9,111 research outputs found
Investigation of planetary ionospheres
Feasibility of using radio sounding techniques to investigate ionospheric properties of planet
QED self-energy contribution to highly-excited atomic states
We present numerical values for the self-energy shifts predicted by QED
(Quantum Electrodynamics) for hydrogenlike ions (nuclear charge ) with an electron in an , 4 or 5 level with high angular momentum
(). Applications include predictions of precision transition
energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure
Different disk structures in the hexagonal columnar mesophases of 2,3-dicyano-6,7,10,11-tetraalkoxy-1,4-diazatriphenylenes and 2,3-dicyano-6,7,10,11-tetraalkoxytriphenylenes
This is an electronic version of an article published in Liquid Crystals. 34(3): 401-410 (2007). "Liquid Crystals" is available online at: http://www.informaworld.com/openurl?genre=article&issn=0267-8292&volume=34&issue=3&spage=401ArticleLIQUID CRYSTALS. 34(1-3): 401-410 (2007)journal articl
Analysis of No-Difference Findings in Evaluation Research
Conclusions of no difference are becoming increasingly important in evaluation research. We delineate three major uses of no-difference findings and analyze their meanings. (1) No-differ ence findings in randomized experiments can be interpreted as support for conclusions of the absence of a meaningful treatment effect, but only if the proper analytic methods are used. (2) Statistically based conclusions in quasi-experiments do not allow causal statements about the treatment impact but do provide a metric to judge the size of the resulting difference. (3) Using no-difference findings to conclude equivalence on control variables is inefficient and potentially misleading. The final section of the article presents alternative methods by which conclusions of no difference may be supported when applicable. These methods include the use of arbitrarily high alpha levels, interval estimation, and power analysis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67182/2/10.1177_0193841X8901300604.pd
Calculation of the Electron Self Energy for Low Nuclear Charge
We present a nonperturbative numerical evaluation of the one-photon electron
self energy for hydrogenlike ions with low nuclear charge numbers Z=1 to 5. Our
calculation for the 1S state has a numerical uncertainty of 0.8 Hz for hydrogen
and 13 Hz for singly-ionized helium. Resummation and convergence acceleration
techniques that reduce the computer time by about three orders of magnitude
were employed in the calculation. The numerical results are compared to results
based on known terms in the expansion of the self energy in powers of (Z
alpha).Comment: 10 pages, RevTeX, 2 figure
alpha-nucleus potentials for the neutron-deficient p nuclei
alpha-nucleus potentials are one important ingredient for the understanding
of the nucleosynthesis of heavy neutron-deficient p nuclei in the astrophysical
gamma-process where these p nuclei are produced by a series of (gamma,n),
(gamma,p), and (gamma,alpha) reactions. I present an improved alpha-nucleus
potential at the astrophysically relevant sub-Coulomb energies which is derived
from the analysis of alpha decay data and from a previously established
systematic behavior of double-folding potentials.Comment: 6 pages, 3 figures, accepted for publication in Phys. Rev.
Electron Self Energy for the K and L Shell at Low Nuclear Charge
A nonperturbative numerical evaluation of the one-photon electron self energy
for the K- and L-shell states of hydrogenlike ions with nuclear charge numbers
Z=1 to 5 is described. Our calculation for the 1S state has a numerical
uncertainty of 0.8 Hz in atomic hydrogen, and for the L-shell states (2S and
2P) the numerical uncertainty is 1.0 Hz. The method of evaluation for the
ground state and for the excited states is described in detail. The numerical
results are compared to results based on known terms in the expansion of the
self energy in powers of (Z alpha).Comment: 21 pages, RevTeX, 5 Tables, 6 figure
Listening to limericks: a pupillometry investigation of perceivers’ expectancy
What features of a poem make it captivating, and which cognitive mechanisms are sensitive to these features? We addressed these questions experimentally by measuring pupillary responses of 40 participants who listened to a series of Limericks. The Limericks ended with either a semantic, syntactic, rhyme or metric violation. Compared to a control condition without violations, only the rhyme violation condition induced a reliable pupillary response. An anomaly-rating study on the same stimuli showed that all violations were reliably detectable relative to the control condition, but the anomaly induced by rhyme violations was perceived as most severe. Together, our data suggest that rhyme violations in Limericks may induce an emotional response beyond mere anomaly detection
Evaluation of the low-lying energy levels of two- and three-electron configurations for multi-charged ions
Accurate QED evaluations of the one- and two-photon interelectron interaction
for low lying two- and three-electron configurations for ions with nuclear
charge numbers are performed. The three-photon interaction is
also partly taken into account. The Coulomb gauge is employed. The results are
compared with available experimental data and with different calculations. A
detailed investigation of the behaviour of the energy levels of the
configurations , near
the crossing points Z=64 and Z=92 is carried out. The crossing points are
important for the future experimental search for parity nonconserving (PNC)
effects in highly charged ions
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