VictorJuiz/thesis huggingface dataset:
Interactions of waves and particles in plasmas with reference to an experimental study of current-driven turbulence

This thesis is an experimental study of a plasma which is made strongly turbulent by conducting an electric current. The experiments are performed on the cylindrical potassium plasma column which exists between the hot and cold end-plates of a single-ended Q-machine. The plasma is continuously produced at the hotplate by contact ionization and confined radially by a strong axial magnetic field such that ωce » ωpe. The electrons and ions are initially close to thermal equilibrium with the hotplate, with a common temperature ≃ 0.2eV. The plasma density (~ 109 cm-3), is such that the time for collisions between electrons and ions is very long compared to the time taken for an electron to travel the length of the column.
Pulsed electron currents of duration ~ 2 μs are drawn through the plasma by applying positive voltage pulses (≲ 100V) to the cold plate. Simple electrical measurements indicate that, above a critical current, the plasma has an anomalously low conductivity accompanied by the onset of a high level of potential fluctuations, which are detected in the plasma by electrostatic probes.
A diagnostic technique has been developed to study the temporal evolution of the distribution function of axial electron velocities. This involves time-resolved measurements of the dispersion of electron plasma waves during the current pulse. Analysis of this dispersion gives unambiguous measurements of the electron density n, drift velocity vd, and root mean square (or thermal) velocity ve, during the pulse. The results indicate that, after an. initial transient, n and vd are axially uniform, n remains equal to the initial value and the current drawn from the plasma gives a good measure of their product. The critical current corresponds to vd = 1.3 vc, which linear theory predicts, is the threshold for the electron-ion two-stream instability. Above this threshold, ve quickly exceeds vd and, in contrast to the predictions of linear theory and computer simulation, continues to rise for constant vd to high values, (indicating electron temperatures ≲ 80 eV), limited only by the energy containment time of the column. The values of conductivity deduced from the effective scattering rate and from the electrical measurements are in good agreement, and are consistent with an empirical scaling law found in a pulsed toroidal discharge by other workers.
Measurements on the potential fluctuations indicate a broad frequency spectrum: in the low frequencies the correlation lengths were too short to be measured; in the high frequencies the fluctuations were shown to consist of relatively coherent, long wavelength electron plasma waves.
Addition reactions of unsaturated compounds with some heterocyclic systems, and further reactions of their products

The Introduciton surveys the results obtained since a 1962 review from investigations of the reactions of heterocyclic compounds and acetylenic esters.The chemistry of the cycl [3,2,2] azine system [1] first described in 1958 is discussed and particular mention is made of the syntheses of derivates of compound [1] from indolizine [2] and acetylenic esters. [to continue reading the abstract please see the pdf]
Aspects of steady and pulsatile flow in branched tubes with particular reference to blood flow

The nature of the flow in branching blood vessels is of importance to physiologists, mainly on account of the formation of atheromatic deposits which occur frequently at sites of branching. The reasons for the occurrence of these deposits are not yet understood but it is generally agreed that the effects of fluid dynamics may well be important. There is, however, a lack of knowledge as to the detailed nature of the flow at and around branches and this study has been undertaken in order to provide such knowledge.
The flow in symmetrical branches, typical of the blood vessels in man, has been studied using rigid-walled models perfused with steady and pulsatile water flows. The streamline patterns have been studied using dye and hydrogen bubble tracers and the effects of pressure differences and obstructions have also been investigated. Detailed measurements of axial velocity distribution and wall shear stress have been made with heated element probes developed for these applications. The design of these probes and the development of a digital output system are described.
The following observations and conclusions have been made:
1. Contra-rotating, helical vortices are set up on the outside of each limb, their strength varying with the mean square of the input velocity. These vortices spread across the whole of the tube to give an approximately symmetrical velocity distribution within about six diameters downstream, this distance being independent of input velocity and profile.
2. There is markedly high shear stress on the inside wall of each limb and low shear stress on the outside wall. This differential is only maintained significantly, however, for 4 or 5 diameters downstream.
3. The mass flow distribution between the two limbs of a branch is very sensitive to small pressure differences between the limbs. This is not a flow switching (Coanda) effect, but a consequence of the relatively small pressure drop in each limb, Obstructions near the apex of the branch do not in general affect the mass flow distribution.
4. The stability of the downstream flow development depends on the input velocity, the stability increasing with decrease of velocity.
5. The interior geometry of the branch has only minimal effect on any downstream measurements.
6. The downstream flow patterns and velocity distributions in pulsatile flow show that there is little difference between the downstream effects in pulsatile and steady flow and that most pulsatile flows can be considered quasi-steady. Pulsatile flow tends to stabilise the downstream flow development.
7. Preliminary observations in a confluence show that there is no high shear stress at any position. In steady flow, vortices are shed from the apex causing pulse-shaped velocity and shear stress variations downstream. The frequency of the vortex shedding increases linearly with velocity.
Cognitive bias modification in the context of depression: interpretation bias and mental imagery

The aim of this thesis was to develop a positive Cognitive Bias Modification (CBM) technique using imagery in the context of depressed mood. CBM targets biases associated with emotional disorders. CBM modifying interpretation bias (CBM-I) has been investigated for anxiety, but not depression. Whilst many cognitive processes contribute to depression, the current focus was on mental imagery and interpretation bias. In a series of six studies a positive, imagery-oriented CBM-I was developed, culminating in a final test in a clinically depressed population.
Prior research had demonstrated that for positive CBM-I, a verbal rather than imagery condition was not only less effective at promoting positive mood, but led to mood deterioration. Experiment 1 investigated what aspect of verbal processing might be responsible for the paradoxical increase in negative emotion. Results suggested that unfavourable comparisons between the self and the positive CBM-I material was driving the increased negativity. Experiment 2 investigated whether making such comparisons in an imagery mode would yield similar effects and whether field perspective imagery instructions would enhance positive CBM-I. Results indicated that optimal instructions for CBM-I should include field perspective imagery whilst discouraging comparative processing.
Studies 3a and 3b investigated the relationship between interpretation bias, mental imagery and depressive symptoms in a large sample. Interpretation bias discriminated between low and high dysphoric participants, who had a greater frequency of negative intrusive images. To target negative intrusive images, a new CBM-I technique was developed in Study 4 and Experiment 5 - "CBM of appraisals". Compared to negative CBM of appraisals training, positive training led to fewer intrusive memories and less intrusive symptomatology concerning a depressive film after one week.
Finally in Experiment 6, a multi-component CBM-I package (including auditory CBM-I from Experiments 1 and 2; CBM of appraisals from Study 4 and Experiment 5; plus a picture-word technique) was tested in 24 participants with clinical depression. Positive compared to neutral multi-component CBM-I led to improvements in interpretation bias, appraisal bias, depressive and intrusive symptoms. This suggests the potential clinical benefit of a multi-component positive imagery-oriented CBM-I package.
Some applications of the theory of group representations in mathematical physics

This thesis is concerned mainly with the accidental degeneracy of the n-dimensional anisotropic harmonic oscillator.
The general concept of accidental degeneracy is defined, and a summary is given of some of the explanations for it.
A description is presented of Mackey's theory of group representations for general semi-direct product groups. This is followed by a method for the explicit application of the theory to the cases which arise in this thesis.
A group G associated with the n-dimensional anisotropic harmonic oscillator is constructed : G is essentially a group generated by the position and momentum observables, the identity operator and the Hamiltonian of the system. All the quantum mechanical irreducible representations of G are evaluated (up to unitary equivalence), using Mackey's theory.
G is shown to be embedded in the semi-direct product L of the Weyl group N (generated by the position and momentum observables and the identity operator) and the symplectic group Sp(2n, ℝ). It is then proved that the degeneracies of the energy levels of the n-dimensional anisotropic harmonic oscillator with frequencies (ω1,ω2...,ωn) occur in the following way. A particular induced representation Rv of the group L, when-restricted to G, is unitarily equivalent to:
⊕s dω,sUvG,,-(sgn v)s
when v ≠ 0, where dω,s is precisely the degeneracy of the energy level Eω,s of the system, UvG,-(sgn v)s is an irreducible representation of G, and the summation may be regarded as over all distinct energy levels Eω,s of the system.
The remainder of the thesis is devoted mostly to a study of the representation Rv of L.
Because the subgroups U(n) and SU(n) of L may be taken as degeneracy groups of the n-dimensional isotropic harmonic oscillator, the decompositions of the restrictions of Rv to U(n) and SU(n) are examined.
All the quantum mechanical irreducible representations of the subgroup NSU(n) of L are found (up to unitary equivalence), using Mackey's theory. It is then shown that NSU(n) is a non-invariance group for the n-dimensional isotropic harmonic oscillator, with a representation UvN WSU(n)u (v ≠ 0) as the appropriate irreducible representation of NSU(n). Moreover, UvN is the restriction to N of the representation UvG),-(sgn v)s
The representation Rv (v ≠ 0) of L is proved to be unitarily equivalent to an inner Kronecker product representation of L : UvN WSp(2n, ℝ)⊗W(2n, ℝ), where UvN WSp(2n, ℝ) is an irreducible projective representation of L, and WSp(2n, ℝ)⊗W(2n, ℝ) is the complex conjugate of the protective representation WSp(2n, ℝ) of Sp(2n, ℝ). Furthermore, the restriction of UvN WSp(2n, ℝ) to NSU(n) is the irreducible representation UvN WSu(n) of NSU(n), which arises in proving that NSU(n) is a non-invariance group in the isotropic case.
Finally, it is shown that Rv (v ≠ 0) splits into two irreducible representations of L.
The biochemical properties of drug-resistant mutants of bacteria and other micro-organisms

An investigation has been made of the biochemical mechanisms of resistance to sulphonamide drugs in five strains of staphylococci. Resistant strains of micro-organisms for comparative studies are usually derived from sensitive parent organisms by a number of procedures, of which the most frequently used is repeated subcoltivation in the presence of increasing concentrations of inhibitor.
There are several possible mechanisms of drug-resistance, and some of these have been demonstrated in sulphonamide-resistant organisms. More is known about the mode of action of the sulphonamides than of most antibacterial substances, and this information directs attention to the metabolism of p-aminobenzoic acid (PAB) and folic acid, where changes seem likely to lead to the development of resistance.
[To continue reading the abstract please see the pdf]
Father’s role in infancy: examining the influence of paternal depression in the postnatal period on early father-infant interactions

Background: Parental depression in the post-natal period is associated with an increased risk of adverse child outcomes. Research has consistently revealed impaired interactions of postnatally depressed mothers, and this is one pathway by which children are affected. Evidence suggests that depression can also affect fathers in the postnatal period and this influences children's development; yet we are only beginning to understand the factors that explain this intergenerational transmission. This thesis aims to examine: (i) the influence of paternal depression on father-infant interactions at three months and (ii) the potential mediating role of these early interactions in the development of later child externalizing problems.
Method: In a longitudinal investigation, 118 fathers were assessed for depressive symptoms postnatally using a structured clinical interview. Observational behaviours of fathers and their infants were coded using the Global Rating Scale (GRS). Two exploratory studies were conducted on a sub-sample of depressed and non-depressed fathers, matched on age and education (n=38). In the first study, behaviours representing the paternal repertoire were measured and in the second, paternal speech was analysed. New scales were developed for both these studies. Child Externalizing behaviours at one year were measured using maternal ratings on the Child Behaviour Checklist (CBCL/1½-5).
Results:Depressed fathers were more withdrawn in their interactions with their infants and more negative in their speech compared to controls. They engaged in less gentle touch, fewer episodes of excitatory arousal and less active engagement. Decreased engagement mediated the association between paternal depression and child behaviour problems.
ConclusionThis study has identified aspects of father-infant interaction that are impaired by depression. These parenting behaviours may be a potential target of intervention in postnatally depressed fathers.
Studies of rotational isomerism

Because the measured thermodynamic properties of ethane did not agree with those calculated from statistical mechanics, Pitzer proposed the existence of energy barriers hindering internal rotation about single bonds. A consequence of hindered rotation is that molecules may exist in more than one stable conformation: these conformations are referred to as "rotational isomers". Depending on the magnitude of the energy barrier relative to thermal energy, the conformers (or rotamers) may be individually isolable (as in ortho-substituted biphenyls) or in dynamic equilibrium (as in halogeno-ethanes). There is no simple explanation for the magnitudes of energy barriers: the various theories which have been proposed are reviewed by Dale and Lowe.
Irrespective of the barrier height, the infra red spectrum of a mixture of two rotamers often shows doubling of characteristic group bands. Thus chloroacetone (I), in carbon tetrachloride solution, has two carbonyl bands which may be assigned to rotamers (la) and (Ib).
[Please see pdf. for full abstract.]
The isolation and characterization of orbiviruses from ticks (ixodes uriae)

Ticks (Ixodes (Ceratixodes) uriae] were collected from two seabird colonies on the Isle of May in Scotland. Viruses were isolated from three tick pools, one from ticks collected during 1979 and two from ticks collected during 1981. The viruses replicated in suckling mouse brain, chick embryo fibroblasts, Vero and BHK-21 cells, but not in Xenopus cells. By virtue of their morphology in infected cells, physicochemical properties and reactions in complement fixation tests, they were identified as Kemerovo serogroup viruses belonging to the Great Island Complex (Orbivirus:Reoviridae). Ihe three isolates were distinguished from each other by plaque reduction neutralization tests. After three cycles of plaque purification, the replication of one isolate, Mill Door/79 virus, was examined in Vero and BHK-21 cells. The virus grew to maximum titres 8 to 9 hours post infection (p.i.); over 99% of the infectivity was cell-associated. Twelve virus-specified polypeptides, p141, p93, p69, p65, p53/51, p44, p37, p36, p30, p27, p21 and p20 were identified in infected Vero cell lysates by polyacrylamide gel electrophoresis (PAGE). Similar polypeptide profiles were observed in infected BHK-21 cell lysates. Attempts to purify the virus, by polyethylene glycol-6000 precipitation, resulted in the detection of p93, p69, p53/51, p37, p21 and p20 after PAGE, whereas only four, p93, p69, p53/51 and p37 were detected after attempts at purification using ether extractions. Results using pr~ase inhibitors and partial proteolysis indicated that three virus-specified polypeptides (p36, p30 and p27) may be cleavage products. All virus-specified polypeptides, with the exception of p30 and p20, were labelled in infected cell cultures with both [14c] mannose and [14c] glucosamine. [To continue reading the abstract please see the pdf]
Aerodynamics of high performance turbine blading

A major addition to European research facilities is the Oxford University Engineering Laboratory (O.U.E.L.) blowdown tunnel which can provide full-scale Reynolds and Mach number simulations on large and small models of turbine stage components. The facility was designed to provide extended aerodynamic capabilities to complement the existing heat transfer research in the Isentropic Light Piston Tunnel (ILPT) at O.U.E.L. The blowdown tunnel will be used for fundamental investigations of the boundary layers and flow fields around turbine blades in a linear cascade. The study of these flow fields is necessary for the prediction of heat transfer rates and for the optimisation of materials and cooling schemes required to improve gas turbine efficiencies.
As a commissioning exercise measurements were made on cascades of similar geometry to those which had been previously tested in the ILPT and in other European facilities in order to compare results and analyse differences which occur due to the influence of tunnel geometry. Measurements made on various rotor profiles identified regions on the suction surface where surface pressure data is sensitive to the various types of exit plenums and exit pressure gradients.
A second phase of work included measurements and a theoretical study of the boundary layer on a large-chord turbine rotor profile. Measurements on the pressure surface of the blade suggested the presence of secondary longitudinal vortices which rapidly lose an identifiable structure towards the trailing edge. On the suction surface, boundary layer measurements were compared with theoretical models, and it was shown that current numerical models of compressible turbulent boundary layers approximately correspond with the data. An adjunct to the boundary layer work was research on the use of a hot-wire anemometer, intended for future boundary layer measurements, and for which calibration laws and temperature effects were studied.
George Rliot and the religion of humanity

Auguste Comte and George Eliot were both typical of their time but this thesis contend& that many of the elements of his system found expression in her novels. It contains three parts: a study of Comte's ideas, a short history of their propagation in England, and an analysis of Eliot's novels. An appendix examines the previous critica1 recognition of her Positivism.
In Part One, a brief consideration of Comte's life and philosophical context leads to a thematic treatment of his ideas; in philosophy his development from the positive to the subjective method and his modified determinism, in history and sociology his law of the three states and his political utopia. in ethics his cerebral theory, and in religion his worship of women. A final chapter illustrates George Eliot's close study of Comte.
Part Two traces the reception of Comte's ideas in England, from the eariy enthusiasm of Mill and Lewes to the more orthodox discipleship of the Wadham Positivists. George Eliot's position in the whole spectrum of Positive thought is assessed in relation to these writers and to the widespread discussion of Comte in mid-Victorian England.
Part Three passes from George Eliot's religious development prior to her reading of Comte to her discussion of Positivism in her notebooks, essays and letters. Her novels are considered under the same thematic divisions as Comte's ideas. Her philosophy sought the same subjective synthesis of Positive knowledge and taught Comte's balance of resignation and activity. Positive elements are detected in her treatment of solidarity in Felix Holt, utopianism in Middlemarch, history in Romola, and continuity in Daniel Deronda. Her ethics revolved around a Comtean development of altruism through the famiiy and the worship of women. The extent to which she accepted or modified Comte's Religion of Humanity is the subject of the final chapter.
The missionary outreach of the west Indian church to west Africa in the nineteenth century with particular reference to the baptists

The study of history is the interpretation of events in their relationships at a particular time. This is a subjective exercise with some degree of objectivity and this thesis is no exception. It is a study by a Jamaican Baptist minister who has always been a Baptist, examining the changing relationships of four events which find a focus in one of them - a mission of the Jamaican Baptist Church to Africa in 1843.
Firstly, this is a study of the development of a 'church consciousness' among the Baptists in the island between 1783 ana 1843, for without this a mission would have been impossible. There has been an investigation of the church structure and programme in an attempt to discover whether there existed a relationship between their ethnic composition and an African mission. Simultaneously, there has been an assessment of the importance of 'Africa' as an ideal both for the Anti-Slavery Movement and for the freed-slave in the churches.
Secondly, this is a study of rivalry between 1.·:is sionary Societies in the local situation. There has been an examination of the changing relationships between the B.M.S and both the Jamaica and African missions, especially after 1843. This assessment has proved a useful model with which to examine the tensions which are likely to occur between a missionfield and missionary-agency. With this in mina, the Eissionary Societies have been examined as regards the events of 1842 and the independence of the Jamaican Baptist churches.
Thirdly, this is a study of the settlement and penetration of Fernando Po (Santa Isabel) and the adjacent mainland by the Baptists between 1841 and 1853, with an emphasis upon the life and work of the Jamaica-related missionaries.
Fourthly, this is a study of the changing policy of the B.M.S. to Blacks. It examines the place of 'Race' or the interpretations of 'Race' in the outworking of Committee decisions and assesses its influence upon financial policy and ecclesiological definitions of the mission church.
[To continue reading the abstract please see the pdf]