Species population genetics could be an important factor explaining variation in clade species richness. Here, we use newly generated amplified fragment length polymorphism (AFLP) data to test ...whether five pairs of sister clades of Costa Rican orchids that differ greatly in species richness also differ in average neutral genetic differentiation within species, expecting that if the strength of processes promoting differentiation within species is phylogenetically heritable, then clades with greater genetic differentiation should diversify more. Contrary to expectation, neutral genetic differentiation does not correlate directly with total diversification in the clades studied. Neutral genetic differentiation varies greatly among species and shows no heritability within clades. Half of the variation in neutral genetic differentiation among populations can be explained by ecological variables, and species-level traits explain the most variation. Unexpectedly, we find no isolation by distance in any species, but genetic differentiation is greater between populations occupying different niches. This pattern corresponds with those observed for microscopic eukaryotes and could reflect effective widespread dispersal of tiny and numerous orchid seeds. Although not providing a definitive answer to whether population genetics processes affect clade diversification, this work highlights the potential for addressing new macroevolutionary questions using a comparative population genetic approach.
The article presents a simple alternative approach to pulse shaping filters with ISI-free matched (white noise case) and unmatched filter properties. A Nyquist (1928) 1 filter in closed form is ...proved to be ISI-free with or without matched filtering when its complex transfer function is derived from an initially given Nyquist 1 filter. The simplicity of the application of this procedure is illustrated by an example.
The search for new crystalline host materials for the usage in lasers emitting in the eye-safe spectral range of 1.5–1.6 µm is an important task. The aim of this work was to study the growth ...technique, spectroscopic properties and laser characteristics of new active media – crystals Er
3+
,Yb
3+
:Ca
2
RE
2
(BO
3
)
4
(RE=Y, Gd).
Calcium-yttrium Er
3+
,Yb
3+
:Ca
3
Y
2
(BO
3
)
4
(CYB) and calcium-gadolinium Er
3+
,Yb
3+
: Ca
2
Gd
2
(BO
3
)
4
(CGB) oxoborate crystals co-doped with erbium and ytterbium ions were investigated. Polarized absorption and emission cross-section spectra were determined. The lifetimes of
4
I
11/2
and
4
I
13/2
energy levels of Er
3+
ions were measured and ytterbium-erbium energy transfer efficiencies were estimated. The calculation of the gain cross-section spectra was performed. By using of Er
3+
,Yb
3+
: Ca
2
RE
2
(BO
3
)
4
(RE=Y, Gd) crystals the laser performance was realized, for the first time to the best of our knowledge. The laser characteristics were studied in a quasi-CW (QCW) laser operation.
The wide band with a peak at the wavelength of 976 nm is observed in the absorption spectra of both crystals. This peak coincides with the emission wavelength of the pump laser diodes for Yb-doped active media. The maximum value of absorption cross-section was 1.7 × 10
–20
cm
2
for polarization
E
//
b
for both crystals. The lifetimes of the upper laser level
4
I
13/2
of Er
3+
ions were 580 ± 30 μs and 550 ± 30 μs for Er,Yb:CYB and Er,Yb:CGB crystals, respectively. The energy transfer efficiencies from ytterbium to erbium ions for an Er,Yb:CYB and Er,Yb:CGB crystals were 94 % and 96 %, respectively. According to gain spectrum of the Er,Yb:CYB crystal the gain band peak is centered at the wavelength of 1530 nm. The maximum QCW output power was 0.5 W with slope efficiency of 13 % regarding to absorbed pump power for an Er,Yb: CYB crystal. The laser beam parameter M
2
did not exceed < 1.5.
Based on the obtained results, it can be concluded that these crystals are promising active media for lasers emitting in the spectral range of 1.5–1.6 μm for the usage in laser rangefinder and laser-induced breakdown spectroscopy systems, and LIDARs.
New STAR measurements of two- and four-particle (c2{4}) azimuthal angle correlations are reported for p+Au collisions at 200 GeV and d+Au collisions from 19.6 to 200 GeV. A negative c2{4}, consistent ...with collective anisotropic flow, is observed in high multiplicity d+Au events at 62.4 and 200 GeV where the statistical significance of the data allows an analysis. A template fitting method, employed to subtract non-flow contributions to the two-particle correlations, allows the extraction of the anisotropy coefficients (ν2) for these systems at their respective energies. The ν2 results for different energies show a common dependence on the charged particle multiplicity density (〈dNch/dη〉), which provide important insight on the nature of collective behavior in small collision systems.
The Nyquist (1928) 1 filters (NFls) with both nonlinear phase response and amplitude response of nonspecified symmetry are investigated. It is shown that one of the filter's responses (amplitude or ...phase) can be chosen almost arbitrary. The second one is then derived from the condition of zero intersymbol interference (ISI) in data transmission synchronous systems. As a specific application of the presented theory, a simple procedure for calculating NFl's with ISI-free matched and unmatched filter properties is proposed.
Crystal with composition Li2Zn2(MoO4)3 doped with 0.7 at.% Yb (Yb:LiZnMo), with high optical quality and a length of a few cm is grown from the flux using Li2MoO4 as a solvent. Yb:LiZnMo is ...orthorombic (sp. gr. Pnma, a = 5.0843 Å, b = 10.4927 Å, c = 17.6742 Å, Z = 4). Polarized Raman spectra are studied for this crystal; the most intense band is observed at 898 cm−1. The absorption, stimulated-emission and gain cross-sections of Yb3+ ions are determined for the principal light polarizations, E || a, b, c. The maximum σSE = 6.6 × 10−21 cm2 at 1011 nm for E || b. The gain bandwidth for Yb:LiZnMo is up to ~50 nm. The radiative lifetime of the Yb3+ ions is 1.55 ms. The Yb:LiZnMo crystals are very promising for broadly tunable lasers.
Round table debate “Transformation of political values in the EU: pros and cons” was held on February 13 2017 on the Faculty of the humanities and social sciences of Peoples’ Friendship University of ...Russia (RUDN University). The “Round-table” debate has been realized in the frame of the project “Transformation of the social and political values: the EU practice” (project number: 575361-EPP-1-2016-1-RU-EPPJMO-MODULE), Erasmus+ Jean Monnet Actions. Jean Monnet Module “Transformation of the social and political values: the EU practice”.
Abstract
Vanadium dioxide (VO
2
) is a material with a metal-insulator phase transition. We report a way of application of VO
2
thin films as functional elements of reconfigurable parallel plate ...waveguide array (PPWA). The PPWA presented here is designed to work in X, K
u
and K bands. A transmission coefficient of the array with VO
2
elements can be altered using temperature by more than 10 dB across the entire experimentally studied frequency range. We demonstrate a method of design and manufacturing of the PPWA. The PPWA may be used as a basic component in more advanced reconfigurable devices.
Vanadium dioxide (VO2) is a material with a metal-insulator phase transition. We report a way of application of VO2 thin films as functional elements of reconfigurable parallel plate waveguide array ...(PPWA). The PPWA presented here is designed to work in X, Ku and K bands. A transmission coefficient of the array with VO2 elements can be altered using temperature by more than 10 dB across the entire experimentally studied frequency range. We demonstrate a method of design and manufacturing of the PPWA. The PPWA may be used as a basic component in more advanced reconfigurable devices.
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