1,799 research outputs found
<b>Supplemental Material - A data-driven approach to analyse the co-evolution of urban systems through a resilience lens: A Helsinki case study</b>
No full textSupplemental Material for A data-driven approach to analyse the co-evolution of urban systems through a resilience lens: A Helsinki case study by Ylenia Casali, Nazli Yonca Aydin and Tina Comes in Environment and Planning B: Urban Analytics and City Science.</p
REVIEW OF: "Schleimer Saul, The end of the curve complex, Groups Geom. Dyn. 5, No. 1, 169-176 (2011)". [DE059733321]
No full textIf S is a genus g surface with b boundary components, so that 3g − 3 + b 2, then the curve complex C(S)
has a vertex for each isotopy class of essential non-peripheral simple closed curves in S and a k-simplex for
each collection of k + 1 disjoint vertices having disjoint representatives.
By regarding each simplex as a Euclidean simplex of side-length one, C(S) turns out to be Gromov hyperbolic
([Invent. Math. 138, No.1, 103-149 (1999; Zbl 0941.32012)]).
The present paper proves that, if the surface S has exactly one boundary component and genus two or more,
than for each vertex ! 2 C(S) and for any r 2 N, the subcomplex spanned by C0(S) − B(!, r) is connected
(where B(!, r) denotes the ball of radius r about the vertex !).
In order to prove the above result, the author makes use of the fact that the complex of curves has no dead
ends (Prop. 3.1 of this paper) and of the so called Birman short exact sequence (see [Annals of Mathematics
Studies 82, Princeton (1975; Zbl 0305.57013)] and [Acta Math. 146, 231-270 (1981; Zbl 0477.32024)]).
Note that, for the considered surfaces, the above result directly answers a question of Masur’s, and answers
a question of G.Bell and K.Fujiara ([J. Lond. Math. Soc., II. Ser. 77, No. 1, 33-50 (2008; Zbl 1135.57010)])
in the negative. It is also evidence for a positive answer to a question of P.Storm (already verified in an
independent way by Gabai in [Geom. Topol. 13, No. 2, 1017-1041 (2009; Zbl 1165.57015)])
Lower bounds for regular genus and gem-complexity of PL 4-manifolds
No full textWithin crystallization theory, two interesting PL invariants for d-manifolds have been introduced and studied, namely, gem-complexity and regular genus. In the present paper we prove that for any closed connected PL 4-manifold M, its gem-complexity k(M) and its regular genus G(M) satisfy
k(M)≥3χ(M)+10m−6 and G(M)≥2χ(M)+5m−4,
where rk(π1(M))=m. These lower bounds enable to strictly improve previously known estimations for regular genus and gem-complexity of product 4-manifolds. Moreover, the class of semi-simple crystallizations is introduced, so that the represented PL 4-manifolds attain the above lower bounds. The additivity of both gem-complexity and regular genus with respect to connected sum is also proved for such a class of PL 4-manifolds, which comprehends all ones of “standard type”, involved in existing crystallization catalogs, and their connected sums
Diversity and somatic hypermutation of the Ig VHDJH, V kappa J kappa, and V lambda J lambda gene segments in lymphoma B cells : relevance to the origin of the neoplastic B cell clone
No full textBurkitt’s lymphoma (BL) is a malignancy of B cells characterized by chromosomal translocations involving the immunoglobulin (Ig) and c-MYC gene loci. To address the putative role of antigen in the clonal expansion of these neoplastic B cells, we analyzed the VHDJH and VLJL gene segments expressed by the established cell lines derived from six endemic BL and six sporadic BL. Eight BL cell lines used genes of the VH3 family, two of the VH4, and two of the VH1. Eight VL chains were κ (four members of the Vκ3, two of the Vκ1, and two of the Vκ2 subgroups) and four λ (three members of the Vλ1 and one of the Vλ3 subgroup). The VH gene utilization was stochastic (i.e., it reflected the relative representation of the different VH gene family members in the human haploid genome). In contrast, the VL gene utilization was skewed toward the overutilization of the Vκ3 and Vλ1 gene subgroups. When compared with those of the respective germline genes, the sequences of the expressed Ig V(D)J genes displayed nucleotide differences that resulted from somatic hypermutation. In three endemic and three sporadic BL cells, nucleotide changes yielding amino acid substitutions segregated within the complementarity determining region, indicating the application of a positive pressure for replacement mutations and suggesting that these neoplastic lymphocytes underwent a process of clonal selection driven by antigen, perhaps emerging from or transitioning through germinal centers
A universal branching set for 4-dimensional manifolds
No full textIn this work, a universal branching set K for orientable 4-manifolds, such that is proved to exist. This leads to the possibility of representing every closed connected orientable 4-manifold by a suitable transitive set of permutations, in analogy with known results for dimension three (see [Montesinos] and [Costa-delValMelus])
[Recensione di] B. Larosa (ed.), P. Ovidii Nasonis Epistula ex Ponto 3. 1.: testo, traduzione e commento (Berlin; Boston, 2013)
No full textA note on the characterization of handlebodies
No full textThe work is devoted to extend to dimension five the following combinatorial characterization of (orientable and non-orientable) handlebodies, already proved for dimensions three and four by the same author: a compact connected 5-manifold is a handlebody (of genus g) iff G(M^5)= G(\partial M^5} (=g), $G(X) being the regular genus of the manifold X. Moreover, partial results in dimension n induce to conjecture that an analogous characterization also holds for handlebodies of arbitrary dimension
Apollo e Marsia nel proemio del Paradiso
No full text(1) When Dante invokes Apollo saying “Entra nel petto mio, e spira tue | sì come quando Marsïa traesti | de la vagina de le membra sue” (Par. 1.19-21) he most probably understands Ovid’s model (Met. 6.384-5) as meaning that not only Marsyas, but Apollo too played a reed pipe during their contest: “spira tue” (“inspire”) literally means “breathe” and refers to Apollo “breathing into the reed pipe.” Other passages might have suggested to Dante that Apollo too played a reed during his contest with Marsyas; cf. Liv. 38.13, Plin. NH 5.106. A version which explicitly presents Apollo as playing the reed is attested at Agathias, Hist. 4.23.4, and according to Iacomo della Lana, author of the first commentary to the Paradiso (1324-8), both Marsyas and Apollo/Febo would have played a wind instrument in their contest. (2) The reference to Marsyas and Apollo at Par. 1.19-21 is meant to contrast Dante’s humility in his asking God for help with the foolish arrogance of those who presume of singing of sublime matters trusting entirely in their human capacities. This is the correct interpretation of the terzina. There is also another widespread interpretation, which goes back ultimately to an observation of S. T. Coleridge, reported with approval by J. S. Carroll (1907): Marsyas would be a “figura Dantis,” representing the liberation from the body by means of divine inspiration; so e.g. E. Wind, S. Pasquazi, K. Brownlee, P. S. Hawkins, P. Rigo, J. Levenstein, R. Hollander, N. Fosca, among many others. In fact, this is either an overinterpretation, or a mere misunderstanding of Dante’s text
REVIEW OF: "Kawauchi Akio, Splitting a 4-manifold with infinite cyclic fundamental group, revised, J. Knot Theory Ramifications 22, No. 14, Article ID 1350081, 9 p. (2013)". [DE062730205]
No full textIn [Osaka J. Math. 31(3), 489-495 (1994; Zbl 0849.57018 )], the author stated that every closed connected
orientable 4-manifold M with infinite cyclic fundamental group is TOP-split, i.e. it is homeomorphic to
the connected sum (S1 × S3)#M1, M1 being a closed simply connected 4-manifold. However, in [Manuscr.
Math. 93(4), 435-442 (1997; Zbl 0890.57034)], Hambleton and Teichner obtained a counterexample to the
above general statement.
In the paper under review, the author makes a revision and proves that TOP-splittability holds under the
additional hypothesis that a finite covering of M is TOP-split. In particular, the original statement turns
out to be true in the case of indefinite intersection form, as well as for any smooth spin 4-manifold (with
infinite cyclic fundamental group).
The proof of the revised statement makes use of notions developed in [Knots in Hellas 98, Ser. Knots
Everything. 24 (World Scientific Publishing), 208-228 (2000; Zbl 0969.57020)] and [Atti Semin. Mat. Fis.
Univ. Modena 48(2), 405-424 (2000; Zbl 1028.57019)], together with the key result - proved in [Osaka J.
Math. 31(3), 489-495 (1994; Zbl 0849.57018 )] - that every closed connected orientable 4-manifold M with
infinite cyclic fundamental group is homology cobordant to (S1 × S3)#M1.
Consequences about surface-knots in S4 are also considered (see [J. Knot Theory Ramifications 4(2), 213-224
(1995; Zbl 0844.57020)])
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