Abstract Sexual ornaments have developed in a very wide variety of animal taxa to increase fitness by improving mating success. How increased mating rate improves fitness is obvious in the case of most males: each mating provides more offspring. Whether more matings benefit females, whose fecundity is limited by resources and not mates, is unclear. Mate choice is linked to ornamentation, when individuals of one sex choose who to mate with based on the ornamentation in members of the other sex. Ornaments may work as a basis for mate choice due to conveying information about the quality of the mate. Mate choice may then lead to intrasexual competition for mates in the chosen sex as animals try to outcompete their neighbours and attract more mates. My aim in this thesis is to study the purpose and costs of female ornamentation as well as female competition for males. The main questions revolve around understanding what information female ornaments provide about the bearer and how males choose between females. I also examine how females compete against each other and what the costs of being ornamented are for a female. To study these questions I use the common glow-worm (Lampyris noctiluca Linnaeus, Lampyridae), whose females glow at night to attract flying males. According to my results, a female’s glowing provides accurate information about fecundity and males base their choice of mate on the intensity of female glowing. I showed that the perceived strength of an ornament in comparison to others close by is more important than the actual strength of an ornament. In the glow-worm, the perceived strength of an ornament depends on distance to the observer, making the system open to exploitation. A mathematical model I developed suggested that dull females could outcompete brighter ones by choosing optimal locations, and experimentation showed this to be the case. Finally, my results show that glow-worm females lose eggs each day they remain unmated. This suggests that the evolution of female ornamentation may have been driven in part by the need to find a mate as soon as possible after eclosion. Which in turn means that female and male ornamentation may have fundamentally different purposes: for females mating soon may be important, where for males the total number of offspring fertilized is critical. / Tiivistelmä Seksuaalisia ornamentteja on kehittynyt hyvin laajaan kirjoon eläinlajeja parantamaan yksilöiden kelpoisuutta nostamalla niiden parittelutodennäköisyyttä. Koirailla parittelutodennäköisyyden ja kelpoisuuden välinen yhteys on yleensä selvä: jokainen parittelu nostaa jälkeläismäärää. Naarailla yhteys ei ole yhtä selvä, sillä niillä jälkeläismäärä yleensä riippuu resurssien saatavuudesta eikä kumppanien määrästä. Parinvalinta on kiinteästi yhteydessä ornamentaatioon: Yhden sukupuolen yksilöt päättävät kenen kanssa paritella toisen sukupuolen yksilöiden ornamenttien laadun perusteella. Ornamentit toimivat valinnan perusteena välittämällä tietoa parin laadusta. Parinvalinta voi johtaa yksilöiden väliseen kilpailuun kumppaneista valitun sukupuolen sisällä. Tässä väitöskirjassa tarkoituksenani on tutkia naaraiden ornamenttien tarkoitusta ja kustannuksia sekä tutkia miten naaraat voivat kilpailla toisiaan vastaan koiraista. Pääkysymykset liittyvät ornamenttien välittämään informaatioon ja siihen miten koiraat valitsevat kumppaninsa. Lisäksi tarkastelen miten naaraat voivat kilpailla keskenään ja mitä kustannuksia ornamenteista on naaraille. Kysymysten selvittämiseksi käytän tutkimuslajina kiiltomatoa (Lampyris noctiluca Linnaeus, Lampyridae), lajia jonka naaraat loistavat öisin houkutellakseen lentäviä koiraita. Tulosteni mukaan kiiltomatonaaraan loiste välittää tarkkaa informaatiota niiden munamäärästä ja koiraat osaavat valita parinsa tämän perusteella. Osoitin, että ornamentin havaittu vahvuus verrattuna ympärillä oleviin on tärkeämpää kuin ornamentin todellinen vahvuus. Kiiltomadolla havaittu kirkkaus riippuu etäisyydestä havaitsijaan, mikä tekee signallointijärjestelmästä avoimen väärinkäytölle. Laatimani matemaattisen mallin mukaan himmeät naaraat voisivat päihittää kilpailussa kirkkaampia valitsemalla parempia loistamispaikkoja. Käytännön kokeet osoittivat tämän pitävän paikkansa. Viimeinen tulokseni oli, että kiiltomadolla naaras menettää osan munistaan joka päivä jonka se joutuu odottamaan parittelua. Tästä voi päätellä, että naaraan ornamentin evoluutiota on voinut osaltaan ajaa tarve paritella mahdollisimman pian aikuistumisen jälkeen. Naaraiden ja koiraiden ornamenttien syyt voivat olla hyvin erilaiset: naarailla parittelu mahdollisimman pian voi olla tärkeintä, kun koiraalla parittelukumppanien määrä on tärkein.

This Master’s Thesis within the area computer security concerns ”Computer viruses: The threat today and the expected future”. Firstly, the definitions of computer virus and the related threats are presented; Secondly, current situation of computer viruses are discussed, the working and spreading mechanisms of computer viruses are reviewed in details, simplistic attitude of computer world in computer virus defence is analyzed; Thirdly, today’s influencing factors for near future computer virus epidemics are explained, then it further predicts new possible types of computer viruses in the near future; Furthermore, currently available anti-virus technologies are analyzed concerning both advantages and disadvantages; Finally, new promising trends in computer virus defence are explored in details.

Mopane (Colophospermum mopane) trees are browsed upon by two key species, namely mopane caterpillars (Imbrasia belina) and African elephants (Loxodonta africana), which each inflict a different type of damage while feeding, namely defoliation (leaf removal) and pruning (branch and/or stem breakage). Damage type can have a significant influence on plant responses, and these induced changes in morphological and chemical characteristics of regrowth can influence the subsequent feeding behaviour by each species. The objective of this study was therefore partly to investigate the differential effect of defoliation by mopane caterpillars and pruning by elephants on mopane trees, and then to investigate whether these two taxonomically different species interact through their shared food resource, by looking specifically at the effect of elephant utilisation of mopane on mopane caterpillar abundance. To determine the comparative effect of each browsing type, mopane trees were subjected to simulated mopane caterpillar or elephant utilisation treatments, at various frequencies and times within the year. Regrowth characteristics were then measured on treatment and control trees, as well as on naturally utilised and unutilised trees. Reproductive investment was also recorded on naturally utilised and unutilised trees. Additionally, the impact of mopane caterpillar defoliation and elephant pruning on plant stress was investigated by measuring the level of fluctuating asymmetry (FA) in leaves. Then, to determine whether there is an interaction between elephants and mopane caterpillars, mopane caterpillar egg mass abundance in areas of high elephant impact was compared to that in areas of low elephant impact. Firstly, however, in areas without elephant damage, those tree characteristics determining host tree preference by ovipositing mopane moths were identified. From this, an understanding of how elephant utilisation may influence mopane caterpillar abundance could therefore be gained. Defoliation and pruning had a significant different effect on mopane regrowth responses. Shoot and leaf length were significantly longer on pruned trees than control trees, for both naturally utilised and simulated elephant treatment trees, while there was no difference in shoot density. Defoliation, however, resulted in shorter shoots and leaves, particularly on naturally defoliated trees, which also had leaves of a higher nutritional value (tannin:protein ratio and total polyphenolic content) than control trees. A similar increase in leaf nutritional value was recorded in areas of high elephant impact in the Kruger National Park, but not after simulated or natural elephant damage in Venetia, where natural elephant utilization was less intense. Time since damage (i.e. first versus second flush) had a significant influence on regrowth after pruning, as shoot and leaf length were significantly longer on trees flushing for the first time, while within-season timing of damage was important for defoliation, as late-season defoliation had a greater negative impact than mid-season defoliation. Late-season defoliation also had a negative effect on leaf carriage into the dry season, while pruning appeared to aid leaf retention. Reproductive investment was found to be unaffected by mopane caterpillar defoliation or elephant pruning, as mean pod density and pod mass on utilised trees was no different to unutilised trees. Defoliation also had no influence on a plant’s likelihood of flowering that same season, with flowering being determined more by tree height. Unlike pod production, however, mean leaf density was significantly reduced in the regrowth of defoliated trees, presumably due to the use of stored resources for reproduction prior to the onset of regrowth. Neither simulated nor natural defoliation by mopane caterpillars and pruning by elephants was found to affect the level of leaf FA in mopane trees, even though the degree of damage inflicted on trees was considerably higher than in studies on other species where increases in FA were observed. Mopane therefore appears to be extremely tolerant of herbivory in comparison to other species. A positive relationship between leaf nutritional value (higher protein and lower tannin and polyphenolic content) and FA was detected, but only when trees from all study areas (i.e. a wide range of environmental conditions) were considered simultaneously. Environmental conditions, rather than herbivory, therefore appear to have a greater stressing affect on mopane. In the absence of heavy elephant utilisation of mopane trees, tree size, rather than shoot length, leaf length, leaf FA or leaf nutritional value, was found to have the greatest influence on oviposition behaviour of mopane moths. Ovipositing moths showed a preference for the tall riverine habitat over the shorter woodland and scrub mopane. This preference for large trees was, however, not evident at the individual tree level, as even though egg mass number per tree was positively related to tree height, large trees were not utilised more than expected according to the available canopy volume in each size class (resource availability). Heavy elephant utilisation of mopane had a negative impact on the density of tall trees within an area, due to branch and stem breakage while feeding. Unsurprisingly then, mopane caterpillar egg mass abundance was also significantly reduced in these areas, even though the nutritional value of leaves was higher than in non-elephant impacted areas. Elephants therefore appear to have a negative effect on mopane caterpillar abundance, primarily due to their negative impact on the density of tall mopane trees. This megaherbivore and invertebrate do therefore interact through their shared food resource, mopane trees. / Thesis (PhD (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

Proteins are essential parts of living organisms that initiate and control almost all cellular processes. Despite the widely accepted belief that all functional proteins fold into stable and well-defined three-dimensional (3D) structures mandatory for protein activity, the existence of biologically functional disordered proteins has been increasingly recognized during past two decades. Proteins with inherent structural disorder, commonly known as intrinsically disordered proteins (IDPs), play many roles in a biological context. However, in contrast to their folded counterparts, they are dynamically unstructured and typically fluctuate among many conformations even while performing biological functions. In fact, it is this dynamical structural heterogeneity that that allows for IDPs to interact with other biological macromolecules in unique ways. Moreover, while a majority of proteins in eukaryotic proteomes have been found to have intrinsically disordered regions (IDR), the mechanisms by which protein disorder fives rise to biological functionality is still not well understood. Through a series of simulation studies on specific systems, this thesis probes several aspects of the emerging structure-function paradygm of IDPs, namely the mechanics, intermolecular assembly, and structural transitions occurring in these proteins. The lack of well-defined 3D structure in IDPs gives rise to distinct mechanical properties, the subject of the first study in the thesis on the elasticity of a elastomeric gluten-mimetic polypeptide with an intrinsically disordered character. This disordered polypeptide was shown to exhibit distinctively variable elastic response to a wide range of tensions, which a classical worm-like chain model failed to accurately describe, thus requiring a molecular-level analysis. IDPs frequently are frequently involved in protein-protein interactions, the focus of the second study on the propensity of an IDR, the B domain in dynamin-related protein 1 (Dpr1), to self-assemble into dimer structures while remaining disordered in all solution conditions. Despite a hypothesized auto-inhibitory role for this domain in Dpr1 that was assumed to be triggered by an disordered-to-order transition, the B domains in solution showed no tendency to form ordered structures even in the presence of order promoting osmolytes. Instead, self-association in the presence of osmolyte was found to occur by favorable intermolecular intereactions between specific region on the surface of the B-domains. Other IDPs do undergo a disorder-to-order transition in response to environmental cues, in ways that are unique disordered proteins, the focus of the last study on intermolecular ordering transitions in silk-like proteins. Factors such as protein sequence and physical tension were investigated, and results suggested that tyrosine residues in the key silk sequence motifs promote templating of beta structure from disordered precursors and that elongational stresses preferentialy stabilize antiparallel beta-sheet order. Together, these three computational studies provide insight into the nature of the structure-function mechanisms of IDPs.

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Purpose of this master´s thesis is a construction proposal of German Equatorial Mount capable to load capacity to 20kg inclusive both shaft-actuators. The solution contains design options of actuators of mount, design proposal of partial systems and parts and calcualtions. More is contain drafts of overal assembly, motor pinion and shaft.

Cílem této diplomové práce je zlepšit chování nanomanipulátoru, používaného v elektronovém mikroskopu, při vykonávaní nejmenších kroků pohybu. První částí je analýza mechanismu za účelem nalezení možných řešení problému. Dále se práce zabývá testováním řešení jako je optimalizace tuhosti předepínacích pružin mechanismu anebo změna mazání šnekového převodu mechanismu. Výsledkem práce je výběr nejvhodnějšího řešení problému na základě výsledků testů a následná modifikace nanomanipulátoru.

Introduction: Guinea worm disease (GWD) is a painful, disabling disease caused by the parasite dracunculus medinensis. The implementation of the global GWD eradication campaign resulted in a decrease of global burden of disease and several countries have been proclaimed free of the disease. Though, Ethiopia has implemented the GWD eradication programme since 1992 the disease remains endemic in the Gambella region. Purpose of the study: The purpose of this study was to explore the perceptions and experiences of the community of Gambella region on Guinea worm disease (GWD) eradication interventions. Methodology: A qualitative study paradigm with a phenomenological research design was employed to collect data using focus group discussions, in-depth individual interviews, document reviews, and observations. The study participants were determined by purposive sampling. Qualitative data analysis involved transcription, data entry, and management of verbal information followed by coding, categorizing into themes. Interpretation of the data was done using triangulation methodology with appropriate mechanisms for validity and trustworthiness. Result: The study found that there are gaps in the perceptions and understanding of the community and programme implementers about the achievement and application of the various interventions on the eradication of Guinea worm disease. Health education programme was not fine-tuned to the eradication of GWD by community participation. Community perception was not at the required level for the eradication of GWD due to the low success of the educational intervention. Conclusion: continuous health education targeting the community with clear objectives of helping to eradicate GWD was found to be limited in its coverage. In addition, provision of water filters necessary for GWD eradication was inadequate. Moreover, the community did not have clear understanding of the causes of GWD and its eradication strategy. It is hoped that the findings of this study would contribute significantly to the GWEP in Gambella region, as well as elsewhere where GWD may be endemic / Health Studies / M.A. (Public Health)

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