Carbon-Oriented Electricity Balancing Market for Dispatchable Generators and Flexible Loads

The high renewables penetration results in increased imbalance volumes and balancing actions due to system stability requirements. The balancing market (BM) primarily turns down renewable generation and turns up traditional carbon-intensive generation in response to real-time energy imbalance. Existing dual-stage market mechanisms conflict with the carbon reduction trajectory by implementing balancing actions regardless of their carbon footprint. This paper proposes a novel carbon-oriented BM model to coordinate the environmental targets in the dayahead (DA) and real-time BMs. The emissions of dispatchable generators and flexible loads are distinguished by their operation modes and flexibility types, respectively. Carbon signals are incorporated into their bid&amp;#x002F;offer prices through the proposed carbon emission flow (CEF) model. By integrating these carbon incentives, the dual-stage market model is formulated to minimize economic and environmental costs. Simulation results demonstrate that, overall, although the proposed BM mechanism results in an increased cost of balancing services (159.10 m&amp;#x00A3;), there is a concurrent larger drop in carbon costs (294.14 m&amp;#x00A3;), resulting in a reduction in total cost. It enables system operators to incentivize decarbonized energy resources in DA scheduling and real-time balancing actions.</p

The views of general practitioners and practice nurses towards the barriers and facilitators of proactive, internet-based chlamydia screening for reaching young heterosexual men

Background: Chlamydia trachomatis is a common bacterial sexually transmitted infection (STI), which disproportionately affects young people under 25 years. Commonly, more women are offered screening than men. This study obtained the views of general practitioners and practice nurses towards Internet-based screening and assessed levels of support for the development of proactive screening targeting young heterosexual men via the Internet. Methods: Semi-structured telephone interviews with 10 general practitioners and 8 practice nurses, across Central Scotland. Topics covered: experience of screening heterosexual men for chlamydia, views on the use of the Internet as a way to reach young men for chlamydia screening, beliefs about the potential barriers and facilitators to Internet-based screening. Transcripts from audio recordings were analysed with Framework Analysis, using QSR NVivo10. Results: Experiences of chlamydia screening were almost exclusively with women, driven by the nature of consultations and ease of raising sexual health issues with female patients; few practice nurses reported seeing men during consultations. All participants spoke in favour of Internet-based screening for young men. Participants reported ease of access and convenience as potential facilitators of an Internet-based approach but anonymity and confidentiality could be potential barriers and facilitators to the success of an Internet approach to screening. Concerns over practical issues as well as those pertaining to gender and socio-cultural issues were raised. Conclusions: Awareness of key barriers and facilitators, such as confidentiality, practicality and socio-cultural influences, will inform the development of an Internet-based approach to screening. However, this approach may have its limits in terms of being able to tackle wider social and cultural barriers, along with shifts in young people's and health professionals' attitudes towards screening. Nevertheless, employing innovative efforts as part of a multi-faceted approach is required to ensure effective interventions reach the policy agenda

Mutability and Importance of a Hypermutable Cell Subpopulation that Produces Stress-Induced Mutants in Escherichia coli

In bacterial, yeast, and human cells, stress-induced mutation mechanisms are induced in growth-limiting environments and produce non-adaptive and adaptive mutations. These mechanisms may accelerate evolution specifically when cells are maladapted to their environments, i.e., when they are are stressed. One mechanism of stress-induced mutagenesis in Escherichia coli occurs by error-prone DNA double-strand break (DSB) repair. This mechanism was linked previously to a differentiated subpopulation of cells with a transiently elevated mutation rate, a hypermutable cell subpopulation (HMS). The HMS could be important, producing essentially all stress-induced mutants. Alternatively, the HMS was proposed to produce only a minority of stress-induced mutants, i.e., it was proposed to be peripheral. We characterize three aspects of the HMS. First, using improved mutation-detection methods, we estimate the number of mutations per genome of HMS-derived cells and find that it is compatible with fitness after the HMS state. This implies that these mutants are not necessarily an evolutionary dead end, and could contribute to adaptive evolution. Second, we show that stress-induced Lac+ mutants, with and without evidence of descent from the HMS, have similar Lac+ mutation sequences. This provides evidence that HMS-descended and most stress-induced mutants form via a common mechanism. Third, mutation-stimulating DSBs introduced via I-SceI endonuclease in vivo do not promote Lac+ mutation independently of the HMS. This and the previous finding support the hypothesis that the HMS underlies most stress-induced mutants, not just a minority of them, i.e., it is important. We consider a model in which HMS differentiation is controlled by stress responses. Differentiation of an HMS potentially limits the risks of mutagenesis in cell clones

System stress with expanded use of interconnectors in the transition to net-zero

High Voltage Direct Current (HVDC) interconnectors will help enable net-zero energy systems by transmitting renewable energy from where it is abundant to where it is needed. They may also contribute to balancing services, for which there will be increased demand due to the expanded fleet of renewable generation. However, increased and more flexible use of interconnectors, along with changes in generator locations as renewables displace fossil fuels, may lead to congestion on existing AC transmission systems. In this paper, a transmission network model is used to investigate whether power constraints will restrict the use of HVDC interconnectors for flexibility services. A method, demonstrated on the GB transmission network (which is expected to accommodate increased HVDC interconnector and renewable generation capacity as it transitions to net-zero), is presented which explores interconnector activity and identifies which AC network assets limit the capabilities of the HVDC interconnectors and how often. Results showed that the number of constraints met on the GB network, when the interconnectors were operating at all combinations of full import or full export, reduces in future years. Therefore, the current GB transmission network is suitable for effective use of the planned increased number of interconnectors.</p

The influence of nominal stress on wear factors of carbon fibre–reinforced polyetheretherketone (PEEK-OPTIMA ®

Carbon fibre–reinforced polyetheretherketone is an attractive alternative to ultra-high-molecular-weight polyethylene in artificial joints, but little has been published on the influence of stress on the wear factor. We know that in ultra-high-molecular-weight polyethylene, the wear factor reduces as the normal stress increases, which is counter-intuitive but very helpful in the case of non-conforming contacts. In this study, carbon fibre–reinforced polyetheretherketone (PEEK-OPTIMA® Wear Performance) has been investigated in a pin-on-plate machine under steady loads and under stresses typical of hip and knee joints. At stresses below about 6 MPa, wear factors are between 10 and a 100 times lower than for ultra-high-molecular-weight polyethylene but at higher stresses the wear factors increase substantially