• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 7
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 32
  • 6
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Parasitological studies : post-embryonic development in the polycercus of Paricterotaenia paradoxa (Rudolphi, 1802) in Allolobophora terrestris (Savigny, 1826)

Scott, James Stuart January 1963 (has links)
1. Metchnikov's discovery of Polycerus lubrici in the Earthworm, made in 1867, is confirmed for the first time. 2. The conclusion of Joyeux and Baer that Polycercus lumbrici is the larval form of Paricterotaenia paradoxa (= Amoebotaenia lumbrici) is confirmed. 3. The intermediate host is identified as Allolobophora terrestris and the principal final host as the Woodcock (Scolopax rusticola). 4. The polycercus has been found only in immature specimens of A. terrestris. The implications of this are discussed. 5. Earthworms were experimentally infested with Polycercus lumbrici by feeding them with mature proglottides of Paricterotaenia Paradoxa from the Woodcock. 6. The incidence and habits of the Woodcock are discussed. 7. The degree and site of infestation of Paricterotaenia paradoxa in the Woodcock are discussed. 8. The development of Polycerous lumbrici in the Earthworm, from the earliest form of the larva to the cysticercoid, is described in detail for the first time. 9. MetchniRov's outline of the development of Polvcercus lumbrici is amended to include a retroversion of the larva prior to the differentiation of the primordia of the scolex, retention of the side-walls of the larva and the appearance of an axial column of cells. His account is also extended to give, for the first time, a complete description of the development of the scolex. The rostellum is formed, as in Cysticercus fasciolars, from a bulb and prebulb, the former supplying the hook-elevator muscles and the glandular elements, the latter the muscles of the walls of the rostellum and the hook-retractor muscles. The remainder of the muscles of the scolex are modifications of the parenchymal and peripheral musculature. 10. The muscular, excretory, nervous and glandular systems are described and discussed. 11. A description is given of experiments to determine: (i) suitable media for keeping the larvae alive in vitro; (ii) agents for freeing the cysticercoids from the cyst; (iii) agents which induce evagination of the scolex; (iv) suitable media for culture and development of the evaginated tapeworms. The results of the experiments indicate that: (i) the larvae can be kept alive for periods of up to five days in simple physiological solutions such as Locke's (ii) the larvae are freed from the cyst in the gizzard of the final host by a purely mechanical process; (iii) the larvae are induced to evaginate in the final host by the action of gastric juice followed by pancreatic juice, the effective agents being pepsin in the first and pancreatin in the second, (iv) the tapeworm will not develop to maturity in any of the media used. 12. The discovery of a second polycercus, the larval form of Paricterotaenla burti Sandeman, 1959 is recorded from the Earthworm Allolophora terrestris. 13. Hook development in Paricterotaenia burti is described it follows the same general pattern as that of P. paradoxa. 14. An unidentified species of Amoebotaenia is described. 15. Evidence is offered which elucidates the life-cycles of the following cestodes: (i) Paricterotaenia paradoxa: intermediate host, the Earthworm Allolobophora terrestris; final host, the Woodcock (Scolopax rusticola). (ii) Parieterotaenia burti; intermediate host, the Earthworm Allolobophora terrestris; final host, the Woodcock (Scolopax rustlcola). (iii) Paricterotaenia stelliferai: final host, various charadrriform birds; intermediate host, Tubifex. Cysticercus pachycanthus is identified as the larval form of Valipora skrjabini a parasite of the Common Snipe (Gallinago gallinago). An unrecorded cyrsticercoid from Tubifox is noted.
2

Theoretical investigations on some biological systems

Scano, Paola January 1997 (has links)
In this thesis molecular properties of different biological systems are studied by means of Quantum Mechanical methods. After a brief introduction, the basic theory of the methods here used is presented in Chapter 1. In Chapter 2 the heats of formation and the ionization potentials of some carcinogenic compounds such as Polycyclic Aromatic Hydrocarbons are studied and compared with experimental data. The methods used are the semiempirical methods with the AM1 and PM3 Hamiltonians. The results show that the experimental heats of formation are better reproduced by PM3, while as far as the ionization potentials are concerned AM1 is slightly better than PM3. In Chapter 3, the Lipid Peroxidation mechanism has been studied at the molecular level. The energetic details of the pathway proposed by Porter have been studied using the semiempirical AM1 and PM3 Hamiltonians. Six model compounds, which retain the same functional characteristics as the physiological fatty acid, have been used. The results are in good agreement with the experimental observations. Characteristics and metabolism of the anticancer drug NMF (N-Methylformide) have been studied in detail in Chapter 4. Accurate ab initio calculations have been carried out and the effect of the solvent has been taken into account. The results represent a good example of the high quality of information that the application of ab initio methods can give when properties of molecules and energetic details of pathways are examined.
3

Studies on s-allele incompatibility in Brassica oleracea

Sedgley, Margaret January 1974 (has links)
By the end of 1972, a total of thirteen rabbits had been injected. One serum was raised to Brassica oleracea S23S23 kale pollen proteins, but no s-antibody was stimulated. All the others were raised to stigma proteins. A range of s-alleles and varieties of B.oleracea was used including S23S23, S16S16 kale, S2S2, S45S45 and S5S5 brussels sprout and S15S15 cabbage. S15 and S5 were of low dominance, S2 and S45 of intermediate dominance and S23, S14 and S16 of high dominance. S-antibodies were raised to S23 and S16 in kale, and S2 and S45 in brussels sprout. Only the S16-antibody had a high titre of 1/16, the other were 1/4 or less. In two of the cases , booster injections stimulated the S-antibody response where the first course of injections stimulated the S-antibody response where the first course of injections stimulated the S-antibody response where the first course of injections had failed. Relatively dilute stigma extracts of 250 stigmas/ml stimulated most s-antibodies. An injection schedule of more than two months produced cross-reactions or new specificities. Extract which had been frozen or treated with formalin gave a poorer antibody response than freshly-prepared extract. No S-antibodies were stimulated by these treatments. In its present form, the technique was unsuitable for routine S-allele diagnosis in B.oleracea because of the low rate of successful sera and the low titres stimulated. Improvements to the technique are suggested. Between 35 and 40% of the total protein content was lost when a stigma extract was frozen, but the S-protein was not lost. B.oleracea pollen germinated on an agar and sucrose medium. Germination was stimulated by 0.0005% queroetin, but tube growth was not. Querotin was detected as glycosides in the pollen and stigma tissue of B.oleracea. It was not involved in the incompatibility reaction of the stigma.
4

Ion dynamics in collisionless shock waves

Sherwell, David January 1976 (has links)
In a laminar model of a collisionless magnetosonic shock wave, ion equations of motion are integrated through shock-like profiles. Conservation relations and Maxwell's equations allow a self-consistent determination of unknown downstream ion distribution functions fᵢ, ion temperature Tᵢ, and electric potential jump ̧›ʺ. Favourable comparison of model Tᵢ, ̧›ʺ. Favourable comparison of model Tᵢ, ̧›ʺ , with experiment establishes (at low ̧›ư ́œø O.3, ̧›ư=8 Ï€ N [sub] l k (T[sub]é‚‚+Tᵢ[sub]l)/B́‚℗ø) importance of laminar ion dynamics. Heating is due to distortion of Maxwellian distributions when entropy is conserved; in particular shock dynamics is dominated by a fast "tail" of reflected ions. The solutions for fᵢ are considered. The "stability" of the model to its assumptions (linear profiles, shock thickness (L[sub]s)) is shown. When reflections occur a self-consistent length emerges. The solutions Tᵢ, ̧›ʺ are extensively studied at various Mach numbers for different values of ̧›ư. Laminar ion heating is very efficient and at high ̧›ư can exceed proper conservation levels due to ion reflections; at high ̧›ư(́œÆ ̧›ư *) the electric potential is unable to slow the ions to conservation levels. The model predicts significant reflected ion currents in the plane of the shock. The boundary ̧›ư * is determined. Then laminar ion dynamics on the scale of the electron heating length (~10 C/w[sub]p ́‚‘) cannot occur for ̧›ư > ̧›ư *. Dependence on L[sub]s and T ́‚‘́‚,/Tᵢ́‚ is considered. The nature of non-laminar ̧›ư >̧›ư* shocks is considered. Collisions are found to be important in laboratory shocks, and are efficient in slowing the reflected ions. In the absence of collisions, ion instabilities must be considered. It is shown that turbulent slowing of the fast ions cannot take place in L[sub]s alone. Further it is shown possible to construct a shock so that non-laminar mechanisms cannot occur significantly. Then the laminar model is re-instated. A decoupling of ion and electron heating lengths is proposed. Reflection heating in the Earth's Bow Shock (̧›ư>̧›ư*) is modelled, and is comparable with experiment.
5

Inverse polarity prominence equilibria

Scho¨nfelder, Apollonia Maria Oktavia January 1995 (has links)
It has been supposed since the middle of this century that it is the global magnetic field surrounding a quiescent prominence that provides the force to prevent its collapse due to the sun's gravitational field. Many theoretical models, assuming that the prominence plasma is supported in a dip in the magnetic field lines associated by the magnetic tension force, have since been put forward. The aim of this thesis is to propose further models of quiescent prominences to widen our understanding and knowledge of these remarkable features. A short overview over the magnetohydrodynamic equations used to describe solar prominences, or most of the solar phenomena for that matter, are discussed in chapter 2, and a short summary of prominence observations and attempts to model them is given in chapter 3. A brief description of the numerical code used in chapters 5 and 7 is given in chapter 4. Observations of Kim (1990) and Leroy (1985) have found that most large quiescent prominences are of inverse polarity type for which the magnetic field passes through the prominence in the opposite direction to that expected from the photospheric magnetic field. Many theoretical models have been proposed, but failed. Hence, in chapter 5 we investigate first – without the inclusion of a prominence sheet – when an inverse polarity magnetic field must have the correct topology for an inverse polarity configuration before the formation of the prominence itself. Only very recently, the first basic successful model of an I-type polarity prominence was proposed by Low (1993). In chapter 6 we examine this model and investigate current sheets more complicated and realistic than the one used by Low. These analytical models deal with the force-free solution, which is matched onto an external, unsheared, potential coronal magnetic field. These solutions are mathematically interesting and allow an investigation of different profiles of the current intensity of the magnetic field vector and of the mass density in the sheet. The prominence properties predicted by these models have been examined and have been found to match the observational values. The mathematics of current sheets in general is also briefly discussed. Chapter 7 deals with numerical solutions of inverse polarity prominences embedded in a force-free magnetic flux tube, matched onto an unsheared potential coronal field. Unfortunately the solutions gained are quite sensitive to the boundary conditions imposed on them through the numerical box, showing a loss of convergence and a tendency for the solution to blow up. Finally, a short summary as well as possible future work is given in chapter 8.
6

Technofetishism of posthuman bodies : representations of cyborgs, ghosts, and monsters in contemporary Japanese science fiction film and animation

Lan, Kuo-Wei January 2012 (has links)
The thesis uses a feminist approach to explore the representation of the cyborg in Japanese film and animation in relation to gender, the body, and national identity. Whereas the figure of the cyborg is predominantly pervasive in cinematic science fiction, the Japanese popular imagination of cyborgs not only crosses cinematic genre boundaries between monster, disaster, horror, science fiction, and fantasy but also crosses over to the medium of animation. In regard to the academic research on Japanese cinema and animation, there is a serious gap in articulating concepts such as live-action film, animation, gender, and the cyborg. This thesis, therefore, intends to fill the gap by investigating the gendered cyborg through a feminist lens to understand the interplay between gender, the body and the cyborg within historical-social contexts. Consequently, the questions proposed below are the starting point to reassess the relationship between Japanese cinema, animation, and the cyborg. How has Japanese popular culture been obsessed with the figure of the cyborg? What is the relationship between Japanese live-action film and Japanese animation in terms of the popular imagination of the cyborg? In particular, how might we discuss the representation of the cyborg in relation to the concept of national identity and the associated ideology of “Japaneseness”, within the framework of Donna Haraway's influential cyborg theory and feminist theory? The questions are addressed in the four sections of the thesis to explore the representation of the gendered cyborg. First, I outline the concept of the cyborg as it has been developed in relation to notions of gender and the ‘cyborg' in Western theory. Secondly, I explore the issues in theorising the science fiction genre in Japanese cinema and animation and then address the problem of defining science fiction in relation to the phenomenon of the cyborg's genre-crossing. Finally, I provide a contextualising discussion of gender politics and gender roles in Japan in order to justify my use of Western feminist theory as well as discuss the strengths and limitations of such an approach before moving, in the remainder of the thesis, to an examination of a number of case studies drawn from Japanese cinema and animation.
7

Examples of Volume-Preserving Great Circle Flows of S3

Haskett, Ryan 01 May 2000 (has links)
This summer Herman Gluck and Weiqing Gu proved the last step in a process that took conformal maps between two complex spaces and related them to Volume Preserving Great Circle Fibrations of S3. These fibrations, which are non-intersecting flows, break down under certain conditions. We obtained the fibrations by applying the process to different conformal maps then calculated the angles where they intersect. This paper centers around the developments in the method for converting the conformal maps and finding the critical angles. Finally, the examples are included in their various stages of completeness.
8

Synchronizing permutation groups and graph endomorphisms

Schaefer, Artur January 2016 (has links)
The current thesis is focused on synchronizing permutation groups and on graph endo- morphisms. Applying the implicit classification of rank 3 groups, we provide a bound on synchronizing ranks of rank 3 groups, at first. Then, we determine the singular graph endomorphisms of the Hamming graph and related graphs, count Latin hypercuboids of class r, establish their relation to mixed MDS codes, investigate G-decompositions of (non)-synchronizing semigroups, and analyse the kernel graph construction used in the theorem of Cameron and Kazanidis which identifies non-synchronizing transformations with graph endomorphisms [20]. The contribution lies in the following points: 1. A bound on synchronizing ranks of groups of permutation rank 3 is given, and a complete list of small non-synchronizing groups of permutation rank 3 is provided (see Chapter 3). 2. The singular endomorphisms of the Hamming graph and some related graphs are characterised (see Chapter 5). 3. A theorem on the extension of partial Latin hypercuboids is given, Latin hyper- cuboids for small values are counted, and their correspondence to mixed MDS codes is unveiled (see Chapter 6). 4. The research on normalizing groups from [3] is extended to semigroups of the form < G, T >, and decomposition properties of non-synchronizing semigroups are described which are then applied to semigroups induced by combinatorial tiling problems (see Chapter 7). 5. At last, it is shown that all rank 3 graphs admitting singular endomorphisms are hulls and it is conjectured that a hull on n vertices has minimal generating set of at most n generators (see Chapter 8).
9

Výběr informačního systému / Information System Selection

Zmija, Tomáš January 2014 (has links)
This master's thesis deals with analysis and selection of a new information system for a small company Výtahy – Elektro Žižka, s.r.o., which is engaged in manufacturing, reconstructing, and with revision of elevators. The main goal of the thesis is to analyse current condition of company’s hardware and software equipment and eventually suggest some possible improvements. Furthermore the thesis deals with main business processes according to which the information system will be chosen. Based on these changes, the time and financial plan will be formed.
10

An Examination of the Carbonaceous Materials in the S3 Bed of the Barberton Greenstone Belt, South Africa

Scroggs, Elizabeth E. January 2011 (has links)
Carbonaceous materials found in Archean rocks have been the source of study and controversy for the last two decades due to questions of the biogenecity of these particles. One of the key locations for these studies is the Barberton Greenstone Belt (BGB), in South Africa which contains some of the oldest known rocks on Earth, ranging in age from 3.5 to 3.2 billion years old. Preserved within the Onverwacht and Fig Tree Groups of the BGB are spherules that formed by the condensation of an impact-produced global vapor plume. The spherules are distal deposits that would have been deposited globally, but are only preserved at this location and in western parts of Australia. Like several other sediments in the BGB, there is evidence of minor amounts of carbonaceous particles contained within the spherule beds. Four individual impact events are preserved in distinct beds designated as S1, S2, S3, and S4. Due to the wide distribution of this bed in a variety of depositional settings, including both protected shallow and deep water depositional settings where there is little evidence of reworking, the S3 bed is an ideal choice for mineralogical, geochemical, and petrographic studies of impact spherules. This research examines samples from four different locations of the S3 spherule bed layer, the Barite Syncline, Maid-of-the-Mist, Sheba Mine, and Loop Road locations, in order to determine the origin of carbonaceous particles contained within the bed. Several geologic processes could account for the presence of the carbonaceous materials within the S3 spherule bed layer. These processes include: (1) Diagenetic processes, (2) Fisher-Tropsch Synthesis, (3) Microbial activity, and (4) Primary condensates from the impact plume. In order to distinguish between these processes, the spatial distribution of the carbonaceous matter was mapped, noting the mineral associations with these grains. Petrographic and electron microanalytical studies of the S3 samples reveal the presence of carbonaceous material in the sections with highly concentrated spherules, Barite Syncline, Loop Road, and Sheba Mine locations, but not in the samples from the Maid-of-the-Mist location, where there is a low concentration of spherules and abundant admixed volcanic detritus. Only Fischer-Tropsch Synthesis can be excluded as a process responsible for the origin of carbonaceous materials in the S3 beds. Though there is no direct evidence of the biogenecity of the observed carbonaceous materials, other textual observations within the S3 spherule bed are consistent with microbial activity, including Ambient Inclusion Trails and an unusual feature with a cyanobacteria-like morphology. While microbial activity cannot be ruled out as a process responsible for the origins of the carbonaceous materials, the findings of this study indicate that the carbon was mobilized from within the spherules during diagenesis. The location of carbon along spherule rims and microfractures within the spherules can also be attributed to diagenetic processes, such as fracture flow, dissolution, and replacement. A plausible explanation is that the carbon was a primary condensate from the impact plume, but has been diagenetically remobilized locally into microfractures and along the rims of the spherules. / Geology

Page generated in 0.0177 seconds