chemistry. Following a brief historical introduction to the subject the authors outline the ideas and approximation methods of quantum mechanics to be used later in the book. Six chapters look at the structure of atoms and the interactions between atoms and electromagnetic radiation. The authors then move on to describe the structure of molecules and molecular spectra. Three chapters deal with atomic collisions, the scattering of electrons by atoms and the scattering of atoms by atoms. The concluding chapter considers a few of the many important applications of atomic physics within astrophysics, laser technology, and nuclear fusion. Problems are given at the end of each chapter, with hints at the solutions in an appendix. Other appendices include various special topics and derivations together with useful tables of units. (author)

  3. Atomic inner-shell physics

    International Nuclear Information System (INIS)

    Crasemann, B.

    1985-01-01

    This book discusses: relativistic and quantum electrodynamic effects on atomic inner shells; relativistic calculation of atomic transition probabilities; many-body effects in energetic atomic transitions; Auger Electron spectrometry of core levels of atoms; experimental evaluation of inner-vacancy level energies for comparison with theory; mechanisms for energy shifts of atomic K-X rays; atomic physics research with synchrotron radiation; investigations of inner-shell states by the electron energy-loss technique at high resolution; coherence effects in electron emission by atoms; inelastic X-ray scattering including resonance phenomena; Rayleigh scattering: elastic photon scattering by bound electrons; electron-atom bremsstrahlung; X-ray and bremsstrahlung production in nuclear reactions; positron production in heavy-ion collisions, and X-ray processes in heavy-ion collisions

  4. Evaporative cooling of trapped atoms

    International Nuclear Information System (INIS)

    Ketterle, W.; Van Druten, N.J.

    1996-01-01

    This report discusses the following topics on evaporative cooling of trapped atoms: Theoretical models for evaporative cooling; the role of collisions for real atoms; experimental techniques and summary of evaporative cooling experiments. 166 refs., 6 figs., 3 tabs

  5. Into the atom and beyond

    CERN Multimedia

    1989-01-01

    Magnifying an atom to football pitch size. The dense nucleus, carrying almost all the atomic mass, is much smaller than the ball. The players (the electrons) would see something about the size of a marble!

  6. A new atomic model

    International Nuclear Information System (INIS)

    Petrescu, Florian Ion

    2012-01-01

    The movement of an electron around the atomic nucleus has today a great importance in many engineering fields. Electronics, aeronautics, micro and nanotechnology, electrical engineering, optics, lasers, nuclear power, computing, equipment and automation, telecommunications, genetic engineering, bioengineering, special processing, modern welding, robotics, energy and electromagnetic wave field is today only a few of the many applications of electronic engineering. This book presents, shortly, a new and original relation (20 and 20') who determines the radius with that, the electron is running around the nucleus of an atom. One utilizes, two times the Lorenz relation, the Niels Bohr generalized equation, and a mass relation, which was deduced from the kinematics energy relation written in two modes: classical and Coulombian. Equalizing the mass relation with Lorenz relation one obtains a form which is a relation between the squared electron speed (v 2 ) and the radius (r). The second relation between v 2 and r was obtained by equalizing the mass of Bohr equation and the mass of Lorenz relation. For a Bohr energetically level (n=a constant value), one determines now two energetically below levels, which form an electronic layer. The author realizes by this a new atomic model, or a new quantum theory, which explains the existence of electron-clouds without spin.Writing the kinematics energy relation in two modes, classical and Coulombian one determines a relation, from which explicitely the mass of the electron is determined.

  7. Australia's atomic conspiracy theory

    International Nuclear Information System (INIS)

    Binnie, A.

    2001-01-01

    The author questions claims by the Newcastle University historian Wayne Reynolds in his book 'Australia's Bid for the Bomb', that the impetus behind the Snowy Mountains Scheme was to provide a secure source of power for the enrichment of uranium and production of heavy water so that Australia could produce its own atomic bombs. Reynolds also argued that the Australian Atomic Energy Commission (AAEC) was set up so that Australia had a trained scientific workforce to produce plutonium for the bomb. While the book is well researched, Reynolds does not seem to understand the principles of basic science and engineering. After the Second World War, a manufacturing and industrial base with a skilled and trained workforce was needed so it could be converted to war or defence manufacturing when the need arose. This new manufacturing community would require electrical power to sustain it. Hydroelectricity and atomic energy could help provide these needs. Even though war was still raging, Prime Minister John Curtin looked ahead and set up a Department of Post-War Reconstruction. It was through this department that the Snowy Mountains Scheme would be established. Curtin did not live to see this. He died in 1945 but his successor, Ben Chifley, continued the vision. The author believes, an understanding of the science behind these developments and an appreciation of how how humans interact with each others when it comes to getting something they want is likely to give a more balanced view of the past

  8. Relativistic correlations in atoms

    International Nuclear Information System (INIS)

    Dietz, K.

    1987-01-01

    Atoms are particularly well-suited objects when it comes to testing certain concepts of many-body theories. They play a unique role in this respect because of two constructively interfering reasons: first of all, the laws describing the interactions of their constituents are the ones best known in all of Physics; secondly, their structure is comparatively simple and amenable to concise theoretical treatment. Because of these two reasons, physically motivated many-body approximation schemes, ordered in a systematic hierarchy of precision, can be carefully tested; discrepancies between theory and experiment are due to many-body effects and are never masked by uncertainties in the constituent-interaction (needless to say, the very small hadronic contributions to atomic structure is left out. Many-body effects in atoms are solely produced by the electron-electron interaction which derives from the laws of Quantum Electrodynamics or, in a very good approximation from the repulsive Coulomb potential; in the general nomenclature they are named correlations. The material is organized in two chapters: chapter 1 deals with a general introduction and discussion of g-Hartree mean-field theories, chapter 2 deals with applications. The role of vacuum fluctuations and deformations of the Dirac sea in a consistent construction of mean-fields is emphasized and their explicit form in the g-Hartree theory is given. 21 references, 5 figures, 3 tables

  9. New sources of cold atoms for atomic clocks

    International Nuclear Information System (INIS)

    Aucouturier, E.

    1997-01-01

    The purpose of this doctoral work is the realisation of new sources of cold cesium atoms that could be useful for the conception of a compact and high-performance atomic clock. It is based on experiences of atomic physics using light induced atomic manipulation. We present here the experiences of radiative cooling of atoms that have been realised at the Laboratoire de l'Horloge Atomique from 1993 to 1996. Firstly, we applied the techniques of radiative cooling and trapping of atoms in order to create a three-dimensional magneto-optical trap. For this first experience, we developed high quality laser sources, that were used for other experiments. We imagined a new configuration of trapping (two-dimensional magneto-optical trap) that was the basis for a cold atom source. This design gives the atoms a possibility to escape towards one particular direction. Then, we have extracted the atoms from this anisotropic trap in order to create a continuous beam of cold atoms. We have applied three methods of extraction. Firstly, the launching of atoms was performed by reducing the intensity of one of the cooling laser beams in the desired launching direction. Secondly, a frequency detuning between the two laser laser beams produced the launching of atoms by a so-called 'moving molasses'. The third method consisted in applying a static magnetic field that induced the launching of atoms in the direction of this magnetic field. At the same time, another research on cold atoms was initiated at the I.H.A. It consisted in cooling a large volume of atoms from a cell, using an isotropic light. This offers an interesting alternative to the traditional optical molasses. (author)

  10. Self-lacing atomic chains

    NARCIS (Netherlands)

    Zandvliet, Henricus J.W.; van Houselt, Arie; Poelsema, Bene

    2009-01-01

    The structural and electronic properties of self-lacing atomic chains on Pt modified Ge(001) surfaces have been studied using low-temperature scanning tunnelling microscopy and spectroscopy. The self-lacing chains have a cross section of only one atom, are perfectly straight, thousands of atoms long

  11. Atomic Energy Commission Act, 1963

    International Nuclear Information System (INIS)

    1963-01-01

    Promulgated in 1963, the Atomic Energy Commission Act (204) established and vested in the Ghana Atomic Energy Commission the sole responsibility for all matters relating to the peaceful uses of atomic energy in the country. Embodied in the Act are provisions relating to the powers, duties, rights and liabilities of the Commission. (EAA)

  12. Current Trends in Atomic Spectroscopy.

    Science.gov (United States)

    Wynne, James J.

    1983-01-01

    Atomic spectroscopy is the study of atoms/ions through their interaction with electromagnetic radiation, in particular, interactions in which radiation is absorbed or emitted with an internal rearrangement of the atom's electrons. Discusses nature of this field, its status and future, and how it is applied to other areas of physics. (JN)

  13. Breaking the atom with Samson

    NARCIS (Netherlands)

    Väänänen, J.; Coecke, B.; Ong, L.; Panangaden, P.

    2013-01-01

    The dependence atom =(x,y) was introduced in [11]. Here x and y are finite sets of attributes (or variables) and the intuitive meaning of =(x,y) is that the attributes x completely (functionally) determine the attributes y. One may wonder, whether the dependence atom is truly an atom or whether it

  14. Polarizational radiation or 'atomic' bremsstrahlung

    International Nuclear Information System (INIS)

    Ya Amusia, M.

    1992-01-01

    It is demonstrated that a new kind of continuum spectrum radiation exists, where the mechanism of formation is quite different from that of ordinary bremsstrahlung. The latter originates due to slowing down of the charged projectile in the target field, while the former, called polarization radiation or 'atomic' bremsstrahlung, is a result of radiation either of the target or the projectile particles dipolarly polarized during the collision process. Not only general formulae, but also results of concrete calculations are presented. These demonstrate, that for electron-atom collisions the atomic contribution to the total bremsstrahlung spectrum becomes dominant for photon energies near and above the atomic ionization potential. As to atom-atom or ion-atom collisions, the bremsstrahlung spectrum is completely determined by the atomic contribution. The specific features of the case when the incoming particles are relativistic are discussed at length. A number of examples of colliding pairs are considered, for which the atomic bremsstrahlung process is quite essential: A bare nucleus and an atom, pair of atoms, at least one of which is excited, electron, or atom interacting with a molecule. The same mechanism is essential also in formation of radiation in nuclear and elementary particle collisions. (orig.)

  15. Measurement of Local Gravity via a Cold Atom Interferometer

    International Nuclear Information System (INIS)

    Zhou Lin; Xiong Zong-Yuan; Yang Wei; Tang Biao; Peng Wen-Cui; Wang Yi-Bo; Xu Peng; Wang Jin; Zhan Ming-Sheng

    2011-01-01

    We demonstrate a precision measurement of local gravity acceleration g in Wuhan by a compact cold atom interferometer. The atom interferometer is in vertical Mach—Zehnder configuration realized using a π/2 - π - π/2 Raman pulse sequence. Cold atoms were prepared in a magneto-optical trap, launched upward to form an atom fountain, and then coherently manipulated to interfere by stimulated Raman transition. Population signal vs Raman laser phase was recorded as interference fringes, and the local gravity was deduced from the interference signal. We have obtained a resolution of 7 × 10 −9 g after an integration time of 236s under the best vibrational environment conditions. The absolute g value was derived from the chirp rate with a difference of 1.5 × 10 −7 g compared to the gravity reference value. The tidal phenomenon was observed by continuously monitoring the local gravity over 123 h. (atomic and molecular physics)

  16. On correspondence between atomic volume and atomic radius in metals

    International Nuclear Information System (INIS)

    Malyuchkov, O.T.

    1980-01-01

    Atomic radii for 68 metals and their allotropic modifications are calculated according to proposed carlier technique for recalculation of real structure to structures with coordination number 12. The comparison of obtained values with published data confirms the supposition on proportionality of the dependence between atomic volume and atomic radius. Atomic number is more sensitive to structural transformations than atomic radius and it can better characterize a tendency in electronic structure modification of a substance during phase transistions. Taking into considerations that in different structure modifications both the value of atomic volume and the correlation between the volume of ''rigid ball'' and peripherical part of atomic volume change, these changes can be used for qualitative assesment of a number of parameters of electronic structure of metals, alloys and compounds [ru

  17. Influence Business Environment On The Organization Performance

    OpenAIRE

    Ridwan Ibrahim; Ina Primiana

    2015-01-01

    Abstract The purpose of this study was to find solutions for problems related to the organization performance when connected with business environment. This study was theoretical review especially about the effect of business environment on the organization performance. The results showed that business environment have a significant effect on organizatio performance. Furthermore it was found that business environment has implication for organization performance.

  18. An Introduction to Atomic Layer Deposition with Thermal Applications

    Science.gov (United States)

    Dwivedi, Vivek H.

    2015-01-01

    Atomic Layer Deposition (ALD) is a cost effective nano-manufacturing technique that allows for the conformal coating of substrates with atomic control in a benign temperature and pressure environment. Through the introduction of paired precursor gases thin films can be deposited on a myriad of substrates ranging from glass, polymers, aerogels, and metals to high aspect ratio geometries. This talk will focus on the utilization of ALD for engineering applications.

  19. Liquid-Arc/Spark-Excitation Atomic-Emission Spectroscopy

    Science.gov (United States)

    Schlagen, Kenneth J.

    1992-01-01

    Constituents of solutions identified in situ. Liquid-arc/spark-excitation atomic-emission spectroscopy (LAES) is experimental variant of atomic-emission spectroscopy in which electric arc or spark established in liquid and spectrum of light from arc or spark analyzed to identify chemical elements in liquid. Observations encourage development of LAES equipment for online monitoring of process streams in such industries as metal plating, electronics, and steel, and for online monitoring of streams affecting environment.

  20. Human factors in atomic power plant

    International Nuclear Information System (INIS)

    Kawano, Ryutaro

    1997-01-01

    To ensure safety should have priority over all other things in atomic power plants. In Chernobyl accident, however, various human factors including the systems for bulb check after inspection and communication, troubles in the interface between hardwares such as warning speakers and instruments, and their operators, those in education and training for operators and those in the general management of the plant have been pointed out. Therefore, the principles and the practical measures from the aspect of human factors in atomic power plants were discussed here. The word, ''human factor'' was given a definition in terms of the direct cause and the intellectual system. An explanatory model for human factors, model SHEL constructed by The Tokyo Electric Power Co., Ltd., Inc. was presented; the four letter mean software(S), hardware(H), environment(E) and liveware(L). In the plants of the company, systemic measures for human error factors are taken now in all steps not only for design, operation and repairing but also the step for safety culture. Further, the level required for the safety against atomic power is higher in the company than those in other fields. Thus, the central principle in atomic power plants is changing from the previous views that technology is paid greater importance to a view regarding human as most importance. (M.N.)