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Sample records for atomic number revisited

  1. The effective atomic number revisited in the light of modern photon-interaction cross-section databases

    International Nuclear Information System (INIS)

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K.S.; Gerward, L.

    2010-01-01

    The effective atomic number, Z eff , has been calculated for fatty acids and cysteine. It is shown that Z eff is a useful parameter for low-Z materials at any energy above 1 keV. Absorption edges of medium-Z elements may complicate the energy dependence of Z eff below 10 keV. The notion of Z eff is perhaps most useful at energies where Compton scattering is dominating, and where Z eff is equal to the mean atomic number, , over a wide energy range around 1 MeV.

  2. The effective atomic number revisited in the light of modern photon-interaction cross-section databases

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K. S.

    2010-01-01

    The effective atomic number, Z(eff), has been calculated for fatty acids and cysteine. It is shown that Z(eff) is a useful parameter for low-Z materials at any energy above 1 key. Absorption edges of medium-Z elements may complicate the energy dependence of Z(eff) below 10 key. The notion of Z......(eff) is perhaps most useful at energies where Compton scattering is dominating, and where Z(eff) is equal to the mean atomic number, , over a wide energy range around 1 MeV....

  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. Electronic structure of super heavy atoms revisited

    International Nuclear Information System (INIS)

    Gitman, D M; Levin, A D; Tyutin, I V; Voronov, B L

    2013-01-01

    The electronic structure of an atom with Z ⩽ Z c = 137 can be described by the Dirac equation with the Coulomb field of a point charge Ze. It was believed that the Dirac equation with Z > Z c poses difficulties because the formula for the lower energy level of the Dirac Hamiltonian formally gives imaginary eigenvalues. But a strict mathematical consideration shows that difficulties with the electronic spectrum for Z > Z c do not arise if the Dirac Hamiltonian is correctly defined as a self-adjoint operator. In this paper, we briefly summarize the main physical results of that consideration in a form suitable for physicists with some additional new details and numerical calculations of the electronic spectra. (comment)

  5. Effective atomic number of dental smalt

    International Nuclear Information System (INIS)

    Rodas D, J.E.; Nogueira, M.S.

    1998-01-01

    The effective atomic numbers Z are enough utilized for to characterize the interactions of ionizing radiation with matter. Particularly for the Z calculation in biological tissues and/or composed materials we need to know the relationship between the cross sections of the diverse radiations interactions with mattera and the atomic numbers Z of the constituent elements in the tissue or composed material. Normally the cross section by atom σ 2 is proportional to Z m . The m value depends of the iterative process type and the energy of the incident photons. In the case of the photoelectric interaction, the m vary will vary between 4,698 and 4,799 for energies between 10 to 200 keV. It was verified that constituent elements with high Z (>20) they had a major contribution. The m values for the Compton interation and the coherent scattering were calculated of similar way. Knowing the m values, we calculate the partials Z of a composed material. For the calculation of total Z, we can use alternatives starting from the equivalent atomic number corresponding to the total cross section σ d tot, mc of the composed material. In this work for the calculation of Z values corresponding to diverse interations, we applied a linear regression at the values of Ln σ a x LnZ for different energies. In general, to characterize a simulator material of a tissue or composed material we need to know the total Z in function of the photon energy applied to dental smalt increases until some hundreds of keV the partial values of Z owing to photoelectric effect and the coherent scattering this is owing to the smalt has a great concentration of elements with high Z. (Author)

  6. Investigation of systematic errors of metastable "atomic pair" number

    CERN Document Server

    Yazkov, V

    2015-01-01

    Sources of systematic errors in analysis of data, collected in 2012, are analysed. Esti- mations of systematic errors in a number of “atomic pairs” fr om metastable π + π − atoms are presented.

  7. Determination numbers of ionized atoms from emission and absorption lines

    International Nuclear Information System (INIS)

    Alizadeh Azimi, A.; Shokouhi, N.

    2002-01-01

    Saha, M., (1920) estimated that salter chromosphere is not only due to radiation from neutral atoms, but from ionized atoms. The failure to observe these stellar lines in the laboratory was attributed to internal temperature and pressure about 10* E + 6 K 10* E-7 atm. In this research we found that emission lines of ionized atoms (like Cs) could be measured in laboratory condition, (about 10* E-3 atm and 2000 K) by using Graphite France Atomic Absorption with injection 124 u g C sel. We calculated the numbers of ionized atoms from Bottzman law. We also measured these numbers from area under the energy-time curve

  8. Operator entanglement of two-qubit joint unitary operations revisited: Schmidt number approach

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Hui-Zhi; Li, Chao; Yang, Qing; Yang, Ming, E-mail: mingyang@ahu.edu.cn [Key Laboratory of Opto-electronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Material Science, Anhui University Hefei (China); Cao, Zhuo-Liang [School of Electronic Information Engineering, Hefei Normal University (China)

    2012-08-15

    The operator entanglement of two-qubit joint unitary operations is revisited. The Schmidt number, an important attribute of a two-qubit unitary operation, may have connection with the entanglement measure of the unitary operator. We find that the entanglement measure of a two-qubit unitary operators is classified by the Schmidt number of the unitary operators. We also discuss the exact relation between the operator entanglement and the parameters of the unitary operator. (author)

  9. Photon mass attenuation coefficients, effective atomic numbers and ...

    Indian Academy of Sciences (India)

    of atomic number Z was performed using the logarithmic regression analysis of the data measured by the authors and reported earlier. The best-fit coefficients so obtained in the photon ..... This photon build-up is a function of thickness and atomic number of the sample and also the incident photon energy, which combine to ...

  10. Accessing photon number via an atomic time interval

    International Nuclear Information System (INIS)

    Camparo, J.C.; Coffer, J.G.

    2002-01-01

    We show that Rabi resonances can be used to assess field strength in terms of time at the atomic level. Rabi resonances are enhancements in the amplitude of atomic population oscillations when the Rabi frequency, Ω, 'matches' a field-modulation frequency, ω m . We demonstrate that Ω=2κω m and find that κ=1.03±0.05. Since Ω is defined by field strength (i.e., photon number) through atomic constants, and ω m may be referenced to an atomic clock, our work shows that Rabi resonances provide a connection between time and photon number

  11. q-Bernoulli numbers and q-Bernoulli polynomials revisited

    Directory of Open Access Journals (Sweden)

    Kim Taekyun

    2011-01-01

    Full Text Available Abstract This paper performs a further investigation on the q-Bernoulli numbers and q-Bernoulli polynomials given by Acikgöz et al. (Adv Differ Equ, Article ID 951764, 9, 2010, some incorrect properties are revised. It is point out that the generating function for the q-Bernoulli numbers and polynomials is unreasonable. By using the theorem of Kim (Kyushu J Math 48, 73-86, 1994 (see Equation 9, some new generating functions for the q-Bernoulli numbers and polynomials are shown. Mathematics Subject Classification (2000 11B68, 11S40, 11S80

  12. A versatile atomic number correction for electron-probe microanalysis

    International Nuclear Information System (INIS)

    Love, G.; Cox, M.G.; Scott, V.D.

    1978-01-01

    A new atomic number correction is proposed for quantitative electron-probe microanalysis. Analytical expressions for the stopping power S and back-scatter R factors are derived which take into account atomic number of the target, incident electron energy and overvoltage; the latter expression is established using Monte Carlo calculations. The correct procedures for evaluating S and R for multi-element specimens are described. The new method, which overcomes some limitations inherent in earlier atomic number corrections, may readily be used where specimens are inclined to the electron beam. (author)

  13. General displaced SU(1, 1) number states: Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Dehghani, A., E-mail: alireza.dehghani@gmail.com, E-mail: a-dehghani@tabrizu.ac.ir [Physics Department, Payame Noor University, P.O. Box 19395-3697 Tehran (Iran, Islamic Republic of)

    2014-04-15

    The most general displaced number states, based on the bosonic and an irreducible representation of the Lie algebra symmetry of su(1, 1) and associated with the Calogero-Sutherland model are introduced. Here, we utilize the Barut-Girardello displacement operator instead of the Klauder-Perelomov counterpart, to construct new kind of the displaced number states which can be classified in nonlinear coherent states regime, too, with special nonlinearity functions. They depend on two parameters, and can be converted into the well-known Barut-Girardello coherent and number states, respectively, depending on which of the parameters equal to zero. A discussion of the statistical properties of these states is included. Significant are their squeezing properties and anti-bunching effects which can be raised by increasing the energy quantum number. Depending on the particular choice of the parameters of the above scenario, we are able to determine the status of compliance with flexible statistics. Major parts of the issue is spent on something that these states, in fact, should be considered as new kind of photon-added coherent states, too. Which can be reproduced through an iterated action of a creation operator on new nonlinear Barut-Girardello coherent states. Where the latter carry, also, outstanding statistical features.

  14. The Atomic Number Revolution in Chemistry: A Kuhnian Analysis

    DEFF Research Database (Denmark)

    Wray, K. Brad

    2018-01-01

    This paper argues that the field of chemistry underwent a significant change of theory in the early twentieth century, when atomic number replaced atomic weight as the principle for ordering and identifying the chemical elements. It is a classic case of a Kuhnian revolution. In the process of add...

  15. Thomas-Fermi theory for atomic nuclei revisited

    International Nuclear Information System (INIS)

    Centelles, M.; Schuck, P.; Vinas, X.

    2007-01-01

    The recently developed semiclassical variational Wigner-Kirkwood (VWK) approach is applied to finite nuclei using external potentials and self-consistent mean fields derived from Skyrme interactions and from relativistic mean field theory. VWK consists of the Thomas-Fermi part plus a pure, perturbative h 2 correction. In external potentials, VWK passes through the average of the quantal values of the accumulated level density and total energy as a function of the Fermi energy. However, there is a problem of overbinding when the energy per particle is displayed as a function of the particle number. The situation is analyzed comparing spherical and deformed harmonic oscillator potentials. In the self-consistent case, we show for Skyrme forces that VWK binding energies are very close to those obtained from extended Thomas-Fermi functionals of h 4 order, pointing to the rapid convergence of the VWK theory. This satisfying result, however, does not cure the overbinding problem, i.e., the semiclassical energies show more binding than they should. This feature is more pronounced in the case of Skyrme forces than with the relativistic mean field approach. However, even in the latter case the shell correction energy for e.g., 208 Pb turns out to be only ∼-6 MeV what is about a factor two or three off the generally accepted value. As an ad hoc remedy, increasing the kinetic energy by 2.5%, leads to shell correction energies well acceptable throughout the periodic table. The general importance of the present studies for other finite Fermi systems, self-bound or in external potentials, is pointed out

  16. Revisited

    DEFF Research Database (Denmark)

    Tegtmeier, Silke; Meyer, Verena; Pakura, Stefanie

    2017-01-01

    were captured when they described entrepreneurs. Therefore, this paper aims to revisit gender role stereotypes among young adults. Design/methodology/approach: To measure stereotyping, participants were asked to describe entrepreneurs in general and either women or men in general. The Schein......Purpose: Entrepreneurship is shaped by a male norm, which has been widely demonstrated in qualitative studies. The authors strive to complement these methods by a quantitative approach. First, gender role stereotypes were measured in entrepreneurship. Second, the explicit notions of participants......: The images of men and entrepreneurs show a high and significant congruence (r = 0.803), mostly in those adjectives that are untypical for men and entrepreneurs. The congruence of women and entrepreneurs was low (r = 0.152) and insignificant. Contrary to the participants’ beliefs, their explicit notions did...

  17. Stabilization of atoms with nonzero magnetic quantum numbers

    International Nuclear Information System (INIS)

    Sundaram, B.; Jensen, R.V.

    1993-01-01

    A classical analysis of the interaction of an atomic electron with an oscillating electric field with arbitrary initial quantum number, n, magnetic quantum number, m > 0, field strength, and frequency shows that the classical, dynamics for the perturbed electron can be stabilized for large fields and high frequencies. Using a four-dimensional map approximation to the classical dynamics, explicit expressions are obtained for the full parameter dependence of the boundaries of stability surrounding the open-quotes death valleyclose quotes of rapid classical ionization. A preliminary analysis of the quantum dynamics in terms of the quasienergy states associated with the corresponding quantum map is also included with particular emphasis on the role of unstable classical structures in stabilizing atoms. Together, these results provide motivation and direction for further theoretical and experimental studies of stabilization of atoms (and molecules) in super-intense microwave and laser fields

  18. Simulated mixed absorbers and effective atomic numbers for γ ...

    Indian Academy of Sciences (India)

    The total -ray interaction crosss-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for -ray absorption under narrow beam good geometry set-up. The measurements were taken for the combination of metallic absorbers like aluminium, copper, lead and mercury ...

  19. Effective atomic number, electron density and kerma of gamma ...

    Indian Academy of Sciences (India)

    Abstract. An attempt has been made to estimate the effective atomic number, electron density (0.001 to 105 MeV) and kerma (0.001 to 20 MeV) of gamma radiation for a wide range of oxides of ... The lanthanide oxides find remarkable applications in the field of medicine, biology, nuclear engineering and space technology.

  20. Determination of atomic number and composition of human enamel

    International Nuclear Information System (INIS)

    Nogueira, M.S.; Rodas Duran, J.E.

    2001-01-01

    The teeth are organs of complicated structure that consist, partly, of hard tissue containing in its interior the dental pulp, rich in vases and nerves. The main mass of the tooth is constituted by the dentine, which is covered with hard tissues and of epithelial origin called enamel. The dentine of the human teeth used in this work were completely removed and the teeth were cut with a device with a diamond disc. In this work the chemical composition of the human enamel was determined, which showed a high percentage of Ca and P, in agreement with the results found in the literature. The effective atomic number of the material and the half-value layer in the energy range of diagnostic X-ray beams were determined. Teeth could be used to evaluated the public's individual doses as well as for retrospective dosimetry what confirms the importance of their effective atomic number and composition determination. (author)

  1. Successive change regularity of actinide properties with atomic number

    International Nuclear Information System (INIS)

    Yang Xuexian

    1990-08-01

    The development and achievements on chemistry of actinide elements are summarised. The relations of properties of actinides to their electronic configurations of valence electronic shells are discussed. Some anomalies of solid properties, the radius contraction, the stable state effect of f 7n -orbits (n = 0, 1, 2) and the tetrad effect of oxidation states, etc., with atomic number (Z) are described. 31 figures appended show directly the successive change regularity of actinide properties with Z

  2. Effective atomic number and electron density of marble concrete

    International Nuclear Information System (INIS)

    Akkurt, I.; El-Khayatt, A.M.

    2013-01-01

    The effective atomic numbers (Z eff ) and effective electron density (N e ) of different type concrete have been measured and the results were compared with the calculation obtained using the mass attenuation coefficients (μ/ρ) obtained via XCOM in the photon energy range of 1 keV-100 GeV. Six different concrete in where marble has been used in the rate of 0, 5, 10, 15, 20, 25 %, has been used in the study. (author)

  3. Synthesis of a New Element with Atomic Number Z=117

    International Nuclear Information System (INIS)

    Oganessian, Yu. Ts.; Abdullin, F. Sh.; Dmitriev, S. N.; Itkis, M. G.; Lobanov, Yu. V.; Mezentsev, A. N.; Polyakov, A. N.; Sagaidak, R. N.; Shirokovsky, I. V.; Subbotin, V. G.; Sukhov, A. M.; Tsyganov, Yu. S.; Utyonkov, V. K.; Voinov, A. A.; Vostokin, G. K.; Bailey, P. D.; Benker, D. E.; Ezold, J. G.; Porter, C. E.; Riley, F. D.

    2010-01-01

    The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293 117 and 294 117 were produced in fusion reactions between 48 Ca and 249 Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z≥111, validating the concept of the long sought island of enhanced stability for superheavy nuclei.

  4. Effective atomic numbers and electron density of dosimetric material

    Directory of Open Access Journals (Sweden)

    Kaginelli S

    2009-01-01

    Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

  5. A practical relation between atomic numbers and alpha coefficients

    International Nuclear Information System (INIS)

    Lachance, G.R.

    1980-01-01

    A first approximation indicates that fundamental alpha coefficients for a given analyte vary as a function of the ratio of their respective atomic number raised to a power. This simple rule applies mainly at the limits (i.e., when the weight fraction of analyte i, Wsub(i) is of the order of 0.0 or 1.0) in cases of absorption and weak enhancement. The relation thus provides a means of generating coefficients for the system i-k from experimental data obtained on system i-j and a means of verifying experimental alphas, since arrays of coefficients must show a high degree of concordance. (author)

  6. Low atomic number coating for XEUS silicon pore optics

    DEFF Research Database (Denmark)

    Lumb, D.H.; Cooper-Jensen, Carsten P.; Krumrey, M.

    2008-01-01

    We describe a set of measurements on coated silicon substrates that are representative of the material to be used for the XEUS High Performance Pore Optics (HPO) technology. X-ray angular reflectance measurements at 2.8 and 8 keV, and energy scans of reflectance at a fixed angle representative...... of XEUS graze angles are presented. Reflectance is significantly enhanced for low energies when a low atomic number over-coating is applied. Modeling of the layer thicknesses and roughness is used to investigate the dependence on the layer thicknesses, metal and over coat material choices. We compare...

  7. Low atomic number coating for XEUS silicon pore optics

    Science.gov (United States)

    Lumb, D. H.; Jensen, C. P.; Krumrey, M.; Cibik, L.; Christensen, F.; Collon, M.; Bavdaz, M.

    2008-07-01

    We describe a set of measurements on coated silicon substrates that are representative of the material to be used for the XEUS High Performance Pore Optics (HPO) technology. X-ray angular reflectance measurements at 2.8 and 8 keV, and energy scans of reflectance at a fixed angle representative of XEUS graze angles are presented. Reflectance is significantly enhanced for low energies when a low atomic number over-coating is applied. Modeling of the layer thicknesses and roughness is used to investigate the dependence on the layer thicknesses, metal and over coat material choices. We compare the low energy effective area increase that could be achieved with an optimized coating design.

  8. Revisiting magnetism of capped Au and ZnO nanoparticles: Surface band structure and atomic orbital with giant magnetic moment

    Energy Technology Data Exchange (ETDEWEB)

    Hernando, Antonio; Crespo, Patricia [Instituto de Magnetismo Aplicado, UCM-CSIC-ADIF, Las Rozas. P.O. Box 155, 28230 Madrid (Spain); Dept. Fisica de Materiales, Universidad Complutense, Madrid (Spain); Garcia, Miguel Angel [Instituto de Ceramica y Vidrio, CSIC, C/ Kelsen, 5, Madrid 28049 (Spain); Coey, Michael [Trinity College Dublin, Dublin (Ireland); Ayuela, Andres; Echenique, Pedro Miguel [Centro de Fisica de Materiales, CFM-MPC CSIC-UPV/EHU, Donostia International Physics Center (DIPC), 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Fac. de Quimicas, Universidad del Pais Vasco UPV-EHU, 20018 San Sebastian (Spain)

    2011-10-15

    In this article we review the exotic magnetism of nanoparticles (NPs) formed by substances that are not magnetic in bulk as described with generality in Section 1. In particular, the intrinsic character of the magnetism observed on capped Au and ZnO NPs is analysed. X-ray magnetic circular dichroism (XMCD) analysis has shown that the magnetic moments are intrinsic and lie in the Au and Zn atoms, respectively, as analysed in Section 2, where the general theoretical ideas are also revisited. Since impurity atoms bonded to the surface act as donor or acceptor of electrons that occupy the surface states, the anomalous magnetic response is analysed in terms of the surface band in Section 3. Finally, Section 4 summarizes our last theoretical proposal. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. [Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

    Science.gov (United States)

    Zheng, Hui-jie; Quan, Wei; Liu, Xiang; Chen, Yao; Lu, Ji-xi

    2015-02-01

    High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

  10. Simulated mixed absorbers and effective atomic numbers for γ ...

    Indian Academy of Sciences (India)

    Keywords. γ-rays; γ attenuation; simulated mixed absorbers; effective atomic ... We have tried to simulate composite (mixed) absorbers ... Experimental method .... puter, Program manual, Centre for Radiation Research, National Bureau of ...

  11. Measurement of effective atomic number of composite materials using scattering of γ-rays

    International Nuclear Information System (INIS)

    Singh, M.P.; Sandhu, B.S.; Singh, Bhajan

    2007-01-01

    In the present experiment, to determine the effective atomic number of composite materials, the scattering of 145 keV γ-rays is studied using a high-resolution HPGe semiconductor detector placed at 70 deg. to the incident beam. The experiment is performed on various elements of different atomic number, 6≤Z≤64, for 145 keV incident photons. The intensity ratio of Rayleigh to Compton scattered peaks, corrected for photo-peak efficiency of the γ-detector and absorption of photons in the target and air, is plotted as a function of atomic number and constituted a fit curve. From this fit curve, the respective effective atomic numbers of the composite materials are determined. The agreement of measured values of effective atomic number with the theory is found to be quite satisfactory

  12. Effective atomic numbers of some tissue substitutes by different methods: A comparative study

    Directory of Open Access Journals (Sweden)

    Vishwanath P Singh

    2014-01-01

    Full Text Available Effective atomic numbers of some human organ tissue substitutes such as polyethylene terephthalate, red articulation wax, paraffin 1, paraffin 2, bolus, pitch, polyphenylene sulfide, polysulfone, polyvinylchloride, and modeling clay have been calculated by four different methods like Auto-Z eff, direct, interpolation, and power law. It was found that the effective atomic numbers computed by Auto-Z eff , direct and interpolation methods were in good agreement for intermediate energy region (0.1 MeV < E < 5 MeV where the Compton interaction dominates. A large difference in effective atomic numbers by direct method and Auto-Z eff was observed in photo-electric and pair-production regions. Effective atomic numbers computed by power law were found to be close to direct method in photo-electric absorption region. The Auto-Z eff , direct and interpolation methods were found to be in good agreement for computation of effective atomic numbers in intermediate energy region (100 keV < E < 10 MeV. The direct method was found to be appropriate method for computation of effective atomic numbers in photo-electric region (10 keV < E < 100 keV. The tissue equivalence of the tissue substitutes is possible to represent by any method for computation of effective atomic number mentioned in the present study. An accurate estimation of Rayleigh scattering is required to eliminate effect of molecular, chemical, or crystalline environment of the atom for estimation of gamma interaction parameters.

  13. Measurement of the effective atomic numbers of compounds with cerium near to the absorption edge

    International Nuclear Information System (INIS)

    Polat, Recep; Icelli, Orhan

    2010-01-01

    In order to measure atomic, molecular and electronic cross-section; the effective atomic number, density of electron and absorption jump factor, we have first measured μ t values of compounds which are determined by mixture rule using transmission method. In order to measure experimentally the effective atomic number within absorption jump factors of compounds with Ce, the X-ray source used Am-241 whose gamma rays were stopped at secondary source (Sm), thus producing Kα and Kβ X-ray emission. The most crucial finding in this study is that measurement of the effective atomic number is not appropriate near to the absorption edge and the effective atomic number is affected by near to the absorption edge. The results obtained have been compared with theoretical values.

  14. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

    International Nuclear Information System (INIS)

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-01-01

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green’s function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4p z atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices

  15. Metal-Insulator Transition Revisited for Cold Atoms in Non-Abelian Gauge Potentials

    International Nuclear Information System (INIS)

    Satija, Indubala I.; Dakin, Daniel C.; Clark, Charles W.

    2006-01-01

    We discuss the possibility of realizing metal-insulator transitions with ultracold atoms in two-dimensional optical lattices in the presence of artificial gauge potentials. For Abelian gauges, such transitions occur when the magnetic flux penetrating the lattice plaquette is an irrational multiple of the magnetic flux quantum. Here we present the first study of these transitions for non-Abelian U(2) gauge fields. In contrast to the Abelian case, the spectrum and localization transition in the non-Abelian case is strongly influenced by atomic momenta. In addition to determining the localization boundary, the momentum fragments the spectrum. Other key characteristics of the non-Abelian case include the absence of localization for certain states and satellite fringes around the Bragg peaks in the momentum distribution and an interesting possibility that the transition can be tuned by the atomic momenta

  16. Radio-isotopic apparatus for analyzing low atomic number elements by fluorescence

    International Nuclear Information System (INIS)

    Robert, Andre; Martinelli, Pierre; Daniel, Georges; Laflotte, Jean-Luc

    1969-10-01

    An apparatus is described for analyzing light elements of atomic number between 6 and 24 by X-fluorescence. The samples are excited by means of X or α isotopic sources. Various examples of analytical determinations are given. (author) [fr

  17. The method of intersecting spheres for determination of coordination numbers of atoms in crystal structures

    International Nuclear Information System (INIS)

    Serezhkin, V.N.; Buslaev, Yu.A.; Mikhajlov, Yu.N.

    1997-01-01

    New method for determination of coordination numbers (CN) of atoms in crystal structures, based on the model of interatomic interaction, within the frames whereof each atom is approximated by two spheres with the common center in the atom nuclei, is proposed. One of the spheres specifies conditionally isolated (chemically unbound) atom and its radius is a constant, which for atoms of the given chemical sort in the structure of any compound is equal to quasi-orbital Sleiter radius. The sphere of the other radius specifies chemically bound atom and coincides with the sphere, the volume whereof is equal to the volume of the Voronoj-Dirichlet polyhedron of the corresponding atom in the structure of the concrete crystal. Using a series of examples, workability of the given method for CN determination of atoms in structures of both simple substances and chemical compounds (alkali, transition metals, U, Th). Good agreement of the obtained results with the generally accepted CN s of atoms for the considered crystals is noted and a number of principal advantages of the new method, as compared to classical one of the CNs evaluation, is demonstrated

  18. Love, literature and the quantum atom Niels Bohr's 1913 trilogy revisited

    CERN Document Server

    Aaserud, Finn

    2013-01-01

    Niels Bohr ranks with Einstein among the physicists of the 20th century. He rose to this status through his invention of the quantum theory of the atom and his leadership in its defense and development. He also ranks with Einstein in his humanism and his sense of responsibility to his science and the society that enabled him to create it. Our book presents unpublished excerpts from extensive correspondence between Bohr and his immediate family, and uses it to describe and analyze the psychological and cultural background to his invention. The book also contains a reprinting of the three papers of 1913 - the "Trilogy" - in which Bohr worked out the provisional basis of a quantum theory of the atom.

  19. Atomic-scale structure of GeSe2 glass revisited: a continuous or broken network of Ge-(Se1/2)4 tetrahedra?

    International Nuclear Information System (INIS)

    Petkov, V; Le Messurier, D

    2010-01-01

    The atomic-scale structure of germanium diselenide (GeSe 2 ) glass has been revisited using a combination of high-energy x-ray diffraction and constrained reverse Monte Carlo simulations. The study shows that the glass structure may be very well described in terms of a continuous network of corner- and edge-sharing Ge-Se 4 tetrahedra. The result is in contrast to other recent studies asserting that the chemical order and, hence, network integrity in GeSe 2 glass are intrinsically broken. It is suggested that more elaborate studies are necessary to resolve the controversy.

  20. Revisiting the electrochemical impedance spectroscopy of magnesium with online inductively coupled plasma atomic emission spectroscopy.

    Science.gov (United States)

    Shkirskiy, Viacheslav; King, Andrew D; Gharbi, Oumaïma; Volovitch, Polina; Scully, John R; Ogle, Kevin; Birbilis, Nick

    2015-02-23

    The electrochemical impedance of reactive metals such as magnesium is often complicated by an obvious inductive loop with decreasing frequency of the AC polarising signal. The characterisation and ensuing explanation of this phenomenon has been lacking in the literature to date, being either ignored or speculated. Herein, we couple electrochemical impedance spectroscopy (EIS) with online atomic emission spectroelectrochemistry (AESEC) to simultaneously measure Mg-ion concentration and electrochemical impedance spectra during Mg corrosion, in real time. It is revealed that Mg dissolution occurs via Mg(2+) , and that corrosion is activated, as measured by AC frequencies less than approximately 1 Hz approaching DC conditions. The result of this is a higher rate of Mg(2+) dissolution, as the voltage excitation becomes slow enough to enable all Mg(2+) -enabling processes to adjust in real time. The manifestation of this in EIS data is an inductive loop. The rationalisation of such EIS behaviour, as it relates to Mg, is revealed for the first time by using concurrent AESEC. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Quantum phase crossovers with finite atom number in the Dicke model

    International Nuclear Information System (INIS)

    Hirsch, J G; Castaños, O; Nahmad-Achar, E; López-Peña, R

    2013-01-01

    Two-level atoms interacting with a one-mode cavity field at zero temperature have order parameters which reflect the presence of a quantum phase transition at a critical value of the atom–cavity coupling strength. Two popular examples are the number of photons inside the cavity and the number of excited atoms. Coherent states provide a mean field description, which becomes exact in the thermodynamic limit. Employing symmetry-adapted (SA) SU(2) coherent states the quantum crossover, precursor of the critical behavior, can be described for a finite number of atoms. A variation after projection treatment, involving a numerical minimization of the SA energy surface, associates the quantum crossover with a discontinuity in the order parameters, which originates from competition between two local minima in the SA energy surface. Although this discontinuity is not present in finite systems, it provides a good description of 1/N effects in the observables. (paper)

  2. A spectrometric approach in radiography for detection of materials by their effective atomic number

    CERN Document Server

    Ryzhikov, V D; Onyshchenko, G M; Lecoq, P; Smith, C F

    2009-01-01

    In this paper we report a spectrometric approach to dual-energy digital radiography that has been developed and applied to identify specific organic substances and discern small differences in their effective atomic number. An experimental setup has been designed, and a theoretical description proposed based on the experimental results obtained. The proposed method is based on the application of special reference samples made of materials with different effective atomic number and thickness parameters known to affect X-ray attenuation in the low-energy range. The results obtained can be used in the development of a new generation of multi-energy customs or medical X-ray scanners.

  3. Platinum clusters with precise numbers of atoms for preparative-scale catalysis.

    Science.gov (United States)

    Imaoka, Takane; Akanuma, Yuki; Haruta, Naoki; Tsuchiya, Shogo; Ishihara, Kentaro; Okayasu, Takeshi; Chun, Wang-Jae; Takahashi, Masaki; Yamamoto, Kimihisa

    2017-09-25

    Subnanometer noble metal clusters have enormous potential, mainly for catalytic applications. Because a difference of only one atom may cause significant changes in their reactivity, a preparation method with atomic-level precision is essential. Although such a precision with enough scalability has been achieved by gas-phase synthesis, large-scale preparation is still at the frontier, hampering practical applications. We now show the atom-precise and fully scalable synthesis of platinum clusters on a milligram scale from tiara-like platinum complexes with various ring numbers (n = 5-13). Low-temperature calcination of the complexes on a carbon support under hydrogen stream affords monodispersed platinum clusters, whose atomicity is equivalent to that of the precursor complex. One of the clusters (Pt 10 ) exhibits high catalytic activity in the hydrogenation of styrene compared to that of the other clusters. This method opens an avenue for the application of these clusters to preparative-scale catalysis.The catalytic activity of a noble metal nanocluster is tied to its atomicity. Here, the authors report an atom-precise, fully scalable synthesis of platinum clusters from molecular ring precursors, and show that a variation of only one atom can dramatically change a cluster's reactivity.

  4. The Fractions SNARC Revisited: Processing Fractions on a Consistent Mental Number Line.

    Science.gov (United States)

    Toomarian, Elizabeth Y; Hubbard, Edward M

    2017-07-12

    The ability to understand fractions is key to establishing a solid foundation in mathematics, yet children and adults struggle to comprehend them. Previous studies have suggested that these struggles emerge because people fail to process fraction magnitude holistically on the mental number line (MNL), focusing instead on fraction components (Bonato et al. 2007). Subsequent studies have produced evidence for default holistic processing (Meert et al., 2009; 2010), but examined only magnitude processing, not spatial representations. We explored the spatial representations of fractions on the MNL in a series of three experiments: Experiment 1 replicated Bonato et al. (2007); 30 naïve undergraduates compared unit fractions (1/1-1/9) to 1/5, resulting in a reverse SNARC effect. Experiment 2 countered potential strategic biases induced by the limited set of fractions used by Bonato et al. by expanding the stimulus set to include all irreducible, single-digit proper fractions, and asked participants to compare them against 1/2. We observed a classic SNARC effect, completely reversing the pattern from Experiment 1. Together, Experiments 1 and 2 demonstrate that stimulus properties dramatically impact spatial representations of fractions. In Experiment 3, we demonstrated within-subjects reliability of the SNARC effect across both a fractions and whole number comparison task. Our results suggest that adults can indeed process fraction magnitudes holistically, and that their spatial representations occur on a consistent MNL for both whole numbers and fractions.

  5. Nanoarchitectonics for Controlling the Number of Dopant Atoms in Solid Electrolyte Nanodots.

    Science.gov (United States)

    Nayak, Alpana; Unayama, Satomi; Tai, Seishiro; Tsuruoka, Tohru; Waser, Rainer; Aono, Masakazu; Valov, Ilia; Hasegawa, Tsuyoshi

    2018-02-01

    Controlling movements of electrons and holes is the key task in developing today's highly sophisticated information society. As transistors reach their physical limits, the semiconductor industry is seeking the next alternative to sustain its economy and to unfold a new era of human civilization. In this context, a completely new information token, i.e., ions instead of electrons, is promising. The current trend in solid-state nanoionics for applications in energy storage, sensing, and brain-type information processing, requires the ability to control the properties of matter at the ultimate atomic scale. Here, a conceptually novel nanoarchitectonic strategy is proposed for controlling the number of dopant atoms in a solid electrolyte to obtain discrete electrical properties. Using α-Ag 2+ δ S nanodots with a finite number of nonstoichiometry excess dopants as a model system, a theory matched with experiments is presented that reveals the role of physical parameters, namely, the separation between electrochemical energy levels and the cohesive energy, underlying atomic-scale manipulation of dopants in nanodots. This strategy can be applied to different nanoscale materials as their properties strongly depend on the number of doping atoms/ions, and has the potential to create a new paradigm based on controlled single atom/ion transfer. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Atom-number squeezing and bipartite entanglement of two-component Bose-Einstein condensates: analytical results

    Energy Technology Data Exchange (ETDEWEB)

    Jin, G R; Wang, X W; Li, D; Lu, Y W, E-mail: grjin@bjtu.edu.c [Department of Physics, Beijing Jiaotong University, Beijing 100044 (China)

    2010-02-28

    We investigate spin dynamics of a two-component Bose-Einstein condensate with weak Josephson coupling. Analytical expressions of atom-number squeezing and bipartite entanglement are presented for atom-atom repulsive interactions. For attractive interactions, there is no number squeezing; however, the squeezing parameter is still useful to recognize the appearance of Schroedinger's cat state.

  7. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2008-01-01

    The effective atomic number, Z(eff), the effective electron density, N-el, and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCo...

  8. Cheminoes: A Didactic Game to Learn Chemical Relationships between Valence, Atomic Number, and Symbol

    Science.gov (United States)

    Moreno, Luis F.; Hincapié, Gina; Alzate, María Victoria

    2014-01-01

    Cheminoes is a didactic game that enables the meaningful learning of some relations between concepts such as chemical element, valence, atomic number, and chemical symbol for the first 36 chemical elements of the periodic system. Among the students who have played the game, their opinions of the activity were positive, considering the game to be a…

  9. The effective atomic numbers of some biomolecules calculated by two methods: A comparative study

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2009-01-01

    The effective atomic numbers Z(eff) of some fatty acids and amino acids have been calculated by two numerical methods, a direct method and an interpolation method, in the energy range of 1 keV-20 MeV. The notion of Z(eff) is given a new meaning by using a modern database of photon interaction cro...

  10. An x ray scatter approach for non-destructive chemical analysis of low atomic numbered elements

    Science.gov (United States)

    Ross, H. Richard

    1993-01-01

    A non-destructive x-ray scatter (XRS) approach has been developed, along with a rapid atomic scatter algorithm for the detection and analysis of low atomic-numbered elements in solids, powders, and liquids. The present method of energy dispersive x-ray fluorescence spectroscopy (EDXRF) makes the analysis of light elements (i.e., less than sodium; less than 11) extremely difficult. Detection and measurement become progressively worse as atomic numbers become smaller, due to a competing process called 'Auger Emission', which reduces fluorescent intensity, coupled with the high mass absorption coefficients exhibited by low energy x-rays, the detection and determination of low atomic-numbered elements by x-ray spectrometry is limited. However, an indirect approach based on the intensity ratio of Compton and Rayleigh scattered has been used to define light element components in alloys, plastics and other materials. This XRS technique provides qualitative and quantitative information about the overall constituents of a variety of samples.

  11. The effective atomic numbers of some biomolecules calculated by two methods: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Manohara, S. R.; Hanagodimath, S. M.; Gerward, L. [Department of Physics, Gulbarga University, Gulbarga, Karnataka 585 106 (India); Department of Physics, Technical University of Denmark, Lyngby DK-2800 (Denmark)

    2009-01-15

    The effective atomic numbers Z{sub eff} of some fatty acids and amino acids have been calculated by two numerical methods, a direct method and an interpolation method, in the energy range of 1 keV-20 MeV. The notion of Z{sub eff} is given a new meaning by using a modern database of photon interaction cross sections (WinXCom). The results of the two methods are compared and discussed. It is shown that for all biomolecules the direct method gives larger values of Z{sub eff} than the interpolation method, in particular at low energies (1-100 keV) At medium energies (0.1-5 MeV), Z{sub eff} for both methods is about constant and equal to the mean atomic number of the material. Wherever possible, the calculated values of Z{sub eff} are compared with experimental data.

  12. The effective atomic numbers of some biomolecules calculated by two methods: A comparative study

    International Nuclear Information System (INIS)

    Manohara, S. R.; Hanagodimath, S. M.; Gerward, L.

    2009-01-01

    The effective atomic numbers Z eff of some fatty acids and amino acids have been calculated by two numerical methods, a direct method and an interpolation method, in the energy range of 1 keV-20 MeV. The notion of Z eff is given a new meaning by using a modern database of photon interaction cross sections (WinXCom). The results of the two methods are compared and discussed. It is shown that for all biomolecules the direct method gives larger values of Z eff than the interpolation method, in particular at low energies (1-100 keV) At medium energies (0.1-5 MeV), Z eff for both methods is about constant and equal to the mean atomic number of the material. Wherever possible, the calculated values of Z eff are compared with experimental data.

  13. Maximum compression of Z-pinch in a gas with high atomic number

    International Nuclear Information System (INIS)

    Gerusov, A.V.

    1989-01-01

    An ideal system of equations with shock heating is used for describing of a Z pinch in a gas with high atomic number. In this case equations do not depend from the installation parameters. The approximate simple solution of such a system is presented. Numerical calculations of equations with radiative cooling and various dissipative effects have determined the employment conditions of ideal magnetohydrodynamic equation system. 10 refs

  14. Effective atomic numbers, electron densities and kinetic energy released in matter of vitamins for photon interaction

    Science.gov (United States)

    Shantappa, A.; Hanagodimath, S. M.

    2014-01-01

    Effective atomic numbers, electron densities of some vitamins (Retinol, Riboflavin, Niacin, Biotin, Folic acid, Cobalamin, Phylloquinone and Flavonoids) composed of C, H, O, N, Co, P and S have been calculated for total and partial photon interactions by the direct method for energy range 1 keV-100 GeV by using WinXCOM and kinetic energy released in matter (Kerma) relative to air is calculated in energy range of 1 keV-20 MeV. Change in effective atomic number and electron density with energy is calculated for all photon interactions. Variation of photon mass attenuation coefficients with energy are shown graphically only for total photon interaction. It is observed that change in mass attenuation coefficient with composition of different chemicals is very large below 100 keV and moderate between 100 keV and 10 MeV and negligible above 10 MeV. Behaviour of vitamins is almost indistinguishable except biotin and cobalamin because of large range of atomic numbers from 1(H) to 16 (S) and 1(H) to 27(Co) respectively. K a value shows a peak due to the photoelectric effect around K-absorption edge of high- Z constituent of compound for biotin and cobalamin.

  15. Improved atom number with a dual color magneto—optical trap

    International Nuclear Information System (INIS)

    Cao Qiang; Luo Xin-Yu; Gao Kui-Yi; Wang Xiao-Rui; Wang Ru-Quan; Chen Dong-Min

    2012-01-01

    We demonstrate a novel dual color magneto—optical trap (MOT), which uses two sets of overlapping laser beams to cool and trap 87 Rb atoms. The volume of cold cloud in the dual color MOT is strongly dependent on the frequency difference of the laser beams and can be significantly larger than that in the normal MOT with single frequency MOT beams. Our experiment shows that the dual color MOT has the same loading rate as the normal MOT, but much longer loading time, leading to threefold increase in the number of trapped atoms. This indicates that the larger number is caused by reduced light induced loss. The dual color MOT is very useful in experiments where both high vacuum level and large atom number are required, such as single chamber quantum memory and Bose—Einstein condensation (BEC) experiments. Compared to the popular dark spontaneous-force optical trap (dark SPOT) technique, our approach is technically simpler and more suitable to low power laser systems. (rapid communication)

  16. Experimental study of stopping powers for ions of intermediate atomic numbers

    International Nuclear Information System (INIS)

    Bucher, R.G.

    1975-01-01

    A technique has been developed to measure the energy loss as a function of ion atomic number for the fragments emitted by the spontaneous fission of 252 Cf; the atomic numbers of the fragments were directly measured by the detection of a characteristic K x-ray. The measured energy losses were compared with the theories of Lindhard and of Firsov, with the tabulation of Northcliffe and Schilling, and with the semiempirical formula of Moak and Brown. For the light fragments the measured values are in good agreement with the predictions of Moak--Brown and Northcliffe--Schilling; for the heavy fragments the measured values are approximately midway between the prediction of Moak--Brown and Northcliffe--Schilling and those of Lindhard for xi/sub epsilon/ = 2. The difference in the stopping powers for adjacent ion atomic numbers Z 1 was concluded to be (1.8 +- 0.2) percent for 40 less than or equal to Z 1 less than or equal to 45 at a velocity of 1.36 cm/ns and (2.0 +- 0.1) percent for 53 less than or equal to Z 1 less than or equal to 58 at a velocity of 1.04 cm/ns

  17. Effective atomic number of dental smalt; Numero atomico efetivo do esmalte dentario

    Energy Technology Data Exchange (ETDEWEB)

    Rodas D, J.E.; Nogueira, M.S. [Departamento de Fisica e Matematica da FFCLRP-USP. 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    1998-12-31

    The effective atomic numbers Z are enough utilized for to characterize the interactions of ionizing radiation with matter. Particularly for the Z calculation in biological tissues and/or composed materials we need to know the relationship between the cross sections of the diverse radiations interactions with mattera and the atomic numbers Z of the constituent elements in the tissue or composed material. Normally the cross section by atom {sigma} {sup 2} is proportional to Z{sup m}. The m value depends of the iterative process type and the energy of the incident photons. In the case of the photoelectric interaction, the m vary will vary between 4,698 and 4,799 for energies between 10 to 200 keV. It was verified that constituent elements with high Z (>20) they had a major contribution. The m values for the Compton interation and the coherent scattering were calculated of similar way. Knowing the m values, we calculate the partials Z of a composed material. For the calculation of total Z, we can use alternatives starting from the equivalent atomic number corresponding to the total cross section {sigma} {sup d} tot, mc of the composed material. In this work for the calculation of Z values corresponding to diverse interations, we applied a linear regression at the values of Ln {sigma} {sup a} x LnZ for different energies. In general, to characterize a simulator material of a tissue or composed material we need to know the total Z in function of the photon energy applied to dental smalt increases until some hundreds of keV the partial values of Z owing to photoelectric effect and the coherent scattering this is owing to the smalt has a great concentration of elements with high Z. (Author)

  18. Two-Dimensional SnO Anodes with a Tunable Number of Atomic Layers for Sodium Ion Batteries

    KAUST Repository

    Zhang, Fan; Zhu, Jiajie; Zhang, Daliang; Schwingenschlö gl, Udo; Alshareef, Husam N.

    2017-01-01

    We have systematically changed the number of atomic layers stacked in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB) performance. The results indicate that as the number of atomic SnO layers in a sheet decreases, both

  19. Comparison of effective atomic numbers of the cancerous and normal kidney tissue

    International Nuclear Information System (INIS)

    Manjunatha, H.C.

    2015-01-01

    The effective atomic number (Z eff ) and electron density (N e ) of normal kidney and cancerous kidney have been computed for total and partial photon interactions by computing the molecular, atomic, and electronic cross section in the wide energy range of 1 keV-100 GeV using WinXCOM. The mean Z eff and N e of normal kidney and cancerous kidney in the various energy ranges and for total and partial photon interactions are tabulated. The variation of effective N e with energy is shown graphically for all photon interactions. In addition to this computer tomography (CT), numbers of normal kidney and cancerous kidney for photon interaction and energy absorption is also computed. The role of Z eff in the dual-energy dividing radiography is also discussed. The values of Z eff and N e for cancerous kidney are higher than normal kidney. This is due to the levels of elements K, Ca, Fe, Ni, and Se are lower and those of the elements Ti, Co, Zn, As, and Cd are higher in the cancer tissue of kidney than those observed in the normal tissue. The soft tissue and cancerous tissue are very similar, but their atomic number differs. The cancerous tissue exhibits a higher Z eff than the normal tissue. This fact helps in the dual-energy dividing radiography which enables to improve the diagnosis of the kidney cancer. Hence, the computed values may be useful in the diagnosis of the kidney cancer. CT numbers for normal kidney are higher than cancerous kidney. (author)

  20. Fragmented metastable states exist in an attractive bose-einstein condensate for atom numbers well above the critical number of the Gross-Pitaevskii theory.

    Science.gov (United States)

    Cederbaum, Lorenz S; Streltsov, Alexej I; Alon, Ofir E

    2008-02-01

    It is well known that attractive condensates do not posses a stable ground state in three dimensions. The widely used Gross-Pitaevskii theory predicts the existence of metastable states up to some critical number N(cr)(GP) of atoms. It is demonstrated here that fragmented metastable states exist for atom numbers well above N(cr)(GP). The fragments are strongly overlapping in space. The results are obtained and analyzed analytically as well as numerically. The implications are discussed.

  1. The influence of atomic number on the complex formation constants by visible spectrophotometric method

    International Nuclear Information System (INIS)

    Samin; Kris-Tri-Basuki; Farida-Ernawati

    1996-01-01

    The influence of atomic number on the complex formation constants and it's application by visible spectrophotometric method has been carried out. The complex compound have been made of Y, Nd, Sm and Gd with alizarin red sulfonic in the mole fraction range of 0.20 - 0.53 and pH range of 3.5 - 5. The optimum condition of complex formation was found in the mole fraction range of 0.30 - 0.53, range of pH 3.75 - 5, and the total concentration was 0.00030 M. It was found that the formation constant (β) of alizarin red S. complex by continued variation and matrix disintegration techniques were β : (7.00 ± 0.64).10 9 of complex 3 9γ,β : (4.09±0.34).10 8 of 6 0Nd, β : (7.26 ± 0.42).10 8 of 62 S m and β : (8.38 ± 0.70).10 8 of 64 G d. It can be concluded that the atomic number of Nd is bigger than Sm which is bigger than Gd. The atomic number of Y is the smallest. (39) and the complex formation constant is a biggest. The complex compound can be used for sample analysis with limit detection of Y : 2.2 .10 -5 M, Nd : 2.9 .10 -5 M, Sm : 2.6 .10 -5 M and Gd : 2.4 .10 -5 M. The sensitivity of analysis are Y>Gd>Sm>Nd. The Y 2 O 3 sample of product result from xenotime sand contains Y 2 O 3 : 98.96 ± 1.40 % and in the filtrate (product of monazite sand) contains Nd : 0.27 ± 0.002 M

  2. Efficiency of ablative plasma energy transfer into a massive aluminum target using different atomic number ablators

    Czech Academy of Sciences Publication Activity Database

    Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Stepniewski, W.; Jach, K.; Swierczynski, R.; Renner, Oldřich; Šmíd, Michal; Ullschmied, Jiří; Cikhart, J.; Klír, D.; Kubeš, P.; Řezáč, K.; Krouský, Eduard; Pfeifer, Miroslav; Skála, Jiří

    2015-01-01

    Roč. 33, č. 3 (2015), s. 379-386 ISSN 0263-0346 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk(CZ) LD14089 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; AVČR(CZ) M100101208 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : ablator atomic number * crater volume * laser energy transfer * plasma ablative pressure Subject RIV: BL - Plasma and Gas Discharge Physics; BH - Optics, Masers, Lasers (UFP-V) Impact factor: 1.649, year: 2015

  3. The effective atomic number for gamma ray interactions with heavy metal oxide glasses

    DEFF Research Database (Denmark)

    Manohara, S. R.; Hanagodimath, S.M.; Gerward, Leif

    2010-01-01

    The effective atomic number, Z(eff), and the effective electron density, N-el,N-eff, have been calculated at photon energies from 1 keV to 100 GeV for CaO-SrO-B2O3, ZnO-PbO-B2O3, and CdO-PbO-B2O3 glasses with potential applications as gamma ray shielding materials. Appreciable variations are noted...... glasses have gamma ray shielding properties comparable with standard shielding materials, such as concrete....

  4. Mechanical properties of cancer cells depend on number of passages: Atomic force microscopy indentation study

    Science.gov (United States)

    Dokukin, Maxim E.; Guz, Natalia V.; Sokolov, Igor

    2017-08-01

    Here we investigate one of the key questions in cell biology, if the properties of cell lines depend on the number of passages in-vitro. It is generally assumed that the change of cell properties (phenotypic drift) is insignificant when the number of passages is low (cell body and parameters of the pericellular brush layer from indentation force curves, which are recorded by means of atomic force microscopy (AFM). Using this method, we tested the change of the cell properties of human cancer breast epithelial cell line, MCF-7 (ATCC® HTB-22™), within the passages between 2 and 10. In contrast to the previous expectations, we observed a substantial transient change of the elastic modulus of the cell body during the first four passages (up to 4 times). The changes in the parameters of the pericellular coat were less dramatic (up to 2 times) but still statistically significant.

  5. Electron density and effective atomic number (Zeff) determination through x-ray Moiré deflectometry

    Science.gov (United States)

    Valdivia Leiva, Maria Pia; Stutman, Dan; Finkenthal, Michael

    2014-10-01

    Talbot-Lau based Moiré deflectometry is a powerful density diagnostic capable of delivering refraction information and attenuation from a single image, through the accurate detection of X-ray phase-shift and intensity. The technique is able to accurately measure both the real part of the index of refraction δ (directly related to electron density) and the attenuation coefficient μ of an object placed in the x-ray beam. Since the atomic number Z (or Zeff for a composite sample) is proportional to these quantities, an elemental map of the effective atomic number can be obtained with the ratio of the phase and the absorption image. The determination of Zeff from refraction and attenuation measurements with Moiré deflectometry could be of high interest in various fields of HED research such as shocked materials and ICF experiments as Zeff is linked, by definition, to the x-ray absorption properties of a specific material. This work is supported by U.S. DoE/NNSA Grant No. 435 DENA0001835.

  6. Advances in low atomic number element analysis by wavelength dispersive x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Vrebos, B.

    1996-01-01

    Traditionally, the analysis of low atomic number has been a chal1enging task for wavelength dispersive x-ray fluorescence spectrometry. Among the most important factors influencing analysis of the low atomic number elements (from Z=11 downwards) are the fluorescence yield, absorption and the dispersion. The effect of each of these factors on the overall performance will be illustrated. The long wavelengths involved (longer than I nm) used to pose severe problems concerning the monochromator used. Early instruments relied on lead stearate or Blodgett Langmuir soap films for the diffraction of the characteristic radiation. Nowadays, synthetic multilayers are commonly used. The performance of these multilayers is determined by the reflectivity, the resolution and the absorption of the characteristic radiation to be diffracted. These parameters can be optimised by adequately selecting the composition of the materials involved. The sensitivity of the modem instruments is sufficient to allow quantitative analysis. However, this aspect of WDS XRF is still met with considerable scepticism. Examples of quantitative analysis will be given to illustrate the current capability

  7. Effective atomic numbers (Z_e_f_f) of based calcium phosphate biomaterials: a comparative study

    International Nuclear Information System (INIS)

    Fernandes Zenobio, Madelon Aparecida; Gonçalves Zenobio, Elton; Silva, Teógenes Augusto da; Socorro Nogueira, Maria do

    2016-01-01

    This study determined the interaction of radiation parameters of four biomaterials as attenuators to measure the transmitted X-rays spectra, the mass attenuation coefficient and the effective atomic number by spectrometric system comprising the CdTe detector. The biomaterial BioOss"® presented smaller mean energy than the other biomaterials. The μ/ρ and Z_e_f_f of the biomaterials showed their dependence on photon energy. The data obtained from analytical methods of x-ray spectra, µ/ρ and Z_e_f_f_, using biomaterials as attenuators, demonstrated that these materials could be used as substitutes for dentin, enamel and bone. Further, they are determinants for the characterization of the radiation in tissues or equivalent materials. - Highlights: • Measure of the transmitted x-rays spectra using based calcium phosphate biomaterials as attenuators. • Determination effective atomic number using four dental biomaterials. • Determination of the mass attenuation coefficient (µ/ρ) of the biomaterials samples calculated by the WinXCOM software. • Determination of the chemical composition of calcium phosphate biomaterials.

  8. Calculation of radiation attenuation coefficients, effective atomic numbers and electron densities for some building materials

    International Nuclear Information System (INIS)

    Damla, N.; Baltas, H.; Celik, A.; Kiris, E.; Cevik, U.

    2008-01-01

    Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass attenuation coefficient, effective atomic, numbers (Z eff ), effective electron densities (N e ) and photon interaction cross section (σ a ) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass attenuation coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass attenuation coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory. (authors)

  9. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    International Nuclear Information System (INIS)

    Manohara, S R; Hanagodimath, S M; Gerward, L

    2008-01-01

    The effective atomic number, Z eff , the effective electron density, N el , and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. The significant variation of Z eff and N el is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z eff and N el are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Z eff and N el are found at intermediate energies, typically 0.05 MeV eff is equal to the mean atomic number of the bio-molecule. Wherever possible, the calculations are compared with experimental results. A comparison is also made with the single values of the Z eff and N el provided by the program XMuDat. It is also observed that carbohydrates have a larger kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the MeV range, where Compton scattering is the main interaction process. (note)

  10. Calculation of the number of atoms displaced during the irradiation of monolayer graphene

    International Nuclear Information System (INIS)

    Daniel Codorniu Pujals; Yuri Aguilera Corrales; Francesco Baldassarre

    2011-01-01

    The irradiation of monolayer graphene, combined with chemical functionalization, could be an effective method for modifying its electronic structure and for achieving specific physical properties adjusted to different applications. A difficulty arising during planning and studying the irradiation in this system is that many of the models of interaction of the radiation with the substance cannot be applied to the two-dimensional structure of graphene. In particular, the mathematical expressions available to calculate the number of atoms displaced during the bombardment with particles can be applied only to 3D isotropic solids. In the present work, an alternative analytic expression is presented for the irradiation of graphene with heavy ions or with protons and other light charged particles. The expression was obtained on the basis of the classic theory of dispersion, using a Coulomb potential for the light charged particles and one of Inverse Square for heavy ions. For medium values of the energy of the incident particle a decreasing dependence of the number of displaced atoms with energy is obtained. This behavior, related with the two-dimensional structure of the target, had been observed in other authors' works using computational simulation. (author)

  11. Critical radius and critical number of gas atoms for cavities containing a Van der Waals gas

    International Nuclear Information System (INIS)

    Coghlan, W.A.; Mansur, L.K.

    1983-01-01

    The effect of gas on void nucleation and growth is particularly important for structural materials in fusion reactors because of the high production of helium by neutron-induced transmutation reactions. Gas reduces the critical radius for bias driven growth and there is a critical number of gas atoms, n/sub g/*, at which the critical radius is reduced essentially to zero. The significance of this is that the time interval to the accumulation of n/sub g/* gas atoms may determine the time to the onset of bias driven swelling where n/sub g/* is large. In previous papers these critical quantities were given for an ideal gas. Recently, we presented the results for a Van der Waals gas. Here the derivation of these relations is presented and further results of calculations are given. At low temperatures (high pressures) the results depart from those of the ideal gas, with the critical number affected more strongly than the critical radius. Comparisons are made with earlier calculations

  12. System and process for determining the basis weight of a low atomic number material in a mixture with a higher atomic number material

    International Nuclear Information System (INIS)

    Hegland, P.; Dahlquist, J.

    1985-01-01

    A process for determining the relative quantity of low atomic energy material mixed with a higher atomic energy material is carried out by directing a first and second beam of x-rays into the mixture. The process includes transmitting x-rays directly to detectors to set one criterion, shielding the detectors from the x-ray sources to set another criterion and then passing samples of known relative composition to provide data for storage and calibration carrying out the process of mixtures to be measured

  13. 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)

  14. Combustor exhaust-emissions and blowout-limits with diesel number 2 and Jet A fuels utilizing air-atomizing and pressure-atomizing nozzles

    Science.gov (United States)

    Ingebo, R. D.; Norgren, C. T.

    1975-01-01

    The effect of fuel properties on exhaust emissions and blowout limits of a high-pressure combustor segment is evaluated using a splash-groove air-atomizing fuel injector and a pressure-atomizing simplex fuel nozzle to burn both diesel number 2 and Jet A fuels. Exhaust emissions and blowout data are obtained and compared on the basis of the aromatic content and volatility of the two fuels. Exhaust smoke number and emission indices for oxides of nitrogen, carbon monoxide, and unburned hydrocarbons are determined for comparison. As compared to the pressure-atomizing nozzle, the air-atomizing nozzle is found to reduce nitrogen oxides by 20%, smoke number by 30%, carbon monoxide by 70%, and unburned hydrocarbons by 50% when used with diesel number 2 fuel. The higher concentration of aromatics and lower volatility of diesel number 2 fuel as compared to Jet A fuel appears to have the most detrimental effect on exhaust emissions. Smoke number and unburned hydrocarbons are twice as high with diesel number 2 as with Jet A fuel.

  15. Systematic measurements of opacity dependence on temperature, density, and atomic number at stellar interior conditions

    Science.gov (United States)

    Nagayama, Taisuke

    2017-10-01

    Model predictions for iron opacity are notably different from measurements performed at matter conditions similar to the boundary between the solar radiation and convection zones. The calculated iron opacities have narrower spectral lines, weaker quasi-continuum at short wavelength, and deeper opacity windows than the measurements. If correct, these measurements help resolve a decade old problem in solar physics. A key question is therefore: What is responsible for the model-data discrepancy? The answer is complex because the experiments are challenging and opacity theories depend on multiple entangled physical processes such as the influence of completeness and accuracy of atomic states, line broadening, contributions from myriad transitions from excited states, and multi-photon absorption processes. To help determine the cause of this discrepancy, a systematic study of opacity variation with temperature, density, and atomic number is underway. Measurements of chromium, iron, and nickel opacities have been performed at two different temperatures and densities. The collection of measured opacities provides constraints on hypotheses to explain the discrepancy. We will discuss implications of measured opacities, experimental errors, and possible opacity model refinements. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

  16. Concept of effective atomic number and effective mass density in dual-energy X-ray computed tomography

    International Nuclear Information System (INIS)

    Bonnin, Anne; Duvauchelle, Philippe; Kaftandjian, Valérie; Ponard, Pascal

    2014-01-01

    This paper focuses on dual-energy X-ray computed tomography and especially the decomposition of the measured attenuation coefficient in a mass density and atomic number basis. In particular, the concept of effective atomic number is discussed. Although the atomic number is well defined for chemical elements, the definition of an effective atomic number for any compound is not an easy task. After reviewing different definitions available in literature, a definition related to the method of measurement and X-ray energy, is suggested. A new concept of effective mass density is then introduced in order to characterize material from dual-energy computed tomography. Finally, this new concept and definition are applied on a simulated case, focusing on explosives identification in luggage

  17. Modification of diode characteristics by electron back-scatter from high-atomic-number anodes

    International Nuclear Information System (INIS)

    Mosher, D.; Cooperstein, G.; Rose, D.V.; Swanekamp, S.B.

    1996-01-01

    In high-power vacuum diodes with high-atomic-number anodes, back-scattered electrons alter the vacuum space charge and resulting electron and ion currents. Electron multiple back-scattering was studied through equilibrium solutions of the Poisson equation for 1-dimensional, bipolar diodes in order to predict their early-time behavior. Before ion turn-on, back-scattered electrons from high-Z anodes suppress the diode current by about 10%. After ion turn-on in the same diodes, electron back-scatter leads to substantial enhancements of both the electron and ion currents above the Child-Langmuir values. Current enhancements with ion flow from low-Z anodes are small. (author). 5 figs., 7 refs

  18. X-ray spectrum determination of elements with low atomic number with use of electron microscope

    International Nuclear Information System (INIS)

    Smirnov, V.N.

    1982-01-01

    Separate assemblies of a commercial analytical electron microscope-microanalyzer EMMA-2 have been modified to study objects, containing elements with the atomic number Z=5-9, in particular: 1) the range of changing the accelerating voltages is expanded to be in the range of 25 down to 10 kV with 5 kV interval. 2) image intensifier using microchannel plate MKP-40-19 is applied; 3) for elements of carbon, oxygen, boron, nitrogen type a unit with flow-type proportional counter is used. The sensitivity of carbon- and oxygen determination in carbides and oxides is 0.15-0.3% at the measurement time of 100 s. Results of microanalysis of the particles of B 2 O 3 , Al 2 O 3 , SiO 2 , Fe 2 O 3 , Fe 3 C, WC for the contents of oxygen and carbon are presented

  19. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio

    Energy Technology Data Exchange (ETDEWEB)

    Antoniassi, M.; Conceicao, A.L.C. [Departamento de Fisica e Matematica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Poletti, M.E., E-mail: poletti@ffclrp.usp.br [Departamento de Fisica e Matematica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil)

    2011-10-01

    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90{sup o} (x=0.99 A{sup -1}). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number (Z{sub eff}) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Z{sub eff} of breast tissues, which are mainly related to the elemental composition of carbon (Z=6) and oxygen (Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  20. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio

    International Nuclear Information System (INIS)

    Antoniassi, M.; Conceicao, A.L.C.; Poletti, M.E.

    2011-01-01

    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90 o (x=0.99 A -1 ). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number (Z eff ) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Z eff of breast tissues, which are mainly related to the elemental composition of carbon (Z=6) and oxygen (Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  1. Methodology for attainment of density and effective atomic number through dual energy technique using microtomographic images

    International Nuclear Information System (INIS)

    Alves, H.; Lima, I.; Lopes, R.T.

    2014-01-01

    Dual energy technique for computerized microtomography shows itself as a promising method for identification of mineralogy on geological samples of heterogeneous composition. It can also assist with differentiating very similar objects regarding the attenuation coefficient, which are usually not separable during image processing and analysis of microtomographic data. Therefore, the development of a feasible and applicable methodology of dual energy in the analysis of microtomographic images was sought. - Highlights: • Dual energy technique is promising for identification of distribution of minerals. • A feasible methodology of dual energy in analysis of tomographic images was sought. • The dual energy technique is efficient for density and atomic number identification. • Simulation showed that the proposed methodology agrees with theoretical data. • Nondestructive characterization of distribution of density and chemical composition

  2. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio

    Science.gov (United States)

    Antoniassi, M.; Conceição, A. L. C.; Poletti, M. E.

    2011-10-01

    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90° ( x=0.99 Å -1). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number ( Zeff) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Zeff of breast tissues, which are mainly related to the elemental composition of carbon ( Z=6) and oxygen ( Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  3. Internal conversion coefficients for atomic numbers Z less than or equal to 30

    International Nuclear Information System (INIS)

    Band, I.M.; Trzhaskovskaya, M.B.; Listengarten, M.A.

    1976-01-01

    Presented here are internal conversion coefficients (ICC) of gamma rays for 20 values of atomic number, Z, in the range 3 less than or equal to Z less than or equal to 30, including all Z greater than or equal to 14. The tables provide the previously missing data for light elements. Coefficients are given for 19 values of gamma-ray transition energies up to 6 MeV for the K-electron shell and 18 values up to 2 MeV for three L-subshells. The minimum enegy is 15 keV. The first five electric and magnetic nuclear transition multipolarities are covered. The calculations are relativistic, with screening and finite nuclear size effect taken into account

  4. Modification of diode characteristics by electron back-scatter from high-atomic-number anodes

    Energy Technology Data Exchange (ETDEWEB)

    Mosher, D; Cooperstein, G [Naval Research Laboratory, Washington, DC (United States); Rose, D V; Swanekamp, S B [JAYCOR, Vienna, VA (United States)

    1997-12-31

    In high-power vacuum diodes with high-atomic-number anodes, back-scattered electrons alter the vacuum space charge and resulting electron and ion currents. Electron multiple back-scattering was studied through equilibrium solutions of the Poisson equation for 1-dimensional, bipolar diodes in order to predict their early-time behavior. Before ion turn-on, back-scattered electrons from high-Z anodes suppress the diode current by about 10%. After ion turn-on in the same diodes, electron back-scatter leads to substantial enhancements of both the electron and ion currents above the Child-Langmuir values. Current enhancements with ion flow from low-Z anodes are small. (author). 5 figs., 7 refs.

  5. Robust determination of effective atomic numbers for electron interactions with TLD-100 and TLD-100H thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    Taylor, M.L.

    2011-01-01

    Lithium fluoride thermoluminescent dosimeters (TLD) are the most commonly implemented for clinical dosimetry. The small physical magnitude of TLDs makes them attractive for applications such as small field measurement, in vivo dosimetry and measurement of out-of-field doses to critical structures. The most broadly used TLD is TLD-100 (LiF:Mg,Ti) and, for applications requiring higher sensitivity to low-doses, TLD-100H (LiF:Mg,Cu,P) is frequently employed. The radiological properties of these TLDs are therefore of significant interest. For the first time, in this study effective atomic numbers for radiative, collisional and total electron interaction processes are calculated for TLD-100 and TLD-100H dosimeters over the energy range 1 keV-100 MeV. This is undertaken using a robust, energy-dependent method of calculation rather than typical power-law approximations. The influence of dopant concentrations and unwanted impurities is also investigated. The two TLDs exhibit similar effective atomic numbers, ranging from approximately 5.77-6.51. Differences arising from the different dopants are most pronounced in low-energy radiative effects. The TLDs have atomic numbers approximately 1.48-2.06 times that of water. The effective atomic number of TLD-100H is consistently higher than that of TLD-100 over a broad energy range, due to the greater influence of the higher-Z dopants on the electron interaction cross sections. Typical variation in dopant concentration does not significantly influence the effective atomic number. The influence on TLD-100H is comparatively more pronounced than that on TLD-100. Contrariwise, unwanted hydroxide impurities influence TLD-100 more than TLD-100H. The effective atomic number is a key parameter that influences the radiological properties and energy response of TLDs. Although many properties of these TLDs have been studied rigorously, as yet there has been no investigation of their effective atomic numbers for electron interactions. The

  6. Radiation Build-Up Of High Energy Gamma In Shielding Of High Atomic Number

    International Nuclear Information System (INIS)

    Yuliati, Helfi; Akhadi, Mukhlis

    2000-01-01

    Research to observe effect of radiation build-up factor (b) in iron (Fe) and lead (Pb) for high energy gamma shielding from exp.137 Cs (E gamma : 662 keV) and exp.60 Co (E gamma : 1332 keV) sources has been carried out. Research was conducted bt counting of radiation intensity behind shielding with its thickness vary from 1 to 5 times of half value thickness (HVT). NaI (TI) detector which connected to multi channel analyzer (MCA) was used for the counting. Calculation result show that all of b value are near to 1 (b∼1) both for Fe and Pb. Without inserting b in calculation, from the experiment it was obtained HVT value of Fe for high gamma radiation of 662 and 1332 keV were : (12,94 n 0,03) mm and (17,33 n 0,01) mm with their deviation standards were 0,2% and 0,06% respectively. Value of HVT for Pb with the same energy were : (6,31 n 0,03) mm and (11,86 n 0,03) mm with their deviation standars were : 0,48% and 0,25% respectively. HVL concept could be applied directly to estimate shielding thickness of high atomic number of high energy gamma radiation, without inserting correction of radiation build-up factor

  7. Importance of the effective atomic number (Zeff) of TL materials for radiation dosimetry in clinical applications

    International Nuclear Information System (INIS)

    Gonzalez M, P.R.

    2008-01-01

    The electric power generation, it has been one of the radiation applications of bigger weight, mainly in developed countries. Another sector of more impact is without a doubt that of the medicine. However, for a sure operation with radiations, those international organisms of radiological safety, exist every time more precise detection systems. The thermoluminescent dosimetry is one of the more reliable methods for this purpose, for that several groups of investigators from different parts of the world, they have guided its investigations in the development of new TL materials. However, to avoid underestimate or overestimation of the measured dose with the use of these materials, it should take into account it effective atomic number (Z eff ) it is well known that some TL materials considered as equivalent to the tissue, presents smaller TL intensity when being irradiated with low energy photons, while the TL material known as not equivalent to the tissue, they present the supra sensitivity effect for this radiation type. Nowadays, the estimate of the Z eff has not been clear, in this work the Z eff is determined by means of the traditional methods and an own method is presented for its determination. The results of the TL signal of different materials, when being irradiated with photons of effective energy between 24 keV and 1.25 MeV and their relationship with their calculated Z eff are also presented. (Author)

  8. Variation of the binary encounter peak energy as a function of projectile atomic number

    International Nuclear Information System (INIS)

    Sanders, J.M.

    1994-01-01

    The energy of the binary encounter peak, in spectra of electrons emitted at 0 degrees with respect to the projectile beam direction, has been studied to investigate its dependence on the atomic number of the projectile ion. The projectiles all had the same squared velocity of 0.6 MeV/u, and all had the same charge q=7. The Z of the projectiles ranged from 8 to 35, and the target was H 2 . The Energy E BEP of the binary encounter peak and also the energy t of the cusp formed by electron loss or electron capture to the projectile continuum (ELC or ECC) were obtained from fits to the spectra. Considerable care was required in fitting the cusp in order to properly ascertain the cusp energy. The energy shift ΔE, defined as the difference between 4t and E BEP , was obtained for each projectile. It is found that the energy shift decreases as the projectile Z increases. This trend is the opposite of that seen for projectile charge where the shift increases as q increases. Such a trend is not well described by the simple elastic scattering model of binary encounter electron production

  9. Charge states of fast heavy ions in solids; target atomic number dependence

    International Nuclear Information System (INIS)

    Shima, Kunihiro

    1985-01-01

    Discussions were carried out on the origin of Z 2 (atomic number) dependent charge states with respect to projectile electron loss and capture process, and on relationship between the Z 2 dependence and that of mean charge states for heavy ions of 1 MeV/u energy region. Present and previously reported results were examined on the equilibrium charge distributions, 9-bar, of 120 MeV 63 Cu, 25 and 40 MeV 35 Cl, 109 MeV Si and 59 MeV F ions. It was clarified that 9-bar became generally higher for lower Z 2 depending on increasing energy, and osillatory behavior with energy-depending amplitude was seen in 9-bar vs Z 2 . Discussions were carrid out on these phenomena and related matters. Z 2 oscillations of 9-bar of fast heavy ions might be due to those of electron capture cross section into projectile K and L vacancies for high and intermediate charge states, respectively. A quantitative interpretation of the Z 2 -dependent 9-bar values is in progress based on collision process and observation of projectile x-ray. The 9-bar value dependency on Z 2 in ion passing foils and decrease of Z 2 oscillation amplitude with increasing collision energy were quite similar to the Z 2 dependence in stopping powers or in effective charge states estimated from stopping powers. But there was some discrepancies in the Z 2 oscillation of 9-bar and that of stopping powers. (Takagi, S.)

  10. Atom

    International Nuclear Information System (INIS)

    Auffray, J.P.

    1997-01-01

    The atom through centuries, has been imagined, described, explored, then accelerated, combined...But what happens truly inside the atom? And what are mechanisms who allow its stability? Physicist and historian of sciences, Jean-Paul Auffray explains that these questions are to the heart of the modern physics and it brings them a new lighting. (N.C.)

  11. An Estimation of the Number and Size of Atoms in a Printed Period

    Science.gov (United States)

    Schaefer, Beth; Collett, Edward; Tabor-Morris, Anne; Croman, Joseph

    2011-01-01

    Elementary school students learn that atoms are very, very small. Students are also taught that atoms (and molecules) are the fundamental constituents of the material world. Numerical values of their size are often given, but, nevertheless, it is difficult to imagine their size relative to one's everyday surroundings. In order for students to…

  12. Direct reconstruction of the effective atomic number of materials by the method of multi-energy radiography

    International Nuclear Information System (INIS)

    Naydenov, Sergey V.; Ryzhikov, Vladimir D.; Smith, Craig F.

    2004-01-01

    A direct method is proposed for reconstruction of the effective atomic number by means of multi-energy radiography of the material. The accuracy of the method is up to 95%. Advantages over conventional radiographic methods, which ensure accuracy of just about 50%, are discussed. A physical model has been constructed and general expressions have been obtained for description of the effective atomic number in a two-energy monitoring scheme. A universal dependence has been predicted for the effective atomic number as a function of relative (two-energy) radiographic reflex. The established theoretical law is confirmed by the experimental data presented. The proposed development can find multiple applications in non-destructive testing and related fields, including those in the civil sphere as well as anti-terrorist activities

  13. Direct reconstruction of the effective atomic number of materials by the method of multi-energy radiography

    Science.gov (United States)

    Naydenov, Sergey V.; Ryzhikov, Vladimir D.; Smith, Craig F.

    2004-02-01

    A direct method is proposed for reconstruction of the effective atomic number by means of multi-energy radiography of the material. The accuracy of the method is up to 95%. Advantages over conventional radiographic methods, which ensure accuracy of just about 50%, are discussed. A physical model has been constructed and general expressions have been obtained for description of the effective atomic number in a two-energy monitoring scheme. A universal dependence has been predicted for the effective atomic number as a function of relative (two-energy) radiographic reflex. The established theoretical law is confirmed by the experimental data presented. The proposed development can find multiple applications in non-destructive testing and related fields, including those in the civil sphere as well as anti-terrorist activities.

  14. The 4-particle hydrogen-anti-hydrogen system revisited. Twofold molecular Hamiltonian symmetry and natural atom anti-hydrogen

    International Nuclear Information System (INIS)

    Van Hooydonk, G.

    2005-01-01

    The historical importance of the original quantum mechanical bond theory proposed by Heitler and London in 1927 as well as its pitfalls are reviewed. Modern ab initio treatments of H-H-bar systems are inconsistent with the logic behind algebraic Hamiltonians H ± = H 0 ± ΔH for charge-symmetrical and charge-asymmetrical 4 unit charge systems like H 2 and HH-bar. Their eigenvalues are exactly those of 1927 Heitler-London (HL) theory. Since these 2 Hamiltonians are mutually exclusive, only the attractive one can apply for stable natural molecular H 2 . A wrong choice leads to problems with anti-atom H-bar. In line with earlier results on band and line spectra, we now prove that HL chose the wrong Hamiltonian for H 2 . Their theory explains the stability of attractive system H 2 with a repulsive Hamiltonian H 0 + ΔH instead of with the attractive one H 0 - ΔH, representative for charge-asymmetrical system HH-bar. A new second order symmetry effect is detected in this attractive Hamiltonian, which leads to a 3-dimensional structure for the 4-particle system. Repulsive HL Hamiltonian H + applies at long range but at the critical distance, attractive charge-inverted Hamiltonian H - takes over and leads to bond H 2 but in reality, HH-bar, for which we give an analytical proof. This analysis confirms and generalizes an earlier critique of the wrong long range behavior of HL-theory by Bingel, Preuss and Schmidtke and by Herring. Another wrong asymptote choice in the past also applies for atomic anti-hydrogen H-bar, which has hidden the Mexican hat potential for natural hydrogen. This generic solution removes most problems, physicists and chemists experience with atomic H-bar and molecular HH-bar, including the problem with antimatter in the Universe. (author)

  15. Perinatal loss and neurological abnormalities among children of the atomic bomb. Nagasaki and Hiroshima revisited, 1949 to 1989

    International Nuclear Information System (INIS)

    Yamazaki, J.N.; Schull, W.J.

    1990-01-01

    Studies of the survivors of the atomic bombing of Hiroshima and Nagasaki who were exposed to ionizing radiation in utero have demonstrated a significant increase in perinatal loss and the vulnerability of the developing fetal brain to injury. These studies have also helped to define the stages in the development of the human brain that are particularly susceptible to radiation-related damage. Exposure at critical junctures in development increases the risk of mental retardation, small head size, subsequent seizures, and poor performance on conventional tests of intelligence and in school. The most critical period, 8 through 15 weeks after fertilization, corresponds to that time in development when neuronal production increases and migration of immature neurons to their cortical sites of function occurs. The epidemiologic data are, however, too sparse to settle unequivocally the nature of the dose-response function and, in particular, whether there is or is not a threshold to damage. If a threshold does exist, it appears to be in the 0.10- to 0.20-Gy fetal-dose range in this vulnerable gestational period

  16. Does the number of nitrogen atoms have an influence on the conducting properties of diphenylazines? A DFT insight

    International Nuclear Information System (INIS)

    Moral, Monica; Granadino-Roldan, Jose Manuel; Garzon, Andres; Garcia, Gregorio; Fernandez-Gomez, Manuel

    2011-01-01

    Research highlights: → Planarity and aromaticity increase when increasing the number of N atoms. → HOMO → LUMO excitation energy decreases when increasing the number of N atoms. → AEA increases stepwise with the number of N atoms up to 1.51 eV for Ph 2 Tz. → Ph 2 Tz becomes the best candidate of the series in terms of electron injection. → Ph 2 T N3 seems to be the best candidate in terms of electron transport. - Abstract: The present study reports on the variation of some structural and electronic properties related to the electron conductivity for the series of diphenylazines represented by the formula Ph-(C 2+n N 4-n H n )-Ph, n = 0 - 4. Properties such as planarity, aromaticity, HOMO → LUMO excitation energy, electron affinity, LUMO level energy, reorganization energy and electron coupling between neighboring molecules in the crystal were analyzed from a theoretical perspective as a function of the number of nitrogen atoms in the molecular structure. As a result, the planarity, aromaticity and electron affinity increase with the number of N atoms in the central ring while the HOMO → LUMO excitation energy and LUMO levels diminish. It is worth noting that up to n = 3, the frontier orbitals appear delocalized throughout the whole system while for n = 4 the localized character of the LUMO might explain the increase in the reorganization energy and thus the higher difficulty to delocalize the excess of negative charge. Electron coupling between neighboring molecules was also estimated on the basis of the energy splitting in dimer method and the reported crystal structures for some of the studied molecules. Accordingly, the highest |t 12 | value was obtained for Ph 2 T N3 (0.06 eV) while Ph 2 Tz should be the most advantageous candidate of the series in terms of electron injection.

  17. Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

    Energy Technology Data Exchange (ETDEWEB)

    Maaloul, L.; Gangwar, R. K.; Stafford, L., E-mail: luc.stafford@umontreal.ca [Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada)

    2015-07-15

    A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from −115 to −300 V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5 ± 1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500 nm revealed a constant excitation temperature of 0.33 ± 0.04 eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12 cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

  18. X-ray fluorescence from the element with atomic number Z=120

    International Nuclear Information System (INIS)

    Fregeau, M.O.; Morjean, M.; Bonnet, E.; Chbihi, A.; Frankland, J.D.; Jacquet, D.; Rivet, M.F.; Tassan-Got, L.; Dechery, F.; Drouart, A.; Nalpas, L.; Ledoux, X.; Parlog, M.; Parlog, M.; Ciortea, C.; Dumitriu, D.; Fluerasu, D.; Gugiu, M.; Gramegna, F.; Kravchuk, V.L.; Marchi, T.; Marchi, T.; Fabris, D.; Corsi, A.; Barlini, S.

    2012-01-01

    An atomic clock based on x-ray fluorescence yields has been used to estimate the mean characteristic time for fusion followed by fission in reactions 238 U + 64 Ni at 6.6 MeV/A. Inner shell vacancies are created during the collisions in the electronic structure of the possibly formed Z = 120 compound nuclei. The filling of these vacancies accompanied by a x-ray emission with energies characteristic of Z = 120 can take place only if the atomic transitions occur before nuclear fission. Therefore, the x-ray yield characteristic of the united atom with 120 protons is strongly related to the fission time and to the vacancy lifetimes. K x rays from the element with Z = 120 have been unambiguously identified from a coupled analysis of the involved nuclear reaction mechanisms and of the measured photon spectra. A minimum mean fission time τ f = 2.5 * 10 -18 s has been deduced for Z = 120 from the measured x-ray multiplicity. (authors)

  19. Effective atomic numbers in some food materials and medicines for γ -ray attenuation using ^{137}Cs γ -ray

    Science.gov (United States)

    Revathy, J. S.; Anooja, J.; Krishnaveni, R. B.; Gangadathan, M. P.; Varier, K. M.

    2018-06-01

    A light-weight multichannel analyser (MCA)-based γ -ray spectrometer, developed earlier at the Inter University Accelerator Centre, New Delhi, has been used as part of the PG curriculum, to determine the effective atomic numbers for γ attenuation of ^{137}Cs γ -ray in different types of samples. The samples used are mixtures of graphite, aluminum and selenium powders in different proportions, commercial and home-made edible powders, fruit and vegetable juices as well as certain allopathic and ayurvedic medications. A narrow beam good geometry set-up has been used in the experiments. The measured attenuation coefficients have been used to extract effective atomic numbers in the samples. The results are consistent with XCOM values wherever available. The present results suggest that the γ attenuation technique can be used as an effective non-destructive method for finding adulteration of food materials.

  20. Effective atomic numbers and effective electron densities for trommel sieve waste and some commonly used building materials

    International Nuclear Information System (INIS)

    Kurudirek, M.; Canimkurbey, B.; Coban, M.; Ayguen, M.; Erzeneoglu, S. Z.

    2010-01-01

    Trommel sieve waste and some commonly used building materials (Portland cement, lime and pointing) have been investigated in terms of effective atomic numbers (Z e ff) and effective electron densities (N e ) by using X- and γ- rays at 22.1, 25 and 88 keV photon energies. A high resolution Si(Li) detector was employed to detect X- and/or γ- radiation coming through in a narrow beam good geometry set-up. Chemical compositions of the materials used in the present study were determined using a wave length dispersive X-ray fluorescence spectrometer (WDXRFS). The variations in photon interaction parameters were discussed regarding the photon energy and chemical composition. The experimental values of effective atomic numbers and effective electron densities were compared with the ones obtained from theory.

  1. Determination of atomic number and composition of human enamel; Determinacao da composicao e numero atomico efetivo do esmalte humano

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, M.S. [Centro Regional de Ciencias Nucleares (CRCN), Recife, PE (Brazil); Rodas Duran, J.E. [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica

    2001-07-01

    The teeth are organs of complicated structure that consist, partly, of hard tissue containing in its interior the dental pulp, rich in vases and nerves. The main mass of the tooth is constituted by the dentine, which is covered with hard tissues and of epithelial origin called enamel. The dentine of the human teeth used in this work were completely removed and the teeth were cut with a device with a diamond disc. In this work the chemical composition of the human enamel was determined, which showed a high percentage of Ca and P, in agreement with the results found in the literature. The effective atomic number of the material and the half-value layer in the energy range of diagnostic X-ray beams were determined. Teeth could be used to evaluated the public's individual doses as well as for retrospective dosimetry what confirms the importance of their effective atomic number and composition determination. (author)

  2. Determination of the Rb atomic number density in dense rubidium vapors by absorption measurements of Rb2 triplet bands

    International Nuclear Information System (INIS)

    Horvatic, Vlasta; Veza, Damir; Niemax, Kay; Vadla, Cedomil

    2008-01-01

    A simple and accurate way of determining atom number densities in dense rubidium vapors is presented. The method relies on the experimental finding that the reduced absorption coefficients of the Rb triplet satellite bands between 740 nm and 750 nm and the triplet diffuse band between 600 nm and 610 nm are not temperature dependent in the range between 600 K and 800 K. Therefore, the absolute values of the reduced absorption coefficients of these molecular bands can provide accurate information about atomic number density of the vapor. The rubidium absorption spectrum was measured by spatially resolved white-light absorption in overheated rubidium vapor generated in a heat pipe oven. The absolute values for the reduced absorption coefficients of the triplet bands were determined at lower vapor densities, by using an accurate expression for the reduced absorption coefficient in the quasistatic wing of the Rb D1 line, and measured triplet satellite bands to the resonance wing optical depth ratio. These triplet satellite band data were used to calibrate in absolute scale the reduced absorption coefficients of the triplet diffuse band at higher temperatures. The obtained values for the reduced absorption coefficient of these Rb molecular features can be used for accurate determination of rubidium atomic number densities in the range from about 5 x 10 16 cm -3 to 1 x 10 18 cm -3

  3. Linguistic influence on mathematical development is specific rather than pervasive: revisiting the Chinese Number Advantage in Chinese and English children

    Directory of Open Access Journals (Sweden)

    Winifred eMark

    2015-02-01

    Full Text Available The relative linguistic transparency of the Asian counting system has been used to explain Asian students’ relative superiority in cross-cultural comparisons of mathematics achievement. To test the validity and extent of linguistic transparency in accounting for mathematical abilities, this study tested Chinese and British primary school children. Children in Hong Kong can learn mathematics using languages with both regular (Chinese and irregular (English counting systems, depending on their schools’ medium of instruction. This makes it possible to compare groups with varying levels of exposure to the regular and irregular number systems within the same educational system, curriculum, and cultural environment. The study included three groups of first/second graders and third/fourth graders with varying degrees of experience to the Chinese language and counting systems: no experience (UK; n=49; spoke Chinese at home and learnt to count in English at school (HK-E; n=43; spoke Chinese at home and learnt to count in Chinese at school (HK-C; n=47. They were compared on counting, numerical abilities and place value representation. The present study also measured nonverbal reasoning, attitude towards mathematics, involvement of parents, and extra-curricular mathematics lessons to explore alternative explanations of children’s numeric ability. Results indicated that students in HK-C were better at counting backward and on the numeric skills test than those in HK-E, who were in turn better than the UK students. However, there was no statistical difference in counting forward, place value understanding, and a measure of arithmetic. Our findings add to existent literature suggesting that linguistic transparency does not have an all-pervasive influence on cross-national differences in arithmetic performance.

  4. Two-Dimensional SnO Anodes with a Tunable Number of Atomic Layers for Sodium Ion Batteries

    KAUST Repository

    Zhang, Fan

    2017-01-18

    We have systematically changed the number of atomic layers stacked in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB) performance. The results indicate that as the number of atomic SnO layers in a sheet decreases, both the capacity and cycling stability of the Na ion battery improve. The thinnest SnO nanosheet anodes (two to six SnO monolayers) exhibited the best performance. Specifically, an initial discharge and charge capacity of 1072 and 848 mAh g-1 were observed, respectively, at 0.1 A g-1. In addition, an impressive reversible capacity of 665 mAh g-1 after 100 cycles at 0.1 A g-1 and 452 mAh g-1 after 1000 cycles at a high current density of 1.0 A g-1 was observed, with excellent rate performance. As the average number of atomic layers in the anode sheets increased, the battery performance degraded significantly. For example, for the anode sheets with 10-20 atomic layers, only a reversible capacity of 389 mAh g-1 could be obtained after 100 cycles at 0.1 A g-1. Density functional theory calculations coupled with experimental results were used to elucidate the sodiation mechanism of the SnO nanosheets. This systematic study of monolayer-dependent physical and electrochemical properties of 2D anodes shows a promising pathway to engineering and mitigating volume changes in 2D anode materials for sodium ion batteries. It also demonstrates that ultrathin SnO nanosheets are promising SIB anode materials with high specific capacity, stable cyclability, and excellent rate performance.

  5. Measuring air core characteristics of a pressure-swirl atomizer via a transparent acrylic nozzle at various Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun J.; Oh, Sang Youp; Kim, Ho Y.; Yoon, Sam S. [Dept. of Mechanical, Korea University Anamdong, 5-Ga, Sungbukgu, 136-713 Seoul (Korea); James, Scott C. [Thermal/Fluid Science and Engineering, Sandia National Labs, PO Box 969, Livermore, CA 94551 (United States)

    2010-11-15

    Because of thermal fluid-property dependence, atomization stability (or flow regime) can change even at fixed operating conditions when subject to temperature change. Particularly at low temperatures, fuel's high viscosity can prevent a pressure-swirl (or simplex) atomizer from sustaining a centrifugal-driven air core within the fuel injector. During disruption of the air core inside an injector, spray characteristics outside the nozzle reflect a highly unstable, nonlinear mode where air core length, Sauter mean diameter (SMD), cone angle, and discharge coefficient variability. To better understand injector performance, these characteristics of the pressure-swirl atomizer were experimentally investigated and data were correlated to Reynolds numbers (Re). Using a transparent acrylic nozzle, the air core length, SMD, cone angle, and discharge coefficient are observed as a function of Re. The critical Reynolds numbers that distinguish the transition from unstable mode to transitional mode and eventually to a stable mode are reported. The working fluids are diesel and a kerosene-based fuel, referred to as bunker-A. (author)

  6. Atom of one electron revisited

    International Nuclear Information System (INIS)

    Yamamoto, J.F.

    1985-01-01

    The steady states of a Dirac's particle under an external electromagnetic potential, described by A μ and its derivatives in presented. Coupling constants are given by the Quantum Electrodynamics. Through a Lagrangian density, a Dirac equation is obtained with terms which present the Lamb shift and the interaction of the anomalous magnetic moment with the nuclear magnetic moment. These effects are treated as perturbations, with the condition Zα [pt

  7. Tomography of atomic number and density of materials using dual-energy imaging and the Alvarez and Macovski attenuation model

    Energy Technology Data Exchange (ETDEWEB)

    Paziresh, M.; Kingston, A. M., E-mail: andrew.kingston@anu.edu.au; Latham, S. J.; Fullagar, W. K.; Myers, G. M. [Department of Applied Mathematics, Research School of physics and Engineering, The Australian National University, Canberra 2601 (Australia)

    2016-06-07

    Dual-energy computed tomography and the Alvarez and Macovski [Phys. Med. Biol. 21, 733 (1976)] transmitted intensity (AMTI) model were used in this study to estimate the maps of density (ρ) and atomic number (Z) of mineralogical samples. In this method, the attenuation coefficients are represented [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)] in the form of the two most important interactions of X-rays with atoms that is, photoelectric absorption (PE) and Compton scattering (CS). This enables material discrimination as PE and CS are, respectively, dependent on the atomic number (Z) and density (ρ) of materials [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)]. Dual-energy imaging is able to identify sample materials even if the materials have similar attenuation coefficients at single-energy spectrum. We use the full model rather than applying one of several applied simplified forms [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976); Siddiqui et al., SPE Annual Technical Conference and Exhibition (Society of Petroleum Engineers, 2004); Derzhi, U.S. patent application 13/527,660 (2012); Heismann et al., J. Appl. Phys. 94, 2073–2079 (2003); Park and Kim, J. Korean Phys. Soc. 59, 2709 (2011); Abudurexiti et al., Radiol. Phys. Technol. 3, 127–135 (2010); and Kaewkhao et al., J. Quant. Spectrosc. Radiat. Transfer 109, 1260–1265 (2008)]. This paper describes the tomographic reconstruction of ρ and Z maps of mineralogical samples using the AMTI model. The full model requires precise knowledge of the X-ray energy spectra and calibration of PE and CS constants and exponents of atomic number and energy that were estimated based on fits to simulations and calibration measurements. The estimated ρ and Z images of the samples used in this paper yield average relative errors of 2.62% and 1.19% and maximum relative errors of 2.64% and 7.85%, respectively. Furthermore, we demonstrate that the method accounts for the beam hardening effect in density (

  8. CrossRef Large numbers of cold positronium atoms created in laser-selected Rydberg states using resonant charge exchange

    CERN Document Server

    McConnell, R; Kolthammer, WS; Richerme, P; Müllers, A; Walz, J; Grzonka, D; Zielinski, M; Fitzakerley, D; George, MC; Hessels, EA; Storry, CH; Weel, M

    2016-01-01

    Lasers are used to control the production of highly excited positronium atoms (Ps*). The laser light excites Cs atoms to Rydberg states that have a large cross section for resonant charge-exchange collisions with cold trapped positrons. For each trial with 30 million trapped positrons, more than 700 000 of the created Ps* have trajectories near the axis of the apparatus, and are detected using Stark ionization. This number of Ps* is 500 times higher than realized in an earlier proof-of-principle demonstration (2004 Phys. Lett. B 597 257). A second charge exchange of these near-axis Ps* with trapped antiprotons could be used to produce cold antihydrogen, and this antihydrogen production is expected to be increased by a similar factor.

  9. Enhancement of phase space density by increasing trap anisotropy in a magneto-optical trap with a large number of atoms

    International Nuclear Information System (INIS)

    Vengalattore, M.; Conroy, R.S.; Prentiss, M.G.

    2004-01-01

    The phase space density of dense, cylindrical clouds of atoms in a 2D magneto-optic trap is investigated. For a large number of trapped atoms (>10 8 ), the density of a spherical cloud is limited by photon reabsorption. However, as the atom cloud is deformed to reduce the radial optical density, the temperature of the atoms decreases due to the suppression of multiple scattering leading to an increase in the phase space density. A density of 2x10 -4 has been achieved in a magneto-optic trap containing 2x10 8 atoms

  10. Surface modes of ultra-cold atomic clouds with very large number of vortices

    Energy Technology Data Exchange (ETDEWEB)

    Cazalilla, M A [Donostia International Physics Center, Donostia (Spain); [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)

    2003-04-01

    We study the surface modes of some of the vortex liquids recently found by means of exact diagonalizations in systems of rapidly rotating bosons. In contrast to the surface modes of Bose condensates, we find that the surface waves have a frequency linear in the excitation angular momentum, h-bar l > 0. Furthermore, in analogy with the edge waves of electronic quantum Hall states, these excitations are chiral, that is, they can be excited only for values of l that increase the total angular momentum of the vortex liquid. However, differently from the quantum Hall phenomena for electrons, we also find other excitations that are approximately degenerate in the laboratory frame with the surface modes, and which decrease the total angular momentum by l quanta. The surface modes of the Laughlin, as well as other scalar and vector boson states are analyzed, and their observable properties characterized. We argue that measurement of the response of a vortex liquid to a weak time-dependent potential that imparts angular momentum to the system should provide valuable information to characterize the vortex liquid. In particular, the intensity of the signal of the surface waves in the dynamic structure factor has been studied and found to depend on the type of vortex liquid. We point out that the existence of surface modes has observable consequences on the density profile of the Laughlin state. These features are due to the strongly correlated behavior of atoms in the vortex liquids. We point out that these correlations should be responsible for a remarkable stability of some vortex liquids with respect to three-body losses. (author)

  11. Atomic Number Dependence of Hadron Production at Large Transverse Momentum in 300 GeV Proton--Nucleus Collisions

    Science.gov (United States)

    Cronin, J. W.; Frisch, H. J.; Shochet, M. J.; Boymond, J. P.; Mermod, R.; Piroue, P. A.; Sumner, R. L.

    1974-07-15

    In an experiment at the Fermi National Accelerator Laboratory we have compared the production of large transverse momentum hadrons from targets of W, Ti, and Be bombarded by 300 GeV protons. The hadron yields were measured at 90 degrees in the proton-nucleon c.m. system with a magnetic spectrometer equipped with 2 Cerenkov counters and a hadron calorimeter. The production cross-sections have a dependence on the atomic number A that grows with P{sub 1}, eventually leveling off proportional to A{sup 1.1}.

  12. Study of mass attenuation coefficients and effective atomic numbers of bismuth-ground granulated blast furnace slag concretes

    International Nuclear Information System (INIS)

    Kumar, Sandeep; Singh, Sukhpal

    2016-01-01

    Five samples of Bismuth-Ground granulated blast furnace slag (Bi-GGBFS) concretes were prepared using composition (0.6 cement + x Bi_2O_3 + (0.4-x) GGBFS, x = 0.05, 0.10, 0.15, 0.20 and 0.25) by keeping constant water (W) cement (C) ratio. Mass attenuation coefficients (μ_m) of these prepared samples were calculated using a computer program winXCOM at different gamma ray energies, whereas effective atomic numbers (Z_e_f_f) is calculated using mathematical formulas. The radiation shielding properties of Bi-GGBFS concrete has been compared with standard radiation shielding concretes.

  13. Effects of non-LTE multiplet dynamics on lumped-state modelling in moderate to high atomic number plasmas

    International Nuclear Information System (INIS)

    Whitney, K G; Dasgupta, A; Davis, J; Coverdale, C A

    2007-01-01

    Two atomic models of the population dynamics of substates within the n 4 and n = 3 multiplets of nickel-like tungsten and beryllium-like iron, respectively, are described in this paper. The flexible atomic code (FAC) is used to calculate the collisional and radiative couplings and energy levels of the excited states within these ionization stages. These atomic models are then placed within larger principal-quantum-number-based ionization dynamic models of both tungsten and iron plasmas. Collisional-radiative equilibrium calculations are then carried out using these models that demonstrate how the multiplet substates depart from local thermodynamic equilibrium (LTE) as a function of ion density. The effect of these deviations from LTE on the radiative and collisional deexcitation rates of lumped 3s, 3p, 3d, 4s, 4p, 4d and 4f states is then calculated and least-squares fits to the density dependence of these lumped-state rate coefficients are obtained. The calculations show that, with the use of lumped-state models (which are in common use), one can accurately model the L- and M-shell ionization dynamics occurring in present-day Z-pinch experiments only through the addition of these extra, non-LTE-induced, rate coefficient density dependences. However, the derivation and use of low-order polynomial fits to these density dependences makes lumped-state modelling both viable and of value for post-processing analyses

  14. Lakatos Revisited.

    Science.gov (United States)

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social…

  15. Influence of density and mean atomic number on CT attenuation corrected PET: Phantom studies

    International Nuclear Information System (INIS)

    Maintas, D.; Houzard, C.; Galy, G.; Maintas, C.; Itti, R.; Cachin, F.; Mognetti, Th.; Slosman

    2007-01-01

    Aim: the aim of this work is to study the influence of medium density on the CT or external source attenuation corrected images, by simulation on a phantom, with various positron emission tomographs. Material and method: a series of experiments on a cylindrical phantom filled with water marked with [18 F]-FDG, containing six vials filled per pair with mediums of different densities or solutions of KI, CaCl 2 and saccharose with various densities, was carried out under comparable conditions on three different tomographs. In only one of the vials of each pair, an identical radioactivity of [18 F]-FDG was added, three to five fold the surrounding activity. The reconstructions and attenuation corrections suggested by the manufacturers, were carried out under the usual conditions of each site. The activity of each structure was estimated by the methods of profiles and regions of interest, on the non attenuation corrected images (N.A.C.), the images corrected by CT (C.T.A.C.), and/or external source (G.P.A.C.). Results: with all three tomographs, the activities estimated on the N.A.C. images present an inverse correlation to the medium density (important absorption by dense material). On C.T.A.C. images, we observed with only two of the three tomographs, an overestimation of the activity in the 'radioactive' vials, depending on the medium mean Z number and density (over correction), and a artifactual 'activity' in the denser 'cold' vial (incorrect attenuation correction. The dense saccharose solutions, with non elevated Z number, do not affect the CT attenuation correction. (authors)

  16. Does the number of nitrogen atoms have an influence on the conducting properties of diphenylazines? A DFT insight

    Science.gov (United States)

    Moral, Mónica; Granadino-Roldán, José Manuel; Garzón, Andrés; García, Gregorio; Fernández-Gómez, Manuel

    2011-01-01

    The present study reports on the variation of some structural and electronic properties related to the electron conductivity for the series of diphenylazines represented by the formula Ph sbnd (C 2+nN 4-nH n) sbnd Ph, n = 0 - 4. Properties such as planarity, aromaticity, HOMO → LUMO excitation energy, electron affinity, LUMO level energy, reorganization energy and electron coupling between neighboring molecules in the crystal were analyzed from a theoretical perspective as a function of the number of nitrogen atoms in the molecular structure. As a result, the planarity, aromaticity and electron affinity increase with the number of N atoms in the central ring while the HOMO → LUMO excitation energy and LUMO levels diminish. It is worth noting that up to n = 3, the frontier orbitals appear delocalized throughout the whole system while for n = 4 the localized character of the LUMO might explain the increase in the reorganization energy and thus the higher difficulty to delocalize the excess of negative charge. Electron coupling between neighboring molecules was also estimated on the basis of the energy splitting in dimer method and the reported crystal structures for some of the studied molecules. Accordingly, the highest | t12| value was obtained for Ph 2T N3 (0.06 eV) while Ph 2Tz should be the most advantageous candidate of the series in terms of electron injection.

  17. High fidelity simulation and analysis of liquid jet atomization in a gaseous crossflow at intermediate Weber numbers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoyi, E-mail: lixy2@utrc.utc.com; Soteriou, Marios C. [United Technologies Research Center, East Hartford, Connecticut 06108 (United States)

    2016-08-15

    Recent advances in numerical methods coupled with the substantial enhancements in computing power and the advent of high performance computing have presented first principle, high fidelity simulation as a viable tool in the prediction and analysis of spray atomization processes. The credibility and potential impact of such simulations, however, has been hampered by the relative absence of detailed validation against experimental evidence. The numerical stability and accuracy challenges arising from the need to simulate the high liquid-gas density ratio across the sharp interfaces encountered in these flows are key reasons for this. In this work we challenge this status quo by presenting a numerical model able to deal with these challenges, employing it in simulations of liquid jet in crossflow atomization and performing extensive validation of its results against a carefully executed experiment with detailed measurements in the atomization region. We then proceed to the detailed analysis of the flow physics. The computational model employs the coupled level set and volume of fluid approach to directly capture the spatiotemporal evolution of the liquid-gas interface and the sharp-interface ghost fluid method to stably handle high liquid-air density ratio. Adaptive mesh refinement and Lagrangian droplet models are shown to be viable options for computational cost reduction. Moreover, high performance computing is leveraged to manage the computational cost. The experiment selected for validation eliminates the impact of inlet liquid and gas turbulence and focuses on the impact of the crossflow aerodynamic forces on the atomization physics. Validation is demonstrated by comparing column surface wavelengths, deformation, breakup locations, column trajectories and droplet sizes, velocities, and mass rates for a range of intermediate Weber numbers. Analysis of the physics is performed in terms of the instability and breakup characteristics and the features of downstream

  18. On the atomic-number similarity of the binding energies of electrons in filled shells of elements of the periodic table

    Science.gov (United States)

    Karpov, V. Ya.; Shpatakovskaya, G. V.

    2017-03-01

    An expression for the binding energies of electrons in the ground state of an atom is derived on the basis of the Bohr-Sommerfeld quantization rule within the Thomas-Fermi model. The validity of this relation for all elements from neon to uranium is tested within a more perfect quantum-mechanical model with and without the inclusion of relativistic effects, as well as with experimental binding energies. As a result, the ordering of electronic levels in filled atomic shells is established, manifested in an approximate atomic-number similarity. It is proposed to use this scaling property to analytically estimate the binding energies of electrons in an arbitrary atom.

  19. On the atomic-number similarity of the binding energies of electrons in filled shells of elements of the periodic table

    Energy Technology Data Exchange (ETDEWEB)

    Karpov, V. Ya. [Bruk Institute of Electronic Control Machines (Russian Federation); Shpatakovskaya, G. V., E-mail: shpagalya@yandex.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation)

    2017-03-15

    An expression for the binding energies of electrons in the ground state of an atom is derived on the basis of the Bohr–Sommerfeld quantization rule within the Thomas–Fermi model. The validity of this relation for all elements from neon to uranium is tested within a more perfect quantum-mechanical model with and without the inclusion of relativistic effects, as well as with experimental binding energies. As a result, the ordering of electronic levels in filled atomic shells is established, manifested in an approximate atomic-number similarity. It is proposed to use this scaling property to analytically estimate the binding energies of electrons in an arbitrary atom.

  20. A non-destructive technique for assigning effective atomic number to scientific samples by scattering of 59.54 keV gamma photons

    International Nuclear Information System (INIS)

    Singh, M.P.; Sharma, Amandeep; Singh, Bhajan; Sandhu, B.S.

    2010-01-01

    The objective of present experiment, employing a scattering of 59.54 keV gamma photons, is to assign effective atomic number (Z eff ) to scientific samples (rare earths) of known composition. An HPGe semiconductor detector, placed at 90 o to the incident beam, detects gamma photons scattered from the sample under investigation. The experiment is performed on various elements with atomic number satisfying, 6≤Z≤82, for 59.54 keV incident photons. The intensity ratio of Rayleigh to Compton scattered peaks, corrected for photo-peak efficiency of gamma detector and absorption of photons in the sample and air, is plotted as a function of atomic number and constituted a best fit-curve. From this fit-curve, the respective effective atomic numbers to samples of rare earths are determined. The agreement of measured values of Z eff with theoretical calculations is quite satisfactory.

  1. Study of the relationship between peaks scattering Rayleigh to Compton ratio and effective atomic number in biological samples

    International Nuclear Information System (INIS)

    Pereira, Marcelo O.; Conti, Claudio de Carvalho; Anjos, Marcelino J.; Lopes, Ricardo T.

    2011-01-01

    The aim of this work was to develop a new method to correct the absorbed radiation (the mass attenuation coefficient curve) in low energy (E B O 3 , Na 2 CO 3 , CaCO 3 , Al 2 O 3 , K 2 SO 4 and MgO) of radiation produced by a gamma-ray source of Am-241(59.54 keV) also applied to certified biological samples of milk powder, hay powder and bovine liver (NIST 155 7B). In addition, six methods of effective atomic number determination were used as described in literature to determinate the Rayleigh to Compton scattering ratio (R/C) , in order to calculate the mass attenuation coefficient. The results obtained by the proposed method were compared with those obtained using the transmission method. The experimental results were in good agreement with transmission values suggesting that the method to correct radiation absorption presented in this paper is adequate for biological samples. (author)

  2. Determination of Atomic Number Exponent for Elemental Absorber at Am-241 Energy in X-Ray Attenuation Experiments

    International Nuclear Information System (INIS)

    Najim, L.A.; Shamoon, S.K.; Atalah, S.T.

    2012-01-01

    In X-ray absorption experiment, the dependence of the photoelectric absorption cross-section varied with atomic number Z.In this paper, the dependence on Z of the cross-section or coefficient of photoelectric absorption is first evaluated from published data for (20) elements ranging from Al-Sn, and then the cross-section for Fe is obtained experimentally by measuring the X-ray intensity with and without the Fe absorber and compared with the theoretical value, the variation of the photoelectric absorption coefficient (μ/ρ m ) showed less dependence on Z for the two tested of Z regions.This is because of the inclusion of mass density (ρ m ) of the absorber in the coefficient.The values of m obtained in the present work increases linearly with energy for both ranges of elements

  3. Improvement of analysis precision upon the atomic number and electron density measurement by the dual x-ray CT

    Science.gov (United States)

    Imura, Yukino; Morii, Hisashi; Koike, Akifumi; Okunoyama, Takaharu; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

    2010-08-01

    To identify the factor impairing the material identification parameters, which is provided by the dual-energy X-ray computed tomography method using a conventional X-ray tube and a CdTe detector, linear attenuation coefficient was measured by the radioactivity of radio isotopes and compared with theoretical figure. In our study, the atomic number and the electron density is calculated from the linear attenuation coefficient obtained in CT measurement by 64-channel CdTe line detector. To estimate accuracy of CdTe line sensor, it is needed to obtain the linear attenuation coefficient accurately. Using a single detector, the linear attenuation coefficient is verified for accuracy. The energy resolution of CdTe detectors and the method of reconstruction are discussed.

  4. Measurement of mass attenuation coefficients of moderate-to-high atomic-number elements at low photon energies

    International Nuclear Information System (INIS)

    Tajuddin, A.A.; Chong, C.S.; Shukri, A.; Bradley, D.A.

    1995-01-01

    Mass attenuation coefficients for 12 selected moderate-to-high atomic-number elements have been obtained from good-geometry measurements made at five 241 Am photon energies of significant emission intensity. Particular interest focuses on measured values for photon energies close to absorption edges. Comparisons with renormalized cross-section predictions indicate agreement to within stated error limits for the majority of cases. Significant discrepancies (> 10%) are noted for Ta at 17.8 and 26.3 keV and W at 59.5 keV. Some support for a discrepancy between measurement and theory for W in the region of 60 keV is found in the reported measurements of others. (author)

  5. Mass attenuation coefficients, effective atomic and electron numbers of stainless steel and carbon steels with different energies

    International Nuclear Information System (INIS)

    Mohd Fakarudin Abdul Rahman; Mohd Iqbal Saripan; Nor Paiza Mohamad Hasan; Ismail Mustapha

    2011-01-01

    The total mass attenuation coefficients (μ/ ρ) of stainless steel (SS316L) and carbon steel (A516) that are widely used as petrochemical plant components, such as distillation column, heat exchanger, boiler and storage tank were measured at 662, 1073 and 1332 keV of photon energies. Measurements of radiation intensity for various thicknesses of steel were made by using transmission method. The γ-ray intensity were counted by using a Gamma spectrometer that contains a Hyper-pure Germanium (HPGe) detector connected with Multi Channel Analyzer (MCA). The effective numbers of atomic (Z eff ) and electron (N eff ) obtained experimentally were compared by those obtained through theoretical calculation. Both experimental and calculated values of Z eff and N eff were in good agreement. (author)

  6. A study of energy and effective atomic number dependence of the exposure build-up factors in biological samples

    International Nuclear Information System (INIS)

    Sidhu, G.S.; Singh, P.S.; Mudahar, G.S.

    2000-01-01

    A theoretical method is presented to determine the gamma-radiation build-up factors in various biological materials. The gamma energy range is 0.015-15.0 MeV, with penetration depths up to 40 mean free paths considered. The dependence of the exposure build-up factor on incident photon energy and the effective atomic number (Z eff ) has also been assessed. In a practical analysis of dose burden to gamma-irradiated biological materials, the sophistication of Monte Carlo computer techniques would be applied, with associated detailed modelling. However, a feature of the theoretical method presented is its ability to make the consequences of the physics of the scattering process in biological materials more transparent. In addition, it can be quickly employed to give a first-pass dose estimate prior to a more detailed computer study. (author)

  7. Sensemaking Revisited

    DEFF Research Database (Denmark)

    Holt, Robin; Cornelissen, Joep

    2014-01-01

    We critique and extend theory on organizational sensemaking around three themes. First, we investigate sense arising non-productively and so beyond any instrumental relationship with things; second, we consider how sense is experienced through mood as well as our cognitive skills of manipulation ...... research by revisiting Weick’s seminal reading of Norman Maclean’s book surrounding the tragic events of a 1949 forest fire at Mann Gulch, USA....

  8. Stability investigation of a high number density Pt1/Fe2O3 single-atom catalyst under different gas environments by HAADF-STEM

    Science.gov (United States)

    Duan, Sibin; Wang, Rongming; Liu, Jingyue

    2018-05-01

    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 Pt1/Fe2O3 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, Fe2O3 supported Pt single atoms are stable even at high temperatures. The presence of either CO or H2 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 H2 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 H2O molecules to the CO or H2 significantly accelerates the sintering of the Fe2O3 supported Pt single atoms. An anchoring-site determined sintering mechanism is further proposed, which is related to the metal–support interaction.

  9. Experimental research on the contrast production of the chemical elements with the atomic numbers 1-83 in a computer-totalbody-tomogram

    International Nuclear Information System (INIS)

    Kirschner, H.; Burmester, U.; Stringaris, K.

    1979-01-01

    The contrast production for the chemical elements with the atomic numbers Z=1-83 were determined by computer-tomography. With the formula relation of the Δ-number and the atomic number can one compute the contrast production of any chosen chemical compound. Iodine-free and inorganic iodine-containing contrast media are examined for their contrast production and compared with presently used organic iodine-containing contrast media. The contrast enhancement of organic contrast media in tissue are discussed. (orig.) [de

  10. Bottomonium spectrum revisited

    CERN Document Server

    Segovia, Jorge; Entem, David R.; Fernández, Francisco

    2016-01-01

    We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about the better way to determine their properties experimentally.

  11. On the effective atomic number and electron density: A comprehensive set of formulas for all types of materials and energies above 1 keV

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K.S.

    2008-01-01

    A comprehensive and consistent set of formulas is given for calculating the effective atomic number and electron density for all types of materials and for all photon energies greater than 1 keV. The are derived from first principles using photon interaction cross sections of the constituent atom....... The theory is illustrated by calculations and experiments for molecules of medical and biological interest, glasses for radiation shielding, alloys, minerals and liquids....

  12. Effective atomic numbers and electron densities of some biologically important compounds containing H, C, N and O in the energy range 145-1330 keV

    International Nuclear Information System (INIS)

    Manjunathaguru, V; Umesh, T K

    2006-01-01

    A semi-empirical relation which can be used to determine the total attenuation cross sections of samples containing H, C, N and O in the energy range 145-1332 keV has been derived based on the total attenuation cross sections of several sugars, amino acids and fatty acids. The cross sections have been measured by performing transmission experiments in a narrow beam good geometry set-up by employing a high-resolution hyperpure germanium detector at seven energies of biological importance such as 145.4 keV, 279.2 keV, 514 keV, 661.6 keV, 1115.5 keV, 1173.2 keV and 1332.1 keV. The semi-empirical relation can reproduce the experimental values within 1-2%. The total attenuation cross sections of five elements carbon, aluminium, titanium, copper and zirconium measured in the same experimental set-up at the energies mentioned above have been used in a new matrix method to evaluate the effective atomic numbers and the effective electron densities of samples such as cholesterol, fatty acids, sugars and amino acids containing H, C, N and O atoms from their effective atomic cross sections. The effective atomic cross sections are the total attenuation cross sections divided by the total number of atoms of all types in a particular sample. Further, a quantity called the effective atomic weight was defined as the ratio of the molecular weight of a sample to the total number of atoms of all types in it. The variation of the effective atomic number was systematically studied with respect to the effective atomic weight and a new semi-empirical relation for Z eff has been evolved. It is felt that this relation can be very useful to determine the effective atomic number of any sample having H, C, N and O atoms in the energy range 145-1332 keV irrespective of its chemical structure

  13. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    International Nuclear Information System (INIS)

    Sanford, T.W.L.; Mosher, D.; De Groot, J.S.

    1996-01-01

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single-exploded-wire discharges on Gamble-II suggest a common nonthermal-production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission. (author). 3 figs., 10 refs

  14. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    International Nuclear Information System (INIS)

    Sanford, T.W.L.; Mosher, D.; De Groot, J.S.

    1996-01-01

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single- exploded-wire discharges on Gamble-II suggest a common nonthermal- production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly- collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission

  15. A study of effective atomic numbers and electron densities of some vitamins for electron, H, He and C ion interactions

    Science.gov (United States)

    Büyükyıldız, M.

    2017-09-01

    The radiological properties of some vitamins such as Retinol, Beta-carotene, Riboflavin, Niacin, Niacinamide, Pantothenic acid, Pyridoxine, Pyridoxamine, Pyridoxal, Biotin, Folic acid, Ascorbic acid, Cholecalciferol, Alpha-tocopherol, Gamma-tocopherol, Phylloquinone have been investigated with respect to total electron interaction and some heavy charged particle interaction as means of effective atomic numbers (Z_{eff}) and electron densities (N_{eff}) for the first time. Calculations were performed for total electron interaction and heavy ions such as H, He and C ion interactions in the energy region 10keV-10MeV by using a logarithmic interpolation method. Variations in Z_{eff}'s and N_{eff}'s of given vitamins have been studied according to the energy of electron or heavy charged particles, and significant variations have been observed for all types of interaction in the given energy region. The maximum values of Z_{eff} have been found in the different energy regions for different interactions remarkably and variations in N_{eff} seem approximately to be the same with variation in Z_{eff} for the given vitamins as expected. Z_{eff} values of some vitamins were plotted together and compared with each other for electron, H, He and C interactions and the ratios of Z_{eff}/ have been changed in the range of 0.25-0.36, 0.20-0.36, 0.22-0.35 and 0.20-0.35 for electron, H, He and C interactions, respectively.

  16. Stabilisation of ZrO/sub 2/ with rare-earth oxides with atomic numbers from 58 to 71

    Energy Technology Data Exchange (ETDEWEB)

    Tcheivili, L; Passarino de Marques, M N [Instituto Nacional de Tecnologia Industrial, Buenos Aires (Argentina)

    1978-01-01

    In the present work, the stabilisation of ZrO/sub 2/ with 14 rare earths (58 to 71) was investigated. The aim was to carry out the experiments at a temperature of 1550/sup 0/C, at which many oxides do not exist in the cubic form and the others, such as PrO/sub 2/ and Lu/sub 2/O/sub 3/, have not yet been studied. All the experiments of the series were carried out under constant conditions, in order to determine if there was any difference in principle between them. All the oxides stabilise ZrO/sub 2/, but those with the lower atomic numbers (58, 59, 60) show some deviation. The minimum and maximum mol% limits were ascertained, between which ZrO/sub 2/ is fully stabilised, and the phases are given which occur with the various mol% proportions. In conclusion, an experiment was carried out with all oxides having di- tri- and quadri-valent cations, which belong to the cubic system. In view of their difference in ionic radius to the Zr/sup 4 +/ ion, the conclusion can be drawn that all oxides which can stabilise ZrO/sub 2/ have larger cation radii than that of the Zr/sup 4 +/ ion.

  17. Effective atomic numbers, electron densities, and tissue equivalence of some gases and mixtures for dosimetry of radiation detectors

    Directory of Open Access Journals (Sweden)

    Singh Vishwanath P.

    2012-01-01

    Full Text Available Total mass attenuation coefficients, µm, effective atomic number, Zeff, and effective electron density, Neff, of different gases - carbon dioxide, methane, acetylene, propane, butane, and pentane used in radiation detectors, have been calculated for the photon energy of 1 keV to 100 GeV. Each gas has constant Zeff values between 0.10 to 10 MeV photon energies; however, these values are way far away from ICRU tissue. Carbon dioxide gas shows the closest tissue equivalence in the entire photon energy spectrum. Relative tissue equivalences of the mixtures of gases with respect to ICRU tissue are in the range of 0.998-1.041 for air, argon (4.5% + methane (95.5%, argon (0.5% + carbon dioxide (99.5%, and nitrogen (5% + methane (7% + carbon dioxide (88%. The gas composition of xenon (0.5% + carbon dioxide (99.5% shows 1.605 times higher tissue equivalence compared to the ICRU tissue. The investigated photon interaction parameters are useful for exposure and energy absorption buildup factors calculation and design, and fabrication of gaseous detectors for ambient radiation measurement by the Geiger-Muller detector, ionization chambers and proportional counters.

  18. Mechanism of cluster DNA damage repair in response to high-atomic number and energy particles radiation

    Energy Technology Data Exchange (ETDEWEB)

    Asaithamby, Aroumougame, E-mail: Aroumougame.Asaithamy@UTsouthwestern.edu [Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390 (United States); Chen, David J., E-mail: David.Chen@UTsouthwestern.edu [Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390 (United States)

    2011-06-03

    Low-linear energy transfer (LET) radiation (i.e., {gamma}- and X-rays) induces DNA double-strand breaks (DSBs) that are rapidly repaired (rejoined). In contrast, DNA damage induced by the dense ionizing track of high-atomic number and energy (HZE) particles is slowly repaired or is irreparable. These unrepaired and/or misrepaired DNA lesions may contribute to the observed higher relative biological effectiveness for cell killing, chromosomal aberrations, mutagenesis, and carcinogenesis in HZE particle irradiated cells compared to those treated with low-LET radiation. The types of DNA lesions induced by HZE particles have been characterized in vitro and usually consist of two or more closely spaced strand breaks, abasic sites, or oxidized bases on opposing strands. It is unclear why these lesions are difficult to repair. In this review, we highlight the potential of a new technology allowing direct visualization of different types of DNA lesions in human cells and document the emerging significance of live-cell imaging for elucidation of the spatio-temporal characterization of complex DNA damage. We focus on the recent insights into the molecular pathways that participate in the repair of HZE particle-induced DSBs. We also discuss recent advances in our understanding of how different end-processing nucleases aid in repair of DSBs with complicated ends generated by HZE particles. Understanding the mechanism underlying the repair of DNA damage induced by HZE particles will have important implications for estimating the risks to human health associated with HZE particle exposure.

  19. Mechanism of cluster DNA damage repair in response to high-atomic number and energy particles radiation

    International Nuclear Information System (INIS)

    Asaithamby, Aroumougame; Chen, David J.

    2011-01-01

    Low-linear energy transfer (LET) radiation (i.e., γ- and X-rays) induces DNA double-strand breaks (DSBs) that are rapidly repaired (rejoined). In contrast, DNA damage induced by the dense ionizing track of high-atomic number and energy (HZE) particles is slowly repaired or is irreparable. These unrepaired and/or misrepaired DNA lesions may contribute to the observed higher relative biological effectiveness for cell killing, chromosomal aberrations, mutagenesis, and carcinogenesis in HZE particle irradiated cells compared to those treated with low-LET radiation. The types of DNA lesions induced by HZE particles have been characterized in vitro and usually consist of two or more closely spaced strand breaks, abasic sites, or oxidized bases on opposing strands. It is unclear why these lesions are difficult to repair. In this review, we highlight the potential of a new technology allowing direct visualization of different types of DNA lesions in human cells and document the emerging significance of live-cell imaging for elucidation of the spatio-temporal characterization of complex DNA damage. We focus on the recent insights into the molecular pathways that participate in the repair of HZE particle-induced DSBs. We also discuss recent advances in our understanding of how different end-processing nucleases aid in repair of DSBs with complicated ends generated by HZE particles. Understanding the mechanism underlying the repair of DNA damage induced by HZE particles will have important implications for estimating the risks to human health associated with HZE particle exposure.

  20. Spectral effects on some physical coefficients of x-Ray interaction with materials of low atomic number

    International Nuclear Information System (INIS)

    EL-Kazzaz, S.A.; Youssef, M.; EL-Hadad, S.; and EL-Nadi, L.M.

    1988-01-01

    X-ray spectra were measured before and after passing through some materials of medical importance applying X-ray diffraction. The mass absorption coefficients of these materials were determined at X-ray peak voltages 27, 30 and 42 kV-p making use the measured spectrum and also by using the direct beam absorption. It has been found that the mass absorption coefficients calculated from the X-ray spectral distribution analysis are in general lower than those obtained considering the direct beam method. From the study of the atomic number and energy dependence of the mass absorption coefficients it has been found that the dependence of the coefficients calculated from the spectral distribution is good agreement with the previously studied data for monoenergetic x-ray beam. Also the roentgen - to - Rad conversion factors were determined at the different used energies and materials. The value of the mass absorption coefficients calculated from the spectral distribution is recommended for use in dose calculation

  1. Experimental observations of electron-backscatter effects from high-atomic-number anodes in large-aspect-ratio, electron-beam diodes

    Energy Technology Data Exchange (ETDEWEB)

    Cooperstein, G; Mosher, D; Stephanakis, S J; Weber, B V; Young, F C [Naval Research Laboratory, Washington, DC (United States); Swanekamp, S B [JAYCOR, Vienna, VA (United States)

    1997-12-31

    Backscattered electrons from anodes with high-atomic-number substrates cause early-time anode-plasma formation from the surface layer leading to faster, more intense electron beam pinching, and lower diode impedance. A simple derivation of Child-Langmuir current from a thin hollow cathode shows the same dependence on the diode aspect ratio as critical current. Using this fact, it is shown that the diode voltage and current follow relativistic Child-Langmuir theory until the anode plasma is formed, and then follows critical current after the beam pinches. With thin hollow cathodes, electron beam pinching can be suppressed at low voltages (< 800 kV) even for high currents and high-atomic-number anodes. Electron beam pinching can also be suppressed at high voltages for low-atomic-number anodes as long as the electron current densities remain below the plasma turn-on threshold. (author). 8 figs., 2 refs.

  2. Cell-killing efficiency and number of platinum atoms binding to DNA, RNA and protein molecules of HeLa cells treated with combinations of hyperthermia and carboplatin

    International Nuclear Information System (INIS)

    Akaboshi, M.; Kawai, K.; Tanaka, Y.; Takada, J.; Sumino, T.

    1999-01-01

    The effect of hyperthermia on the cell killing efficiency of Pt atoms binding to DNA, RNA and protein molecules of HeLa cells treated with cis-diamine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA) was examined. HeLa S-3 cells were treated with 195m Pt-radiolabeled CBDCA for 60 minutes at various temperatures, and the relationship between the lethal effect and the number of Pt atoms binding to DNA, RNA and proteins was examined. The mean lethal concentration (D 0 ) of carboplatin for a 60 min-treatment at 0, 25, 37, 40, 42 and 44 deg C was 671.2, 201.5, 67.3, 33.4, 20.2 and 15.6 μM, respectively. By using identically treated cells, the number of Pt-atoms combined with DNA, RNA and protein molecules were determined in the subcellular fractions. Thus, the D 0 's given as the drug concentrations were replaced with the number of Pt-atoms combined in each fraction. Then, the cell-killing efficiency of the Pt atom was expressed as the reciprocal of the number of Pt-atoms combined and was calculated for each molecule. The efficiency for DNA molecules was 0.699, 1.42, 2.65, 4.84, 7.74 and 8.28x10 4 nucleotides, respectively, for the conditions described above. From 0 to 44 deg C, the cell-killing efficiency of Pt atoms increased by a factor of 11.9. (author)

  3. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    International Nuclear Information System (INIS)

    Sanford, T.W.L.; Nash, T.J.; Marder, B.M.

    1996-03-01

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays, driven by 5 MA from the Saturn accelerator, are measured and compared with LLNL Radiation-Hydro-Code (RHC) and SNL Hydro-Code (HC) numerical models. Multiple implosions, due to sequential compressions and expansions of the plasma, are inferred from the measured multiple x-radiation bursts. Timing of the multiple implosions and the thermal x-ray spectra measured between 1 and 10 keV are consistent with the RHC simulations. The magnitude of the nonthermal x-ray emission measured from 10 to 100 keV ranges from 0.02 to 0.08% of the total energy radiated and is correlated with bright-spot emission along the z-axis, as observed in earlier Gamble-11 single exploding-wire experiments. The similarities of the measured nonthermal spectrum and bright-spot emission with those measured at 0.8 MA on Gamble-II suggest a common production mechanism for this process. A model of electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas is developed, which shows the existence of a critical electric field, E c , below which strong nonthermal electron creation (and the associated nonthermal x rays) do not occur. HC simulations show that significant nonthermal electrons are not expected in this experiment (as observed) because the calculated electric fields are at least one to two orders-of-magnitude below E c . These negative nonthermal results are confirmed by RHC simulations using a nonthermal model based on a Fokker-Plank analysis. Lastly, the lower production efficiency and the larger, more irregular pinch spots formed in this experiment relative to those measured on Gamble II suggest that implosion geometries are not as efficient as single exploding-wire geometries for warm x-ray production

  4. Development of a standard data base for FBR core nuclear design. 10. Reevaluation of atomic number density of JOYO Mk-II core

    Energy Technology Data Exchange (ETDEWEB)

    Numata, Kazuyuki; Sato, Wakaei [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center; Ishikawa, Makoto; Arii, Yoshio [Nuclear Energy System Incorporation, Tokyo (Japan)

    1999-07-01

    The material composition of JOYO Mk-II core components in its initial core was reevaluated as a part of the effort for developing a standard data base for FBR core nuclear design. The special feature of the reevaluation is to treat the decay of Pu-241 isotope, so that the atomic number densities of Pu-241 and Am-241 in fuel assemblies can be exactly evaluated on the initial critical date, Nov. 22nd, 1982. Further, the atomic number densities of other core components were also evaluated to improve the analytical accuracy. Those include the control rods which were not so strictly evaluated in the past, and the dummy fuels and the neutron sources which were not treated in the analytical model so far. The results of the present reevaluation were as follows: (1) The changes of atomic number densities of the major nuclides such as Pu-239, U-235 and U-238 were about {+-}0.2 to 0.3%. On the other hand, the number density of Pu-241, which was the motivation of the present work, was reduced by 12%. From the fact, the number densities in the past analysis might be based on the isotope measurement of the manufacturing point of time without considering the decay of Pu-241. (2) As the other core components, the number densities of control rods and outer reflector-type A were largely improved. (author)

  5. SU-C-BRC-05: Monte Carlo Calculations to Establish a Simple Relation of Backscatter Dose Enhancement Around High-Z Dental Alloy to Its Atomic Number

    Energy Technology Data Exchange (ETDEWEB)

    Utsunomiya, S; Kushima, N; Katsura, K; Tanabe, S; Hayakawa, T; Sakai, H; Yamada, T; Takahashi, H; Abe, E; Wada, S; Aoyama, H [Niigata University, Niigata (Japan)

    2016-06-15

    Purpose: To establish a simple relation of backscatter dose enhancement around a high-Z dental alloy in head and neck radiation therapy to its average atomic number based on Monte Carlo calculations. Methods: The PHITS Monte Carlo code was used to calculate dose enhancement, which is quantified by the backscatter dose factor (BSDF). The accuracy of the beam modeling with PHITS was verified by comparing with basic measured data namely PDDs and dose profiles. In the simulation, a high-Z alloy of 1 cm cube was embedded into a tough water phantom irradiated by a 6-MV (nominal) X-ray beam of 10 cm × 10 cm field size of Novalis TX (Brainlab). The ten different materials of high-Z alloys (Al, Ti, Cu, Ag, Au-Pd-Ag, I, Ba, W, Au, Pb) were considered. The accuracy of calculated BSDF was verified by comparing with measured data by Gafchromic EBT3 films placed at from 0 to 10 mm away from a high-Z alloy (Au-Pd-Ag). We derived an approximate equation to determine the relation of BSDF and range of backscatter to average atomic number of high-Z alloy. Results: The calculated BSDF showed excellent agreement with measured one by Gafchromic EBT3 films at from 0 to 10 mm away from the high-Z alloy. We found the simple linear relation of BSDF and range of backscatter to average atomic number of dental alloys. The latter relation was proven by the fact that energy spectrum of backscatter electrons strongly depend on average atomic number. Conclusion: We found a simple relation of backscatter dose enhancement around high-Z alloys to its average atomic number based on Monte Carlo calculations. This work provides a simple and useful method to estimate backscatter dose enhancement from dental alloys and corresponding optimal thickness of dental spacer to prevent mucositis effectively.

  6. Effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV

    International Nuclear Information System (INIS)

    Prasannakumar, S.; Umesh, T.K.

    2014-01-01

    The effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV by using Compton scattering cross sections which are determined on a goniometer assembly. An ORTEC model 23210 gamma-x high purity germanium detector (HpGe) has been used to record the data along with a personal computer based MCA in the angular region 50°-110°. The effective atomic numbers so obtained were found to be equal to the total number of electrons present in the sample in accordance with the chemical formula. The results so obtained are of first of their kind at these energies and are expected to be important in a variety of applications of radiation physics and chemistry. (author)

  7. Analytical dependence of effective atomic number on the elemental composition of matter and radiation energy in the range 10-1000 keV

    Science.gov (United States)

    Eritenko, A. N.; Tsvetiansky, A. L.; Polev, A. A.

    2018-01-01

    In the present paper, a universal analytical dependence of effective atomic number on the composition of matter and radiation energy is proposed. This enables one to consider the case of a strong difference in the elemental composition with respect to their atomic numbers over a wide energy range. The contribution of photoelectric absorption and incoherent and coherent scattering during the interaction between radiation and matter is considered. For energy values over 40 keV, the contribution of coherent scattering does not exceed approximately 10% that can be neglected at a further consideration. The effective atomic numbers calculated on the basis of the proposed relationships are compared to the results of calculations based on other methods considered by different authors on the basis of experimental and tabulated data on mass and atomic attenuation coefficients. The examination is carried out for both single-element (e.g., 6C, 14Si, 28Cu, 56Ba, and 82Pb) and multi-element materials. Calculations are performed for W1-xCux alloys (x = 0.35; x = 0.4), PbO, ther moluminescent dosimetry compounds (56Ba, 48Cd, 41Sr, 20Ca, 12Mg, and 11Na), and SO4 in a wide energy range. A case with radiation energy between the K- and L1-absorption edges is considered for 82Pb, 74W, 56Ba, 48Cd, and 38Sr. This enables to substantially simplify the calculation of the atomic number and will be useful in technical and scientific fields related to the interaction between X-ray/gamma radiation and matter.

  8. Revisit of the Saito-Dresselhaus-Dresselhaus C2 ingestion model: on the mechanism of atomic-carbon-participated fullerene growth.

    Science.gov (United States)

    Wang, Wei-Wei; Dang, Jing-Shuang; Zhao, Xiang; Nagase, Shigeru

    2017-11-09

    We introduce a mechanistic study based on a controversial fullerene bottom-up growth model proposed by R. Saito, G. Dresselhaus, and M. S. Dresselhaus. The so-called SDD C 2 addition model has been dismissed as chemically inadmissible but here we prove that it is feasible via successive atomic-carbon-participated addition and migration reactions. Kinetic calculations on the formation of isolated pentagon rule (IPR)-obeying C 70 and Y 3 N@C 80 are carried out by employing the SDD model for the first time. A stepwise mechanism is proposed with a considerably low barrier of ca. 2 eV which is about 3 eV lower than a conventional isomerization-containing fullerene growth pathway.

  9. Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV

    International Nuclear Information System (INIS)

    Manohara, S.R.; Hanagodimath, S.M.

    2007-01-01

    Effective atomic numbers for photon energy-absorption (Z PEAeff ) of essential amino acids histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been calculated by a direct method in the energy region of 1 keV to 20 MeV. The Z PEAeff values have been found to change with energy and composition of the amino acids. The variations of mass energy-absorption coefficient, effective atomic number for photon interaction (Z PIeff ) and Z PEAeff with energy are shown graphically. Significant differences exist between Z PIeff and the Z PEAeff in the energy region of 8-100 keV for histidine and threonine; 6-100 keV for leucine, lysine, tryptophan, phenylalanine and valine; 15-400 keV for methionine. The effect of absorption edge on effective atomic numbers and the possibility of defining two set values of these parameters at the K-absorption edge of high-Z element present in the amino acids are discussed. The reasons for using Z PEAeff rather than the commonly used Z PIeff in medical radiation dosimetry for the calculation of absorbed dose in radiation therapy are also discussed

  10. Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30-1333 keV

    International Nuclear Information System (INIS)

    Gowda, Shivalinge; Krishnaveni, S.; Gowda, Ramakrishna

    2005-01-01

    The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30-1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data

  11. Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30-1333 keV

    Energy Technology Data Exchange (ETDEWEB)

    Gowda, Shivalinge [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India); Krishnaveni, S. [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India); Gowda, Ramakrishna [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India)]. E-mail: ramakrishnagowda@yahoo.com

    2005-10-15

    The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30-1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

  12. A different perspective to the effective atomic number (Zeff) for some boron compounds and trommel sieve waste (TSW) with a new computer program ZXCOM

    International Nuclear Information System (INIS)

    Yalçın, Zeynel; İçelli, Orhan; Okutan, Mustafa; Boncukçuoğlu, Recep; Artun, Ozan; Orak, Salim

    2012-01-01

    In this study, the effective atomic number (Z eff )has been calculated for some boron compounds, such as concentrate colemanite, tincal, ulexite, boric acid, probertite and TSW (Trommel Sieve Waste) by means of ZXCOM at incident beam energy (E 0 =59.543 keV) and scattering angle (θ=35°). We present and discuss the (Z eff ) obtained by Rayleigh/Compton (R/C) ratio and evaluated for the purpose of radiation shielding which contains boron compounds, which are commonly used as shield materials. -- Highlights: ► The (Z eff ) of an infinite number of compounds will be determined according to the number actually consisting of elements which correspond to an integer number at the curve of ZXCOM. ► The result of this study shows that the effective atomic number (Z eff ) is closely related to the scattering angles. ► The main objective of the study is to construct a computer program, ZXCOM, to calculate the (Z eff ) at compromise (E 0 ) and (θ) for each element, compound and mixture.

  13. A correlation between isomer shifts of 237Np Moessbauer spectra and coordination numbers of Np atoms in neptunyl(V) compounds

    International Nuclear Information System (INIS)

    Saeki, M.; Nakada, M.; Nakamoto, T.; Yamashita, T.; Masaki, N.M.; Krot, N.N.

    1999-01-01

    Five neptunyl(V) compounds were synthesized and studied by 237 Np Moessbauer spectroscopy. The isomer shifts (δ) of the Moessbauer spectra ranged from -18.6 to -19.1 mm/s for the compounds with Np atoms surrounded by 7 oxygen atoms (coordination number (CN) 7). On the other hand, the larger value of δ was obtained for the compound with CN 8. From the comparison of the present results with those reported on neptunyl(V) and (VI) compounds, it is concluded that there is a correlation between the δ and the CN for neptunyl(V) compounds, and the distribution of δ is narrower for neptunyl(V) compounds than that of neptunyl(VI) compounds. (author)

  14. Influence of the number of atomic levels on the spectral opacity of low temperature nickel and iron in the spectral range 50-300 eV

    International Nuclear Information System (INIS)

    Busquet, M.; Klapisch, M.; Gilles, D.

    2013-01-01

    Opacity is a fundamental ingredient for the secular evolution of stars. The calculation of the stellar plasma absorption coefficients is complex due to the composition of these plasmas, generally an H /He dominated mixture with a low concentration of partially ionized heavy ions (the iron group). The international collaboration OPAC recently presented extensive comparisons of spectral opacities of iron and nickel for temperatures between 15 and 40 eV and for densities of ∼ 3 mg/cm 3 , relevant to the stellar envelope conditions [1, 2]. The role of Configuration Interaction (CI) and the influence of the number of atomic levels on the opacity using the recently improved version of HULLAC atomic code [3, 4] are illustrated in this article. Comparisons with theoretical predictions already presented in [1] are discussed. (authors)

  15. Correlation between catalytic activity and bonding and coordination number of atoms and molecules on transition metal surfaces: theory and experimental evidence

    International Nuclear Information System (INIS)

    Falicov, L.M.; Somorjai, G.A.

    1985-01-01

    Correlation between catalytic activity and low-energy local electronic fluctuation in transition metals is proposed. A theory and calculations are presented which indicate that maximum electronic fluctuants take place at high-coordination metal sites. Either (i) atomically rough surfaces that expose to the reactant molecules atoms with large numbers of nonmagnetic or weakly magnetic neighbors in the first or second layer at the surface or (ii) stepped and kinked surfaces are the most active in carrying out structure-sensitive catalytic reactions. The synthesis of ammonia from N 2 and H 2 over iron and rhenium surfaces, 1 H 2 / 2 H 2 exchange over stepped platinum crystal surfaces at low pressures, and the hydrogenolysis (C - C bond breaking) of isobutane at kinked platinum crystal surfaces are presented as experimental evidence in support of the theory

  16. 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

  17. 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.

  18. Quantification of differences in the effective atomic numbers of healthy and cancerous tissues: A discussion in the context of diagnostics and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, M. L. [School of Applied Sciences and Health Innovation Research Institute, RMIT University, Melbourne 3000 (Australia); Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne 3001 (Australia) and Medical Physics, WBRC, Alfred Hospital, Melbourne 3000 (Australia)

    2012-09-15

    Purpose: There are a range of genetic and nongenetic factors influencing the elemental composition of different human tissues. The elemental composition of cancerous tissues frequently differs from healthy tissue of the same organ, particularly in high-Z trace element concentrations. For this reason, one could suggest that this may be exploited in diagnostics and perhaps even influence dosimetry. Methods: In this work, for the first time, effective atomic numbers are computed for common cancerous and healthy tissues using a robust, energy-dependent approach between 10 keV and 100 MeV. These are then quantitatively compared within the context of diagnostics and dosimetry. Results: Differences between effective atomic numbers of healthy and diseased tissues are found to be typically less than 10%. Fibrotic tissues and calcifications of the breast exhibit substantial (tens to hundreds of percent) differences to healthy tissue. Expectedly, differences are most pronounced in the photoelectric regime and consequently most relevant for kV imaging/therapy and radionuclides with prominent low-energy peaks. Cancerous tissue of the testes and stomach have lower effective atomic numbers than corresponding healthy tissues, while diseased tissues of the other organ sites typically have higher values. Conclusions: As dose calculation approaches improve in accuracy, there may be an argument for the explicit inclusion of pathologies. This is more the case for breast, penile, prostate, nasopharyngeal, and stomach cancer, less so for testicular and kidney cancer. The calculated data suggest dual-energy computed tomography could potentially improve lesion identification in the aforementioned organs (with the exception of testicular cancer), with most import in breast imaging. Ultimately, however, the differences are very small. It is likely that the assumption of a generic 'tissue ramp' in planning will be sufficient for the foreseeable future, and that the Z differences do

  19. Quantification of differences in the effective atomic numbers of healthy and cancerous tissues: A discussion in the context of diagnostics and dosimetry

    International Nuclear Information System (INIS)

    Taylor, M. L.

    2012-01-01

    Purpose: There are a range of genetic and nongenetic factors influencing the elemental composition of different human tissues. The elemental composition of cancerous tissues frequently differs from healthy tissue of the same organ, particularly in high-Z trace element concentrations. For this reason, one could suggest that this may be exploited in diagnostics and perhaps even influence dosimetry. Methods: In this work, for the first time, effective atomic numbers are computed for common cancerous and healthy tissues using a robust, energy-dependent approach between 10 keV and 100 MeV. These are then quantitatively compared within the context of diagnostics and dosimetry. Results: Differences between effective atomic numbers of healthy and diseased tissues are found to be typically less than 10%. Fibrotic tissues and calcifications of the breast exhibit substantial (tens to hundreds of percent) differences to healthy tissue. Expectedly, differences are most pronounced in the photoelectric regime and consequently most relevant for kV imaging/therapy and radionuclides with prominent low-energy peaks. Cancerous tissue of the testes and stomach have lower effective atomic numbers than corresponding healthy tissues, while diseased tissues of the other organ sites typically have higher values. Conclusions: As dose calculation approaches improve in accuracy, there may be an argument for the explicit inclusion of pathologies. This is more the case for breast, penile, prostate, nasopharyngeal, and stomach cancer, less so for testicular and kidney cancer. The calculated data suggest dual-energy computed tomography could potentially improve lesion identification in the aforementioned organs (with the exception of testicular cancer), with most import in breast imaging. Ultimately, however, the differences are very small. It is likely that the assumption of a generic “tissue ramp” in planning will be sufficient for the foreseeable future, and that the Z differences do not

  20. Dualism revisited.

    Science.gov (United States)

    Searle, John R

    2007-01-01

    The problem of consciousness should eventually receive a scientific solution, but there are a number of scientific and philosophical obstacles along the way. I offer solutions to the philosophical problems and proposals for approaching the scientific problems.

  1. Cold Incineration of Chlorophenols in Aqueous Solution by Advanced Electrochemical Process Electro-Fenton. Effect of Number and Position of Chlorine Atoms on the Degradation Kinetics

    Science.gov (United States)

    Oturan, Nihal; Panizza, Marco; Oturan, Mehmet A.

    2009-09-01

    This study reports the kinetics of the degradation of several chlorophenols (CPs), such as monochlorophenols (2-chlorophenol and 4-chlorophenol), dichlorophenols (2,4-dichlorophenol and 2,6- dichlorophenol), trichlorophenols (2,3,5- trichlorophenol and 2,4,5-trichlorophenol), 2,3,5,6-tetrachlorophenol, and pentachlorophenol, by the electro-Fenton process using a carbon felt cathode and a Pt anode. The effect of number and the position of the chlorine atoms in the aromatic ring on the oxidative degradation rate was evaluated and discussed. The oxidation reaction of all the CPs with hydroxyl radicals evidenced a pseudo-first-order kinetics and the rate constant decreased with increasing the number of chlorine atoms. The absolute rate constant of second-order reaction kinetics between CPs and •OH was determined by the competition kinetics method in the range of (3.56-7.75) × 109 M-1 s-1 and follows the same sequence of the apparent rate constants. The mineralization of several CPs and of a mixture of all CPs under study was monitored by the total organic carbon (TOC) removal and the chlorine release during mineralization was followed by ion chromatography. Our results demonstrated that more chlorinated phenols are more difficult to mineralize; however for all the tested CPs, almost quantitative release of chloride ions was obtained after 6 h of treatment.

  2. A study of the effective atomic number of SixPb0.7-x(Fe2O30.3 ternary alloys for photons

    Directory of Open Access Journals (Sweden)

    Buyukyildiz Mehmet

    2016-01-01

    Full Text Available The effective atomic number (Zeff of SixPb0.7-x(Fe2O30.3 ternary alloys was obtained for photons. Rayleigh to Compton scattering ratio (R/C has been determined to obtain the Zeff of SixPb0.7-x(Fe2O30.3 ternary alloys of varying Si and Pb (10 %-60 % content for scattering of 59.54 keV g-rays at an angle of 130°. The theoretical R/C ratios of elements were plotted as a function of the atomic number and fitted to a polynomial equation. Experimental R/C values of alloys were then used to obtain Zeff using this fit equation. Also, Zeff values of these alloys were determined for the first time by interpolating the R/C of the material using the R/C data of adjacent elements in between the R/C of the alloy lies. The agreement between the interpolation method and the fit equation was quite satisfactory. The obtained Zeff for photon scattering were then compared to the Zeff for total photon attenuation obtained using the Auto-Zeff program. Significant variations were observed between the Zeff for scattering and the total attenuation of gamma rays.

  3. A comparative study on total reflection X-ray fluorescence determination of low atomic number elements in air, helium and vacuum atmospheres using different excitation sources

    Science.gov (United States)

    Misra, N. L.; Kanrar, Buddhadev; Aggarwal, S. K.; Wobrauschek, Peter; Rauwolf, M.; Streli, Christina

    2014-09-01

    A comparison of trace element determinations of low atomic number (Z) elements Na, Mg, Al, P, K and Ca in air, helium and vacuum atmospheres using W Lβ1, Mo Kα and Cr Kα excitations has been made. For Mo Kα and W Lβ1 excitations a Si (Li) detector with beryllium window was used and measurements were performed in air and helium atmospheres. For Cr Kα excitation, a Si (Li) detector with an ultra thin polymer window (UTW) was used and measurements were made in vacuum and air atmospheres. The sensitivities of the elemental X-ray lines were determined using TXRF spectra of standard solutions and processing them by IAEA QXAS program. The elemental concentrations of the elements in other solutions were determined using their TXRF spectra and pre-determined sensitivity values. The study suggests that, using the above experimental set up, Mo Kα excitation is not suited for trace determination of low atomic number element. Excitation by WLβ1 and helium atmosphere, the spectrometer can be used for the determination of elements with Z = 15 (P) and above with fairly good detection limits whereas Cr Kα excitation with ultra thin polymer window and vacuum atmosphere is good for the elements having Z = 11 (Na) and above. The detection limits using this set up vary from 7048 pg for Na to 83 pg for Ti.

  4. 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.)

  5. Oxidative phosphorylation revisited

    DEFF Research Database (Denmark)

    Nath, Sunil; Villadsen, John

    2015-01-01

    The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic...

  6. Superconductivity revisited

    CERN Document Server

    Dougherty, Ralph

    2013-01-01

    While the macroscopic phenomenon of superconductivity is well known and in practical use worldwide in many industries, including MRIs in medical diagnostics, the current theoretical paradigm for superconductivity (BCS theory) suffers from a number of limitations, not the least of which is an adequate explanation of high temperature superconductivity. This book reviews the current theory and its limitations and suggests new ideas and approaches in addressing these issues. The central objective of the book is to develop a new, coherent, understandable theory of superconductivity directly based on molecular quantum mechanics.

  7. Studies on effective atomic numbers for photon energy absorption and electron density of some narcotic drugs in the energy range 1 keV-20 MeV

    Science.gov (United States)

    Gounhalli, Shivraj G.; Shantappa, Anil; Hanagodimath, S. M.

    2013-04-01

    Effective atomic numbers for photon energy absorption ZPEA,eff, photon interaction ZPI,eff and for electron density Nel, have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for narcotic drugs, such as Heroin (H), Cocaine (CO), Caffeine (CA), Tetrahydrocannabinol (THC), Cannabinol (CBD), Tetrahydrocannabivarin (THCV). The ZPEA,eff, ZPI,eff and Nel values have been found to change with energy and composition of the narcotic drugs. The energy dependence ZPEA,eff, ZPI,eff and Nel is shown graphically. The maximum difference between the values of ZPEA,eff, and ZPI,eff occurs at 30 keV and the significant difference of 2 to 33% for the energy region 5-100 keV for all drugs. The reason for these differences is discussed.

  8. Effective atomic numbers and electron densities of bacteriorhodopsin and its comprising amino acids in the energy range 1 keV–100 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, Morteza; Lunscher, Nolan [Waterloo Institute for Nanotechnology and Department of Systems Design Engineering, University of Waterloo, 200 University Ave., W., Waterloo, Ontario, Canada N2L 3G1 (Canada); Yeow, John T.W., E-mail: jyeow@uwaterloo.ca [Waterloo Institute for Nanotechnology and Department of Systems Design Engineering, University of Waterloo, 200 University Ave., W., Waterloo, Ontario, Canada N2L 3G1 (Canada)

    2013-04-01

    Recently, there has been an interest in fabrication of X-ray sensors based on bacteriorhodopsin, a proton pump protein in cell membrane of Halobacterium salinarium. Therefore, a better understanding of interaction of X-ray photons with bacteriorhodopsin is required. We use WinXCom program to calculate the mass attenuation coefficient of bacteriorhodopsin and its comprising amino acids for photon energies from 1 keV to 100 GeV. These amino acids include alanine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, Asx1, Asx2, Glx1 and Glx2. We then use that data to calculate effective atomic number and electron densities for the same range of energy. We also emphasize on two ranges of energies (10–200 keV and 1–20 MeV) in which X-ray imaging and radiotherapy machines work.

  9. Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

    Directory of Open Access Journals (Sweden)

    Guanglong Chen

    2015-10-01

    Full Text Available The supersonic gas jets from conical nozzles are simulated using 2D model. The on-axis atom number density in gas jet is investigated in detail by comparing the simulated densities with the idealized densities of straight streamline model in scaling laws. It is found that the density is generally lower than the idealized one and the deviation between them is mainly dependent on the opening angle of conical nozzle, the nozzle length and the gas backing pressure. The density deviation is then used to discuss the deviation of the equivalent diameter of a conical nozzle from the idealized deq in scaling laws. The investigation on the lateral expansion of gas jet indicates the lateral expansion could be responsible for the behavior of the density deviation. These results could be useful for the estimation of cluster size and the understanding of experimental results in laser-cluster interaction experiments.

  10. Mass attenuation coefficient (μ/ρ), effective atomic number (Zeff) and measurement of x-ray energy spectra using based calcium phosphate biomaterials: a comparative study

    International Nuclear Information System (INIS)

    Fernandes Z, M. A.; Da Silva, T. A.; Nogueira, M. S.; Goncalves Z, E.

    2015-10-01

    In dentistry, alveolar bone regeneration procedures using based calcium phosphate biomaterials have been shown effective. However,there are not reports in the literature of studies the interaction of low energy radiation in these biomaterials used as attenuator and not being then allowed a comparison between the theoretical values and experimental.The objective of this study was to determine the interaction of radiation parameters of four dental biomaterials - BioOss, Cerasorb M Dental, Straumann Boneceramic and Osteogen for diagnostic radiology qualities. As a material and methods, the composition of the biomaterials was determined by the analytical techniques. The samples with 0.181 cm to 0,297 cm thickness were experimentally used as attenuators for the measurement of the transmitted X-rays spectra in X-ray equipment with 50 to 90 kV range by spectrometric system comprising the Cd Te detector. After this procedure, the mass attenuation coefficient, the effective atomic number were determined and compared between all the specimens analyzed, using the program WinXCOM in the range of 10 to 200 keV. In all strains examined observed that the energy spectrum of x-rays transmitted through the BioOss has the mean energy slightly smaller than the others biomaterials for close thickness. The μ/ρ and Z eff of the biomaterials showed its dependence on photon energy and atomic number of the elements of the material analyzed. It is concluded according to the methodology employed in this study that the measurements of x-ray spectrum, μ/ρ and Z eff using biomaterials as attenuators confirmed that the thickness, density, composition of the samples, the incident photon energy are factors that determine the characteristics of radiation in a tissue or equivalent material. (Author)

  11. A simple formulation for deriving effective atomic numbers via electron density calibration from dual-energy CT data in the human body.

    Science.gov (United States)

    Saito, Masatoshi; Sagara, Shota

    2017-06-01

    The main objective of this study is to propose a simple formulation (which we called DEEDZ) for deriving effective atomic numbers (Z eff ) via electron density (ρ e ) calibration from dual-energy (DE) CT data. We carried out numerical analysis of this DEEDZ method for a large variety of materials with known elemental compositions and mass densities using an available photon cross sections database. The new conversion approach was also applied to previously published experimental DECT data to validate its practical feasibility. We performed numerical analysis of the DEEDZ conversion method for tissue surrogates that have the same chemical compositions and mass densities as a commercial tissue-characterization phantom in order to determine the parameters necessary for the ρ e and Z eff calibrations in the DEEDZ conversion. These parameters were then applied to the human-body-equivalent tissues of ICRU Report 46 as objects of interest with unknown ρ e and Z eff . The attenuation coefficients of these materials were calculated using the XCOM photon cross sections database. We also applied the DEEDZ conversion to experimental DECT data available in the literature, which was measured for two commercial phantoms of different shapes and sizes using a dual-source CT scanner at 80 kV and 140 kV/Sn. The simulated Z eff 's were in excellent agreement with the reference values for almost all of the ICRU-46 human tissues over the Z eff range from 5.83 (gallstones-cholesterol) to 16.11 (bone mineral-hydroxyapatite). The relative deviations from the reference Z eff were within ± 0.3% for all materials, except for one outlier that presented a -3.1% deviation, namely, the thyroid. The reason for this discrepancy is that the thyroid contains a small amount of iodine, an element with a large atomic number (Z = 53). In the experimental case, we confirmed that the simple formulation with less fit parameters enable to calibrate Z eff as accurately as the existing calibration

  12. Charge fraction of 6.0 MeV/n heavy ions with a carbon foil: Dependence on the foil thickness and projectile atomic number

    CERN Document Server

    Sato, Y; Muramatsu, M; Murakami, T; Yamada, S; Kobayashi, C; Kageyama, Y; Miyoshi, T; Ogawa, H; Nakabushi, H; Fujimoto, T; Miyata, T; Sano, Y

    2003-01-01

    We measured the charge fraction of 6.0 MeV/n heavy ions (C, Ne, Si, Ar, Fe and Cu) with a carbon foil at the NIRS-HIMAC injector. At this energy they are stripped with a carbon foil before being injected into two synchrotron rings with a maximum energy of 800 MeV/n. In order to find the foil thickness (D sub E) at which an equilibrium charge state distribution occurs, and to study the dependence of the D sub E -values on the projectile atomic number, we measured the exit charge fractions for foil thicknesses of between 10 and 350 mu g/cm sup 2. The results showed that the D sub E -values are 21.5, 62.0, 162, 346, 121, 143 mu g/cm sup 2 for C, Ne, Si, Ar, Fe, Cu, respectively. The fraction of Ar sup 1 sup 8 sup + ions was actually improved to 33% at 320 mu g/cm sup 2 from approx 15% at 100 mu g/cm sup 2. For Fe and Cu ions, the D sub E -values were found to be only 121 and 143 mu g/cm sup 2; there is a large gap between Ar and Fe, which is related to the differences in the ratio of the binding energy of the K-...

  13. A method to determine exactly the effective atomic number, electron density and absorbtion coefficient of materials from two Computer-Tomography measurement

    International Nuclear Information System (INIS)

    Christ, G.

    1981-01-01

    By the method of computer tomography, which is in use since about 10 years, X-ray images of a layer of interest can be produced without interference from the material present above this layer. An integral measurement of the attenuation of continuous X-radiation is sufficient to record the different attenuation behaviour in a layer for the purpose of image formation. For more information, however, can be obtained by taking into account the spectral distribution of the X-ray source and the energy dependence of the attenuation, which varies for different materials. In the experimental part of this work the measurement of the spectral distribution is described together with the necessary corrections, and the possible application of the cross sections for the relevant interaction processes, which are known from the literature is studied. As shown in the theoretical part, the attenuation coefficient can be described by an effective atomic number and the electron density of the absorber in the case of an arbitrary mixture of absorbing materials and a continuous X-ray spectrum. These two unknown material parameters can be determined by a method based on the measurement of two spectra with different spectral distribution. This is demonstrated by a one-dimensional and a two-dimensional computer simulation. (orig./WU) [de

  14. Determination of effective atomic number of breast tissues using scattered radiation; Determinacao do numero atomico efetivo de tecidos mamarios usando a radiacao espalhada

    Energy Technology Data Exchange (ETDEWEB)

    Antoniassi, M.; Conceicao, A.L.C.; Poletti, M.E. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Fac. de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica

    2010-07-01

    The scattered radiation has been used in several industrial and clinical applications since it permits to characterize the scattering material. Several types of information can be extracted from the spectrum of scattered radiation which can be used to characterization of biological tissues such as breast tissues. In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose), benign (fibroadenoma) and malignant (carcinoma) neoplastic breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90 deg C (x = 0.99 angstrom-1). A practical method using the area of elastic and inelastic scattering was used for determining the effective atomic number (Z{sub eff}) of the samples, being validated comparing the experimental obtained values of Z{sub eff} of several standard materials with calculated values using traditional method based on total cross-section of compounds. The obtained results show that exist differences in the distributions of Z{sub eff} of breast tissues, which are related to the content of carbon (Z=6) and oxygen (Z=8) in each tissue type. The results suggest that is possible to use this parameter for characterizing breast tissues, pointing the possibility of its use as a complementary tool for the diagnosis of the breast cancer. (author)

  15. Chemical composition, effective atomic number and electron density study of trommel sieve waste (TSW), Portland cement, lime, pointing and their admixtures with TSW in different proportions

    International Nuclear Information System (INIS)

    Kurudirek, Murat; Aygun, Murat; Erzeneoglu, Salih Zeki

    2010-01-01

    The trommel sieve waste (TSW) which forms during the boron ore production is considered to be a promising building material with its use as an admixture with Portland cement and is considered to be an alternative radiation shielding material, also. Thus, having knowledge on the chemical composition and radiation interaction properties of TSW as compared to other building materials is of importance. In the present study, chemical compositions of the materials used have been determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Also, TSW, some commonly used building materials (Portland cement, lime and pointing) and their admixtures with TSW have been investigated in terms of total mass attenuation coefficients (μ/ρ), photon interaction cross sections (σ t ), effective atomic numbers (Z eff ) and effective electron densities (N e ) by using X-rays at 22.1, 25 keV and γ-rays at 88 keV photon energies. Possible conclusions were drawn with respect to the variations in photon energy and chemical composition.

  16. Revisiting Okun's Relationship

    NARCIS (Netherlands)

    Dixon, R.; Lim, G.C.; van Ours, Jan

    2016-01-01

    Our paper revisits Okun's relationship between observed unemployment rates and output gaps. We include in the relationship the effect of labour market institutions as well as age and gender effects. Our empirical analysis is based on 20 OECD countries over the period 1985-2013. We find that the

  17. Revisiting the Okun relationship

    NARCIS (Netherlands)

    Dixon, R. (Robert); Lim, G.C.; J.C. van Ours (Jan)

    2017-01-01

    textabstractOur article revisits the Okun relationship between observed unemployment rates and output gaps. We include in the relationship the effect of labour market institutions as well as age and gender effects. Our empirical analysis is based on 20 OECD countries over the period 1985–2013. We

  18. Bounded Intention Planning Revisited

    OpenAIRE

    Sievers Silvan; Wehrle Martin; Helmert Malte

    2014-01-01

    Bounded intention planning provides a pruning technique for optimal planning that has been proposed several years ago. In addition partial order reduction techniques based on stubborn sets have recently been investigated for this purpose. In this paper we revisit bounded intention planning in the view of stubborn sets.

  19. A Hydrostatic Paradox Revisited

    Science.gov (United States)

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  20. The Faraday effect revisited

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, Gheorghe

    2009-01-01

    This paper is the second in a series revisiting the (effect of) Faraday rotation. We formulate and prove the thermodynamic limit for the transverse electric conductivity of Bloch electrons, as well as for the Verdet constant. The main mathematical tool is a regularized magnetic and geometric...

  1. Calculation of effective atomic number and electron density of essential biomolecules for electron, proton, alpha particle and multi-energetic photon interactions

    Science.gov (United States)

    Kurudirek, Murat; Onaran, Tayfur

    2015-07-01

    Effective atomic numbers (Zeff) and electron densities (Ne) of some essential biomolecules have been calculated for total electron interaction, total proton interaction and total alpha particle interaction using an interpolation method in the energy region 10 keV-1 GeV. Also, the spectrum weighted Zeff for multi-energetic photons has been calculated using Auto-Zeff program. Biomolecules consist of fatty acids, amino acids, carbohydrates and basic nucleotides of DNA and RNA. Variations of Zeff and Ne with kinetic energy of ionizing charged particles and effective photon energies of heterogeneous sources have been studied for the given materials. Significant variations in Zeff and Ne have been observed through the entire energy region for electron, proton and alpha particle interactions. Non-uniform variation has been observed for protons and alpha particles in low and intermediate energy regions, respectively. The maximum values of Zeff have found to be in higher energies for total electron interaction whereas maximum values have found to be in relatively low energies for total proton and total alpha particle interactions. When it comes to the multi-energetic photon sources, it has to be noted that the highest Zeff values were found at low energy region where photoelectric absorption is the pre-dominant interaction process. The lowest values of Zeff have been shown in biomolecules such as stearic acid, leucine, mannitol and thymine, which have highest H content in their groups. Variation in Ne seems to be more or less the same with the variation in Zeff for the given materials as expected.

  2. Generalized Pauli constraints in small atoms

    Science.gov (United States)

    Schilling, Christian; Altunbulak, Murat; Knecht, Stefan; Lopes, Alexandre; Whitfield, James D.; Christandl, Matthias; Gross, David; Reiher, Markus

    2018-05-01

    The natural occupation numbers of fermionic systems are subject to nontrivial constraints, which include and extend the original Pauli principle. A recent mathematical breakthrough has clarified their mathematical structure and has opened up the possibility of a systematic analysis. Early investigations have found evidence that these constraints are exactly saturated in several physically relevant systems, e.g., in a certain electronic state of the beryllium atom. It has been suggested that, in such cases, the constraints, rather than the details of the Hamiltonian, dictate the system's qualitative behavior. Here, we revisit this question with state-of-the-art numerical methods for small atoms. We find that the constraints are, in fact, not exactly saturated, but that they lie much closer to the surface defined by the constraints than the geometry of the problem would suggest. While the results seem incompatible with the statement that the generalized Pauli constraints drive the behavior of these systems, they suggest that the qualitatively correct wave-function expansions can in some systems already be obtained on the basis of a limited number of Slater determinants, which is in line with numerical evidence from quantum chemistry.

  3. Leukemia and ionizing radiation revisited

    Energy Technology Data Exchange (ETDEWEB)

    Cuttler, J.M. [Cuttler & Associates Inc., Vaughan, Ontario (Canada); Welsh, J.S. [Loyola University-Chicago, Dept. or Radiation Oncology, Stritch School of Medicine, Maywood, Illinois (United States)

    2016-03-15

    A world-wide radiation health scare was created in the late 19508 to stop the testing of atomic bombs and block the development of nuclear energy. In spite of the large amount of evidence that contradicts the cancer predictions, this fear continues. It impairs the use of low radiation doses in medical diagnostic imaging and radiation therapy. This brief article revisits the second of two key studies, which revolutionized radiation protection, and identifies a serious error that was missed. This error in analyzing the leukemia incidence among the 195,000 survivors, in the combined exposed populations of Hiroshima and Nagasaki, invalidates use of the LNT model for assessing the risk of cancer from ionizing radiation. The threshold acute dose for radiation-induced leukemia, based on about 96,800 humans, is identified to be about 50 rem, or 0.5 Sv. It is reasonable to expect that the thresholds for other cancer types are higher than this level. No predictions or hints of excess cancer risk (or any other health risk) should be made for an acute exposure below this value until there is scientific evidence to support the LNT hypothesis. (author)

  4. 'Felson Signs' revisited

    International Nuclear Information System (INIS)

    George, Phiji P.; Irodi, Aparna; Keshava, Shyamkumar N.; Lamont, Anthony C.

    2014-01-01

    In this article we revisit, with the help of images, those classic signs in chest radiography described by Dr Benjamin Felson himself, or other illustrious radiologists of his time, cited and discussed in 'Chest Roentgenology'. We briefly describe the causes of the signs, their utility and the differential diagnosis to be considered when each sign is seen. Wherever possible, we use CT images to illustrate the basis of some of these classic radiographic signs.

  5. Time functions revisited

    Science.gov (United States)

    Fathi, Albert

    2015-07-01

    In this paper we revisit our joint work with Antonio Siconolfi on time functions. We will give a brief introduction to the subject. We will then show how to construct a Lipschitz time function in a simplified setting. We will end with a new result showing that the Aubry set is not an artifact of our proof of existence of time functions for stably causal manifolds.

  6. Seven Issues, Revisited

    OpenAIRE

    Whitehead, Jim; De Bra, Paul; Grønbæk, Kaj; Larsen, Deena; Legget, John; schraefel, monica m.c.

    2002-01-01

    It has been 15 years since the original presentation by Frank Halasz at Hypertext'87 on seven issues for the next generation of hypertext systems. These issues are: Search and Query Composites Virtual Structures Computation in/over hypertext network Versioning Collaborative Work Extensibility and Tailorability Since that time, these issues have formed the nucleus of multiple research agendas within the Hypertext community. Befitting this direction-setting role, the issues have been revisited ...

  7. Deterministic Graphical Games Revisited

    DEFF Research Database (Denmark)

    Andersson, Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro

    2008-01-01

    We revisit the deterministic graphical games of Washburn. A deterministic graphical game can be described as a simple stochastic game (a notion due to Anne Condon), except that we allow arbitrary real payoffs but disallow moves of chance. We study the complexity of solving deterministic graphical...... games and obtain an almost-linear time comparison-based algorithm for computing an equilibrium of such a game. The existence of a linear time comparison-based algorithm remains an open problem....

  8. Measurement of the Lyman-alpha radiation at ionization manometers for determination of the hydrogen atom number density in fusion experiments

    International Nuclear Information System (INIS)

    Loercher, M.

    1990-01-01

    Codes like DEGAS which simulate the interaction of neutral gas with plasma (e.g. in a divertor), not only deliver the global density and flux of neutral particles, but also allow one, in addition, to distinguish between atoms and molecules. Whereas the global parameters of the neutral gas in a divertor can be measured by, for example, special ion gauges like those, which are installed in the divertor chamber, there has until now been no possibility of measuring the atomic and molecular density independently. In the frame of a diploma thesis (M. Loercher) an ASDEX neutral pressure gauge was modified in such a way that it delivers not only the global density of neutral particles (molecules and atoms) by ionization, but also the density of the atoms by measurement of the Lα-radiation produced by electron impact exitation. Owing to the very weak intensity the main effort was dedicated to developing a detector-filter combination which allows the Lα-radiation to be separated from, the H 2 bands in the VUV and be measured with a time resolution of at least of few ms. Several versions were tested theoretically and practically. The best solution was found to be a combination of an O 2 filter using MgF 2 windows and a multichannel plate. The arrangement was tested and calibrated with an atomic beam of known intensity from an oven. (orig.)

  9. On the calculation of line strengths, oscillator strengths and lifetimes for very large principal quantum numbers in hydrogenic atoms and ions by the McLean–Watson formula

    International Nuclear Information System (INIS)

    Hey, J D

    2014-01-01

    As a sequel to an earlier study (Hey 2009 J. Phys. B: At. Mol. Opt. Phys. 42 125701), we consider further the application of the line strength formula derived by Watson (2006 J. Phys. B: At. Mol. Opt. Phys. 39 L291) to transitions arising from states of very high principal quantum number in hydrogenic atoms and ions (Rydberg–Rydberg transitions, n > 1000). It is shown how apparent difficulties associated with the use of recurrence relations, derived (Hey 2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641) by the ladder operator technique of Infeld and Hull (1951 Rev. Mod. Phys. 23 21), may be eliminated by a very simple numerical device, whereby this method may readily be applied up to n ≈ 10 000. Beyond this range, programming of the method may entail greater care and complexity. The use of the numerically efficient McLean–Watson formula for such cases is again illustrated by the determination of radiative lifetimes and comparison of present results with those from an asymptotic formula. The question of the influence on the results of the omission or inclusion of fine structure is considered by comparison with calculations based on the standard Condon–Shortley line strength formula. Interest in this work on the radial matrix elements for large n and n′ is related to measurements of radio recombination lines from tenuous space plasmas, e.g. Stepkin et al (2007 Mon. Not. R. Astron. Soc. 374 852), Bell et al (2011 Astrophys. Space Sci. 333 377), to the calculation of electron impact broadening parameters for such spectra (Watson 2006 J. Phys. B: At. Mol. Opt. Phys. 39 1889) and comparison with other theoretical methods (Peach 2014 Adv. Space Res. in press), to the modelling of physical processes in H II regions (Roshi et al 2012 Astrophys. J. 749 49), and the evaluation bound–bound transitions from states of high n during primordial cosmological recombination (Grin and Hirata 2010 Phys. Rev. D 81 083005, Ali-Haïmoud and Hirata 2010 Phys. Rev. D 82 063521

  10. Deterministic Graphical Games Revisited

    DEFF Research Database (Denmark)

    Andersson, Klas Olof Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro

    2012-01-01

    Starting from Zermelo’s classical formal treatment of chess, we trace through history the analysis of two-player win/lose/draw games with perfect information and potentially infinite play. Such chess-like games have appeared in many different research communities, and methods for solving them......, such as retrograde analysis, have been rediscovered independently. We then revisit Washburn’s deterministic graphical games (DGGs), a natural generalization of chess-like games to arbitrary zero-sum payoffs. We study the complexity of solving DGGs and obtain an almost-linear time comparison-based algorithm...

  11. Metamorphosis in Craniiformea revisited

    DEFF Research Database (Denmark)

    Altenburger, Andreas; Wanninger, Andreas; Holmer, Lars E.

    2013-01-01

    We revisited the brachiopod fold hypothesis and investigated metamorphosis in the craniiform brachiopod Novocrania anomala. Larval development is lecithotrophic and the dorsal (brachial) valve is secreted by dorsal epithelia. We found that the juvenile ventral valve, which consists only of a thin...... brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda...

  12. Revisiting fifth forces in the Galileon model

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Seery, David [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy

    2010-05-15

    A Galileon field is one which obeys a spacetime generalization of the non- relativistic Galilean invariance. Such a field may possess non-canonical kinetic terms, but ghost-free theories with a well-defined Cauchy problem exist, constructed using a finite number of relevant operators. The interactions of this scalar with matter are hidden by the Vainshtein effect, causing the Galileon to become weakly coupled near heavy sources. We revisit estimates of the fifth force mediated by a Galileon field, and show that the parameters of the model are less constrained by experiment than previously supposed. (orig.)

  13. 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

  14. Combination of the ionic-to-atomic line intensity ratios from two test elements for the diagnostic of plasma temperature and electron number density in Inductively Coupled Plasma Atomic Emission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tognoni, E. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)], E-mail: tognoni@ipcf.cnr.it; Hidalgo, M.; Canals, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia. Universidad de Alicante. Apdo. 99, 03080, Alicante (Spain); Cristoforetti, G.; Legnaioli, S.; Salvetti, A.; Palleschi, V. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)

    2007-05-15

    In Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) spectrochemical analysis, the MgII(280.270 nm)/MgI(285.213 nm) ionic to atomic line intensity ratio is commonly used as a monitor of the robustness of operating conditions. This approach is based on the univocal relationship existing between intensity ratio and plasma temperature, for a pure argon atmospheric ICP in thermodynamic equilibrium. In a multi-elemental plasma in the lower temperature range, the measurement of the intensity ratio may not be sufficient to characterize temperature and electron density. In such a range, the correct relationship between intensity ratio and plasma temperature can be calculated only when the complete plasma composition is known. We propose the combination of the line intensity ratios of two test elements (double ratio) as an effective diagnostic tool for a multi-elemental low temperature LTE plasma of unknown composition. In particular, the variation of the double ratio allows us discriminating changes in the plasma temperature from changes in the electron density. Thus, the effects on plasma excitation and ionization possibly caused by introduction of different samples and matrices in non-robust conditions can be more accurately interpreted. The method is illustrated by the measurement of plasma temperature and electron density in a specific analytic case.

  15. Revisiting Nursing Research in Nigeria

    African Journals Online (AJOL)

    2016-08-18

    Aug 18, 2016 ... health care research, it is therefore pertinent to revisit the state of nursing research in the country. .... platforms, updated libraries with electronic resource ... benchmarks for developing countries of 26%, [17] the amount is still ...

  16. Number series of atoms, interatomic bonds and interface bonds defining zinc-blende nanocrystals as function of size, shape and surface orientation: Analytic tools to interpret solid state spectroscopy data

    Directory of Open Access Journals (Sweden)

    Dirk König

    2016-08-01

    Full Text Available Semiconductor nanocrystals (NCs experience stress and charge transfer by embedding materials or ligands and impurity atoms. In return, the environment of NCs experiences a NC stress response which may lead to matrix deformation and propagated strain. Up to now, there is no universal gauge to evaluate the stress impact on NCs and their response as a function of NC size dNC. I deduce geometrical number series as analytical tools to obtain the number of NC atoms NNC(dNC[i], bonds between NC atoms Nbnd(dNC[i] and interface bonds NIF(dNC[i] for seven high symmetry zinc-blende (zb NCs with low-index faceting: {001} cubes, {111} octahedra, {110} dodecahedra, {001}-{111} pyramids, {111} tetrahedra, {111}-{001} quatrodecahedra and {001}-{111} quadrodecahedra. The fundamental insights into NC structures revealed here allow for major advancements in data interpretation and understanding of zb- and diamond-lattice based nanomaterials. The analytical number series can serve as a standard procedure for stress evaluation in solid state spectroscopy due to their deterministic nature, easy use and general applicability over a wide range of spectroscopy methods as well as NC sizes, forms and materials.

  17. Number series of atoms, interatomic bonds and interface bonds defining zinc-blende nanocrystals as function of size, shape and surface orientation: Analytic tools to interpret solid state spectroscopy data

    Energy Technology Data Exchange (ETDEWEB)

    König, Dirk, E-mail: dirk.koenig@unsw.edu.au [Integrated Materials Design Centre (IMDC) and School of Photovoltaic and Renewable Energy Engineering (SPREE), University of New South Wales, Sydney (Australia)

    2016-08-15

    Semiconductor nanocrystals (NCs) experience stress and charge transfer by embedding materials or ligands and impurity atoms. In return, the environment of NCs experiences a NC stress response which may lead to matrix deformation and propagated strain. Up to now, there is no universal gauge to evaluate the stress impact on NCs and their response as a function of NC size d{sub NC}. I deduce geometrical number series as analytical tools to obtain the number of NC atoms N{sub NC}(d{sub NC}[i]), bonds between NC atoms N{sub bnd}(d{sub NC}[i]) and interface bonds N{sub IF}(d{sub NC}[i]) for seven high symmetry zinc-blende (zb) NCs with low-index faceting: {001} cubes, {111} octahedra, {110} dodecahedra, {001}-{111} pyramids, {111} tetrahedra, {111}-{001} quatrodecahedra and {001}-{111} quadrodecahedra. The fundamental insights into NC structures revealed here allow for major advancements in data interpretation and understanding of zb- and diamond-lattice based nanomaterials. The analytical number series can serve as a standard procedure for stress evaluation in solid state spectroscopy due to their deterministic nature, easy use and general applicability over a wide range of spectroscopy methods as well as NC sizes, forms and materials.

  18. Circular revisit orbits design for responsive mission over a single target

    Science.gov (United States)

    Li, Taibo; Xiang, Junhua; Wang, Zhaokui; Zhang, Yulin

    2016-10-01

    The responsive orbits play a key role in addressing the mission of Operationally Responsive Space (ORS) because of their capabilities. These capabilities are usually focused on supporting specific targets as opposed to providing global coverage. One subtype of responsive orbits is repeat coverage orbit which is nearly circular in most remote sensing applications. This paper deals with a special kind of repeating ground track orbit, referred to as circular revisit orbit. Different from traditional repeat coverage orbits, a satellite on circular revisit orbit can visit a target site at both the ascending and descending stages in one revisit cycle. This typology of trajectory allows a halving of the traditional revisit time and does a favor to get useful information for responsive applications. However the previous reported numerical methods in some references often cost lots of computation or fail to obtain such orbits. To overcome this difficulty, an analytical method to determine the existence conditions of the solutions to revisit orbits is presented in this paper. To this end, the mathematical model of circular revisit orbit is established under the central gravity model and the J2 perturbation. A constraint function of the circular revisit orbit is introduced, and the monotonicity of that function has been studied. The existent conditions and the number of such orbits are naturally worked out. Taking the launch cost into consideration, optimal design model of circular revisit orbit is established to achieve a best orbit which visits a target twice a day in the morning and in the afternoon respectively for several days. The result shows that it is effective to apply circular revisit orbits in responsive application such as reconnoiter of natural disaster.

  19. Neutrino assisted GUT baryogenesis revisited

    Science.gov (United States)

    Huang, Wei-Chih; Päs, Heinrich; Zeißner, Sinan

    2018-03-01

    Many grand unified theory (GUT) models conserve the difference between the baryon and lepton number, B -L . These models can create baryon and lepton asymmetries from heavy Higgs or gauge boson decays with B +L ≠0 but with B -L =0 . Since the sphaleron processes violate B +L , such GUT-generated asymmetries will finally be washed out completely, making GUT baryogenesis scenarios incapable of reproducing the observed baryon asymmetry of the Universe. In this work, we revisit the idea to revive GUT baryogenesis, proposed by Fukugita and Yanagida, where right-handed neutrinos erase the lepton asymmetry before the sphaleron processes can significantly wash out the original B +L asymmetry, and in this way one can prevent a total washout of the initial baryon asymmetry. By solving the Boltzmann equations numerically for baryon and lepton asymmetries in a simplified 1 +1 flavor scenario, we can confirm the results of the original work. We further generalize the analysis to a more realistic scenario of three active and two right-handed neutrinos to highlight flavor effects of the right-handed neutrinos. Large regions in the parameter space of the Yukawa coupling and the right-handed neutrino mass featuring successful baryogenesis are identified.

  20. Life quality index revisited

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2004-01-01

    The derivation of the life quality index (LQI) is revisited for a revision. This revision takes into account the unpaid but necessary work time needed to stay alive in clean and healthy conditions to be fit for effective wealth producing work and to enjoyable free time. Dimension analysis...... at birth should not vary between countries. Finally the distributional assumptions are relaxed as compared to the assumptions made in an earlier work by the author. These assumptions concern the calculation of the life expectancy change due to the removal of an accident source. Moreover a simple public...... consistency problems with the standard power function expression of the LQI are pointed out. It is emphasized that the combination coefficient in the convex differential combination between the relative differential of the gross domestic product per capita and the relative differential of the expected life...

  1. Quantum duel revisited

    International Nuclear Information System (INIS)

    Schmidt, Alexandre G M; Paiva, Milena M

    2012-01-01

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α 1 and α 2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent. (paper)

  2. Satellite failures revisited

    Science.gov (United States)

    Balcerak, Ernie

    2012-12-01

    In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

  3. Logistics Innovation Process Revisited

    DEFF Research Database (Denmark)

    Gammelgaard, Britta; Su, Shong-Iee Ivan; Yang, Su-Lan

    2011-01-01

    Purpose – The purpose of this paper is to learn more about logistics innovation processes and their implications for the focal organization as well as the supply chain, especially suppliers. Design/methodology/approach – The empirical basis of the study is a longitudinal action research project...... that was triggered by the practical needs of new ways of handling material flows of a hospital. This approach made it possible to revisit theory on logistics innovation process. Findings – Apart from the tangible benefits reported to the case hospital, five findings can be extracted from this study: the logistics...... innovation process model may include not just customers but also suppliers; logistics innovation in buyer-supplier relations may serve as an alternative to outsourcing; logistics innovation processes are dynamic and may improve supplier partnerships; logistics innovations in the supply chain are as dependent...

  4. Klein's double discontinuity revisited

    DEFF Research Database (Denmark)

    Winsløw, Carl; Grønbæk, Niels

    2014-01-01

    Much effort and research has been invested into understanding and bridging the ‘gaps’ which many students experience in terms of contents and expectations as they begin university studies with a heavy component of mathematics, typically in the form of calculus courses. We have several studies...... of bridging measures, success rates and many other aspects of these “entrance transition” problems. In this paper, we consider the inverse transition, experienced by university students as they revisit core parts of high school mathematics (in particular, calculus) after completing the undergraduate...... mathematics courses which are mandatory to become a high school teacher of mathematics. To what extent does the “advanced” experience enable them to approach the high school calculus in a deeper and more autonomous way ? To what extent can “capstone” courses support such an approach ? How could it be hindered...

  5. Reframing in dentistry: Revisited

    Directory of Open Access Journals (Sweden)

    Sivakumar Nuvvula

    2013-01-01

    Full Text Available The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child′s behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice.

  6. Development of constraint algorithm for the number of electrons in molecular orbitals consisting mainly 4f atomic orbitals of rare-earth elements and its introduction to tight-binding quantum chemical molecular dynamics method

    International Nuclear Information System (INIS)

    Endou, Akira; Onuma, Hiroaki; Jung, Sun-ho

    2007-01-01

    Our original tight-binding quantum chemical molecular dynamics code, Colors', has been successfully applied to the theoretical investigation of complex materials including rare-earth elements, e.g., metal catalysts supported on a CeO 2 surface. To expand our code so as to obtain a good convergence for the electronic structure of a calculation system including a rare-earth element, we developed a novel algorithm to provide a constraint condition for the number of electrons occupying the selected molecular orbitals that mainly consist of 4f atomic orbitals of the rare-earth element. This novel algorithm was introduced in Colors. Using Colors, we succeeded in obtaining the classified electronic configurations of the 4f atomic orbitals of Ce 4+ and reduced Ce ions in a CeO 2 bulk model with one oxygen defect, which makes it difficult to obtain a good convergence using a conventional first-principles quantum chemical calculation code. (author)

  7. The electron-impact ionization of Ar and Kr revisited: A critical analysis of double-to-single ionization cross section ratio measurements using the fast-atom-beam technique

    International Nuclear Information System (INIS)

    Tarnovsky, V.; Becker, K.

    1992-01-01

    We report new measurements of the absolute electron-impact double ionization cross sections for Ar and Kr and of the ratios of double-to-single ionization for impact energies from threshold to 200 eV using the crossed electron-beam - fast-atom-beam technique. The work was motivated by the recently highlighted spread of about 30% in the Ar 2+ /Ar + ionization cross section ratios obtained by several groups using different experimental techniques. Such a spread is inconsistent with statistical uncertainties of typically 3% or less that were quoted for the various reported ratios. A similar situation exists for Kr where the spread among the recently published Kr 2+ /Kr + ionization cross section ratios is about 15%. We made an attempt to identify all potential systematic errors inherent to the fast-beam technique that could affect the measurement of cross section ratios with special emphasis on those systematic errors that could influence the detection of singly and doubly charged product ions differently. We found Ar 2+ /Ar + and Kr 2+ /Kr + cross section ratios of, respectively 0.066±0.007 and 0.087±0.008 at 100 eV which confirm earlier measurements using the same experimental technique. The error limits on cross sections ratios of multiple-to-single ionization for the same target atom and at least ±10% for ratios of single ionization cross sections for different target species. Our error limits are dominated by systematic uncertainties of the apparatus which do not cancel when cross section ratios are measured, since the ratios are obtained under similar, but not identical experimental conditions. (orig.)

  8. Microstructure-sensitive modelling of dislocation creep in polycrystalline FCC alloys: Orowan theory revisited

    Energy Technology Data Exchange (ETDEWEB)

    Galindo-Nava, E.I., E-mail: eg375@cam.ac.uk; Rae, C.M.F.

    2016-01-10

    A new approach for modelling dislocation creep during primary and secondary creep in FCC metals is proposed. The Orowan equation and dislocation behaviour at the grain scale are revisited to include the effects of different microstructures such as the grain size and solute atoms. Dislocation activity is proposed to follow a jog-diffusion law. It is shown that the activation energy for cross-slip E{sub cs} controls dislocation mobility and the strain increments during secondary creep. This is confirmed by successfully comparing E{sub cs} with the experimentally determined activation energy during secondary creep in 5 FCC metals. It is shown that the inverse relationship between the grain size and dislocation creep is attributed to the higher number of strain increments at the grain level dominating their magnitude as the grain size decreases. An alternative approach describing solid solution strengthening effects in nickel alloys is presented, where the dislocation mobility is reduced by dislocation pinning around solute atoms. An analysis on the solid solution strengthening effects of typical elements employed in Ni-base superalloys is also discussed. The model results are validated against measurements of Cu, Ni, Ti and 4 Ni-base alloys for wide deformation conditions and different grain sizes.

  9. 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)

  10. Time-resolved study of the electron temperature and number density of argon metastable atoms in argon-based dielectric barrier discharges

    Science.gov (United States)

    Desjardins, E.; Laurent, M.; Durocher-Jean, A.; Laroche, G.; Gherardi, N.; Naudé, N.; Stafford, L.

    2018-01-01

    A combination of optical emission spectroscopy and collisional-radiative modelling is used to determine the time-resolved electron temperature (assuming Maxwellian electron energy distribution function) and number density of Ar 1s states in atmospheric pressure Ar-based dielectric barrier discharges in presence of either NH3 or ethyl lactate. In both cases, T e values were higher early in the discharge cycle (around 0.8 eV), decreased down to about 0.35 eV with the rise of the discharge current, and then remained fairly constant during discharge extinction. The opposite behaviour was observed for Ar 1s states, with cycle-averaged values in the 1017 m-3 range. Based on these findings, a link was established between the discharge ionization kinetics (and thus the electron temperature) and the number density of Ar 1s state.

  11. Energy dependence of effective atomic numbers for photon energy absorption and photon interaction: Studies of some biological molecules in the energy range 1 keV-20 MeV

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2008-01-01

    Effective atomic numbers for photon energy absorption, Z(PEA,eff), and for photon interaction, Z(PI,eff), have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for biological molecules, such as fatty acids (lauric, myristic, palmitic, stearic, oleic, linoleic......, linolenic, arachidonic, and arachidic acids), nucleotide bases (adenine, guanine, cytosine, uracil, and thymine), and carbohydrates (glucose, sucrose, raffinose, and starch). The Z(PEA, eff) and Z(PI, eff) values have been found to change with energy and composition of the biological molecules. The energy...

  12. Kβ/Kα X-ray intensity ratios for some elements in the atomic number range 28≤Z≤39 at 16.896 keV

    Directory of Open Access Journals (Sweden)

    R. Yılmaz

    2017-07-01

    Full Text Available The K shell intensity ratios (Kβ/Kα have been experimentally determined for some elements in the atomic number range 28 ≤ Z ≤ 39 by using secondary excitation method. K X-rays emitted by samples have been counted by a Si (Li detector with 160 eV resolutions at 5.9 keV. The measured values were compared with the theoretical and experimental values. In general, the values obtained are in good agreement with the calculated values.

  13. The Lanthanide Contraction Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, Michael; Oliver, Allen G.; Raymond, Kenneth N.

    2007-04-19

    A complete, isostructural series of lanthanide complexes (except Pm) with the ligand TREN-1,2-HOIQO has been synthesized and structurally characterized by means of single-crystal X-ray analysis. All complexes are 1D-polymeric species in the solid state, with the lanthanide being in an eight-coordinate, distorted trigonal-dodecahedral environment with a donor set of eight unique oxygen atoms. This series constitutes the first complete set of isostructural lanthanide complexes with a ligand of denticity greater than two. The geometric arrangement of the chelating moieties slightly deviates across the lanthanide series, as analyzed by a shape parameter metric based on the comparison of the dihedral angles along all edges of the coordination polyhedron. The apparent lanthanide contraction in the individual Ln-O bond lengths deviates considerably from the expected quadratic decrease that was found previously in a number of complexes with ligands of low denticity. The sum of all bond lengths around the trivalent metal cation, however, is more regular, showing an almost ideal quadratic behavior across the entire series. The quadratic nature of the lanthanide contraction is derived theoretically from Slater's model for the calculation of ionic radii. In addition, the sum of all distances along the edges of the coordination polyhedron show exactly the same quadratic dependency as the Ln-X bond lengths. The universal validity of this coordination sphere contraction, concomitant with the quadratic decrease in Ln-X bond lengths, was confirmed by reexamination of four other, previously published, almost complete series of lanthanide complexes. Due to the importance of multidentate ligands for the chelation of rare-earth metals, this result provides a significant advance for the prediction and rationalization of the geometric features of the corresponding lanthanide complexes, with great potential impact for all aspects of lanthanide coordination.

  14. The critical catastrophe revisited

    International Nuclear Information System (INIS)

    De Mulatier, Clélia; Rosso, Alberto; Dumonteil, Eric; Zoia, Andrea

    2015-01-01

    The neutron population in a prototype model of nuclear reactor can be described in terms of a collection of particles confined in a box and undergoing three key random mechanisms: diffusion, reproduction due to fissions, and death due to absorption events. When the reactor is operated at the critical point, and fissions are exactly compensated by absorptions, the whole neutron population might in principle go to extinction because of the wild fluctuations induced by births and deaths. This phenomenon, which has been named critical catastrophe, is nonetheless never observed in practice: feedback mechanisms acting on the total population, such as human intervention, have a stabilizing effect. In this work, we revisit the critical catastrophe by investigating the spatial behaviour of the fluctuations in a confined geometry. When the system is free to evolve, the neutrons may display a wild patchiness (clustering). On the contrary, imposing a population control on the total population acts also against the local fluctuations, and may thus inhibit the spatial clustering. The effectiveness of population control in quenching spatial fluctuations will be shown to depend on the competition between the mixing time of the neutrons (i.e. the average time taken for a particle to explore the finite viable space) and the extinction time

  15. Magnetic moments revisited

    International Nuclear Information System (INIS)

    Towner, I.S.; Khanna, F.C.

    1984-01-01

    Consideration of core polarization, isobar currents and meson-exchange processes gives a satisfactory understanding of the ground-state magnetic moments in closed-shell-plus (or minus)-one nuclei, A = 3, 15, 17, 39 and 41. Ever since the earliest days of the nuclear shell model the understanding of magnetic moments of nuclear states of supposedly simple configurations, such as doubly closed LS shells +-1 nucleon, has been a challenge for theorists. The experimental moments, which in most cases are known with extraordinary precision, show a small yet significant departure from the single-particle Schmidt values. The departure, however, is difficult to evaluate precisely since, as will be seen, it results from a sensitive cancellation between several competing corrections each of which can be as large as the observed discrepancy. This, then, is the continuing fascination of magnetic moments. In this contribution, we revisit the subjet principally to identify the role played by isobar currents, which are of much concern at this conference. But in so doing we warn quite strongly of the dangers of considering just isobar currents in isolation; equal consideration must be given to competing processes which in this context are the mundane nuclear structure effects, such as core polarization, and the more popular meson-exchange currents

  16. Lorentz violation naturalness revisited

    Energy Technology Data Exchange (ETDEWEB)

    Belenchia, Alessio; Gambassi, Andrea; Liberati, Stefano [SISSA - International School for Advanced Studies, via Bonomea 265, 34136 Trieste (Italy); INFN, Sezione di Trieste, via Valerio 2, 34127 Trieste (Italy)

    2016-06-08

    We revisit here the naturalness problem of Lorentz invariance violations on a simple toy model of a scalar field coupled to a fermion field via a Yukawa interaction. We first review some well-known results concerning the low-energy percolation of Lorentz violation from high energies, presenting some details of the analysis not explicitly discussed in the literature and discussing some previously unnoticed subtleties. We then show how a separation between the scale of validity of the effective field theory and that one of Lorentz invariance violations can hinder this low-energy percolation. While such protection mechanism was previously considered in the literature, we provide here a simple illustration of how it works and of its general features. Finally, we consider a case in which dissipation is present, showing that the dissipative behaviour does not percolate generically to lower mass dimension operators albeit dispersion does. Moreover, we show that a scale separation can protect from unsuppressed low-energy percolation also in this case.

  17. Generalized Pauli constraints in small atoms

    DEFF Research Database (Denmark)

    Schilling, Christian; Altunbulak, Murat; Knecht, Stefan

    2018-01-01

    investigations have found evidence that these constraints are exactly saturated in several physically relevant systems, e.g., in a certain electronic state of the beryllium atom. It has been suggested that, in such cases, the constraints, rather than the details of the Hamiltonian, dictate the system......'s qualitative behavior. Here, we revisit this question with state-of-the-art numerical methods for small atoms. We find that the constraints are, in fact, not exactly saturated, but that they lie much closer to the surface defined by the constraints than the geometry of the problem would suggest. While...

  18. 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.)

  19. Leadership and Management Theories Revisited

    DEFF Research Database (Denmark)

    Madsen, Mona Toft

    2001-01-01

    The goal of the paper is to revisit and analyze key contributions to the understanding of leadership and management. As a part of the discussion a role perspective that allows for additional and/or integrated leader dimensions, including a change-centered, will be outlined. Seemingly, a major...

  20. Revisiting Inter-Genre Similarity

    DEFF Research Database (Denmark)

    Sturm, Bob L.; Gouyon, Fabien

    2013-01-01

    We revisit the idea of ``inter-genre similarity'' (IGS) for machine learning in general, and music genre recognition in particular. We show analytically that the probability of error for IGS is higher than naive Bayes classification with zero-one loss (NB). We show empirically that IGS does...... not perform well, even for data that satisfies all its assumptions....

  1. 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.)

  2. 'Counterfeit deviance' revisited.

    Science.gov (United States)

    Griffiths, Dorothy; Hingsburger, Dave; Hoath, Jordan; Ioannou, Stephanie

    2013-09-01

    The field has seen a renewed interest in exploring the theory of 'counterfeit deviance' for persons with intellectual disability who sexually offend. The term was first presented in 1991 by Hingsburger, Griffiths and Quinsey as a means to differentiate in clinical assessment a subgroup of persons with intellectual disability whose behaviours appeared like paraphilia but served a function that was not related to paraphilia sexual urges or fantasies. Case observations were put forward to provide differential diagnosis of paraphilia in persons with intellectual disabilities compared to those with counterfeit deviance. The brief paper was published in a journal that is no longer available and as such much of what is currently written on the topic is based on secondary sources. The current paper presents a theoretical piece to revisit the original counterfeit deviance theory to clarify the myths and misconceptions that have arisen and evaluate the theory based on additional research and clinical findings. The authors also propose areas where there may be a basis for expansion of the theory. The theory of counterfeit deviance still has relevance as a consideration for clinicians when assessing the nature of a sexual offence committed by a person with an intellectual disability. Clinical differentiation of paraphilia from counterfeit deviance provides a foundation for intervention that is designed to specifically treat the underlying factors that contributed to the offence for a given individual. Counterfeit deviance is a concept that continues to provide areas for consideration for clinicians regarding the assessment and treatment of an individual with an intellectual disability who has sexually offended. It is not and never was an explanation for all sexually offending behavior among persons with intellectual disabilities. © 2013 John Wiley & Sons Ltd.

  3. Gaussian entanglement revisited

    Science.gov (United States)

    Lami, Ludovico; Serafini, Alessio; Adesso, Gerardo

    2018-02-01

    We present a novel approach to the separability problem for Gaussian quantum states of bosonic continuous variable systems. We derive a simplified necessary and sufficient separability criterion for arbitrary Gaussian states of m versus n modes, which relies on convex optimisation over marginal covariance matrices on one subsystem only. We further revisit the currently known results stating the equivalence between separability and positive partial transposition (PPT) for specific classes of Gaussian states. Using techniques based on matrix analysis, such as Schur complements and matrix means, we then provide a unified treatment and compact proofs of all these results. In particular, we recover the PPT-separability equivalence for: (i) Gaussian states of 1 versus n modes; and (ii) isotropic Gaussian states. In passing, we also retrieve (iii) the recently established equivalence between separability of a Gaussian state and and its complete Gaussian extendability. Our techniques are then applied to progress beyond the state of the art. We prove that: (iv) Gaussian states that are invariant under partial transposition are necessarily separable; (v) the PPT criterion is necessary and sufficient for separability for Gaussian states of m versus n modes that are symmetric under the exchange of any two modes belonging to one of the parties; and (vi) Gaussian states which remain PPT under passive optical operations can not be entangled by them either. This is not a foregone conclusion per se (since Gaussian bound entangled states do exist) and settles a question that had been left unanswered in the existing literature on the subject. This paper, enjoyable by both the quantum optics and the matrix analysis communities, overall delivers technical and conceptual advances which are likely to be useful for further applications in continuous variable quantum information theory, beyond the separability problem.

  4. Izmit Foreshocks Revisited

    Science.gov (United States)

    Ellsworth, W. L.; Bulut, F.

    2016-12-01

    Much of what we know about the initiation of earthquakes comes from the temporal and spatial relationship of foreshocks to the initiation point of the mainshock. The 1999 Mw 7.6 Izmit, Turkey, earthquake was preceded by a 44 minute-long foreshock sequence. Bouchon et al. (Science, 2011) analyzed the foreshocks using a single seismic station, UCG, located to the north of the east-west fault, and concluded on the basis of waveform similarity that the foreshocks repeatedly re-ruptured the same fault patch, driven by slow slip at the base of the crust. We revisit the foreshock sequence using seismograms from 9 additional stations that recorded the four largest foreshocks (Mw 2.0 to 2.8) to better characterize spatial and temporal evolution of the foreshock sequence and their relationship to the mainshock hypocenter. Cross-correlation timing and hypocentroid location with hypoDD reveals a systematic west-to-east propagation of the four largest foreshocks toward the mainshock hypocenter. Foreshock rupture dimensions estimated using spectral ratios imply no major overlap for the first three foreshocks. The centroid of 4th and largest foreshock continues the eastward migration, but lies within the circular source area of the 3rd. The 3rd, however, has a low stress drop and strong directivity to the west . The mainshock hypocenter locates on the eastern edge of foreshock 4. We also re-analyzed waveform similarity of all 18 foreshocks recorded at UCG by removing the common mode signal and clustering the residual seismogram using the correlation coefficient as the distance metric. The smaller foreshocks cluster with the larger events in time order, sometimes as foreshocks and more commonly as aftershocks. These observations show that the Izmit foreshock sequence is consistent with a stress-transfer driven cascade, moving systematically to the east along the fault and that there is no observational requirement for creep as a driving mechanism.

  5. 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)

  6. Bohr orbit theory revisited

    International Nuclear Information System (INIS)

    Harcourt, R.D.

    1987-01-01

    Bohr orbit theory is used to calculate energies for the 1S, 2P, 3D, 4F and 5G states of the helium muonic atom, when the muon is excited. These energies are close to those which have been calculated variationally by Huang (1977, Phys. Rev. A 15 1832-8). (author)

  7. The Unimolecular Reactions of CF3CHF2 Studied by Chemical Activation: Assignment of Rate Constants and Threshold Energies to the 1,2-H Atom Transfer, 1,1-HF and 1,2-HF Elimination Reactions, and the Dependence of Threshold Energies on the Number of F-Atom Substituents in the Fluoroethane Molecules.

    Science.gov (United States)

    Smith, Caleb A; Gillespie, Blanton R; Heard, George L; Setser, D W; Holmes, Bert E

    2017-11-22

    The recombination of CF 3 and CHF 2 radicals in a room-temperature bath gas was used to prepare vibrationally excited CF 3 CHF 2 * molecules with 101 kcal mol -1 of vibrational energy. The subsequent 1,2-H atom transfer and 1,1-HF and 1,2-HF elimination reactions were observed as a function of bath gas pressure by following the CHF 3 , CF 3 (F)C: and C 2 F 4 product concentrations by gas chromatography using a mass spectrometer as the detector. The singlet CF 3 (F)C: concentration was measured by trapping the carbene with trans-2-butene. The experimental rate constants are 3.6 × 10 4 , 4.7 × 10 4 , and 1.1 × 10 4 s -1 for the 1,2-H atom transfer and 1,1-HF and 1,2-HF elimination reactions, respectively. These experimental rate constants were matched to statistical RRKM calculated rate constants to assign threshold energies (E 0 ) of 88 ± 2, 88 ± 2, and 87 ± 2 kcal mol -1 to the three reactions. Pentafluoroethane is the only fluoroethane that has a competitive H atom transfer decomposition reaction, and it is the only example with 1,1-HF elimination being more important than 1,2-HF elimination. The trend of increasing threshold energies for both 1,1-HF and 1,2-HF processes with the number of F atoms in the fluoroethane molecule is summarized and investigated with electronic-structure calculations. Examination of the intrinsic reaction coordinate associated with the 1,1-HF elimination reaction found an adduct between CF 3 (F)C: and HF in the exit channel with a dissociation energy of ∼5 kcal mol -1 . Hydrogen-bonded complexes between HF and the H atom migration transition state of CH 3 (F)C: and the F atom migration transition state of CF 3 (F)C: also were found by the calculations. The role that these carbene-HF complexes could play in 1,1-HF elimination reactions is discussed.

  8. Number-phase entropic squeezing and nonclassical properties of a three-level atom interacting with a two-mode field: intensity-dependent coupling, deformed Kerr medium, and detuning effects

    Science.gov (United States)

    Faghihi, Mohammad Javad; Tavassoly, Mohammad Kazem

    2013-11-01

    In this paper, we follow our presented model in J. Opt. Soc. Am. B {\\bf 30}, 1109--1117 (2013), in which the interaction between a $\\Lambda$-type three-level atom and a quantized two-mode radiation field in a cavity in the presence of nonlinearities is studied. After giving a brief review on the procedure of obtaining the state vector of the atom-field system, some further interesting and important physical features (which are of particular interest in the quantum optics field of research) of the whole system state, i.e., the number-phase entropic uncertainty relation (based on the two-mode Pegg-Barnett formalism) and some of the nonclassicality signs consist of sub-Poissonian statistics, Cauchy-Schwartz inequality and two kinds of squeezing phenomenon are investigated. During our presentation, the effects of intensity-dependent coupling, deformed Kerr medium and the detuning parameters on the depth and domain of each of the mentioned nonclassical criteria of the considered quantum system are studied, in detail. It is shown that each of the mentioned nonclassicality aspects can be obtained by appropriately choosing the related parameters.

  9. Investigation of the effective atomic numbers of dosimetric materials for electrons, protons and alpha particles using a direct method in the energy region 10 keV-1 GeV: a comparative study.

    Science.gov (United States)

    Kurudirek, Murat; Aksakal, Oğuz; Akkuş, Tuba

    2015-11-01

    A direct method has been used for the first time, to compute effective atomic numbers (Z eff) of water, air, human tissues, and some organic and inorganic compounds, for total electron proton and alpha particle interaction in the energy region 10 keV-1 GeV. The obtained values for Z eff were then compared to those obtained using an interpolation procedure. In general, good agreement has been observed for electrons, and the difference (%) in Z eff between the results of the direct and the interpolation method was found to be energy range from 10 keV to 1 MeV. More specifically, results of the two methods were found to agree well (Dif. energy region with respect to the total electron interaction. On the other hand, values for Z eff calculated using both methods for protons and alpha particles generally agree with each other in the high-energy region above 10 MeV.

  10. Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study

    International Nuclear Information System (INIS)

    Kurudirek, Murat

    2014-01-01

    Highlights: • Radiation shielding calculations for concretes and glass systems. • Assigning effective atomic number for the given materials for total electron interaction. • Glass systems generally have better shielding ability than concretes. - Abstract: Concrete has been widely used as a radiation shielding material due to its extremely low cost. On the other hand, glass systems, which make everything inside visible to observers, are considered as promising shielding materials as well. In the present work, the effective atomic numbers, Z eff of some concretes and glass systems (industrial waste containing glass, Pb base glass and non-Pb base glass) have been calculated for total electron interaction in the energy region of 10 keV–1 GeV. Also, the continuous slowing down approximation (CSDA) ranges for the given materials have been calculated in the wide energy region to show the shielding effectiveness of the given materials. The glass systems are not only compared to different types of concretes but also compared to the lead base glass systems in terms of shielding. Moreover, the obtained results for total electron interaction have been compared to the results for total photon interaction wherever possible. In general, it has been observed that the glass systems have superior properties than most of the concretes over the high-energy region with respect to the electron interaction. Also, glass systems without lead show better electron stopping than lead base glasses at some energy regions as well. Along with the photon attenuation capability, it is seen that Fly Ash base glass systems have not only greater electron stopping capability but also have greater photon attenuation especially in high energy region when compared with standard shielding concretes

  11. Mass attenuation coefficient (μ/ρ), effective atomic number (Z{sub eff}) and measurement of x-ray energy spectra using based calcium phosphate biomaterials: a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes Z, M. A.; Da Silva, T. A.; Nogueira, M. S. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Pte. Antonio Carlos 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil); Goncalves Z, E., E-mail: madelon@cdtn.br [Pontifice Catholic University of Minas Gerais, Av. Dom Jose Gaspar 500, Belo Horizonte 30535-901, Minas Gerais (Brazil)

    2015-10-15

    In dentistry, alveolar bone regeneration procedures using based calcium phosphate biomaterials have been shown effective. However,there are not reports in the literature of studies the interaction of low energy radiation in these biomaterials used as attenuator and not being then allowed a comparison between the theoretical values and experimental.The objective of this study was to determine the interaction of radiation parameters of four dental biomaterials - BioOss, Cerasorb M Dental, Straumann Boneceramic and Osteogen for diagnostic radiology qualities. As a material and methods, the composition of the biomaterials was determined by the analytical techniques. The samples with 0.181 cm to 0,297 cm thickness were experimentally used as attenuators for the measurement of the transmitted X-rays spectra in X-ray equipment with 50 to 90 kV range by spectrometric system comprising the Cd Te detector. After this procedure, the mass attenuation coefficient, the effective atomic number were determined and compared between all the specimens analyzed, using the program WinXCOM in the range of 10 to 200 keV. In all strains examined observed that the energy spectrum of x-rays transmitted through the BioOss has the mean energy slightly smaller than the others biomaterials for close thickness. The μ/ρ and Z{sub eff} of the biomaterials showed its dependence on photon energy and atomic number of the elements of the material analyzed. It is concluded according to the methodology employed in this study that the measurements of x-ray spectrum, μ/ρ and Z{sub eff} using biomaterials as attenuators confirmed that the thickness, density, composition of the samples, the incident photon energy are factors that determine the characteristics of radiation in a tissue or equivalent material. (Author)

  12. Effective atomic number, energy loss and radiation damage studies in some materials commonly used in nuclear applications for heavy charged particles such as H, C, Mg, Fe, Te, Pb and U

    Science.gov (United States)

    Kurudirek, Murat

    2016-05-01

    Commonly used nuclear physics materials such as water, concrete, Pb-glass, paraffin, freon and P 10 gases, some alloys such as brass, bronze, stainless-steel and some scintillators such as anthracene, stilbene and toluene have been investigated with respect to the heavy charged particle interaction as means of projected range and effective atomic number (Zeff) in the energy region 10 keV to 10 MeV. Calculations were performed for heavy ions such as H, C, Mg, Fe, Te, Pb and U. Also, the energy loss and radiation damage were studied using SRIM Monte Carlo code for anthracene for different heavy ions of 100 keV kinetic energy. It has been observed that the variation in Zeff becomes less when the atomic number of the ions increase. Glass-Pb, bronze, brass, stainless-steel and Freon gas were found to vary less than 10% in the energy region 10 keV to 10 MeV. For total proton interaction, discrepancies up to 10% and 18% between two databases namely PSTAR and SRIM were noted in mass stopping power and Zeff of water, respectively. The range calculations resulted with a conclusion that the metal alloys and glass-Pb have lowest values of ranges confirming best shielding against energetic heavy ions whereas freon and P 10 gases have the highest values of ranges in the entire energy region. The simulation results showed that the energy loss (%) to target electrons decreases as the Z of the incident ion increases. Also, it was observed that the radiation damage first increases with Z of the ion and then keeps almost constant for ions with Z≥52.

  13. Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Kurudirek, Murat, E-mail: mkurudirek@gmail.com

    2014-12-15

    Highlights: • Radiation shielding calculations for concretes and glass systems. • Assigning effective atomic number for the given materials for total electron interaction. • Glass systems generally have better shielding ability than concretes. - Abstract: Concrete has been widely used as a radiation shielding material due to its extremely low cost. On the other hand, glass systems, which make everything inside visible to observers, are considered as promising shielding materials as well. In the present work, the effective atomic numbers, Z{sub eff} of some concretes and glass systems (industrial waste containing glass, Pb base glass and non-Pb base glass) have been calculated for total electron interaction in the energy region of 10 keV–1 GeV. Also, the continuous slowing down approximation (CSDA) ranges for the given materials have been calculated in the wide energy region to show the shielding effectiveness of the given materials. The glass systems are not only compared to different types of concretes but also compared to the lead base glass systems in terms of shielding. Moreover, the obtained results for total electron interaction have been compared to the results for total photon interaction wherever possible. In general, it has been observed that the glass systems have superior properties than most of the concretes over the high-energy region with respect to the electron interaction. Also, glass systems without lead show better electron stopping than lead base glasses at some energy regions as well. Along with the photon attenuation capability, it is seen that Fly Ash base glass systems have not only greater electron stopping capability but also have greater photon attenuation especially in high energy region when compared with standard shielding concretes.

  14. Dynamic Topography Revisited

    Science.gov (United States)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

  15. Remembered Experiences and Revisit Intentions

    DEFF Research Database (Denmark)

    Barnes, Stuart; Mattsson, Jan; Sørensen, Flemming

    2016-01-01

    Tourism is an experience-intensive sector in which customers seek and pay for experiences above everything else. Remembering past tourism experiences is also crucial for an understanding of the present, including the predicted behaviours of visitors to tourist destinations. We adopt a longitudinal...... approach to memory data collection from psychological science, which has the potential to contribute to our understanding of tourist behaviour. In this study, we examine the impact of remembered tourist experiences in a safari park. In particular, using matched survey data collected longitudinally and PLS...... path modelling, we examine the impact of positive affect tourist experiences on the development of revisit intentions. We find that longer-term remembered experiences have the strongest impact on revisit intentions, more so than predicted or immediate memory after an event. We also find that remembered...

  16. Atomic physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  17. 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.)

  18. Revisiting Mutual Fund Performance Evaluation

    OpenAIRE

    Angelidis, Timotheos; Giamouridis, Daniel; Tessaromatis, Nikolaos

    2012-01-01

    Mutual fund manager excess performance should be measured relative to their self-reported benchmark rather than the return of a passive portfolio with the same risk characteristics. Ignoring the self-reported benchmark introduces biases in the measurement of stock selection and timing components of excess performance. We revisit baseline empirical evidence in mutual fund performance evaluation utilizing stock selection and timing measures that address these biases. We introduce a new factor e...

  19. 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...

  20. 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...

  1. Ubiquitous atom

    International Nuclear Information System (INIS)

    Spruch, G.M.; Spruch, L.

    1974-01-01

    The fundamentals of modern physics, including the basic physics and chemistry of the atom, elementary particles, cosmology, periodicity, and recent advances, are surveyed. The biology and chemistry of the life process is discussed to provide a background for considering the effects of atomic particles on living things. The uses of atomic power in space travel, merchant shipping, food preservation, desalination, and nuclear clocks are explored. (Pollut. Abstr.)

  2. 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

  3. Radiogenic leukemia revisited

    International Nuclear Information System (INIS)

    Moloney, W.C.

    1987-01-01

    Radiation-induced leukemia is considered to be similar to the de novo disease. However, following an analysis of clinical and hematological findings in leukemia occurring in irradiated cervical cancer patients, adult Japanese atomic-bomb survivors, and spondylitics treated with x-ray, striking differences were noted. Acute leukemias in cervical cancer patients and Japanese survivors were similar in type to acute de novo leukemias in adults. Cell types among spondylitics were very dissimilar; rare forms, eg, acute erythromyelocytic leukemia (AEL) and acute megakaryocytic leukemia, were increased. Pancytopenia occurred in 25 of 35 cases and erythromyelodysplastic disorders were noted in seven of 35 acute cases. The leukemias and myelodysplastic disorders closely resembled those occurring in patients treated with alkylating agents. This similarity suggests a common pathogenesis involving marrow stem cell injury and extra-medullary mediators of hematopoiesis. Investigation of early acute leukemias and myelodysplastic disorders with newer techniques may provide valuable insights into the pathogenesis of leukemia in humans

  4. Copper doped borate dosimeters revisited

    Energy Technology Data Exchange (ETDEWEB)

    Alajerami, Y.S.M. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Department of Medical Radiography, Al-Azhar University, Gaza Strip, Palestine (Country Unknown); Hashim, S., E-mail: suhairul@utm.my [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Oncology Treatment Centre, Sultan Ismail Hospital, 81100 Johor Bahru (Malaysia); Ghoshal, S.K. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Bradley, D.A. [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Mhareb, M. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Saleh, M.A. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); National Atomic Energy Commission (NATEC), Sana' a (Yemen)

    2014-11-15

    We render a panoramic overview on copper (Cu) doped borate dosimeters. Preparing a dosimeter by mixing specific materials with precise weights and methods is a never-ending quest. The recommended composition is highly decisive for accurate estimation of the absorbed dose, prediction of the biological outcome, determination of the treatment dose for radiation therapy and facilitation of personal monitoring. Based on these principles, the proposed dosimeter must cover a series of dosimetric properties to realize the exact results and assessment. The doped borate dosimeters indeed demonstrate attractive thermoluminescence (TL) features. Several dedicated efforts are attempted to improve the luminescence properties by doping various transition metals or rare-earth elements. The Cu ion being one of the preferred activators shows excellent TL properties as revealed via detail comparison with other dosimeters. Two oxide states of Cu (Cu{sup +} and Cu{sup ++}) with reasonable atomic number allow easy interaction with boron network. Interestingly, the intrinsic luminescent centers of borate lattice are in cross linked with that of Cu{sup +} ions. Thus, the activation of borate dosimeter with Cu ions for the enhancement of the TL sensitivity is recognized. These dosimeters reveal similar glow curves as the standard TLD-100 (LiF:Mg,Ti) one irrespective of the use of modifiers and synthesis techniques. They display high sensitivity, low fading, dose response linearity over wide range and practical minimum detectable dose. Furthermore, the effective atomic number being the most beneficial aspect (equivalent to that of human tissue) of borate dosimeters do not show any change due to Cu ion activations. The past development, major challenges, excitement, applications, recent progress and the future promises of Cu doped borate TL dosimeters are highlighted. - Highlights: • The manuscript gives a panoramic overview on copper doped borate dosimeters. • Cu ions activated

  5. Copper doped borate dosimeters revisited

    International Nuclear Information System (INIS)

    Alajerami, Y.S.M.; Hashim, S.; Ghoshal, S.K.; Bradley, D.A.; Mhareb, M.; Saleh, M.A.

    2014-01-01

    We render a panoramic overview on copper (Cu) doped borate dosimeters. Preparing a dosimeter by mixing specific materials with precise weights and methods is a never-ending quest. The recommended composition is highly decisive for accurate estimation of the absorbed dose, prediction of the biological outcome, determination of the treatment dose for radiation therapy and facilitation of personal monitoring. Based on these principles, the proposed dosimeter must cover a series of dosimetric properties to realize the exact results and assessment. The doped borate dosimeters indeed demonstrate attractive thermoluminescence (TL) features. Several dedicated efforts are attempted to improve the luminescence properties by doping various transition metals or rare-earth elements. The Cu ion being one of the preferred activators shows excellent TL properties as revealed via detail comparison with other dosimeters. Two oxide states of Cu (Cu + and Cu ++ ) with reasonable atomic number allow easy interaction with boron network. Interestingly, the intrinsic luminescent centers of borate lattice are in cross linked with that of Cu + ions. Thus, the activation of borate dosimeter with Cu ions for the enhancement of the TL sensitivity is recognized. These dosimeters reveal similar glow curves as the standard TLD-100 (LiF:Mg,Ti) one irrespective of the use of modifiers and synthesis techniques. They display high sensitivity, low fading, dose response linearity over wide range and practical minimum detectable dose. Furthermore, the effective atomic number being the most beneficial aspect (equivalent to that of human tissue) of borate dosimeters do not show any change due to Cu ion activations. The past development, major challenges, excitement, applications, recent progress and the future promises of Cu doped borate TL dosimeters are highlighted. - Highlights: • The manuscript gives a panoramic overview on copper doped borate dosimeters. • Cu ions activated technique in borate

  6. 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.

  7. 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, ...

  8. Atom spectroscopy

    International Nuclear Information System (INIS)

    Kodling, K.

    1981-01-01

    Experiments on atom photoabsorption spectroscopy using synchrotron radiation in the 10-1000 eV range are reviewed. Properties of the necessary synchrotron radiation and the experiment on absorption spectroscopy are briefly described. Comparison with other spectroscopy methods is conducted. Some data on measuring photoabsorption, photoelectron emission and atom mass spectra are presented [ru

  9. Exotic atoms

    International Nuclear Information System (INIS)

    Horvath, D.; Lambrecht, R.M.

    1984-01-01

    This bibliography on exotic atoms covers the years 1939 till 1982. The annual entries are headed by an introduction describing the state of affairs of the branch of science and listing the main applications in quantum electrodynamics, particle physics, nuclear physics, atomic physics, chemical physics and biological sciences. The bibliography includes an author index and a subject index. (Auth.)

  10. Forensic seismology revisited

    Science.gov (United States)

    Douglas, A.

    2007-01-01

    The first technical discussions, held in 1958, on methods of verifying compliance with a treaty banning nuclear explosions, concluded that a monitoring system could be set up to detect and identify such explosions anywhere except underground: the difficulty with underground explosions was that there would be some earthquakes that could not be distinguished from an explosion. The development of adequate ways of discriminating between earthquakes and underground explosions proved to be difficult so that only in 1996 was a Comprehensive Nuclear Test Ban Treaty (CTBT) finally negotiated. Some of the important improvements in the detection and identification of underground tests—that is in forensic seismology—have been made by the UK through a research group at the Atomic Weapons Establishment (AWE). The paper describes some of the advances made in identification since 1958, particularly by the AWE Group, and the main features of the International Monitoring System (IMS), being set up to verify the Test Ban. Once the Treaty enters into force, then should a suspicious disturbance be detected the State under suspicion of testing will have to demonstrate that the disturbance was not a test. If this cannot be done satisfactorily the Treaty has provisions for on-site inspections (OSIs): for a suspicious seismic disturbance for example, an international team of inspectors will search the area around the estimated epicentre of the disturbance for evidence that a nuclear test really took place. Early observations made at epicentral distances out to 2,000 km from the Nevada Test Site showed that there is little to distinguish explosion seismograms from those of nearby earthquakes: for both source types the short-period (SP: ˜1 Hz) seismograms are complex showing multiple arrivals. At long range, say 3,000 10,000 km, loosely called teleseismic distances, the AWE Group noted that SP P waves—the most widely and well-recorded waves from underground explosions—were in

  11. Small-angle scattering theory revisited: Photocurrent and spatial localization

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Michelsen, Poul

    2005-01-01

    In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto......- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize quantities from two...

  12. Average Revisited in Context

    Science.gov (United States)

    Watson, Jane; Chick, Helen

    2012-01-01

    This paper analyses the responses of 247 middle school students to items requiring the concept of average in three different contexts: a city's weather reported in maximum daily temperature, the number of children in a family, and the price of houses. The mixed but overall disappointing performance on the six items in the three contexts indicates…

  13. Cancer stem cells revisited

    NARCIS (Netherlands)

    Batlle, Eduard; Clevers, Hans

    2017-01-01

    The cancer stem cell (CSC) concept was proposed four decades ago, and states that tumor growth, analogous to the renewal of healthy tissues, is fueled by small numbers of dedicated stem cells. It has gradually become clear that many tumors harbor CSCs in dedicated niches, and yet their

  14. Atomic fusion, Gerrard atomic fusion

    International Nuclear Information System (INIS)

    Gerrard, T.H.

    1980-01-01

    In the approach to atomic fusion described here the heat produced in a fusion reaction, which is induced in a chamber by the interaction of laser beams and U.H.F. electromagnetic beams with atom streams, is transferred to a heat exchanger for electricity generation by a coolant flowing through a jacket surrounding the chamber. (U.K.)

  15. Schroedinger's variational method of quantization revisited

    International Nuclear Information System (INIS)

    Yasue, K.

    1980-01-01

    Schroedinger's original quantization procedure is revisited in the light of Nelson's stochastic framework of quantum mechanics. It is clarified why Schroedinger's proposal of a variational problem led us to a true description of quantum mechanics. (orig.)

  16. 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.

  17. Enteroendocrine cell types revisited

    DEFF Research Database (Denmark)

    Engelstoft, Maja S; Egerod, Kristoffer Lihme; Lund, Mari L

    2013-01-01

    The GI-tract is profoundly involved in the control of metabolism through peptide hormones secreted from enteroendocrine cells scattered throughout the gut mucosa. A large number of recently generated transgenic reporter mice have allowed for direct characterization of biochemical and cell...... biological properties of these previously highly elusive enteroendocrine cells. In particular the surprisingly broad co-expression of six functionally related hormones in the intestinal enteroendocrine cells indicates that it should be possible to control not only the hormone secretion but also the type...... and number of enteroendocrine cells. However, this will require a more deep understanding of the factors controlling differentiation, gene expression and specification of the enteroendocrine cells during their weekly renewal from progenitor cells in the crypts of the mucosa....

  18. 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...

  19. 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.)

  20. Tourists' perceptions and intention to revisit Norway

    OpenAIRE

    Lazar, Ana Florina; Komolikova-Blindheim, Galyna

    2016-01-01

    Purpose - The overall purpose of this study is to explore tourists' perceptions and their intention to revisit Norway. The aim is to find out what are the factors that drive the overall satisfaction, the willingness to recommend and the revisit intention of international tourists that spend their holiday in Norway. Design-Method-Approach - the Theory of Planned Behavior (Ajzen 1991), is used as a framework to investigate tourists' intention and behavior towards Norway as destination. The o...

  1. Evolution Properties of Atomic Fidelity in the Combined Multi-Atom-Cavity Field System

    International Nuclear Information System (INIS)

    Wang Ju-Xia; Zhang Xiao-Juan; Zhang Xiu-Xing

    2015-01-01

    The atom fidelity is investigated in a system consisting of Mtwo-level atoms and M single-mode fields by use of complete quantum theory and numerical evaluation method. The influences of various system parameters on the evolution of atomic fidelity are studied. The results show that the atomic fidelity evolves in a Rabi oscillation manner. The oscillation frequency is mainly modulated by the coupling strength between atoms and light field, the atomic transition probabilities and the average photon numbers. Other factors hardly impact on the atomic fidelity. The present results may provide a useful approach to the maintenance of the atomic fidelity in the atom cavity field systems. (paper)

  2. The sunspot cycle revisited

    International Nuclear Information System (INIS)

    Lomb, Nick

    2013-01-01

    The set of sunspot numbers observed since the invention of the telescope is one of the most studied time series in astronomy and yet it is also one of the most complex. Fourteen frequencies are found in the yearly mean sunspot numbers from 1700 to 2011using the Lomb-Scargle periodogram and prewhitening. All of the frequencies corresponding to shorter term periods can be matched with simple algebraic combinations of the frequency of the main 11-year period and the frequencies of the longer term periods in the periodogram. This is exactly what can be expected from amplitude and phase modulation of an 11.12-year periodicity by longer term variations. Similar, though not identical, results are obtained after correcting the sunspot number series as proposed by Svalgaard. On looking separately at the amplitude and phase modulation a clear relationship is found between the two modulations although this relationship has broken down for the last four solar cycles. The phase modulation implies that there is a definite underlying period for the solar cycle. Such a clock mechanism does seem to be a possibility in models of the solar dynamo incorporating a conveyor-belt-like meridional circulation between high polar latitudes and the equator.

  3. Revisiting the TALE repeat.

    Science.gov (United States)

    Deng, Dong; Yan, Chuangye; Wu, Jianping; Pan, Xiaojing; Yan, Nieng

    2014-04-01

    Transcription activator-like (TAL) effectors specifically bind to double stranded (ds) DNA through a central domain of tandem repeats. Each TAL effector (TALE) repeat comprises 33-35 amino acids and recognizes one specific DNA base through a highly variable residue at a fixed position in the repeat. Structural studies have revealed the molecular basis of DNA recognition by TALE repeats. Examination of the overall structure reveals that the basic building block of TALE protein, namely a helical hairpin, is one-helix shifted from the previously defined TALE motif. Here we wish to suggest a structure-based re-demarcation of the TALE repeat which starts with the residues that bind to the DNA backbone phosphate and concludes with the base-recognition hyper-variable residue. This new numbering system is consistent with the α-solenoid superfamily to which TALE belongs, and reflects the structural integrity of TAL effectors. In addition, it confers integral number of TALE repeats that matches the number of bound DNA bases. We then present fifteen crystal structures of engineered dHax3 variants in complex with target DNA molecules, which elucidate the structural basis for the recognition of bases adenine (A) and guanine (G) by reported or uncharacterized TALE codes. Finally, we analyzed the sequence-structure correlation of the amino acid residues within a TALE repeat. The structural analyses reported here may advance the mechanistic understanding of TALE proteins and facilitate the design of TALEN with improved affinity and specificity.

  4. Rotating positron tomographs revisited

    International Nuclear Information System (INIS)

    Townsend, D.; Defrise, M.; Geissbuhler, A.

    1994-01-01

    We have compared the performance of a PET scanner comprising two rotating arrays of detectors with that of the more conventional stationary-ring design. The same total number of detectors was used in each, and neither scanner had septa. For brain imaging, we find that the noise-equivalent count rate is greater for the rotating arrays by a factor of two. Rotating arrays have a sensitivity profile that peaks in the centre of the field of view, both axially and transaxially. In the transaxial plane, this effect offsets to a certain extent the decrease in the number of photons detected towards the centre of the brain due to self-absorption. We have also compared the performance of a rotating scanner to that of a full-ring scanner with the same number of rings. We find that a full-ring scanner with an axial extent of 16.2 cm (24 rings) is a factor of 3.5 more sensitive than a rotating scanner with 40% of the detectors and the same axial extent. (Author)

  5. Effect of dietary fats with odd or even numbers of carbon atoms on metabolic response and muscle damage with exercise in Quarter Horse-type horses with type 1 polysaccharide storage myopathy.

    Science.gov (United States)

    Borgia, Lisa A; Valberg, Stephanie J; McCue, Molly E; Pagan, Joe D; Roe, Charles R

    2010-03-01

    To evaluate effects of fats with odd and even numbers of carbon atoms on muscle metabolism in exercising horses with polysaccharide storage myopathy (PSSM). 8 horses with PSSM (6 females and 2 males; mean +/- SD age, 6.3 +/- 3.9 years). Isocaloric diets (grain, triheptanoin, corn oil, and high-fat, low-starch [HFLS] feed) were fed for 3 weeks each; horses performed daily treadmill exercise. Grain was fed to establish an exercise target, and HFLS feed was fed as a negative control diet. Daily plasma samples were obtained. For each diet, a 15-minute exercise test was performed, and gluteus medius muscle specimens and blood samples were obtained before and after exercise. Feeding triheptanoin, compared with the corn oil diet, resulted in exercise intolerance; higher plasma creatine kinase (CK) activity and concentrations of C3:0- and C7:0-acylcarnitine and insulin; and lower concentrations of nonesterified fatty acids (NEFA) and C16:0-, C18:1-, and C18:2-acylcarnitine, without changes in concentrations of plasma glucose or resting muscle substrates and metabolites. Feeding grain induced higher CK activity and insulin concentrations and lower NEFA concentrations than did corn oil or HFLS feed. Feeding grain induced higher glucose concentrations than did triheptanoin and corn oil. In muscle, feeding grain resulted in lower glucose-6-phosphate, higher citrate, and higher postexercise lactate concentrations than did the other diets. Triheptanoin had detrimental effects, reflecting decreased availability of NEFA, increased insulin stimulation of glycogen synthesis, and potential inhibition of lipid oxidation. Long-chain fats are the best dietetic for PSSM.

  6. Atomic interferometry

    International Nuclear Information System (INIS)

    Baudon, J.; Robert, J.

    2004-01-01

    Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation λ = h/(mv), where λ is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

  7. Asymmetric Gepner models (revisited)

    Energy Technology Data Exchange (ETDEWEB)

    Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain)] [IMAPP, Radboud Universiteit, Nijmegen (Netherlands)

    2010-12-11

    We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N=2 minimal models with asymmetric simple current invariants. We extend this analysis from (2,2) and (1,2) spectra to (0,2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N=2 tensor products. We observe that distributions of physical quantities such as the number of families, singlets and mirrors have an interesting tendency towards smaller values as the gauge groups approaches the Standard Model. We compare our results with an analogous class of free fermionic models. This displays similar features, but with less resolution. Finally we present a complete scan of the three family models based on the triply-exceptional combination (1,16{sup *},16{sup *},16{sup *}) identified originally by Gepner. We find 1220 distinct three family spectra in this case, forming 610 mirror pairs. About half of them have the gauge group SU(3)xSU(2){sub L}xSU(2){sub R}xU(1){sup 5}, the theoretical minimum, and many others are trinification models.

  8. 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.)

  9. Audit culture revisited

    DEFF Research Database (Denmark)

    Shore, Cris; Wright, Susan

    2015-01-01

    the financial and the moral meet’ we ask, what new kinds of ‘ethics of accountability’ does audit produce? We build on the work of Mitchell (1999), Trouillot (2001) and Merry (2011) to identify five ways in which the techniques and logics of financial accountancy have notable ‘audit effects...... these new financialized techniques of governance, not least through the work of the ‘Big 4’ accountancy firms, and trace their impact across a number of different fields, from administration and the military to business corporations and universities. Following Strathern’s observation that audit is ‘where...

  10. BeII** revisited

    International Nuclear Information System (INIS)

    Fischer, C.F.

    1982-01-01

    Doubly excited 1s2snl and 1s2pnl quartet states of BeII** are readily populated in beam-foil experiments and line-rich spectra have been obtained covering 600 to 5500 A wavelength range. In spite of several theoretical calculations a substantial number of observed lines have not been identified. The quartet system in BeII is an intersting one from a theoretical point of view. Three electron systems are simple enough that a fairly high level of accuracy is attainable without the calculations becoming horrendous. The important correlation effects are between the outer two electrons and, to a good approximation, the three-electrons system may be treated as a two-electron system outside a 1s-core. The multi-configuration Hartree-Fock (MCHF) method has been used successfully in a number of studies. Programs are under development that take into account the non-orthogonality of orbitals in the initial and final state, and allow for some non-orthogonal orbitals in a wavefunction expansion. LS dependent relativistic effects are also included. A study of BeII** was undertaken to evaluate the MCHF techniques being developed and to assit in the identification of observed lines. Most of the earlier calculations concentrated on the lower-lying levels. In this work particular attention was given to the more highly-excited states, though calculations for lower-lying states had to be repeated in order to predict life-times

  11. Meta-analysis in clinical trials revisited.

    Science.gov (United States)

    DerSimonian, Rebecca; Laird, Nan

    2015-11-01

    In this paper, we revisit a 1986 article we published in this Journal, Meta-Analysis in Clinical Trials, where we introduced a random-effects model to summarize the evidence about treatment efficacy from a number of related clinical trials. Because of its simplicity and ease of implementation, our approach has been widely used (with more than 12,000 citations to date) and the "DerSimonian and Laird method" is now often referred to as the 'standard approach' or a 'popular' method for meta-analysis in medical and clinical research. The method is especially useful for providing an overall effect estimate and for characterizing the heterogeneity of effects across a series of studies. Here, we review the background that led to the original 1986 article, briefly describe the random-effects approach for meta-analysis, explore its use in various settings and trends over time and recommend a refinement to the method using a robust variance estimator for testing overall effect. We conclude with a discussion of repurposing the method for Big Data meta-analysis and Genome Wide Association Studies for studying the importance of genetic variants in complex diseases. Published by Elsevier Inc.

  12. Critical boundary sine-Gordon revisited

    International Nuclear Information System (INIS)

    Hasselfield, M.; Lee, Taejin; Semenoff, G.W.; Stamp, P.C.E.

    2006-01-01

    We revisit the exact solution of the two space-time dimensional quantum field theory of a free massless boson with a periodic boundary interaction and self-dual period. We analyze the model by using a mapping to free fermions with a boundary mass term originally suggested in Ref. [J. Polchinski, L. Thorlacius, Phys. Rev. D 50 (1994) 622]. We find that the entire SL (2, C) family of boundary states of a single boson are boundary sine-Gordon states and we derive a simple explicit expression for the boundary state in fermion variables and as a function of sine-Gordon coupling constants. We use this expression to compute the partition function. We observe that the solution of the model has a strong-weak coupling generalization of T-duality. We then examine a class of recently discovered conformal boundary states for compact bosons with radii which are rational numbers times the self-dual radius. These have simple expression in fermion variables. We postulate sine-Gordon-like field theories with discrete gauge symmetries for which they are the appropriate boundary states

  13. Cavity electromagnetically induced transparency with Rydberg atoms

    Science.gov (United States)

    Bakar Ali, Abu; Ziauddin

    2018-02-01

    Cavity electromagnetically induced transparency (EIT) is revisited via the input probe field intensity. A strongly interacting Rydberg atomic medium ensemble is considered in a cavity, where atoms behave as superatoms (SAs) under the dipole blockade mechanism. Each atom in the strongly interacting Rydberg atomic medium (87 Rb) follows a three-level cascade atomic configuration. A strong control and weak probe field are employed in the cavity with the ensemble of Rydberg atoms. The features of the reflected and transmitted probe light are studied under the influence of the input probe field intensity. A transparency peak (cavity EIT) is revealed at a resonance condition for small values of input probe field intensity. The manipulation of the cavity EIT is reported by tuning the strength of the input probe field intensity. Further, the phase and group delay of the transmitted and reflected probe light are studied. It is found that group delay and phase in the reflected light are negative, while for the transmitted light they are positive. The magnitude control of group delay in the transmitted and reflected light is investigated via the input probe field intensity.

  14. 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)

  15. Serum prolactin revisited

    DEFF Research Database (Denmark)

    Overgaard, Martin; Pedersen, Susanne Møller

    2017-01-01

    regimes across commonly used automated immunoassay platforms. METHODS: Parametric total and monomeric gender-specific reference intervals were determined for six immunoassay methods using female (n=96) and male sera (n=127) from healthy donors. The reference intervals were validated using 27...... and macroprolactinemic; n=27) showed higher discordant classification [mean=2.8; 95% confidence interval (CI) 1.2-4.4] for the monomer reference interval method compared to the post-polyethylene glycol (PEG) recovery cutoff method (mean=1.8; 95% CI 0.8-2.8). The two monomer/macroprolactin discrimination methods did...... not differ significantly (p=0.089). Among macroprolactinemic sera evaluated by both discrimination methods, the Cobas and Architect/Kryptor prolactin assays showed the lowest and the highest number of misclassifications, respectively. CONCLUSIONS: Current automated immunoassays for prolactin testing require...

  16. Intrauterine Insemination: Fundamentals Revisited.

    Science.gov (United States)

    Allahbadia, Gautam N

    2017-12-01

    Intrauterine insemination (IUI) is an assisted conception technique that involves the deposition of a processed semen sample in the upper uterine cavity, overcoming natural barriers to sperm ascent in the female reproductive tract. It is a cost-effective, noninvasive first-line therapy for selected patients with functionally normal tubes, and infertility due to a cervical factor, anovulation, moderate male factor, unexplained factors, immunological factor, and ejaculatory disorders with clinical pregnancy rates per cycle ranging from 10 to 20%. It, however, has limited use in patients with endometriosis, severe male factor infertility, tubal factor infertility, and advanced maternal age ≥ 35 years. IUI may be performed with or without ovarian stimulation. Controlled ovarian stimulation, particularly with low-dose gonadotropins, with IUI offers significant benefit in terms of pregnancy outcomes compared with natural cycle or timed intercourse, while reducing associated COH complications such as multiple pregnancies and ovarian hyperstimulation syndrome. Important prognostic indicators of success with IUI include age of patient, duration of infertility, stimulation protocol, infertility etiology, number of cycles, timing of insemination, number of preovulatory follicles on the day of hCG, processed total motile sperm > 10 million, and insemination count > 1 × 106 with > 4% normal spermatozoa. Alternative insemination techniques, such as Fallopian tube sperm perfusion, intracervical insemination, and intratubal insemination, provide no additional benefit compared to IUI. A complete couple workup that includes patient history, physical examination, and clinical and laboratory investigations is mandatory to justify the choice in favor of IUI and guide alternative patient management, while individualizing the treatment protocol according to the patient characteristics with a strict cancelation policy to limit multi-follicular development may help optimize IUI

  17. Stanford polarized atomic beam target

    International Nuclear Information System (INIS)

    Mavis, D.G.; Dunham, J.S.; Hugg, J.W.; Glavish, H.F.

    1976-01-01

    A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used as a polarized proton target. A target density of 2 x 10'' atoms/cm 3 and a target polarization of 0.37 without the use of rf transitions were measured. These measurements indicate that a number of experiments are currently feasible with a variety of polarized target beams

  18. 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)

  19. Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited

    DEFF Research Database (Denmark)

    Miao, L.; Lomholt, Michael Andersen; Kleis, J.

    2002-01-01

    In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy......In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations...... of the phenomenological constants in a canonical continuum description of fluid lipid-bilayer membranes and shown the consequences of this new interpretation in terms of the characteristics of the dynamics of vesicle shape fluctuations. Moreover, we have used the systematic formulation of our theory as a framework...... against which we have discussed the previously existing theories and their discrepancies. Finally, we have made a systematic prediction about the system-dependent characteristics of the relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a view of experimental studies...

  20. Atomic secrecy

    International Nuclear Information System (INIS)

    Sweet, W.

    1979-01-01

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  1. 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.

  2. Atom chip gravimeter

    Science.gov (United States)

    Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

    2016-04-01

    Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM

  3. Orthovoltage machines revisited

    International Nuclear Information System (INIS)

    Piyaratna, N.; Ariyaratna, K.

    2000-01-01

    Until the advent of megavoltage radiation, orthovoltage units operating up to 300 KV were used to deliver radiotherapy. Side effects due to higher doses to normal organs were inevitable because of less penetrating photon beams. With the advent of the megavoltage equipment more penetrating photon beams replaced the orthovoltage beams to treat deep seated tumours more effectively. The use of the orthovoltage energy range has since been limited to superficial skin cancers and many palliative treatments such as bony metastases, in particular ribs and spine. When the Linear Accelerators (linacs) with electron energy range were introduced into the radiotherapy field the use of orthovoltage range was further reduced. The electron beams were successfully used to treat superficial cancers and the demand for the orthovoltage units became less. Because of this many of the reputable manufacturers of orthovoltage units (eg. Philips) ceased the production of these units over a decade. During the eighties, the only available orthovoltage unit was the Siemens Stabilopan. In the early nineties Pantak introduced a new orthovoltage unit incorporated with new technology. NSW cancer treatment centres purchased several of these machines. Considering the capital cost and the annual maintenance cost, reliability, computer controlled accurate dose delivery, number of RT staff required to operate the unit and the Medicare revenue, it is cost beneficial to install an orthovoltage unit in a modern radiotherapy department. Copyright (1999) Australian Institute of Radiography

  4. Photonic Molecule Lasers Revisited

    Science.gov (United States)

    Gagnon, Denis; Dumont, Joey; Déziel, Jean-Luc; Dubé, Louis J.

    2014-05-01

    Photonic molecules (PMs) formed by coupling two or more optical resonators are ideal candidates for the fabrication of integrated microlasers, photonic molecule lasers. Whereas most calculations on PM lasers have been based on cold-cavity (passive) modes, i.e. quasi-bound states, a recently formulated steady-state ab initio laser theory (SALT) offers the possibility to take into account the spectral properties of the underlying gain transition, its position and linewidth, as well as incorporating an arbitrary pump profile. We will combine two theoretical approaches to characterize the lasing properties of PM lasers: for two-dimensional systems, the generalized Lorenz-Mie theory will obtain the resonant modes of the coupled molecules in an active medium described by SALT. Not only is then the theoretical description more complete, the use of an active medium provides additional parameters to control, engineer and harness the lasing properties of PM lasers for ultra-low threshold and directional single-mode emission. We will extend our recent study and present new results for a number of promising geometries. The authors acknowledge financial support from NSERC (Canada) and the CERC in Photonic Innovations of Y. Messaddeq.

  5. Dutch euthanasia revisited.

    Science.gov (United States)

    Fenigsen, R

    1997-01-01

    The results of a follow-up study of euthanasia by the Dutch government, five years after the first study, were published on November 26, 1996. This article provides a detailed review of the two reports comparing and contrasting the statistics cited therein. The author notes that the "rules of careful conduct" proposed by the courts and by the Royal Dutch Society of Medicine were frequently disregarded. Special topics included for the first time in the second study were the notification and non-prosecution procedure, euthanasia of newborns and infants, and assisted suicide in psychiatric practice. The authors of the follow-up report state that it would be desirable to reduce the number of "terminations of life without patients' request," but this must be the common responsibility of the doctor and the patient. They suggest that the person who does not wish to have his life terminated should declare this clearly, in advance, verbally and in writing, preferably in the form of a living will. Involuntary euthanasia was rampant in 1990 and equally rampant in 1995. The author concludes that Dutch doctors who practice euthanasia are not on the slippery slope. From the very beginning, they have been at the bottom.

  6. Cube search, revisited

    Science.gov (United States)

    Zhang, Xuetao; Huang, Jie; Yigit-Elliott, Serap; Rosenholtz, Ruth

    2015-01-01

    Observers can quickly search among shaded cubes for one lit from a unique direction. However, replace the cubes with similar 2-D patterns that do not appear to have a 3-D shape, and search difficulty increases. These results have challenged models of visual search and attention. We demonstrate that cube search displays differ from those with “equivalent” 2-D search items in terms of the informativeness of fairly low-level image statistics. This informativeness predicts peripheral discriminability of target-present from target-absent patches, which in turn predicts visual search performance, across a wide range of conditions. Comparing model performance on a number of classic search tasks, cube search does not appear unexpectedly easy. Easy cube search, per se, does not provide evidence for preattentive computation of 3-D scene properties. However, search asymmetries derived from rotating and/or flipping the cube search displays cannot be explained by the information in our current set of image statistics. This may merely suggest a need to modify the model's set of 2-D image statistics. Alternatively, it may be difficult cube search that provides evidence for preattentive computation of 3-D scene properties. By attributing 2-D luminance variations to a shaded 3-D shape, 3-D scene understanding may slow search for 2-D features of the target. PMID:25780063

  7. Recombination epoch revisited

    International Nuclear Information System (INIS)

    Krolik, J.H.

    1989-01-01

    Previous studies of cosmological recombination have shown that this process produces as a by-product a highly superthermal population of Ly-alpha photons which retard completion of recombination. Cosmological redshifting was thought to determine the frequency distribution of the photons, while two-photon decay of hydrogen's 2s state was thought to control their numbers. It is shown here that frequency diffusion due to photon scattering dominate the cosmological redshift in the frequency range near line center which fixes the ratio of ground state to excited state population, while incoherent scattering into the far-red damping wing effectively destroys Ly-alpha photons as a rate which is competitive with two-photon decay. The former effect tends to hold back recombination, while the latter tends to accelerate it; the net results depends on cosmological parameters, particularly the combination Omega(b) h/sq rt (2q0), where Omega(b) is the fraction of the critical density provided by baryons. 18 references

  8. The Levy sections theorem revisited

    International Nuclear Information System (INIS)

    Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Silva, Sergio Da

    2007-01-01

    This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets

  9. The power reinforcement framework revisited

    DEFF Research Database (Denmark)

    Nielsen, Jeppe; Andersen, Kim Normann; Danziger, James N.

    2016-01-01

    Whereas digital technologies are often depicted as being capable of disrupting long-standing power structures and facilitating new governance mechanisms, the power reinforcement framework suggests that information and communications technologies tend to strengthen existing power arrangements within...... public organizations. This article revisits the 30-yearold power reinforcement framework by means of an empirical analysis on the use of mobile technology in a large-scale programme in Danish public sector home care. It explores whether and to what extent administrative management has controlled decision......-making and gained most benefits from mobile technology use, relative to the effects of the technology on the street-level workers who deliver services. Current mobile technology-in-use might be less likely to be power reinforcing because it is far more decentralized and individualized than the mainly expert...

  10. The Levy sections theorem revisited

    Science.gov (United States)

    Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Da Silva, Sergio

    2007-06-01

    This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets.

  11. The Armstrong experiment revisited

    Science.gov (United States)

    Fuchs, Elmar C.; Wexler, Adam D.; Paulitsch-Fuchs, Astrid H.; Agostinho, Luewton L. F.; Yntema, Doekle; Woisetschläger, Jakob

    2014-04-01

    When a high-voltage direct-current is applied to two beakers filled with water or polar liquid dielectrica, a horizontal bridge forms between the two beakers. This experiment was first carried out by Lord Armstrong in 1893 and then forgotten until recently. Such bridges are stable by the action of electrohydrodynamic (EHD) forces caused by electric field gradients counteracting gravity. Due to these gradients a permanent pumping of liquid from one beaker into the other is observed. At macroscopic scale several of the properties of a horizontal water bridge can be explained by modern electrohydrodynamics, analyzing the motion of fluids in electric fields. Whereas on the molecular scale water can be described by quantum mechanics, there is a conceptual gap at mesoscopic scale which is bridged by a number of theories including quantum mechanical entanglement and coherent structures in water - theories that we discuss here. Much of the phenomenon is already understood, but even more can still be learned from it, since such "floating" liquid bridges resemble a small high voltage laboratory of their own: The physics of liquids in electric fields of some kV/cm can be studied, even long time experiments like neutron or light scattering are feasible since the bridge is in a steady-state equilibrium and can be kept stable for hours. It is also an electro-chemical reactor where compounds are transported through by the EHD flow, enabling the study of electrochemical reactions under potentials which are otherwise not easily accessible. Last but not least the bridge provides the experimental biologist with the opportunity to expose living organisms such as bacteria to electric fields without killing them, but with a significant influence on their behavior, and possibly, even on their genome.

  12. Hotspot swells revisited

    Science.gov (United States)

    King, Scott D.; Adam, Claudia

    2014-10-01

    The first attempts to quantify the width and height of hotspot swells were made more than 30 years ago. Since that time, topography, ocean-floor age, and sediment thickness datasets have improved considerably. Swell heights and widths have been used to estimate the heat flow from the core-mantle boundary, constrain numerical models of plumes, and as an indicator of the origin of hotspots. In this paper, we repeat the analysis of swell geometry and buoyancy flux for 54 hotspots, including the 37 considered by Sleep (1990) and the 49 considered by Courtillot et al. (2003), using the latest and most accurate data. We are able to calculate swell geometry for a number of hotspots that Sleep was only able to estimate by comparison with other swells. We find that in spite of the increased resolution in global bathymetry models there is significant uncertainty in our calculation of buoyancy fluxes due to differences in our measurement of the swells’ width and height, the integration method (volume integration or cross-sectional area), and the variations of the plate velocities between HS2-Nuvel1a (Gripp and Gordon, 1990) and HS3-Nuvel1a (Gripp and Gordon, 2002). We also note that the buoyancy flux for Pacific hotspots is in general larger than for Eurasian, North American, African and Antarctic hotspots. Considering that buoyancy flux is linearly related to plate velocity, we speculate that either the calculation of buoyancy flux using plate velocity over-estimates the actual vertical flow of material from the deep mantle or that convection in the Pacific hemisphere is more vigorous than the Atlantic hemisphere.

  13. Radiolytic graphite oxidation revisited

    International Nuclear Information System (INIS)

    Minshall, P.C.; Sadler, I.A.; Wickham, A.J.

    1996-01-01

    The importance of radiolytic oxidation in graphite-moderated CO 2 -cooled reactors has long been recognised, especially in the Advanced Gas-Cooled Reactors where potential rates are higher because of the higher gas pressure and ratings than the earlier Magnox designs. In all such reactors, the rate of oxidation is partly inhibited by the CO produced in the reaction and, in the AGR, further reduced by the deliberate addition of CH 4 . Significant roles are also played by H 2 and H 2 O. This paper reviews briefly the mechanisms of these processes and the data on which they are based. However, operational experience has demonstrated that these basic principles are unsatisfactory in a number of respects. Gilsocarbon graphites produced by different manufacturers have demonstrated a significant difference in oxidation rate despite a similar specification and apparent equivalence in their pore size and distribution, considered to be the dominant influence on oxidation rate for a given coolant-gas composition. Separately, the inhibiting influence of CH 4 , which for many years had been considered to arise from the formation of a sacrificial deposit on the pore walls, cannot adequately be explained by the actual quantities of such deposits found in monitoring samples which frequently contain far less deposited carbon than do samples from Magnox reactors where the only source of such deposits is the CO. The paper also describes the current status of moderator weight-loss predictions for Magnox and AGR Moderators and the validation of the POGO and DIFFUSE6 codes respectively. 2 refs, 5 figs

  14. Antimatter atoms

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    In january 1996, CERN broadcasted the information of the creation of nine anti-hydrogen atoms, observed through disintegration products. The experimental facility was CERN LEAR ring. An antiproton beam scattered a xenon jet, and the resulting antimatter was first selected by its insensitivity to beam bending magnets. Their disintegration was detected in thin NaI detectors, in which the anti-atoms are at once deprived from their positron. Then, magnetic and time-of-flight spectrometers are used. (D.L.)

  15. 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

  16. Energy efficiency fallacies revisited

    International Nuclear Information System (INIS)

    Brookes, Leonard

    2000-01-01

    A number of governments including that of the UK subscribe to the belief that a national program devoted to raising energy efficiency throughout the economy provides a costless - indeed profitable - route to meeting international environmental obligations. This is a seductive policy. It constitutes the proverbial free lunch - not only avoiding politically unpopular measures like outlawing, taxing or rationing offending fuels or expanding non-carboniferous sources of energy like nuclear power but doing so with economic benefit. The author of this contribution came to doubt the validity of this solution when it was offered as a way of mitigating the effect of the OPEC price hikes of the 1970s, maintaining that economically justified improvement in energy efficiency led to higher levels of energy consumption at the economy-wide level than in the absence of any efficiency response. More fundamentally, he argues that there is no case for preferentially singling out energy, from among all the resources available to us, for efficiency maximisation. The least damaging policy is to determine targets, enact the restrictive measures needed to curb consumption, and then leave it to consumers - intermediate and final - to reallocate all the resources available to them to best effect subject to the new enacted constraints and any others they might be experiencing. There is no reason to suppose that it is right for all the economic adjustment following a new resource constraint to take the form of improvements in the productivity of that resource alone. As many others have argued, any action to impose resource constraint entails an inevitable economic cost in the shape of a reduction in production and consumption possibilities: there would be no free lunch. In the last few years debate about the validity of these contentions has blossomed, especially under the influence of writers on the western side of the Atlantic. In this contribution the author outlines the original arguments

  17. Histamine fish poisoning revisited.

    Science.gov (United States)

    Lehane, L; Olley, J

    2000-06-30

    distribution system, or in restaurants or homes. The key to keeping bacterial numbers and histamine levels low is the rapid cooling of fish after catching and the maintenance of adequate refrigeration during handling and storage. Despite the huge expansion in trade in recent years, great progress has been made in ensuring the quality and safety of fish products. This is largely the result of the introduction of international standards of food hygiene and the application of risk analysis and hazard analysis and critical control point (HACCP) principles.

  18. Pulsed atomic soliton laser

    International Nuclear Information System (INIS)

    Carr, L.D.; Brand, J.

    2004-01-01

    It is shown that simultaneously changing the scattering length of an elongated, harmonically trapped Bose-Einstein condensate from positive to negative and inverting the axial portion of the trap, so that it becomes expulsive, results in a train of self-coherent solitonic pulses. Each pulse is itself a nondispersive attractive Bose-Einstein condensate that rapidly self-cools. The axial trap functions as a waveguide. The solitons can be made robustly stable with the right choice of trap geometry, number of atoms, and interaction strength. Theoretical and numerical evidence suggests that such a pulsed atomic soliton laser can be made in present experiments

  19. Sternal wound infection revisited

    International Nuclear Information System (INIS)

    Liberatore, M.; Fiore, V.; D'Agostini, A.; Prosperi, D.; Iurilli, A.P.; Santini, C.; Baiocchi, P.; Galie, M.; Di Nucci, G.D.; Sinatra, R.

    2000-01-01

    .7% and 70.6% and a negative predictive value of 77.3% and 100%. The scintigraphic results obtained in superficial SWI yielded a sensitivity of 56.2%, a specificity of 90.9%, an accuracy of 76.3%, a positive predictive value of 81.8% and a negative predictive value of 74.1%, while, by contrast, in deep SWI all of these values were 100%. Therefore, one can conclude that 99m Tc-HMPAO labelled leucocyte scan permits accurate diagnosis of deep SWI, solving the main clinical problem in this field. In the present study the categorisation of patients without taking into account 99m Tc-HMPAO labelled leucocyte planar scan findings caused a non-negligible number of cases of superficial SWI to be treated as though they were deep SWI. This ''overestimation'' led to unnecessary surgery, increased and prolonged use of antibiotics with more (higher) toxicity and additional expense. (orig.)

  20. Atoms stories

    International Nuclear Information System (INIS)

    Radvanyi, P.; Bordry, M.

    1988-01-01

    Physicists from different countries told each evening during one learning week, to an audience of young people, some great discoveries in evoking the difficulties and problems to which the researchers were confronted. From Antiquity to a more recent history, it is a succession of atoms stories. (N.C.)

  1. 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

  2. Quantum information with Rydberg atoms

    DEFF Research Database (Denmark)

    Saffman, Mark; Walker, T.G.; Mølmer, Klaus

    2010-01-01

    Rydberg atoms with principal quantum number n»1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom...... of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing....

  3. Revisiting tourist behavior via destination brand worldness

    Directory of Open Access Journals (Sweden)

    Murat Kayak

    2016-11-01

    Full Text Available Taking tourists’ perspective rather than destination offerings as its core concept, this study introduces “perceived destination brand worldness” as a variable. Perceived destination brand worldness is defined as the positive perception that a tourist has of a country that is visited by tourists from all over the world. Then, the relationship between perceived destination brand worldness and intention to revisit is analyzed using partial least squares regression. This empirical study selects Taiwanese tourists as its sample, and the results show that perceived destination brand worldness is a direct predictor of intention to revisit. In light of these empirical findings and observations, practical and theoretical implications are discussed.

  4. Double neutron stars: merger rates revisited

    Science.gov (United States)

    Chruslinska, Martyna; Belczynski, Krzysztof; Klencki, Jakub; Benacquista, Matthew

    2018-03-01

    We revisit double neutron star (DNS) formation in the classical binary evolution scenario in light of the recent Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo DNS detection (GW170817). The observationally estimated Galactic DNS merger rate of R_MW = 21^{+28}_{-14} Myr-1, based on three Galactic DNS systems, fully supports our standard input physics model with RMW = 24 Myr-1. This estimate for the Galaxy translates in a non-trivial way (due to cosmological evolution of progenitor stars in chemically evolving Universe) into a local (z ≈ 0) DNS merger rate density of Rlocal = 48 Gpc-3 yr-1, which is not consistent with the current LIGO/Virgo DNS merger rate estimate (1540^{+3200}_{-1220} Gpc-3 yr-1). Within our study of the parameter space, we find solutions that allow for DNS merger rates as high as R_local ≈ 600^{+600}_{-300} Gpc-3 yr-1 which are thus consistent with the LIGO/Virgo estimate. However, our corresponding BH-BH merger rates for the models with high DNS merger rates exceed the current LIGO/Virgo estimate of local BH-BH merger rate (12-213 Gpc-3 yr-1). Apart from being particularly sensitive to the common envelope treatment, DNS merger rates are rather robust against variations of several of the key factors probed in our study (e.g. mass transfer, angular momentum loss, and natal kicks). This might suggest that either common envelope development/survival works differently for DNS (˜10-20 M⊙ stars) than for BH-BH (˜40-100 M⊙ stars) progenitors, or high black hole (BH) natal kicks are needed to meet observational constraints for both types of binaries. Our conclusion is based on a limited number of (21) evolutionary models and is valid within this particular DNS and BH-BH isolated binary formation scenario.

  5. 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)

  6. Individualist Biocentrism vs. Holism Revisited

    Directory of Open Access Journals (Sweden)

    Katie McShane

    2014-06-01

    Full Text Available While holist views such as ecocentrism have considerable intuitive appeal, arguing for the moral considerability of ecological wholes such as ecosystems has turned out to be a very difficult task. In the environmental ethics literature, individualist biocentrists have persuasively argued that individual organisms—but not ecological wholes—are properly regarded as having a good of their own . In this paper, I revisit those arguments and contend that they are fatally flawed. The paper proceeds in five parts. First, I consider some problems brought about by climate change for environmental conservation strategies and argue that these problems give us good pragmatic reasons to want a better account of the welfare of ecological wholes. Second, I describe the theoretical assumptions from normative ethics that form the background of the arguments against holism. Third, I review the arguments given by individualist biocentrists in favour of individualism over holism. Fourth, I review recent work in the philosophy of biology on the units of selection problem, work in medicine on the human biome, and work in evolutionary biology on epigenetics and endogenous viral elements. I show how these developments undermine both the individualist arguments described above as well as the distinction between individuals and wholes as it has been understood by individualists. Finally, I consider five possible theoretical responses to these problems.

  7. Revisiting the safety of aspartame.

    Science.gov (United States)

    Choudhary, Arbind Kumar; Pretorius, Etheresia

    2017-09-01

    Aspartame is a synthetic dipeptide artificial sweetener, frequently used in foods, medications, and beverages, notably carbonated and powdered soft drinks. Since 1981, when aspartame was first approved by the US Food and Drug Administration, researchers have debated both its recommended safe dosage (40 mg/kg/d) and its general safety to organ systems. This review examines papers published between 2000 and 2016 on both the safe dosage and higher-than-recommended dosages and presents a concise synthesis of current trends. Data on the safe aspartame dosage are controversial, and the literature suggests there are potential side effects associated with aspartame consumption. Since aspartame consumption is on the rise, the safety of this sweetener should be revisited. Most of the literature available on the safety of aspartame is included in this review. Safety studies are based primarily on animal models, as data from human studies are limited. The existing animal studies and the limited human studies suggest that aspartame and its metabolites, whether consumed in quantities significantly higher than the recommended safe dosage or within recommended safe levels, may disrupt the oxidant/antioxidant balance, induce oxidative stress, and damage cell membrane integrity, potentially affecting a variety of cells and tissues and causing a deregulation of cellular function, ultimately leading to systemic inflammation. © The Author(s) 2017. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. Gauss Sum Factorization with Cold Atoms

    International Nuclear Information System (INIS)

    Gilowski, M.; Wendrich, T.; Mueller, T.; Ertmer, W.; Rasel, E. M.; Jentsch, Ch.; Schleich, W. P.

    2008-01-01

    We report the first implementation of a Gauss sum factorization algorithm by an internal state Ramsey interferometer using cold atoms. A sequence of appropriately designed light pulses interacts with an ensemble of cold rubidium atoms. The final population in the involved atomic levels determines a Gauss sum. With this technique we factor the number N=263193

  9. Exotic atoms

    International Nuclear Information System (INIS)

    Kunselman, R.

    1993-01-01

    The experiments use a solid hydrogen layer to form muonic hydrogen isotopes that escape into vacuum. The method relies on transfer of the muon from protium to either a deuteron or a triton. The resulting muonic deuterium or muonic tritium will not immediately thermalize because of the very low elastic cross sections, and may be emitted from the surface of the layer. Measurements which detect decay electrons, muonic x-rays, and fusion products have been used to study the processes. A target has been constructed which exploits muonic atom emission in order to learn more about the energy dependence of transfer and muon molecular formation

  10. Hupa Numbers.

    Science.gov (United States)

    Bennett, Ruth, Ed.; And Others

    An introduction to the Hupa number system is provided in this workbook, one in a series of numerous materials developed to promote the use of the Hupa language. The book is written in English with Hupa terms used only for the names of numbers. The opening pages present the numbers from 1-10, giving the numeral, the Hupa word, the English word, and…

  11. Triangular Numbers

    Indian Academy of Sciences (India)

    Admin

    Triangular number, figurate num- ber, rangoli, Brahmagupta–Pell equation, Jacobi triple product identity. Figure 1. The first four triangular numbers. Left: Anuradha S Garge completed her PhD from. Pune University in 2008 under the supervision of Prof. S A Katre. Her research interests include K-theory and number theory.

  12. Proth Numbers

    Directory of Open Access Journals (Sweden)

    Schwarzweller Christoph

    2015-02-01

    Full Text Available In this article we introduce Proth numbers and prove two theorems on such numbers being prime [3]. We also give revised versions of Pocklington’s theorem and of the Legendre symbol. Finally, we prove Pepin’s theorem and that the fifth Fermat number is not prime.

  13. Curious behavior of optically trapped neutral atoms

    International Nuclear Information System (INIS)

    Wieman, C.; Walker, T.; Sesko, D.; Monroe, C.

    1991-01-01

    We have studied the behavior of clouds of neutral atoms contained in a spontaneous force optical trap. Because of the low temperatures of the atoms ( 5 atoms. These include the expansion of the cloud as the number is increased and dramatic changes in the distribution of the atoms at higher numbers. We can explain much of the collective behavior using a simple model that includes a 1/r 2 force between the atoms arising from the multiple scattering of photons. Finally, we discuss the optical trapping of atoms directly from a low pressure vapor in a small glass cell. We have used these optically trapped atoms to load a magnetostatic trap in the same cell. This provided a high density sample of atoms with a temperature of less than 2 μK

  14. Sagan numbers

    OpenAIRE

    Mendonça, J. Ricardo G.

    2012-01-01

    We define a new class of numbers based on the first occurrence of certain patterns of zeros and ones in the expansion of irracional numbers in a given basis and call them Sagan numbers, since they were first mentioned, in a special case, by the North-american astronomer Carl E. Sagan in his science-fiction novel "Contact." Sagan numbers hold connections with a wealth of mathematical ideas. We describe some properties of the newly defined numbers and indicate directions for further amusement.

  15. Revisiting Hansen Solubility Parameters by Including Thermodynamics

    NARCIS (Netherlands)

    Louwerse, Manuel J; Fernández-Maldonado, Ana María; Rousseau, Simon; Moreau-Masselon, Chloe; Roux, Bernard; Rothenberg, Gadi

    2017-01-01

    The Hansen solubility parameter approach is revisited by implementing the thermodynamics of dissolution and mixing. Hansen's pragmatic approach has earned its spurs in predicting solvents for polymer solutions, but for molecular solutes improvements are needed. By going into the details of entropy

  16. The Future of Engineering Education--Revisited

    Science.gov (United States)

    Wankat, Phillip C.; Bullard, Lisa G.

    2016-01-01

    This paper revisits the landmark CEE series, "The Future of Engineering Education," published in 2000 (available free in the CEE archives on the internet) to examine the predictions made in the original paper as well as the tools and approaches documented. Most of the advice offered in the original series remains current. Despite new…

  17. Revisiting the formal foundation of Probabilistic Databases

    NARCIS (Netherlands)

    Wanders, B.; van Keulen, Maurice

    2015-01-01

    One of the core problems in soft computing is dealing with uncertainty in data. In this paper, we revisit the formal foundation of a class of probabilistic databases with the purpose to (1) obtain data model independence, (2) separate metadata on uncertainty and probabilities from the raw data, (3)

  18. Revisiting Weak Simulation for Substochastic Markov Chains

    DEFF Research Database (Denmark)

    Jansen, David N.; Song, Lei; Zhang, Lijun

    2013-01-01

    of the logic PCTL\\x, and its completeness was conjectured. We revisit this result and show that soundness does not hold in general, but only for Markov chains without divergence. It is refuted for some systems with substochastic distributions. Moreover, we provide a counterexample to completeness...

  19. Coccolithophorids in polar waters: Wigwamma spp. revisited

    DEFF Research Database (Denmark)

    Thomsen, Helge Abildhauge; Østergaard, Jette B.; Heldal, Mikal

    2013-01-01

    A contingent of weakly calcified coccolithophorid genera and species were described from polar regions almost 40 years ago. In the interim period a few additional findings have been reported enlarging the realm of some of the species. The genus Wigwamma is revisited here with the purpose of provi...... appearance of the coccolith armour of the cell...

  20. The Faraday effect revisited: General theory

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

    2006-01-01

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. At zero temperature and zero frequency...

  1. The Faraday effect revisited: General theory

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse...

  2. 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

  3. 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.

  4. Extrinsic doping in silicon revisited

    KAUST Repository

    Schwingenschlögl, Udo

    2010-06-17

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regarding dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  5. Extrinsic doping in silicon revisited

    KAUST Repository

    Schwingenschlö gl, Udo; Chroneos, Alexander; Grimes, R. W.; Schuster, Cosima

    2010-01-01

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regarding dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  6. Eulerian numbers

    CERN Document Server

    Petersen, T Kyle

    2015-01-01

    This text presents the Eulerian numbers in the context of modern enumerative, algebraic, and geometric combinatorics. The book first studies Eulerian numbers from a purely combinatorial point of view, then embarks on a tour of how these numbers arise in the study of hyperplane arrangements, polytopes, and simplicial complexes. Some topics include a thorough discussion of gamma-nonnegativity and real-rootedness for Eulerian polynomials, as well as the weak order and the shard intersection order of the symmetric group. The book also includes a parallel story of Catalan combinatorics, wherein the Eulerian numbers are replaced with Narayana numbers. Again there is a progression from combinatorics to geometry, including discussion of the associahedron and the lattice of noncrossing partitions. The final chapters discuss how both the Eulerian and Narayana numbers have analogues in any finite Coxeter group, with many of the same enumerative and geometric properties. There are four supplemental chapters throughout, ...

  7. eWOM, Revisit Intention, Destination Trust and Gender

    OpenAIRE

    Abubakar, Abubakar Mohammed; Ilkan, Mustafa; Al-Tal, Raad Meshall; Eluwole, Kayode

    2017-01-01

    This article investigates the impact of eWOM on intention to revisit and destination trust, and the moderating role of gender in medical tourism industry. Result from structural equation modeling (n=240) suggests the following: (1) that eWOM influences intention to revisit and destination trust; (2) that destination trust influences intention to revisit; (3) that the impact of eWOM on intention to revisit is about 1.3 times higher in men; (4) that the impact of eWOM on destination trust is ab...

  8. First-Order Quantum Phase Transition for Dicke Model Induced by Atom-Atom Interaction

    International Nuclear Information System (INIS)

    Zhao Xiu-Qin; Liu Ni; Liang Jiu-Qing

    2017-01-01

    In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model’s ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength. (paper)

  9. Transfinite Numbers

    Indian Academy of Sciences (India)

    Transfinite Numbers. What is Infinity? S M Srivastava. In a series of revolutionary articles written during the last quarter of the nineteenth century, the great Ger- man mathematician Georg Cantor removed the age-old mistrust of infinity and created an exceptionally beau- tiful and useful theory of transfinite numbers. This is.

  10. Understanding Atomic Structure: Is There a More Direct and Compelling Connection between Atomic Line Spectra and the Quantization of an Atom's Energy?

    Science.gov (United States)

    Rittenhouse, Robert C.

    2015-01-01

    The "atoms first" philosophy, adopted by a growing number of General Chemistry textbook authors, places greater emphasis on atomic structure as a key to a deeper understanding of the field of chemistry. A pivotal concept needed to understand the behavior of atoms is the restriction of an atom's energy to specific allowed values. However,…

  11. Quantum Electronics for Atomic Physics

    CERN Document Server

    Nagourney, Warren

    2010-01-01

    Quantum Electronics for Atomic Physics provides a course in quantum electronics for researchers in atomic physics. The book covers the usual topics, such as Gaussian beams, cavities, lasers, nonlinear optics and modulation techniques, but also includes a number of areas not usually found in a textbook on quantum electronics. It includes such practical matters as the enhancement of nonlinear processes in a build-up cavity, impedance matching into a cavity, laser frequencystabilization (including servomechanism theory), astigmatism in ring cavities, and atomic/molecular spectroscopic techniques

  12. Review of atomic mass formula

    Energy Technology Data Exchange (ETDEWEB)

    Tachibana, Takahiro [Waseda Univ., Tokyo (Japan). Advanced Research Center for Science and Engineering

    1997-07-01

    Wapstra and Audi`s Table is famous for evaluation of experimental data of atomic nuclear masses (1993/1995 version) which estimated about 2000 kinds of nuclei. The error of atomic mass of formula is 0.3 MeV-0.8 MeV. Four kinds of atomic mass formula: JM (Jaenecke and Masson), TUYY (Tachibana, Uno, Yamada and Yamada), FRDM (Moeller, Nix, Myers and Swiatecki) and ETFSI (Aboussir, Pearson, Dutta and Tondeur) and their properties (number of parameter and error etc.) were explained. An estimation method of theoretical error of mass formula was presented. It was estimated by the theoretical error of other surrounding nuclei. (S.Y.)

  13. Relativistic theory of surficial Love numbers

    Science.gov (United States)

    Landry, Philippe; Poisson, Eric

    2014-06-01

    A relativistic theory of surficial Love numbers, which characterize the surface deformation of a body subjected to tidal forces, was initiated by Damour and Nagar. We revisit this effort in order to extend it, clarify some of its aspects, and simplify its computational implementation. First, we refine the definition of surficial Love numbers proposed by Damour and Nagar and formulate it directly in terms of the deformed curvature of the body's surface, a meaningful geometrical quantity. Second, we develop a unified theory of surficial Love numbers that applies equally well to material bodies and black holes. Third, we derive a compactness-dependent relation between the surficial and (electric-type) gravitational Love numbers of a perfect-fluid body and show that it reduces to the familiar Newtonian relation when the compactness is small. And fourth, we simplify the tasks associated with the practical computation of the surficial and gravitational Love numbers for a material body.

  14. Chocolate Numbers

    OpenAIRE

    Ji, Caleb; Khovanova, Tanya; Park, Robin; Song, Angela

    2015-01-01

    In this paper, we consider a game played on a rectangular $m \\times n$ gridded chocolate bar. Each move, a player breaks the bar along a grid line. Each move after that consists of taking any piece of chocolate and breaking it again along existing grid lines, until just $mn$ individual squares remain. This paper enumerates the number of ways to break an $m \\times n$ bar, which we call chocolate numbers, and introduces four new sequences related to these numbers. Using various techniques, we p...

  15. Number theory

    CERN Document Server

    Andrews, George E

    1994-01-01

    Although mathematics majors are usually conversant with number theory by the time they have completed a course in abstract algebra, other undergraduates, especially those in education and the liberal arts, often need a more basic introduction to the topic.In this book the author solves the problem of maintaining the interest of students at both levels by offering a combinatorial approach to elementary number theory. In studying number theory from such a perspective, mathematics majors are spared repetition and provided with new insights, while other students benefit from the consequent simpl

  16. Nice numbers

    CERN Document Server

    Barnes, John

    2016-01-01

    In this intriguing book, John Barnes takes us on a journey through aspects of numbers much as he took us on a geometrical journey in Gems of Geometry. Similarly originating from a series of lectures for adult students at Reading and Oxford University, this book touches a variety of amusing and fascinating topics regarding numbers and their uses both ancient and modern. The author intrigues and challenges his audience with both fundamental number topics such as prime numbers and cryptography, and themes of daily needs and pleasures such as counting one's assets, keeping track of time, and enjoying music. Puzzles and exercises at the end of each lecture offer additional inspiration, and numerous illustrations accompany the reader. Furthermore, a number of appendices provides in-depth insights into diverse topics such as Pascal’s triangle, the Rubik cube, Mersenne’s curious keyboards, and many others. A theme running through is the thought of what is our favourite number. Written in an engaging and witty sty...

  17. Atomic reactor thermal engineering

    International Nuclear Information System (INIS)

    Kim, Gwang Ryong

    1983-02-01

    This book starts the introduction of atomic reactor thermal engineering including atomic reaction, chemical reaction, nuclear reaction neutron energy and soon. It explains heat transfer, heat production in the atomic reactor, heat transfer of fuel element in atomic reactor, heat transfer and flow of cooler, thermal design of atomic reactor, design of thermodynamics of atomic reactor and various. This deals with the basic knowledge of thermal engineering for atomic reactor.

  18. Atomic energy

    International Nuclear Information System (INIS)

    Ramanna, R.

    1978-01-01

    Development of nuclear science in India, particularly the research and development work at the Bhabha Atomic Research Centre (BARC), Bombay, is described. Among the wide range of materials developed for specific functions under rigorous conditions are nuclear pure grade uranium, zirconium and beryllium, and conventional materials like aluminium, carbon steel and stainless steels. Radioisotopes are produced and used for tracer studies in various fields. Various types of nuclear gauges and nuclear instruments are produced. Radiations have been used to develop new high yielding groundnut mutants with large kernals. The sterile male technique for pest control and radiosterilization technique to process potatoes, onions and marine foods for storage are ready for exploitation. Processes and equipment have been developed for production of electrolytic hydrogen, electrothermal phosphorus and desalinated water. Indigenously manufactured components and materials are now being used for the nuclear energy programme. Indian nuclear power programme strategy is to build heavy water reactors and to utilise their byproduct plutonium and depleted uranium to feed fast breeder reactors which will produce more fissile material than burnt. Finally a special mention has been made of the manpower development programme of the BARC. BARC has established a training school in 1957 giving advanced training in physics, chemistry and various branches of engineering and metallurgy

  19. Quantum mechanical study on hydrogen bonds between 3-aminophenol and CH{sub x}Cl{sub 4-}x (x=1, 2, 3): Effect of the number of halogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Lee, So Young; Kang, Hyuk [Dept. of Chemistry, Ajou University, Suwon (Korea, Republic of)

    2015-03-15

    Hydrogen bonds between 3-aminophenol and three chlorine-substituted methanes (CHCl{sub 3}, CH{sub 2}Cl{sub 2}, and CH{sub 3}Cl) were quantum mechanically studied at MP2/aug-cc-pVDZ level. Several low-energy structures with a hydrogen bond were identified for all chlorinated methanes, and the properties of their C[BOND]H stretching vibrations were investigated. When it is hydrogen-bonded to 3-aminophenol (3AP), the C[BOND]H stretching frequency of CHCl{sub 3} is blue-shifted by 18–54 cm−1, and its IR absorption intensity is 48–74 times increased, depending on the isomer. The symmetric and antisymmetric C[BOND]H stretches of CH{sub 2}Cl{sub 2} and CH{sub 3}Cl are shifted in either direction by a few cm−1 upon hydrogen-bonding to 3AP, and their IR intensity was increased by a few times. It is concluded that all chlorinated methanes can make a π-hydrogen bond to 3AP but only CHCl{sub 3}, the one with the most chlorine atoms, makes a blue-shifting hydrogen bond, or an “antihydrogen bond”.

  20. 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

  1. Number names and number understanding

    DEFF Research Database (Denmark)

    Ejersbo, Lisser Rye; Misfeldt, Morten

    2014-01-01

    This paper concerns the results from the first year of a three-year research project involving the relationship between Danish number names and their corresponding digits in the canonical base 10 system. The project aims to develop a system to help the students’ understanding of the base 10 syste...... the Danish number names are more complicated than in other languages. Keywords: A research project in grade 0 and 1th in a Danish school, Base-10 system, two-digit number names, semiotic, cognitive perspectives....

  2. Entanglement properties between two atoms in the binomial optical field interacting with two entangled atoms

    International Nuclear Information System (INIS)

    Liu Tang-Kun; Zhang Kang-Long; Tao Yu; Shan Chuan-Jia; Liu Ji-Bing

    2016-01-01

    The temporal evolution of the degree of entanglement between two atoms in a system of the binomial optical field interacting with two arbitrary entangled atoms is investigated. The influence of the strength of the dipole–dipole interaction between two atoms, probabilities of the Bernoulli trial, and particle number of the binomial optical field on the temporal evolution of the atomic entanglement are discussed. The result shows that the two atoms are always in the entanglement state. Moreover, if and only if the two atoms are initially in the maximally entangled state, the entanglement evolution is not affected by the parameters, and the degree of entanglement is always kept as 1. (paper)

  3. Number-unconstrained quantum sensing

    Science.gov (United States)

    Mitchell, Morgan W.

    2017-12-01

    Quantum sensing is commonly described as a constrained optimization problem: maximize the information gained about an unknown quantity using a limited number of particles. Important sensors including gravitational wave interferometers and some atomic sensors do not appear to fit this description, because there is no external constraint on particle number. Here, we develop the theory of particle-number-unconstrained quantum sensing, and describe how optimal particle numbers emerge from the competition of particle-environment and particle-particle interactions. We apply the theory to optical probing of an atomic medium modeled as a resonant, saturable absorber, and observe the emergence of well-defined finite optima without external constraints. The results contradict some expectations from number-constrained quantum sensing and show that probing with squeezed beams can give a large sensitivity advantage over classical strategies when each is optimized for particle number.

  4. Electronic structure of atoms: atomic spectroscopy information system

    International Nuclear Information System (INIS)

    Kazakov, V V; Kazakov, V G; Kovalev, V S; Meshkov, O I; Yatsenko, A S

    2017-01-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists. (paper)

  5. Electronic structure of atoms: atomic spectroscopy information system

    Science.gov (United States)

    Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

    2017-10-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

  6. An analytic algorithm for global coverage of the revisiting orbit and its application to the CFOSAT satellite

    Science.gov (United States)

    Xu, Ming; Huang, Li

    2014-08-01

    This paper addresses a new analytic algorithm for global coverage of the revisiting orbit and its application to the mission revisiting the Earth within long periods of time, such as Chinese-French Oceanic Satellite (abbr., CFOSAT). In the first, it is presented that the traditional design methodology of the revisiting orbit for some imaging satellites only on the single (ascending or descending) pass, and the repeating orbit is employed to perform the global coverage within short periods of time. However, the selection of the repeating orbit is essentially to yield the suboptimum from the rare measure of rational numbers of passes per day, which will lose lots of available revisiting orbits. Thus, an innovative design scheme is proposed to check both rational and irrational passes per day to acquire the relationship between the coverage percentage and the altitude. To improve the traditional imaging only on the single pass, the proposed algorithm is mapping every pass into its ascending and descending nodes on the specified latitude circle, and then is accumulating the projected width on the circle by the field of view of the satellite. The ergodic geometry of coverage percentage produced from the algorithm is affecting the final scheme, such as the optimal one owning the largest percentage, and the balance one possessing the less gradient in its vicinity, and is guiding to heuristic design for the station-keeping control strategies. The application of CFOSAT validates the feasibility of the algorithm.

  7. Funny Numbers

    Directory of Open Access Journals (Sweden)

    Theodore M. Porter

    2012-12-01

    Full Text Available The struggle over cure rate measures in nineteenth-century asylums provides an exemplary instance of how, when used for official assessments of institutions, these numbers become sites of contestation. The evasion of goals and corruption of measures tends to make these numbers “funny” in the sense of becoming dis-honest, while the mismatch between boring, technical appearances and cunning backstage manipulations supplies dark humor. The dangers are evident in recent efforts to decentralize the functions of governments and corporations using incen-tives based on quantified targets.

  8. Transcendental numbers

    CERN Document Server

    Murty, M Ram

    2014-01-01

    This book provides an introduction to the topic of transcendental numbers for upper-level undergraduate and graduate students. The text is constructed to support a full course on the subject, including descriptions of both relevant theorems and their applications. While the first part of the book focuses on introducing key concepts, the second part presents more complex material, including applications of Baker’s theorem, Schanuel’s conjecture, and Schneider’s theorem. These later chapters may be of interest to researchers interested in examining the relationship between transcendence and L-functions. Readers of this text should possess basic knowledge of complex analysis and elementary algebraic number theory.

  9. Revisiting Cementoblastoma with a Rare Case Presentation

    Directory of Open Access Journals (Sweden)

    Vijayanirmala Subramani

    2017-01-01

    Full Text Available Cementoblastoma is a rare benign odontogenic neoplasm which is characterized by the proliferation of cellular cementum. Diagnosis of cementoblastoma is challenging because of its protracted clinical, radiographic features, and bland histological appearance; most often cementoblastoma is often confused with other cementum and bone originated lesions. The aim of this article is to overview/revisit, approach the diagnosis of cementoblastoma, and also present a unique radiographic appearance of a cementoblastoma lesion associated with an impacted tooth.

  10. Revisiting an open access monograph experiment: measuring citations and tweets 5 years later.

    Science.gov (United States)

    Snijder, Ronald

    An experiment run in 2009 could not assess whether making monographs available in open access enhanced scholarly impact. This paper revisits the experiment, drawing on additional citation data and tweets. It attempts to answer the following research question: does open access have a positive influence on the number of citations and tweets a monograph receives, taking into account the influence of scholarly field and language? The correlation between monograph citations and tweets is also investigated. The number of citations and tweets measured in 2014 reveal a slight open access advantage, but the influence of language or subject should also be taken into account. However, Twitter usage and citation behaviour hardly overlap.

  11. Transfinite Numbers

    Indian Academy of Sciences (India)

    this is a characteristic difference between finite and infinite sets and created an immensely useful branch of mathematics based on this idea which had a great impact on the whole of mathe- matics. For example, the question of what is a number (finite or infinite) is almost a philosophical one. However Cantor's work turned it ...

  12. Atom Optics in a Nutshell

    Science.gov (United States)

    Meystre, Pierre

    This chapter presents a brief introduction to atom optics, assuming only a basic knowledge of elementary physics ideas such as conservation of energy and conservation of momentum, and making only limited use of elementary algebra. Starting from a historical perspective we introduce the idea of wave-particle duality, a fundamental tenet of quantum mechanics that teaches us that atoms, just like light, behave sometimes as waves, and sometimes as particles. It is this profound but counter-intuitive property that allows one to do with atoms much of what is familiar from conventional optics. However, because in contrast to photons atoms have a mass, there are also fundamental differences between the two that have important consequences. In particular this property opens up a number of applications that are ill-suited for conventional optical methods. After explaining why it is particularly advantageous to work at temperatures close to absolute zero to benefit most readily from the wave nature of atoms we discuss several of these applications, concentrating primarily on the promise of atom microscopes and atom interferometers in addressing fundamental and extraordinarily challenging questions at the frontier of current physics knowledge.

  13. Ghost imaging with atoms

    Science.gov (United States)

    Khakimov, R. I.; Henson, B. M.; Shin, D. K.; Hodgman, S. S.; Dall, R. G.; Baldwin, K. G. H.; Truscott, A. G.

    2016-12-01

    Ghost imaging is a counter-intuitive phenomenon—first realized in quantum optics—that enables the image of a two-dimensional object (mask) to be reconstructed using the spatio-temporal properties of a beam of particles with which it never interacts. Typically, two beams of correlated photons are used: one passes through the mask to a single-pixel (bucket) detector while the spatial profile of the other is measured by a high-resolution (multi-pixel) detector. The second beam never interacts with the mask. Neither detector can reconstruct the mask independently, but temporal cross-correlation between the two beams can be used to recover a ‘ghost’ image. Here we report the realization of ghost imaging using massive particles instead of photons. In our experiment, the two beams are formed by correlated pairs of ultracold, metastable helium atoms, which originate from s-wave scattering of two colliding Bose-Einstein condensates. We use higher-order Kapitza-Dirac scattering to generate a large number of correlated atom pairs, enabling the creation of a clear ghost image with submillimetre resolution. Future extensions of our technique could lead to the realization of ghost interference, and enable tests of Einstein-Podolsky-Rosen entanglement and Bell’s inequalities with atoms.

  14. Efficient Atomic One-Qubit Phase Gate Realized by a Cavity QED and Identical Atoms System

    International Nuclear Information System (INIS)

    He Yong; Jiang Nianquan

    2010-01-01

    We present a scheme to implement a one-qubit phase gate with a two-level atom crossing an optical cavity in which some identical atoms are trapped. One can conveniently acquire an arbitrary phase shift of the gate by properly choosing the number of atoms trapped in the cavity and the velocity of the atom crossing the cavity. The present scheme provides a very simple and efficient way for implementing one-qubit phase gate. (general)

  15. 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

  16. Phantom atom

    International Nuclear Information System (INIS)

    Ludwig, K.; Voigt, S.

    1993-01-01

    The Society for People Living under Threat has been supporting those affected by radiation (Uranium decay), nuclear weapons testing, nuclear power stations and waste disposal since the mid-sixties. Through a great number of meetings, press releases and campaigns, it has succeeded in bringing the theme into the public spotlight in Germany, particularly within the ecology movement. The initial hesitation in supporting the indigenous peoples threatened by radiation contamination has given way to broad consensus and support. The ecology and human rights movement have united the need to listen to and give support to those of whom no-one speaks. (orig./DG) [de

  17. 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

  18. 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)

  19. Precision in single atom localization via Raman-driven coherence: Role of detuning and phase shift

    Energy Technology Data Exchange (ETDEWEB)

    Rahmatullah,; Qamar, Sajid, E-mail: sajid_qamar@comsats.edu.pk

    2013-10-01

    Role of detuning and phase shift associated with the standing-wave driving fields is revisited for precision position measurement of single atom during its motion through two standing-wave fields. A four-level atomic system in diamond configuration is considered where the intermediate levels are coupled to upper and lower level via standing-wave driving fields and atomic decay channels, respectively. The former is responsible for the generation of quantum mechanical coherence via two-photon Raman transition while the latter leads to spontaneous emission of a photon. Due to standing-wave driving fields the atom–field interaction becomes position-dependent and measurement of the frequency of spontaneously emitted photon gives the position information of the atom. The unique position of the atom with much higher spatial resolution, i.e., of the order of λ/100 is observed using detuning and phase shift associated with the standing-wave driving fields.

  20. 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.)

  1. Push-Pull Laser-Atomic Oscillator

    International Nuclear Information System (INIS)

    Jau, Y.-Y.; Happer, W.

    2007-01-01

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the 'field-independent 0-0 frequency' of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs

  2. Spectroscopy, Understanding the Atom Series.

    Science.gov (United States)

    Hellman, Hal

    This booklet is one of the "Understanding the Atom" Series. The science of spectroscopy is presented by a number of topics dealing with (1) the uses of spectroscopy, (2) its origin and background, (3) the basic optical systems of spectroscopes, spectrometers, and spectrophotometers, (4) the characteristics of wave motion, (5) the…

  3. Shukla-Eliasson attractive force: Revisited

    Science.gov (United States)

    Akbari-Moghanjoughi, M.; Akbari-Moghanjoughi

    2013-04-01

    By investigating the dielectric response of the Fermi-Dirac plasma in the linear limit and evaluating the electrostatic potential around the positive stationary test charge, we find that the Shukla-Eliasson attractive force is present for the plasma density range expected in the interiors of large planets for a wide range of plasma atomic number. This research, which is based on the generalized electron Fermi-momentum, further confirms the existence of the newly discovered Lennard-Jones-like attractive potential and its inevitable role in plasma crystallization in the cores of planets. Moreover, it is observed that the characteristics of the attractive potential are strongly sensitive to the variation of plasma density and composition. Current research can also have applications in the study of strong laser-matter interactions and inertially confined plasmas.

  4. Gauge theory for baryon and lepton numbers with leptoquarks.

    Science.gov (United States)

    Duerr, Michael; Fileviez Pérez, Pavel; Wise, Mark B

    2013-06-07

    Models where the baryon (B) and lepton (L) numbers are local gauge symmetries that are spontaneously broken at a low scale are revisited. We find new extensions of the standard model which predict the existence of fermions that carry both baryon and lepton numbers (i.e., leptoquarks). The local baryonic and leptonic symmetries can be broken at a scale close to the electroweak scale and we do not need to postulate the existence of a large desert to satisfy the experimental constraints on baryon number violating processes like proton decay.

  5. Atomic fountain and applications

    International Nuclear Information System (INIS)

    Rawat, H.S.

    2000-01-01

    An overview of the development of working of MOT along with the basic principle of laser atom cooling and trapping is given. A technique to separate the cooled and trapped atoms from the MOT using atomic fountain technique will also be covered. The widely used technique for atomic fountain is, first to cool and trap the neutral atoms in MOT and then launch them in the vertical direction, using moving molasses technique. Using 133 Cs atomic fountain clock, time improvement of 2 to 3 order of magnitude over a conventional 133 Cs atomic clock has been observed

  6. Interferometry with atoms

    International Nuclear Information System (INIS)

    Helmcke, J.; Riehle, F.; Witte, A.; Kisters, T.

    1992-01-01

    Physics and experimental results of atom interferometry are reviewed and several realizations of atom interferometers are summarized. As a typical example of an atom interferometer utilizing the internal degrees of freedom of the atom, we discuss the separated field excitation of a calcium atomic beam using four traveling laser fields and demonstrate the Sagnac effect in a rotating interferometer. The sensitivity of this interferometer can be largely increased by use of slow atoms with narrow velocity distribution. We therefore furthermore report on the preparation of a laser cooled and deflected calcium atomic beam. (orig.)

  7. Entanglement detection from interference fringes in atom-photon systems

    International Nuclear Information System (INIS)

    Suzuki, Jun; Nemoto, Kae; Miniatura, Christian

    2010-01-01

    A measurement scheme of atomic qubits pinned at given positions is studied by analyzing the interference pattern obtained when they emit photons spontaneously. In the case of two qubits, a well-known relation is revisited in which the interference visibility is equal to the concurrence of the state in the infinite spatial separation limit of the qubits. By taking into account the superradiant and subradiant effects, it is shown that a state tomography is possible when the qubit spatial separation is comparable to the wavelength of the atomic transition. In the case of three qubits, the relations between various entanglement measures and the interference visibility are studied, where the visibility is defined from the two-qubit case. A qualitative correspondence among these entanglement relations is discussed. In particular, it is shown that the interference visibility is directly related to the maximal bipartite negativity.

  8. The entanglement evolution between two entangled atoms

    Indian Academy of Sciences (India)

    ... entanglement between the two atoms changes periodically and undergoes the entanglement sudden death (ESD) and sudden birth at some time. The entanglement properties between the field and the atom insidethe cavity are dependent on the photon number. Most interestingly, the entanglement between the field and ...

  9. The evolution of the mitochondrial genetic code in arthropods revisited.

    Science.gov (United States)

    Abascal, Federico; Posada, David; Zardoya, Rafael

    2012-04-01

    A variant of the invertebrate mitochondrial genetic code was previously identified in arthropods (Abascal et al. 2006a, PLoS Biol 4:e127) in which, instead of translating the AGG codon as serine, as in other invertebrates, some arthropods translate AGG as lysine. Here, we revisit the evolution of the genetic code in arthropods taking into account that (1) the number of arthropod mitochondrial genomes sequenced has triplicated since the original findings were published; (2) the phylogeny of arthropods has been recently resolved with confidence for many groups; and (3) sophisticated probabilistic methods can be applied to analyze the evolution of the genetic code in arthropod mitochondria. According to our analyses, evolutionary shifts in the genetic code have been more common than previously inferred, with many taxonomic groups displaying two alternative codes. Ancestral character-state reconstruction using probabilistic methods confirmed that the arthropod ancestor most likely translated AGG as lysine. Point mutations at tRNA-Lys and tRNA-Ser correlated with the meaning of the AGG codon. In addition, we identified three variables (GC content, number of AGG codons, and taxonomic information) that best explain the use of each of the two alternative genetic codes.

  10. 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

  11. 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.)

  12. Atoms in strong laser fields

    International Nuclear Information System (INIS)

    L'Huillier, A.

    2002-01-01

    When a high-power laser focuses into a gas of atoms, the electromagnetic field becomes of the same magnitude as the Coulomb field which binds a 1s electron in a hydrogen atom. 3 highly non-linear phenomena can happen: 1) ATI (above threshold ionization): electrons initially in the ground state absorb a large number of photons, many more than the minimum number required for ionization; 2) multiple ionization: many electrons can be emitted one at a time, in a sequential process, or simultaneously in a mechanism called direct or non-sequential; and 3) high order harmonic generation (HHG): efficient photon emission in the extreme ultraviolet range, in the form of high-order harmonics of the fundamental laser field can occur. The theoretical problem consists in solving the time dependent Schroedinger equation (TDSE) that describes the interaction of a many-electron atom with a laser field. A number of methods have been proposed to solve this problem in the case of a hydrogen atom or a single-active electron atom in a strong laser field. A large effort is presently being devoted to go beyond the single-active approximation. The understanding of the physics of the interaction between atoms and strong laser fields has been provided by a very simple model called ''simple man's theory''. A unified view of HHG, ATI, and non-sequential ionization, originating from the simple man's model and the strong field approximation, expressed in terms of electrons trajectories or quantum paths is slowly emerging. (A.C.)

  13. Advanced Change Theory Revisited: An Article Critique

    Directory of Open Access Journals (Sweden)

    R. Scott Pochron

    2008-12-01

    Full Text Available The complexity of life in 21st century society requires new models for leading and managing change. With that in mind, this paper revisits the model for Advanced Change Theory (ACT as presented by Quinn, Spreitzer, and Brown in their article, “Changing Others Through Changing Ourselves: The Transformation of Human Systems” (2000. The authors present ACT as a potential model for facilitating change in complex organizations. This paper presents a critique of the article and summarizes opportunities for further exploring the model in the light of current trends in developmental and integral theory.

  14. Resolution of Reflection Seismic Data Revisited

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Mosegaard, Klaus; Zunino, Andrea

    The Rayleigh Principle states that the minimum separation between two reflectors that allows them to be visually separated is the separation where the wavelet maxima from the two superimposed reflections combine into one maximum. This happens around Δtres = λb/8, where λb is the predominant...... lower vertical resolution of reflection seismic data. In the following we will revisit think layer model and demonstrate that there is in practice no limit to the vertical resolution using the parameterization of Widess (1973), and that the vertical resolution is limited by the noise in the data...

  15. Large J expansion in ABJM theory revisited.

    Science.gov (United States)

    Dimov, H; Mladenov, S; Rashkov, R C

    Recently there has been progress in the computation of the anomalous dimensions of gauge theory operators at strong coupling by making use of the AdS/CFT correspondence. On the string theory side they are given by dispersion relations in the semiclassical regime. We revisit the problem of a large-charge expansion of the dispersion relations for simple semiclassical strings in an [Formula: see text] background. We present the calculation of the corresponding anomalous dimensions of the gauge theory operators to an arbitrary order using three different methods. Although the results of the three methods look different, power series expansions show their consistency.

  16. Sloan Digital Sky Survey Photometric Calibration Revisited

    International Nuclear Information System (INIS)

    Marriner, John

    2012-01-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  17. Revisiting the Political Economy of Communication

    Directory of Open Access Journals (Sweden)

    Nicholas Garnham

    2014-02-01

    The task of the paper and the seminar was to revisit some of Nicholas Garnham’s ideas, writings and contributions to the study of the Political Economy of Communication and to reflect on the concepts, history, current status and perspectives of this field and the broader study of political economy today. The topics covered include Raymond Williams’ cultural materialism, Pierre Bourdieu’s sociology of culture, the debate between Political Economy and Cultural Studies, information society theory, Karl Marx’s theory and the critique of capitalism.

  18. Sloan Digital Sky Survey Photometric Calibration Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  19. Atomic squeezed states on an atom-chip

    International Nuclear Information System (INIS)

    Maussang, Kenneth

    2010-01-01

    In this thesis, we describe the construction of an experiment, allowing to produce 87 Rb Bose-Einstein condensates on an atom chip, and then split them in a double well potential. An accurate imaging system has been developed, in order to be able to measure the absolute value of the populations of the double well within a very low noise level, almost limited by the optical shot noise. We measure atom number statistics after splitting, and directly observe number squeezed states, down to -4.9 dB at low temperatures, compared to a classical gas, of independent particles. The dependence in temperature of fluctuations has been also studied. For a thermal gas, Poissonian fluctuations are given by the probability distribution of the macroscopic configurations with a given atom number difference. In the degenerate regime, the entropy effect which favors small number differences vanishes, leading to super-Poissonian fluctuations, to more than +3.8 dB close to transition temperature. At low temperatures, the interaction energy cost associated with number fluctuations exceeds the available thermal energy, leading to sub-Poissonian fluctuations. Those two behaviours have been theoretically explained, both with a simple analytical model and a numerical one. We also measured the evolution of the relative phase between the two clouds, and its collapse due to interactions, allowing us to claim that this splitter is a coherent one. (author)

  20. PROTONATED POLYCYCLIC AROMATIC HYDROCARBONS REVISITED

    International Nuclear Information System (INIS)

    Ricca, Alessandra; Bauschlicher, Charles W. Jr; Allamandola, Louis J.

    2011-01-01

    We reconsider the contribution that singly protonated polycyclic aromatic hydrocarbons (PAHs; HPAH + s) might make to the Class A component of the 6.2 μm interstellar emission feature in light of the recent experimental measurements of protonated naphthalene and coronene. Our calculations on the small HPAH + s have a band near 6.2 μm, as found in experiment. While the larger HPAH + s still have emission near 6.2 μm, the much larger intensity of the band near 6.3 μm overwhelms the weaker band at 6.2 μm, so that the 6.2 μm band is barely visible. Since the large PAHs are more representative of those in the interstellar medium, our work suggests that large HPAH + s cannot be major contributors to the observed emission at 6.2 μm (i.e., Class A species). Saturating large PAH cations with hydrogen atoms retains the 6.2 μm Class A band position, but the rest of the spectrum is inconsistent with observed spectra.

  1. Silent cries, dancing tears: the metapsychology of art revisited/revised.

    Science.gov (United States)

    Aragno, Anna

    2011-04-01

    Against the backdrop of a broad survey of the literature on applied psychoanalysis, a number of concepts underpinning the metapsychology of art are revisited and revised: sublimation; interrelationships between primary and secondary processes; symbolization; "fantasy"; and "cathexis." Concepts embedded in dichotomous or drive/energic contexts are examined and reformulated in terms of a continuum of semiotic processes. Freudian dream structure is viewed as a biological/natural template for nonrepressive artistic forms of sublimation. The synthesis presented proposes a model of continuous rather than discontinuous processes, in a nonenergic, biosemiotic metatheoretical framework.

  2. The odd one out: Revisiting and investigating the gender imbalance in ICT study choices

    Directory of Open Access Journals (Sweden)

    Scott Morton

    Full Text Available For the past two decades there has been an imbalance between male and female students entering the Bachelor of Information Technology degree from high schools. The literature suggests that only one in six students entering higher education to study computer related degrees are female. It also suggests that occupational stereotyping can be linked to the decline in the number of females entering computing degree courses. This research is proposing to revisit and investigate why this is still prevalent in today\\'s society that has been brought up on technology and can see the benefits of good careers and good jobs.

  3. Hot atom chemistry of sulphur

    International Nuclear Information System (INIS)

    Todorovski, D. S.; Koleva, D. P.

    1982-01-01

    An attempt to cover all papers dealing with the hot atom chemistry of sulpphur is made. Publications which: a) only touch the problem, b) contain some data, indirectly connected with sulphur hot atom chemistry, c) deal with 35 S-production from a chloride matrix, are included as well. The author's name and literature source are given in the original language, transcribed, when it is necessary, in latine. A number of primery and secondary documents have been used including Chemical Abstracts, INIS Atomindex, the bibliographies of A. Siuda and J.-P. Adloff for 1973 - 77, etc. (authors)

  4. Atomic structure in black hole

    International Nuclear Information System (INIS)

    Nagatani, Yukinori

    2006-01-01

    We propose that any black hole has atomic structure in its inside and has no horizon as a model of black holes. Our proposal is founded on a mean field approximation of gravity. The structure of our model consists of a (charged) singularity at the center and quantum fluctuations of fields around the singularity, namely, it is quite similar to that of atoms. Any properties of black holes, e.g. entropy, can be explained by the model. The model naturally quantizes black holes. In particular, we find the minimum black hole, whose structure is similar to that of the hydrogen atom and whose Schwarzschild radius is approximately 1.1287 times the Planck length. Our approach is conceptually similar to Bohr's model of the atomic structure, and the concept of the minimum Schwarzschild radius is similar to that of the Bohr radius. The model predicts that black holes carry baryon number, and the baryon number is rapidly violated. This baryon number violation can be used as verification of the model. (author)

  5. Reflection Revisited: The Class Collage

    Science.gov (United States)

    Sommers, Jeff

    2011-01-01

    Through the regular use of what Donald Schon has termed reflection-in-action and reflection-on-action, students can learn to improve their "reflection-in-presentation," in Kathleen Blake Yancey's term. Students are often asked to do this type of reflection-in-presentation as a capstone to first-year or basic writing courses. However, a number of…

  6. Short wavelength sources and atoms and ions

    International Nuclear Information System (INIS)

    Kennedy, E.T.

    2008-01-01

    The interaction of ionizing radiation with atoms and ions is a key fundamental process. Experimental progress has depended in particular on the development of short wavelength light sources. Laser-plasma and synchrotron sources have been exploited for several decades and most recently the development of short wavelength Free Electron Laser (FEL) sources is revolutionizing the field. This paper introduces laser plasma and synchrotron sources through examples of their use in studies of the interaction of ionizing radiation with atoms and ions, ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides. The new FEL source (FLASH) at DESY is introduced. (author)

  7. Cold atoms in optical cavities and lattices

    International Nuclear Information System (INIS)

    Horak, P.

    1996-11-01

    The thesis is organized in three chapters covering different aspects of the interaction of atoms and light in the framework of theoretical quantum optics. In chapter 1 a special case of a microscopic laser where one or two atoms interact with several quantized cavity modes is discussed. In particular I investigate the properties of the light field created in one of the cavity modes. It is shown that a single-atom model already predicts average photon numbers in agreement with a semiclassical many-atom theory. The two-atom model exhibits additional collective features, such as superradiance and subradiance. In chapter 2 effects of the photon recoil on cold atoms in the limit of long-lived atomic transitions are investigated. First, I demonstrate that, in principle, relying on this scheme, a continuous-wave laser in the ultraviolet frequency domain could be established. Second, the splitting of an atomic beam into two coherent subbeams is discussed within the same scheme. Such beamsplitters play an important role in high-precision measurements using atomic interferometers. Finally, chapter 3 deals with cooling and trapping of atoms by the interaction with laser light. I discuss the properties and the light scattering of atoms trapped in a new light field configuration, a so-called dark optical superlattice. In principle, such systems allow the trapping of more than one atom in the ground state of a single optical potential well. This could give rise to the observation of e.g. atom-atom interactions and quantum statistical effects. (author)

  8. 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...

  9. 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...

  10. 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.

  11. Progress in atomic spectroscopy

    International Nuclear Information System (INIS)

    Beyer, H.J.; Kleinpoppen, H.

    1984-01-01

    This book presents reviews by leading experts in the field covering areas of research at the forefront of atomic spectroscopy. Topics considered include the k ordering of atomic structure, multiconfiguration Hartree-Fock calculations for complex atoms, new methods in high-resolution laser spectroscopy, resonance ionization spectroscopy (inert atom detection), trapped ion spectroscopy, high-magnetic-field atomic physics, the effects of magnetic and electric fields on highly excited atoms, x rays from superheavy collision systems, recoil ion spectroscopy with heavy ions, investigations of superheavy quasi-atoms via spectroscopy of electron rays and positrons, impact ionization by fast projectiles, and amplitudes and state parameters from ion- and atom-atom excitation processes

  12. Preparation of Ultracold Atom Clouds at the Shot Noise Level

    DEFF Research Database (Denmark)

    Gajdacz, M.; Hilliard, A. J.; Kristensen, Mick

    2016-01-01

    We prepare number stabilized ultracold atom clouds through the real-time analysis of nondestructive images and the application of feedback. In our experiments, the atom number N∼10^6 is determined by high precision Faraday imaging with uncertainty ΔN below the shot noise level, i.e., ΔN... on this measurement, feedback is applied to reduce the atom number to a user-defined target, whereupon a second imaging series probes the number stabilized cloud. By this method, we show that the atom number in ultracold clouds can be prepared below the shot noise level....

  13. Theoretical Calculation of Absolute Radii of Atoms and Ions. Part 1. The Atomic Radii

    Directory of Open Access Journals (Sweden)

    Raka Biswas

    2002-02-01

    Full Text Available Abstract. A set of theoretical atomic radii corresponding to the principal maximum in the radial distribution function, 4πr2R2 for the outermost orbital has been calculated for the ground state of 103 elements of the periodic table using Slater orbitals. The set of theoretical radii are found to reproduce the periodic law and the Lother Meyer’s atomic volume curve and reproduce the expected vertical and horizontal trend of variation in atomic size in the periodic table. The d-block and f-block contractions are distinct in the calculated sizes. The computed sizes qualitatively correlate with the absolute size dependent properties like ionization potentials and electronegativity of elements. The radii are used to calculate a number of size dependent periodic physical properties of isolated atoms viz., the diamagnetic part of the atomic susceptibility, atomic polarizability and the chemical hardness. The calculated global hardness and atomic polarizability of a number of atoms are found to be close to the available experimental values and the profiles of the physical properties computed in terms of the theoretical atomic radii exhibit their inherent periodicity. A simple method of computing the absolute size of atoms has been explored and a large body of known material has been brought together to reveal how many different properties correlate with atomic size.

  14. Electron microscopy at atomic resolution

    Energy Technology Data Exchange (ETDEWEB)

    Gronsky, R.

    1983-11-01

    The direct imaging of atomic structure in solids has become increasingly easier to accomplish with modern transmission electron microscopes, many of which have an information retrieval limit near 0.2 nm point resolution. Achieving better resolution, particularly with any useful range of specimen tilting, requires a major design effort. This presentation describes the new Atomic Resolution Microscope (ARM), recently put into operation at the Lawrence Berkeley Laboratory. Capable of 0.18 nm or better interpretable resolution over a voltage range of 400 kV to 1000 kV with +- 40/sup 0/ biaxial specimen tilting, the ARM features a number of new electron-optical and microprocessor-control designs. These are highlighted, and its atomic resolution performance demonstrated for a selection of inorganic crystals.

  15. Electron microscopy at atomic resolution

    International Nuclear Information System (INIS)

    Gronsky, R.

    1983-11-01

    The direct imaging of atomic structure in solids has become increasingly easier to accomplish with modern transmission electron microscopes, many of which have an information retrieval limit near 0.2 nm point resolution. Achieving better resolution, particularly with any useful range of specimen tilting, requires a major design effort. This presentation describes the new Atomic Resolution Microscope (ARM), recently put into operation at the Lawrence Berkeley Laboratory. Capable of 0.18 nm or better interpretable resolution over a voltage range of 400 kV to 1000 kV with +- 40 0 biaxial specimen tilting, the ARM features a number of new electron-optical and microprocessor-control designs. These are highlighted, and its atomic resolution performance demonstrated for a selection of inorganic crystals

  16. Gaming addiction in adolescence (revisited)

    OpenAIRE

    Griffiths, MD

    2014-01-01

    Gaming addiction has become a topic of increasing research interest. Over the last 25 years, I have written many articles on adolescent video gaming for Education and Health as it is one of the research fields that is constantly evolving. In fact, over the last decade, there has been a significant increase in the number of scientific studies examining various aspects of online addiction particularly among adolescents and young adults (Kuss & Griffiths, 2012; Kuss, Griffiths, Karila & Billieux...

  17. Revisiting the eclipse of Darwinism.

    Science.gov (United States)

    Bowler, Peter J

    2005-01-01

    The article sums up a number of points made by the author concerning the response to Darwinism in the late nineteenth and early twentieth centuries, and repeats the claim that a proper understanding of the theory's impact must take account of the extent to which what are now regarded as the key aspects of Darwin's thinking were evaded by his immediate followers. Potential challenges to this position are described and responded to.

  18. Information entropy properties of the atoms in the system of coupled Λ-type three-level atoms interacting with coherent field in Kerr medium

    International Nuclear Information System (INIS)

    Li Ke; Ling Weijun

    2011-01-01

    The information entropy properties of the atoms of coupled Λ-type three-level atoms interacting with coherent field are studied by means of quantum theory, and discussed the time evolutions of the information entropy of the atoms via the average photon number, initial state of the atoms, detuning, coupling constant between the atoms and the coefficient of Kerr medium. Numerical calculation results show that the time evolutions of the information entropy properties of the atoms strongly dependent on the initial state of the system and the average photon number. Detuning, coupling constant between the atoms and the Kerr coefficient still make influence on the information entropy of the atoms. (authors)

  19. Atomic iodine laser

    International Nuclear Information System (INIS)

    Fisk, G.A.; Gusinow, M.A.; Hays, A.K.; Padrick, T.D.; Palmer, R.E.; Rice, J.K.; Truby, F.K.; Riley, M.E.

    1978-05-01

    The atomic iodine photodissociation laser has been under intensive study for a number of years. The physics associated with this system is now well understood and it is possible to produce a 0.1 nsec (or longer) near-diffraction-limited laser pulse which can be amplified with negligible temporal distortion and little spatial deformation. The output of either a saturated or unsaturated amplifier consists of a high-fidelity near-diffraction-limited, energetic laser pulse. The report is divided into three chapters. Chapter 1 is a survey of the important areas affecting efficient laser operation and summarizes the findings of Chap. 2. Chapter 2 presents detailed discussions and evaluations pertinent to pumps, chemical regeneration, and other elements in the overall laser system. Chapter 3 briefly discusses those areas that require further work and the nature of the work required to complete the full-scale evaluation of the applicability of the iodine photodissociation laser to the inertial confinement program

  20. Transient localization in the kicked Rydberg atom

    OpenAIRE

    Persson, E.; Fürthauer, S.; Wimberger, S.; Burgdörfer, J.

    2006-01-01

    We investigate the long-time limit of quantum localization of the kicked Rydberg atom. The kicked Rydberg atom is shown to possess in addition to the quantum localization time $\\tau_L$ a second cross-over time $t_D$ where quantum dynamics diverges from classical dynamics towards increased instability. The quantum localization is shown to vanish as either the strength of the kicks at fixed principal quantum number or the quantum number at fixed kick strength increases. The survival probability...

  1. Revisiting four scientific debates in ocean acidification research

    Directory of Open Access Journals (Sweden)

    A. J. Andersson

    2012-03-01

    Full Text Available In recent years, ocean acidification has gained continuously increasing attention from scientists and a number of stakeholders and has raised serious concerns about its effects on marine organisms and ecosystems. With the increase in interest, funding resources, and the number of scientific investigations focusing on this environmental problem, increasing amounts of data and results have been produced, and a progressively growing and more rigorous understanding of this problem has begun to develop. Nevertheless, there are still a number of scientific debates, and in some cases misconceptions, that keep reoccurring at a number of forums in various contexts. In this article, we revisit four of these topics that we think require further thoughtful consideration including: (1 surface seawater CO2 chemistry in shallow water coastal areas, (2 experimental manipulation of marine systems using CO2 gas or by acid addition, (3 net versus gross calcification and dissolution, and (4 CaCO3 mineral dissolution and seawater buffering. As a summation of these topics, we emphasize that: (1 many coastal environments experience seawater pCO2 that is significantly higher than expected from equilibrium with the atmosphere and is strongly linked to biological processes; (2 addition of acid, base or CO2 gas to seawater can all be useful techniques to manipulate seawater chemistry in ocean acidification experiments; (3 estimates of calcification or CaCO3 dissolution based on present techniques are measuring the net of gross calcification and dissolution; and (4 dissolution of metastable carbonate mineral phases will not produce sufficient alkalinity to buffer the pH and carbonate saturation state of shallow water environments on timescales of decades to hundreds of years to the extent that any potential negative effects on marine calcifiers will be avoided.

  2. PERCEPTION OF JUSTICE, POST SERVICE RECOVERY SATISFACTION, INTENTION TO REVISIT AND WOM RECOMMENDATIONS OF FOREIGN TOURISTS VISITING BALI

    Directory of Open Access Journals (Sweden)

    I Nyoman Sudiarta

    2014-03-01

    Full Text Available This study aimed to determine the effect of perceptions of distributive, procedural and interactional justice on post-service recovery satisfaction and post-service recovery satisfaction effect on the intention to revisit and WOM recommendations of foreign tourists to Bali. The respondents of this study were foreign tourists who visited Bali and ever experienced complaint. The number of eligible samples was 100 respondents. The questionnaire was given to tourists visiting tourist attractions of Tanah Lot, Kintamani and Besakih. Data were analyzed using multivariate statistical analysis, namely structural equation modeling (SEM. The results of this study indicated that the perception of distributive justice, procedural and interactional had a positive and significant effect on the post-service recovery satisfaction of foreign tourists who visited Bali. The study also found a positive and significant effect of post-service recovery satisfaction on the intention to revisit and the intention of recommending positive WOM of foreign tourists who visited Bali.

  3. Resonance ionization spectroscopy: Counting noble gas atoms

    International Nuclear Information System (INIS)

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-01-01

    The purpose of this paper is to describe new work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions). When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. We show that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective. (orig./FKS)

  4. Filter-extruded liposomes revisited

    DEFF Research Database (Denmark)

    Hinna, Askell; Steiniger, Frank; Hupfeld, Stefan

    2016-01-01

    (pore-size, number of filter passages, and flow-rate), flow field-flow fractionation in conjunction with multi-angle laser light scattering (AF4-MALLS, Wyatt Technology Corp., Santa Barbara, CA) was employed. Liposome size-distributions determined by AF4-MALLS were compared with those of dynamic light...... is suggested to prepare large (300 nm) liposomes with rather narrow size distribution, based on the filter extrusion at defined flow-rates in combination with freeze-/ thaw-cycling and bench-top centrifugation....

  5. Transitional boundary layer in low-Prandtl-number convection at high Rayleigh number

    Science.gov (United States)

    Schumacher, Joerg; Bandaru, Vinodh; Pandey, Ambrish; Scheel, Janet

    2016-11-01

    The boundary layer structure of the velocity and temperature fields in turbulent Rayleigh-Bénard flows in closed cylindrical cells of unit aspect ratio is revisited from a transitional and turbulent viscous boundary layer perspective. When the Rayleigh number is large enough the boundary layer dynamics at the bottom and top plates can be separated into an impact region of downwelling plumes, an ejection region of upwelling plumes and an interior region (away from side walls) that is dominated by a shear flow of varying orientation. This interior plate region is compared here to classical wall-bounded shear flows. The working fluid is liquid mercury or liquid gallium at a Prandtl number of Pr = 0 . 021 for a range of Rayleigh numbers of 3 ×105 Deutsche Forschungsgemeinschaft.

  6. Measurement of atomic number and mass attenuation coefficient in ...

    Indian Academy of Sciences (India)

    literature on the measurement of mass attenuation coefficient in magnesium ferrite. The knowledge of photon ... pure) MgO and Fe2O3. The details of experimental ... and (4 4 0) planes belonging to cubic spinel structure. The XRD pattern ...

  7. Experimental measurement of effective atomic number of composite ...

    Indian Academy of Sciences (India)

    2011-08-02

    Aug 2, 2011 ... composite materials for Compton effect in the γ-ray region ... range. The method was employed to evaluate Zeff for different inorganic ... cations of radiation such as dosimetry, shielding, industrial radiography etc., in the photon.

  8. Effective atomic number, electron density and kerma of gamma ...

    Indian Academy of Sciences (India)

    rare element optical glass with oxides of tungsten, tantalum and thorium. ... Similarly, gadolinium and lutetium exhibit only +3 oxidation state because .... (σa) and effective molecular cross-section (σm) are related by the following equation: σa =.

  9. High effective atomic number polymer scintillators for gamma ray spectroscopy

    Science.gov (United States)

    Cherepy, Nerine Jane; Sanner, Robert Dean; Payne, Stephen Anthony; Rupert, Benjamin Lee; Sturm, Benjamin Walter

    2014-04-15

    A scintillator material according to one embodiment includes a bismuth-loaded aromatic polymer having an energy resolution at 662 keV of less than about 10%. A scintillator material according to another embodiment includes a bismuth-loaded aromatic polymer having a fluor incorporated therewith and an energy resolution at 662 keV of less than about 10%. Additional systems and methods are also presented.

  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. Atom chips: mesoscopic physics with cold atoms

    International Nuclear Information System (INIS)

    Krueger, P.; Wildermuth, S.; Hofferberth, S.; Haller, E.; GAllego Garcia, D.; Schmiedmayer, J.

    2005-01-01

    Full text: Cold neutral atoms can be controlled and manipulated in microscopic potentials near surfaces of atom chips. These integrated micro-devices combine the known techniques of atom optics with the capabilities of well established micro- and nanofabrication technology. In analogy to electronic microchips and integrated fiber optics, the concept of atom chips is suitable to explore the domain of mesoscopic physics with matter waves. We use current and charge carrying structures to form complex potentials with high spatial resolution only microns from the surface. In particular, atoms can be confined to an essentially one-dimensional motion. In this talk, we will give an overview of our experiments studying the manipulation of both thermal atoms and BECs on atom chips. First experiments in the quasi one-dimensional regime will be presented. These experiments profit from strongly reduced residual disorder potentials caused by imperfections of the chip fabrication with respect to previously published experiments. This is due to our purely lithographic fabrication technique that proves to be advantageous over electroplating. We have used one dimensionally confined BECs as an ultra-sensitive probe to characterize these potentials. These smooth potentials allow us to explore various aspects of the physics of degenerate quantum gases in low dimensions. (author)

  12. Quasi-atoms

    International Nuclear Information System (INIS)

    Armbruster, P.

    1976-01-01

    The concept of a quasi-atom is discussed, and several experiments are described in which molecular or quasi-atomic transitions have been observed. X-ray spectra are shown for these experiments in which heavy ion projectiles were incident on various targets and the resultant combined system behaved as a quasi-atom. This rapidly developing field has already given new insight into atomic collision phenomena. (P.J.S.)

  13. 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

  14. 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.

  15. Revisiting peace and conflict studies

    DEFF Research Database (Denmark)

    Hagmann, Tobias

    2014-01-01

    dominant geopolitics it initially set out to criticise. Secondly, I will map – undoubtedly in cursory and incomplete fashion – the scholarly communities and literatures dealing with questions of peace and conflict. Rather than a literature review or an attempt at synthesis, my purpose is to highlight...... the broad variety of existing units of analysis, motivations, theories and methodologies of peace and conflict studies. Thirdly, I will propose a number of suggestions for a research attitude that, in absence of a better word, I subsume under the heading of ‘critical peace and conflict research’, striving...... to understand peace and conflict as concomitantly subjective and objective, as critique and hegemony, as normative and value-free, as local and global....

  16. Compound verbs in English revisited

    Directory of Open Access Journals (Sweden)

    Alexandra Bagasheva

    2011-05-01

    Full Text Available Compound verbs (CVs raise a number of puzzling questions concerning their classification, their word formation properties, their basic onomasiological function and their transitory status between “relations” and “conceptual-cores”. Using the constructionist framework in the context of a usage-based network model of language, the paper develops a proposal for the classification of CVs and an account of the semantics of word formation niches of CVs created by analogy, which yield unified semantic analyses. A hypothesis is formulated concerning the acategorial nature of CV internal constituents, which naturally accommodates the proposed classification and word formation niche analyses. A hypothesis is formulated in this context concerning the intermediary status of CVs as language-cognition interface units collapsing the “relation-conceptual core” distinction. Conclusions are drawn relating to the transitory nature of most CVs as nonce creations performing a special function in communicative interaction.

  17. Compound verbs in English revisited

    Directory of Open Access Journals (Sweden)

    Alexandra Bagasheva

    2011-01-01

    Full Text Available Compound verbs (CVs raise a number of puzzling questions concerning their classification, their word formation properties, their basic onomasiological function and their transitory status between “relations” and “conceptual-cores”. Using the constructionist framework in the context of a usage-based network model of language, the paper develops a proposal for the classification of CVs and an account of the semantics of word formation niches of CVs created by analogy, which yield unified semantic analyses. A hypothesis is formulated concerning the acategorial nature of CV internal constituents, which naturally accommodates the proposed classification and word formation niche analyses. A hypothesis is formulated in this context concerning the intermediary status of CVs as language-cognition interface units collapsing the “relation-conceptual core” distinction. Conclusions are drawn relating to the transitory nature of most CVs as nonce creations performing a special function in communicative interaction.

  18. 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)

  19. Electron scattering by trapped fermionic atoms

    International Nuclear Information System (INIS)

    Wang Haijun; Jhe, Wonho

    2002-01-01

    Considering the Fermi gases of alkali-metal atoms that are trapped in a harmonic potential, we study theoretically the elastic and inelastic scattering of the electrons by the trapped Fermi atoms and present the corresponding differential cross sections. We also obtain the stopping power for the cases that the electronic state as well as the center-of-mass state are excited both separately and simultaneously. It is shown that the elastic scattering process is no longer coherent in contrast to the electron scattering by the atomic Bose-Einstein condensate (BEC). For the inelastic scattering process, on the other hand, the differential cross section is found to be proportional to the 2/3 power of the number of the trapped atoms. In particular, the trapped fermionic atoms display the effect of ''Fermi surface,'' that is, only the energy levels near the Fermi energy have dominant contributions to the scattering process. Moreover, it is found that the stopping power scales as the 7/6 power of the atomic number. These results are fundamentally different from those of the electron scattering by the atomic BEC, mainly due to the different statistics obeyed by the trapped atomic systems

  20. Newton's law of cooling revisited

    International Nuclear Information System (INIS)

    Vollmer, M

    2009-01-01

    The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer from any object to its surrounding is not only due to conduction and convection but also due to radiation. The latter does not vary linearly with temperature difference, which leads to deviations from Newton's law. This paper presents a theoretical analysis of the cooling of objects with a small Biot number. It is shown that Newton's law of cooling, i.e. simple exponential behaviour, is mostly valid if temperature differences are below a certain threshold which depends on the experimental conditions. For any larger temperature differences appreciable deviations occur which need the complete nonlinear treatment. This is demonstrated by results of some laboratory experiments which use IR imaging to measure surface temperatures of solid cooling objects with temperature differences of up to 300 K.

  1. Muon-catalyzed fusion revisited

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1984-12-15

    A negative muon can induce nuclear fusion in the reaction of deuteron and triton nuclei giving a helium nucleus, a neutron and an emerging negative muon. The muon forms a tightlybound deuteron-triton-muon molecule and fusion follows in about 10{sup -12}s. Then the muon is free again to induce further reactions. Thus the muon can serve as a catalyst for nuclear fusion, which can proceed without the need for the high temperatures which are needed in the confinement and inertial fusion schemes. At room temperature, up to 80 fusions per muon have recently been observed at the LAMPF machine at Los Alamos, and it is clear that this number can be exceeded. These and other results were presented at a summer Workshop on Muon-Catalyzed Fusion held in Jackson, Wyoming. Approximately fifty scientists attended from Austria, Canada, India, Italy, Japan, South Africa, West Germany, and the United States. The Workshop itself is symbolic of the revival of interest in this subject.

  2. The isotropic radio background revisited

    Energy Technology Data Exchange (ETDEWEB)

    Fornengo, Nicolao; Regis, Marco [Dipartimento di Fisica Teorica, Università di Torino, via P. Giuria 1, I–10125 Torino (Italy); Lineros, Roberto A. [Instituto de Física Corpuscular – CSIC/U. Valencia, Parc Científic, calle Catedrático José Beltrán, 2, E-46980 Paterna (Spain); Taoso, Marco, E-mail: fornengo@to.infn.it, E-mail: rlineros@ific.uv.es, E-mail: regis@to.infn.it, E-mail: taoso@cea.fr [Institut de Physique Théorique, CEA/Saclay, F-91191 Gif-sur-Yvette Cédex (France)

    2014-04-01

    We present an extensive analysis on the determination of the isotropic radio background. We consider six different radio maps, ranging from 22 MHz to 2.3 GHz and covering a large fraction of the sky. The large scale emission is modeled as a linear combination of an isotropic component plus the Galactic synchrotron radiation and thermal bremsstrahlung. Point-like and extended sources are either masked or accounted for by means of a template. We find a robust estimate of the isotropic radio background, with limited scatter among different Galactic models. The level of the isotropic background lies significantly above the contribution obtained by integrating the number counts of observed extragalactic sources. Since the isotropic component dominates at high latitudes, thus making the profile of the total emission flat, a Galactic origin for such excess appears unlikely. We conclude that, unless a systematic offset is present in the maps, and provided that our current understanding of the Galactic synchrotron emission is reasonable, extragalactic sources well below the current experimental threshold seem to account for the majority of the brightness of the extragalactic radio sky.

  3. The isotropic radio background revisited

    International Nuclear Information System (INIS)

    Fornengo, Nicolao; Regis, Marco; Lineros, Roberto A.; Taoso, Marco

    2014-01-01

    We present an extensive analysis on the determination of the isotropic radio background. We consider six different radio maps, ranging from 22 MHz to 2.3 GHz and covering a large fraction of the sky. The large scale emission is modeled as a linear combination of an isotropic component plus the Galactic synchrotron radiation and thermal bremsstrahlung. Point-like and extended sources are either masked or accounted for by means of a template. We find a robust estimate of the isotropic radio background, with limited scatter among different Galactic models. The level of the isotropic background lies significantly above the contribution obtained by integrating the number counts of observed extragalactic sources. Since the isotropic component dominates at high latitudes, thus making the profile of the total emission flat, a Galactic origin for such excess appears unlikely. We conclude that, unless a systematic offset is present in the maps, and provided that our current understanding of the Galactic synchrotron emission is reasonable, extragalactic sources well below the current experimental threshold seem to account for the majority of the brightness of the extragalactic radio sky

  4. Big-bang nucleosynthesis revisited

    Science.gov (United States)

    Olive, Keith A.; Schramm, David N.; Steigman, Gary; Walker, Terry P.

    1989-01-01

    The homogeneous big-bang nucleosynthesis yields of D, He-3, He-4, and Li-7 are computed taking into account recent measurements of the neutron mean-life as well as updates of several nuclear reaction rates which primarily affect the production of Li-7. The extraction of primordial abundances from observation and the likelihood that the primordial mass fraction of He-4, Y(sub p) is less than or equal to 0.24 are discussed. Using the primordial abundances of D + He-3 and Li-7 we limit the baryon-to-photon ratio (eta in units of 10 exp -10) 2.6 less than or equal to eta(sub 10) less than or equal to 4.3; which we use to argue that baryons contribute between 0.02 and 0.11 to the critical energy density of the universe. An upper limit to Y(sub p) of 0.24 constrains the number of light neutrinos to N(sub nu) less than or equal to 3.4, in excellent agreement with the LEP and SLC collider results. We turn this argument around to show that the collider limit of 3 neutrino species can be used to bound the primordial abundance of He-4: 0.235 less than or equal to Y(sub p) less than or equal to 0.245.

  5. Revisiting convergence: A research note.

    Science.gov (United States)

    Clark, Rob

    2015-09-01

    A number of recent studies show that income inequality is declining between countries. In this research note, I question the significance of this trend by examining the role of initial conditions in producing convergence. An important (but neglected) property of inequality dynamics is the tendency for extreme distributions to become more moderate. When income disparities are large, the subsequent trend is biased toward convergence. Conversely, when initial conditions approach parity, divergence becomes the more likely long-term outcome. I apply this principle to trends in GDP PC across 127 countries during the 1980-2010 period. Using counterfactual analysis, I manipulate the initial level of inequality in GDP PC while holding constant each country's observed growth rate during the sample period. I find that the growth dynamics of GDP PC produce either convergence or divergence based simply on the initial distribution of income. The point of transition occurs at a moderate level of inequality, whether using population weights (Gini=.365) or not (Gini=.377). I conclude that the recent convergence observed in GDP PC is primarily a function of large income gaps between countries and would not have materialized at more moderate levels of initial inequality. By contrast, an examination of the pre-1950 period reveals divergent growth patterns that are not sensitive to initial conditions. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Post-Inflationary Gravitino Production Revisited

    CERN Document Server

    Ellis, John; Nanopoulos, Dimitri V.; Olive, Keith A.; Peloso, Marco

    2016-01-01

    We revisit gravitino production following inflation. As a first step, we review the standard calculation of gravitino production in the thermal plasma formed at the end of post-inflationary reheating when the inflaton has completely decayed. Next we consider gravitino production prior to the completion of reheating, assuming that the inflaton decay products thermalize instantaneously while they are still dilute. We then argue that instantaneous thermalization is in general a good approximation, and also show that the contribution of non-thermal gravitino production via the collisions of inflaton decay products prior to thermalization is relatively small. Our final estimate of the gravitino-to-entropy ratio is approximated well by a standard calculation of gravitino production in the post-inflationary thermal plasma assuming total instantaneous decay and thermalization at a time $t \\simeq 1.2/\\Gamma_\\phi$. Finally, in light of our calculations, we consider potential implications of upper limits on the gravitin...

  7. Revisiting R-invariant direct gauge mediation

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Cheng-Wei [Center for Mathematics and Theoretical Physics andDepartment of Physics, National Central University,Taoyuan, Taiwan 32001, R.O.C. (China); Institute of Physics, Academia Sinica,Taipei, Taiwan 11529, R.O.C. (China); Physics Division, National Center for Theoretical Sciences,Hsinchu, Taiwan 30013, R.O.C. (China); Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Harigaya, Keisuke [Department of Physics, University of California,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States); ICRR, University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Ibe, Masahiro [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); ICRR, University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Yanagida, Tsutomu T. [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan)

    2016-03-21

    We revisit a special model of gauge mediated supersymmetry breaking, the “R-invariant direct gauge mediation.” We pay particular attention to whether the model is consistent with the minimal model of the μ-term, i.e., a simple mass term of the Higgs doublets in the superpotential. Although the incompatibility is highlighted in view of the current experimental constraints on the superparticle masses and the observed Higgs boson mass, the minimal μ-term can be consistent with the R-invariant gauge mediation model via a careful choice of model parameters. We derive an upper limit on the gluino mass from the observed Higgs boson mass. We also discuss whether the model can explain the 3σ excess of the Z+jets+E{sub T}{sup miss} events reported by the ATLAS collaboration.

  8. The Faraday effect revisited General theory

    CERN Document Server

    Cornean, H D; Pedersen, T G

    2005-01-01

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse conductivity can be explicitly computed and coincides with the classical result. In the general case, using magnetic perturbation theory, the conductivity tensor is expanded in powers of the strength of the magnetic field $B$. Then the linear term in $B$ of this expansion is written down in terms of the zero magnetic field Green function and the zero field current operator. In the periodic case, the linear term in $B$ of the conductivity tensor is expressed in terms of zero magnetic field Bloch functions and energies. No derivatives with respect to the quasimomentum appear and thereby all ambiguities are removed, in contrast to earlier work.

  9. Revisiting instanton corrections to the Konishi multiplet

    Energy Technology Data Exchange (ETDEWEB)

    Alday, Luis F. [Mathematical Institute, University of Oxford,Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG (United Kingdom); Korchemsky, Gregory P. [Institut de Physique Théorique, Université Paris Saclay, CNRS, CEA,F-91191 Gif-sur-Yvette (France)

    2016-12-01

    We revisit the calculation of instanton effects in correlation functions in N=4 SYM involving the Konishi operator and operators of twist two. Previous studies revealed that the scaling dimensions and the OPE coefficients of these operators do not receive instanton corrections in the semiclassical approximation. We go beyond this approximation and demonstrate that, while operators belonging to the same N=4 supermultiplet ought to have the same conformal data, the evaluation of quantum instanton corrections for one operator can be mapped into a semiclassical computation for another operator in the same supermultiplet. This observation allows us to compute explicitly the leading instanton correction to the scaling dimension of operators in the Konishi supermultiplet as well as to their structure constants in the OPE of two half-BPS scalar operators. We then use these results, together with crossing symmetry, to determine instanton corrections to scaling dimensions of twist-four operators with large spin.

  10. Revisiting kaon physics in general Z scenario

    Directory of Open Access Journals (Sweden)

    Motoi Endo

    2017-08-01

    Full Text Available New physics contributions to the Z penguin are revisited in the light of the recently-reported discrepancy of the direct CP violation in K→ππ. Interference effects between the standard model and new physics contributions to ΔS=2 observables are taken into account. Although the effects are overlooked in the literature, they make experimental bounds significantly severer. It is shown that the new physics contributions must be tuned to enhance B(KL→π0νν¯, if the discrepancy of the direct CP violation is explained with satisfying the experimental constraints. The branching ratio can be as large as 6×10−10 when the contributions are tuned at the 10% level.

  11. Sparse random matrices: The eigenvalue spectrum revisited

    International Nuclear Information System (INIS)

    Semerjian, Guilhem; Cugliandolo, Leticia F.

    2003-08-01

    We revisit the derivation of the density of states of sparse random matrices. We derive a recursion relation that allows one to compute the spectrum of the matrix of incidence for finite trees that determines completely the low concentration limit. Using the iterative scheme introduced by Biroli and Monasson [J. Phys. A 32, L255 (1999)] we find an approximate expression for the density of states expected to hold exactly in the opposite limit of large but finite concentration. The combination of the two methods yields a very simple geometric interpretation of the tails of the spectrum. We test the analytic results with numerical simulations and we suggest an indirect numerical method to explore the tails of the spectrum. (author)

  12. Neutrino dark energy. Revisiting the stability issue

    Energy Technology Data Exchange (ETDEWEB)

    Eggers Bjaelde, O.; Hannestad, S. [Aarhus Univ. (Denmark). Dept. of Physics and Astronomy; Brookfield, A.W. [Sheffield Univ. (United Kingdom). Dept. of Applied Mathematics and Dept. of Physics, Astro-Particle Theory and Cosmology Group; Van de Bruck, C. [Sheffield Univ. (United Kingdom). Dept. of Applied Mathematics, Astro-Particle Theory and Cosmology Group; Mota, D.F. [Heidelberg Univ. (Germany). Inst. fuer Theoretische Physik]|[Institute of Theoretical Astrophysics, Oslo (Norway); Schrempp, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Tocchini-Valentini, D. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics and Astronomy

    2007-05-15

    A coupling between a light scalar field and neutrinos has been widely discussed as a mechanism for linking (time varying) neutrino masses and the present energy density and equation of state of dark energy. However, it has been pointed out that the viability of this scenario in the non-relativistic neutrino regime is threatened by the strong growth of hydrodynamic perturbations associated with a negative adiabatic sound speed squared. In this paper we revisit the stability issue in the framework of linear perturbation theory in a model independent way. The criterion for the stability of a model is translated into a constraint on the scalar-neutrino coupling, which depends on the ratio of the energy densities in neutrinos and cold dark matter. We illustrate our results by providing meaningful examples both for stable and unstable models. (orig.)

  13. Re-visiting the electrophysiology of language.

    Science.gov (United States)

    Obleser, Jonas

    2015-09-01

    This editorial accompanies a special issue of Brain and Language re-visiting old themes and new leads in the electrophysiology of language. The event-related potential (ERP) as a series of characteristic deflections ("components") over time and their distribution on the scalp has been exploited by speech and language researchers over decades to find support for diverse psycholinguistic models. Fortunately, methodological and statistical advances have allowed human neuroscience to move beyond some of the limitations imposed when looking at the ERP only. Most importantly, we currently witness a refined and refreshed look at "event-related" (in the literal sense) brain activity that relates itself more closely to the actual neurobiology of speech and language processes. It is this imminent change in handling and interpreting electrophysiological data of speech and language experiments that this special issue intends to capture. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. How does the Ambience of Cafe Affect the Revisit Intention Among its Patrons? A S on the Cafes in Ipoh, Perak

    Directory of Open Access Journals (Sweden)

    AbuThahir Sharmeela-Banu Syed

    2018-01-01

    Full Text Available Food service industry is growing rapidly as a result of the changing consumer lifestyle. The food service industry is highly competitive due to the increasing number of new entrants offering inventive food products and services. In order to be outstanding in such competitive industry, retailers nowadays opt to emphasize on their store environment. Past studies discovered that store environment stimulates emotions that significantly boost customer revisit intention. As a result, retailers attempt to differentiate their store by combining various environmental stimuli to create an attractive ambience that will in turn draw in the customers. Hence, this study attempts to investigate the impact of various café ambience factors on the patrons’ revisit intention. The patrons of cafes in Ipoh, Perak were selected using purposive sampling technique to be the respondents of this study. 250 questionnaires were collected and Partial Least Square technique was used to analyse the data collected. Findings show that all the five factors of café ambience namely lighting, music, decoration, cleanliness and layouts were significantly influencing the patrons’ revisit intention. Of these five factors, lighting was most influential while music was the least influential in affecting the patrons’ revisit intention. Accordingly, this study lists several recommendations for practitioners and academics with regards to the store environment and its impact on the repurchase intention.

  15. Refined Betz limit for rotors with a finite number of blades

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær

    2008-01-01

    The criterion of Betz for optimum rotors with a finite number of blades is revisited and used to determine the performance of wind turbines. The Betz criterion states that ideal efficiency is obtained when the distribution of circulation along the blade produces a rigidly helicoid wake that moves...... model is consistent with the general momentum theory and enables for the first time to determine the theoretical maximum efficiency of rotors with an arbitrary number of blades....

  16. Positronium-alkali atom scattering at medium energies

    International Nuclear Information System (INIS)

    Chakraborty, Ajoy; Basu, Arindam; Sarkar, Nirmal K; Sinha, Prabal K

    2004-01-01

    We investigate the scattering of orthopositronium (o-Ps) atom off different atomic alkali targets (Na to Cs) at low and medium energies (up to 120 eV). Projectile-elastic and target-elastic close-coupling models have been employed to investigate the systems in addition to the static-exchange model. Elastic, excitation and total cross sections have been reported for all four systems. The magnitude of the alkali excitation cross section increases with increasing atomic number of the target atom while the position of the peak value shifts towards lower incident energies. The magnitudes of the Ps excitation and ionization cross sections increase steadily with atomic number with no change in the peak position. The reported results show regular behaviour with increasing atomic number of the target atom. Scattering parameters for the Ps-Rb and Ps-Cs systems are being reported for the first time

  17. A Cooperative Search and Coverage Algorithm with Controllable Revisit and Connectivity Maintenance for Multiple Unmanned Aerial Vehicles

    Directory of Open Access Journals (Sweden)

    Zhong Liu

    2018-05-01

    Full Text Available In this paper, we mainly study a cooperative search and coverage algorithm for a given bounded rectangle region, which contains several unknown stationary targets, by a team of unmanned aerial vehicles (UAVs with non-ideal sensors and limited communication ranges. Our goal is to minimize the search time, while gathering more information about the environment and finding more targets. For this purpose, a novel cooperative search and coverage algorithm with controllable revisit mechanism is presented. Firstly, as the representation of the environment, the cognitive maps that included the target probability map (TPM, the uncertain map (UM, and the digital pheromone map (DPM are constituted. We also design a distributed update and fusion scheme for the cognitive map. This update and fusion scheme can guarantee that each one of the cognitive maps converges to the same one, which reflects the targets’ true existence or absence in each cell of the search region. Secondly, we develop a controllable revisit mechanism based on the DPM. This mechanism can concentrate the UAVs to revisit sub-areas that have a large target probability or high uncertainty. Thirdly, in the frame of distributed receding horizon optimizing, a path planning algorithm for the multi-UAVs cooperative search and coverage is designed. In the path planning algorithm, the movement of the UAVs is restricted by the potential fields to meet the requirements of avoiding collision and maintaining connectivity constraints. Moreover, using the minimum spanning tree (MST topology optimization strategy, we can obtain a tradeoff between the search coverage enhancement and the connectivity maintenance. The feasibility of the proposed algorithm is demonstrated by comparison simulations by way of analyzing the effects of the controllable revisit mechanism and the connectivity maintenance scheme. The Monte Carlo method is employed to validate the influence of the number of UAVs, the sensing radius

  18. Atomic Energy Research benchmark activity

    International Nuclear Information System (INIS)

    Makai, M.

    1998-01-01

    The test problems utilized in the validation and verification process of computer programs in Atomic Energie Research are collected into one bunch. This is the first step towards issuing a volume in which tests for VVER are collected, along with reference solutions and a number of solutions. The benchmarks do not include the ZR-6 experiments because they have been published along with a number of comparisons in the Final reports of TIC. The present collection focuses on operational and mathematical benchmarks which cover almost the entire range of reaktor calculation. (Author)

  19. Atoms for peace plus fifty

    International Nuclear Information System (INIS)

    Eisenhower, S.

    2003-01-01

    One of Dwight Eisenhower's most significant political legacies stemmed from his management of the nuclear question. Five decades after Eisenhower's 'Atoms for Peace' speech before the United Nations, the nuclear dilemma persists but the world is a different, and I would submit, a better place today than it might have been had that vision not been articulated, or its proposals not advanced. The 'Atoms for Peace' speech had a number of objectives, but it is over arching goal was to propose a set of ideas, a nuclear strategy, which would call on the Soviets to cooperate internationally for the betterment of mankind. This would reengage the Soviets in discussions on nuclear matters at a time when arms control talks had stalled, but it would also offer hope, and a practical set of ideas, to the developing world. 'Atoms for Peace' spawned many developments, including the establishment of the International Atomic Energy Agency, and eventually the Nuclear Non-Proliferation Treaty. While 'Atoms for Peace', as well as the institutions it created, has come under fire in recent years, it is hard to imagine what the world would have been like without it. Largely through the international Atomic Energy Agency, nations around the world have participated in research and development programs, including the use of nuclear energy in important civilian applications. Nuclear electric power accounts for nearly one-fifth of the world's electricity - reducing global tensions by replacing oil in many applications, and providing much of the world's electricity that is generated without the release of greenhouse gases or other destructive emissions. Many other nuclear and radiation-related technologies, especially radiopharmaceuticals and medical advances involving radiation, have resulted in large part from research spawned by 'Atoms for Peace'. Millions of lives have been saved in the process. While the 'nuclear dilemma' remains a challenge almost as complex as it was fifty years ago, the

  20. 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

  1. 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

  2. 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

  3. 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...

  4. Effect of temperature on atom-atom collision chain length in metals

    International Nuclear Information System (INIS)

    Makarov, A.A.; Demkin, N.A.; Lyashchenko, B.G.

    1981-01-01

    Focused atom-atom collision chain lengths are calculated for fcc-crystals with account of thermal oscillations. The model of solid spheres with the Born-Merier potential has been used in the calculations. The dependence of chain lengths on the temperature, energy and movement direction of the first chain atom for Cu, Au, Ag, Pb, Ni is considered. The plot presented shows that the chain lengths strongly decrease with temperature growth, for example, for the gold at T=100 K the chain length equals up to 37 interatomic spacings, whereas at T=1000 K their length decreases down to 5 interatomic distances. The dependence of the energy loss by the chain atoms on the atom number in the chain is obtained in a wide range of crystal temperature and the primary chain atom energy [ru

  5. Quantum phase transitions in atomic nuclei

    International Nuclear Information System (INIS)

    Zamfir, N.V.

    2005-01-01

    Studies of quantum phase transitions in mesoscopic systems and applications to atomic nuclei are presented. Analysis in terms of the Interacting Boson Model shows that the main features persist even for moderate number of particles. Experimental evidence in rare-earth nuclei is discussed. New order and control parameters for systems with the same number of particles are proposed. (author)

  6. Atoms, molecules and optical physics 1. Atoms and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hertel, Ingolf V.; Schulz, Claus-Peter

    2015-09-01

    This is the first volume of textbooks on atomic, molecular and optical physics, aiming at a comprehensive presentation of this highly productive branch of modern physics as an indispensable basis for many areas in physics and chemistry as well as in state of the art bio- and material-sciences. It primarily addresses advanced students (including PhD students), but in a number of selected subject areas the reader is lead up to the frontiers of present research. Thus even the active scientist is addressed. This volume 1 provides the canonical knowledge in atomic physics together with basics of modern spectroscopy. Starting from the fundamentals of quantum physics, the reader is familiarized in well structured chapters step by step with the most important phenomena, models and measuring techniques. The emphasis is always on the experiment and its interpretation, while the necessary theory is introduced from this perspective in a compact and occasionally somewhat heuristic manner, easy to follow even for beginners.

  7. Metal atom oxidation laser

    International Nuclear Information System (INIS)

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-01-01

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides

  8. 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.

  9. Economical Atomic Layer Deposition

    Science.gov (United States)

    Wyman, Richard; Davis, Robert; Linford, Matthew

    2010-10-01

    Atomic Layer Deposition is a self limiting deposition process that can produce films at a user specified height. At BYU we have designed a low cost and automated atomic layer deposition system. We have used the system to deposit silicon dioxide at room temperature using silicon tetrachloride and tetramethyl orthosilicate. Basics of atomic layer deposition, the system set up, automation techniques and our system's characterization are discussed.

  10. 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)

  11. Deeply bound pionic atom

    International Nuclear Information System (INIS)

    Toki, Hiroshi; Yamazaki, Toshimitsu

    1989-01-01

    The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)

  12. Single atom oscillations

    International Nuclear Information System (INIS)

    Wiorkowski, P.; Walther, H.

    1990-01-01

    Modern methods of laser spectroscopy allow the study of single atoms or ions in an unperturbed environment. This has opened up interesting new experiments, among them the detailed study of radiation-atom coupling. In this paper, the following two experiments dealing with this problem are reviewed: the single-atom maser and the study of the resonance fluorescence of a single stored ion. The simplest and most fundamental system for studying radiation-matter coupling is a single two-level atom interacting with a single mode of an electromagnetic field in a cavity. This problem received a great deal of attention shortly after the maser was invented

  13. Electromagnetically Induced Transparency In Rydberg Atomic Medium

    Science.gov (United States)

    Deng, Li; Cong, Lu; Chen, Ai-Xi

    2018-03-01

    Due to possessing big principal quantum number, Rydberg atom has some unique properties, for example: its radiative lifetime is long, dipole moment is large, and interaction between atoms is strong and so on. These properties make one pay attention to Rydberg atoms. In this paper we investigate the effects of Rydberg dipole-dipole interactions on electromagnetically induced transparency (EIT) schemes and group velocity in three-level systems of ladder type, which provides theoretical foundation for exploring the linear and nonlinear characteristics of light in a Rydberg electromagnetically-induced-transparency medium.

  14. Dynamics in atomic signaling games

    KAUST Repository

    Fox, Michael J.

    2015-04-08

    We study an atomic signaling game under stochastic evolutionary dynamics. There are a finite number of players who repeatedly update from a finite number of available languages/signaling strategies. Players imitate the most fit agents with high probability or mutate with low probability. We analyze the long-run distribution of states and show that, for sufficiently small mutation probability, its support is limited to efficient communication systems. We find that this behavior is insensitive to the particular choice of evolutionary dynamic, a property that is due to the game having a potential structure with a potential function corresponding to average fitness. Consequently, the model supports conclusions similar to those found in the literature on language competition. That is, we show that efficient languages eventually predominate the society while reproducing the empirical phenomenon of linguistic drift. The emergence of efficiency in the atomic case can be contrasted with results for non-atomic signaling games that establish the non-negligible possibility of convergence, under replicator dynamics, to states of unbounded efficiency loss.

  15. Dynamics in atomic signaling games

    KAUST Repository

    Fox, Michael J.; Touri, Behrouz; Shamma, Jeff S.

    2015-01-01

    We study an atomic signaling game under stochastic evolutionary dynamics. There are a finite number of players who repeatedly update from a finite number of available languages/signaling strategies. Players imitate the most fit agents with high probability or mutate with low probability. We analyze the long-run distribution of states and show that, for sufficiently small mutation probability, its support is limited to efficient communication systems. We find that this behavior is insensitive to the particular choice of evolutionary dynamic, a property that is due to the game having a potential structure with a potential function corresponding to average fitness. Consequently, the model supports conclusions similar to those found in the literature on language competition. That is, we show that efficient languages eventually predominate the society while reproducing the empirical phenomenon of linguistic drift. The emergence of efficiency in the atomic case can be contrasted with results for non-atomic signaling games that establish the non-negligible possibility of convergence, under replicator dynamics, to states of unbounded efficiency loss.

  16. Stop Band Gap in Periodic Layers of Confined Atomic Vapor/Dielectric Medium

    International Nuclear Information System (INIS)

    Li Yuan-Yuan; Li Li; Lu Yi-Xin; Zhang Yan-Peng; Xu Ke-Wei

    2013-01-01

    A stop band gap is predicted in periodic layers of a confined atomic vapor/dielectric medium. Reflection and transmission profile of the layers over the band gap can be dramatically modified by the confined atoms and the number of layer periods. These gap and line features can be ascribed to the enhanced contribution of slow atoms induced by atom-wall collision, transient behavior of atom-light interaction and Fabry—Pérot effects in a thermal confined atomic system

  17. From heavy ions to exotic atoms

    OpenAIRE

    Indelicato, Paul; Trassinelli, Martino

    2005-01-01

    We review a number of experiments and theoretical calculations on heavy ions and exotic atoms, which aim at providing informations on fundamental interactions. Among those are propositions of experiments for parity violation measurements in heavy ions and high-precision mesurements of He-like transition energies in highly charged ions. We also describe recent experiments on pionic atoms, that make use of highly-charged ion transitions to obtain accurate measurements of strong interaction shif...

  18. Atomic energy levels and Grotrian diagrams

    CERN Document Server

    Bashkin, Stanley

    1975-01-01

    Atomic Energy Levels and Grotrian Diagrams, Volume I: Hydrogen I - Phosphorus XV presents diagrams of various elements that show their energy level and electronic transitions. The book covers the first 15 elements according to their atomic number. The text will be of great use to researchers and practitioners of fields such as astrophysics that requires pictorial representation of the energy levels and electronic transitions of elements.

  19. Atoms in astrophysics

    CERN Document Server

    Eissner, W; Hummer, D; Percival, I

    1983-01-01

    It is hard to appreciate but nevertheless true that Michael John Seaton, known internationally for the enthusiasm and skill with which he pursues his research in atomic physics and astrophysics, will be sixty years old on the 16th of January 1983. To mark this occasion some of his colleagues and former students have prepared this volume. It contains articles that de­ scribe some of the topics that have attracted his attention since he first started his research work at University College London so many years ago. Seaton's association with University College London has now stretched over a period of some 37 years, first as an undergraduate student, then as a research student, and then, successively, as Assistant Lecturer, Lecturer, Reader, and Professor. Seaton arrived at University College London in 1946 to become an undergraduate in the Physics Department, having just left the Royal Air Force in which he had served as a navigator in the Pathfinder Force of Bomber Command. There are a number of stories of ho...

  20. (e, 2e) triple differential cross sections of Ca atoms at low energies

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, G; Patidar, Vinod; Sud, K K [Department of Basic Sciences, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur 313 601 (India)], E-mail: g_vpurohit@yahoo.com, E-mail: ghanshyam.purohit@spsu.ac.in

    2009-12-15

    Recently, several theoretical studies (Hitawala et al 2008 J. Phys. B: At. Mol. Opt. Phys. 41 035205; Khajuria and Deshmukh 2008 Phys. Rev. A 78 024702; Chauhan et al 2005 Phys. Rev. A 71 032708) have been reported to analyze the measurements of triple differential cross section (TDCS) for (e, 2e) processes on Ca (4s{sup 2}) atom in coplanar geometry (Murray 2005 Phys. Rev. A 72 062711). In this paper, the (e, 2e) TDCS of the Ca atom has been revisited with the inclusion of correlation-polarization potential and post-collision interaction in the distorted wave Born approximation formalism. We note that the present attempt significantly improves the understanding of (e, 2e) processes at low energies on Ca atom. Still there are several discrepancies between the experimental and theoretical results that require more theoretical attempts to explain them properly.

  1. 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.

  2. Atoms stories; Histoire d`atomes

    Energy Technology Data Exchange (ETDEWEB)

    Radvanyi, P; Bordry, M [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France)

    1988-12-31

    Physicists from different countries told each evening during one learning week, to an audience of young people, some great discoveries in evoking the difficulties and problems to which the researchers were confronted. From Antiquity to a more recent history, it is a succession of atoms stories. (N.C.)

  3. Low energy atom-atom collisions

    International Nuclear Information System (INIS)

    Child, M.S.

    1980-01-01

    The semiclassical theory of atom-atom potential scattering and of low energy inelastic atom-atom scattering is reviewed. Particular attention is given to the origin and interpretation of rainbow structure, diffraction oscillations and exchange oscillations in the potential scattering differential cross-section, and to the glory structure and symmetry oscillations in the integral cross-section. Available methods for direct inversion of the cross-section data to recover the potential are reviewed in some detail. The theory of non-adiabatic transitions is introduced by a short discussion of interaction mechanisms and of diabetic and adiabatic representations. Analytical S matrix elements are presented for two state curve-crossing (Landau-Zener-Stuckelberg), Demkov and Nikitin models. The relation between Stuckelberg oscillations in the S matrix and in the differential cross-section is discussed in terms of interference between trajectories belonging to two different classical deflection functions. The energy dependences of the inelastic integral cross-section for curve-crossing and Demkov type transitions are also discussed. Finally the theory is reviewed in relation to a recent close-coupled study of fine structure transitions in F( 2 P) + Xe( 2 S) scattering

  4. Quantum chaos in atom optics

    International Nuclear Information System (INIS)

    D'Arcy, Michael Brendan

    2002-01-01

    This thesis presents an account of experimental and numerical investigations of two quantum systems whose respective classical analogues are chaotic. These are the δ-kicked rotor, a paradigm in classical chaos theory, and the novel δ-kicked accelerator, created by application of a constant external acceleration or torque to the rotor. The experimental realisation of these systems has been achieved by the exposure of laser-cooled caesium atoms to approximate δ-kicks from a pulsed, high-intensity, vertical standing wave of laser light. Gravity's effect on the atoms can be controlled by appropriate shifting of the profile of the standing wave. Numerical simulations of the systems are based on a diffractive model of the potential's effect. Each system's dynamics are characterised by the final form of the momentum distribution and the dependence of the atoms' mean kinetic energy on the number and time period of the δ-kicks. The phenomena of dynamical localisation and quantum resonances in the δ-kicked rotor, which have no counterparts in the system's classical analogue, are observed and investigated. Similar experiments on the δ-kicked accelerator reveal the striking phenomenon of the quantum accelerator mode, in which a large momentum is transferred to a substantial fraction of the atomic ensemble. This feature, absent in the system's classical analogue, is characterised and an analytic explanation is presented. The effect on each quantum system of decoherence, introduced through spontaneous emission in the atoms, is examined and comparison is made with the results of classical simulations. While having little effect on the classical systems, the level of decoherence used is found to degrade quantum signatures of behaviour. Classical-like behaviour is, to some extent, restored, although significant quantum features remain. Possible applications of the quantum accelerator mode are discussed. These include use as a tool in atom optics and interferometry, a

  5. 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.

  6. 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

  7. mu. -nucleon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Dobretsov, Yu; Dolgoshein, B; Kirillov-Ugryumov, V

    1980-12-01

    The properties and formation are described of ..mu..-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ..mu..-nucleon atoms is shown. The prospects of their use are indicated.

  8. μ-nucleon atoms

    International Nuclear Information System (INIS)

    Dobretsov, Yu.; Dolgoshejn, B.; Kirillov-Ugryumov, V.

    1980-01-01

    The properties and formation are described of μ-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of μ-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)

  9. 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.

  10. Atom lithography of Fe

    NARCIS (Netherlands)

    Sligte, te E.; Smeets, B.; van der Stam, K.M.R.; Herfst, R.W.; Straten, van der P.; Beijerinck, H.C.W.; Leeuwen, van K.A.H.

    2004-01-01

    Direct write atom lithography is a technique in which nearly resonant light is used to pattern an atom beam. Nanostructures are formed when the patterned beam falls onto a substrate. We have applied this lithography scheme to a ferromagnetic element, using a 372 nm laser light standing wave to

  11. 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.

  12. 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…

  13. Atom electron scattering

    International Nuclear Information System (INIS)

    Santoso, B.

    1976-01-01

    Green Lippmann-Schwinger functions operator representations, derivation of perturbation method using Green function and atom electron scattering, are discussed. It is concluded that by using complex coordinate places where resonances occur, can be accurately identified. The resonance can be processed further for practical purposes, for example for the separation of atom. (RUW)

  14. Atomic energy for progress

    International Nuclear Information System (INIS)

    1974-01-01

    The film discusses the functions and activities of the Philippine Atomic Energy Commission. Shown are the applications of atomic energy in research, agriculture, engineering, industry and medicine, as well as the construction of the research reactor and its inauguration by President Marcos

  15. 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.)

  16. Isotopes and atomic weights

    International Nuclear Information System (INIS)

    Zhang Qinglian

    1990-01-01

    A review of the chemical and mass spectrometric methods of determining the atomic weights of elements is presented. A, special discussion is devoted to the calibration of the mass spectrometer with highly enriched isotopes. It is illustrated by the recent work on europium. How to choose the candidate element for new atomic weight determination forms the last section of the article

  17. Revisiting System Paradigms from the Viewpoint of Manufacturing Sustainability

    Directory of Open Access Journals (Sweden)

    Zhuming Bi

    2011-08-01

    Full Text Available A system paradigm is an abstract representation of system; it includes system architecture used to determine the types and numbers of components and their relations in the system. The design of system paradigm relies on customers’ requirements and the characteristics of the manufacturing environment. Many system paradigms and design guidelines have been proposed for a variety of customers’ needs including functions, cost, quality, personalization, and lead time of products. However, the consideration of sustainability becomes essential to today’s manufacturing systems; a new challenge is how to evolve existing paradigms to accommodate the requirements of sustainability. In contrast to ample research activities on system paradigms in past decades, recent studies on system paradigms have been restricted, partially due to unclear research directions. Limited works can be found on conceiving new manufacturing system paradigms from the perspective of sustainability; most of the related literature concerns the new requirements of sustainability. The objectives of this work are (i to examine the requirements of manufacturing systems in a wider scope; (ii to revisit existing paradigms to clarify their limitations and bottlenecks; and eventually (iii to identify some research directions, which will lead to a solution of sustainable manufacturing. To achieve these objectives, firstly, a brief description of today’s manufacturing environment is provided. Secondly, the requirements of sustainability are discussed, and the relevant researches on system sustainability are surveyed. Thirdly, the reconfigurable system paradigm is focused, and the gaps between a reconfigurable manufacturing system and a sustainable manufacturing system are discussed. Finally, the future endeavors towards to the next-generation manufacturing system paradigms are discussed.

  18. LARGE-SCALE FILAMENTARY STRUCTURES AROUND THE VIRGO CLUSTER REVISITED

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Suk; Rey, Soo-Chang; Lee, Youngdae; Lee, Woong; Chung, Jiwon [Department of Astronomy and Space Science, Chungnam National University, 99 Daehak-ro, Daejeon 305-764 (Korea, Republic of); Bureau, Martin [Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Yoon, Hyein; Chung, Aeree [Department of Astronomy and Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of); Jerjen, Helmut [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Lisker, Thorsten [Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstraße 12-14, D-69120 Heidelberg (Germany); Jeong, Hyunjin; Sung, Eon-Chang, E-mail: screy@cnu.ac.kr, E-mail: star4citizen@kasi.re.kr [Korea Astronomy and Space Science institute, 776 Daedeokdae-ro, Daejeon 305-348 (Korea, Republic of)

    2016-12-20

    We revisit the filamentary structures of galaxies around the Virgo cluster, exploiting a larger data set, based on the HyperLeda database, than previous studies. In particular, this includes a large number of low-luminosity galaxies, resulting in better sampled individual structures. We confirm seven known structures in the distance range 4  h {sup −1} Mpc < SGY < 16  h {sup −1} Mpc, now identified as filaments, where SGY is the axis of the supergalactic coordinate system roughly along the line of sight. The Hubble diagram of the filament galaxies suggests they are infalling toward the main body of the Virgo cluster. We propose that the collinear distribution of giant elliptical galaxies along the fundamental axis of the Virgo cluster is smoothly connected to two of these filaments (Leo II A and B). Behind the Virgo cluster (16  h {sup −1} Mpc < SGY < 27  h {sup −1} Mpc), we also identify a new filament elongated toward the NGC 5353/4 group (“NGC 5353/4 filament”) and confirm a sheet that includes galaxies from the W and M clouds of the Virgo cluster (“W–M sheet”). In the Hubble diagram, the NGC 5353/4 filament galaxies show infall toward the NGC 5353/4 group, whereas the W–M sheet galaxies do not show hints of gravitational influence from the Virgo cluster. The filamentary structures identified can now be used to better understand the generic role of filaments in the build-up of galaxy clusters at z  ≈ 0.

  19. Dopant atoms as quantum components in silicon nanoscale devices

    Science.gov (United States)

    Zhao, Xiaosong; Han, Weihua; Wang, Hao; Ma, Liuhong; Li, Xiaoming; Zhang, Wang; Yan, Wei; Yang, Fuhua

    2018-06-01

    Recent progress in nanoscale fabrication allows many fundamental studies of the few dopant atoms in various semiconductor nanostructures. Since the size of nanoscale devices has touched the limit of the nature, a single dopant atom may dominate the performance of the device. Besides, the quantum computing considered as a future choice beyond Moore's law also utilizes dopant atoms as functional units. Therefore, the dopant atoms will play a significant role in the future novel nanoscale devices. This review focuses on the study of few dopant atoms as quantum components in silicon nanoscale device. The control of the number of dopant atoms and unique quantum transport characteristics induced by dopant atoms are presented. It can be predicted that the development of nanoelectronics based on dopant atoms will pave the way for new possibilities in quantum electronics. Project supported by National Key R&D Program of China (No. 2016YFA0200503).

  20. 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...

  1. 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)

  2. Laser trapping of 21Na atoms

    International Nuclear Information System (INIS)

    Lu, Zheng-Tian.

    1994-09-01

    This thesis describes an experiment in which about four thousand radioactive 21 Na (t l/2 = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped 21 Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of 21 Na → 21 Ne + Β + + v e , which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, 21 Na atoms were produced by bombarding 24 Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The 21 Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined

  3. Pair Production Constraints on Superluminal Neutrinos Revisited

    International Nuclear Information System (INIS)

    Brodsky, Stanley

    2012-01-01

    We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p 2 can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

  4. Carbon emission from global hydroelectric reservoirs revisited.

    Science.gov (United States)

    Li, Siyue; Zhang, Quanfa

    2014-12-01

    Substantial greenhouse gas (GHG) emissions from hydropower reservoirs have been of great concerns recently, yet the significant carbon emitters of drawdown area and reservoir downstream (including spillways and turbines as well as river reaches below dams) have not been included in global carbon budget. Here, we revisit GHG emission from hydropower reservoirs by considering reservoir surface area, drawdown zone and reservoir downstream. Our estimates demonstrate around 301.3 Tg carbon dioxide (CO2)/year and 18.7 Tg methane (CH4)/year from global hydroelectric reservoirs, which are much higher than recent observations. The sum of drawdown and downstream emission, which is generally overlooked, represents 42 % CO2 and 67 % CH4 of the total emissions from hydropower reservoirs. Accordingly, the global average emissions from hydropower are estimated to be 92 g CO2/kWh and 5.7 g CH4/kWh. Nonetheless, global hydroelectricity could currently reduce approximate 2,351 Tg CO2eq/year with respect to fuel fossil plant alternative. The new findings show a substantial revision of carbon emission from the global hydropower reservoirs.

  5. The drive revisited: Mastery and satisfaction.

    Science.gov (United States)

    Denis, Paul

    2016-06-01

    Starting from the theory of the libido and the notions of the experience of satisfaction and the drive for mastery introduced by Freud, the author revisits the notion of the drive by proposing the following model: the drive takes shape in the combination of two currents of libidinal cathexis, one which takes the paths of the 'apparatus for obtaining mastery' (the sense-organs, motricity, etc.) and strives to appropriate the object, and the other which cathects the erotogenic zones and the experience of satisfaction that is experienced through stimulation in contact with the object. The result of this combination of cathexes constitutes a 'representation', the subsequent evocation of which makes it possible to tolerate for a certain period of time the absence of a satisfying object. On the basis of this conception, the author distinguishes the representations proper, vehicles of satisfaction, from imagos and traumatic images which give rise to excitation that does not link up with the paths taken by the drives. This model makes it possible to conciliate the points of view of the advocates of 'object-seeking' and of those who give precedence to the search for pleasure, and, further, to renew our understanding of object-relations, which can then be approached from the angle of their relations to infantile sexuality. Destructiveness is considered in terms of "mastery madness" and not in terms of the late Freudian hypothesis of the death drive. Copyright © 2015 Institute of Psychoanalysis.

  6. Revisiting the argument from fetal potential

    Directory of Open Access Journals (Sweden)

    Manninen Bertha

    2007-05-01

    Full Text Available Abstract One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from potential. First, I will criticize the classical arguments proffered against the importance of fetal potential, specifically the arguments put forth by philosophers Peter Singer and David Boonin, by carefully unpacking the claims made in these arguments and illustrating why they are flawed. Secondly, I will maintain that fetal potential is morally relevant when it comes to the morality of abortion, but that it must be accorded a proper place in the argument. This proper place, however, cannot be found until we first answer a very important and complex question: we must first address the issue of personal identity, and when the fetus becomes the type of being who is relevantly identical to a future person. I will illustrate why the question of fetal potential can only be meaningfully addressed after we have first answered the question of personal identity and how it relates to the human fetus.

  7. THE CONCEPT OF REFERENCE CONDITION, REVISITED ...

    Science.gov (United States)

    Ecological assessments of aquatic ecosystems depend on the ability to compare current conditions against some expectation of how they could be in the absence of significant human disturbance. The concept of a ‘‘reference condition’’ is often used to describe the standard or benchmark against which current condition is compared. If assessments are to be conducted consistently, then a common understanding of the definitions and complications of reference condition is necessary. A 2006 paper (Stoddard et al., 2006, Ecological Applications 16:1267-1276) made an early attempt at codifying the reference condition concept; in this presentation we will revisit the points raised in that paper (and others) and examine how our thinking has changed in a little over 10 years.Among the issues to be discussed: (1) the “moving target” created when reference site data are used to set thresholds in large scale assessments; (2) natural vs. human disturbance and their effects on reference site distributions; (3) circularity and the use of biological data to assist in reference site identification; (4) using site-scale (in-stream or in-lake) measurements vs. landscape-level human activity to identify reference conditions. Ecological assessments of aquatic ecosystems depend on the ability to compare current conditions against some expectation of how they could be in the absence of significant human disturbance. The concept of a ‘‘reference condition’’ is often use

  8. The Super-GUT CMSSM Revisited

    CERN Document Server

    Ellis, John

    2016-01-01

    We revisit minimal supersymmetric SU(5) grand unification (GUT) models in which the soft supersymmetry-breaking parameters of the minimal supersymmetric Standard Model (MSSM) are universal at some input scale, $M_{in}$, above the supersymmetric gauge coupling unification scale, $M_{GUT}$. As in the constrained MSSM (CMSSM), we assume that the scalar masses and gaugino masses have common values, $m_0$ and $m_{1/2}$ respectively, at $M_{in}$, as do the trilinear soft supersymmetry-breaking parameters $A_0$. Going beyond previous studies of such a super-GUT CMSSM scenario, we explore the constraints imposed by the lower limit on the proton lifetime and the LHC measurement of the Higgs mass, $m_h$. We find regions of $m_0$, $m_{1/2}$, $A_0$ and the parameters of the SU(5) superpotential that are compatible with these and other phenomenological constraints such as the density of cold dark matter, which we assume to be provided by the lightest neutralino. Typically, these allowed regions appear for $m_0$ and $m_{1/...

  9. Searle's"Dualism Revisited"

    Energy Technology Data Exchange (ETDEWEB)

    P., Henry

    2008-11-20

    A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

  10. Early-Transition Output Decline Revisited

    Directory of Open Access Journals (Sweden)

    Crt Kostevc

    2016-05-01

    Full Text Available In this paper we revisit the issue of aggregate output decline that took place in the early transition period. We propose an alternative explanation of output decline that is applicable to Central- and Eastern-European countries. In the first part of the paper we develop a simple dynamic general equilibrium model that builds on work by Gomulka and Lane (2001. In particular, we consider price liberalization, interpreted as elimination of distortionary taxation, as a trigger of the output decline. We show that price liberalization in interaction with heterogeneous adjustment costs and non-employment benefits lead to aggregate output decline and surge in wage inequality. While these patterns are consistent with actual dynamics in CEE countries, this model cannot generate output decline in all sectors. Instead sectors that were initially taxed even exhibit output growth. Thus, in the second part we consider an alternative general equilibrium model with only one production sector and two types of labor and distortion in a form of wage compression during the socialist era. The trigger for labor mobility and consequently output decline is wage liberalization. Assuming heterogeneity of workers in terms of adjustment costs and non-employment benefits can explain output decline in all industries.

  11. Post-inflationary gravitino production revisited

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, John [Theoretical Particle Physics and Cosmology Group, Department of Physics, King' s College London, London WC2R 2LS (United Kingdom); Garcia, Marcos A.G.; Olive, Keith A. [William I. Fine Theoretical Physics Institute, School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Peloso, Marco, E-mail: john.ellis@cern.ch, E-mail: garciagarcia@physics.umn.edu, E-mail: dimitri@physics.tamu.edu, E-mail: olive@physics.umn.edu, E-mail: peloso@physics.umn.edu [School of Physics and Astronomy and Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

    2016-03-01

    We revisit gravitino production following inflation. As a first step, we review the standard calculation of gravitino production in the thermal plasma formed at the end of post-inflationary reheating when the inflaton has completely decayed. Next we consider gravitino production prior to the completion of reheating, assuming that the inflaton decay products thermalize instantaneously while they are still dilute. We then argue that instantaneous thermalization is in general a good approximation, and also show that the contribution of non-thermal gravitino production via the collisions of inflaton decay products prior to thermalization is relatively small. Our final estimate of the gravitino-to-entropy ratio is approximated well by a standard calculation of gravitino production in the post-inflationary thermal plasma assuming total instantaneous decay and thermalization at a time t ≅ 1.2/Γ{sub φ}. Finally, in light of our calculations, we consider potential implications of upper limits on the gravitino abundance for models of inflation, with particular attention to scenarios for inflaton decays in supersymmetric Starobinsky-like models.

  12. Pipe failure probability - the Thomas paper revisited

    International Nuclear Information System (INIS)

    Lydell, B.O.Y.

    2000-01-01

    Almost twenty years ago, in Volume 2 of Reliability Engineering (the predecessor of Reliability Engineering and System Safety), a paper by H. M. Thomas of Rolls Royce and Associates Ltd. presented a generalized approach to the estimation of piping and vessel failure probability. The 'Thomas-approach' used insights from actual failure statistics to calculate the probability of leakage and conditional probability of rupture given leakage. It was intended for practitioners without access to data on the service experience with piping and piping system components. This article revisits the Thomas paper by drawing on insights from development of a new database on piping failures in commercial nuclear power plants worldwide (SKI-PIPE). Partially sponsored by the Swedish Nuclear Power Inspectorate (SKI), the R and D leading up to this note was performed during 1994-1999. Motivated by data requirements of reliability analysis and probabilistic safety assessment (PSA), the new database supports statistical analysis of piping failure data. Against the background of this database development program, the article reviews the applicability of the 'Thomas approach' in applied risk and reliability analysis. It addresses the question whether a new and expanded database on the service experience with piping systems would alter the original piping reliability correlation as suggested by H. M. Thomas

  13. Revisit to diffraction anomalous fine structure

    International Nuclear Information System (INIS)

    Kawaguchi, T.; Fukuda, K.; Tokuda, K.; Shimada, K.; Ichitsubo, T.; Oishi, M.; Mizuki, J.; Matsubara, E.

    2014-01-01

    The diffraction anomalous fine structure method has been revisited by applying this measurement technique to polycrystalline samples and using an analytical method with the logarithmic dispersion relation. The diffraction anomalous fine structure (DAFS) method that is a spectroscopic analysis combined with resonant X-ray diffraction enables the determination of the valence state and local structure of a selected element at a specific crystalline site and/or phase. This method has been improved by using a polycrystalline sample, channel-cut monochromator optics with an undulator synchrotron radiation source, an area detector and direct determination of resonant terms with a logarithmic dispersion relation. This study makes the DAFS method more convenient and saves a large amount of measurement time in comparison with the conventional DAFS method with a single crystal. The improved DAFS method has been applied to some model samples, Ni foil and Fe 3 O 4 powder, to demonstrate the validity of the measurement and the analysis of the present DAFS method

  14. Revisiting the Survival Mnemonic Effect in Children

    Directory of Open Access Journals (Sweden)

    Josefa N. S. Pand Eirada

    2014-04-01

    Full Text Available The survival processing paradigm is designed to explore the adaptive nature of memory functioning. The mnemonic advantage of processing information in fitness-relevant contexts, as has been demonstrated using this paradigm, is now well established, particularly in young adults; this phenomenon is often referred to as the “survival processing effect.” In the current experiment, we revisited the investigation of this effect in children and tested it in a new cultural group, using a procedure that differs from the existing studies with children. A group of 40 Portuguese children rated the relevance of unrelated words to a survival and a new moving scenario. This encoding task was followed by a surprise free-recall task. Akin to what is typically found, survival processing produced better memory performance than the control condition (moving. These data put on firmer ground the idea that a mnemonic tuning to fitness-relevant encodings is present early in development. The theoretical importance of this result to the adaptive memory literature is discussed, as well as potential practical implications of this kind of approach to the study of memory in children.

  15. Differential cross sections for inelastic scattering of electrons on Kr and Xe atoms at intermediate energies

    International Nuclear Information System (INIS)

    Filipovic, D.M.

    1989-01-01

    Electron-impact excitation of the larger- number noble-gas atoms is a way of understanding excitation mechanisms in atomic collisional processes. Krypton and xenon have the largest atomic number of all the stable noble gases. Therefore, effects dependent on the size of a target atom, such as alignment and orientation of the atomic outer shell charge cloud after collisional excitation, are best observed by studying these atoms. Normalized, absolute differential cross sections (DCS's) for the lowest electronic states of Kr and Xe atoms, at intermediate energies, are the subject of this report

  16. Theoretical study of adsorption of lithium atom on carbon nanotube

    Directory of Open Access Journals (Sweden)

    Masato Senami

    2011-12-01

    Full Text Available We investigate the adsorption of lithium atoms on the surface of the (12,0 single wall carbon nanotube (SWCNT by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsive force between lithium atoms destabilizes a system for the large number of lithium atoms.

  17. Control and manipulation of cold atoms in optical tweezers

    International Nuclear Information System (INIS)

    Muldoon, Cecilia; Brandt, Lukas; Dong Jian; Stuart, Dustin; Brainis, Edouard; Himsworth, Matthew; Kuhn, Axel

    2012-01-01

    Neutral atoms trapped by laser light are among the most promising candidates for storing and processing information in a quantum computer or simulator. The application certainly calls for a scalable and flexible scheme for addressing and manipulating the atoms. We have now made this a reality by implementing a fast and versatile method to dynamically control the position of neutral atoms trapped in optical tweezers. The tweezers result from a spatial light modulator (SLM) controlling and shaping a large number of optical dipole-force traps. Trapped atoms adapt to any change in the potential landscape, such that one can rearrange and randomly access individual sites within atom-trap arrays. (paper)

  18. Plasmonic enhancement of High Harmonic Generation revisited: Predominance of Atomic Line Emission

    Directory of Open Access Journals (Sweden)

    Ropers C.

    2013-03-01

    Full Text Available We demonstrate nanostructure-enhanced extreme ultraviolet fluorescence from noble gases driven by low-energy, few-cycle light pulses. Despite sufficient local intensities, plasmon-enhanced high harmonic generation is not observed, which follows from the small, nanometer-size coherent source volume.

  19. Number Sense on the Number Line

    Science.gov (United States)

    Woods, Dawn Marie; Ketterlin Geller, Leanne; Basaraba, Deni

    2018-01-01

    A strong foundation in early number concepts is critical for students' future success in mathematics. Research suggests that visual representations, like a number line, support students' development of number sense by helping them create a mental representation of the order and magnitude of numbers. In addition, explicitly sequencing instruction…

  20. 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