44,087 research outputs found
Affine Pieri rule for periodic Macdonald spherical functions and fusion rings
No full textLet gˆ be an untwisted affine Lie algebra or the twisted counterpart thereof (which excludes the affine Lie algebras of type BCˆn=A2n(2)). We present an affine Pieri rule for a basis of periodic Macdonald spherical functions associated with gˆ. In type Aˆn−1=An−1(1) the formula in question reproduces an affine Pieri rule for cylindric Hall-Littlewood polynomials due to Korff, which at t=0 specializes in turn to a well-known Pieri formula in the fusion ring of genus zero slˆ(n)c-Wess-Zumino-Witten conformal field theories.Applied Probabilit
A Pieri-Type Formula for H*T(SLn(C)/B)
No full textAbstractThe singular cohomology of the Grassmann variety of k-planes in Cn has a basis {sν} indexed by partitions. The classical Pieri formula is an explicit rule for determining the coefficients in the expansion of the cup products1m∪sλ=∑c1m,λμsμ,where 1m is a column of length m and s1m is the mth Chern class of the tautological bundle. Lascoux and Schutzenberger [C. R. Acad. Sci. Paris294 (1982), 447–450] formulated a generalization of Pieri's formula to the cohomology of the flag variety SLn(C)/B and briefly indicated an algebraic proof. (Manivel [Cours Spécialisés 3 (1998)] provides details of this proof.) A geometric proof was given by Sottile [Ann. Inst. Fourier (Grenoble) 46 (1996), 89–110]. In this paper we state and prove a generalization of this Pieri-type formula for the T-equivariant cohomology of the flag variety. We use the algebraic description of the T-equivariant cohomology of the flag variety due to Kostant and Kumar [Adv. Math.62 (1986), 187–237] and Arabia [Bull. Soc. Math. France117 (1989), 129–165], and our new formula exposes an equality of certain structure Constants in this algebra. Our proof is an induction based on the original idea in Lascoux and Schützenberger
Pairing effects in the normal phase of a two-dimensional Fermi gas
No full textIn recent experiments [1, 2], a pairing gap was detected in a two-dimensional (2D)
Fermi gas with attractive interaction at temperatures where superfluidity does not occur.
A relevant question is whether this gap is a pseudogap phenomenon or is due to a molecular
state, which is always present in 2D. In this talk I will discuss how the boundary between
the pseudogap and molecular regimes can be set, and compare the theoretical results
obtained by using a t-matrix approach [3] with the above experimental data for a 2D
Fermi gas. I will also show that pseudogap phenomena occurring in 2D and 3D can be
related through a variable spanning the BCS-BEC crossover in a universal way.
[1] M. Feld, B. Fr ̈ohlich, E. Vogt, M. Koschorreck, and M. K ̈ohl, Nature 480, 75 (2011).
[2] P. A. Murthy, M. Neidig, R. Klemt, L. Bayha, I. Boettcher, T. Enss, M. Holten, G. Z ̈urn,
P. M. Preiss, and S. Jochim, arXiv:1705.10577 (2017).
[3] F. Marsiglio, P. Pieri, A. Perali, F. Palestini, and G. C. Strinati, Phys. Rev. B 91, 054509
(2015
The c-myc gene regulates the polyamine pathway in DMSO-induced apoptosis.
No full textIt is accepted that apoptosis is a gene-controlled process of cellular self-destruction. It occurs during physiological regulation and in pathological situations in the life of a cell. In the immune system, several different intracellular and extracellular factors have been associated with the induction of apoptosis, and the final responses depend on the cell system and the acquired signals. In lymphoid cells, dexamethasone-induced apoptosis is associated with c-myc downregulation in cells that remain in G0-G1 until the point of death. Ornithine decarboxylase (ODC), a key enzyme involved in polyamine biosynthesis, is regulated by c-myc, which is a transcriptional activator implicated not only in the control of cell proliferation and differentiation but also in programmed cell death. As dimethylsulphoxide (DMSO) induces apoptosis in the RPMI-8402 human pre-T cell line, the present study analysed the involvement of the c-myc proto-oncogene and polyamine pathway as mediators of apoptosis. Cell growth, programmed cell death, c-myc expression, ODC activity and intracellular polyamine content were detected after DMSO and difluoromethylornithine (DFMO) treatment. DMSO-treated cells exhibit a decrease in ODC activity and polyamine levels associated with cell growth arrest and programmed cell death induction. The expression of c-myc proto-oncogene, as its mRNA or protein, is specifically down-regulated. DFMO, a well defined polyamine biosynthesis inhibitor, completely blocks ODC activity, resulting in growth inhibition but not apoptosis. Moreover, in these samples no evidence of changes of c-myc expression were found. The results obtained suggest that, in RPMI-8402 cells, DMSO provokes a c-myc-dependent decrease of ODC activity followed by a depletion of intracellular polyamine levels, associated with programmed cell death and cell growth arrest
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
On Delisting of Corporations: a Three-Dimensional Classification Framework for Voluntary Delistings
No full textThe study of the effects of delisting on the dynamics of value and governance of delisted companies represents a very promising research opportunity for international scholars. This paper addresses a preliminary question, i.e. how, in the face of a complex phenomenon with a significant number of highly differentiating characteristics, it is possible to avoid the risk that a conjunct observation of operations that differ too much one from the other might raise significant obstacles to the application of the main models of qualitative and/or quantitative analysis. We define a classification framework that deepens the fundamental distinction between voluntary and involuntary delistings. A particular focus is on voluntary delistings, which we differentiate in the light of three main characterising features: i) the subjects who pursue delisting, ii) the underlying strategic context and iii) the operating conditions of the delisted company. Our three-dimensional classification framework defines eight homogeneous areas of observation (pre-sale delistings, hidden potential delistings, control strengthening delistings and takeover delistings, either in balanced operating conditions or in presence of crisis/operating distress) and may be a useful starting point for future studies on the effects of delisting on the dynamics of value and governance of the delisted company
Affine Pieri rule for periodic Macdonald spherical functions and fusion rings
No full textLet gˆ be an untwisted affine Lie algebra or the twisted counterpart thereof (which excludes the affine Lie algebras of type BCˆn=A2n(2)). We present an affine Pieri rule for a basis of periodic Macdonald spherical functions associated with gˆ. In type Aˆn−1=An−1(1) the formula in question reproduces an affine Pieri rule for cylindric Hall-Littlewood polynomials due to Korff, which at t=0 specializes in turn to a well-known Pieri formula in the fusion ring of genus zero slˆ(n)c-Wess-Zumino-Witten conformal field theories.Fil: van Diejen, Jan Felipe. Universidad de Talca; ChileFil: Emsiz, Erdal. Delft University of Technology; Países BajosFil: Zurrián, Ignacio Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentin
Letter from Carl T. Hayden to C. H. Gensler, Havasupai Reservation
No full textLetter from Carl T. Hayden to C. H. Gensler, Havasupai Indian Reservation, regarding Hualapai and Cataract Canyons geography
Discussion
No full textBeyrouth et sa banlieue sud Photo C. Pieri 2011 Khalil Gemayel (Union des déplacés de la montagne) : À partir des travaux faits par l’Union des déplacés de la montagne, il serait intéressant d’approcher l’histoire de la banlieue, de l’extension des villes en lien avec la question des déplacés de la guerre civile. Comment ce déplacement a-t-il eu lieu ? Y a-t-il eu relogement ou expulsion de ces déplacés ? Mona Fawaz : Il existe sur ce point des travaux très intéressants, ceux de Assir Saoual..
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