Microbial production of 3-hydroxypropionic acid and poly(3-hydroxypropionate): Investigation of Lactobacillus reuteri propanediol utilization pathway enzymes

Concerns regarding environmental issues such as greenhouse gas emissions and climate change have led to a shift within the research community and chemical and energy industry sectors for finding sustainable routes for producing fuels and chemicals from renewable resources, thereby minimizing our dependence on petroleum. The C3-chemical 3-hydroxypropionic acid has been identifed as a top candidate for the biobased chemical industry. This platform chemical is a β-hydroxy acid containing two functional groups (hydroxyl and carboxyl) enabling its conversion into value-added chemicals such as 1,3-propanediol, acrolein, malonic acid, acrylamide and acrylic acid, which can be used in resins, coatings, paints, adhesives, lubricants, and in the textile industry as anti-static agent. Polymerized 3- HP, poly(3-hydroxypropionate) (poly(3-HP)), is a biodegradable and stable polymer which, besides its potential role as a biomaterial, can be degraded to 3-HP monomer. In recent years, a dramatic increase in the interest for microbial production of 3-HP and poly(3-HP) has been observed. Metabolic engineering and recombinant expression of various enzymatic pathways in a number of bacterial strains have been suggested and implemented, with mainly renewable glucose and glycerol as substrates. This thesis presents a novel pathway called the propanediol utilization pathway present in Lactobacillus reuteri that catalyzes dehydration of glycerol to 3- hydroxypropionaldehyde (3-HPA) and further to 3-HP by a series of reactions catalyzed by propionaldehyde dehydrogenase (PduP), phosphotransacylase (PduL) and propionate kinase (PduW). Through structural modeling and kinetic characterization of PduP, its 3-HPA consuming ability was confirmed and catalytic mechanism proposed. PduP, PduL and PduW-mediated conversion of 3-HPA to 3- HP was confirmed through their recombinant expression in Escherichia coli. 3-HPA produced from glycerol by L. reuteri was used as a substrate for conversion to 3-HP by the recombinant E. coli. A yield of 1 mol/mol was reached with a titer of 12 mM 3-HP. Depletion of the cofactor NAD+ required for the catalysis of 3-HP to 3-HPCoA, was deemed responsible for the low titer. Regeneration of NAD+, used up in PduP catalyzed reaction, was achieved by recombinant expression of NADH oxidase (Nox) from L. reuteri in E. coli expressing PduP, PduL and PduW. The final 3-HP titer by this recombinant strain was at least twice that of E. coli carrying solely PduP, PduL and PduW. For the production of poly(3-HP), PduL and PduW in the recombinant strain were replaced by polyhydroxyalkanoate synthase of Chromobacterium sp. that converts 3- HP-CoA to poly(3-HP). A poly(3-HP) content of up to 40% (w/w) cell dry weight was reached in an efficient and cheap process requring no additivies or expensive cofactors

The ‘whole-club capacity’ approach to athlete wellbeing & education : analysing competing logics within elite sporting organisations

With the aim of better understanding and supporting athlete’s experiences of wellbeing, this research project established two key research goals: 1) inquiry: to investigate and understand athlete-specific risk and protective factors, and 2) impact: to support the development of effective wellbeing supports in response to those factors. This research project, investigating a professional Australian rugby league football club, used one-on-one interviews, workshopbased interventions, and surveys, to evaluate athlete’s experiences of the Athlete Wellbeing & Education (AW&E) Framework employed by the Australian Rugby League (ARL). Guided by organisational logic theory, it explores the relationship between structure and agency at the individual, organisational, and institutional levels of analysis, and measures patterns of compatibility and centrality between wellbeing, performance, and commercial logics. The analysis demonstrates the need to embed a more transdisciplinary approach to holistic wellbeing within high performance (HP) systems and recognise the important protective role that HP members have within the athlete’s psychosocial support network. This thesis, informed by the ‘Whole-Club Capacity’ (WCC) Approach to AW&E, presents a philosophy of care that connects the full ecology of elite sporting organisations to the athlete’s experience of wellbeing, and articulates the reciprocal gains that effective wellbeing support systems can have on athletes’ performance, elite sporting organisations’ commercial interests, and on their duty of care/social responsibilities. It presents a number of pragmatic recommendations which could be implemented under the WCC Approach to AW&E, and includes two interventions (mental health literacy training and connection workshops) developed and evaluated within this project’s action research methodology. At its conclusion, this thesis presents a rationale for the need to de-stigmatise help-seeking within HP environments and strengthen athletes’ psychosocial supportive resources, and provides a range of subsequent strategies that elite sporting organisations can use to do so

Improving the performance of QoS models in MANETs through interference monitoring and correction

Mobile Ad hoc Networks (MANETs) have been proposed for a wide variety of applications, some of which require the support of real time and multimedia services. To do so, the network should be able to offer quality of service (QoS) appropriate for the latency and throughput bounds to meet appropriate real time constraints imposed by multimedia data. Due to the limited resources such as bandwidth in a wireless medium, flows need to be prioritised in order to guarantee QoS to the flows that need it. In this research, we propose a scheme to provide QoS guarantee to high priority flows in the presence of other high as well as low priority flows so that both type of flows achieve best possible throughput and end-to-end delays. Nodes independently monitor the level of interference by checking the rates of the highest priority flows and signal corrective mechanisms when these rates fall outside of specified thresholds. This research investigates using simulations the effects of a number of important parameters in MANETs, including node speed, pause time, interference, and the dynamic monitoring and correction on system performance in static and mobile scenarios. In this report we show that the dynamic monitoring and correction provides improved QoS than fixed monitoring and correction to both high priority and low priority flows in MANETs

Local climate change and the impacts on hydrological processes in an arid alpine catchment in Karakoram

Climate change and the impacts on hydrological processes in Karakoram region are highly important to the available water resources in downstream oases. In this study, a modified quantile perturbation method (QPM), which was improved by considering the frequency changes in different precipitation intensity ranges, and the Delta method were used to extract signals of change in precipitation and temperature, respectively. Using a historical period (1986-2005) for reference, an average ensemble of 18 available Global Circulation Models (GCMs) indicated that the annual precipitation will increase by 2.9-4.4% under Representative Concentration Pathway 4.5 (RCP4.5) and by 2.8-7.9% in RCP8.5 in different future periods (2020-2039, 2040-2059, 2060-2079 and 2080-2099) due to an increased intensity of extreme precipitation events in winter. Compared with the historical period, the average ensemble also indicated that temperature in future periods will increase by 0.31-0.38 degrees C/10a under RCP4.5 and by 0.34-0.58 degrees C/10a under RCP8.5. Through coupling with a well-calibrated MIKE SHE model, the simulations suggested that, under the climate change scenarios, increasing evaporation dissipation will lead to decreased snow storage in the higher altitude mountain region and likewise with regard to available water in the downstream region. Snow storage will vary among elevation bands, e.g., the permanent snowpack area below 5600 m will completely vanish over the period 2060-2079, and snow storage in 5600-6400 m will be reduced dramatically; however, little or no change will occur in the region above 6400 m. Warming could cause stronger spring and early summer stream runoff and reduced late summer flow due to a change in the temporal distribution of snowmelt. Furthermore, both the frequency and intensity of flooding will be enhanced. All the changes in hydrological processes are stronger under RCP8.5 than those under RCP4.5. In Karakoram region, the transformations among different forms of water resources alter the distributions of hydrologic components under future climate scenarios, and more studies are needed on the transient water resources system and the worsening of flood threats in the study area

Multiclass scheduling algorithms for the DAVID metro network

Abstract—The data and voice integration over dense wavelength-division-multiplexing (DAVID) project proposes a metro network architecture based on several wavelength-division-multiplexing (WDM) rings interconnected via a bufferless optical switch called Hub. The Hub provides a programmable interconnection among rings on the basis of the outcome of a scheduling algorithm. Nodes connected to rings groom traffic from Internet protocol routers and Ethernet switches and share ring resources. In this paper, we address the problem of designing efficient centralized scheduling algorithms for supporting multiclass traffic services in the DAVID metro network. Two traffic classes are considered: a best-effort class, and a high-priority class with bandwidth guarantees. We define the multiclass scheduling problem at the Hub considering two different node architectures: a simpler one that relies on a complete separation between transmission and reception resources (i.e., WDM channels) and a more complex one in which nodes fully share transmission and reception channels using an erasure stage to drop received packets, thereby allowing wavelength reuse. We propose both optimum and heuristic solutions, and evaluate their performance by simulation, showing that heuristic solutions exhibit a behavior very close to the optimum solution. Index Terms—Data and voice integration over dense wavelength-division multiplexing (DAVID), metropolitan area network, multiclass scheduling, optical ring, wavelength-division multiplexing (WDM). I

Traffic Engineering in G-MPLS networks with QoS guarantees

In this paper a new Traffic Engineering (TE) scheme to efficiently route sub-wavelength requests with different QoS requirements is proposed for G-MPLS networks. In most previous studies on TE based on dynamic traffic grooming, the objectives were to minimize the rejection probability by respecting the constraints of the optical node architecture, but without considering service differentiation. In practice, some high-priority (HP) connections can instead be characterized by specific constraints on the maximum tolerable end-to-end delay and packet-loss ratio. The proposed solution consists of a distributed two-stage scheme: each time a new request arrives, an on-line dynamic grooming scheme finds a route which fulfills the QoS requirements. If a HP request is blocked at the ingress router, a preemption algorithm is executed locally in order to create room for this traffic. The proposed preemption mechanism minimizes the network disruption, both in term of number of rerouted low-priority connections and new set-up lightpaths, and the signaling complexity. Extensive simulation experiments are performed to demonstrate the efficiency of our scheme

Churn, Baby, Churn: Strategic Dynamics Among Dominant and Fringe Firms in a Segmented Industry

This paper integrates and extends the literatures on industry evolution and dominant firms to develop a dynamic theory of dominant and fringe competitive interaction in a segmented industry. It argues that a dominant firm, seeing contraction of growth in its current segment(s), enters new segments in which it can exploit its technological strengths, but that are sufficiently distant to avoid cannibalization. The dominant firm acts as a low-cost Stackelberg leader, driving down prices and triggering a sales takeoff in the new segment. We identify a “churn” effect associated with dominant firm entry: fringe firms that precede the dominant firm into the segment tend to exit the segment, while new fringe firms enter, causing a net increase in the number of firms in the segment. As the segment matures and sales decline in the segment, the process repeats itself. We examine the predictions of the theory with a study of price, quantity, entry, and exit across 24 product classes in the desktop laser printer industry from 1984 to 1996. Using descriptive statistics, hazard rate models, and panel data methods, we find empirical support for the theoretical predictions

Health promotion interventions in social economy companies in Flanders (Belgium)

BACKGROUND: Disadvantaged groups are often not reached by mainstream health promotion interventions. Implementing health promotion (HP) interventions in social economy companies, can be an opportunity to reach those people. The implementation of these interventions in social economy companies was studied. Factors that could be related to the implementation of HP and being supportive towards implementation in the future, were investigated. METHODS: An online, quantitative survey was sent to all 148 sheltered and social workshops in Flanders. In the questionnaire, the status of HP interventions and characteristics of the workshop were explored. Personal factors (such as attitudes towards HP, behavioural control, social norms and moral responsibility) were asked to the person responsible for implementation of HP interventions. Univariate and multivariate logistic regressions were performed. RESULTS: Respondents of 88 workshops completed the questionnaire. Almost 60 % of the workshops implemented environmental or policy interventions. Having a positive attitude towards HP, being more morally responsible, and having the subjective norm that employees are positive towards health promotion at work, were related to being more supportive towards the implementation of HP in the univariate analyses. Only attitude stayed significantly related to being more supportive towards the implementation of HP in the multivariate analyses. CONCLUSIONS: Sheltered and social workshops are open to HP interventions, but more can be done to optimize the implementation. To persuade persons responsible for the implementation of HP to invest more in HP, changing attitudes concerning the benefits of health promotion for the employee and the company, is an important strategy