5,409 research outputs found
WHAT IS THE LENGTH OF A SNAKE?
The way that herpetologists have traditionally measuredlive snakes is by stretching them on a ruler andrecording the total length (TL). However, due to the thinconstitution of the snake, the large number of intervertebraljoints, and slim muscular mass of most snakes,it is easier to stretch a snake than it is to stretch anyother vertebrate. The result of this is that the length ofa snake recorded is infl uenced by how much the animalis stretched. Stretching it as much as possible is perhapsa precise way to measure the length of the specimenbut it might not correspond to the actual length ofa live animal. Furthermore, it may seriously injure a livesnake. Another method involves placing the snake in aclear plexiglass box and pressing it with a soft materialsuch as rubber foam against a clear surface. Measuringthe length of the snake may be done by outlining itsbody with a string (Fitch 1987; Frye 1991). However, thismethod is restricted to small animals that can be placedin a box, and in addition, no indications of accuracy of thetechnique are given. Measuring the snakes with a fl exibletape has also been reported (Blouin-Demers 2003)but when dealing with a large animals the way the tapeis positioned can produce great variance on the fi nal outcome.In this contribution we revise alternative ways tomeasuring a snake and propose a method that offers repeatableresults. We further analyze the precision of thismethod by using a sample of measurements taken fromwild populations of green anacondas (Eunectes murinus)with a large range of sizes
Reactivity of dolomitizing fluids and Mg source evaluation of fault-controlled dolomitization at the BenicĂ ssim outcrop analogue (Maestrat Basin, E Spain)
Peer reviewedPostprin
Spatial rogue waves in photorefractive SBN crystals
We report on the excitation of large-amplitude waves, with a probability of
around 1% of total peaks, on a photorefractive SBN crystal by using a simple
experimental setup at room temperature. We excite the system using a narrow
Gaussian beam and observe different dynamical regimes tailored by the value and
time rate of an applied voltage. We identify two main dynamical regimes: a
caustic one for energy spreading and a speckling one for peak emergence. Our
observations are well described by a two-dimensional Schr\"odinger model with
saturable local nonlinearity.Comment: 4 pages, 4 figure
Unmasking quality: exploring meanings of health by doing art
This paper arises from a presentation at the âQuality in Healthcareâ symposium at Cumberland Lodge, England, in 2013. MK, CR and SH conceived the paper and led the writing of the manuscript. JF, JL-D, AC, DE contributed substantially to the intellectual content of the paper through providing critical commentary and interpretation. All authors read and approved the final manuscript
Generalized Limits for Parameter Sensitivity via Quantum Ziv-Zakai Bound
We study the generalized limit for parameter sensitivity in quantum
estimation theory considering the effects of repeated and adaptive
measurements. Based on the quantum Ziv-Zakai bound, we derive some lower bounds
for parameter sensitivity when the Hamiltonian of system is unbounded and when
the adaptive measurements are implemented on the system. We also prove that the
parameter sensitivity is bounded by the limit of the minimum detectable
parameter. In particular, we examine several known states in quantum phase
estimation with non-interacting photons, and show that they can not perform
better than Heisenberg limit in a much simpler way with our result.Comment: 8pages, 5 figure
Probing quantum coherence in qubit arrays
We discuss how the observation of population localization effects in
periodically driven systems can be used to quantify the presence of quantum
coherence in interacting qubit arrays. Essential for our proposal is the fact
that these localization effects persist beyond tight-binding Hamiltonian
models. This result is of special practical relevance in those situations where
direct system probing using tomographic schemes becomes infeasible beyond a
very small number of qubits. As a proof of principle, we study analytically a
Hamiltonian system consisting of a chain of superconducting flux qubits under
the effect of a periodic driving. We provide extensive numerical support of our
results in the simple case of a two-qubits chain. For this system we also study
the robustness of the scheme against different types of noise and disorder. We
show that localization effects underpinned by quantum coherent interactions
should be observable within realistic parameter regimes in chains with a larger
number o
Quantum dynamics in photonic crystals
Employing a recently developed method that is numerically accurate within a
model space simulating the real-time dynamics of few-body systems interacting
with macroscopic environmental quantum fields, we analyze the full dynamics of
an atomic system coupled to a continuum light-field with a gapped spectral
density. This is a situation encountered, for example, in the radiation field
in a photonic crystal, whose analysis has been so far been confined to limiting
cases due to the lack of suitable numerical techniques. We show that both
atomic population and coherence dynamics can drastically deviate from the
results predicted when using the rotating wave approximation, particularly in
the strong coupling regime. Experimental conditions required to observe these
corrections are also discussed.Comment: 5 pages, 2 figures Updated with published versio
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