Ocular response to silicone-hydrogel contact lenses

The thesis investigates the ocular response to silicone-hydrogel (SiH) contact lens wear, a relatively new contact lens material that has a higher modulus of rigidity and different surface coating than used in conventional hydrogel materials. The properties of SiH materials differ significantly from conventional hydrogels and, using subjective and objective means of assessment, the thesis examines how these properties affect reflection and biometry, ocular physiology, tear film characteristics, symptomatology, adverse events and complications. A range of standard and newly designed investigative techniques were employed, and latter involving novel imaging techniques, for the objective assessment of physiological changes which occur with contact lens wear. The study is the first to combine these techniques with biochemical analyses of the tear film composition. Forty-seven subjects were fitted with SiH lenses and randomly allocated to one of the two materials currently on the market (Lotrafilcon A or Balafilcon A) on an either daily or continuous wear basis. An additional control group of 14 age-matched non-contact lens wearers were monitored over the same period. Measurements were taken before and 1, 3, 6, 12 and 18 months after initial fitting. The findings reported in this thesis will enable contact lens practitioners and manufacturers to understand further the optical, physiological and biochemical nature of the ocular response to SiH contact lenses and hence facilitate the development of this important generation of contact lens material.

Disciplinary talk:a systemic functional exploration of university seminar discussions

Despite the growth of spoken academic corpora in recent years, relatively little is known about the language of seminar discussions in higher education. This thesis compares seminar discussions across three disciplinary areas. The aim of this thesis is to uncover the functions and patterns of talk used in different disciplinary discussions and to highlight language on a macro and micro level that would be useful for materials design and teaching purposes. A framework for identifying and analysing genres in spoken language based on Hallidayan Systemic Functional Linguistics (SFL) is used. Stretches of talk sharing a similar purpose and predictable functional staging, termed Discussion Macro Genres (DMGs) are identified. Language is compared across DMGs and across disciplines through use of corpus techniques in conjunction with SFL genre theory. Data for the study comprises just over 180,000 tokens and is drawn from the British Academic Spoken English corpus (BASE), recorded at two universities in the UK. The discipline areas investigated are Arts and Humanities, Social Sciences and Physical Sciences. Findings from this study make theoretical, empirical and methodological contributions to the field of spoken EAP. The empirical findings are firstly, that the majority of the seminar discussion can be assigned to one of the three main DMG in the corpus: Responding, Debating and Problem Solving. Secondly, it characterises each discipline area according to two DMGs. Thirdly, the majority of the discussion is non-oppositional in nature, suggesting that ‘debate’ is not the only form of discussion that students need to be prepared for. Finally, while some characteristics of the discussion are tied to the DMG and common across disciplines, others are discipline specific. On a theoretical level, this study shows that an SFL genre model for investigating spoken discourse can be successfully extended to investigate longer stretches of discourse than have previously been identified. The methodological contribution is to demonstrate how corpus techniques can be combined with SFL genre theory to investigate extended stretches of spoken discussion. The thesis will be of value to those working in the field of teaching spoken EAP/ ESAP as well as to materials developers.

How employer and employee satisfaction affect customer satisfaction:an application to franchise services

In small-service settings, how do owner satisfaction, front-line employee satisfaction, and customer satisfaction relate to one another? The authors use generalized exchange theory (GET) to examine how satisfaction levels of these three constituents are reciprocated. The authors examine a European franchise system comprising 50 outlets, 933 employees, and 20,742 customers. Their results show two important findings. First, the effect of owner-franchisee's satisfaction on customer satisfaction is fully mediated by front-line employee satisfaction. Thus, managers of a service outlet can strongly impact the satisfaction and behavioral intentions of their customer base, even without direct contact with them. Second, the link between customer satisfaction and purchase intention is moderated by employee satisfaction at an outlet. The link between customer satisfaction and customer purchase intentions is almost twice as strong when employees are satisfied than when they are not. Thus, there is a "doublepositive effect:" not only does higher employee satisfaction at an outlet directly lead to higher customer satisfaction but it also indirectly strengthens the association between customer satisfaction and their repurchase intentions.

QT interval prolongation related to psychoactive drug treatment:a comparison of monotherapy versus polytherapy

Background - Several antipsychotic agents are known to prolong the QT interval in a dose dependent manner. Corrected QT interval (QTc) exceeding a threshold value of 450 ms may be associated with an increased risk of life threatening arrhythmias. Antipsychotic agents are often given in combination with other psychotropic drugs, such as antidepressants, that may also contribute to QT prolongation. This observational study compares the effects observed on QT interval between antipsychotic monotherapy and psychoactive polytherapy, which included an additional antidepressant or lithium treatment. Method - We examined two groups of hospitalized women with Schizophrenia, Bipolar Disorder and Schizoaffective Disorder in a naturalistic setting. Group 1 was composed of nineteen hospitalized women treated with antipsychotic monotherapy (either haloperidol, olanzapine, risperidone or clozapine) and Group 2 was composed of nineteen hospitalized women treated with an antipsychotic (either haloperidol, olanzapine, risperidone or quetiapine) with an additional antidepressant (citalopram, escitalopram, sertraline, paroxetine, fluvoxamine, mirtazapine, venlafaxine or clomipramine) or lithium. An Electrocardiogram (ECG) was carried out before the beginning of the treatment for both groups and at a second time after four days of therapy at full dosage, when blood was also drawn for determination of serum levels of the antipsychotic. Statistical analysis included repeated measures ANOVA, Fisher Exact Test and Indipendent T Test. Results - Mean QTc intervals significantly increased in Group 2 (24 ± 21 ms) however this was not the case in Group 1 (-1 ± 30 ms) (Repeated measures ANOVA p < 0,01). Furthermore we found a significant difference in the number of patients who exceeded the threshold of borderline QTc interval value (450 ms) between the two groups, with seven patients in Group 2 (38%) compared to one patient in Group 1 (7%) (Fisher Exact Text, p < 0,05). Conclusions - No significant prolongation of the QT interval was found following monotherapy with an antipsychotic agent, while combination of these drugs with antidepressants caused a significant QT prolongation. Careful monitoring of the QT interval is suggested in patients taking a combined treatment of antipsychotic and antidepressant agents.

The multiple pheromone ant clustering algorithm and its application to real world domains

The Multiple Pheromone Ant Clustering Algorithm (MPACA) models the collective behaviour of ants to find clusters in data and to assign objects to the most appropriate class. It is an ant colony optimisation approach that uses pheromones to mark paths linking objects that are similar and potentially members of the same cluster or class. Its novelty is in the way it uses separate pheromones for each descriptive attribute of the object rather than a single pheromone representing the whole object. Ants that encounter other ants frequently enough can combine the attribute values they are detecting, which enables the MPACA to learn influential variable interactions. This paper applies the model to real-world data from two domains. One is logistics, focusing on resource allocation rather than the more traditional vehicle-routing problem. The other is mental-health risk assessment. The task for the MPACA in each domain was to predict class membership where the classes for the logistics domain were the levels of demand on haulage company resources and the mental-health classes were levels of suicide risk. Results on these noisy real-world data were promising, demonstrating the ability of the MPACA to find patterns in the data with accuracy comparable to more traditional linear regression models. © 2013 Polish Information Processing Society.

Bridging large and small scales of water models using hybrid Molecular Dynamics/Fluctuating Hydrodynamics framework

This thesis presents a two-dimensional water model investigation and development of a multiscale method for the modelling of large systems, such as virus in water or peptide immersed in the solvent. We have implemented a two-dimensional ‘Mercedes Benz’ (MB) or BN2D water model using Molecular Dynamics. We have studied its dynamical and structural properties dependence on the model’s parameters. For the first time we derived formulas to calculate thermodynamic properties of the MB model in the microcanonical (NVE) ensemble. We also derived equations of motion in the isothermal–isobaric (NPT) ensemble. We have analysed the rotational degree of freedom of the model in both ensembles. We have developed and implemented a self-consistent multiscale method, which is able to communicate micro- and macro- scales. This multiscale method assumes, that matter consists of the two phases. One phase is related to micro- and the other to macroscale. We simulate the macro scale using Landau Lifshitz-Fluctuating Hydrodynamics, while we describe the microscale using Molecular Dynamics. We have demonstrated that the communication between the disparate scales is possible without introduction of fictitious interface or approximations which reduce the accuracy of the information exchange between the scales. We have investigated control parameters, which were introduced to control the contribution of each phases to the matter behaviour. We have shown, that microscales inherit dynamical properties of the macroscales and vice versa, depending on the concentration of each phase. We have shown, that Radial Distribution Function is not altered and velocity autocorrelation functions are gradually transformed, from Molecular Dynamics to Fluctuating Hydrodynamics description, when phase balance is changed. In this work we test our multiscale method for the liquid argon, BN2D and SPC/E water models. For the SPC/E water model we investigate microscale fluctuations which are computed using advanced mapping technique of the small scales to the large scales, which was developed by Voulgarakisand et. al.

Novel neuronal and astrocytic mechanisms in thalamocortical loop dynamics

In this review, we summarize three sets of findings that have recently been observed in thalamic astrocytes and neurons, and discuss their significance for thalamocortical loop dynamics. (i) A physiologically relevant ‘window’ component of the low–voltage–activated, T–type Ca2+ current (ITwindow) plays an essential part in the slow (less than 1 Hz) sleep oscillation in adult thalamocortical (TC) neurons, indicating that the expression of this fundamental sleep rhythm in these neurons is not a simple reflection of cortical network activity. It is also likely that ITwindow underlies one of the cellular mechanisms enabling TC neurons to produce burst firing in response to novel sensory stimuli. (ii) Both electrophysiological and dye–injection experiments support the existence of gap junction–mediated coupling among young and adult TC neurons. This finding indicates that electrical coupling–mediated synchronization might be implicated in the high and low frequency oscillatory activities expressed by this type of thalamic neuron. (iii) Spontaneous intracellular Ca2+ ([Ca2+]i) waves propagating among thalamic astrocytes are able to elicit large and long–lasting N–methyl–D–aspartate–mediated currents in TC neurons. The peculiar developmental profile within the first two postnatal weeks of these astrocytic [Ca2+]i transients and the selective activation of these glutamate receptors point to a role for this astrocyte–to–neuron signalling mechanism in the topographic wiring of the thalamocortical loop. As some of these novel cellular and intracellular properties are not restricted to thalamic astrocytes and neurons, their significance may well apply to (patho)physiological functions of glial and neuronal elements in other brain areas.

Distances between Predicates in By-Analogy Reasoning Systems

The purpose is to develop expert systems where by-analogy reasoning is used. Knowledge “closeness” problems are known to frequently emerge in such systems if knowledge is represented by different production rules. To determine a degree of closeness for production rules a distance between predicates is introduced. Different types of distances between two predicate value distribution functions are considered when predicates are “true”. Asymptotic features and interrelations of distances are studied. Predicate value distribution functions are found by empirical distribution functions, and a procedure is proposed for this purpose. An adequacy of obtained distribution functions is tested on the basis of the statistical 2 χ –criterion and a testing mechanism is discussed. A theorem, by which a simple procedure of measurement of Euclidean distances between distribution function parameters is substituted for a predicate closeness determination one, is proved for parametric distribution function families. The proposed distance measurement apparatus may be applied in expert systems when reasoning is created by analogy.

Leveraging Existing Plasma Simulation Codes

This paper describes the process of wrapping existing scientific codes in the domain of plasma physics simulations through the use of the Sun’s Java Native Interface. We have created a Java front-end for a particular functionality, offered by legacy native libraries, in order to achieve reusability and interoperability without having to rewrite these libraries. The technique, introduced in this paper, includes two approaches – the one-to-one mapping for wrapping a number of native functions, and using peer classes for wrapping native data structures.

On Li’s Coefficients for Some Classes of L-Functions

AMS Subj. Classification: 11M41, 11M26, 11S40

Differential effectiveness of two anxiety induction procedures in youth and older adult populations

In this study, we tested in older and younger adults the efficacy of two well-known procedures to experimentally induce anxiety: a) Velten self-statements combined with music; b) film scenes. We extended the pre-vious findings in this field to the understudied area of mood induction in older adults. Fifty-seven older adults and 94 college students were random-ly assigned to one of the experimental conditions or to a control group. Results indicated that both procedures were effective, according to a series of ANOVAs for several self-report, physiological, and behavioral measures. Likewise, the highest effect sizes were observed for the Velten procedure (g = .81 vs. g = .71), and the effects were significantly higher in younger (g = 1.0 in the Velten condition) than in older adults (g = .62), Q = 4.25, X2(1), p = .0392. Both procedures were effective to induce inducting anxiety in both age groups, especially the Velten procedure in younger adults. Therefore, Velten self-statements combined with music may be very useful anxiety induction procedure for further research in controlled situa-tions of emotions across the life-span.

Target/error overlap in jargonaphasia:the case for a one-source model, lexical and non-lexical summation, and the special status of correct responses

We present three jargonaphasic patients who made phonological errors in naming, repetition and reading. We analyse target/response overlap using statistical models to answer three questions: 1) Is there a single phonological source for errors or two sources, one for target-related errors and a separate source for abstruse errors? 2) Can correct responses be predicted by the same distribution used to predict errors or do they show a completion boost (CB)? 3) Is non-lexical and lexical information summed during reading and repetition? The answers were clear. 1) Abstruse errors did not require a separate distribution created by failure to access word forms. Abstruse and target-related errors were the endpoints of a single overlap distribution. 2) Correct responses required a special factor, e.g., a CB or lexical/phonological feedback, to preserve their integrity. 3) Reading and repetition required separate lexical and non-lexical contributions that were combined at output.

The value of magnetoencephalography to guide electrode implantation in epilepsy

Purpose: To investigate if magnetoencephalography (MEG) can identify implantation sites for intracranial recordings (IR). Method: Two groups of 12 patients assessed for surgery with IR with and without MEG were compared (MEG and control groups). In the control group, non-invasive presurgical assessment without MEG suggested clear hypotheses for implantation. In the MEG group, non-invasive assessment was inconclusive, and MEG was used to identify implantation sites. Both groups were matched for implantation type. The success of implantation was defined by findings in IR: a) Focal seizure onset; b)Unilateral focal abnormal responses to single pulse electrical stimulation(SPES); and c) Concordance between a) and b). Results: In all MEG patients, at least one virtual MEG electrode generated suitable hypotheses for the location of implantations. The proportion of patients showing focal seizure onset restricted to one hemisphere was similar in control and MEG groups (6/12 vs. 11/12, Fisher’s exact test,p = 0.0686). The proportion of patients showing unilateral responses to SPES was lower in the control than in the MEG group (7/12 vs. 12/12,p = 0.0373). Conclusion: The MEG group showed similar or higher incidence of successful implantations than controls.

Resonance properties of domain boundaries in quasi-two dimensional antiferromagnets

The so-called "internal modes" localized near the domain boundaries in quasi-two dimensional antiferromagnets are investigated. The possible localized states are classified and their frequency dependences on the system discreteness parameter λ=J/β, which describes the ratio of the magnitudes of the exchange interplane interaction and the magnetic anisotropy, are found. A sudden change in the spectrum of the local internal modes is observed at a critical value of this parameter, λ=λb=3/4, where the domain wall shifts from a collinear to a canted shape. When λ<λb there are one symmetric and two antisymmetric local modes, and when λ>λb the modes are two symmetric, one antisymmetric, and one shear. For discreteness parameters close to the critical value, the frequencies of some of the local modes lie deep inside the gap for the linear AFM magnon spectrum and can be observed experimentally. © 2010 American Institute of Physics.

Investigating the ability of antibodies to recognize specific oxidized protein epitopes

There is a growing awareness that inflammatory diseases have an oxidative pathology, which can result in specific oxidation of amino acids within proteins. Antibody-based techniques for detecting oxidative posttranslational modifications (oxPTMs) are often used to identify the level of protein oxidation. There are many commercially available antibodies but some uncertainty to the potential level of cross reactivity they exhibit; moreover little information regarding the specific target epitopes is available. The aim of this work was to investigate the potential of antibodies to distinguish between select peptides with and without oxPTMs. Two peptides, one containing chlorotyrosine (DY-Cl-EDQQKQLC) and the other an unmodified tyrosine (DYEDQQKQLC) were synthesized and complementary anti-sera were produced in sheep using standard procedures. The anti-sera were tested using a half-sandwich ELISA and the anti-serum raised against the chloro-tyrosine containing peptide showed increased binding to the chlorinated peptide, whereas the control anti-serum bound similarly to both peptides. This suggested that antibodies can discriminate between similar peptide sequences with and without an oxidative modification. A peptide (STSYGTGC) and its variants with chlorotyrosine or nitrotyrosine were produced. The anti-sera showed substantially less binding to these alternative peptides than to the original peptides the anti-sera were produced against. Work is ongoing to test commercially available antibodies against the synthetic peptides as a comparison to the anti-sera produced in sheep. In conclusion, the antisera were able to distinguish between oxidatively modified and unmodified peptides, and two different sequences around the modification site.