2,309 research outputs found
Method for determining properties of microinstabilities of a magnetized plasma
Study comprises a determination of the plasma density at which absolute density becomes predominant by using the dielectric properties at this incipient unstable state. Relationships between wavelength, frequency, and density microinstabilities are used to derive the spatial dielectric function
The diocotron instability in a quasi-toroidal geometry
Slipstream instability of low density electron beams in crossed electric and magnetic field
Coherence properties of the microcavity polariton condensate
A theoretical model is presented which explains the dominant decoherence
process in a microcavity polariton condensate. The mechanism which is invoked
is the effect of self-phase modulation, whereby interactions transform
polariton number fluctuations into random energy variations. The model shows
that the phase coherence decay, g1(t), has a Kubo form, which can be Gaussian
or exponential, depending on whether the number fluctuations are slow or fast.
This fluctuation rate also determines the decay time of the intensity
correlation function, g2(t), so it can be directly determined experimentally.
The model explains recent experimental measurements of a relatively fast
Gaussian decay for g1(t), but also predicts a regime, further above threshold,
where the decay is much slower.Comment: 5 pages, 1 figur
Absolute and convective microinstabilities of a magnetized plasma
Absolute and convective microinstabilities of hot, fully ionized, collisionless magnetized plasm
Institutional corruption and election fraud: evidence from a field experiment in Afghanistan
We investigate the relationship between political networks, weak institutions, and election fraud during the 2010 parliamentary election in Afghanistan combining: (i) data on political connections between candidates and election officials; (ii) a nationwide controlled evaluation of a novel monitoring technology; and (iii) direct measurements of aggregation fraud. We find considerable evidence of aggregation fraud in favor of connected candidates and that the announcement of a new monitoring technology reduced theft of election materials by about 60 percent and vote counts for connected candidates by about 25 percent. The results have implications for electoral competition and are potentially actionable for policymakers
Thermopower of gapped bilayer graphene
We calculate thermopower of clean and impure bilayer graphene systems.
Opening a band gap through the application of an external electric field is
shown to greatly enhance the thermopower of bilayer graphene, which is more
than four times that of the monolayer graphene and gapless bilayer graphene at
room temperature. The effect of scattering by dilute charged impurities is
discussed in terms of the self-consistent Born approximation. Temperature
dependence of the thermopower is also analyzed.Comment: 8 pages, 5 figures; An inconsistency in the definitions of Eq.(17)
and (18) in version 1 is found and correcte
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