21,268 research outputs found
Ghost imaging without beam splitter
Many significant results have been achieved in the fields of ghost imaging,
in which the beam splitter is an indispensable optical component. This paper
introduces a method to realize ghost imaging without beam splitter. And we
study this method experimentally and theoretically. Finally, we suggest that
our device can be applied to implement the ghost imaging when we use the Sun
light as the light source
Subminiature micropower digital recorder
High-density digital data, collected periodically or randomly from multiplicity of sensors, are recorded by subminiature recorder. Magnetic recording head is energized with suitable pulsatile signals to reverse polarization on magnetically-sensitive tape while tape is immobilized at recording head. Prior to next recording, set tape so new area of tape is at recording head
Competition Between T=0 and T=1 Pairing in Proton-Rich Nuclei
A cranked mean-field model with two-body T=1 and T=0 pairing interactions is
presented. Approximate projection onto good particle-number is enforced via an
extended Lipkin-Nogami scheme. Our calculations suggest the simultaneous
presence of both T=0 and T=1 pairing modes in N=Z nuclei. The transitions
between different pairing phases are discussed as a function of neutron/proton
excess, T, and rotational frequency, . The additional binding
energy due to the T=0 -pairing correlations, is suggested as a possible
microscopic explanation of the Wigner energy term in even-even nuclei.Comment: 8 RevTeX pages, 3 uuencoded POSTSCRIPT figures include
Correlations and fluctuations of a confined electron gas
The grand potential and the response of a phase-coherent confined noninteracting electron gas depend
sensitively on chemical potential or external parameter . We compute
their autocorrelation as a function of , and temperature. The result
is related to the short-time dynamics of the corresponding classical system,
implying in general the absence of a universal regime. Chaotic, diffusive and
integrable motions are investigated, and illustrated numerically. The
autocorrelation of the persistent current of a disordered mesoscopic ring is
also computed.Comment: 12 pages, 1 figure, to appear in Phys. Rev.
Low fertility increases descendant socioeconomic position but reduces long-term fitness in a modern post-industrial society.
Adaptive accounts of modern low human fertility argue that small family size maximizes the inheritance of socioeconomic resources across generations and may consequently increase long-term fitness. This study explores the long-term impacts of fertility and socioeconomic position (SEP) on multiple dimensions of descendant success in a unique Swedish cohort of 14 000 individuals born during 1915-1929. We show that low fertility and high SEP predict increased descendant socioeconomic success across four generations. Furthermore, these effects are multiplicative, with the greatest benefits of low fertility observed when SEP is high. Low fertility and high SEP do not, however, predict increased descendant reproductive success. Our results are therefore consistent with the idea that modern fertility limitation represents a strategic response to the local costs of rearing socioeconomically competitive offspring, but contradict adaptive models suggesting that it maximizes long-term fitness. This indicates a conflict in modern societies between behaviours promoting socioeconomic versus biological success. This study also makes a methodological contribution, demonstrating that the number of offspring strongly predicts long-term fitness and thereby validating use of fertility data to estimate current selective pressures in modern populations. Finally, our findings highlight that differences in fertility and SEP can have important long-term effects on the persistence of social inequalities across generations
Nonlinear coherent transport of waves in disordered media
We present a diagrammatic theory for coherent backscattering from disordered
dilute media in the nonlinear regime. The approach is non-perturbative in the
strength of the nonlinearity. We show that the coherent backscattering
enhancement factor is strongly affected by the nonlinearity, and corroborate
these results by numerical simulations. Our theory can be applied to several
physical scenarios like scattering of light in nonlinear Kerr media, or
propagation of matter waves in disordered potentials.Comment: 4 pages, 3 figure
Workshop on dimensional analysis for design, development, and research executives
The proceedings of a conference of research and development executives are presented. The purpose of the meeting was to develop an understanding of the conditions which are appropriate for the use of certain general management tools and those conditions which render these tools inappropriate. The verbatim statements of the participants are included to show the direction taken initially by the conference. Formal presentations of management techniques for research and development are developed
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