Mathematical Modeling of Arterial Blood Pressure Using Photo-Plethysmography Signal in Breath-hold Maneuver

Recent research has shown that each apnea episode results in a significant rise in the beat-to-beat blood pressure and by a drop to the pre-episode levels when patient resumes normal breathing. While the physiological implications of these repetitive and significant oscillations are still unknown, it is of interest to quantify them. Since current array of instruments deployed for polysomnography studies does not include beat-to-beat measurement of blood pressure, but includes oximetry, it is both of clinical interest to estimate the magnitude of BP oscillations from the photoplethysmography (PPG) signal that is readily available from sleep lab oximeters. We have investigated a new method for continuous estimation of systolic (SBP), diastolic (DBP), and mean (MBP) blood pressure waveforms from PPG. Peaks and troughs of PPG waveform are used as input to a 5th order autoregressive moving average model to construct estimates of SBP, DBP, and MBP waveforms. Since breath hold maneuvers are shown to simulate apnea episodes faithfully, we evaluated the performance of the proposed method in 7 subjects (4 F; 32+-4 yrs., BMI 24.57+-3.87 kg/m2) in supine position doing 5 breath maneuvers with 90s of normal breathing between them. The modeling error ranges were (all units are in mmHg) -0.88+-4.87 to -2.19+-5.73 (SBP); 0.29+-2.39 to -0.97+-3.83 (DBP); and -0.42+-2.64 to -1.17+-3.82 (MBP). The cross validation error ranges were 0.28+-6.45 to -1.74+-6.55 (SBP); 0.09+-3.37 to -0.97+-3.67 (DBP); and 0.33+-4.34 to -0.87+-4.42 (MBP). The level of estimation error in, as measured by the root mean squared of the model residuals, was less than 7 mmHgComment: 4 pages, published in 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC

The role of institutional logics in shaping firm practices: the case of corporate governance and corporate social responsibility

This thesis investigates the role of institutional logics, as hidden drivers of firm behaviour, in shaping firm practices and decisions on corporate governance configurations and engagement in corporate social responsibility. It adopts a quantitative approach to identify and assess the embeddedness of family and market (non-family) logics in firm decision making, incorporating several behavioural dimensions in terms of real firm practices that are empirically proven to differ between family and non-family firms. The thesis builds on the socioemotional wealth preservation perspective regarding displaying family or non-family firm-like behaviour, and develops a new, institutional-based classification of firms, comprising family logic-driven and market logic-driven firms that draw from the notion of firm logic orientation – a latent explanatory, institutional factor. This institutional-based approach suggests a distinct view of the familiness and non-familiness, or marketness, of firms irrespective of ownership status (family or not). Particularly, this thesis emphasises that it is not family ownership status (or not), but the firm practices and behaviour that characterise and define firms in terms of their distinctive culture and nature. Using US-based data of firms listed on the S&P 1500 index in the period of 2006–2016, it tests the main and moderation effects of firm logic orientation through the empirical windows of corporate governance and corporate social responsibility. The analysis finds that family logic-driven firms differ from market logic-driven firms regarding the firm choice of internal corporate governance configurations and the magnitude of the established corporate governance determinant-configuration relationships. Specifically, relative to market logic-driven firms, family logic-driven firms appoint smaller and less independent boards and pay top managers lower total and equity-based compensation. Moreover, compared with the marketness logic orientation, the familiness of firms mitigates the effect of corporate governance determinants, including firm-specific, managerial and governance characteristics, on corporate governance configurations concerning the structure of the board of directors and the design of executive compensation. The findings also show that family logic-driven and market logic-driven firms vary in terms of the firm social performance of corporate social responsibility and the magnitude of the relationship between strategic conformity ¬– a legitimacy-seeking activity – and corporate social responsibility performance. Particularly, relative to market logic-driven firms, family logic-driven firms perform worse regarding firm engagement in corporate social responsibility. However, relative to the marketness logic orientation, the familiness of firms amplifies the social gains derived from firm legitimacy in relation to improving the perception of firms’ corporate social responsibility. This mitigates the otherwise negative impact of familiness logic orientation on corporate social responsibility performance. The findings indicate that, driving firm behaviour, the familiness logic orientation of firms presents a distinct, family-oriented business form that, apart from family ownership status (or not), differentiates firms from the standard, shareholder-oriented view of firms – so-called marketness logic orientation – in terms of firm practices and decisions. This implies that the latent institutional factor of firm logic orientation matters at least as much as the facet of ownership status for firm practices and behaviour. This thesis is one of the first to quantitatively measure the embeddedness of institutional logics – an intangible construct – in firm decision making based on the level of observed firm practices as a tangible manifestation of namely family and market logics, and to empirically examine the influence of family and market logics on firm practices and behaviour in the contexts of corporate governance and corporate social responsibility

Optimized Distributed Processing in a Vehicular Cloud Architecture

The introduction of cloud data centres has opened new possibilities for the storage and processing of data, augmenting the limited capabilities of peripheral devices. Large data centres tend to be located away from the end users, which increases latency and power consumption in the interconnecting networks. These limitations led to the introduction of edge processing where small-distributed data centres or fog units are located at the edge of the network close to the end user. Vehicles can have substantial processing capabilities, often un-used, in their on-board-units (OBUs). These can be used to augment the network edge processing capabilities. In this paper, we extend our previous work and develop a mixed integer linear programming (MILP) formulation that optimizes the allocation of networking and processing resources to minimize power consumption. Our edge processing architecture includes vehicular processing nodes, edge processing and cloud infrastructure. Furthermore, in this paper our optimization formulation includes delay. Compared to power minimization, our new formulation reduces delay significantly, while resulting in a very limited increase in power consumption

Internal Corporate Governance Mechanisms and Firm Performance: Evidence from GCC Countries

Across three empirical studies, this thesis investigates the relationship between internal corporate governance mechanisms and firm performance, measured by Tobin‟s Q and market to book value of total equity, in the six Gulf Co-operation Council (GCC) countries. The thesis is motivated by central theories of corporate governance, several gaps in the literature, and the recent rapid growth of the GCC stock markets. The research employs data samples covering all GCC listed companies between the years 2012 and 2016, for which data are available. The first empirical study investigates the impact of overall ownership concentration on firm performance and finds a significant positive impact. As the objectives of share ownership vary by owner identity, ownership concentration is divided into four identity categories, namely: government, institutional, corporate, and individual/family. While government ownership concentration is found to have a significant negative performance effect, institutional ownership concentration, corporate ownership concentration, and individual/family ownership concentration are all found to have a significant positive performance effect. The second empirical study examines the effect of five board characteristics on firm performance. The results indicate that board activity and CEO duality do not have a significant effect on firm performance, while board size and board remuneration have a significant positive effect on firm performance. In contrast, board independence is found to have a negative performance effect. The relationships between the main variables in the first two studies suffer from endogeneity, reverse causality bias in particular, and this is controlled for with an instrumental variables approach, using a two-stage least squares estimator. In the third study, endogeneity bias is caused by unobserved heterogeneity, and this is controlled for using a two-way fixed effects estimator. The third empirical study investigates the impact of founder ownership concentration and founder board of director presence on firm performance. The results indicate that founder ownership concentration has no significant effect on firm performance when the founders are the government, institutions, or mixed. However, family founder ownership concentration has a significant positive performance effect, and royal family founder ownership concentration has a significant negative performance effect. The presence of family founders and royal family founders on boards of directors is found to have no significant effect on firm performance. Notably, the third empirical study contributes to the corporate governance field of research in general by introducing the dimensions of royal family founder ownership and royal family founder board of director presence

Pre-clinical evaluation of advanced nerve guide conduits using a novel 3D in vitro testing model

Autografts are the current gold standard for large peripheral nerve defects in clinics despite the frequentlyoccurring side effects like donor site morbidity. Hollow nerve guidance conduits (NGC) are proposed alternatives toautografts, but failed to bridge gaps exceeding 3 cm in humans. Internal NGC guidance cues like microfibresare believed to enhance hollow NGCs by giving additional physical support for directed regeneration of Schwann cellsand axons. In this study, we report a new 3D in vitro model that allows the evaluation of different intraluminal fibrescaffolds inside a complete NGC. The performance of electrospun polycaprolactone (PCL) microfibres inside 5 mmlong polyethylene glycol (PEG) conduits were investigated in neuronal cell and dorsal root ganglion (DRG) cultures invitro. Z-stack confocal microscopy revealed the aligned orientation of neuronal cells along the fibres throughout thewhole NGC length and depth. The number of living cells in the centre of the scaffold was not significantly different tothe tissue culture plastic (TCP) control. For ex vivo analysis, DRGs were placed on top of fibre-filled NGCs to simulatethe proximal nerve stump. In 21 days of culture, Schwann cells and axons infiltrated the conduits along the microfibreswith 2.2 ± 0.37 mm and 2.1 ± 0.33 mm, respectively. We conclude that this in vitro model can help define internal NGCscaffolds in the future by comparing different fibre materials, composites and dimensions in one setup prior to animaltesting

Energy-Efficient Distributed Processing in Vehicular Cloud Architecture

Facilitating the revolution for smarter cities, vehicles are getting smarter and equipped with more resources to go beyond transportation functionality. On-Board Units (OBU) are efficient computers inside vehicles that serve safety and non-safety based applications. However, much of these resources are underutilised. On the other hand, more users are relying now on cloud computing which is becoming costly and energy consuming. In this paper, we develop a Mixed Integer linear Programming (MILP) model that optimizes the allocation of processing demands in an architecture that encompasses the vehicles, edge and cloud computing with the objective of minimizing power consumption. The results show power savings of 70% - 90% compared to conventional clouds for small demands. For medium and large demand sizes, the results show 20% - 30% power saving as the cloud was used partially due to capacity limitations on the vehicular and edge nodes

A Comparative Interaction between Copper Ions with Alzheimer's β

The interaction of Cu2+ with the first 16 residues of the Alzheimer's amyliod β peptide, Aβ(1–16), and human serum albumin (HSA) were studied in vitro by isothermal titration calorimetry at pH 7.2 and 310 K in aqueous solution. The solvation parameters recovered from the extended solvation model indicate that HSA is involved in the transport of copper ion. Complexes between Aβ(1–16) and copper ions have been proposed to be an aberrant interaction in the development of Alzheimer's disease, where Cu2+ is involved in Aβ(1–16) aggregation. The indexes of stability indicate that HSA removed Cu2+ from Aβ(1–16), rapidly, decreased Cu-induced aggregation of Aβ(1–16), and reduced the toxicity of Aβ(1–16) + Cu2+ significantly

Steam consumption minimization using genetic algorithm optimization method: an industrial case study

yesCondensate stabilization is a process where hydrocarbon condensate recovered from natural gas reservoirs is processed to meet the required storage, transportation, and export specifications. The process involves stabilizing of hydrocarbon liquid by separation of light hydrocarbon such as methane from the heavier hydrocarbon constituents such as propane. An industrial scale back-up condensate stabilization unit was simulated using Aspen HYSYS software and validated with the plant data. The separation process consumes significant amount of energy in form of steam. The objectives of the paper are to find the minimum steam consumption of the process and conduct sensitivity and exergy analyses on the process. The minimum steam consumption was found using genetic algorithm optimization method for both winter and summer conditions. The optimization was carried out using MATLAB software coupled with Aspen HYSYS software. The optimization involves six design variables and four constraints, such that realistic results are achieved. The results of the optimization show that savings in steam consumption is 34% as compared to the baseline process while maintaining the desired specifications. The effect of natural gas feed temperature has been investigated. The results show that steam consumption is reduced by 46% when the natural gas feed temperature changes from 17.7 to 32.7°C. Exergy analysis shows that exergy destruction of the optimized process is 37% less than the baseline process

Harnessing Polyhydroxyalkanoates and Pressurized Gyration for Hard and Soft Tissue Engineering

Organ dysfunction is a major cause of morbidity and mortality. Transplantation is typically the only definitive cure, challenged by the lack of sufficient donor organs. Tissue engineering encompasses the development of biomaterial scaffolds to support cell attachment, proliferation, and differentiation, leading to tissue regeneration. For efficient clinical translation, the forming technology utilized must be suitable for mass production. Herein, uniaxial polyhydroxyalkanoate scaffolds manufactured by pressurized gyration, a hybrid scalable spinning technique, are successfully used in bone, nerve, and cardiovascular applications. Chorioallantoic membrane and in vivo studies provided evidence of vascularization, collagen deposition, and cellular invasion for bone tissue engineering. Highly efficient axonal outgrowth was observed in dorsal root ganglion-based 3D ex vivo models. Human induced pluripotent stem cell derived cardiomyocytes exhibited a mature cardiomyocyte phenotype with optimal calcium handling. This study confirms that engineered polyhydroxyalkanoate-based gyrospun fibers provide an exciting and unique toolbox for the development of scalable scaffolds for both hard and soft tissue regeneration