No description available.

The elm disease incited by Ceratocystis ulmi (Buism.) C. Moreau, generally named Dutch elm disease, especially in North America, was discovered in The Netherlands soon atter the first world war. The designation, Dutch elm disease, should be avoided, according to Westenberg (1932), because it is misleading. The name elm disease is used in this work, following in this respect the nomenclature adopted in the Annual Report of the Quebec Society for the Protection of Plants (Pomerleau, 1961). [...]

Pollen and charcoal percentage and concentration analyses have been conducted upon several upland peat profiles of late Flandrian II and early Flandrian III age at North Gill, North York Moors, where earlier research had proven recurrent major pre Elm Decline woodland disturbance, supported in one profile by radiocarbon dating. Fine temporal resolution pollen analysis (FRPA) involving the use of contiguous millimetre sampling was applied to Flandrian II disturbance phases at five of the North Gill profiles. At North Gill 1A a further phase of disturbance near the end of Flandrian II was examined using FRPA to study evidence of pre Elm Decline agricultural activity, and at this profile both the horizontal and vertical resolution limits of the technique were tested by progressively finer sub-sampling. The millimetre level FRPA analyses showed that each of the examined pre Elm Decline disturbance phases was an aggregate feature, composed of a number of smaller sub-phases, the ecological effects of which in terms of spatially-precise woodland successions and community structures were assessed and contrasted. Inter-profile spatial comparison of the ecology of woodland disturbances has been made at both FRPA and conventional scales of temporal resolution. FRPA study of the late Flandrian II disturbance phase at North Gill 1A showed that cereal cultivation had occurred prior to the Elm Decline as part of a multi-phase period of agricultural land-use activity. The high resolution spatial and temporal data from North Gill have shown FRPA to be a most sensitive palaeoecological technique, and are discussed in relation to the effects of disturbance upon mire and woodland ecosystems, Mesolithic land-use, pre Elm Decline cereal cultivation and early Neolithic land-use.

Dutch elm disease (DED) is a debilitating wilt disease that has decimated elm populations globally. The current pandemic of this disease is caused by the ascomycete fungal pathogen Ophiostoma novo-ulmi. A number of strategies have been used to attempt to mitigate the effects of DED but none have met any sustainable success, and the disease continues to have severe ecological and economic impacts. Consequently, research focus has turned to the development of control strategies at the genetic level. One such genetic strategy is the use of naturally occurring fungal viruses (mycoviruses) to induce hypovirulence in their fungal hosts. Hypovirulence, or attenuation of fungal pathogenicity using mycoviruses, has been well studied in other systems but has yet to be developed for O. novo-ulmi. A candidate virus, OnuMV1c, was found in an isolate of O. novo-ulmi (93-1224) at the western Canadian disease front and its genome was sequenced. OnuMV1c is a mitochondrial virus and has a 3.1 kb single-stranded positive RNA genome that encodes an RNA-dependent RNA polymerase (RdRp) involved in its replication as a double-stranded RNA molecule. It exists in O. novo-ulmi mitochondria in both its single-stranded and double-stranded forms. Our research group identified OnuMV1c as a potential candidate for biological control of Dutch elm disease. Our long-term research goal is to use the virus as a means to activate the RNA interference pathway of O. novo-ulmi, leading to down-regulation of genes involved in pathogenicity. If OnuMV1c is engineered such that it carries an RNA interference cassette in addition to its own complement of genes, it could act as an enhanced hypovirus. RNA interference (RNAi) is a cytoplasmic process, and therefore in order to use OnuMV1c for RNAi the viral genome needed to be reprogrammed such that it could be expressed in the cytoplasm rather than the mitochondria. The objectives of my master’s research were to 1) genetically engineer OnuMV1c to express in the cytoplasm using a cDNA reverse genetics approach, and 2) test the functionality of the re-engineered cDNA OnuMV1c virus (MV1cCyt). The first objective was accomplished by modifying codons in the RdRp sequence of OnuMV1c such that the sequence could be translated in the cytoplasm. This genetically engineered cytoplasmic version of OnuMV1c, named MV1cCyt, was flanked with exogenous promoter and terminator sequences to drive its transcription. The entire construct was engineered as a cDNA molecule and was cloned into the fungal transformation vector pAN7-1, which was used to transform O. novo-ulmi protoplasts. The second objective was achieved through the use of strand-specific RT-PCR, a technique that allowed the detection of both the positive and negative strands of MV1cCyt. Results indicated that while four individual cell lineages contained MV1cCyt cDNA stably integrated into the nuclear genome, only one transformant was able to produce double-stranded MV1cCyt RNA. These results have important implications for the use of OnuMV1c as an engineered hypovirus and represent the first step towards the development of a biological control strategy for Dutch elm disease. / Graduate

This thesis aims at investigate the feasibility of classifying the soprano singing voice type using a single layer neural network trained with the FIR-ELM algorithm after that the monaural auditory mixture has been segmented with the Harmonic, Percussive and Residual, HPR, decomposition algorithm, previously introduced by Driedger et al.Two different decomposition structures has been evaluated both based on the same HPR decomposition technique. Firstly one single layer that only take advantage of the result of the more pure harmonic and the more pure percussive components of the signal. Secondly, one multilayer structure that further decompose both the harmonic and the percussive components but also takes into account the components that can not be clearly categorized as neither harmonic or percussive components, these are the residual components. The result of the classification was up to 98.5 $\%$ after using these segmentation techniques, this shows that it is feasibly to classify the singing voice type soprano in an monaural source recorded in a non-professional environment using the FIR-ELM algorithm.

No description available.

No description available.

No description available.

No description available.

It was the purpose of this investigation to attempt to demonstrate if differences in eutrophic levels existed among selected areas of Garza-Little Elm, and to demonstrate the role that sediments play in affecting eutrophication.