340 research outputs found
Boltzmann-type approach to transport in weakly interacting one-dimensional fermionic systems
We investigate transport properties of one-dimensional fermionic tight
binding models featuring nearest and next-nearest neighbor hopping, where the
fermions are additionally subject to a weak short range mutual interaction. To
this end we employ a pertinent approach which allows for a mapping of the
underlying Schr\"odinger dynamics onto an adequate linear quantum Boltzmann
equation. This approach is based on a suitable projection operator method. From
this Boltzmann equation we are able to numerically obtain diffusion
coefficients in the case of non-vanishing next-nearest neighbor hopping, i.e.,
the non-integrable case, whereas the diffusion coefficient diverges without
next-nearest neighbor hopping. For the latter case we analytically investigate
the decay behavior of the current with the result that arbitrarily small parts
of the current relax arbitrarily slowly which suggests anomalous diffusive
transport behavior within the scope of our approach.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.
Drosophila anterior determination is independent of bicoid morphogenic functions but depends on activating versus repressing inputs on the level of target gene enhancers.
Restricted expression and subnuclear localisation of the Drosophila gene Dnop5, a member of the Nop/Sik family of the conserved rRNA processing factors.
Lipid droplets: A dynamic organelle moves into focus.
Lipid droplets (LDs) were perceived as static storage deposits, which passively participate in the energy homeostasis of both cells and entire organisms. However, this view has changed recently after the realization of a complex and highly dynamic LD proteome. The proteome contains key components of the fat mobilization system and proteins that suggest LD interactions with a variety of cell organelles, including the endoplasmic reticulum, mitochondria and peroxisomes. The study of LD cell biology, including cross-talk with other organelles, the trafficking of LDs in the cell and regulatory events involving the LD coat proteins is now on the verge of leaving its infancy and unfolds that LDs are highly dynamic cellular organelles
SelD homolog from Drosophila lacking selenide-dependent monoselenophosphate synthetase activity
Mutations of the Drosophila zinc finger-encoding gene vielfältig impair mitotic cell divisions and cause improper chromosome segretation.
curled encodes the Drosophila homolog of the vertebrate circadian deadenylase nocturnin.
The Drosophila gene abstrakt, required for visual system development, encodes a putative RNA helicase of the DEAD box protein family.
Absence of surface mode in a visco-elastic material with surface tension
The surface waves in the visco-elastic media with the surface tension are
studied using the Voigt-Kelvin model of the visco-elasticity. It is shown that
the surface mode of oscillation does not exist in the parameter region where
the effect of surface tension is larger than that of the elastic stress at the
surface unless the viscous stress masks the elastic stress in the bulk. In the
region, the surface oscillation is suppressed and the oscillation beneath the
surface diffuses after the pulse goes into the bulk. The experimental relevance
of the present results is also discussed.Comment: 5 pages, 3 figure
Binding between two-component bosons in one dimension
We investigate the ground state of one-dimensional few-atom Bose-Bose
mixtures under harmonic confinement throughout the crossover from weak to
strong inter-species attraction. The calculations are based on the numerically
exact multi-configurational time-dependent Hartree method. For repulsive
components we detail the condition for the formation of a molecular
Tonks-Girardeau gas in the regime of intermediate inter-species interactions,
and the formation of a molecular condensate for stronger coupling. Beyond a
critical inter-species attraction, the system collapses to an overall bound
state. Different pathways emerge for unequal particle numbers and intra-species
interactions. In particular, for mixtures with one attractive component, this
species can be viewed as an effective potential dimple in the trap center for
the other, repulsive component.Comment: 10 pages, 10 figure
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