7,867 research outputs found
NASA/JPL Aircraft SAR Workshop Proceedings
Speaker-supplied summaries of the talks given at the NASA/JPL Aircraft SAR Workshop on February 4 and 5, 1985, are provided. These talks dealt mostly with composite quadpolarization imagery from a geologic or ecologic prespective. An overview and summary of the system characteristics of the L-band synthetic aperture radar (SAR) flown on the NASA CV-990 aircraft are included as supplementary information. Other topics ranging from phase imagery and interferometric techniques classifications of specific areas, and the potentials and limitations of SAR imagery in various applications are discussed
Kinks: Fingerprints of strong electronic correlations
The textbook knowledge of solid state physics is that the electronic specific
heat shows a linear temperature dependence with the leading corrections being a
cubic term due to phonons and a cubic-logarithmic term due to the interaction
of electrons with bosons. We have shown that this longstanding conception needs
to be supplemented since the generic behavior of the low-temperature electronic
specific heat includes a kink if the electrons are sufficiently strongly
correlatedComment: 4 pages, 1 figure, ICM 2009 conference proceedings (to appear in
Journal of Physics: Conference Series
GdI_2: A New Ferromagnetic Excitonic Solid?
The two-dimensional, colossal magnetoresistive system GdI_2 develops an
unusual metallic state below its ferromagnetic transition and becomes
insulating at low temperatures. It is argued that this geometrically
frustrated, correlated poor metal is a possible candidate for a ferromagnetic
excitonic liquid. The renormalized Fermi surface supports a further breaking of
symmetry to a charge ordered, excitonic solid ground state at lower
temperatures via order by disorder mechanism. Several experimental predictions
are made to investigate this unique orbitally correlated ground state.Comment: 4 pages, 4 figures, changed Fig. 1 with extended energy scale, added
text and references, author list shortene
LDA+DMFT Spectral Functions and Effective Electron Mass Enhancement in Superconductor LaFePO
In this Letter we report the first LDA+DMFT results (method combining Local
Density Approximation with Dynamical Mean-Field Theory) for spectral properties
of superconductor LaFePO. Calculated {\bf k}-resolved spectral functions
reproduce recent angle-resolved photoemission spectroscopy (ARPES) data [D. H.
Lu {\it et al}., Nature {\bf 455}, 81 (2008)]. Obtained effective electron mass
enhancement values 1.9 -- 2.2 are in good agreement with
infrared and optical studies [M. M. Qazilbash {\it et al}., Nature Phys. {\bf
5}, 647 (2009)], de Haas--van Alphen, electrical resistivity, and electronic
specific heat measurements results, that unambiguously evidence for moderate
correlations strength in LaFePO. Similar values of were found in the
other Fe-based superconductors with substantially different superconducting
transition temperatures. Thus, the dynamical correlation effects are essential
in the Fe-based superconductors, but the strength of electronic correlations
does not determine the value of superconducting transition temperature.Comment: 4 pages, 3 figure
NiO: Correlated Bandstructure of a Charge-Transfer Insulator
The bandstructure of the prototypical charge-transfer insulator NiO is
computed by using a combination of an {\it ab initio} bandstructure method and
the dynamical mean-field theory with a quantum Monte-Carlo impurity solver.
Employing a Hamiltonian which includes both Ni-d and O-p orbitals we find
excellent agreement with the energy bands determined from angle-resolved
photoemission spectroscopy. This solves a long-standing problem in solid state
theory. Most notably we obtain the low-energy Zhang-Rice bands with strongly
k-dependent orbital character discussed previously in the context of low-energy
model theories.Comment: 4 pages, 3 figur
Orbital selective insulator-metal transition in V2O3 under external pressure
We present a detailed account of the physics of Vanadium sesquioxide (), a benchmark system for studying correlation induced metal-insulator
transition(s). Based on a detailed perusal of a wide range of experimental
data, we stress the importance of multi-orbital Coulomb interactions in concert
with first-principles LDA bandstructure for a consistent understanding of the
PI-PM MIT under pressure. Using LDA+DMFT, we show how the MIT is of the orbital
selective type, driven by large changes in dynamical spectral weight in
response to small changes in trigonal field splitting under pressure. Very good
quantitative agreement with () the switch of orbital occupation and ()
S=1 at each site across the MIT, and () carrier effective mass in
the PM phase, is obtained. Finally, using the LDA+DMFT solution, we have
estimated screening induced renormalisation of the local, multi-orbital Coulomb
interactions. Computation of the one-particle spectral function using these
screened values is shown to be in excellent quantitative agreement with very
recent experimental (PES and XAS) results. These findings provide strong
support for an orbital-selective Mott transition in paramagnetic .Comment: 12 pages, 7 figure
On the nature of the magnetic ground-state wave function of V_2O_3
After a brief historical introduction, we dwell on two recent experiments in
the low-temperature, monoclinic phase of V_2O_3: K-edge resonant x-ray
scattering and non-reciprocal linear dichroism, whose interpretations are in
conflict, as they require incompatible magnetic space groups. Such a conflict
is critically reviewed, in the light of the present literature, and new
experimental tests are suggested, in order to determine unambiguously the
magnetic group. We then focus on the correlated, non-local nature of the
ground-state wave function, that is at the basis of some drawbacks of the LDA+U
approach: we singled out the physical mechanism that makes LDA+U unreliable,
and indicate the way out for a possible remedy. Finally we explain, by means of
a symmetry argument related to the molecular wave function, why the magnetic
moment lies in the glide plane, even in the absence of any local symmetry at
vanadium sites.Comment: 7 pages, 1 figur
Halving Balls in Deterministic Linear Time
Let \D be a set of pairwise disjoint unit balls in and the
set of their center points. A hyperplane \Hy is an \emph{-separator} for
\D if each closed halfspace bounded by \Hy contains at least points
from . This generalizes the notion of halving hyperplanes, which correspond
to -separators. The analogous notion for point sets has been well studied.
Separators have various applications, for instance, in divide-and-conquer
schemes. In such a scheme any ball that is intersected by the separating
hyperplane may still interact with both sides of the partition. Therefore it is
desirable that the separating hyperplane intersects a small number of balls
only. We present three deterministic algorithms to bisect or approximately
bisect a given set of disjoint unit balls by a hyperplane: Firstly, we present
a simple linear-time algorithm to construct an -separator for balls
in , for any , that intersects at most
balls, for some constant that depends on and . The number of
intersected balls is best possible up to the constant . Secondly, we present
a near-linear time algorithm to construct an -separator in
that intersects balls. Finally, we give a linear-time algorithm to
construct a halving line in that intersects
disks.
Our results improve the runtime of a disk sliding algorithm by Bereg,
Dumitrescu and Pach. In addition, our results improve and derandomize an
algorithm to construct a space decomposition used by L{\"o}ffler and Mulzer to
construct an onion (convex layer) decomposition for imprecise points (any point
resides at an unknown location within a given disk)
Heritable CRISPR/Cas9-Mediated Genome Editing in the Yellow Fever Mosquito, Aedes aegypti
Citation: Dong, S. Z., Lin, J. Y., Held, N. L., Clem, R. J., Passarelli, A. L., & Franz, A. W. E. (2015). Heritable CRISPR/Cas9-Mediated Genome Editing in the Yellow Fever Mosquito, Aedes aegypti. Plos One, 10(3), 13. doi:10.1371/journal.pone.0122353In vivo targeted gene disruption is a powerful tool to study gene function. Thus far, two tools for genome editing in Aedes aegypti have been applied, zinc-finger nucleases (ZFN) and transcription activator-like effector nucleases (TALEN). As a promising alternative to ZFN and TALEN, which are difficult to produce and validate using standard molecular biological techniques, the clustered regularly interspaced short palindromic repeats/CRISPR-associated sequence 9 (CRISPR/Cas9) system has recently been discovered as a "do-it-yourself" genome editing tool. Here, we describe the use of CRISPR/Cas9 in the mosquito vector, Aedes aegypti. In a transgenic mosquito line expressing both Dsred and enhanced cyan fluorescent protein (ECFP) from the eye tissue-specific 3xP3 promoter in separated but tightly linked expression cassettes, we targeted the ECFP nucleotide sequence for disruption. When supplying the Cas9 enzyme and two sgRNAs targeting different regions of the ECFP gene as in vitro transcribed mRNAs for germline transformation, we recovered four different G1 pools (5.5% knockout efficiency) where individuals still expressed DsRed but no longer ECFP. PCR amplification, cloning, and sequencing of PCR amplicons revealed indels in the ECFP target gene ranging from 2-27 nucleotides. These results show for the first time that CRISPR/Cas9 mediated gene editing is achievable in Ae. aegypti, paving the way for further functional genomics related studies in this mosquito species
Exchange coupling in Eu monochalcogenides from first principles
Using a density functional method with explicit account for strong Coulomb
repulsion within the 4f shell, we calculate effective exchange parameters and
the corresponding ordering temperatures of the (ferro)magnetic insulating Eu
monochalcogenides (EuX; X=O,S,Se,Te) at ambient and elevated pressure
conditions. Our results provide quantitative account of the many-fold increase
of the Curie temperatures with applied pressure and reproduce well the
enhancement of the tendency toward ferromagnetic ordering across the series
from telluride to oxide, including the crossover from antiferromagnetic to
ferromagnetic ordering under pressure in EuTe and EuSe. The first and second
neighbor effective exchange are shown to follow different functional
dependencies. Finally, model calculations indicate a significant contribution
of virtual processes involving the unoccupied f states to the effective
exchange.Comment: 4 pages, 6 figure
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