5,642 research outputs found
Daphnis placida, a new species of Sphinx moth for Guam, U.S.A.
I do not have the submitted version any more. If the published PDF version cannot be deposited, then please remove.This item is licensed under a Creative Commons License (Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)). The attached file is the published version of the article
The phylogeny of Anophelinae revisited: inferences about the origin and classification of Anopheles (Diptera: Culicidae)
© 2015 Royal Swedish Academy of Sciences. "This is the pre-peer reviewed version of the following article: Harbach, R. E. and I. J. Kitching (2016). "The phylogeny of Anophelinae revisited: inferences about the origin and classification of Anopheles (Diptera: Culicidae)." Zoologica Scripta 45(1): 34-47, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/zsc.12137/full. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
3D Photometric Cosmic Shear
Here we present a number of improvements to weak lensing 3D power spectrum
analysis, 3D cosmic shear, that uses the shape and redshift information of
every galaxy to constrain cosmological parameters. We show how photometric
redshift probability distributions for individual galaxies can be directly
included in this statistic with no averaging. We also include the Limber
approximation, considerably simplifying full 3D cosmic shear analysis, and we
investigate its range of applicability. Finally we show the relationship
between weak lensing tomography and the 3D cosmic shear field itself; the steps
connecting them being the Limber approximation, a harmonic-space transform and
a discretisation in wavenumber. Each method has its advantages: 3D cosmic shear
analysis allows straightforward inclusion of all relevant modes, thus ensuring
minimum error bars, and direct control of the range of physical wavenumbers
probed, to avoid the uncertain highly nonlinear regime. On the other hand,
tomography is more convenient for checking systematics through direct
investigation of the redshift dependence of the signal. Finally, for
tomography, we suggest that the angular modes probed should be
redshift-dependent, to recover some of the 3D advantages.Comment: Accepted to MNRAS. 15 pages, 7 figure
A fast empirical method for galaxy shape measurements in weak lensing surveys
We describe a simple and fast method to correct ellipticity measurements of
galaxies from the distortion by the instrumental and atmospheric point spread
function (PSF), in view of weak lensing shear measurements. The method performs
a classification of galaxies and associated PSFs according to measured shape
parameters, and corrects the measured galaxy ellipticites by querying a large
lookup table (LUT), built by supervised learning. We have applied this new
method to the GREAT10 image analysis challenge, and present in this paper a
refined solution that obtains the competitive quality factor of Q = 104,
without any shear power spectrum denoising or training. Of particular interest
is the efficiency of the method, with a processing time below 3 ms per galaxy
on an ordinary CPU.Comment: 8 pages, 6 figures. Metric values updated according to the final
GREAT10 analysis software (Kitching et al. 2012, MNRAS 423, 3163-3208), no
qualitative changes. Associated code available at
http://lastro.epfl.ch/megalu
Ultra-cold mechanical resonators coupled to atoms in an optical lattice
We propose an experiment utilizing an array of cooled micro-cantilevers
coupled to a sample of ultra-cold atoms trapped near a micro-fabricated
surface. The cantilevers allow individual lattice site addressing for atomic
state control and readout, and potentially may be useful in optical lattice
quantum computation schemes. Assuming resonators can be cooled to their
vibrational ground state, the implementation of a two-qubit controlled-NOT gate
with atomic internal states and the motional states of the resonator is
described. We also consider a protocol for entangling two or more cantilevers
on the atom chip with different resonance frequencies, using the trapped atoms
as an intermediary. Although similar experiments could be carried out with
magnetic microchip traps, the optical confinement scheme we consider may
exhibit reduced near-field magnetic noise and decoherence. Prospects for using
this novel system for tests of quantum mechanics at macroscopic scales or
quantum information processing are discussed.Comment: 5 pages, 3 figure
On the Probability Distributions of Ellipticity
In this paper we derive an exact full expression for the 2D probability
distribution of the ellipticity of an object measured from data, only assuming
Gaussian noise in pixel values. This is a generalisation of the probability
distribution for the ratio of single random variables, that is well-known, to
the multivariate case. This expression is derived within the context of the
measurement of weak gravitational lensing from noisy galaxy images. We find
that the third flattening, or epsilon-ellipticity, has a biased maximum
likelihood but an unbiased mean; and that the third eccentricity, or normalised
polarisation chi, has both a biased maximum likelihood and a biased mean. The
very fact that the bias in the ellipticity is itself a function of the
ellipticity requires an accurate knowledge of the intrinsic ellipticity
distribution of the galaxies in order to properly calibrate shear measurements.
We use this expression to explore strategies for calibration of biases caused
by measurement processes in weak gravitational lensing. We find that upcoming
weak lensing surveys like KiDS or DES require calibration fields of order of
several square degrees and 1.2 magnitude deeper than the wide survey in order
to correct for the noise bias. Future surveys like Euclid will require
calibration fields of order 40 square degree and several magnitude deeper than
the wide survey. We also investigate the use of the Stokes parameters to
estimate the shear as an alternative to the ellipticity. We find that they can
provide unbiased shear estimates at the cost of a very large variance in the
measurement. The python code used to compute the distributions presented in the
paper and to perform the numerical calculations are available on request.Comment: 24 pages, 18 figures, 2 Tables. Accepted for publication in Monthly
Notices of the Royal Astronomical Society Main Journa
Generation of amplitude-squeezed light from a room-temperature Fabry-Perot semiconductor laser
Amplitude-squeezed light with intensity fluctuations 29% below the standard quantum limit (SQL) is produced from a pump-suppressed room-temperature semiconductor laser, corresponding to 41% below the SQL after correction for detection efficiency. Excess noise, which degrades the observed squeezing, appears to be associated with the presence of weak longitudinal side modes
The phylogenetic conundrum of Lutzia(Diptera: Culicidae: Culicini): a cautionary account of conflict and support
This is an open access article, available to all readers online, published under a creative commons licensing (https://creativecommons.org/licenses/by/4.0/). This document is the author's submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it
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