41,477 research outputs found
A study of the usefulness of Skylab EREP data for earth resources studies in Australia
The author has identified the following significant results. Preliminary results show that the high resolution imagery has, potentially, an operational role in geological surveying and the design of major engineering works, and is much more promising in this regard than the low resolution Skylab and ERTS-1 imagery
Fluctuating loops and glassy dynamics of a pinned line in two dimensions
We represent the slow, glassy equilibrium dynamics of a line in a
two-dimensional random potential landscape as driven by an array of
asymptotically independent two-state systems, or loops, fluctuating on all
length scales. The assumption of independence enables a fairly complete
analytic description. We obtain good agreement with Monte Carlo simulations
when the free energy barriers separating the two sides of a loop of size L are
drawn from a distribution whose width and mean scale as L^(1/3), in agreement
with recent results for scaling of such barriers.Comment: 11 pages, 4 Postscript figure
Atypical energy eigenstates in the Hubbard chain and quantum disentangled liquids
We investigate the implications of integrability for the existence of quantum
disentangled liquid (QDL) states in the half-filled one-dimensional Hubbard
model. We argue that there exist finite energy-density eigenstates that exhibit
QDL behaviour in the sense of J. Stat. Mech. P10010 (2014). These states are
atypical in the sense that their entropy density is smaller than that of
thermal states at the same energy density. Furthermore, we show that thermal
states in a particular temperature window exhibit a weaker form of the QDL
property, in agreement with recent results obtained by strong-coupling
expansion methods in arXiv:1611.02075. This article is part of the themed issue
`Breakdown of ergodicity in quantum systems: from solids to synthetics matter'.Comment: 11 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1611.0207
Flight investigation of the VFR and IFR landing approach characteristics and terminal area airspace requirements for a light STOL airplane
A flight research program was conducted to determine the terminal area instrument flight capabilities of a light STOL airplane. Simulated (hooded) instrument landing approaches were made using steep single-segment and two-segment glide slopes. A brief investigation was also made of the visual flight terminal area capabilities of the aircraft. The results indicated that the airplane could be flown on a 7 deg glide-slope ILS-type approach in still air with an adequate 3 deg margin for downward correction
Analysis of the effectiveness of industrial R and D
The criteria used by private industry in evaluating and selecting proposed research and development projects for implementation, and also in determining which R and D facilities are to be acquired were investigated. Conceptual and practical issues inherent in any quantitative analysis of the contribution of R and D to economic growth were identified in order to assist NASA in developing approaches for analzying the economic implication of its own R and D efforts
Transfer of Graphene with Protective Oxide Layers
Transfer of graphene, grown by Chemical Vapor Deposition (CVD), to a
substrate of choice, typically involves deposition of a polymeric layer
(typically, poly(methyl methacrylate, PMMA or polydimethylsiloxane, PDMS).
These polymers are quite hard to remove without leaving some residues behind.
Here we study a transfer of graphene with a protective thin oxide layer. The
thin oxide layer is grown by Atomic Deposition Layer (ALD) on the graphene
right after the growth stage on Cu foils. One can further aid the
oxide-graphene transfer by depositing a very thin polymer layer on top of the
composite (much thinner than the usual thickness) following by a more
aggressive polymeric removal methods, thus leaving the graphene intact. We
report on the nucleation growth process of alumina and hafnia films on the
graphene, their resulting strain and on their optical transmission. We suggest
that hafnia is a better oxide to coat the graphene than alumina in terms of
uniformity and defects.Comment: 13 pgs, 13 figure
Probability distribution of the order parameter in the directed percolation universality class
The probability distributions of the order parameter for two models in the
directed percolation universality class were evaluated. Monte Carlo simulations
have been performed for the one-dimensional generalized contact process and the
Domany-Kinzel cellular automaton. In both cases, the density of active sites
was chosen as the order parameter. The criticality of those models was obtained
by solely using the corresponding probability distribution function. It has
been shown that the present method, which has been successfully employed in
treating equilibrium systems, is indeed also useful in the study of
nonequilibrium phase transitions.Comment: 6 pages, 4 figure
Impairments in motor coordination without major changes in cerebellar plasticity in the Tc1 mouse model of Down syndrome
Down syndrome (DS) is a genetic disorder arising from the presence of a third copy of human chromosome
21 (Hsa21). Recently, O’Doherty et al. [An aneuploid mouse strain carrying human chromosome 21 with Down
syndrome phenotypes. Science 309 (2005) 2033–2037] generated a trans-species aneuploid mouse line (Tc1)
that carries an almost complete Hsa21. The Tc1 mouse is the most complete animal model for DS currently
available. Tc1 mice show many features that relate to human DS, including alterations in memory, synaptic
plasticity, cerebellar neuronal number, heart development and mandible size. Because motor deficits are
one of the most frequently occurring features of DS, we have undertaken a detailed analysis of motor behaviour
in cerebellum-dependent learning tasks that require high motor coordination and balance. In addition,
basic electrophysiological properties of cerebellar circuitry and synaptic plasticity have been investigated.
Our results reveal that, compared with controls, Tc1 mice exhibit a higher spontaneous locomotor activity,
a reduced ability to habituate to their environments, a different gait and major deficits on several measures
of motor coordination and balance in the rota rod and static rod tests. Moreover, cerebellar long-term
depression is essentially normal in Tc1 mice, with only a slight difference in time course. Our observations
provide further evidence that support the validity of the Tc1 mouse as a model for DS, which will help us to
provide insights into the causal factors responsible for motor deficits observed in persons with DS
Charge dynamics of the spin-density-wave state in BaFeAs
We report on a thorough optical investigation of BaFeAs over a broad
spectral range and as a function of temperature, focusing our attention on its
spin-density-wave (SDW) phase transition at K. While
BaFeAs remains metallic at all temperatures, we observe a depletion in
the far infrared energy interval of the optical conductivity below ,
ascribed to the formation of a pseudogap-like feature in the excitation
spectrum. This is accompanied by the narrowing of the Drude term consistent
with the transport results and suggestive of suppression of scattering
channels in the SDW state. About 20% of the spectral weight in the far infrared
energy interval is affected by the SDW phase transition
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