Generalized covering designs and clique coverings

Inspired by the "generalized t-designs" defined by Cameron [P. J. Cameron, A generalisation of t-designs, Discrete Math. 309 (2009), 4835--4842], we define a new class of combinatorial designs which simultaneously provide a generalization of both covering designs and covering arrays. We then obtain a number of bounds on the minimum sizes of these designs, and describe some methods of constructing them, which in some cases we prove are optimal. Many of our results are obtained from an interpretation of these designs in terms of clique coverings of graphs.Comment: 30 pages, 1 figur

The basis of resilience in forest tree species and its use in adaptive forest management in Britain

Forest ecosystems face a range of challenges in the coming decades, of which climate change, pests and diseases are the most serious. These challenges will be overlaid on a background of historically modified and fragmented forests managed in a wide range of ways for different objectives. As northern temperate forests are species-poor in a global context, their resilience to these challenges is fundamentally dependent on the resilience of individual species. However, dealing with each new threat as it arises is unlikely to be cost effective and in any case, probably not practically feasible. A better strategy for establishing long term resilience would be to harness evolutionary processes, to maximise the capability of individual tree species to respond to new threats by the reorganisation of populations via natural selection; in other words, to be resilient. Such processes depend on the internal variability of species, their mechanisms of dispersal and their ability to recruit new genotypes to a population. In this paper we review the theoretical concept of resilience, examine how it might be applied to tree populations and assess the state of knowledge of Britain’s forests from this perspective

Cross-amplification and characterization of polymorphic microsatellite markers from Acacia (Senegalia) mellifera and Acacia brevispica to Acacia senegal (L.) Willd.

Seven polymorphic microsatellite markers isolated from Acacia brevispica and Acacia mellifera were successfully cross-amplified in Acacia senegal. The loci were surveyed for polymorphism using 30 samples. Allelic diversity ranged from 4 (Ame02, Ab06 and Ab18) to 13 (Ab26) per locus. The expected heterozygosity (HE) ranged from 0.543 (Ame02) to 0.868 (Ab26) while observed heterozygosity (HO) ranged from 0.516 (Ame05) to 0.800 (Ame03). Cross amplification of these loci represents a potential source of co-dominant marker and will be useful in the study of genetic diversity, structure, gene flow and breeding systems of this important Acacia species

On Determining Minimal Spectrally Arbitrary Patterns

In this paper we present a new family of minimal spectrally arbitrary patterns which allow for arbitrary spectrum by using the Nilpotent-Jacobian method. The novel approach here is that we use the Intermediate Value Theorem to avoid finding an explicit nilpotent realization of the new minimal spectrally arbitrary patterns.Comment: 8 page

Developing know-how for the improvement and sustainable management of teak genetic resources

The project had the following objectives: To trace and quantify genetic diversity of teak within its natural range, DNA markers were used to assay the current distribution of genetic diversity within and between populations, investigate its mating system and establish historical migration patterns. To evaluate the amount of contemporary gene flow through pollen and seed, hypervariable microsatellite DNA markers have been developed for parentage analysis. The molecular work was complemented by field observations of teak flower insect pollinators. To assess the influence of human disturbance, the genetic diversity in teak forests that have been undisturbed, lightly or heavily disturbed have been assessed and compared for both population genetic diversity and contemporary gene flow processes

Genetic considerations in ecosystem restoration using native tree species. State of the World’s Forest Genetic Resources – Thematic Study.

There is renewed interest in the use of native tree species in ecosystem restoration for their biodiversity benefits. Growing native tree species in production systems (e.g. plantation forests and subsistence agriculture) can also ensure landscape functionality and support for human livelihoods. Achieving these full benefits requires consideration of genetic aspects that are often neglected, such as suitability of germplasm to the site, quality and quantity of the genetic pool used and regeneration potential. Understanding the extent and nature of gene flow across fragmented agro-ecosystems is also crucial to successful ecosystem restoration. We review the role of genetic considerations in a wide range of ecosystem restoration activities involving trees and evaluate how different approaches take, or could take, genetic aspects into account, leading towards the identification and selection of the most appropriate methods

Understanding the evolution of native pinewoods in Scotland will benefit their future management and conservation

Scots pine (Pinus sylvestris L.) is a foundation species in Scottish highland forests and a national icon. Due to heavy exploitation, the current native pinewood coverage represents a small fraction of the postglacial maximum. To reverse this decline, various schemes have been initiated to promote planting of new and expansion of old pinewoods. This includes the designation of seed zones for control of the remaining genetic resources. The zoning was based mainly on biochemical similarity among pinewoods but, by definition, neutral molecular markers do not reflect local phenotypic adaptation. Environmental variation within Scotland is substantial and it is not yet clear to what extent this has shaped patterns of adaptive differentiation among Scottish populations. Systematic, rangewide common-environment trials can provide insights into the evolution of the native pinewoods, indicating how environment has influenced phenotypic variation and how variation is maintained. Careful design of such experiments can also provide data on the history and connectivity among populations, by molecular marker analysis. Together, phenotypic and molecular datasets from such trials can provide a robust basis for refining seed transfer guidelines for Scots pine in Scotland and should form the scientific basis for conservation action on this nationally important habitat

Anti-cancer effects and mechanism of actions of aspirin analogues in the treatment of glioma cancer

INTRODUCTION: In the past 25 years only modest advancements in glioma treatment have been made, with patient prognosis and median survival time following diagnosis only increasing from 3 to 7 months. A substantial body of clinical and preclinical evidence has suggested a role for aspirin in the treatment of cancer with multiple mechanisms of action proposed including COX 2 inhibition, down regulation of EGFR expression, and NF-κB signaling affecting Bcl-2 expression. However, with serious side effects such as stroke and gastrointestinal bleeding, aspirin analogues with improved potency and side effect profiles are being developed. METHOD: Effects on cell viability following 24 hr incubation of four aspirin derivatives (PN508, 517, 526 and 529) were compared to cisplatin, aspirin and di-aspirin in four glioma cell lines (U87 MG, SVG P12, GOS – 3, and 1321N1), using the PrestoBlue assay, establishing IC50 and examining the time course of drug effects. RESULTS: All compounds were found to decrease cell viability in a concentration and time dependant manner. Significantly, the analogue PN517 (IC50 2mM) showed approximately a twofold increase in potency when compared to aspirin (3.7mM) and cisplatin (4.3mM) in U87 cells, with similar increased potency in SVG P12 cells. Other analogues demonstrated similar potency to aspirin and cisplatin. CONCLUSION: These results support the further development and characterization of novel NSAID derivatives for the treatment of glioma