110830 research outputs found
Sort by
Characterising water properties of perfluorinated sulfonic acid membranes using terahertz time-domain spectroscopy
Full text linkPerfluorinated sulfonic acid ionomers (PFSAs) are synthetic polymers used in electrochemical devices such as fuel cells and electrolysers due to their low operating temperatures, high proton conductivity, chemical/mechanical stability and low reactant crossover. Membrane performance is highly dependent upon water content due to the role of water in proton conduction mechanisms such as the Grotthus hopping and vehicle mechanisms. Terahertz timedomain spectroscopy (THz-TDS) is an emerging technique which has previously shown sensitivity to the reorientation dynamics of water molecules within thick Nafion 117 PFSAs at a hydrated state and ambient conditions. It is challenging to make comparisons and utilise this information due to the different environments in which additional sample measurements, complimentary experiments and other techniques are performed. This approach is also limited to thicker membranes and not suitable to more industrially relevant thin membranes. This work therefore aims to address these issues and asses the techniques applicability for studying additional water properties within PFSAs. Therefore, in this work a humidity-controlled environment was developed in which THz-TDS measurements could be acquired to extract both water uptake and water states. This work found that the relative proportion of bulk water which is associated with proton conduction increases with higher water contents and relative humidities. Differences in these states between membranes have been observed providing additional material insight which could be utilised for membrane optimisation. Utilising this controlled environment, this work also demonstrates that THz-TDS has the ability to contactlessly study transient water diffusivity and hygral swelling of PFSAs
An integrated data-driven-simulation-optimization model : insights into controlling invasive plants in China
Full text linkThe rapid spread of invasive plants such as Spartina alterniflora has emerged as a major ecological and economic threats to coastal wetlands, while existing management strategies often fail to adapt to dynamic invasion processes and limited financial resources. To address this challenge, this study develops a novel data-driven-simulation-optimization (DDSO) framework that enables dynamic and spatially explicit management of biological invasions. The core innovation lies in coupling data-driven ecological parameterization based on multi-source observations with a simulation model that captures life-cycle transitions and spatial dispersal, and a mixed-integer optimization module that allocates control budgets and intervention intensities across space and time. By integrating heterogeneous environmental, biological, and management data, the framework constructs time-varying ecological parameters that reflect evolving invasion conditions and underlying ecological processes. The optimization component then generates cost-effective intervention schedules under fixed budget constraints. Comparative evaluation against system dynamics (SD) and simulation-optimization (SO) models shows that DDSO outperforms conventional approaches not only in budget efficiency, but also by revealing counterintuitive management logics: management effectiveness hinges more on the presence of a coordinated optimization framework than on investment scale, and economically efficient strategies inherently favor highly uneven spatial resource allocation. These mechanism-level insights underscore the importance of early intervention and cross-regional coordination, establishing DDSO as a policy-relevant framework for adaptive invasive species management
Time-Varying Capacity Planning for Designing Large-Scale Homeless Care Systems
Full text linkMany people in communities around the world are facing homelessness due to housing shortages. The San Francisco Bay Area has struggled to provide housing for thousands of people who are unsheltered. Permanent housing is the ideal solution for most people entering the system, but temporary shelter is also critical. Investment in housing and shelter is paramount to providing a long-term solution to serve the current and future homeless population. We construct a queueing model for tracking the flow of single adults through shelter and housing based on Alameda County’s coordinated entry system. In contrast to routing or allocation policies, we optimize the system through increasing shelter and housing server capacities. We formulate optimization problems to reduce the size of the unsheltered population given cost constraints by varying investment in housing and shelter over time. Additionally, we impose policy-based shape constraints to reflect the time-dependence and feasibility constraints associated with planning decisions. We thus show how resources can be allocated between housing and shelter over time. While this joint optimization approach can be used to analyze homeless populations outside of Alameda County, it also can be broadly applied to capacity investment decisions for tandem queueing systems, for example, in healthcare settings
Global marine fish trade networks track international pathways of nutrients and contaminants
No full textMarine fish trade globalizes nutrients and contaminants. Using trade data, human demographic information, and nutrient and contaminant exposure data, the estimated direct consumption of traded fish from Northeast Atlantic Ocean (NEAO) catches varied among 155 importer countries/regions. The associated trade pathways globalised high amounts of important nutrients including iodine, selenium, and eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) and contributed greatly to annual domestic EPA+DHA requirements for small-population importers (e.g., Lithuania: 62.8%) but not for high-population importers (e.g., Chinese mainland). Traded amounts of mercury, dioxin, and dioxin-like polychlorinated biphenyls (dl-PCBs) from the NEAO fish were low, and associated pathway contributions to total domestic mercury exposures wer
A strategic roadmap for implementing superconductivity towards zero-emission transport
Full text linkSuperconductivity is an essential technology for reducing carbon emissions and electrifying the transportation sector. Its unique ability to provide higher power density and greater efficiency sets it apart from other technologies. This document outlines a plan for integrating superconducting technology into the transportation sector, identifying major challenges and interim steps to be taken to overcome them. Implementing this plan and securing public and private funds will help transition the transportation sector towards zero-emission aircraft, high-capacity efficient shipping, and widespread use of a superconductivity-liquid hydrogen energy platform for transportation
Plant uptake of available N from different layers varies among species in an alpine meadow of permafrost regions on the Qinghai-Tibetan Plateau
Full text linkThe N uptake of five common species from different soil depths in alpine meadow was investigated. Plants primarily took up more than 75% from the top 15 cm. The dominant sedge species and rare forbs species could take up N from soil as deep as 70 cm. The N uptake capacity is unrelated with the relative coverage. The uptake of permafrost thaw released nitrogen (N) could benefit plant growth and change vegetation community composition in a warming climate in cold regions. However, the capacity of co-existing species to take up different forms of available N beyond the root zone remains largely unknown in permafrost areas with a deep active layer. In situ15NH4Cl, K15NO3 and C2H5NO2 (glycine) labelling were conducted up to 70 cm depth for five species. Averaged across the five species, the summed 15N recovery rate of the three tracers was 10.71% ± 10.69%, 1.69% ± 2.51%, 1.54% ± 4.16% and 0.7% ± 2.23% at 0–15, 15–30, 30–50 and 50–70 cm, respectively. Kobresia humilis had the largest N uptake diversity. The NO3−-N recovered from 30–70 cm for K. humilis and Saussurea japonica was much higher than other species, accounting for 23% and 13% of the total N recovered at 0–70 cm. Root surface area was positively related to the recovery rate of inorganic N at soil below 15 cm whereas a species’ N requirement negatively to the N recovery at 0–15 cm. The relative cover of a species in a community was negatively related to a species’ N requirement but showed no relationship with the N recovery rate or N uptake diversity. Plant communitycomposition may not be affected by vertical N uptake patterns of co-existing species. Species that can take up N from deep soil layers may gain competitive advantages, thereby altering the plant community structure in a warm climate in the future
Measurements of differential cross-sections of WbWb production in the dilepton channel in pp collisions at s = 13 TeV using the ATLAS detector
No full textAt the Large Hadron Collider, the WbWb final state is expected to be dominated by tt¯ production with a contribution from single-top processes. Differential cross-sections for WbWb production in the dilepton decay channel are measured at the particle level as a function of various kinematic variables. The analysis is based on data from proton-proton collisions at a centre-of-mass energy of s=13 TeV, recorded by the ATLAS detector at the Large Hadron Collider over the period from 2015 to 2018, corresponding to an integrated luminosity of 140 fb−1. Measurements are performed within the fiducial phase-space defined by the presence of two b-jets and one electron and one muon of opposite charges. The differential cross-sections are corrected for detector effects and unfolded to the particle level. Results are compared with predictions from Monte Carlo event generators at next-to-leading order in perturbative quantum chromodynamics; overall the measurements are in reasonable agreement with several generator setups, although no single prediction is able to describe all measured distributions simultaneously. These measurements provide valuable constraints on the modelling of WbWb production and the interference between doubly resonant and singly resonant WbWb production
Futurs mondes de la santé: Méthodes spéculatives, humanités médicales, et cultures françaises et francophones
Full text linkSocial mobility is a joke : Working-class women and British TV comedy on ‘the social floor’
No full textThis article examines a range of recent autosociobiographical representations of and by working-class women in the contemporary UK, focusing on Rain Dogs, Chewing Gum and Alma’s Not Normal. It argues that what unites these different representations – all of which are TV comedy-dramas, some with connecting iterations as memoir and play – is a vigorous critique and rejection of the neoliberal meritocratic dream. These representations show that the idea of a level playing field in which working hard to activate talent results in success is simply not a possibility for most working-class women: upwards social mobility is a joke. Yet crucially, this situation is not simply portrayed as a thwarted tragedy of the downtrodden, or as poverty porn in the tradition of reality TV. Instead, through life-affirming exuberant comedy, they show how the wider socio-political landscape is unjust while energetically refusing to accept its limits or internalise its stigma: they ‘reject respectability’. Unlike the majority of autosociobiographies, these representations primarily use a comedic tone. Their focus is not on ‘escape’, ‘transcendence’ or the aspiration for a middle-class life, but on the complexities of working-class lives as lived in context, and on critiquing institutional structures. They do value collective community support and crave the security of putting a ‘social floor’ on their circumstances, of not having to constantly worry about losing everything. Considering why the televisual is a useful vehicle for these narratives, the article asks: what do these women’s exuberant rejections of neoliberal meritocracy and bourgeois standards of judgement indicate about the wider cultural, social and political context, or current conjuncture