Entropies, volumes, and Einstein metrics

We survey the definitions and some important properties of several asymptotic invariants of smooth manifolds, and discuss some open questions related to them. We prove that the (non-)vanishing of the minimal volume is a differentiable property, which is not invariant under homeomorphisms. We also formulate an obstruction to the existence of Einstein metrics on four-manifolds involving the volume entropy. This generalizes both the Gromov--Hitchin--Thorpe inequality and Sambusetti's obstruction.Comment: This is a substantial revision and expansion of the 2004 preprint, which I prepared in spring of 2010 and which has since been published. The version here is essentially the published one, minus the problems introduced by Springer productio

Intraflagellar transport dynein is autoinhibited by trapping of its mechanical and track-binding elements

Cilia are multi-functional organelles that are constructed using intraflagellar transport (IFT) of cargo to and from their tip. It is widely held that the retrograde IFT motor, dynein-2, must be controlled in order to reach the ciliary tip and then unleashed to power the return journey. However, the mechanism is unknown. Here, we systematically define the mechanochemistry of human dynein-2 motors as monomers, dimers, and multi-motor assemblies with kinesin-II. Combining these data with insights from single-particle electron microscopy, we discover that dynein-2 dimers are intrinsically autoinhibited. Inhibition is mediated by trapping dynein-2’s mechanical “linker” and “stalk” domains within a novel motor-motor interface. We find that linker-mediated inhibition enables efficient transport of dynein-2 by kinesin-II in vitro. These results suggest a conserved mechanism for autoregulation among dimeric dyneins, which is exploited as a switch for dynein-2’s recycling activity during IFT

Does emigration reduce corruption?

© 2017, The Author(s). We study the effects of emigration on bribery experience and attitudes towards corruption in the migrants’ countries of origin. Using data from the Gallup Balkan Monitor survey and instrumental variable analysis, we find that having relatives abroad reduces the likelihood of bribing public officials, renders bribe-taking behavior by public officials less acceptable, and reduces the likelihood of being asked for bribes by public officials. Receiving monetary remittances does not change the beneficial effects regarding bribe paying and attitudes toward corruption; however, remittances counteract the beneficial effect on bribe solicitations by public officials. Overall, our findings support the conjecture that migration contributes to the transfer of norms and practices from destination to source countries

Odd−even Effects in photoemission from terphenyl-substituted alkanethiolate self-assembled monolayers

Self-assembled monolayers (SAMs) formed from 4,4‘-terphenyl-substituted alkanethiols C6H5(C6H4)2(CH2)nSH (TPn, n = 1−6) on polycrystalline (111) gold and silver substrates have been characterized by synchrotron-based high-resolution X-ray photoelectron spectroscopy. The intensities, binding energy positions, and width of most photoemission lines exhibited pronounced odd−even effects, i.e., systematic and periodic variation, depending on either odd or even number of the methylene units in the aliphatic linker of the TPn molecules. The detailed analysis of these effects provides important information on the bonding and arrangement of the chemisorbed sulfur headgroups in the TPn films and balance of the structural forces in alkanethiolate SAMs

Migration, transnationalism and development on the Southeastern flank of Europe

The South-east Europe and Black Sea region presents a fertile terrain for examining recent international migration trends. A wide range of types of migration can be observed in this region: large-scale emigration in many countries, recent mass immigration in the case of Greece, return migration, internal migration, internal and external forced migration, irregular migration, brain drain etc. These migratory phenomena occur within the context of EU migration policies and EU accession for some countries. Yet within this shifting migration landscape of migrant stocks and flows, the fundamental economic geography of different wealth levels and work opportunities is what drives most migration, now as in the past. This paper sets the scene for the special issue in three ways: first, by defining the three key concepts of migration, transnationalism and development; second, by setting the geographical scene, with the aid of relevant statistics on the migration, development and remittance trends in the various countries of the region; and third, by summarizing the highlights of the papers in this issue of the journal, which range in their coverage from Ukraine and Moldova in the north, to Greece and Albania in the south