Bulgarian Academy of Sciences

About: Bulgarian Academy of Sciences is a government organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Coupling constant & Catalysis. The organization has 17989 authors who have published 36276 publications receiving 642820 citations. The organization is also known as: Bulgarian Academy of Sciences，簡稱：BAS & Balgarska Akademiya na Naukite.

Measurement of the Υ(1S), Υ(2S), and Υ(3S) Polarizations in pp Collisions at s√=7 TeV

Abstract: The polarizations of the Υ(1S), Υ(2S), and Υ(3S) mesons are measured in proton-proton collisions at √s=7 TeV, using a data sample of Υ(nS)→μ^+μ^- decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb^(-1). The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λ_ϑ, λ_φ, and λ_(ϑφ), as well as the frame-invariant quantity λ˜, are presented as a function of the Υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.

Analytical model for the growth of the coastal internal boundary layer during onshore flow

Abstract: A model of near-neutral and convective steady-state internal boundary layer evolution is presented. the model deals with the internal boundary layer that forms over land in coastal and lake areas during onshore winds. Near the ground, the growth of the internal boundary layer is controlled by friction velocity in accordance with surface layer theory. Farther downwind, the growth is determined by the atmospheric stability and friction velocity within the internal boundary layer, and the temperature gradient in the air above. the wind profile inside the internal boundary layer is assumed to follow Obukhov similarity theory. an expression for the strength of the inversion that caps the layer is derived and used in the model. A comparison is carried out with independent experimental observations of internal boundary layer growth in the sea-land transition. Kinematic heat flux through the top of the internal boundary layer is described by the formulation − h = 0.2s + 2.5 uT/gh + the Zilitinkevich correction. the terms 0.2s and 2.5uT/gh account for convective and mechanical turbulence, respectively, and the Zilitinkevich correction is a turbulent kinetic-energy storage term that ensures finite growth rate of the internal boundary layer near the ground. the relative importance of mechanical and convective turbulence as well as the Zilitinkevich correction is discussed. the Zilitinkevich correction dominates the growth process of the internal boundary layer when it is lower than roughly 50m. As the layer grows, the importance of the Zilitinkevich correction diminishes. Then mechanical turbulence dominates the growth process until the internal boundary layer has reached a height of approximately −1.4L. Further growth is controlled mainly by convective turbulence. Conditions of high wind speed and large values of the potential temperature gradient over water result in a deep zone where the growth of the internal boundary layer is controlled by mechanical turbulence. With near-zero potential temperature gradient over water, the zone becomes shallow and may vanish.

Low q-moment multifractal analysis of Gold price, Dow Jones Industrial Average and BGL-USD exchange rate

Abstract: An estimate of the low q-moment values of the assumed multifractal spectrum of Gold price, Dow Jones Industrial Average (DJIA) and Bulgarian Lev - USA Dollar (BGL-USD) exchange rate over a 6 1/2 year time span has been made. The findings can be compared to the analysis made on 23 foreign currency exchange rates by Vandewalle and Ausloos but there is a clear indication of some differences. Comparison to fractional Brownian motion is made. The analysis shows that these three financial data are not likely fractal but rather multifractal indeed.

Resolutions of monomial ideals and cohomology over exterior algebras

Abstract: This paper studies the homology of finite modules over the exterior algebra E of a vector space V . To such a module M we associate an algebraic set VE(M) ⊆ V , consisting of those v ∈ V that have a non-minimal annihilator in M . A cohomological description of its defining ideal leads, among other things, to complementary expressions for its dimension, linked by a ‘depth formula’. Explicit results are obtained for M = E/J , when J is generated by products of elements of a basis e1, . . . , en of V . A (infinite) minimal free resolution of E/J is constructed from a (finite) minimal resolution of S/I, where I is the squarefree monomial ideal generated by ‘the same’ products of the variables in the polynomial ring S = K[x1, . . . , xn]. It is proved that VE(E/J) is the union of the coordinate subspaces of V , spanned by subsets of { e1, . . . , en } determined by the Betti numbers of S/I over S.