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108 results on '"van Zyl, P. G."'

3. Modelling new particle formation events in the South African savannah

Author

Gierens, Rosa T, Laakso, Lauri, Mogensen, Ditte, Vakkari, Ville, Beukes, Johan P, Van Zyl, Pieter G, Hakola, Hannele, Guenther, Alex, Pienaar, Jacobus J, and Boy, Michael

Subjects
Climate Action, atmospheric modelling, aerosols, nucleation, boundary layer, savannah, General Science & Technology
Abstract

Africa is one of the less studied continents with respect to atmospheric aerosols. Savannahs are complex dynamic systems sensitive to climate and land-use changes, but the interaction of these systems with the atmosphere is not well understood. Atmospheric particles, called aerosols, affect the climate on regional and global scales, and are an important factor in air quality. In this study, measurements from a relatively clean savannah environment in South Africa were used to model new particle formation and growth. There already are some combined long-term measurements of trace gas concentrations together with aerosol and meteorological variables available, but to our knowledge this is the first detailed simulation that includes all the main processes relevant to particle formation. The results show that both of the particle formation mechanisms investigated overestimated the dependency of the formation rates on sulphuric acid. From the two particle formation mechanisms tested in this work, the approach that included low volatile organic compounds to the particle formation process was more accurate in describing the nucleation events than the approach that did not. To obtain a reliable estimate of aerosol concentration in simulations for larger scales, nucleation mechanisms would need to include organic compounds, at least in southern Africa. This work is the first step in developing a more comprehensive new particle formation model applicable to the unique environment in southern Africa. Such a model will assist in better understanding and predicting new particle formation - knowledge which could ultimately be used to mitigate impacts of climate change and air quality. © 2014. The Authors.

Published
2014

13. A Study of Single-Gender Grouping for Sixth Grade Math as a Strategy for Improving Student Achievement

Author

Van Zyl, Douglas G.

Abstract

Purpose of the study. The purpose of this study was to examine single-gender groupings for sixth grade mathematics classes as a strategy to improve student achievement. The method of research was quantitative, with MAP mathematics test data being used to determine if any relationship exists between the strategy and student achievement. Findings. From this study a firm conclusion about the value of single-gender classes is problematic. While the experimental group appeared to make a difference in the basic statistical analyses, the fact that the findings were not significant when a proxy measure for poverty (free and reduced lunch) and gender are both added to the statistical formulae raise substantial concerns about the value of single-gender classes. Further research is needed to better clarify the true value of single-gender classes compared to mixed-gender issues. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

Published
2011

18. Chemical composition of rain at a regional site on the South African Highveld.

Author

Kok, L., van Zyl, P. G., Beukes, J. P., Swartz, J.-S., Burger, R. P., Ellis, Suria, Josipovic, M., Vakkari, V., Laakso, L., and Kulmala, M.

Subjects
*BIOMASS burning, *RAINWATER, *DATA quality, *POLLUTANTS, *SULFUR
Abstract

Relatively limited data have been published on the chemical composition of wet deposition for South Africa, which is considered an important source region for atmospheric pollutants. Concentrations and wet deposition fluxes of ionic species determined in rain samples collected from December 2014 to April 2018 at a regional site, Welgegund, are presented, and contextualised by wet deposition composition in the northeastern interior of South Africa. 89% of rain samples collected during the sampling period complied with the data quality objectives of the World Meteorological Organisation. The total ionic concentration of rainwater at Welgegund was similar to that at two regional sites located within proximity of industrial activities. The pH of rainwater (4.80) was comparable to that determined at two rural background sites, which indicated increased neutralisation. Similarly to the other sites located in the South African interior, SO4 2- was the most abundant species in rain, with concentrations thereof in the same order as SO4 2- levels determined at the two industrially influenced sites. Lower sulphur and nitrogen fluxes at Welgegund were attributed to lower average annual rainfall. The anthropogenic (industrial) source group had the largest contribution to wet deposition chemical composition, which signified the influence of major source regions in the South African interior that impact Welgegund. Relatively large contributions were also calculated from marine and crustal sources. The influence of agricultural activities was also evident, while biomass burning had the lowest contribution due to open biomass burning occurring mainly during the dry season. [ABSTRACT FROM AUTHOR]

Published
2021
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19. Carbon balance of a grazed savanna grassland ecosystem in South Africa

Author

University of Helsinki, Department of Physics, University of Helsinki, Department of Geosciences and Geography, Räsänen, M., Aurela, M., Vakkari, V., Beukes, J. P., Tuovinen, J.-P., Van Zyl, P. G., Josipovic, M., Venter, A. D., Jaars, K., Siebert, S. J., Laurila, T., Rinne, J., Laakso, L., University of Helsinki, Department of Physics, University of Helsinki, Department of Geosciences and Geography, Räsänen, M., Aurela, M., Vakkari, V., Beukes, J. P., Tuovinen, J.-P., Van Zyl, P. G., Josipovic, M., Venter, A. D., Jaars, K., Siebert, S. J., Laurila, T., Rinne, J., and Laakso, L.

Abstract

Tropical savannas and grasslands are estimated to contribute significantly to the total primary production of all terrestrial vegetation. Large parts of African savannas and grasslands are used for agriculture and cattle grazing, but the carbon flux data available from these areas are limited. This study explores carbon dioxide fluxes measured with the eddy covariance method for 3 years at a grazed savanna grassland in Welgegund, South Africa. The tree cover around the measurement site, grazed by cattle and sheep, was around 15 %. The night-time respiration was not significantly dependent on either soil moisture or soil temperature on a weekly temporal scale, whereas on an annual timescale higher respiration rates were observed when soil temperatures were higher. The carbon dioxide balances of the years 2010-2011, 2011-2012 and 2012-2013 were 85 +/- 16, 67 +/- 20 and 139 +/- 13 gCm(-2) yr(-1), respectively. The yearly variation was largely determined by the changes in the early wet season fluxes (September to November) and in the mid-growing season fluxes (December to January). Early rainfall enhanced the respiratory capacity of the ecosystem throughout the year, whereas during the mid-growing season high rainfall resulted in high carbon uptake.

Published
2017

22. Evaluation of the accuracy of visual glucose estimates by healthcare providers and patients at Kalafong Hospital, City of Tshwane, South Africa

Author

Mhishi, Simbarashe B and van Zyl, Danie G

Abstract

Background:A patient-centred approach with self-monitoring of blood glucose (SMBG) has emerged as the preferred approach in monitoring and managing blood glucose. The success of SMBG in diabetes treatment and management relies heavily on the accurate and reproducible measurement of blood glucose values.Aim:To evaluate whether patients and healthcare professionals can accurately estimate blood glucose using photometric strips, by visually matching them to colorimetric charts.Methods:A cross-sectional study design was used with participants enrolled from patients and healthcare providers attending and working at the Diabetes Clinic of Kalafong Provincial Tertiary Hospital (KPTH). A convenience sample of 144 patients and 10 healthcare professionals was enrolled.Results:Limits of agreement of patient and healthcare professional visual estimates were 11.1 to 10.4 mmol/l and 6.7 to 5.7 mmol/l, respectively. The mean difference for estimates by healthcare professionals was 0.8 mmol/l (95% CI 1.30–0.31 mmol/l) while patient estimates had a mean difference of 0.4 mmol/l (95% CI 1.2−0.5 mmol/l).Conclusions:The study noted that visual colour matching was inexact and generally would overestimate blood glucose. Healthcare professionals gave visual estimates that were more accurate in comparison with patients.

Published
2020
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24. PollyNET: a global network of automated Raman-polarization lidars for continuous aerosol profiling

Author

Baars, H., primary, Kanitz, T., additional, Engelmann, R., additional, Althausen, D., additional, Heese, B., additional, Komppula, M., additional, Preißler, J., additional, Tesche, M., additional, Ansmann, A., additional, Wandinger, U., additional, Lim, J.-H., additional, Ahn, J. Y., additional, Stachlewska, I. S., additional, Amiridis, V., additional, Marinou, E., additional, Seifert, P., additional, Hofer, J., additional, Skupin, A., additional, Schneider, F., additional, Bohlmann, S., additional, Foth, A., additional, Bley, S., additional, Pfüller, A., additional, Giannakaki, E., additional, Lihavainen, H., additional, Viisanen, Y., additional, Hooda, R. K., additional, Pereira, S., additional, Bortoli, D., additional, Wagner, F., additional, Mattis, I., additional, Janicka, L., additional, Markowicz, K. M., additional, Achtert, P., additional, Artaxo, P., additional, Pauliquevis, T., additional, Souza, R. A. F., additional, Sharma, V. P., additional, van Zyl, P. G., additional, Beukes, J. P., additional, Sun, J. Y., additional, Rohwer, E. G., additional, Deng, R., additional, Mamouri, R. E., additional, and Zamorano, F., additional

Published
2015
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27. The impact of residential combustion emissions on atmospheric aerosol, human health and climate

Author

Butt, E. W., primary, Rap, A., additional, Schmidt, A., additional, Scott, C. E., additional, Pringle, K. J., additional, Reddington, C. L., additional, Richards, N. A. D., additional, Woodhouse, M. T., additional, Ramirez-Villegas, J., additional, Yang, H., additional, Vakkari, V., additional, Stone, E. A., additional, Rupakheti, M., additional, Praveen, P. S., additional, van Zyl, P. G., additional, Beukes, J. P., additional, Josipovic, M., additional, Mitchell, E. J. S., additional, Sallu, S. M., additional, Forster, P. M., additional, and Spracklen, D. V., additional

Published
2015
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28. Characterization of satellite-based proxies for estimating nucleation mode particles over South Africa

Author

Sundström, A.-M., primary, Nikandrova, A., additional, Atlaskina, K., additional, Nieminen, T., additional, Vakkari, V., additional, Laakso, L., additional, Beukes, J. P., additional, Arola, A., additional, van Zyl, P. G., additional, Josipovic, M., additional, Venter, A. D., additional, Jaars, K., additional, Pienaar, J. J., additional, Piketh, S., additional, Wiedensohler, A., additional, Chiloane, E. K., additional, de Leeuw, G., additional, and Kulmala, M., additional

Published
2015
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29. Aqueous solubility of Cr(VI) compounds in ferrochrome bag filter dust and the implications thereof.

Author

du Preez, S. P., Beukes, J. P., van Dalen, W. P. J., van Zyl, P. G., Paktunc, D., and Loock-Hattingh, M. M.

Subjects
FERROCHROME, HEXAVALENT chromium, CHROMIUM, CHROMIUM iron alloys, WASTE storage
Abstract

The production of ferrochrome (FeCr) is a reducing process. However, it is impossible to completely exclude oxygen from all of the high-temperature production process steps, which may lead to unintentional formation of small amounts of Cr(VI). The majority of Cr(VI) is associated with particles found in the off-gas of the high-temperature processes, which are cleaned by means of venturi scrubbers or bag filter dust (BFD) systems. BFD contains the highest concentration of Cr(VI) of all FeCr wastes. In this study, the solubility of Cr(VI) present in BFD was determined by evaluating four different BFD samples. The results indicate that the currently applied Cr(VI) treatment strategies of the FeCr producer (with process water pH ≤ 9) only effectively extract and treat the water-soluble Cr(VI) compounds, which merely represented approximately 31% of the total Cr(VI) present in the BFD samples evaluated. Extended extraction time, within the afore-mentioned pH range, proved futile in extracting sparingly-soluble and water-insoluble Cr(VI) species, which represented approximately 34% and 35% of the total Cr(VI), respectively. Due to the deficiencies of the current treatment strategies, it is highly likely that sparingly water-soluble Cr(VI) compounds will leach from waste storage facilities (e.g. slimes dams) over time. Therefore, it is critical that improved Cr(VI) treatment strategies be formulated, which should be an important future perspective for FeCr producers and researchers alike. [ABSTRACT FROM AUTHOR]

Published
2017
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30. One year of Raman lidar observations of free tropospheric aerosol layers over South Africa

Author

Giannakaki, E., primary, Pfüller, A., additional, Korhonen, K., additional, Mielonen, T., additional, Laakso, L., additional, Vakkari, V., additional, Baars, H., additional, Engelmann, R., additional, Beukes, J. P., additional, Van Zyl, P. G., additional, Josipovic, M., additional, Tiitta, P., additional, Chiloane, K., additional, Piketh, S., additional, Lihavainen, H., additional, Lehtinen, K. E. J., additional, and Komppula, M., additional

Published
2015
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31. Differences in aerosol absorption Ångström exponents between correction algorithms for a particle soot absorption photometer measured on the South African Highveld

Author

Backman, J., primary, Virkkula, A., additional, Vakkari, V., additional, Beukes, J. P., additional, Van Zyl, P. G., additional, Josipovic, M., additional, Piketh, S., additional, Tiitta, P., additional, Chiloane, K., additional, Petäjä, T., additional, Kulmala, M., additional, and Laakso, L., additional

Published
2014
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33. The AeroCom evaluation and intercomparison of organic aerosol in global models

Author

Tsigaridis, K., primary, Daskalakis, N., additional, Kanakidou, M., additional, Adams, P. J., additional, Artaxo, P., additional, Bahadur, R., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Benedetti, A., additional, Bergman, T., additional, Berntsen, T. K., additional, Beukes, J. P., additional, Bian, H., additional, Carslaw, K. S., additional, Chin, M., additional, Curci, G., additional, Diehl, T., additional, Easter, R. C., additional, Ghan, S. J., additional, Gong, S. L., additional, Hodzic, A., additional, Hoyle, C. R., additional, Iversen, T., additional, Jathar, S., additional, Jimenez, J. L., additional, Kaiser, J. W., additional, Kirkevåg, A., additional, Koch, D., additional, Kokkola, H., additional, Lee, Y. H, additional, Lin, G., additional, Liu, X., additional, Luo, G., additional, Ma, X., additional, Mann, G. W., additional, Mihalopoulos, N., additional, Morcrette, J.-J., additional, Müller, J.-F., additional, Myhre, G., additional, Myriokefalitakis, S., additional, Ng, N. L., additional, O'Donnell, D., additional, Penner, J. E., additional, Pozzoli, L., additional, Pringle, K. J., additional, Russell, L. M., additional, Schulz, M., additional, Sciare, J., additional, Seland, Ø., additional, Shindell, D. T., additional, Sillman, S., additional, Skeie, R. B., additional, Spracklen, D., additional, Stavrakou, T., additional, Steenrod, S. D., additional, Takemura, T., additional, Tiitta, P., additional, Tilmes, S., additional, Tost, H., additional, van Noije, T., additional, van Zyl, P. G., additional, von Salzen, K., additional, Yu, F., additional, Wang, Z., additional, Zaveri, R. A., additional, Zhang, H., additional, Zhang, K., additional, Zhang, Q., additional, and Zhang, X., additional

Published
2014
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34. Characterization of satellite based proxies for estimating nucleation mode particles over South Africa

Author

Sundström, A.-M., primary, Nikandrova, A., additional, Atlaskina, K., additional, Nieminen, T., additional, Vakkari, V., additional, Laakso, L., additional, Beukes, J. P., additional, Arola, A., additional, van Zyl, P. G., additional, Josipovic, M., additional, Venter, A. D., additional, Jaars, K., additional, Pienaar, J. J., additional, Piketh, S., additional, Wiedensohler, A., additional, Chiloane, E. K., additional, de Leeuw, G., additional, and Kulmala, M., additional

Published
2014
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35. Ambient aromatic hydrocarbon measurements at Welgegund, South Africa

Author

Jaars, K., primary, Beukes, J. P., additional, van Zyl, P. G., additional, Venter, A. D., additional, Josipovic, M., additional, Pienaar, J. J., additional, Vakkari, V., additional, Aaltonen, H., additional, Laakso, H., additional, Kulmala, M., additional, Tiitta, P., additional, Guenther, A., additional, Hellén, H., additional, Laakso, L., additional, and Hakola, H., additional

Published
2014
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36. Atmospheric boundary layer top height in South Africa: measurements with lidar and radiosonde compared to three atmospheric models

Author

Korhonen, K., primary, Giannakaki, E., additional, Mielonen, T., additional, Pfüller, A., additional, Laakso, L., additional, Vakkari, V., additional, Baars, H., additional, Engelmann, R., additional, Beukes, J. P., additional, Van Zyl, P. G., additional, Ramandh, A., additional, Ntsangwane, L., additional, Josipovic, M., additional, Tiitta, P., additional, Fourie, G., additional, Ngwana, I., additional, Chiloane, K., additional, and Komppula, M., additional

Published
2014
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37. General overview : European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) - integrating aerosol research from nano to global scales

Author

Kulmala, M., Asmi, A., Lappalainen, H. K., Baltensperger, U., Brenguier, J. -L, Facchini, M. C., Hansson, H. -C, Hov, O., O'Dowd, C. D., Poeschl, U., Wiedensohler, A., Boers, R., Boucher, O., de Leeuw, G., van der Gon, H. A. C. Denier, Feichter, J., Krejci, R., Laj, P., Lihavainen, H., Lohmann, U., McFiggans, G., Mentel, T., Pilinis, C., Riipinen, I., Schulz, M., Stohl, A., Swietlicki, E., Vignati, E., Alves, C., Amann, M., Ammann, M., Arabas, S., Artaxo, P., Baars, H., Beddows, D. C. S., Bergström, Robert, Beukes, J. P., Bilde, M., Burkhart, J. F., Canonaco, F., Clegg, S. L., Coe, H., Crumeyrolle, S., D'Anna, B., Decesari, S., Gilardoni, S., Fischer, M., Fjaeraa, A. M., Fountoukis, C., George, C., Gomes, L., Halloran, P., Hamburger, T., Harrison, R. M., Herrmann, H., Hoffmann, T., Hoose, C., Hu, M., Hyvarinen, A., Horrak, U., Iinuma, Y., Iversen, T., Josipovic, M., Kanakidou, M., Kiendler-Scharr, A., Kirkevag, A., Kiss, G., Klimont, Z., Kolmonen, P., Komppula, M., Kristjansson, J. -E, Laakso, L., Laaksonen, A., Labonnote, L., Lanz, V. A., Lehtinen, K. E. J., Rizzo, L. V., Makkonen, R., Manninen, H. E., McMeeking, G., Merikanto, J., Minikin, A., Mirme, S., Morgan, W. T., Nemitz, E., O'Donnell, D., Panwar, T. S., Pawlowska, H., Petzold, A., Pienaar, J. J., Pio, C., Plass-Duelmer, C., Prevot, A. S. H., Pryor, S., Reddington, C. L., Roberts, G., Rosenfeld, D., Schwarz, J., Seland, O., Sellegri, K., Shen, X. J., Shiraiwa, M., Siebert, H., Sierau, B., Simpson, D., Sun, J. Y., Topping, D., Tunved, P., Vaattovaara, P., Vakkari, V., Veefkind, J. P., Visschedijk, A., Vuollekoski, H., Vuolo, R., Wehner, B., Wildt, J., Woodward, S., Worsnop, D. R., van Zadelhoff, G. -J, Zardini, A. A., Zhang, K., van Zyl, P. G., Kerminen, V. -M, Carslaw, K. S., Pandis, S. N., Kulmala, M., Asmi, A., Lappalainen, H. K., Baltensperger, U., Brenguier, J. -L, Facchini, M. C., Hansson, H. -C, Hov, O., O'Dowd, C. D., Poeschl, U., Wiedensohler, A., Boers, R., Boucher, O., de Leeuw, G., van der Gon, H. A. C. Denier, Feichter, J., Krejci, R., Laj, P., Lihavainen, H., Lohmann, U., McFiggans, G., Mentel, T., Pilinis, C., Riipinen, I., Schulz, M., Stohl, A., Swietlicki, E., Vignati, E., Alves, C., Amann, M., Ammann, M., Arabas, S., Artaxo, P., Baars, H., Beddows, D. C. S., Bergström, Robert, Beukes, J. P., Bilde, M., Burkhart, J. F., Canonaco, F., Clegg, S. L., Coe, H., Crumeyrolle, S., D'Anna, B., Decesari, S., Gilardoni, S., Fischer, M., Fjaeraa, A. M., Fountoukis, C., George, C., Gomes, L., Halloran, P., Hamburger, T., Harrison, R. M., Herrmann, H., Hoffmann, T., Hoose, C., Hu, M., Hyvarinen, A., Horrak, U., Iinuma, Y., Iversen, T., Josipovic, M., Kanakidou, M., Kiendler-Scharr, A., Kirkevag, A., Kiss, G., Klimont, Z., Kolmonen, P., Komppula, M., Kristjansson, J. -E, Laakso, L., Laaksonen, A., Labonnote, L., Lanz, V. A., Lehtinen, K. E. J., Rizzo, L. V., Makkonen, R., Manninen, H. E., McMeeking, G., Merikanto, J., Minikin, A., Mirme, S., Morgan, W. T., Nemitz, E., O'Donnell, D., Panwar, T. S., Pawlowska, H., Petzold, A., Pienaar, J. J., Pio, C., Plass-Duelmer, C., Prevot, A. S. H., Pryor, S., Reddington, C. L., Roberts, G., Rosenfeld, D., Schwarz, J., Seland, O., Sellegri, K., Shen, X. J., Shiraiwa, M., Siebert, H., Sierau, B., Simpson, D., Sun, J. Y., Topping, D., Tunved, P., Vaattovaara, P., Vakkari, V., Veefkind, J. P., Visschedijk, A., Vuollekoski, H., Vuolo, R., Wehner, B., Wildt, J., Woodward, S., Worsnop, D. R., van Zadelhoff, G. -J, Zardini, A. A., Zhang, K., van Zyl, P. G., Kerminen, V. -M, Carslaw, K. S., and Pandis, S. N.

Published
2011
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38. Supplementary material to "The AeroCom evaluation and intercomparison of organic aerosol in global models"

Author

Tsigaridis, K., primary, Daskalakis, N., additional, Kanakidou, M., additional, Adams, P. J., additional, Artaxo, P., additional, Bahadur, R., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Benedetti, A., additional, Bergman, T., additional, Berntsen, T. K., additional, Beukes, J. P., additional, Bian, H., additional, Carslaw, K. S., additional, Chin, M., additional, Curci, G., additional, Diehl, T., additional, Easter, R. C., additional, Ghan, S. J., additional, Gong, S. L., additional, Hodzic, A., additional, Hoyle, C. R., additional, Iversen, T., additional, Jathar, S., additional, Jimenez, J. L., additional, Kaiser, J. W., additional, Kirkevåg, A., additional, Koch, D., additional, Kokkola, H., additional, Lee, Y. H., additional, Lin, G., additional, Liu, X., additional, Luo, G., additional, Ma, X., additional, Mann, G. W., additional, Mihalopoulos, N., additional, Morcrette, J.-J., additional, Müller, J.-F., additional, Myhre, G., additional, Myriokefalitakis, S., additional, Ng, S., additional, O'Donnell, D., additional, Penner, J. E., additional, Pozzoli, L., additional, Pringle, K. J., additional, Russell, L. M., additional, Schulz, M., additional, Sciare, J., additional, Seland, Ø., additional, Shindell, D. T., additional, Sillman, S., additional, Skeie, R. B., additional, Spracklen, D., additional, Stavrakou, T., additional, Steenrod, S. D., additional, Takemura, T., additional, Tiitta, P., additional, Tilmes, S., additional, Tost, H., additional, van Noije, T., additional, van Zyl, P. G., additional, von Salzen, K., additional, Yu, F., additional, Wang, Z., additional, Zaveri, R. A., additional, Zhang, H., additional, Zhang, K., additional, Zhang, Q., additional, and Zhang, X., additional

Published
2014
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39. Chemical composition, main sources and temporal variability of PM<sub>1</sub> aerosols in southern African grassland

Author

Tiitta, P., primary, Vakkari, V., additional, Croteau, P., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Josipovic, M., additional, Venter, A. D., additional, Jaars, K., additional, Pienaar, J. J., additional, Ng, N. L., additional, Canagaratna, M. R., additional, Jayne, J. T., additional, Kerminen, V.-M., additional, Kokkola, H., additional, Kulmala, M., additional, Laaksonen, A., additional, Worsnop, D. R., additional, and Laakso, L., additional

Published
2014
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40. Atmospheric boundary layer top height in South Africa: measurements with lidar and radiosonde compared to three atmospheric models

Author

Korhonen, K., primary, Giannakaki, E., additional, Mielonen, T., additional, Pfüller, A., additional, Laakso, L., additional, Vakkari, V., additional, Baars, H., additional, Engelmann, R., additional, Beukes, J. P., additional, Van Zyl, P. G., additional, Ramandh, A., additional, Ntsangwane, L., additional, Josipovic, M., additional, Tiitta, P., additional, Fourie, G., additional, Ngwana, I., additional, Chiloane, K., additional, and Komppula, M., additional

Published
2013
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41. Chemical composition, main sources and temporal variability of PM1 aerosols in southern African grassland

Author

Tiitta, P., primary, Vakkari, V., additional, Josipovic, M., additional, Croteau, P., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Venter, A. D., additional, Jaars, K., additional, Pienaar, J. J., additional, Ng, N. L., additional, Canagaratna, M. R., additional, Jayne, J. T., additional, Kerminen, V.-M., additional, Kulmala, M., additional, Laaksonen, A., additional, Worsnop, D. R., additional, and Laakso, L., additional

Published
2013
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42. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP) at high black carbon mass concentration levels

Author

Hyvärinen, A.-P., primary, Vakkari, V., additional, Laakso, L., additional, Hooda, R. K., additional, Sharma, V. P., additional, Panwar, T. S., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Josipovic, M., additional, Garland, R. M., additional, Andreae, M. O., additional, Pöschl, U., additional, and Petzold, A., additional

Published
2013
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43. Estimating the concentration of nucleation mode aerosol particles over South Africa using satellite remote sensing measurements

Author

Sundström, A.-M., primary, Nikandrova, A., additional, Atlaskina, K., additional, Nieminen, T., additional, Vakkari, V., additional, Laakso, L., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Josipovic, M., additional, Venter, A. D., additional, Jaars, K., additional, Pienaar, J. J., additional, Piketh, S., additional, Wiedensohler, A., additional, Chiloane, E. K., additional, Leeuw, G. de, additional, and Kulmala, M., additional

Published
2013
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44. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP) at high black carbon mass concentration levels

Author

Hyvärinen, A.-P., primary, Vakkari, V., additional, Laakso, L., additional, Hooda, R. K., additional, Sharma, V. P., additional, Panwar, T. S., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Josipovic, M., additional, Garland, R. M., additional, Andreae, M. O., additional, Pöschl, U., additional, and Petzold, A., additional

Published
2012
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45. South African EUCAARI measurements: seasonal variation of trace gases and aerosol optical properties

Author

Laakso, L., primary, Vakkari, V., additional, Virkkula, A., additional, Laakso, H., additional, Backman, J., additional, Kulmala, M., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Tiitta, P., additional, Josipovic, M., additional, Pienaar, J. J., additional, Chiloane, K., additional, Gilardoni, S., additional, Vignati, E., additional, Wiedensohler, A., additional, Tuch, T., additional, Birmili, W., additional, Piketh, S., additional, Collett, K., additional, Fourie, G. D., additional, Komppula, M., additional, Lihavainen, H., additional, de Leeuw, G., additional, and Kerminen, V.-M., additional

Published
2012
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46. Impact of CYP2D6genotype on amitriptyline efficacy for the treatment of diabetic peripheral neuropathy: a pilot study

Author

Chaudhry, Mamoonah, Alessandrini, Marco, Rademan, Jacobus, Dodgen, Tyren M, Steffens, Francois E, van Zyl, Danie G, Gaedigk, Andrea, and Pepper, Michael S

Abstract

Aim:Therapy with low-dose amitriptyline is commonly used to treat painful diabetic peripheral neuropathy. There is a knowledge gap, however, regarding the role of variable CYP2D6-mediated drug metabolism and side effects (SEs). We aimed to generate pilot data to demonstrate that SEs are more frequent in patients with variant CYP2D6alleles. Method:To that end, 31 randomly recruited participants were treated with low-dose amitriptyline for painful diabetic peripheral neuropathy and their CYP2D6gene sequenced. Results:Patients with predicted normal or ultra-rapid metabolizer phenotypes presented with less SEs compared with individuals with decreased CYP2D6 activity. Conclusion:Hence, CYP2D6genotype contributes to treatment outcome and may be useful for guiding drug therapy. Future investigations in a larger patient population are planned to support these preliminary findings.

Published
2017
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47. General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

Author

Kulmala, M., primary, Asmi, A., additional, Lappalainen, H. K., additional, Baltensperger, U., additional, Brenguier, J.-L., additional, Facchini, M. C., additional, Hansson, H.-C., additional, Hov, Ø., additional, O'Dowd, C. D., additional, Pöschl, U., additional, Wiedensohler, A., additional, Boers, R., additional, Boucher, O., additional, de Leeuw, G., additional, Denier van der Gon, H. A. C., additional, Feichter, J., additional, Krejci, R., additional, Laj, P., additional, Lihavainen, H., additional, Lohmann, U., additional, McFiggans, G., additional, Mentel, T., additional, Pilinis, C., additional, Riipinen, I., additional, Schulz, M., additional, Stohl, A., additional, Swietlicki, E., additional, Vignati, E., additional, Alves, C., additional, Amann, M., additional, Ammann, M., additional, Arabas, S., additional, Artaxo, P., additional, Baars, H., additional, Beddows, D. C. S., additional, Bergström, R., additional, Beukes, J. P., additional, Bilde, M., additional, Burkhart, J. F., additional, Canonaco, F., additional, Clegg, S. L., additional, Coe, H., additional, Crumeyrolle, S., additional, D'Anna, B., additional, Decesari, S., additional, Gilardoni, S., additional, Fischer, M., additional, Fjaeraa, A. M., additional, Fountoukis, C., additional, George, C., additional, Gomes, L., additional, Halloran, P., additional, Hamburger, T., additional, Harrison, R. M., additional, Herrmann, H., additional, Hoffmann, T., additional, Hoose, C., additional, Hu, M., additional, Hyvärinen, A., additional, Hõrrak, U., additional, Iinuma, Y., additional, Iversen, T., additional, Josipovic, M., additional, Kanakidou, M., additional, Kiendler-Scharr, A., additional, Kirkevåg, A., additional, Kiss, G., additional, Klimont, Z., additional, Kolmonen, P., additional, Komppula, M., additional, Kristjánsson, J.-E., additional, Laakso, L., additional, Laaksonen, A., additional, Labonnote, L., additional, Lanz, V. A., additional, Lehtinen, K. E. J., additional, Rizzo, L. V., additional, Makkonen, R., additional, Manninen, H. E., additional, McMeeking, G., additional, Merikanto, J., additional, Minikin, A., additional, Mirme, S., additional, Morgan, W. T., additional, Nemitz, E., additional, O'Donnell, D., additional, Panwar, T. S., additional, Pawlowska, H., additional, Petzold, A., additional, Pienaar, J. J., additional, Pio, C., additional, Plass-Duelmer, C., additional, Prévôt, A. S. H., additional, Pryor, S., additional, Reddington, C. L., additional, Roberts, G., additional, Rosenfeld, D., additional, Schwarz, J., additional, Seland, Ø., additional, Sellegri, K., additional, Shen, X. J., additional, Shiraiwa, M., additional, Siebert, H., additional, Sierau, B., additional, Simpson, D., additional, Sun, J. Y., additional, Topping, D., additional, Tunved, P., additional, Vaattovaara, P., additional, Vakkari, V., additional, Veefkind, J. P., additional, Visschedijk, A., additional, Vuollekoski, H., additional, Vuolo, R., additional, Wehner, B., additional, Wildt, J., additional, Woodward, S., additional, Worsnop, D. R., additional, van Zadelhoff, G.-J., additional, Zardini, A. A., additional, Zhang, K., additional, van Zyl, P. G., additional, Kerminen, V.-M., additional, S Carslaw, K., additional, and Pandis, S. N., additional

Published
2011
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48. South African EUCAARI – measurements: a site with high atmospheric variability

Author

Laakso, L., primary, Vakkari, V., additional, Laakso, H., additional, Virkkula, A., additional, Kulmala, M., additional, Beukes, J. P., additional, van Zyl, P. G., additional, Pienaar, J. J., additional, Chiloane, K., additional, Gilardoni, S., additional, Vignati, E., additional, Wiedensohler, A., additional, Tuch, T., additional, Birmili, W., additional, Piketh, S., additional, Collett, K., additional, Fourie, G. D., additional, Komppula, M., additional, Lihavainen, H., additional, de Leeuw, G., additional, and Kerminen, V.-M., additional

Published
2010
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50. Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements.

Author

Giannakaki, E., van Zyl, P. G., Müller, D., Balis, D., and Komppula, M.

Abstract

Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type is available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol proper ties, i.e. effective radius and single scattering, albedo were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr; 0.9 ± 0.4% and 2.3 ± 0.5, respectively for urban/industrial aerosols, while these values were 92 ± 10 sr; 3.2 ± 1.3%; 2.0 ± 0.4 respectively for biomass burning aerosols layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 µm for urban/industrial, biomass burning, and mixed biomass burning and desert dust aerosols, respectively, while the single scattering albedo at 532 nm were 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532 nm), respectively for these three types of aerosols. Our results were within the same range of previously reported values. [ABSTRACT FROM AUTHOR]

Published
2015
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