485 research outputs found
Biomechanics of predator–prey arms race in lion, zebra, cheetah and impala
The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator–prey pairs, lion–zebra and cheetah–impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator–prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate
Ground states of a one-dimensional lattice-gas model with an infinite range nonconvex interaction. A numerical study
We consider a lattice-gas model with an infinite range pairwise noncovex
interaction. It might be relevant, for example, for adsorption of alkaline
elements on W(112) and Mo(112). We study a competition between the effective
dipole-dipole and indirect interactions. The resulting ground state phase
diagrams are analysed (numerically) in detail. We have found that for some
model parameters the phase diagrams contain a region dominated by several
phases only with periods up to nine lattice constants. The remaining phase
diagrams reveal a complex structure of usually long periodic phases. We also
discuss a possible role of surace states in phase transitions.Comment: 16 pages, 5 Postscript figures; Physical Review B15 (15 August 1996),
in pres
A collagen IV-derived peptide disrupts α5β1 integrin and potentiates Ang2/Tie2 signaling
The angiopoietin (Ang)/Tie2 signaling pathway is essential for maintaining vascular homeostasis, and its dysregulation is associated with several diseases. Interactions between Tie2 and α5 β1 integrin have emerged as part of this control; however, the mechanism is incompletely understood. AXT107, a collagen IV–derived peptide, has strong antipermeability activity and has enabled the elucidation of this previously undetermined mechanism. Previously, AXT107 was shown to inhibit VEGFR2 and other growth factor signaling via receptor tyrosine kinase association with specific integrins. AXT107 disrupts α5 β1 and stimulates the relocation of Tie2 and α5 to cell junctions. In the presence of Ang2 and AXT107, junctional Tie2 is activated, downstream survival signals are upregulated, F-actin is rearranged to strengthen junctions, and, as a result, endothelial junctional permeability is reduced. These data suggest that α5 β1 sequesters Tie2 in nonjunctional locations in endothelial cell membranes and that AXT107-induced disruption of α5 β1 promotes clustering of Tie2 at junctions and converts Ang2 into a strong agonist, similar to responses observed when Ang1 levels greatly exceed those of Ang2. The potentiation of Tie2 activation by Ang2 even extended to mouse models in which AXT107 induced Tie2 phosphorylation in a model of hypoxia and inhibited vascular leakage in an Ang2-overexpression transgenic model and an LPS-induced inflammation model. Because Ang2 levels are very high in ischemic diseases, such as diabetic macular edema, neovascular age-related macular degeneration, uveitis, and cancer, targeting α5 β1 with AXT107 provides a potentially more effective approach to treat these diseases.Fil: Mirando, Adam C.. University Johns Hopkins; Estados UnidosFil: Shen, Jikui. University Johns Hopkins; Estados UnidosFil: Silva, Raquel Lima E.. University Johns Hopkins; Estados UnidosFil: Chu, Zenny. University Johns Hopkins; Estados UnidosFil: Sass, Nicholas C.. University Johns Hopkins; Estados UnidosFil: Lorenc, Valeria Erika. University Johns Hopkins; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Green, Jordan J.. University Johns Hopkins; Estados Unidos. AsclepiX Therapeutics; Estados UnidosFil: Campochiaro, Peter A.. University Johns Hopkins; Estados UnidosFil: Popel, Aleksander S.. University Johns Hopkins; Estados UnidosFil: Pandey, Niranjan B.. University Johns Hopkins; Estados Unidos. AsclepiX Therapeutics; Estados Unido
Uncovered diversity of a predominantly andean butterfly clade in the brazilian atlantic forest : a revision of the genus praepedaliodes forster (Lepidoptera: Nymphalidae, Satyrinae, Satyrini)
The genus Praepedaliodes Forster, 1964, the only representative of the mega-diverse mostly Andean Pedaliodes complex lineage in the Brazilian Atlantic Forest, is revised. Prior to this study, four species were known, P. phanias (Hewitson, 1862), P. granulata (Butler, 1868), P. amussis (Thieme, 1905) and P. exul (Thieme, 1905). Here, a further six are described, all from SE Brazil, expanding to 10 the number of species in this genus. Lectotypes are designated for P. phanias, P. granulata and P. amussis. The genus is most diverse in the Serra da Mantiqueira (São Paulo, Rio de Janeiro, Minas Gerais) and in the Serra Geral (Paraná, Santa Catarina) with seven species occurring in both ranges. Praepedaliodes phanias is the most widespread species and the only one found in the western part of the Atlantic Forest; only this species and P. duartei Dias, Dolibaina & Pyrcz n. sp. occurring to near sea level. Other species, P. zaccae Dolibaina, Dias & Pyrcz n. sp., P. francinii Freitas & Pyrcz n. sp., P. sequeirae Pyrcz, Dias & Dolbaina n. sp., P. landryi Pyrcz & Freitas n. sp. and P. pawlaki Pyrcz & Boyer n. sp. are strictly montane and the highest species richness is reached at 1400–1800 m. One species, P. sequeirae n. sp., is a narrow endemic found only at timberline in the Agulhas Negras massif above 2300 m. Immature stages are described for two species, P. phanias and P. landryi n. sp. Molecular data (barcode region of cytochrome oxidase, subunit I) and adult morphology, including male and female genitalia, support the genus as monophyletic, belonging to a predominantly Andean clade of the Pedaliodes Butler, 1867 complex. Morphological evidences, in particular female genitalia comparative analysis, indicate the genera Physcopedaliodes Forster, 1964 and Panyapedaliodes Forster, 1964 as possibly the closest relatives to Praepedaliodes. Molecular data are inconclusive in this respect472211255CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP302585/2011-7, 303834/2015-3; 563332/2010-7; 41143/2009-6; 150542/2013-5; 308247/2013-2; 304639/2014-1Não tem2016/15873-8; 2011/50225-3; 2013/50297-0We would like to express our gratitude the following persons who contributed at different stages in the elaboration of this paper: Alfred Moser (Porto Alegre), Ronaldo Francini (UNISANTOS) and André Tacioli, Junia Y. O. Carreira, Jessie P. Santos and Ana K. Silva (Unicamp) for logistical help in the field, comparison material and hosting Tamara M. C. Aguiar spread most of the adult DNA vouchers and the old material collected by K. S. Brown Jr. The following people helped by sending material and information: Roberto R. Greve (Foz do Iguaçu), Richard Raby (Serra da Bocaina), Augusto H. B. Rosa (Mantiqueira region), Geanne C. N. Pereira (Serra do Cipó) and Keith S. Brown Jr. (several places in SE Brazil). The authors also thank the ICMBio for the permits (#10438-1, #26712-4 and #10802-9), the CNPq by aproving our Scientific Expedition (portaria N° 240, de 11 de março de 2014) and all managers of the Conservation Unities visited during the development of the present study, in special Waldomiro P. Lopes (Parque Nacional do Caparaó), Léo Nascimento (Parque Nacional do Itatiaia), Mara P. Pais (Parque Nacional da Serra da Bocaina), Ingo Grantsau (Paranapiacaba) and Cecilia Cronemberger (Parque Nacional da Serra dos Órgãos). EPB thanks Fundação de Amparo à Pesquisa no Estado de São Paulo (FAPESP) for a Post-doc fellowship (2016/15873-8). AVLF thanks the CNPq (fellowships 302585/2011-7, 303834/2015-3 and SISBIOTABrasil/CNPq - 563332/2010-7), the National Science Foundation (DEB-1256742), the “Rede Nacional de Identificação Molecular da Biodiversidade - BR-BoL” (MCT/CNPq/FNDCT 50/2010) and the BIOTA-FAPESP Program (2011/50225-3 and 2013/50297-0). Kim Garwood kindly provided the photographs of two species of Praepedaliodes in their natural habitat. Keith Willmott read the manuscript and added several valuable suggestions. Carlos Prieto provided the photograph of the syntype of Praepedaliodes amussis. TWP field work in SE Brazil was supported by MZ/IZ/UJ internal grants. FMSD, DRD, OHHM and MMC thank Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Edital 15/2014 CAPES/EMBRAPA) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, 141143/2009-6, 150542/2013-5, 308247/2013-2, 304639/2014-1), for the fellowships granted to the author
Observation of Radiative Leptonic Decay of the Tau Lepton
Using 4.68 fb^{-1} of e^+e^- annihilation data collected with the CLEO II
detector at the Cornell Electron Storage Ring (CESR) we have studied tau
radiative decays tau -> mu nu nu gamma and tau -> e nu nu gamma. For a 10 MeV
minimum photon energy in the tau rest frame, the branching fraction of
radiative tau decay to a muon or electron is measured to be
(3.61+-0.16+-0.35)*10^{-3} or (1.75+-0.06+-0.17)*10^{-2}, respectively. The
branching fractions are in agreement with the Standard Model theoretical
predictions.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Hadronic Structure in the Decay
We report on a study of the invariant mass spectrum of the hadronic system in
the decay tau- -> pi- pi0 nu_tau. This study was performed with data obtained
with the CLEO II detector operating at the CESR e+ e- collider. We present fits
to phenomenological models in which resonance parameters associated with the
rho(770) and rho(1450) mesons are determined. The pi- pi0 spectral function
inferred from the invariant mass spectrum is compared with data on e+ e- -> pi+
pi- as a test of the Conserved Vector Current theorem. We also discuss the
implications of our data with regard to estimates of the hadronic contribution
to the muon anomalous magnetic moment.Comment: 39 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Observation of Two Narrow States Decaying into and
We report the first observation of two narrow charmed strange baryons
decaying to and , respectively, using data from
the CLEO II detector at CESR. We interpret the observed signals as the
and , the symmetric partners
of the well-established antisymmetric and .
The mass differences and
are measured to be and
, respectively.Comment: 11 pages, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Search for Baryon and Lepton Number Violating Decays of the Lepton
We have searched for five decay modes of the tau lepton that simultaneously
violate lepton and baryon number: tau -> anti-proton gamma, tau -> anti-proton
pi0, tau -> anti-proton eta, tau -> anti-proton 2pi0, and tau -> anti-proton
pi0eta. The data used in the search were collected with the CLEO II detector at
the Cornell Electron Storage Ring (CESR). The integrated luminosity of the data
sample is 4.7 fb^{-1}, corresponding to the production of 4.3 x 10^6 tau+tau-
events. No evidence is found for any of the decays, resulting in much improved
upper limits on the branching fractions for the two-body decays and first upper
limits for the three-body decays.Comment: 8 pages, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
- …