On Legendrian Embbeddings into Open Book Decompositions

We study Legendrian embeddings of a compact Legendrian submanifold $L$ sitting in a closed contact manifold $(M,\xi)$ whose contact structure is supported by a (contact) open book $\mathcal{OB}$ on $M$. We prove that if $\mathcal{OB}$ has Weinstein pages, then there exist a contact structure $\xi'$ on $M$, isotopic to $\xi$ and supported by $\mathcal{OB}$, and a contactomorphism $f:(M,\xi) \to (M,\xi')$ such that the image $f(L)$ of any such submanifold can be Legendrian isotoped so that it becomes disjoint from the closure of a page of $\mathcal{OB}$.Comment: 14 pages, 4 figures. Major corrections made. arXiv admin note: substantial text overlap with arXiv:1003.220

Ethnic concentration and language fluency of immigrants : quasi-experimental evidence from the guest-worker placement in Germany (Ethnische Konzentration und Sprachkompetenz von Einwanderern : quasi-experimentelle Befunde aus der Gastarbeiteranwerbung in Deutschland)

"The paper analyses the impact of regional own-ethnic concentration on the language proficiency of immigrants. It solves the endogeneity of immigrants' location choices by exploiting the fact that guest-workers in Germany after WWII were initially placed by firms and labor agencies. We find a robust negative effect of ethnic concentration on immigrants' language ability. Simulation results of a simultaneous location and learning choice model confirm the presence of the effect and show how immigrants with high learning cost select into ethnic enclaves. Under the counterfactual scenario of a regionally equal distribution of immigrants the share of German-speakers increases only modestly." (Author's abstract, IAB-Doku) ((en))Einwanderer, Beschäftigungspolitik, Arbeitskräftemangel, Wohnort, Einwanderungsland, Sprachkenntnisse, deutsche Sprache, ethnische Gruppe, Ballungsraum

Ethnic Concentration and Language Fluency of Immigrants in Germany

Studies that investigate the effect of the regional ethnic composition on immigrant outcomes have been complicated by the self-selection of ethnic minorities into specific neighbourhoods. We analyse the impact of own-ethnic concentration on the language proficiency of immigrants by exploiting the fact that the initial placement of guest-workers after WWII was determined by labour demanding firms and the federal labour administration and hence exogenous to immigrant workers. Combining several data sets, we find a small but robust and significant negative effect of ethnic concentration on immigrants' language ability. Simulation results of a choice model in which location and learning decisions are taken simultaneously confirm the presence of the effect. Immigrants with high learning costs are inclined to move to ethnic enclaves, so that the share of German-speakers would increase only modestly even under the counterfactual scenario of a regionally equal distribution of immigrants across Germany.enclave, ethnic concentration, language proficiency, immigrants, Instrumental variable, random utility model