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End date: 2019 × Start date: 2010 × Publisher: Philadelphia, Pa : Taylor & Francis ×

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    Mobility particle size spectrometers: Calibration procedures and measurement uncertainties
    (Philadelphia, Pa : Taylor & Francis, 2017) Wiedensohler, A.; Wiesner, A.; Weinhold, K.; Birmili, W.; Hermann, M.; Merkel, M.; Müller, T.; Pfeifer, S.; Schmidt, A.; Tuch, T.; Velarde, F.; Quincey, P.; Seeger, S.; Nowak, A.
    Mobility particle size spectrometers (MPSS) belong to the essential instruments in aerosol science that determine the particle number size distribution (PNSD) in the submicrometer size range. Following calibration procedures and target uncertainties against standards and reference instruments are suggested for a complete MPSS quality assurance program: (a) calibration of the CPC counting efficiency curve (within 5% for the plateau counting efficiency; within 1 nm for the 50% detection efficiency diameter), (b) sizing calibration of the MPSS, using a certified polystyrene latex (PSL) particle size standard at 203 nm (within 3%), (c) intercomparison of the PNSD of the MPSS (within 10% and 20% of the dN/dlogDP concentration for the particle size range 20–200 and 200–800 nm, respectively), and (d) intercomparison of the integral PNC of the MPSS (within 10%). Furthermore, following measurement uncertainties have been investigated: (a) PSL particle size standards in the range from 100 to 500 nm match within 1% after sizing calibration at 203 nm. (b) Bipolar diffusion chargers based on the radioactive nuclides Kr85, Am241, and Ni63 and a new ionizer based on corona discharge follow the recommended bipolar charge distribution, while soft X-ray-based charges may alter faster than expected. (c) The use of a positive high voltage supply show a 10% better performance than a negative one. (d) The intercomparison of the integral PNC of an MPSS against the total number concentration is still within the target uncertainty at an ambient pressure of approximately 500 hPa. Copyright © 2018 Published with license by American Association for Aerosol Research.
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    Typology of vulnerability of wheat farmers in Northeast Iran and implications for their adaptive capacity
    (Philadelphia, Pa : Taylor & Francis, 2019) Nooghabi, Saeedeh Nazari; Fleskens, Luuk; Sietz, Diana; Azadi, Hossein
    This study is focused on understanding sources and patterns of vulnerability of wheat smallholder farmers in Northeast Iran. We conducted a farm household survey and recorded multiple environmental and socio-economic attributes of 391 wheat smallholder farmers. A Vulnerability Scoping Diagram and Principal Component Analysis served to identify key factors determining wheat farmer's vulnerability. Also, we performed a cluster analysis to classify wheat farmers into three vulnerability types. Although drought affects all types as main environmental stressor, only for Cluster 2 was it the key vulnerability factor. For Clusters 1 and 3 socio-economic vulnerability components prevailed: for farmers categorized in Cluster 1 land consolidation was the main problem, while the current wheat import policy was the key problem for Cluster 3 farmers. Multiple tailored policies are needed that reduce the vulnerability of wheat farmers in all clusters. Supportive government policies should for example focus on avoiding price distortions from wheat imports for Cluster 3, land consolidation for Cluster 1 and collective tackling of pests and weeds for Cluster 2. Simultaneous provision of farm advisory services will benefit farmers of Clusters 1 and 3, while availability of improved seeds (drought-tolerant varieties) and other inputs will lower the environmental vulnerability of all farmers. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.