174 research outputs found
Combining Full-Shape and BAO Analyses of Galaxy Power Spectra: A 1.6% CMB-independent constraint on H0
We present cosmological constraints from a joint analysis of the pre- and
post-reconstruction galaxy power spectrum multipoles from the final data
release of the Baryon Oscillation Spectroscopic Survey (BOSS). Geometric
constraints are obtained from the positions of BAO peaks in reconstructed
spectra, analyzed in combination with the unreconstructed spectra in a
full-shape (FS) likelihood using a joint covariance matrix, giving stronger
parameter constraints than FS-only or BAO-only analyses. We introduce a new
method for obtaining constraints from reconstructed spectra based on a
correlated theoretical error, which is shown to be simple, robust, and
applicable to any flavor of density-field reconstruction. Assuming CDM
with massive neutrinos, we analyze data from two redshift bins
and obtain constraints on the Hubble
constant , using only a single prior on the current baryon density
from Big Bang Nucleosynthesis (BBN) and no knowledge of the power
spectrum slope . This gives , with the inclusion of BAO
data sharpening the measurement by , representing one of the strongest
current constraints on independent of cosmic microwave background data.
Restricting to the best-fit slope from Planck (but without additional
priors on the spectral shape), we obtain a measurement of . We find strong constraints on the
cosmological parameters from a joint analysis of the FS, BAO, and Planck data.
This sets new bounds on the sum of neutrino masses (at confidence) and the effective number of
relativistic degrees of freedom , though
contours are not appreciably narrowed by the inclusion of BAO data.Comment: 42 pages, 12 figures, accepted by JCAP, likelihoods available at
https://github.com/Michalychforever/lss_montepython (minor typo corrected
Analysis of diet of piscivorous fishes in Bovan, Gruža and Šumarice Reservoir, Serbia
Diet of adult pikeperch Sander lucioperca, Eurasian perch Perca fluviatilis, northern pike Esox lucius and European catfish Silurus glanis as top predators in aquatic ecosystems in Serbia was investigated during 2011, in order to understand their relationship to their prey and to investigate their food consumption, feeding and assimilation rate, cannibalism, and habitat segregation. Northern pike, Eurasian perch, pikeperch and European catfish were collected in three reservoirs in Serbia. Prey items that were found in all four species included fish, mollusks, insect larvae and crustaceans. A total of 11 taxonomic groups were found, but they were not all represented as a prey in all four species. Eurasian perch were present in the diet of all four predatory fish species, mollusks were recorded only in that of European catfish. Roach Rutilus rutilus and bleak Alburnus alburnus were prey to all species, except northern pike. Chub Squalius cephalus, bream Brama brama and Gammaridae were found only in stomach of pikeperch. Analysis of similarity showed that difference for diet between predatory fish species was significant for their due to significant differences existing between northern pike and pikeperch and northern pike and Eurasian perch
Comparative analysis of numerical computational techniques for determination of the wind turbine aerodynamic performances
The purpose of this paper is to explore and define an adequate numerical setting for the computation of aerodynamic performances of wind turbines of various shapes and sizes, which offers the possibility of choosing a suitable approach of minimal complexity for the future research. Here, mechanical power, thrust, power coefficient, thrust coefficient, pressure coefficient, pressure distribution along the blade, relative velocity contoure, at different wind speeds and streamlines were considered by two different methods: the blade element momentum and CFD, within which three different turbulence models were analyzed. The estimation of the mentioned aerodynamic performances was carried out on two different wind turbine blades. The obtained solutions were compared with the experimental and nominal (up-scaled) values, available in the literature. Although the flow was considered as steady, a satisfactory correlation between numerical and experimental results was achieved. The comparison between results also showed, the significance of selection, regarding the complexity and geometry of the analyzed wind turbine blade, the most appropriate numerical approach for computation of aerodynamic performances
Dynamical screening of the Coulomb interaction for two confined electrons in a magnetic field
We show that a difference in time scales of vertical and lateral dynamics
permits one to analyze the problem of interacting electrons confined in an
axially symmetric three-dimensional potential with a lateral oscillator
confinement by means of the effective two-dimensional Hamiltonian with a
screened Coulomb interaction. Using an adiabatic approximation based on
action-angle variables, we present solutions for the effective charge of the
Coulomb interaction (screening) for a vertical confinement potential simulated
by parabolic, square, and triangular wells. While for the parabolic potential
the solution for the effective charge is given in a closed anlytical form, for
the other cases similar solutions can be easily calculated numerically.Comment: 10 pages, 6 figure
Silencing of germacrene A synthase genes reduces guaianolide oxalate content in <i>Cichorium intybus</i> L.
Scardinius knezevici Bianco & Kottelat, 2005 and Alburnus scoranza Bonaparte, 1845: New species of ichthyofauna of Serbia and the Danube basin
Research into the ichthyofauna of the Vlasina Lake reservoir in south Serbia, which is part of the Danube basin, was carried out in 1993, 40 years after its formation. The results of the research reveal the presence of several species of fish belonging to the Adriatic and Aegean basin, such as Alburnus albidus, Rutilus basak, Scardinius graecus and Pachychilon macedonicus. These findings are of great importance from the aspect of conservation, because the species Scardinius graecus and Alburnus albidus are on the European list of endangered fish species. In the latest study of the Vlasina Lake reservoir ichthyofauna (70 years after its formation), the above-mentioned species were not found. However, the presence of naturalized populations of two species from the Adriatic basin were confirmed: Scardinius knezevici and Alburnus scoranza. These findings represent the first known areal expansion of these species, which are new to the ichthyofauna of Serbia, from the Adriatic into the Danube (Black Sea) basin.[Acknowledgments. The present work was supported by the Ministry of Education and Science of the Republic of Serbia (Projects No. 43002 and 173025).
Silencing of germacrene A synthase genes reduces guaianolide oxalate content in <i>Cichorium intybus</i> L.
Chicory (Cichorium intybus L.) is a medicinal and industrial plant from the Asteraceae family that produces a variety of sesquiterpene lactones (STLs), most importantly bitter guaianolides: lactucin, lactucopicrin and 8-deoxylactucin as well as their modified forms such as oxalates. These compounds have medicinal properties; however, they also hamper the extraction of inulin – a very important food industry product from chicory roots. The first step in guaianolide biosynthesis is catalyzed by germacrene A synthase (GAS) which in chicory exists in two isoforms – GAS long (encoded by CiGASlo) and GAS short (encoded by CiGASsh). AmiRNA silencing was used to obtain plants with reduced GAS gene expression and level of downstream metabolites, guaianolide-15-oxalates, as the major STLs in chicory. This approach could be beneficial for engineering new chicory varieties with varying STL content, and especially varieties with reduced bitter compounds more suitable for inulin production
Modeling Galaxies in Redshift Space at the Field Level
We develop an analytical forward model based on perturbation theory to
predict the redshift-space galaxy overdensity at the field level given a
realization of the initial conditions. We find that the residual noise between
the model and simulated galaxy density has a power spectrum that is white on
large scales, with size comparable to the shot noise. In the mildly nonlinear
regime, we see a correction to the noise power spectrum,
corresponding to larger noise along the line of sight and on smaller scales.
The parametric form of this correction has been predicted on theoretical
grounds before, and our simulations provide important confirmation of its
presence. We have also modeled the galaxy velocity at the field-level and
compared it against simulated galaxy velocities, finding that about of
the galaxies are responsible for half of the rms velocity residual for our
simulated galaxy sample.Comment: 21 pages, 12 figures. Code available at
https://github.com/mschmittfull/per
Optimal airfoil design and wing analysis for solar-powered high altitude platform station
The ability of flying continuously over prolonged periods of time has become target of numerous research studies performed in recent years in both the fields of civil aviation and unmanned drones. High altitude platform stations are aircrafts that can operate for an extended period of time at altitudes 17 km above sea level and higher. The aim of this paper is to design and optimize a wing for such platforms and computationally investigate its aerodynamic performance. For that purpose, two-objective genetic algorithm, class shape transformation and panel method were combined and used to define different airfoils with the highest lift-to-drag ratio and maximal lift coefficient. Once the most suitable airfoil was chosen, polyhedral half-wing was modeled and its aerodynamic performances were estimated using the CFD approach. Flow simulations of transitional flow at various angles-of-attack were realized in ANSYS FLUENT and various quantitative and qualitative results are presented, such as aerodynamic coefficient curves and flow visualizations. In the end, daily mission of the aircraft is simulated and its energy requirement is estimated. In order to be able to cruise above Serbia in July, an aircraft weighing 150 kg must accumulate 17 kWh of solar energy per day
Constraints on Multi-Field Inflation from the BOSS Galaxy Survey
We use redshift-space galaxy clustering data from the BOSS survey to
constrain local primordial non-Gaussianity (LPNG). This is of particular
importance due to the consistency relations, which imply that a detection of
LPNG would rule out all single-field inflationary models. Our constraints are
based on the consistently analyzed redshift-space galaxy power spectra and
bispectra, extracted from the public BOSS data with optimal window-free
estimators. We use a complete perturbation theory model including all one-loop
power spectrum corrections generated by LPNG. Our constraint on the amplitude
of the local non-Gaussian shape is at
68\%\,CL, yielding no evidence for primordial non-Gaussianity. The addition of
the bispectrum tightens the constraints from BOSS by
, and allows breaking of degeneracies with non-Gaussian galaxy bias.
These results set the stage for the analysis of future surveys, whose larger
volumes will yield significantly tighter constraints on LPNG.Comment: 20 pages, 5 figure
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