Search results for "Lasius"
showing 10 items of 22 documents
Group analysis and similarity solutions of the compressible boundary layer equations
1989
In this paper the application of Lie's methods to the equations of the laminar boundary layer is discussed. The momentum and energy equations in Prandtl's form are considered for a steady, viscous, compressible laminar flow with non zero pressure gradient, variable viscosity and thermal conductivity. Group analysis yields similarity solutions for given pressure distributions and particular values of the invariance group parameters (group classification). Crocco's transformation is obtained for the infinite-dimensional group of the Lie's algebra admitted by the equations.
Feromonu un maršruta atmiņas loma kolektīvo lēmumu pieņemšanā melnajai skudrai Lasius niger (Linnaeus, 1758)
2015
Skudru kolonijās feromonu takas ir viens no galvenajiem mehānismiem, kas izmantoti kolektīvo lēmumu pieņemšanā. Tomēr daudziem sociālajiem kukaiņiem ir labi attīstīta atmiņa, kas var darboties arī kā orientieris. Šajā pētījumā tiek atdalīts atmiņas un feromonu efekts uz barotnes izvēli, eksperimenta pirmajā fāzē ļaujot Lasius niger skudru kolonijām iegaumēt un izveidot feromonu taku uz 0,5 M saharozes šķīdumu, bet otrajā fāzē pēc atmiņas vai feromonu taku likvidēšanas piedāvāta izvēle starp to pašu 0,5 M, kā arī 1 M saharozes šķīdumu. Iegūtie rezultāti skaidri parāda, ka, par sākotnējo orientieri izmantojot vienīgi maršruta atmiņu, skudru kolonija nespēj pāriet uz augstākās molaritātes baro…
Community Composition, Antifungal Activity and Chemical Analyses of Ant-Derived Actinobacteria
2020
Actinobacteria associated with insects represent one potentially rich source of novel natural products with antifungal activity. Here, we investigated the phylogenetic diversity and community composition of actinobacteria associated with ants using a combination of culture-dependent and -independent methods. Further, we assessed the antagonistic activity against phytopathogenic fungi and identified the secondary metabolites from isolates with bioactivity. A total of 416 actinobacterial isolates were obtained from three ant species (Camponotus japonicus, Lasius fuliginosus, and Lasius flavus) located in five nests. The largest amount of isolates were observed in the head samples. 16S rRNA ge…
Lasius niger ants discriminate aphids based on their cuticular hydrocarbons
2011
Mutualistic interactions between organisms depend on the ability of each partner to recognize the other. In ant–aphid mutualisms, ants have to recognize whether an aphid colony is worth tending. Many aphid species can live in mutualistic associations with ants (trophobiosis), whereas others are never tended and are frequently preyed upon by ants. Since aphids often produce low amounts of honeydew when not tended by ants, the ants should be able to recognize potential trophobionts based on signals other than honeydew. Conversely, aphids should signal if they are potential trophobionts. We investigated whether ants recognize potential trophobiont aphids based on their behaviour, morphological…
On the Prandtl Boundary Layer Equations in Presence of Corner Singularities
2014
In this paper we prove the well-posedness of the Prandtl boundary layer equations on a periodic strip when the initial and the boundary data are not assigned to be compatible.
Two-Dimensional Boundary Layer Equations: High Resolution Capturing Methods
1993
In this paper we apply the piecewise hyperbolic and parabolic essentially non-oscillatory (ENO) capturing schemes (see [2] and [4]) to approximate the solution to the boundary layer equations for two-dimensional incompressible flow. We have tested several numerical examples analyzing their resolutive power and efficiency with respect to small values of the kinematic viscosity of the flow.
Boundary-layer Flows Past an Hemispherical Roughness Element: DNS, Global Stability and Sensitivity Analysis
2015
Abstract We investigate the full three-dimensional instability mechanism arising in the wake of an hemispherical roughness element immersed in a laminar Blasius boundary layer. The inherent three-dimensional flow pattern beyond the critical Reynolds number is characterized by coherent vortical structures called hairpin vortices. Direct numerical simulation is used to analyze the formation and the shedding of hairpin packets inside the shear layer. The first bifurcation characteristics are investigated by global stability tools. We show the spatial structure of the linear direct and adjoint global eigenmodes of the linearized Navier-Stokes operator and use structural sensitivity analysis to …
Las hormigas (Hymenoptera, Formicidae) asociadas a pulgones (Hemiptera, Aphididae) en la provincia de Valencia
2002
Twenty-six species of ants associated with aphids, belonging to twelve genera, are collected. Three subfamilies are identified, being the Formicinae the more represented about number of samples, genera and species. On the other hand, <i>Lasius niger</i> has been the species that is found with a more number of aphids (fifty eight species), and it seems to be the ant with a more capacity to establish associations with the different species of aphids. 224 different associations between the ants and the aphids are established and 164 of them are not recorded in the bibliography consulted for Spain.<br><br>Se han recogido veintiséis especies de hormigas asociadas a pulgon…
Fecundity determines the outcome of founding queen associations in ants
2021
AbstractAnimal cooperation evolved because of its benefits to the cooperators. Pleometrosis in ants - the cooperation of queens to found a colony - benefits colony growth, but also incurs costs for some of the cooperators because only one queen usually survives the association. While several traits are associated with queen survival, they tend to be confounded and it is unclear which factor specifically determines the outcome of pleometrosis. In this study, we used the ant Lasius niger to monitor offspring production in colonies founded by one or two queens. Then, we experimentally paired queens that differed in fecundity but not in size, and vice versa, to disentangle the effect of these f…
Yet another alien: a second species of Lepisiota spreading across the Canary Islands, Spain (Hymenoptera: Formicidae)
2018
The Canary Islands are a biologically important archipelago hosting many unique species, whose myrmecofauna is peculiarly rich in both endemic and introduced species. Lepisiota frauenfeldi cfr. kantarensis Forel, 1911 is reported for the first time from Fuerteventura and Tenerife. It is the second species of Lepisiota introduced in the archipelago in the last few years, and one of the few documented cases in which Lepisiota frauenfeldi (Mayr, 1855) s.l. acts as a successful tramp species. Comments are also given on taxonomic problems involving the L. frauenfeldi-group and related taxa. Finally, new additional information and comments are presented on the distribution of other alien ants spe…