Two new charismatic Pristimantis species (Anura: Craugastoridae) from the tepuis of “The Lost World” (Pantepui region, South America)

Two new colourful species of direct-developing frogs of the genus Pristimantis are described from the summit of two isolated tepuis (sandstone table mountains) in the Eastern Pantepui District of the Guiana Shield highlands. Pristimantis jamescameroni sp. nov. is described from the summit of Aprada-tepui from 2557-2571 m elevation, and P. imthurni sp. nov. is described from the summit of Ptaritepui at 2471 m elevation. Both species share the absence of a differentiated tympanic membrane and external tympanic annulus (but presence of tiny pharyngeal ostia), the presence of nuptial pads in males, and the presence of lateral fringes on fingers and toes, a combination of characters that immediately distinguishes them from all other known Pantepui congeners. The two new species are morphologically similar to each other and are phylogenetically closely related, but they can be distinguished based on colour pattern and morphological characters such as head proportions, dorsal skin texture, and condition of the supratympanic fold. The IUCN conservation status of the new species is considered as Endangered (EN) owing to their apparent very restricted ranges. The number of described Pristimantis species occurring exclusively on tepui (and faunistically related granitic mountains) summits and upper slopes now reaches eleven

Comment on: "Measuring a Photonic Qubit without Destroying It"

Recently, Pryde et al reported the demonstration of a quantum non-demolition scheme for single-photon polarization states with linear optics and projective measurements [Phys. Rev. Lett. 92, 190402 (2004)]. Here, we argue that their interpretation of the experiment is inconsistent with the fidelity measure they use.Comment: one page, no figure

A Quantum Rosetta Stone for Interferometry

Heisenberg-limited measurement protocols can be used to gain an increase in measurement precision over classical protocols. Such measurements can be implemented using, e.g., optical Mach-Zehnder interferometers and Ramsey spectroscopes. We address the formal equivalence between the Mach-Zehnder interferometer, the Ramsey spectroscope, and the discrete Fourier transform. Based on this equivalence we introduce the ``quantum Rosetta stone'', and we describe a projective-measurement scheme for generating the desired correlations between the interferometric input states in order to achieve Heisenberg-limited sensitivity. The Rosetta stone then tells us the same method should work in atom spectroscopy.Comment: 8 pages, 4 figure

Learning short multivariate time series models through evolutionary and sparse matrix computation

Multivariate time series (MTS) data are widely available in different fields including medicine, finance, bioinformatics, science and engineering. Modelling MTS data accurately is important for many decision making activities. One area that has been largely overlooked so far is the particular type of time series where the data set consists of a large number of variables but with a small number of observations. In this paper we describe the development of a novel computational method based on Natural Computation and sparse matrices that bypasses the size restrictions of traditional statistical MTS methods, makes no distribution assumptions, and also locates the associated parameters. Extensive results are presented, where the proposed method is compared with both traditional statistical and heuristic search techniques and evaluated on a number of criteria. The results have implications for a wide range of applications involving the learning of short MTS models

Deterministic-statistical model coupling in a DSS for river-basin management

This paper presents a method for appropriate coupling of deterministic and statistical models. In the decision-support system for the Elbe river, a conceptual rainfall-runoff model is used to obtain the discharge statistics and corresponding average number of flood days, which is a key input variable for a rule-based model for floodplain vegetation. The required quality of the discharge time series cannot be determined by a sensitivity analysis because a deterministic model is linked to a statistical model. To solve the problem, artificial discharge time series are generated that mimic the hypothetical output of rainfall-runoff models of different accuracy. The results indicate that a feasible calibration of the rainfall-runoff model is sufficient to obtain consistency with the vegetation model in view of its sensitivity to changes in the number of flood days in the floodplains

The influence of forward-scattered light in transmission measurements of (exo)planetary atmospheres

[Abridged] The transmission of light through a planetary atmosphere can be studied as a function of altitude and wavelength using stellar or solar occultations, giving often unique constraints on the atmospheric composition. For exoplanets, a transit yields a limb-integrated, wavelength-dependent transmission spectrum of an atmosphere. When scattering haze and/or cloud particles are present in the planetary atmosphere, the amount of transmitted flux not only depends on the total optical thickness of the slant light path that is probed, but also on the amount of forward-scattering by the scattering particles. Here, we present results of calculations with a three-dimensional Monte Carlo code that simulates the transmitted flux during occultations or transits. For isotropically scattering particles, like gas molecules, the transmitted flux appears to be well-described by the total atmospheric optical thickness. Strongly forward-scattering particles, however, such as commonly found in atmospheres of Solar System planets, can increase the transmitted flux significantly. For exoplanets, such added flux can decrease the apparent radius of the planet by several scale heights, which is comparable to predicted and measured features in exoplanet transit spectra. We performed detailed calculations for Titan's atmosphere between 2.0 and 2.8 micron and show that haze and gas abundances will be underestimated by about 8% if forward-scattering is ignored in the retrievals. At shorter wavelengths, errors in the gas and haze abundances and in the spectral slope of the haze particles can be several tens of percent, also for other Solar System planetary atmospheres. We also find that the contribution of forward-scattering can be fairly well described by modelling the atmosphere as a plane-parallel slab.Comment: Icarus, accepted for publicatio

Communicating continuous quantum variables between different Lorentz frames

We show how to communicate Heisenberg-limited continuous (quantum) variables between Alice and Bob in the case where they occupy two inertial reference frames that differ by an unknown Lorentz boost. There are two effects that need to be overcome: the Doppler shift and the absence of synchronized clocks. Furthermore, we show how Alice and Bob can share Doppler-invariant entanglement, and we demonstrate that the protocol is robust under photon loss.Comment: 4 pages, 1 figur

Information gap for classical and quantum communication in a Schwarzschild spacetime

Communication between a free-falling observer and an observer hovering above the Schwarzschild horizon of a black hole suffers from Unruh-Hawking noise, which degrades communication channels. Ignoring time dilation, which affects all channels equally, we show that for bosonic communication using single and dual rail encoding the classical channel capacity reaches a finite value and the quantum coherent information tends to zero. We conclude that classical correlations still exist at infinite acceleration, whereas the quantum coherence is fully removed.Comment: 5 pages, 4 figure