1,497 research outputs found

    Global budget of stratospheric trace constituents (GLOBUS). MAP/GLOBUS 1983: A review

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    MAP/GLOBUS 1983 was a project for the study of stratospheric trace gases and dynamics. A respective field campaign was performed in September/October 1983 in Western Europe. A large number of measurements were taken by instruments based on the ground, on airplane, balloons, and satellite. The structure of the campaign is described, and a survey of the results are given

    Middle atmosphere thermal structure during MAP/WINE

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    Middle atmosphere temperatures were measured during the MAP/WINE campaign by various ground-based techniques, by rocket instruments, and by satellites. Respective data were analyzed for atmospheric thermal mean state as well as for long and short period variations. A brief survey of the results is given. Monthly mean temperatures agree well with the new CIRA model. Long period (planetary) waves frequently exhibit peculiar vertical amplitude and phase structures, resembling those of standing waves. Short period oscillations tend to begin breaking well below the stratosphere

    Indications for the Nonexistence of Three-Neutron Resonances near the Physical Region

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    The pending question of the existence of three-neutron resonances near the physical energy region is reconsidered. Finite rank neutron-neutron forces are used in Faddeev equations, which are analytically continued into the unphysical energy sheet below the positive real energy axis. The trajectories of the three-neutron S-matrix poles in the states of total angular momenta and parity J^\pi=1/2 +- and J^\pi= 3/2 +- are traced out as a function of artificial enhancement factors of the neutron-neutron forces. The final positions of the S-matrix poles removing the artificial factors are found in all cases to be far away from the positive real energy axis, which provides a strong indication for the nonexistence of nearby three-neutron resonances. The pole trajectories close to the threshold E=0 are also predicted out of auxiliary generated three-neutron bound state energies using the Pad\'e method and agree very well with the directly calculated ones.Comment: 20 pages, 7 Postscript figures, fig.1 is corrected, uses relax.st

    Use of CRISTA mesopause region temperatures for the intercalibration of gound-based instruments

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    Most available ground-based (GB) techniques for measuring temperatures in the upper mesosphere to lower thermosphere (or mesopause region) have systematic errors that are comparable to those of orbiting instruments. Determining these unknown biasses would normally require colocated observations that are only seldom feasible. Satellite measurements can be used as a ‘‘transfer standard’’ between GB observations that are not colocated. In this context, even with a reproducible or known bias in the satellite data, the comparison is still meaningful. Since Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) temperatures cover the mesopause region with very good accuracy (statistical errors do not exceed 1.5 K and systematic uncertainties range from about 3–7.5 K), they are quite suitable for this purpose. Because of the nearly constant precision over the height range of interest, also rotational temperatures of airglow emissions from different altitudes like the OH and O2 bands (or the OI 558 nm line) can be successfully compared with each other. In spite of the limited number of overpasses during the relatively short CRISTA missions, the feasibility of such an intercalibration is demonstrated for widely separated GB sites. Here, the results obtained for GB measurements at eight different sites, using CRISTA-1 and CRISTA-2 data, are presented. For OH temperatures, the standard deviation between the different instruments is only 5.4 K, confirming previous estimates.Fil: Scheer, Jurgen. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Reisin, Esteban Rodolfo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gusev, O. A.. University of Wuppertal; AlemaniaFil: French, W. J. R.. Australian Antarctic Division; AustraliaFil: Hernandez, G.. University of Washington; Estados UnidosFil: Huppi, R.. State University Of Utah; Estados UnidosFil: Ammosov, P.. Institute of Cosmophysical Research and Aeronomy; RusiaFil: Gavrilyeva, G. A.. Institute of Cosmophysical Research and Aeronomy; RusiaFil: Offermann, D.. University of Wuppertal; Alemani

    Consistent alpha-cluster description of the 12C (0^+_2) resonance

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    The near-threshold 12C (0^+_2) resonance provides unique possibility for fast helium burning in stars, as predicted by Hoyle to explain the observed abundance of elements in the Universe. Properties of this resonance are calculated within the framework of the alpha-cluster model whose two-body and three-body effective potentials are tuned to describe the alpha - alpha scattering data, the energies of the 0^+_1 and 0^+_2 states, and the 0^+_1-state root-mean-square radius. The extremely small width of the 0^+_2 state, the 0_2^+ to 0_1^+ monopole transition matrix element, and transition radius are found in remarkable agreement with the experimental data. The 0^+_2-state structure is described as a system of three alpha-particles oscillating between the ground-state-like configuration and the elongated chain configuration whose probability exceeds 0.9

    Display of probability densities for data from a continuous distribution

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    Based on cumulative distribution functions, Fourier series expansion and Kolmogorov tests, we present a simple method to display probability densities for data drawn from a continuous distribution. It is often more efficient than using histograms.Comment: 5 pages, 4 figures, presented at Computer Simulation Studies XXIV, Athens, GA, 201

    The reaction dynamics of the 16O(e,e'p) cross section at high missing energies

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    We measured the cross section and response functions (R_L, R_T, and R_LT) for the 16O(e,e'p) reaction in quasielastic kinematics for missing energies 25 <= E_miss <= 120 MeV at various missing momenta P_miss <= 340 MeV/c. For 25 < E_miss < 50 MeV and P_miss \approx 60 MeV/c, the reaction is dominated by single-nucleon knockout from the 1s1/2-state. At larger P_miss, the single-particle aspects are increasingly masked by more complicated processes. For E_miss > 60 MeV and P_miss > 200 MeV/c, the cross section is relatively constant. Calculations which include contributions from pion exchange currents, isobar currents and short-range correlations account for the shape and the transversity but only for half of the magnitude of the measured cross section.Comment: 6 pages, 4 figures, submitted to Phys Rev Lett, formatting error fixe

    Large Momentum Transfer Measurements of the Deuteron Elastic Structure Function A(Q^2) at Jefferson Laboratory

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    The deuteron elastic structure function A(Q^2) has been extracted in the Q^2 range 0.7 to 6.0 (GeV/c)^2 from cross section measurements of elastic electron-deuteron scattering in coincidence using the Hall A Facility of Jefferson Laboratory. The data are compared to theoretical models based on the impulse approximation with inclusion of meson-exchange currents, and to predictions of quark dimensional scaling and perturbative quantum chromodynamicsComment: Submitted to Physical Review Letter

    What factors influence training opportunities for older workers? Three factorial surveys exploring the attitudes of HR professionals

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    The core research questions addressed in this paper are: what factors influence HR professionals in deciding whether to approve training proposals for older workers? What kind of training are they more likely to recommend for older employees and in which organizational contexts? We administered three factorial surveys to 66 HR professionals in Italy. Participants made specific training decisions based on profiles of hypothetical older workers. Multilevel analyses indicated that access to training decreases strongly with age, while highly-skilled older employees with low absenteeism rates are more likely to enjoy training opportunities. In addition, older workers displaying positive performance are more likely to receive training than older workers who perform poorly, suggesting that training late in working life may serve as a reward for good performance rather than as a means of enhancing productivity. The older the HR professional evaluating training proposals, the higher the probability that older workers will be recommended for training. keywords: training; older workers; HR professionals; factorial survey; multilevel model
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