The measurement method of NO2 with continuous analysers is specified for EU Ambient Air Quality Directive compliance reporting, which provides a consistent methodology and concurrent NO measurements ...(85/203/EEC-NO2). While the established method of measurement of NO2, following conversion of NO2 to NO using a molybdenum-conversion process, has known interference uncertainties (due to conversion of other oxidised nitrogen (NOy) chemicals, the consistency and traceability of compliance measurement is important. This study compared three continuous NO2 analyser instruments: a Thermo-NOx molybdenum convertor chemiluminescence analyser (Model 42C, ThermoFisher Scientific Inc., MA, USA), a photolytic chemiluminescence analyser (T200UP, Teledyne Technologies Inc., San Diego, USA) and a Cavity Attenuated Phase Shift (CAPS) analyser (T500U, Teledyne Technologies Inc., CA, USA). The instruments were run for over a year at the Auchencorth Moss long-term peatland monitoring site (Southeast Scotland) which is a low NOx atmosphere away from sources. NOy and NHx chemicals were also measured concurrently. This study concludes that there is a strong artefact in molybdenum catalyst chemiluminescent instruments as a result of unselective catalysis of airborne NOy compounds that causes an overestimate of NO2 measured in the atmosphere. The observed artefact in concentration measurements is likely to be observed at the entire UK scale as almost the entirety of the rural air network relies on molybdenum catalyst instruments. We therefore recommend that molybdenum catalyst instruments should be phased out and replaced in air quality monitoring networks with molecule specific (spectroscopy) instrumentation (equivalent in cost, such as those described in this study) that do not suffer from the same measurement artefacts.
•There is a strong artefact in molybdenum catalyst chemiluminescent instruments.•Unselective catalysis of airborne NOy compounds causes an overestimate of NO2.•The majority of global NO2 monitoring networks will have a measurement artefact.•Molecule specific NO2 analysers do not suffer from this artefact.
This open access book investigates whether and how theoretical findings and insights in contemporary art conservation can be translated into the daily work practices of conservators or, vice versa, ...whether and how the problems and dilemmas encountered in conservation practice can inform broader research questions and projects. For several decades now, the conservation of contemporary art has been a dynamic field of research and reflection. Because of contemporary art’s variable constitution, its care and management calls for a fundamental rethinking of the overall research landscape of museums, heritage institutions, private-sector organizations and universities. At first, this research was primarily pursued by conservation professionals working in or with museums and other heritage organizations, but increasingly academic researchers and universities became involved, for instance through collaborative projects. This book is the result of such collaboration. It sets out to bridge the “gap” between theory and practice by investigating conservation practices as a form of reflection and reflection as a form of practice.
If the virus spreads further throughout our communities, and authorities ask people to limit social contact and self-isolate, cooperation with these necessary measures will play a crucial role in ...minimising COVID-19's spread and protecting the most vulnerable among us. Teams of infectious disease, public health and primary care experts are advising the Government on the best way to deal with this threat.
The close relationship between the theory of fixed points and the theory of coincidences of maps is well known. This presentation is aimed at recording one of the less well documented approaches to ...fixed point theory as extended to the more general situation of coincidences. The approach referred to is that by way of the Universal Covering Spaces. The existing theory of coincidences is geometrically well realised in this setting and after some consideration, the necessary extensions and generalizations of the techniques as utilized in fixed point theory lead to an appealing conceptual notion of "essentiality of coincidence classes". Many hints have been made in the literature (see 1 and "On the sharpness of the Δ₂ and Δ₁ Nielsen Numbers" by Robin Brooks, J.Reine Angew. Math. 259, (1973), 101-108.) that lifts of mappings and the theory of fibres and related topics lend themselves to coincidence theory. It is the intention of this presentation to follow some of the basic properties through this approach and to show, wherever it is thought desirable, the ties between this and two of the existing approaches - for example, in the definition of the Nielsen Number, which is fundamental to both fixed point theory and coincidence theory.
Policy reforms and structural adjustment programs in Sahelian countries have eliminated many public agricultural support programs, creating a vacuum that has not yet been filled by the private ...sector. Sahelian farmers thus face more difficult access to inputs and higher input costs. Input use has stagnated or declined, yet higher population and less land for expansion of cultivation make it vital to increase the productivity of already cultivated land through adoption of intensive agricultural production techniques. While partial intensification is becoming common, too little investment is occurring in inputs and land improvements that maintain soil fertility, control erosion, and improve water availability. Partial intensification therefore risks being an unsustainable strategy. Higher and more sustainable productivity growth requires significantly increased use of chemical and organic fertilizer, improved seeds, bunds, and animal traction. The dilemma is how to ensure that such investments are financially and economically profitable and affordable in terms of government budgets. It is crucial to: (1) improve input access and reduce the unit cost of inputs to farmers through infrastructure investment; (2) increase the productivity of fertilizer and improved seed by encouraging complementary farm-level investments; (3) improve the coordination of input and output marketing systems, and improve incentives for private sector involvement; (4) improve farmers' ability to buy inputs using credit and non-farm income; (5) reduce the financial risks of purchased input use through integrated input/output markets and innovative credit schemes; and (6) evaluate the net economic benefits of selected agricultural support programs, including input subsidies.
The paper examines the determinants of household purchases of already-processed millet, sorghum, and maize in urban Mali. The results show that these purchases (as well as those of rice) rise with ...the opportunity cost of women's time as well as with household income. The results for the two most important coarse grains in the Sahel (millet and sorghum) differ widely, however; while raw millet and processed millet are similarly affected by income and women's opportunity cost of time, the results for raw sorghum are the opposite of those for processed sorghum. Whereas improving sorghum processing will increase total sorghum demand as urban incomes rise, the same cannot be said for millet. Three sets of subsector policies would increase demand for processed coarse grains: (1) promoting access to and use of abrasive-disk dehullers at the semi-wholesale level; (2) promoting improvements in the quality and cleanliness of the grain available to dehullers, and instituting grading by grain quality in the marketing system; (3) increasing consumer information about possible savings realized on purchases of dehulled cereals, via for example, the Malian Market Information System (SIM).
This article uses household survey data from Bamako, Mali, to address three questions, important in the policy debate concerning the determinants of the substitution from coarse grains to rice in ...West African diets, and policy options. The questions are: (1) what are the relative costs of rice and coarse grain-based dishes, with and without complementary sauce costs? (2) What are the shares in total cost of individual processing and preparation stages? (3) Are pre-processed coarse grains (e.g. dehulled grain or flour) cheaper to consume than coarse grains processed in the household? Contrary to prevailing opinion, the paper shows that despite higher processing costs, coarse grain-based dishes are cheaper than rice-based dishes. The main contributory factors to the higher cost of rice-based dishes are sauce cost, cereal cost and preparation (cooking and sauce preparation) time. The result holds true over a wide range of rice and coarse grain prices, and opportunity costs of women's time, suggesting that the finding applies more generally to the urban Sahel and not just Bamako. Moreover, coarse grain-based dishes need not take longer to process and prepare than rice-based dishes if the dehulling step is mechanized. However, pre-processed coarse grains are not competitive with household processing given present technology and opportunity costs of women's time. Nor will coarse grains be able to retain the extent of their cost advantage over rice as incomes and labor opportunity costs rise without improvements in the efficiency of processing services.
PDF