PIONIER: a status report

The visitor instrument PIONIER provides VLTI with improved imaging capabilities and sensitivity. The instrument started routinely delivering scientic data in November 2010, that is less than 12 months after being approved by the ESO Science and Technical Committee. We recall the challenges that had to be tackled to design, built and commission PIONIER. We summarize the typical performances and some astrophysical results obtained so far. We conclude this paper by summarizing lessons learned

Oscillatory Behavior of Critical Amplitudes of the Gaussian Model on a Hierarchical Structure

We studied oscillatory behavior of critical amplitudes for the Gaussian model on a hierarchical structure presented by a modified Sierpinski gasket lattice. This model is known to display non-standard critical behavior on the lattice under study. The leading singular behavior of the correlation length $\xi$ near the critical coupling $K=K_c$ is modulated by a function which is periodic in $\ln|\ln(K_c-K)|$. We have also shown that the common finite-size scaling hypothesis, according to which for a finite system at criticality $\xi$ should be of the order of the size of system, is not applicable in this case. As a consequence of this, the exact form of the leading singular behavior of $\xi$ differs from the one described earlier (which was based on the finite-size scaling assumption).Comment: 9 pages (REVTEX), 2 figures (EPS), Phys. Rev. E (accepted

Single spin-polarised Fermi surface in SrTiO3_3 thin films

The 2D electron gas (2DEG) formed at the surface of SrTiO$_3$(001) has attracted great interest because of its fascinating physical properties and potential as a novel electronic platform, but up to now has eluded a comprehensible way to tune its properties. Using angle-resolved photoemission spectroscopy with and without spin detection we here show that the band filling can be controlled by growing thin SrTiO$_3$ films on Nb doped SrTiO$_3$(001) substrates. This results in a single spin-polarised 2D Fermi surface, which bears potential as platform for Majorana physics. Based on our results it can furthermore be concluded that the 2DEG does not extend more than 2 unit cells into the film and that its properties depend on the amount of SrO$_x$ at the surface and possibly the dielectric response of the system

Wind Energy and the Turbulent Nature of the Atmospheric Boundary Layer

Wind turbines operate in the atmospheric boundary layer, where they are exposed to the turbulent atmospheric flows. As the response time of wind turbine is typically in the range of seconds, they are affected by the small scale intermittent properties of the turbulent wind. Consequently, basic features which are known for small-scale homogeneous isotropic turbulence, and in particular the well-known intermittency problem, have an important impact on the wind energy conversion process. We report on basic research results concerning the small-scale intermittent properties of atmospheric flows and their impact on the wind energy conversion process. The analysis of wind data shows strongly intermittent statistics of wind fluctuations. To achieve numerical modeling a data-driven superposition model is proposed. For the experimental reproduction and adjustment of intermittent flows a so-called active grid setup is presented. Its ability is shown to generate reproducible properties of atmospheric flows on the smaller scales of the laboratory conditions of a wind tunnel. As an application example the response dynamics of different anemometer types are tested. To achieve a proper understanding of the impact of intermittent turbulent inflow properties on wind turbines we present methods of numerical and stochastic modeling, and compare the results to measurement data. As a summarizing result we find that atmospheric turbulence imposes its intermittent features on the complete wind energy conversion process. Intermittent turbulence features are not only present in atmospheric wind, but are also dominant in the loads on the turbine, i.e. rotor torque and thrust, and in the electrical power output signal. We conclude that profound knowledge of turbulent statistics and the application of suitable numerical as well as experimental methods are necessary to grasp these unique features (...)Comment: Accepted by the Journal of Turbulence on May 17, 201

First occurrence of a frog-like batrachian (Amphibia) in the Late Triassic Fleming Fjord Group, central

This research benefited from the GeoBioTec-GeoBioSciences, GeoTechnologies and GeoEngineering NOVA [GeoBioCiências, GeoTecnologias e GeoEngenharias], grant UIDB/04035/2020 by the Fundação para a Ciência e Tecnologia. This study could not have been possible without the team that uncovered this specimen, Farish A Jenkins Jr., William W. Amaral, William R. Downs III, Stephen M. Gatesy, Neil H. Shubin Niels Bonde and Lars B. Clemmensen. We thank Harvard University and Bent Lindow from the Natural History Museum of Denmark. Thanks to Alexandre Guillaume and Vincent Cheng for reviewing and bringing improvements to the original manuscript and Carla Tomás for laboratory support. Alfred Lemierre and an anonymous reviewer are thanked for their comments on the manuscript.During the Triassic, Batrachia diverged into ancestors of frogs (Salientia) and salamanders (Caudata). Fossils of Triassic batrachians are rare and found only in a few outcrops, such as the Middle Sakamena Formation of Madagascar (Induan). Only three Triassic taxa have been described, the two early frogs Triadobatrachus and Czatkiobatrachus and the early salamander Triassurus. Here we describe a right ilium, collected in 1991, attributed to the first batrachian from the Late Triassic Carlsberg Fjord Member (Ørsted Dal Formation, Fleming Fjord Group) in the Jameson Land Basin, located in central East Greenland. The fossil specimen only displays the proximal part of a right ilium, missing its shaft. After a thorough comparison with several clades (lizards, temnospondyls, salamanders and frogs), we consider the specimen as a lissamphibian sharing feature with salientians and anurans: squarish acetabular region, deeply concave acetabular surface, laterally projecting acetabular rim, flat mesial surface. It is the youngest Triassic specimen of Batrachia to date and one of the northernmost of the Late Triassic.publishersversionpublishersversionpublishe

Stark Broadening of Several Ne II, Ne III and O III Spectral Lines for the STARK-B Database

In order to complete Stark broadening data for Ne II, and O III lines, needed for analysis of stellar atmospheres, we determined, within the semiclassical perturbation method, the missing Stark broadening parameters for the broadening by collisions with protons and ionized helium, for 15 Ne II and 5 O III multiplets. Also, electron, proton, and ionized helium impact broadening parameters for an important Ne II multiplet in the visible part of the spectrum, and for three Ne III multiplets, were calculated. The obtained data will be included in the STARK-B database, which is a part of Virtual Atomic and Molecular Data Center

Zeolit kao faktor poboljšanja nekih proizvodnih osobina kod krava muzara

Milk yield and milk chemical composition are largely affected by diet quality. Natural zeolite has been successfully used in livestock production as a feed supplement for some types and categories of domestic animals. This experiment was conducted over a period of 15 months involving Domestic Spotted dairy cattle. The test animals were assigned to three groups, each receiving different levels of supplemental zeolite. The control group comprised cows that received no zeolite supplement. Experimental groups I and II were fed compound feeds supplemented with 4% and 2% zeolite, respectively. The production traits studied included the following milk performance traits: whole lactation length, milk and fat yields over whole lactations, milk and fat yields over standard lactations. The results obtained suggest that zeolite supplementation affects some production traits, depending on the zeolite level present in livestock feed.Kontrolna grupa krava imala je prosečno trajanje laktacije od 312 dana, sa varijacijama od 300 do 360 dana. Ova grupa se po dobijenim rezultatima nalazi između ostale dve grupe krava. Statističke razlike u trajanju celih laktacija među grupama su značajne (P (lt) 0,05). Najniža proizvodnja mleka u celim laktacijama zabeležena je kod krava Kgrupe (6395,20 kg), viša kod krava I-O grupe (6714,13 kg) i najviša kod krava II-O grupe (6934,13 kg) koja je dobijala 2% zeolita preko krmnih smeša. Statističke razlike u proizvodnji mleka u celim laktacijama među grupama su vrlo značajne (P (lt) 0,01). Najmanja prosečna produkcija mleka zabeležena je kod krava K-grupe (6342,33 kg). Znatno veća proizvodnja je bila kod krava koje su dobijale zeolit. Krave I-O grupe dobijale su 4% zeolita i postigle su prosečnu mlečnost od 6690.86 kg. Krave II-O grupe dobijale su 2% zeolita i postigle su najveću prosečnu mlečnost od 6711.80 kg. Krave II-O grupe imale su najveću prosečnu proizvodnju mleka u standardnim laktacijama i najniži koeficijent varijacije među grupama. Statističke razlike u proizvodnji mleka u standardnim laktacijama među grupama su vrlo značajne (P (lt) 0,01). Krave K-grupe imale su najmanju prosečnu priozvodnju mlečne masti u mleku, a krave II-O grupe najveću. Statističke razlike u količini mlečne masti u celim laktacijama među grupama su vrlo značajne (P (lt) 0,01). Takođe su vrlo značajne (P (lt) 0,01) i statističke razlike među grupama u količini mlečne masti u standardnim laktacijama