On the pathwise approximation of stochastic differential equations

We consider one-step methods for integrating stochastic differential equations and prove pathwise convergence using ideas from rough path theory. In contrast to alternative theories of pathwise convergence, no knowledge is required of convergence in pth mean and the analysis starts from a pathwise bound on the sum of the truncation errors. We show how the theory is applied to the Euler-Maruyama method with fixed and adaptive time-stepping strategies. The assumption on the truncation errors suggests an error-control strategy and we implement this as an adaptive time-stepping Euler-Maruyama method using bounded diffusions. We prove the adaptive method converges and show some computational experiments.Comment: 21 page

The cloning and expression of amylolytic genes in "Escherichia coli" and their role in starch utilization

The structural genes for the K.pneumoniae maltohexaose (G6)-producing amylase, the K.pneumoniae pullulanase and the B.licheniformis α-amylase were cloned and expressed in E.coli. Plasmids carrying the G6-producing amylase, conferred starch utilization on E.coli, but this growth was much slower than growth on glucose. On SDS-PAGE gels, the putative G6-producing amylase had an Mᵣ 67,000. Strains carrying the pullulanase plasmid (pPT14) were able to utilize pullulan as their sole carbon source. On SDS-PAGE the cloned pullulanase comigrates with purified pullulanase (Mᵣ 120,000+). Certain insertions and deletions in the cloned pullulanase fragment reduce growth rate on pullulan. The phenotypes expressed by malB strains and mutants which reduce plasmid copy number suggested that at least one other gene product was required in addition to the pullulanase gene, for effective utilization of pullulan by E.coli. A possible candidate for one of these extra gene products was a protein (Mᵣ 94,000) which was expressed in maxicells. Possible mechanisms of pullulan utilization are discussed. Strains carrying the B.licheniformis α-amylase plasmids (pPT80, pPT81, pPT8Ti and pPX2) could all grow on starch. A copy number of approximately 50 was required for efficient growth (i.e. as good as growth on glucose). When expressed in E.coli the α-amylase is found almost entirely in the periplasmic space. The evidence suggests that the α-amylase is poorly expressed in E.coli and only relatively small amounts of enzyme are required for starch utilization. A model for starch utilization in E.coli is discussed. The whole of the 3.466 kb insert carrying the B.licheniformis α-amylase gene was sequenced. The insert had three open reading frames, only one of which formed a complete gene. This open reading frame corresponded to the B.licheniformis α-amylase gene, coded for a protein of Mᵣ 58,492 and had a 29 amino-acid putative signal sequence. The protein was very homologous to both the B.amyloliquefaciens and B.stearothermophilus α-amylases. The B.licheniformis α-amylase was put under tac promoter control on a high copy number plasmid. Induction with IPTG caused lethality. Uninduced α-amylase levels were sufficient to allow E.coli to grow on starch. The mRNA start points for both the wildtype gene and the tac construct were determined. The effect of removing the major part of the α-amylase signal sequence was studied. This was achieved by a combination of site-directed and linker mutagenesis of the α-amylase DNA. This construct was poorly expressed in E.coli and did not exhibit a lethal phenotype

A rubbish idea : how blockchains could tackle the world’s waste problem

Waste litters our oceans, beaches and wider environment, making it one of the pressing issues of our times. Blockchains are virtual ledgers on which data can be permanently stored. They are a public record, so they are very transparent and accountable. This post aims to set out how blockchains may be used as part of the waste management toolkit

Blockchain Technology for Sustainable Waste Management

The global waste and resource crises necessitate and give great impetus for better and more sustainable management of waste. Increasingly, resource and waste streams that once were sent to landfill or incinerated are now reused, recycled, or recovered. Yet, while many laws and policies have been adopted for this very purpose, a number of recurrent challenges persist across interventions seeking to further facilitate the necessary, widespread transitions to sustainable waste management. This perspective article explores the suitability of blockchain technology in overcoming these challenges. In particular, we discuss the opportunities and challenges for blockchain in (1) offering clarity in property rights of products and wastes, (2) supporting law and policy goals by incentivizing sustainable waste management, and (3) maintaining anonymity and privacy for institutions and individuals

Blockchain Technology for Governance of Plastic Waste Management: Where Are We?

Blockchain technology is emerging as a plausible disruptor of waste management practices that influence the governance of plastics. The interest among the waste management community in the potential and fundamental changes to complex resource management associated with blockchain adoption parallels recent research in other sectors, such as finance, health, public administration, etc. During any comparable period characterized by a step-change in positive coverage of an early-stage technology, it can be challenging for actors to access a grounded, evidence-based oversight of the current state of practice and make informed decisions about whether or how to adopt blockchain technology. The current absence of such a systematic overview of recent experiences with blockchain initiatives disrupting waste practices not only limits the visibility of these experimental efforts, but also limits the learning that can be shared across waste plastics researcher and practitioner communities. This paper contributes with a current overview of blockchain technology adoption in the waste management sector, giving particular attention to implications for the governance of plastics. Our study draws on both primary interview data and secondary documentation data to map the landscape of current blockchain initiatives in the global waste sector. We identify four areas of blockchain use that are beginning to change waste management practices (payment, recycling and reuse rewards, monitoring and tracking of waste, and smart contracts). We conclude by outlining five areas of significant blockchain uses, implications, and influences of relevance to the development of circular plastic waste governance in both research and practice

Selection of compressible signals from telemetry data

Sensors are deployed in all aspects of modern city infrastructure and generate vast amounts of data. Only subsets of this data, however, are relevant to individual organisations. For example, a local council may collect suspension movement from vehicles to detect pot-holes, but this data is not relevant when assessing traffic flow. Supervised feature selection aims to find the set of signals that best predict a target variable. Typical approaches use either measures of correlation or similarity, as in filter methods, or predictive power in a learned model, as in wrapper methods. In both approaches selected features often have high entropies and are not suitable for compression. This is of particular issue in the automotive domain where fast communication and archival of vehicle telemetry data is likely to be prevalent in the near future, especially with technologies such as V2V and V2X. In this paper, we adapt a popular feature selection filter method to consider the compressibility of signals being selected for use in a predictive model. In particular, we add a compression term to the Minimal Redundancy Maximal Relevance (MRMR) filter and introduce Minimal Redundancy Maximal Relevance And Compression (MRMRAC). Using MRMRAC, we then select features from the Controller Area Network (CAN) and predict each of current instantaneous fuel consumption, engine torque, vehicle speed, and gear position, using a Support Vector Machine (SVM). We show that while performance is slightly lower when compression is considered, the compressibility of the selected features is significantly improved

“I don’t want to look sick skinny”: Perceptions of body image and weight loss in Hispanics living with HIV in South Texas

Objective: Obesity is rising in people with HIV (PLWH) and Hispanics. Both HIV and obesity are associated with cardiovascular disease morbidity and mortality. Our goal is to understand perceptions of body image and lifestyle in Hispanics with HIV to adapt interventions appropriately. Methods: We conducted semi-structured interviews with 22 Hispanic PLWH and 6 providers. Purposive sampling selected patient participants across weights and genders. Interviews were coded and analyzed using grounded theory, comparing perspectives between patients with and without obesity, and patients and providers. Results: Participants felt obesity and diabetes were “normal” in the community. Patients exhibited understanding of healthy diet and lifestyle but felt incapable of maintaining either. Traditionally Hispanic foods were blamed for local obesity prevalence. Five patients equated weight with health and weight loss with illness, and four expressed concerns that weight loss could lead to unintentional disclosure of HIV status. Participants with overweight or obesity expressed awareness of their weight and felt shamed by providers. Providers found weight loss interventions to be ineffective. Conclusion: Interventions in this population must address identified barriers: overweight/obesity as a normative value, lack of self-efficacy, cultural beliefs surrounding food, fear of HIV-associated weight loss and stigma, and provider perspectives on intervention futility

Managing a Safe and Successful Multi-User Spaceport

Encouraged by the creation of the Office of Commercial Space Transportation within the U.S. Federal Aviation Administration (FAA) in 1984 and the Commercial Space Act of 1998, the National Aeronautics and Space Administration (NASA) now relies on an extensive network of support from commercial companies and organizations. At NASA's Kennedy Space Center (KSC), this collaboration opens competitive opportunities for launch providers, including repurposing underutilized Shuttle Program resources, constructing new facilities, and utilizing center services and laboratories. The resulting multi-user spaceport fosters diverse activity, though it engenders risk from hazards associated with various spaceflight processing activities. The KSC Safety & Mission Assurance (S&MA) Directorate, in coordination with the center's Spaceport Integration and Center Planning & Development organizations, has developed a novel approach to protect NASA's workforce, critical assets, and the public from hazardous, space-related activity associated with KSC's multi-user spaceport. For NASA KSC S&MA, the transformation to a multi-user spaceport required implementing methods to foster safe and successful commercial activity while resolving challenges involving: Retirement of the Space Shuttle program; Co-location of multiple NASA programs; Relationships between the NASA programs; Complex relationships between NASA programs and commercial partner operations in exclusive-use facilities; Complex relationships between NASA programs and commercial partner operations in shared-use facilities. NASA KSC S&MA challenges were met with long-term planning and solutions involving cooperation with the Spaceport Integration and Services Directorate. This directorate is responsible for managing active commercial partnerships with customer advocacy and services management, providing a dedicated and consistent level of support to a wide array of commercial operations. This paper explores these solutions, their relevance to the current commercial space industry, and the challenges that continue to drive improvement with a focus on areas of safety management and risk assessment that have been crucial in KSC's evolution into a multi-user spaceport. These solutions may be useful to government entities and private companies looking to partner with the commercial space industry