220 research outputs found
Wetting films on chemically heterogeneous substrates
Based on a microscopic density functional theory we investigate the
morphology of thin liquidlike wetting films adsorbed on substrates endowed with
well-defined chemical heterogeneities. As paradigmatic cases we focus on a
single chemical step and on a single stripe. In view of applications in
microfluidics the accuracy of guiding liquids by chemical microchannels is
discussed. Finally we give a general prescription of how to investigate
theoretically the wetting properties of substrates with arbitrary chemical
structures.Comment: 56 pages, RevTeX, 20 Figure
Climate-driven range extension of Amphistegina (protista, foraminiferida) : models of current and predicted future ranges
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 8 (2013): e54443, doi:10.1371/journal.pone.0054443.Species-range expansions are a predicted and realized consequence of global climate change. Climate warming and the poleward widening of the tropical belt have induced range shifts in a variety of marine and terrestrial species. Range expansions may have broad implications on native biota and ecosystem functioning as shifting species may perturb recipient communities. Larger symbiont-bearing foraminifera constitute ubiquitous and prominent components of shallow water ecosystems, and range shifts of these important protists are likely to trigger changes in ecosystem functioning. We have used historical and newly acquired occurrence records to compute current range shifts of Amphistegina spp., a larger symbiont-bearing foraminifera, along the eastern coastline of Africa and compare them to analogous range shifts currently observed in the Mediterranean Sea. The study provides new evidence that amphisteginid foraminifera are rapidly progressing southwestward, closely approaching Port Edward (South Africa) at 31°S. To project future species distributions, we applied a species distribution model (SDM) based on ecological niche constraints of current distribution ranges. Our model indicates that further warming is likely to cause a continued range extension, and predicts dispersal along nearly the entire southeastern coast of Africa. The average rates of amphisteginid range shift were computed between 8 and 2.7 km yearâ1, and are projected to lead to a total southward range expansion of 267 km, or 2.4° latitude, in the year 2100. Our results corroborate findings from the fossil record that some larger symbiont-bearing foraminifera cope well with rising water temperatures and are beneficiaries of global climate change.This work was supported by grants from the German Science Foundation (DFG; www.dfg.de) to ML and SL (LA 884/10-1, LA 884/5-1)
Non-factorizable contributions in hadronic weak decays of charm mesons
Two body decays of charm mesons are studied by describing their amplitude in
terms of a sum of factorizable and non-factorizable ones. The former is
estimated by using a naive factorization while the latter is calculated by
using a hard pseudo-scalar-meson approximation. The hard pseudo-scalar-meson
amplitude is given by a sum of the so-called equal-time commutator term and
surface term which contains all possible pole contributions of various mesons,
not only the ordinary but also four-quark ,
hybrid and glue-balls.
Naively factorized amplitudes for the spectator decays which lead to too big
rates can interfere destructively with exotic meson pole amplitudes and the
total amplitudes can reproduce their observed rates. The non-factorizable
contributions can supply sufficiently large contributions to the color
suppressed decays which are strongly suppressed in the naive factorization. A
possible solution to the long standing puzzle that the ratio of decay rates for
to is around 2.5 is given by different
contributions of exotic meson poles.Comment: 22 pages, RevTe
The nucleus reuniens: a key node in the neurocircuitry of stress and depression
Uncorrected proofThe hippocampus and prefrontal cortex (PFC) are connected in a reciprocal manner: whereas the hippocampus projects directly to the PFC, a polysynaptic pathway that passes through the nucleus reuniens (RE) of the thalamus relays inputs from the PFC to the hippocampus. The present study demonstrates that lesioning and/or inactivation of the RE reduces coherence in the PFC-hippocampal pathway, provokes an antidepressant-like behavioral response in the forced swim test and prevents, but does not ameliorate, anhedonia in the chronic mild stress (CMS) model of depression. Additionally, RE lesioning before CMS abrogates the well-known neuromorphological and endocrine correlates of CMS. In summary, this work highlights the importance of the reciprocal connectivity between the hippocampus and PFC in the establishment of stress-induced brain pathology and suggests a role for the RE in promoting resilience to depressive illness.Greece for providing sertraline. This work was supported by an âEducation and Lifelong Learning, Supporting Postdoctoral Researchersâ, co-financed by the European Social Fund (ESF) and the General Secretariat for Research and Technology, Greece, the Life and Health Sciences Research Institute (ICVS), ON.2âO NOVO NORTEâNorth Portugal Regional Operational Program 2007/2013 of the National Strategic Reference Framework (NSRF) 2007/2013 through the European Regional Development Fund (ERDF), the Portuguese Foundation for Science and Technology (FCT; grant no. NMC-113934) and an InEurope program funded by International Brain Research Organizationinfo:eu-repo/semantics/publishedVersio
Say on Pay: A wolf in sheepâs clothing?
This paper debates whether Say on Pay can fix executive pay. We argue that Say on Pay benefits executive pay when shareholdersâ voice offsets CEO power and mitigates directorsâ information deficiencies. We admonish however that Say on Pay may raise novel problems. The pay resulting from Say on Pay can harm stakeholders whose interests differ from those of shareholders influential in pay- setting. Moreover, boards may resist shareholdersâ intervention in pay-setting and, accordingly, manage compensation disclosures to ensure a passing shareholder vote. Consequently, Say on Pay may not only fail to remedy suboptimal pay but also legitimize it
Interlocking directorates as a thrust substitute: The case of the Italian non-life insurance industry
This paper investigates the market structure of the insurance business by
analyzing the (interlock) linkages among companies created by their directors. We
focus on the non-life business since this is a sector relatively closed with respect to
the competition with other financial activities; an absence of industry competition
cannot thus be compensated by other agents. We apply the graph theory to describe
the network and the principal component analysis to summarize information and
verify the correlation between direct interlocking and companiesâ market shares
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