A graph is a cactus if any two of its cycles have at most one common vertex. In this paper, we determine the first sixteen largest Laplacian spectral radii together with the corresponding graphs among all connected cacti with n vertices and k cycles, where n > 2k + 8.

A cactus is a connected graph in which any two cycles have at most one vertex in common. We determine the unique graphs with maximum signless Laplacian spectral radius in the class of cacti with given number of cycles (cut edges, respectively) as well as in the class of cacti with perfect matchings and given number of cycles.

Experiments were performed to study the effect of measurement duration on palatability of eleven range species and to define thereafter a palatability index. The range species were randomly distributed in five combinations (C l to C5) containing each four species. Each combination was tested over a15-day experimental period on four one-year old sheep and five two-year old one-humped camels (cam...

The stress gradient hypothesis posits that facilitation and stress are positively correlated. The hump-shaped hypothesis, on the contrary, proposes that facilitation is greater at intermediate stress levels. The relationship between facilitation and environmental stress is commonly studied at small spatial scales and/or considering few species; thus, the implications of facilitation at a commun...

We present a revised molecular phylogeny of the Drosophila repleta group including 62 repleta group taxa and nine outgroup species based on four mitochondrial and six nuclear DNA sequence fragments. With ca. 100 species endemic to the New World, the repleta species group represents one of the major species radiations in the genus Drosophila. Most repleta group species are associated with cacti ...

Although plastid DNA has been widely explored as a marker of choice for phylogeny and phylogeography studies, little is known about its utility for examining relationships between closely related species. The slow evolutionary rates inherent to chloroplast (cp) DNA make it difficult to perform lower level taxonomic analyses, particularly at the population level. We characterized the nucleotide ...

The Bethe algebras for the Gaudin model act on the multiplicity space of tensor products of irreducible glr-modules and have simple spectrum over real points. This fact is proved by Mukhin, Tarasov and Varchenko who also develop a relationship to Schubert intersections over real points. We use an extension to M0,n+1(R) of these Schubert intersections, constructed by Speyer, to calculate the mon...

This new species (Phthiria sharafi sp. nov.) represents the first record of the subfamily Phthiriinae (Bombyliidae, Diptera) from Saudi Arabia. The species was collected from Garf Raydah Protected Area, Abha, Asir Province, south-western part of Saudi Arabia, using a Malaise trap erected in a site rich in olive, cactus and Juniper trees. The type locality has an Afrotropical influence, with the...

Recent studies have demonstrated significant correlations between stem and leaf hydraulic properties when comparing across species within ecological communities. This implies that these traits are co-evolving, but there have been few studies addressing plant water relations within an explicitly evolutionary framework. This study tests for correlated evolution among a suite of plant water-use tr...