13,400 research outputs found
Two species? - Limits of the species concepts in the pygmy grasshoppers of the Tetrix bipunctata complex (Orthoptera, Tetrigidae)
Today, integrative taxonomy is often considered the gold standard when it comes to species recognition and delimitation. Using the Tetrix bipunctata complex, we here present a case where even integrative taxonomy may reach its limits. The Tetrix bipunctata complex consists of two morphs, bipunctata and kraussi, which are easily distinguished by a single character, the length of the hind wing. Both morphs are widely distributed in Europe and reported to occur over a large area in sympatry, where they occasionally may live also in syntopy. The pattern has led to disparate classifications, as on the one extreme, the morphs were treated merely as forms or subspecies of a single species, on the other, as separate species. For this paper, we re-visited the morphology by using multivariate ratio analysis (MRA) of 17 distance measurements, checked the distributional data based on verified specimens and examined micro-habitat use. We were able to confirm that hind wing length is, indeed, the only morphological difference between bipunctata and kraussi. We were also able to exclude a mere allometric scaling. The morphs are, furthermore, largely sympatrically distributed, with syntopy occurring regularly. However, a microhabitat niche difference can be observed. Ecological measurements in a shared habitat confirm that kraussi prefers a drier and hotter microhabitat, which possibly also explains the generally lower altitudinal distribution. Based on these results, we can exclude classification as subspecies, but the taxonomic classification as species remains unclear. Even with different approaches to classify the Tetrix bipunctata complex, this case is, therefore, not settled. We recommend continuing to record kraussi and bipunctata separately
Influence of the pion-nucleon interaction on the collective pion flow in heavy ion reactions
We investigate the influence of the real part of the in-medium pion optical
potential on the pion dynamics in intermediate energy heavy ion reactions at 1
GeV/A. For different models, i.e. a phenomenological model and the
--hole model, a pionic potential is extracted from the dispersion
relation and used in Quantum Molecular Dynamics calculations. In addition with
the inelastic scattering processes we thus take care of both, real and
imaginary part of the pion optical potential. A strong influence of the real
pionic potential on the pion in-plane flow is observed. In general such a
potential has the tendency to reduce the anticorrelation of pion and nucleon
flow in non-central collisions.Comment: 12 pages Latex, 4 PS-figure
Photoelectron spectromicroscopy at chalcopyrite films
CuInSe2 films were prepared by MBE on GaAs 111 A substrates. ZnSe and ZnO are subsequently deposited in situ by MOMBE. Interface parameters like band offsets and morphology are studied by X ray photoelectron spectroscopy XPS and Low energy electron diffraction LEED . Spectroscopic XPEEM X ray Photo electron emission microscopy at the U49 2 PGM2 beamline at BESSY was used to investigate the lateral homogenity of the interface. After annealing in situ a lateral inhomogenious In diffusion is observed into the ZnSe ZnO interfac
Biaxial order parameter in the homologous series of orthogonal bent-core smectic liquid crystals
The fundamental parameter of the uniaxial liquid crystalline state that governs nearly all of its physical properties is the primary orientational order parameter (S) for the long axes of molecules with respect to the director. The biaxial liquid crystals (LCs) possess biaxial order parameters depending on the phase symmetry of the system. In this paper we show that in the first approximation a biaxial orthogonal smectic phase can be described by two primary order parameters: S for the long axes and C for the ordering of the short axes of molecules. The temperature dependencies of S and C are obtained by the Haller's extrapolation technique through measurements of the optical birefringence and biaxiality on a nontilted polar antiferroelectric (Sm-APA) phase of a homologous series of LCs built from the bent-core achiral molecules. For such a biaxial smectic phase both S and C, particularly the temperature dependency of the latter, are being experimentally determined. Results show that S in the orthogonal smectic phase composed of bent cores is higher than in Sm-A calamatic LCs and C is also significantly large
Extremely Metal-Poor Stars. VII. The Most Metal-Poor Dwarf, CS 22876-032
We report high-resolution, high-signal-to-noise, observations of the
extremely metal-poor double-lined spectroscopic binary CS 22876-032. The system
has a long period : P = 424.7 0.6 days. It comprises two main sequence
stars having effective temperatures 6300 K and 5600 K, with a ratio of
secondary to primary mass of 0.89 0.04. The metallicity of the system is
[Fe/H] = -3.71 0.11 0.12 (random and systematic errors) -- somewhat
higher than previous estimates. We find [Mg/Fe] = 0.50, typical of values of
less extreme halo material. [Si/Fe], [Ca/Fe], and [Ti/Fe], however, all have
significantly lower values, ~ 0.0-0.1, suggesting that the heavier elements
might have been underproduced relative to Mg in the material from which this
object formed. In the context of the hypothesis that the abundance patterns of
extremely metal-poor stars are driven by individual enrichment events and the
models of Woosley and Weaver (1995), the data for CS 22876-032 are consistent
with its having been enriched by a zero-metallicity supernova of mass 30
M. As the most metal-poor near-main-sequence-turnoff star currently
known, the primary of the system has the potential to strongly constrain the
primordial lithium abundance. We find A(Li) (= log(N(Li)/N(H)) + 12.00) = 2.03
0.07, which is consistent with the finding of Ryan et al. (1999) that for
stars of extremely low metallicity A(Li) is a function of [Fe/H].Comment: 27 pages, 9 figures, accepted for publication in The Astrophysical
Journal, Sept. 1, 2000 issu
Nitrogen retention and plant uptake on a highly weathered central Amazonian Ferralsol amended with compost and charcoal.
Inspired by the sustained fertility of anthropogenic Terra Preta soils in the central Amazon Basin, we studied the effect of charcoal as soil amendment
Hypothesis testing for an entangled state produced by spontaneous parametric down conversion
Generation and characterization of entanglement are crucial tasks in quantum
information processing. A hypothesis testing scheme for entanglement has been
formulated. Three designs were proposed to test the entangled photon states
created by the spontaneous parametric down conversion. The time allocations
between the measurement vectors were designed to consider the anisotropic
deviation of the generated photon states from the maximally entangled states.
The designs were evaluated in terms of the p-value based on the observed data.
It has been experimentally demonstrated that the optimal time allocation
between the coincidence and anti-coincidence measurement vectors improves the
entanglement test. A further improvement is also experimentally demonstrated by
optimizing the time allocation between the anti-coincidence vectors. Analysis
on the data obtained in the experiment verified the advantage of the
entanglement test designed by the optimal time allocation.Comment: 7 figures, 9 pages. This paper is revised for increasing the
readership for experimentalists. Hence, the mathematical part is moved to a
new manuscript quant-ph/060802
Corte e carbonização como uma alternativa ao corte e queima: estudos na Amazônia.
Neste capítulo são apresentados vários estudos realizados em Manaus cujo principal objetivo foi verificar o efeito da aplicação de carvão vegetal no manejo do Latossolo Amarelo (xanthic Ferralsol) na terra firme em Manaus - Brasil. Os estudos foram conduzidos na Estação Experimental da Embrapa Amazônia Ocidental no km 30 da Rodovia AM-010. Também é descrito uma forma de manejo indígena da fertilidade do solo pela queima e uso de fontes orgânica
Minimax mean estimator for the trine
We explore the question of state estimation for a qubit restricted to the
- plane of the Bloch sphere, with the trine measurement. In our earlier
work [H. K. Ng and B.-G. Englert, eprint arXiv:1202.5136[quant-ph] (2012)],
similarities between quantum tomography and the tomography of a classical die
motivated us to apply a simple modification of the classical estimator for use
in the quantum problem. This worked very well. In this article, we adapt a
different aspect of the classical estimator to the quantum problem. In
particular, we investigate the mean estimator, where the mean is taken with a
weight function identical to that in the classical estimator but now with
quantum constraints imposed. Among such mean estimators, we choose an optimal
one with the smallest worst-case error-the minimax mean estimator-and compare
its performance with that of other estimators. Despite the natural
generalization of the classical approach, this minimax mean estimator does not
work as well as one might expect from the analogous performance in the
classical problem. While it outperforms the often-used maximum-likelihood
estimator in having a smaller worst-case error, the advantage is not
significant enough to justify the more complicated procedure required to
construct it. The much simpler adapted estimator introduced in our earlier work
is still more effective. Our previous work emphasized the similarities between
classical and quantum state estimation; in contrast, this paper highlights how
intuition gained from classical problems can sometimes fail in the quantum
arena.Comment: 18 pages, 3 figure
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