Brick assignments and homogeneously almost self-complementary graphs

AbstractA graph is called almost self-complementary if it is isomorphic to the graph obtained from its complement by removing a 1-factor. In this paper, we study a special class of vertex-transitive almost self-complementary graphs called homogeneously almost self-complementary. These graphs occur as factors of symmetric index-2 homogeneous factorizations of the “cocktail party graphs” K2n−nK2. We construct several infinite families of homogeneously almost self-complementary graphs, study their structure, and prove several classification results, including the characterization of all integers n of the form n=pr and n=2p with p prime for which there exists a homogeneously almost self-complementary graph on 2n vertices

Characteristics of heteroblasty in Hladnikia pastinacifolia (Apiaceae), a rare endemic from Slovenia

Hladnikia pastinacifolia, the most prominent endemic plant species in Slovenia, is rare and protected because it is a stenoendemic and paleoendemic species restricted to area of Trnovski gozd (W Slovenia). However, this species can be found in various habitats. The disparity between the nonspecific habitat preference of the species and its rarity has not been sufficiently explained. Here we focus on the functional morphological features that are most indicative for the ecology of plant species: the anatomical and morphological characteristics of leaves. Hladnikia pastinacifolia exhibits heterophylly during ontogeny (heteroblasty). We aimed to describe and compare the anatomical characteristics of three H. pastinacifolia leaf morphotypes among them and in relation to various habitats. Therefore, we compared leaf functional features that are indicative for the ecology of plant species: the thickness of the leaf lamina, the spongy and palisade parenchyma, the thickness of the upper and lower epidermis and the number of leaf stomata in the upper and lower epidermis. These measurements were further used to calculate the ratio between the spongy and palisade parenchyma, leaf stomata index and the density of leaf stomata. We determined that the H. pastinacifolia heteroblasty belongs to the Apium-type. Results showed that the five-pinnate leaves were the most distinct type, being the thickest, with the highest numbers of stomata abaxially. When compared among habitats, leaves from the scree habitat were the thickest according to all the tissue layers studied. The indices calculated were less useful for the distinction between leaf types and habitats

The directed Oberwolfach problem with variable cycle lengths: a recursive construction

The directed Oberwolfach problem OP$^\ast(m_1,\ldots,m_k)$ asks whether the complete symmetric digraph $K_n^\ast$, assuming $n=m_1+\ldots +m_k$, admits a decomposition into spanning subdigraphs, each a disjoint union of $k$ directed cycles of lengths $m_1,\ldots,m_k$. We hereby describe a method for constructing a solution to OP$^\ast(m_1,\ldots,m_k)$ given a solution to OP$^\ast(m_1,\ldots,m_\ell)$, for some $\ell<k$, if certain conditions on $m_1,\ldots,m_k$ are satisfied. This approach enables us to extend a solution for OP$^\ast(m_1,\ldots,m_\ell)$ into a solution for OP$^\ast(m_1,\ldots,m_\ell,t)$, as well as into a solution for OP$^\ast(m_1,\ldots,m_\ell,2^{\langle t \rangle})$, where $2^{\langle t \rangle}$ denotes $t$ copies of 2, provided $t$ is sufficiently large. In particular, our recursive construction allows us to effectively address the two-table directed Oberwolfach problem. We show that OP$^\ast(m_1,m_2)$ has a solution for all $2 \le m_1\le m_2$, with a definite exception of $m_1=m_2=3$ and a possible exception in the case that $m_1 \in \{ 4,6 \}$, $m_2$ is even, and $m_1+m_2 \ge 14$. It has been shown previously that OP$^\ast(m_1,m_2)$ has a solution if $m_1+m_2$ is odd, and that OP$^\ast(m,m)$ has a solution if and only if $m \ne 3$. In addition to solving many other cases of OP$^\ast$, we show that when $2 \le m_1+\ldots +m_k \le 13$, OP$^\ast(m_1,\ldots,m_k)$ has a solution if and only if $(m_1,\ldots,m_k) \not\in \{ (4),(6),(3,3) \}$

Additional records of Megabruchidius dorsalis (Fåhræus, 1839) (Coleoptera, Chrysomelidae, Bruchinae) in Zagreb, Croatia

In this paper, we report two new locations of the alien invasive seed beetle Megabruchidius dorsalis in Zagreb, Croatia. Additionally, we confirm for the second time the presence of M. dorsalis at one location in the same city. All beetles were reared from mature Gleditsia triacanthos pods collected from the ground (three locations) and from trees (one location). These records contribute to the knowledge of the distribution of M. dorsalis in Europe

Prisutnost stranih vrsta Prunus serotina i Impatiens parviflora u fragmentima nizinskih šuma u SI Sloveniji

Temperate alluvial, riparian and lowland forests are the European forests with the greatest presence of invasive alien plants. Consequently, identifying the environmental conditions for and other drivers behind the establishment of invasive species in natural forest communities is crucial for understanding the invasibility of these habitats. We focused on fragments (patches) of Illyrian oak-hornbeam forest in NE Slovenia, which are the least studied in this regard.Because alien phanerophytes and therophytes are significantly over-represented compared to native plants in lowland forests, we selected two representative invasives: the phanerophyte Prunus serotina and the therophyte Impatiens parviflora. By using logistic regression models on vegetation surveys, environmental data based on Ellenberg´s indicator values, and patch metrics, we identified patch characteristics explaining the presence of each species. Moreover, we included human impact in the models.We reveal significant characteristics differentiating P. serotina from I. parviflora. We also show that the perimeter-area ratio and soil nutrients of the forest patches correlate significantly with the presence of P. serotina, while human disturbance correlates significantly with the presence of I. parviflora. Our results and a similar approach for other invasive plant species can be applied to assess habitat invasibility on potential and species’ current geographic distribution, as well as to develop management plans.Aluvijalne, priobalne i nizinske šume umjerenih područja europske su šume s najvećom prisutnošću invazivnih stranih biljaka. Slijedom toga, utvrđivanje okolišnih uvjeta i drugih pokretača invazije tih vrsta u prirodnim šumskim zajednicama presudno je za razumijevanje izloženosti ovih sta­ni­šta invazivnim vrstama. Fokusirali smo se na fragmente ilirske šume hrasta kitnjaka i običnog graba u SI Sloveniji, koje su u tom pogledu najmanje proučavane.Budući da su alohtoni fanerofiti i terofiti znatno prezastupljeni u usporedbi s autohtonim vrstama u nizinskim šu­ma­ma, odabrali smo dvije reprezentativne invazivne vrste: fanerofit Prunus serotina i terofit Impatiens parviflora. Kori­šte­njem logističkih regresijskih modela na vegetacijskim podacima, okolišnim podacima na temelju Ellenbergovih indikatorskih vrijednosti i krajobrazne metrike na razini fragmenata (zakrpi), identificirali smo karakteristike fragmenata šumske vegetacije koji objašnjavaju prisutnost svake vrste. Štoviše, u modele smo uključili utjecaj čovjeka.Otkrivene su značajne karakteristike koje međusobno razlikuju invazivnost vrsta P. serotina i I. parviflora. Također pokazalo se da omjer površine i hranjive tvari šumskih fragmenata značajno koreliraju s prisutnošću vrste P. serotina, dok antropogeni poremećaj staništa značajno korelira s prisutnošću vrste I. parviflora. Naši rezultati te sličan pristup za druge invazivne biljne vrste mogu se primijeniti za procjenu podložnostistaništa na potencijalnu i trenutnu rasprostranjenost tih vrsta, kao i za izradu planova upravljanja

ARCHES D14 - Recommendations for the use of UHPFRC in composite structural members – rehabilitation Log Čezsoški bridge

The increasing volume of European transport urgently requires an effective road and rail system in Central European and Eastern Countries (CEEC) with a major investment in building new and assessing and rehabilitating old structures. Following 5 successful applications of rehabilitation with Ultra High Performance Fibre Reinforced Concretes in Switzerland, since 2004, the same concept was applied to a bridge in Slovenia in July 2009 with new UHPFRC mixes from local products. An innovative concept of cement replacement by high dosages of limestone filler, developed at EPFL, helped break the workability barrier and produce a Slovenian UHPFRC with local cement (SALONIT), and superplasticiser (TKK), The material has excellent rheological properties and was tailored to be applied on slopes up to 5 %, without sacrificing the protective function and mechanical properties. The full section of the deck and footpaths of the 65 m span Log Čezsoški bridge over Soča river in Slovenia was cast in one step, over two days for the full length. An original combination of UHPFRC with Controlled Permeability Formwork (CPF) membrane (ZEMDRAIN®) developed at ZAG helped produce finished footpath surfaces ready to walk barefoot which was one of the challenges set by the owner. The specially tailored thixotropic mix held the 5 % slope without difficulties. The newly designed ECO-UHPFRC recipes have a dramatically reduced cement content which makes them more economical and particularly attractive from an environmental point of view. Over the whole life cycle, rehabilitations with ECO-UHPFRC have a much lower impact than traditional methods. This successful example of transfer of technology opens up very promising perspectives for the dissemination of this new concept of rehabilitation of civil infrastructures not only in New Member States (which was the goal of the project ARCHES) but also in virtually any country