An Investigation of Firm Heterogeneity in the Constraints to Development and Growth in Pakistan

This study considers the importance of firm characteristics in explaining the degree of business constraints facing Pakistani firms in the Investment Climate Survey. We quantify how firms with differing characteristics experience particular problems. After controlling for other factors, the largest differences in responses to business constraints occur among firms that vary by manufacturing industry, and among firms operating under different ownership structures or selling in different markets. In some cases, firm size and firm location also play an important role. The age of the firm generally does not lead to significant differences. These results account for the heterogeneity of firms better than others, and may be important for policy-makers to develop more specific approaches to fostering the investment climate.Pakistan, Investment Climate, Business Constraints

Structure property relationships in electron donating systems for potential photovoltaic applications.

Conjugated polymers are considered to be one-dimensional semiconductors. In conjugated polymers single and double bonds alternatively bond the carbon atoms along the polymer chain. The loosely bound electrons determine the electronic properties of conjugated polymers. In order to utilise the properties of conjugated polymers in terms of a photovoltaic (PV) device application an acceptor material must be added. The acceptor material used in this study is used in buckminsterfullerence (C60). C60 was selected for this purpose due to its size and the fact that it can accept up to six additional electrons. Ultrafast charge transfers from a conducting polymer onto C60 were first reported in 1992 by Sariciftci et al. in a blend of MEH-PPV (poly (2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylenevinylene) and since then it’s properties as an electron acceptor have been widely investigated. The debate of the exact mechanism of the charge transfer in polymer/fullerence blends is still on going today. The investigation of these systems is predominantly done using time resolved spectroscopy (photoinducted absorption, PIA), which is still considered to be the most effective way of investigation charge transfer between polymer/fullerence composites. However time resolved spectroscopy is expensive and is not readily available for use. The aim of this study is to explore charge transfer signatures in polymer/fullerence composites without using PIA spectroscopy. This study proposes to use steady state spectroscopic techniques coupled with electrochemical and conductivity measurements to characterise charge transfer signatures in polymer fullerence composites. The much studied MEH-PPV/C60 model system was initially employed in a systematic approach to try and elucidate charge transfer indicators between the polymers and C60 Fluorescence spectroscopy, cyclic volammetry, spectroelectrochemical and conductivity measurements provided evidence of charge transfer signatures in the model composite and were seen to be potentially viable techniques for assessing novel systems. The study was then extended to a homologous series of polymers which have continuously varying electronic and optical properties. The polymer series was synthesised in house and characterised for the first time in the solid state as part of this work. Electronic spectroscopy of the polymer series revealed that aggregation was recurring in the solid state form of the polymers. The electronic properties of the molecular and solid-state forms are different and the structure property relationships previously determined for the molecular forms could not be applied to the solid-state. It was observed that emission spectra of the polymers were all seen to be red shifted compared to those of their isolated molecular form. The fluorescence yield was also low, which also confirmed that there are aggregates within the polymers in their solid-state form. Cyclic volammetry measurements allowed calculation of the exact positioning of the HOMO-LUMO levels of each polymer. The precise levels of the HOMO-LUMO levels are important when matching the energy levels of the polymer to the energy levels of C60. Electrochemical bandgaps were in close accordance to the optical bandgaps. In-situ spectroelectrochemical measurements allowed observations of the bipolaron energy states of each polymer. Electroabsorption studies showed that each polymer was dominated by the quadratic Stark effect. The electroabsorption spectrum of each polymer closely resembled a first derivative lineshape of it’s absorption spectrum indicating a dominance of intramolecular transitions within each of the polymers. Using two of the new polymers a synthetic probe of the charge transfer mechanism was obtained. Charge transfer markers were evident in the new composites using fluorescence spectroscopy, cyclic volammetry, spectroelectrochemical measurements and conductivity measurements. For the results it was seen that the interaction of the two polymers with the C60 varied. From this systematic approach it was possible to observe which of the polymers showed the most potential for a device application by matching of the appropriate energy levels to achieve a more efficient charge transfer. In general it can be said that using a approach it was possible to match up the energy levels of a polymer/fullerence composite in order to achieve a more efficient interaction, which can be measured without the need for time resolved spectroscopy

Analysis of a Thin-Walled Curved Rectangular Beam with Five Degrees of Freedom

A study of a thin-walled curved rectangular box beam under torsion and out-of-plane bending is documented in this thesis. A new one-dimensional theory that takes into account warping and distortion in the beam cross-sections is the main focus. Existing available theories for thin-walled curved beams lack rigorous theoretical development, and most have ignored the effects of warping and distortion. A higher order theory including two additional degrees of freedom corresponding to warping and distortion was derived. The conventional three degrees of freedom model was compared with the new five degrees of freedom model. The variation of beam thickness to control and decrease the high distortion variable is investigated

Topological models of swarming

We study the collective behaviour of animal aggregations, swarming, using theoretical models of collective motion. Focusing on bird flocking, we aim to reproduce two main aspects of real world aggregations: cohesion and coalignment. Following the observation that interactions between birds in the flock does not have a characteristic length-scale, we concentrate on topological, metric-free models of collective motion. We propose and analyse three novel models of swarming: two based on topological interactions between particles, which define interacting neighbours based on Voronoi tessellation of the group of particles, and one which uses the visual field of the agent. We explore the problem of cohesion, bounding of topological flocks in free space, by introducing the mechanism of neighbour anticipation. This relies on going towards the inferred future position of an individuals neighbours and results in providing the bounding forces for the group. We also address the issue of unrealistic density distributions in existing metric-free models by introducing a homogeneous, tunable motional bias throughout the swarm. The proposed model produces swarms with density distributions corresponding to empirical data from flocks of Starlings. Furthermore, we show that for a group with a visual information input and individuals moving so as to seek marginal opacity that alignment and group cohesion can be induced without the need for explicit aligning interaction rules between group members. For each of the proposed models a comprehensive analysis of characteristics and behaviour under different parameter sets is performed

An auto-titrating (intelligent) oxygen system in patients with chronic respiratory failure

Long-term oxygen therapy (LTOT) improves survival in patients with chronic obstructive pulmonary disease (COPD) and chronic hypoxaemia with international guidelines recommending LTOT for patients with chronic hypoxaemia secondary to respiratory failure. LTOT is prescribed at a fixed-flow rate aiming to maintain the partial pressure of oxygen ≥8 kilopascals or oxygen saturations (SpO2) >90% at rest. However, many patients on domiciliary LTOT continue to experience episodes of intermittent hypoxia (SpO2 <90%) during rest, exercise, activities of daily living (ADL) and sleep with the potentially harmful consequences of arrhythmias, ischaemic heart disease, transient increases in pulmonary pressures and reduced cerebral oxygenation. The aim of this thesis was to explore whether a novel smartphone based auto-titrating oxygen system (the intelligent oxygen therapy system [iO2Ts]), could reduce intermittent hypoxia by delivering variable flow oxygen to maintain a pre-set SpO2 target during various activities which typically take place over a period of 24 hours. In the first study, the iO2Ts significantly reduced intermittent hypoxia compared to ambulatory oxygen in patients with COPD on LTOT during a 6-minute walk test (6MWT). The second study showed that the iO2Ts is equivalent to ambulatory oxygen in reducing intermittent hypoxia during a 6MWT in patients with interstitial lung disease (a group of patients who rapidly desaturate on exercise). The third study showed that the iO2Ts reduced intermittent hypoxia during ADL in patients on LTOT compared to usual LTOT. In a fourth pilot study, the iO2Ts maintained oxygenation as well as usual LTOT and did not change transcutaneous carbon dioxide levels compared to LTOT during sleep. In summary, this thesis has shown that the iO2Ts can reduced intermittent hypoxia in patients on LTOT during various activities which typically take place over 24 hours. The reduction in intermittent hypoxia could optimise domiciliary and ambulatory oxygen for patients on LTOT.Open Acces

An Investigation of Firm Heterogeneity in the Constraints to Development and Growth in Pakistan

This study considers the importance of firm characteristics in explaining the degree of business constraints facing Pakistani firms in the Investment Climate Survey. We quantify how firms with differing characteristics experience particular problems. After controlling for other factors, the largest differences in responses to business constraints occur among firms that vary by manufacturing industry, and among firms operating under different ownership structures or selling in different markets. In some cases, firm size and firm location also play an important role. The age of the firm generally does not lead to significant differences. These results account for the heterogeneity of firms better than others, and may be important for policy-makers to develop more specific approaches to fostering the investment climate

Mistranslation of the Genetic Code

During mRNA decoding at the ribosome, deviations from stringent codon identity, or “mistranslation,” are generally deleterious and infrequent. Observations of organisms that decode some codons ambiguously, and the discovery of a compensatory increase in mistranslation frequency to combat environmental stress have changed the way we view “errors” in decoding. Modern tools for the study of the frequency and phenotypic effects of mistranslation can provide quantitative and sensitive measurements of decoding errors that were previously inaccessible. Mistranslation with non‐protein amino acids, in particular, is an enticing prospect for new drug therapies and the study of molecular evolution

Employing James Gee’s Analytic Lens for Identity to Investigate Teacher Identity Development

The current article is an exploration of the construction and development of teacher identities at the tertiary level in Pakistan. Identity is the sense of who one is as a professional, and it is becoming evident that it is important for teachers at all levels to develop a clear sense of identity as it leads to better practices and high level of commitment to the profession. The researcher adopted a constructivist stance for the investigation of identity and used data triangulation by using life histories, semi-structured interviews (based on the James Gee’s Lens for Identity) and fieldnotes as the sources of data. Six participants from urban tertiary institutions in various cities of Pakistan were selected and interviewed. The gathered data was analyzed iteratively through coding and contrastive analysis and highlighted the similarities and disparities of the various perspectives of identity; it was discovered that the participants had a better awareness and acceptance of their nature identity, whereas the institutional and discursive identities were the ones that posed conflict for them. The researcher also found that affinity identity was the weakest link in the Gee lens for teachers of Pakistan

An Activating Mutation in sos-1 Identifies Its Dbl Domain as a Critical Inhibitor of the Epidermal Growth Factor Receptor Pathway during Caenorhabditis elegans Vulval Development

Proper regulation of receptor tyrosine kinase (RTK)-Ras-mitogen-activated protein kinase (MAPK) signaling pathways is critical for normal development and the prevention of cancer. SOS is a dual-function guanine nucleotide exchange factor (GEF) that catalyzes exchange on Ras and Rac. Although the physiologic role of SOS and its CDC25 domain in RTK-mediated Ras activation is well established, the in vivo function of its Dbl Rac GEF domain is less clear. We have identified a novel gain-of-function missense mutation in the Dbl domain of Caenorhabditis elegans SOS-1 that promotes epidermal growth factor receptor (EGFR) signaling in vivo. Our data indicate that a major developmental function of the Dbl domain is to inhibit EGF-dependent MAPK activation. The amount of inhibition conferred by the Dbl domain is equal to that of established trans-acting inhibitors of the EGFR pathway, including c-Cbl and RasGAP, and more than that of MAPK phosphatase. In conjunction with molecular modeling, our data suggest that the C. elegans mutation, as well as an equivalent mutation in human SOS1, activates the MAPK pathway by disrupting an autoinhibitory function of the Dbl domain on Ras activation. Our work suggests that functionally similar point mutations in humans could directly contribute to disease