Romanian Academy

About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.

Zooplankton community response to enhanced turbulence generated by water-level decrease in Lake Balaton, the largest shallow lake in Central Europe

Abstract: During the unusually long European drought between 2000 and 2003, the water level of the large and shallow Lake Balaton, Hungary (area 5 596 km2, mean depth 5 3.25 m), decreased by 28%. Although food availability for zooplankton remained unchanged, and the fish stock declined more than the water mass, the density of populations of several planktonic rotifers, cladocerans, calanoid copepodes, and veligers decreased by 60–90% simultaneously with the water-level decrease and regenerated only after the drought. The generally strong turbulence of the lake was intensified during the four consecutive years of low water, as verified by instrumental monitoring of the turbulence intensity and by the estimation of the turbulent kinetic-energy dissipation rate. In our tank experiments, turbulence conditions similar to those that existed in the lake during low water were simulated, but mineral suspended material was minimized and food was regularly resupplied. Under these experimental conditions, zooplankton taxa showing the highest mortality were the same as those that were most susceptible in situ. Increased turbulence coupled with the water-level decrease is especially unfavorable for rotifer Keratella, the cladoceran Daphnia, Bosmina, and copepodit and adult stages of the calanoid copepod Eudiaptomus gracilis in this lake.

Generalized (anti) Yetter-Drinfeld modules as components of a braided T-category

Abstract: If H is a Hopf algebra with bijective antipode and α, β ∈ Aut Hopf (H), we introduce a category $$_H \mathcal{Y}\mathcal{D}^H (\alpha ,\beta )$$ , generalizing both Yetter-Drinfeld modules and anti-Yetter-Drinfeld modules. We construct a braided T-category $$\mathcal{Y}\mathcal{D}(H)$$ having all the categories $$_H \mathcal{Y}\mathcal{D}^H (\alpha ,\beta )$$ as components, which, if H is finite dimensional, coincides with the representations of a certain quasitriangular T-coalgebra DT(H) that we construct. We also prove that if (α, β) admits a so-called pair in involution, then $$_H \mathcal{Y}\mathcal{D}^H (\alpha ,\beta )$$ is isomorphic to the category of usual Yetter-Drinfeld modules $$_H \mathcal{Y}\mathcal{D}^H $$ .

Equidistribution Results for Singular Metrics on Line Bundles

Abstract: Let L be a holomorphic line bundle with a positively curved singular Hermitian metric over a complex manifold X. One can define naturally the sequence of Fubini-Study currents associated to the space of square integrable holomorphic sections of the p-th tensor powers of L. Assuming that the singular set of the metric is contained in a compact analytic subset of X and that the logarithm of the Bergman kernel function associated to the p-th tensor power of L (defined outside the singular set) grows like o(p) as p tends to infinity, we prove the following: 1) the k-th power of the Fubini-Study currents converge weakly on the whole X to the k-th power of the curvature current of L. 2) the expectations of the common zeros of a random k-tuple of square integrable holomorphic sections converge weakly in the sense of currents to to the k-th power of the curvature current of L. Here k is so that the codimension of the singular set of the metric is greater or equal as k. Our weak asymptotic condition on the Bergman kernel function is known to hold in many cases, as it is a consequence of its asymptotic expansion. We also prove it here in a quite general setting. We then show that many important geometric situations (singular metrics on big line bundles, Kaehler-Einstein metrics on Zariski-open sets, artihmetic quotients) fit into our framework.