1,420 research outputs found
Feasibility study of the application of existing techniques to remotely monitor hydrochloric acid in the atmosphere
A critical evaluation of existing optical remote sensors for HCl vapor detection in solid propellant rocket plumes is presented. The P branch of the fundamental vibration-rotation band was selected as the most promising spectral feature to sense. A computation of transmittance for HCl vapor, an estimation of interferent spectra, the application of these spectra to computer modelled remote sensors, and a trade-off study for instrument recommendation are also included
Home range and habitat use by Kemp's Ridley turtles in West-Central Florida
The Kemp's ridley turtle (Lepidochelys kempii) is an endangered species whose recovery depends in part on
the identification and protection of required habitats. We used radio and sonic telemetry on subadult Kemp's ridley
turtles to investigate home-range size and habitat use in the coastal waters of west-central Florida from 1994 to
1996. We tracked 9 turtles during May-August up to 70 days after release and fou.ld they occupied 5-30 km2 foraging
ranges. Compositional analyses indicated that turtles used rock outcroppings in their foraging ranges at a
significantly higher proportion than expected. based on availability within the study area. Additionally. turtles used
live bottom (e.g .• sessile invertebrates) and green macroalgae habitats significantly more than seagrass habitat. Similar
studies are needed through'mt the Kemp's ridley turtles' range to investigate regional and stage-specific differences
in habitat use. which can then be used to conserve important foraging areas
Finding the Minimum-Weight k-Path
Given a weighted -vertex graph with integer edge-weights taken from a
range , we show that the minimum-weight simple path visiting
vertices can be found in time \tilde{O}(2^k \poly(k) M n^\omega) = O^*(2^k
M). If the weights are reals in , we provide a
-approximation which has a running time of \tilde{O}(2^k
\poly(k) n^\omega(\log\log M + 1/\varepsilon)). For the more general problem
of -tree, in which we wish to find a minimum-weight copy of a -node tree
in a given weighted graph , under the same restrictions on edge weights
respectively, we give an exact solution of running time \tilde{O}(2^k \poly(k)
M n^3) and a -approximate solution of running time
\tilde{O}(2^k \poly(k) n^3(\log\log M + 1/\varepsilon)). All of the above
algorithms are randomized with a polynomially-small error probability.Comment: To appear at WADS 201
The tropical shadow-vertex algorithm solves mean payoff games in polynomial time on average
We introduce an algorithm which solves mean payoff games in polynomial time
on average, assuming the distribution of the games satisfies a flip invariance
property on the set of actions associated with every state. The algorithm is a
tropical analogue of the shadow-vertex simplex algorithm, which solves mean
payoff games via linear feasibility problems over the tropical semiring
. The key ingredient in our approach is
that the shadow-vertex pivoting rule can be transferred to tropical polyhedra,
and that its computation reduces to optimal assignment problems through
Pl\"ucker relations.Comment: 17 pages, 7 figures, appears in 41st International Colloquium, ICALP
2014, Copenhagen, Denmark, July 8-11, 2014, Proceedings, Part
Long quantum channels for high-quality entanglement transfer
High-quality quantum-state and entanglement transfer can be achieved in an
unmodulated spin bus operating in the ballistic regime, which occurs when the
endpoint qubits A and B are coupled to the chain by an exchange interaction
comparable with the intrachain exchange. Indeed, the transition amplitude
characterizing the transfer quality exhibits a maximum for a finite optimal
value , where is the channel length. We show that
scales as for large and that it ensures a
high-quality entanglement transfer even in the limit of arbitrarily long
channels, almost independently of the channel initialization. For instance, the
average quantum-state transmission fidelity exceeds 90% for any chain length.
We emphasize that, taking the reverse point of view, should be
experimentally constrained, high-quality transfer can still be obtained by
adjusting the channel length to its optimal value.Comment: 12 pages, 9 figure
Quantum state transfer in a XX chain with impurities
One spin excitation states are involved in the transmission of quantum states
and entanglement through a quantum spin chain, the localization properties of
these states are crucial to achieve the transfer of information from one
extreme of the chain to the other. We investigate the bipartite entanglement
and localization of the one excitation states in a quantum chain with one
impurity. The bipartite entanglement is obtained using the Concurrence and the
localization is analyzed using the inverse participation ratio. Changing the
strength of the exchange coupling of the impurity allows us to control the
number of localized or extended states. The analysis of the inverse
participation ratio allows us to identify scenarios where the transmission of
quantum states or entanglement can be achieved with a high degree of fidelity.
In particular we identify a regime where the transmission of quantum states
between the extremes of the chain is executed in a short transmission time
, where is the number of spins in the chain, and with a large
fidelity
A 200 GHz Monolithic Integrated Power Amplifier in Metamorphic HEMT Technology
A millimeter-wave monolithic integrated circuit power amplifier operating in the frequency range between 186 and 212 GHz is presented. The amplifier, dedicated to high-resolution imaging radar and communication systems, is realized in a 100 nm gate length metamorphic high electron mobility transistor technology. The three-stage design with four parallel transistors in the output stage achieves a linear gain of more than 12 dB and provides a saturated output power of more than 9 dBm and 7 dBm at 192 and 200 GHz, respectively
Boundary effects on one-particle spectra of Luttinger liquids
We calculate one-particle spectra for a variety of models of Luttinger
liquids with open boundary conditions. For the repulsive Hubbard model the
spectral weight close to the boundary is enhanced in a large energy range
around the chemical potential. A power law suppression, previously predicted by
bosonization, only occurs after a crossover at energies very close to the
chemical potential. Our comparison with exact spectra shows that the effects of
boundaries can partly be understood within the Hartree-Fock approximation.Comment: 4 pages including 4 figures, revised version, to be published in
Phys. Rev. B, January 200
How universal is the one-particle Green's function of a Luttinger liquid?
The one-particle Green's function of the Tomonaga-Luttinger model for
one-dimensional interacting Fermions is discussed. Far away from the origin of
the plane of space-time coordinates the function falls off like a power law.
The exponent depends on the direction within the plane. For a certain form of
the interaction potential or within an approximated cut-off procedure the
different exponents only depend on the strength of the interaction at zero
momentum and can be expressed in terms of the Luttinger liquid parameters
and of the model at hand. For a more general
interaction and directions which are determined by the charge velocity
and spin velocity the exponents also depend on the
smoothness of the interaction at zero momentum and the asymptotic behavior of
the Green's function is not given by the Luttinger liquid parameters alone.
This shows that the physics of large space-time distances in Luttinger liquids
is less universal than is widely believed.Comment: 5 pages with 2 figure
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