137 research outputs found
Chemical mechanical polishing of thin film diamond
The demonstration that Nanocrystalline Diamond (NCD) can retain the superior
Young's modulus (1,100 GPa) of single crystal diamond twinned with its ability
to be grown at low temperatures (<450 {\deg}C) has driven a revival into the
growth and applications of NCD thin films. However, owing to the competitive
growth of crystals the resulting film has a roughness that evolves with film
thickness, preventing NCD films from reaching their full potential in devices
where a smooth film is required. To reduce this roughness, films have been
polished using Chemical Mechanical Polishing (CMP). A Logitech Tribo CMP tool
equipped with a polyurethane/polyester polishing cloth and an alkaline
colloidal silica polishing fluid has been used to polish NCD films. The
resulting films have been characterised with Atomic Force Microscopy, Scanning
Electron Microscopy and X-ray Photoelectron Spectroscopy. Root mean square
roughness values have been reduced from 18.3 nm to 1.7 nm over 25 {\mu}m,
with roughness values as low as 0.42 nm over ~ 0.25 {\mu}m. A polishing
mechanism of wet oxidation of the surface, attachment of silica particles and
subsequent shearing away of carbon has also been proposed.Comment: 6 pages, 6 figure
Uncovering the First AGN Jets with AXIS
Jets powered by AGN in the early Universe () have the potential
to not only define the trajectories of the first-forming massive galaxies but
to enable the accelerated growth of their associated SMBHs. Under typical
assumptions, jets could even rectify observed quasars with light seed formation
scenarios; however, not only are constraints on the parameters of the first
jets lacking, observations of these objects are scarce. Owing to the
significant energy density of the CMB at these epochs capable of quenching
radio emission, observations will require powerful, high angular resolution
X-ray imaging to map and characterize these jets. As such, \textit{AXIS} will
be necessary to understand early SMBH growth and feedback.Comment: 7 Pages, 2 Figures. This White Paper is part of a series commissioned
for the AXIS Probe Concept Mission; additional AXIS White Papers can be found
at the AXIS website (http://axis.astro.umd.edu/) with a mission overview
here: arXiv:2311.0078
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Reconceptualising the relationship between the creative economy and the city: Learning from the financial crisis
This paper uses the financial crisis as an opportunity to examine a number of key questions about the relationship of the creative economy and the city. We argue that weak conceptualisation of the nature of the relationship between the creative economy and the city, as well as a lack of clarity about what the creative economy is, has subverted debates about this important topic. This paper comprises four major sections: the first introduces the field of the creative economy, the second section seeks to clarify what exactly we mean by the term financial crisis; here we highlight the multifaceted character of the financial crisis and is variable impacts across the field of the creative economy. The third part outlines the range and diversity of the actually existing relations between the creative economy and the city. In the fourth section we reflect upon the earlier argument to consider what we can learn about the impacts (actual and expected) of the financial crisis on the creative economy and the city, and additionally to reflect upon what this might indicate about the changing and perhaps transformed relationship between the creative economy and the city in the last quarter century
Plasma Dynamics
Contains reports on four research projects.National Science Foundation (Grant ECS82-13485)University of Maryland (Subcontract A200728)U.S. Air Force - Office of Scientific Research (Grant AFOSR-84-0026B)U.S. Department of Energy (Contract DE-ACO2-78-ET-51013)National Science Foundation (Grant ECS82-13430
Emerging Technologies for the Detection of Rabies Virus: Challenges and Hopes in the 21st Century
The diagnosis of rabies is routinely based on clinical and epidemiological information, especially when exposures are reported in rabies-endemic countries. Diagnostic tests using conventional assays that appear to be negative, even when undertaken late in the disease and despite the clinical diagnosis, have a tendency, at times, to be unreliable. These tests are rarely optimal and entirely dependent on the nature and quality of the sample supplied. In the course of the past three decades, the application of molecular biology has aided in the development of tests that result in a more rapid detection of rabies virus. These tests enable viral strain identification from clinical specimens. Currently, there are a number of molecular tests that can be used to complement conventional tests in rabies diagnosis. Indeed the challenges in the 21st century for the development of rabies diagnostics are not of a technical nature; these tests are available now. The challenges in the 21st century for diagnostic test developers are two-fold: firstly, to achieve internationally accepted validation of a test that will then lead to its acceptance by organisations globally. Secondly, the areas of the world where such tests are needed are mainly in developing regions where financial and logistical barriers prevent their implementation. Although developing countries with a poor healthcare infrastructure recognise that molecular-based diagnostic assays will be unaffordable for routine use, the cost/benefit ratio should still be measured. Adoption of rapid and affordable rabies diagnostic tests for use in developing countries highlights the importance of sharing and transferring technology through laboratory twinning between the developed and the developing countries. Importantly for developing countries, the benefit of molecular methods as tools is the capability for a differential diagnosis of human diseases that present with similar clinical symptoms. Antemortem testing for human rabies is now possible using molecular techniques. These barriers are not insurmountable and it is our expectation that if such tests are accepted and implemented where they are most needed, they will provide substantial improvements for rabies diagnosis and surveillance. The advent of molecular biology and new technological initiatives that combine advances in biology with other disciplines will support the development of techniques capable of high throughput testing with a low turnaround time for rabies diagnosis
Modeling the multi-functionality of African savanna landscapes under global change
Various recent publications have indicated that accelerated global change and its negative impacts on terrestrial ecosystems in Southern Africa urgently demand quantitative assessment and modelling of a range of ecosystem services on which rural communities depend. Information is needed on how these Ecosystem Services (ES) can be enhanced through sustainable land management interventions and enabling policies. Yet, it has also been claimed that, to date, the required system analyses, data and tools to quantify important interactions between biophysical and socio-economic components, their resilience and ability to contribute to livelihood needs do not exist. We disagree, but acknowledge that building an appropriate integrative modelling framework for assessing the multi-functionality of savanna landscapes is challenging. Yet, in this Letter-to-the-Editor, we show that a number of suitable modelling components and required data already exist and can be mobilized and integrated with emerging data and tools to provide answers to problem-driven questions posed by stakeholders on land management and policy issues.German Federal Ministry of Education and Researchhttps://onlinelibrary.wiley.com/journal/1099145xhj2022Zoology and Entomolog
COVID-19: Rapid antigen detection for SARS-CoV-2 by lateral flow assay: A national systematic evaluation of sensitivity and specificity for mass-testing
Background
Lateral flow device (LFD) viral antigen immunoassays have been developed around the world as diagnostic tests for SARS-CoV-2 infection. They have been proposed to deliver an infrastructure-light, cost-economical solution giving results within half an hour.
Methods
LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation from 1st August to 15th December 2020. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces).
Findings
4/64 LFDs so far have desirable performance characteristics (orient Gene, Deepblue, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test). All these LFDs have a viral antigen detection of >90% at 100,000 RNA copies/ml. 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1–6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20–0.48). Viral antigen detection/sensitivity across the sampling cohort when performed by laboratory scientists was 78.8% (156/198, 95% CI 72.4–84.3).
Interpretation
Our results suggest LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission.
Funding
Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research
Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.
BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700
Lawson criterion for ignition exceeded in an inertial fusion experiment
For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion
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