Since its discovery, the phenomenon of nuclear fission is the object of extensive theoretical and experimental studies. However, we are still far from a complete understanding of the fission process. Nuclear theory can satisfactorily explain the process of neutron-induced fission at thermal neutron energies, but it meets problems at high neutron energies. However, new applications are nowadays developed involving neutron-induced fission in this energy domain. An example of such an application is accelerator-driven systems (ADS) which are dedicated to transmutation of highly radioactive nuclear waste. Conceptual studies of ADS require new nuclear data on neutron-induced reactions within a wide incident energy range. Along with structural, spallation target and other materials, data on neutron-induced fission are especially required for two nuclides, 232Th and 238U. At present, however, there are no published neutron-induced fission yield data for either 232Th or 238U at energies above 20 MeV. In this thesis, I present measurements of fission fragment mass yields at neutron energies from 10 to 60 MeV for 232Th and 238U. The experiment was done at the Louvain-la-Neuve quasi-monoenergetic neutron beam facility. A multi-section Frisch-gridded ionization chamber was used as the fission fragment detector. The fission fragment mass yields were measured at peak neutron energies of 33, 45, and 60 MeV. In addition, data for the neutron-energy intervals 9-11, 16-18, and 24-26 MeV were also extracted from the low-energy tail. The measurement results show that the symmetric fission component increases with incident neutron energy for both uranium and thorium, but it is more enhanced for thorium. The uranium results were compared to the only existing set of experimental data for neutron energies above 20 MeV. Reasonable agreement was found. However, our data show a lower symmetric fission component. For thorium, the present data are the first above 20 MeV. Model calculations with the TALYS code have also been done. This code is based on the multi-modal random neck-rupture model extended for higher excitation energies. We included a phenomenological model into the code and achieved a good description of our experimental results. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 723

The past decade has seen a tremendous growth in the amount of biomedical literature, specifically in the area of bioinformatics. As a result, biomedical text categorization has become a central task for providing researchers with literature appropriate for their specific information needs. Pan et al. have explored a method that automatically identifies information-bearing sentence fragments within scientific text. Their proposed method aims to automatically classify sentence fragments into certain sets of categories defined to satisfy specific types of information needs. The categories are grouped into five different dimensions known as Focus, Polarity, Certainty, Evidence, and Trend. The reason that fragments are used as the unit of classification is that the class value along each of these dimensions can change mid-sentence. In order to automatically annotate sentence fragments along the five dimensions, automatically breaking sentences into fragments is a necessary step. The performance of the classifier depends on the sentence fragments. In this study, we investigate the problem of automatic fragmentation of biomedical sentences, which is a fundamental layer in the multi-dimensional fragment classification. In addition, we believe that our proposed fragmentation algorithm can be used in other domains such as sentiment analysis. The goal of sentiment analysis is often to classify the polarity (positive or negative) of a given text. Sentiment classification can be conducted at different levels such as document, sentence, or phrase (fragment) level. Our proposed fragmentation algorithm can be used as a prerequisite for phrase-level sentiment categorization which aims to automatically capture multiple sentiments within a sentence. / Thesis (Master, Computing) -- Queen's University, 2009-09-25 10:08:04.429

An immunoglobulin (IgG) consists of two antigen-binding fragments (Fab) connected to a crystallisable fragment through hinge regions. This thesis mainly investigates the production methods of Fabs used in structural studies. A cost effective and time saving protocol has been established for the production of recombinant 2F5 Fab, a HIV-1 broadly neutralizing monoclonal antibody fragment, using an Escherichia coli expression system. The integrity of structure and antigen-binding capability of the produced 2F5 Fab was confirmed by determining the crystal structure of the Fab-antigen peptide complex. In parallel, 3H1 Fab, a fragment of an antibody which is involved in detecting misfolded superoxide dismutase, which is related to familial amyotrophic lateral sclerosis, was produced by papain proteolysis of its parent IgG molecule. Both Fab production methods resulted in high yields of pure Fab samples that are crystallisable and ready to be engaged in structural studies using X-ray crystallography.

An immunoglobulin (IgG) consists of two antigen-binding fragments (Fab) connected to a crystallisable fragment through hinge regions. This thesis mainly investigates the production methods of Fabs used in structural studies. A cost effective and time saving protocol has been established for the production of recombinant 2F5 Fab, a HIV-1 broadly neutralizing monoclonal antibody fragment, using an Escherichia coli expression system. The integrity of structure and antigen-binding capability of the produced 2F5 Fab was confirmed by determining the crystal structure of the Fab-antigen peptide complex. In parallel, 3H1 Fab, a fragment of an antibody which is involved in detecting misfolded superoxide dismutase, which is related to familial amyotrophic lateral sclerosis, was produced by papain proteolysis of its parent IgG molecule. Both Fab production methods resulted in high yields of pure Fab samples that are crystallisable and ready to be engaged in structural studies using X-ray crystallography.

This project was aimed at investigating behaviour and condition of the Yellow-breasted Boubou, Laniarius atroflavus, in response to habitat differences across core, edge and riparian Afro-montane forest habitats at the Ngel Nyaki Forest Reserve, Nigeria. This species is little known and conservation effort will require direction in identifying the habitat of best quality for their survival. The determination of habitat association using correspondence analysis of census data suggested strongest association with the riparian habitat, even though this habitat held the least overall avian biodiversity as determined from a modified Shannon index. L. atroflavus appeared not to hold territories in the core habitat. Territoriality, vocalisation and time budget showed trends indicating L. atroflavus were more abundant and fared better in the riparian habitat. In this habitat, there was a greater density of territories and a smaller mean territory size, better call quality in frequency bandwidth and duration, and increased displaying and foraging time in the riparian habitat. Difference in size, colour and growth-based measures of condition showed difference between sexes, but did not show a strong habitat effect – males were larger than females, yet females appeared to have better quality of yellow breast feathers for equal carotenoid concentration. The effect of nest predation risk as a predictor of habitat quality revealed nests in the riparian habitat had the greatest daily survival probability, and within this habitat nests established at lower heights survived longest. While the evidence pointed towards the riparian habitat being most suitable for L. atroflavus, this habitat sadly continues to suffer anthropogenic disturbance and this species’ IUCN listing as Least Concern was suspected be an over-estimation.

Standardization, flexibility and transparency had been the eminent keywords of Modern Architecture that have also provided material for the re-interpretation and re-production of several discussions on concepts like &lsquo / form&rsquo / and &lsquo / function&rsquo / in architecture. This study is an inquiry into a number of different interpretations that scrutinize the intricate relationship between architectural form and function in the 20th century with respect to the concepts defined above. The conceptualization of this thesis will be based on the assumption that function is an inadequate and weak concept for the generation of architectural form. It is in this context that form is accepted as an architectural &ldquo / fragment&rdquo / that attains its autonomy not from the strictures imposed by other architectural fragment like &lsquo / function&rsquo / , &lsquo / structure&rsquo / , &lsquo / program&rsquo / and &lsquo / site / but from an infinite number of internal relationships or &lsquo / design tools&rsquo / as we call. The aim of this study is to propose a project for &ldquo / A Multi &ndash / Functional Hall at METU&rdquo / which has the capability of expanding its limits in future, both physically and conceptually / and investigate the &lsquo / design tools&rsquo / that will direct the steps of transformations in the process of architectural production. Within this framework, the investigation is concerned with the production of a flexible, unstable and indeterminant building, focused on the concepts of &lsquo / transformation of space&rsquo / and &lsquo / constant change&rsquo / , that could be re-designed and re-generated in respect to possible future transformations in the program. Thus, architectural production is defined merely as a &lsquo / step&rsquo / or a &lsquo / snap-shot&rsquo / , controlled by the design tools suggesting the solutions for an ever-lasting transformation as the conditions change.

As of today, there are 25 drugs approved for the treatment of HIV and AIDS. Nevertheless, HIV continues to infect and kill millions of people every year. Despite intensive research efforts, both a vaccine and a cure remain elusive and the long term efficacy of existing drugs is limited by the development of resistant HIV strains. New drugs and preventive strategies that are effective against resistant virus are therefore still needed. In this thesis an enzymological approach, primarily using SPR-based interaction kinetic analysis, has been used for identification and characterization of compounds of potential use in next generation anti-HIV drugs. By screening of a targeted non-nucleoside reverse transcriptase inhibitor (NNRTI) library, one novel and highly potent NNRTI was identified. The inhibitor was selected with respect to resilience to drug resistance and for high affinity and slow dissociation – a kinetic profile assumed to be suitable for inhibitors used in topical microbicides. In order to confirm the hypothesis that such a kinetic profile would result in an effective preventive agent with long-lasting effect, the correlation between antiviral effect and kinetic profile was investigated for a panel of NNRTIs. The kinetic profiles revealed that NNRTI efficacy is dependent on slow dissociation from the target, although the induced fit interaction mechanism prevented quantification of the rate constants. To avoid cross-resistance, the next generation anti-HIV drugs should be based on chemical entities that do not resemble drugs in clinical use, either in structure or mode-of-action. Fragment-based drug discovery was used for identification of structurally new inhibitors of HIV-enzymes. One fragment that was effective also on variants of HIV RT with resistance mutations was identified. The study revealed the possibility of identifying structurally novel NNRTIs as well as fragments interacting with other sites of the protein. The two compounds identified in this thesis represent potential starting points for a new generation of NNRTIs. The applied methodologies also show how interaction kinetic analysis can be used as an effective and versatile tool throughout the lead discovery process, especially when integrated with functional enzymological assays.

The specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family – an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity. Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable. Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other. The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct. In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination. Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species. An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stabilityof the Western Australian landscape. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs.

Diss.--Université--Fribourg, Suisse, 1990.

Made available in DSpace on 2014-06-11T19:23:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-27Bitstream added on 2014-06-13T20:10:55Z : No. of bitstreams: 1 martins_la_me_botfca.pdf: 9668913 bytes, checksum: 69b87662a1dd037524113f277bfdba4c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A Mata Atlântica é um dos biomas de maior biodiversidade do planeta, que há séculos tem sido sistematicamente destruída pelo desmatamento e fragmentação florestal, principalmente no domínio da Floresta Estacional Semidecidual. Os fragmentos remanescentes frequentemente têm sofrido distúrbios adicionais, tanto antrópicos quanto naturais. Deste modo, para a sua conservação e restauração é fundamental o conhecimento da resposta desses ecossistemas aos distúrbios. Este trabalho teve como objetivo geral caracterizar a estrutura da vegetação e a regeneração natural de um fragmento de floresta estacional semidecidual com diferentes históricos de perturbações e conhecer o papel das clareiras na regeneração de algumas das suas espécies arbóreas mais representativas. A pesquisa foi realizada em um fragmento de floresta estacional semidecidual com aproximadamente 615 ha (Reserva Particular do Patrimônio Natural (RPPN) Olavo Egydio Setúbal), no município de Lençóis Paulista (22. 27’S, 48.57W), SP. A amostragem foi feita através da demarcação de parcelas permanentes contíguas (10 x 10 m), totalizando um hectare em cada uma de três área na floresta( três hectares no total), sendo: área A , local que sofreu efeitos de um tornado ocorrido há cinco anos atrás; área B: área mais bem conservada, sem histórico recente de perturbações antrópicas e, área C, com registros de extração seletiva de madeira até meados da década de 70. Em cada área foram sorteadas 50 parcelas de 10 x 10 m para o levantamento fitossociológico do estrato arbóreo (indivíduos com altura 1,30 m) e regenerante (altura 0,50 e <1,30 m, levantado em 3 sub-parcelas de 10 x 1 m). Para a regeneração natural, cada subparcela amostrada foi categorizada como sendo de clareira (definição de Brokaw, 1982) ou de dossel fechado. O monitoramento do microclima foi feito quatro vezes... / The Atlantic Forest is one of the richest planest’s biomes in biodiversity, which has been systematically destroyed by deforestation and forest fragmentation., mainly at the Seasonal Semideciduous Forest domain. The remaining forest fragments have often suffered further disturbances , be natural or anthropogenic. To conserve or restore these ecosystems is fundamental to know how do they respond to the disturbances. This paper has the objective of characterizing the vegetation structure and the natural regeneration of a forest fragment with different disturbances histories, assessing the role of gaps in the regeneration of its most representatives tree species..The research was realized in a 615 ha seasonal semideciduous forest fragment (Private Natural Patrimony Reserve-RPPN “Olavo Egydio Setúbal”), at Lençóis Paulista Municipality (22. 27’S, 48.57W), SP. Sampling method was by contiguous permanent plots (10 x 10m), totalizing one hectare in each of three study sites within the forest (three ha in the total: Area A: site subjected to a tornado disturbance five years ago; Area B: site well conserved, with no recent anthropogenic disturbances events and, Area C: site were selective logging was registered until meddle 70’s. In each site 50 plots (10 x 10 m) were randomly assorted for the phytosociological (stems 1.30 height) and natural regeneration (1.30 < height 0.50 m, surveyed in three 1 x 10 m sub-plots within each plot) assessment. Each sub-plot established for natural regeneration survey was categorized as gap (Brokaw´s definition, 1982) or closed canopy. Microclimate was monitored four times in the year, within three consecutive days, in pairs of gap and closed canopy plots, in each of the three study sites. The preference of some tree species for regenerating in gap or closed canopy habitats was also tested. Within the three samples sites we sampled 10.570 individuals... (Complete abstract click electronic access below)