oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2016 ( 1 )

2014 ( 9 )

2013 ( 19 )

2012 ( 20 )

Custom range...

Search Results: 1 - 10 of 134 matches for " Levitt "
All listed articles are free for downloading (OA Articles)
Page 1 /134
Display every page Item
Patricia Goldman-Rakic
Pat Levitt
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0000038
Abstract:
A Transnational Gaze
Levitt, Peggy;
Migraciones internacionales , 2011,
Abstract: in the decade since this journal was founded, major demographic shifts caused shifts in migration studies. against this backdrop, the questions migration scholars ask and the analytical and methodological tools we use to answer them have changed dramatically. in this essay, i take an idiosyncratic look at these developments and propose directions for the future. i focus on the analytical rewards of using a transnational perspective to study migration, on the importance of considering space and scale in our work, and on bringing culture more centrally back into our conversations. i highlight opportunities at interdisciplinary intersections that, can move our field forward in new productive directions if we take advantage of them.
UK Biobank: a model for public engagement?
Mairi Levitt
Genomics, Society and Policy , 2005,
Abstract:
A Transnational Gaze
Peggy Levitt
Migraciones internacionales , 2011,
Abstract: En los 10 a os que tiene de haberse fundado esta revista, importantes cambios demográficos han dado lugar a transformaciones en los estudios sobre migración. Desde esta perspectiva, las preguntas que se hacen los estudiosos de la migración y las herramientas de análisis y metodología que utilizan para responderlas se han modificado drásticamente. En este ensayo se echa un vistazo idiosincrásico a estos cambios y se propone un rumbo a seguir en el futuro. El estudio se concentra en las ventajas analíticas de utilizar una perspectiva transnacional para el estudio de la migración, en la importancia de tomar en cuenta el espacio y la magnitud de nuestro trabajo, y en situar de nuevo la cultura en el centro de nuestros debates. Así mismo se destacan las oportunidades que las intersecciones interdisciplinarias nos brindan para que nuestro campo avance en una nueva y más productiva dirección.
Patricia Goldman-Rakic
Pat Levitt
PLOS Biology , 2003, DOI: 10.1371/journal.pbio.0000038
Abstract:
On the automorphism group of generalized Baumslag-Solitar groups
Gilbert Levitt
Mathematics , 2005, DOI: 10.2140/gt.2007.11.473
Abstract: A generalized Baumslag-Solitar group (GBS group) is a finitely generated group $G$ which acts on a tree with all edge and vertex stabilizers infinite cyclic. We show that Out(G) either contains non-abelian free groups or is virtually nilpotent of class at most 2. It has torsion only at finitely many primes. One may decide algorithmically whether Out(G) is virtually nilpotent or not. If it is, one may decide whether it is virtually abelian, or finitely generated. The isomorphism problem is solvable among GBS groups with Out(G) virtually nilpotent. If $G$ is unimodular (virtually $F_n \times Z$), then Out(G) is commensurable with a semi-direct product $Z^k \rtimes Out(H)$ with $H$ virtually free.
Counting growth types of automorphisms of free groups
Gilbert Levitt
Mathematics , 2008,
Abstract: Given an automorphism of a free group $F_n$, we consider the following invariants: $e$ is the number of exponential strata (an upper bound for the number of different exponential growth rates of conjugacy classes); $d$ is the maximal degree of polynomial growth of conjugacy classes; $R$ is the rank of the fixed subgroup. We determine precisely which triples $(e,d,R)$ may be realized by an automorphism of $F_n$. In particular, the inequality $e\le (3n-2)/4}$ (due to Levitt-Lustig) always holds. In an appendix, we show that any conjugacy class grows like a polynomial times an exponential under iteration of the automorphism.
Generalized Baumslag-Solitar groups: rank and finite index subgroups
Gilbert Levitt
Mathematics , 2013,
Abstract: A generalized Baumslag-Solitar (GBS) group is a finitely generated group acting on a tree with infinite cyclic edge and vertex stabilizers. We show how to determine effectively the rank (minimal cardinality of a generating set) of a GBS group; as a consequence, one can compute the rank of the mapping torus of a finite order outer automorphism of a free group $F_n$. We also show that the rank of a finite index subgroup of a GBS group G cannot be smaller than the rank of G. We determine which GBS groups are large (some finite index subgroup maps onto $F_2$), and we solve the commensurability problem (deciding whether two groups have isomorphic finite index subgroups) in a particular family of GBS groups.
Unsolvability of the isomorphism problem for [free abelian]-by-free groups
Gilbert Levitt
Mathematics , 2008,
Abstract: The isomorphism problem for [free abelian]-by-free groups is unsolvable.
Automorphisms of hyperbolic groups and graphs of groups
Gilbert Levitt
Mathematics , 2002,
Abstract: Using the canonical JSJ splitting, we describe the outer automorphism group $\Out(G)$ of a one-ended word hyperbolic group $G$. In particular, we discuss to what extent $\Out(G)$ is virtually a direct product of mapping class groups and a free abelian group, and we determine for which groups $\Out(G)$ is infinite. We also show that there are only finitely many conjugacy classes of torsion elements in $\Out(G)$, for $G$ any torsion-free hyperbolic group. More generally, let $\Gamma $ be a finite graph of groups decomposition of an arbitrary group $G$ such that edge groups $G_e$ are rigid (i.e\. $\Out(G_e)$ is finite). We describe the group of automorphisms of $G$ preserving $\Gamma $, by comparing it to direct products of suitably defined mapping class groups of vertex groups.
Page 1 /134
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.