22,225 research outputs found
On the scalar curvature of constant mean curvature hypersurfaces in space forms
In this paper we study the behavior of the scalar curvature of a complete
hypersurface immersed with constant mean curvature into a Riemannian space form
of constant curvature, deriving a sharp estimate for the infimum of . Our
results will be an application of a weak Omori-Yau maximum principle due to
Pigola, Rigoli and Setti \cite{PRS}.Comment: Final version (August 2009). To appear in Journal of Mathematical
Analysis and Applications. Dedicated to Professor Marcos Dajczer on the
occasion of his 60th birthda
A new contribution to the nuclear modification factor of non-photonic electrons in Au+Au collisions at sqrt(s) = 200 GeV
We investigate the effect of the so-called anomalous baryon/meson enhancement
to the nuclear modification factor of non-photonic electrons in Au+Au
collisions at sqrt(s) = 200 GeV. It is demonstrated that an enhancement of the
charm baryon/meson ratio, as it is observed for non-strange and strange
hadrons, can be responsible for part of the amplitude of the nuclear
modification factor of non-photonic electrons. About half of the measured
suppression of non-photonic electrons in the 2-4 pt range can be explained by a
charm baryon/meson enhancement of 5. This contribution to the non-photonic
electron nuclear modification factor has nothing to do with heavy quark energy
loss.Comment: 14 pages, 3 figure
From car to bike. Marketing and dialogue as a driver of change
The Paris Climate Agreement has sent a key message to the international community regarding the need to increase efforts to move towards a low-carbon economy and help slow climate change, while underpinning global long-term economic growth and sustainable development. COP 21 recognizes the social, economic and environmental value of voluntary mitigation actions and their co-benefits for adaptation, health and sustainable development. In this framework, the PTP Cycle project, running from 2013 to 2016 and funded by the European Commission through the Intelligent Energy Europe program, introduces a non-market approach through voluntary participation in the adoption of sustainable transport modes such as cycling, based on marketing to potential customers through Personalized Travel Plans. The medium-sized city of Burgos (Spain) and the cities of Ljubljana, Riga, Antwerp and London
(boroughs of Haringey and Greenwich) developed a new policy instrument (Personalized Travel Plans) in order to increase bike patronage. Beyond potential savings of CO2, the results show that PTP as a form of Active Mobility Consultancy is a suitable instrument to influence modal shift to public transport, walking and cycling, and to address the challenges of climate change, while fostering sustainable transportation by changing mobility behaviour. These results, matching with the state-of-the-art of studies and pilot applications in other countries, allows deriving differentiated results for medium-size and large urban areas
Dynamical generation of wormholes with charged fluids in quadratic Palatini gravity
The dynamical generation of wormholes within an extension of General
Relativity (GR) containing (Planck's scale-suppressed) Ricci-squared terms is
considered. The theory is formulated assuming the metric and connection to be
independent (Palatini formalism) and is probed using a charged null fluid as a
matter source. This has the following effect: starting from Minkowski space,
when the flux is active the metric becomes a charged Vaidya-type one, and once
the flux is switched off the metric settles down into a static configuration
such that far from the Planck scale the geometry is virtually indistinguishable
from that of the standard Reissner-Nordstr\"om solution of GR. However, the
innermost region undergoes significant changes, as the GR singularity is
generically replaced by a wormhole structure. Such a structure becomes
completely regular for a certain charge-to-mass ratio. Moreover, the nontrivial
topology of the wormhole allows to define a charge in terms of lines of force
trapped in the topology such that the density of lines flowing across the
wormhole throat becomes a universal constant. To the light of our results we
comment on the physical significance of curvature divergences in this theory
and the topology change issue, which support the view that space-time could
have a foam-like microstructure pervaded by wormholes generated by quantum
gravitational effects.Comment: 14 pages, 3 figures, revtex4-1 style. New content added on section
VI. Other minor corrections introduced. Final version to appear in Phys. Rev.
Eigenvalue estimates for submanifolds of warped product spaces
We give lower bounds for the fundamental tone of open sets in minimal
submanifolds immersed into warped product spaces of type ,
where . We also study the essential spectrum of these
minimal submanifolds.Comment: 17 page
L1CAM binds ErbB receptors through Ig-like domains coupling cell adhesion and neuregulin signalling.
During nervous system development different cell-to-cell communication mechanisms operate in parallel guiding migrating neurons and growing axons to generate complex arrays of neural circuits. How such a system works in coordination is not well understood. Cross-regulatory interactions between different signalling pathways and redundancy between them can increase precision and fidelity of guidance systems. Immunoglobulin superfamily proteins of the NCAM and L1 families couple specific substrate recognition and cell adhesion with the activation of receptor tyrosine kinases. Thus it has been shown that L1CAM-mediated cell adhesion promotes the activation of the EGFR (erbB1) from Drosophila to humans. Here we explore the specificity of the molecular interaction between L1CAM and the erbB receptor family. We show that L1CAM binds physically erbB receptors in both heterologous systems and the mammalian developing brain. Different Ig-like domains located in the extracellular part of L1CAM can support this interaction. Interestingly, binding of L1CAM to erbB enhances its response to neuregulins. During development this may synergize with the activation of erbB receptors through L1CAM homophilic interactions, conferring diffusible neuregulins specificity for cells or axons that interact with the substrate through L1CAM
Blurred Lines Between Competition and Parasitism
Accurately describing the ecological relationships between species is more than mere semantics-doing so has profound practical and applied implications, not the least of which is that inaccurate descriptions can lead to fundamentally incorrect predicted outcomes of community composition and functioning. Accurate ecological classifications are particularly important in the context of global change, where species interactions can change rapidly following shifts in species composition. Here, we argue that many common ecological interactions-particularly competition and parasitism-can be easily confused and that we often lack empirical evidence for the full reciprocal interaction among species. To make our case and to propose a theoretical framework for addressing this problem, we use the interactions between lianas and trees, whose outcomes have myriad implications for the ecology and conservation of tropical forests (e.g., Schnitzer et al. 2015)
Microsatellite markers in Spanish lime (Melicoccus bijugatus Jacq., Sapindaceae), a neglected Neotropical fruit crop
Spanish lime (Melicoccus bijugatus Jacq.) is aNeotropical fruit tree cultivated, mainly, in orchards for self-consumption or local sale. The genus Melicoccus includes other nine species with edible fruits, some of these species are at risk of extinction. Like for the vast majority of tropical fruit trees, there is no information on the genetic diversity of Spanish lime and its related species, and this is mostly due to the lack of molecular markers. The objectives of this study were to present the first microsatellite markers developed for Spanish lime, testing its usefulness on a sample of cultivated accessions, as well as its transferability to Huaya India (M. oliviformis). To do this, we performed high-throughput sequencing of microsatellite-enriched libraries of Spanish lime using Roche 454, assembled 9567 DNA contig sequences and identified 10,117 microsatellites. After screening 384 of those microsatellites on four DNA samples, 31 polymorphic markers were used to screen 25 accessions of Spanish lime and five of Huaya India collected in Yucatan, Mexico. Genetic diversity was low in Spanish lime (A = 20.61, HE = 0.38) and similar for both sexes of this species. Neighbor-Joining and PCoA analyses clearly discriminated between the two Melicoccus species studied. Nine of the markers showed unique alleles for Huaya India. The set of microsatellite markers developed has a great potential to generate information in relation to conservation genetics, improvement of elite cultivars and breeding programs for Spanish lime and related species
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