Genetic diversity and gene flow in fragmented populations of the rare shrub, Calothamnus sp. Whicher

Ca/othamnus sp. Whicher (Myrtaceae) is a narrow range endemic shrub restricted to ironstone soils near the town of Busselton in south-western Australia. Due to extensive land clearing for agriculture and mineral exploration, the species is fragmented over the majority of its range. In the present study, microsatellite markers were used to characterise levels of genetic diversity and describe levels of differentiation and gene flow among seven small, isolated road verge populations. Allelic diversity within the taxon over the six microsatellites was high (A = 17.6 ± 1.6). Diversity within populations was considerably lower (A = 5.19 ± 1.27), and was positively correlated with population size. An excess of homozygotes and high fixation indices in all populations (mean FIS = 0.315 ± 0.13) indicated that inbreeding within populations was high. Estimates of the divergence in allele frequencies between populations (global θ = 0.256) and genetic distance (mean Nei\u27s D = 0.370) revealed a distinct genetic structure within the study sample. Direct estimates of gene flow, determined by assigning paternity to seed crops from the two largest populations, were low (2.7% and 4%), yet similar to historical estimates derived from the degree of differentiation between populations. However, due to the degree of inbreeding within these populations and their susceptibility to genetic drift, these historical estimates appeared to be a consequence of post fragmentation rates of gene flow rather than reflecting pre-fragmentation rates. Low levels of gene flow into the two largest populations and restricted within population patterns of mating were supported by high global (among population) and mean pairwise (within population) estimates of Φft, which represents the degree of differentiation between maternally sampled pollen pools. The differentiation observed between populations is most likely a result of postfragmentation processes rather than being driven by mutation and maintained by low levels of historical gene flow. The six natural road verge populations observed in this study were likely to be part of one or more larger, continuous populations similar to those which are located in relatively undisturbed fragments of natural vegetation. Initially, differentiation within these populations probably resulted from their small sizes and the heterogeneous fine scale genetic structure within the larger population(s) from which they originated. Further differentiation appears to have resulted from· ·extensive inbreeding within populations and the increased vulnerability to drift associated with decreasing population size. Results from other studies, including that conducted on the closely related species Calothamnus quadrifidus (Byrne et al., in press), suggest that fragmentation has reduced rates of gene flow from higher historical levels. However, the detection of some gene flow events across the breadth of the study site suggests that isolation itself was not preventing gene flow. Rather, the loss of natural vegetation may have reduced the abundance of bird pollinators. The conservation and evolutionary implications of these findings are discussed

Target Detection in Heterogeneous Clutter with Low Resolution Radar

This thesis develops a framework for SAR target detection and super-resolution in low-resolution environments. The primary focus in this research is the background clutter heterogeneity that often accompanies low range and cross-range resolutions. A corrective model which accounts for clutter replacement is developed to define the detection and false alarm rates of the detector more accurately than a traditional model in which the radar return from the target supplements the existing clutter. In a heterogeneous clutter cell, the clutter replacement model leverages the different scattering distributions among the individual clutter types to generate a probability distribution function for the areas of each clutter type which are obstructed by a target. The location of the target can be extrapolated from the clutter replacement areas, and a multiple hypothesis detection test is conducted to determine which location estimate yields the lowest average error

The crust structure of the Morasko meteorite – a preliminary hypothesis

A small piece of the Morasko meteorite, weighing 970 g, yields traces of its journey through the Earth’s atmosphere and of its impact into a mineral substrate, such as reflected in the meteorite’s crust. This is seen in the crust structure in the form of sintered as well as fusion and semi-fusion layers for which ablative niches are optimum sites. Subsequent weathering processes have resulted in significant mineralogical changes in the crusts. The meteorite crusts originated during polygenetic processes

Hierarchical fast selection of intraframe prediction mode in HEVC

In the new HEVC standard, there are 35 intraframe prediction modes. Therefore, real-time implementations need fast mode pre-selection to reduce the computational load of cost comparison for individual modes. In this paper, a simple technique is proposed to reduce the complexity of the Unified Intra Prediction by decreasing the mode candidate number evaluated in the Rough Mode Decision step. We call this approach hierarchical as we decrease stepwise the angles between the directions of the prediction modes that are tested. Obviously, the fast mode selection results in significant complexity reduction obtained at the cost of choosing a sub-optimum mode related to slightly reduced compression performance. In the paper, it is proposed how to calculate the trade-off between encoder complexity and compression performance, using the ratio of relative coding time reduction and average bitrate increase estimated for constant decoded video quality. Extensive experiments prove that this ratio is much higher for the proposed technique than for many other techniques from the references

Speciation in marine environments: Diving under the surface

Marine environments are inhabited by a broad representation of the tree of life, yet our understanding of speciation in marine ecosystems is extremely limited compared with terrestrial and freshwater environments. Developing a more comprehensive picture of speciation in marine environments requires that we 'dive under the surface' by studying a wider range of taxa and ecosystems is necessary for a more comprehensive picture of speciation. Although studying marine evolutionary processes is often challenging, recent technological advances in different fields, from maritime engineering to genomics, are making it increasingly possible to study speciation of marine life forms across diverse ecosystems and taxa. Motivated by recent research in the field, including the 14 contributions in this issue, we highlight and discuss six axes of research that we think will deepen our understanding of speciation in the marine realm: (a) study a broader range of marine environments and organisms; (b) identify the reproductive barriers driving speciation between marine taxa; (c) understand the role of different genomic architectures underlying reproductive isolation; (d) infer the evolutionary history of divergence using model‐based approaches; (e) study patterns of hybridization and introgression between marine taxa; and (f) implement highly interdisciplinary, collaborative research programmes. In outlining these goals, we hope to inspire researchers to continue filling this critical knowledge gap surrounding the origins of marine biodiversity

Rozważania na temat przyczyn powstawania stwardnienia rozsianego i leczenia

Sclerosis multiplex (SM) is considered as a immunologic disease, which pathogenesis still remains unknown— it is therefore difficult to choose the optimal method of treatment. The aim of this review is to analyzethe vascular theory of pathogenesis of SM and possibilities of new therapeutic options of the disease. Surprisingis the number of common elements both in the vascular theory of SM, and the effects of subarachnoidhaemorrhage. Additionally, in light of current research studies, it apears that responsible for the neurologicaldetoriation after SAH is not just reactive arterial narrowing, but rather the local inflammatory responsegenerated by the extravasated blood. It seems to be a logical proposal to use the similar treatment in theacute MS relapse as the nimodipine treatment for acute neurological deterioration after SAH.Stwardnienie rozsiane jest uważane za chorobę demielinizacyjną o podłożu immunologicznym, niejasnapozostaje jednak nadal jego patogeneza, zatem wybór optymalnej metody postępowania jest trudny. Celemniniejszej pracy jest analiza teorii naczyniowej patogenezy SM oraz ewentualnych nowych opcji terapeutycznych.Zaskakująca jest liczba elementów wspólnych dla teorii naczyniowej SM, jak również efektów uszkodzenianaczyń mózgowych w przebiegu krwawienia podpajęczynówkowego. Dodatkowo, w odniesieniu do aktualnychbadań za zły stan kliniczny chorych po SAH wydaje się odpowiadać nie tyle reaktywne zwężenie naczyńtętniczych, co miejscowa reakcja zapalna powstająca w wyniku działania wynaczynionej krwi. Logiczna wydajesię zatem propozycja zastosowania m.in. nimodypiny w ostrych rzutach SM leczenia podobnego jak terapiaostrego pogorszenia stanu neurologicznego w SAH

The aerodynamic effects of VHBR engine installation to the Common Research Model

This work describes the assessment of the effect of engine installation parameters such as engine position, size and power setting on the performance of a typical 300 seater aircraft at cruise condition. Two engines with very-high by-pass ratio and with different fan diameters and specific thrusts are initially simulated in isolation to determine the thrust and drag forces for an isolated configuration. The two engines are then assessed in an engine-airframe configuration to determine the sensitivity of the overall installation penalty to the vertical and axial engine location. The breakdown of the interference force is investigated to determine the aerodynamic origins of beneficial or penalising forces. To complete the cruise study a range of engine power settings were considered to determine the installation penalty at different phases of cruise. This work concludes with the preliminary assessment of cruise fuel burn for two engines. For the baseline engine, across the range of installed positions the resultant thrust requirement varied by 1.7% of standard net thrust. The larger engine was less sensitive with a variation of 1.3%. For an assessment over a 10000km cruise flight the overall effect of the lower specific thrust engine showed that the cycle benefits of –5.8% in specific fuel consumption was supplemented by a relatively beneficial aerodynamic installation effect but offset by the additional weight to give a -4.8% fuel burn reduction