Freelance Consultant

Ahmadābād, India

Freelance Consultant

Ahmadābād, India

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Van Kesteren B.,Wageningen University | Hartogensis O.K.,Wageningen University | van Dinther D.,Wageningen University | Moene A.F.,Wageningen University | De Bruin H.A.R.,Freelance Consultant
Agricultural and Forest Meteorology | Year: 2013

This study introduces four methods for determining turbulent water vapour and carbon dioxide flux densities, the evapotranspiration and CO2 flux respectively. These methods combine scintillometer measurements with point-sampling measurements of scalar quantities and consequently have a faster statistical convergence than the eddy-covariance method. The scintillometer measures the friction velocity and stability averaged over space, allowing the time averaging to be a minute or less in homogenous conditions. This paper aims to thoroughly test the methods by analysing their sensitivity to the variables that go into the method and validate the methods with 30-min eddy-covariance data. Introduced are: the Bowen-variance method, the flux-variance method, the structure-parameter method, and the energy-balance method. Sensitivity analysis shows that each method is sensitive to the turbulence measurements of the scalar quantities that are specific to the method, as well as to the friction velocity. This demonstrates that the accuracy of the flux results from a correct representation of the turbulence variables used by the methods. Furthermore, a 30-min flux validation shows that the methods compare well to the independent eddy-covariance fluxes. We found that the structure-parameter method performs best - a low scatter (the correlation coefficient, r=0.99) and a 5% underestimation were observed. Also the other methods perform well, although the energy-balance did not close, because storage terms and CO2 flux were neglected. Furthermore, during the night the variance methods were influenced by non-stationarity in the measurement signal. Finally, we suggest using the correlation coefficients between temperature and scalar quantities to acquire the sign of the fluxes. Data for this study were gathered in May-June 2009 over a wheat field near Merken, Germany, in the framework of the TransRegio32 program. © 2012 Elsevier B.V.


Van Kesteren B.,Wageningen University | Hartogensis O.K.,Wageningen University | van Dinther D.,Wageningen University | Moene A.F.,Wageningen University | And 2 more authors.
Agricultural and Forest Meteorology | Year: 2013

This paper evaluates four methods to obtain accurate averaged flux estimates under conditions of non-stationary turbulence. In Part I (Van Kesteren et al., 2012), we introduced and evaluated these four combined methods for 30-min averaging intervals, notably the flux-variance method, the Bowen-variance method, the structure-parameter method, and the energy-balance method. The aim of this paper, Part II, is to validate the accuracy of the 1-min flux estimates of the CO2 flux, FCO2, and the evapotranspiration/latent-heat flux, LvE. Furthermore, we use the 1-min fluxes to investigate flux and vegetation responses under conditions of non-stationary turbulence. Using several validation methods, we show that both the eddy-covariance method and the energy-balance method are unsuitable for estimating fluxes over 1-min averaging intervals. The three other combined methods are more successful in determining 1-min fluxes. The random error is approximately half that of the eddy-covariance method, but still some issues limit the success. The Bowen-variance method has a +0.09 systematic error and moreover, 30% of the data had to be omitted, because the method requires more stringent conditions. Furthermore, the flux-variance method has a -0.15 systematic error. The structure-parameter method performs best of all methods and accurately resolves 1-min fluxes. With this method, we do a final validation with a different data set and show that also under dry conditions the method accurately resolves FCO2, although LvE was more difficult to resolve. In the last part, the structure-parameter method is successfully applied under conditions of non-stationary turbulence. We show that LvE and FCO2 have a different step response upon abrupt changes in solar radiation, because different processes drive these fluxes. Also, we observe a 2-min time lag between solar radiation and 1-min fluxes and show the relevance of taking this into account for determining light-response curves of the plants for both 1-min and 30-min averaging intervals. Furthermore, we show the relevance of 1-min fluxes for studying the light-response curves of plants for conditions with different temperature and humidity. Finally, we show that accurate estimates of 1-min averaged canopy resistances can be determined via the resistance expressions for sensible heat and LvE. As such, we show that vegetation can indeed modify its canopy resistance significantly within several minutes. © 2013 Elsevier B.V.


Lau C.L.,Queensland Childrens Medical Research Institute | Lau C.L.,University of Queensland | Lau C.L.,Australian National University | Skelly C.,Freelance Consultant | And 2 more authors.
BMC Infectious Diseases | Year: 2015

Background: Leptospirosis is an emerging infectious disease, with increasing frequency and severity of outbreaks, changing epidemiology of populations at risk, and the emergence of new serovars. Environmental drivers of disease transmission include flooding, urbanisation, poor sanitation, changes in land use and agricultural practices, and socioeconomic factors. In Queensland, human infection with Leptosira borgpetersenii serovar Arborea was first reported in 2001. This study aims to report the emergence of serovar Arborea in Queensland from 2001 to 2013, and investigate potential risk factors for infection and drivers of emergence. Methods: Data on laboratory-confirmed cases of human leptospirosis in Queensland were obtained from the enhanced surveillance system at the WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis in Brisbane, Australia. The changing epidemiology of serovar Arborea from 2001 to 2003 was described with respect to case numbers, proportion of leptospirosis cases attributed to the serovar, and geographic distribution. Differences in risk factors for the most common serovars were compared. Results: During this period, 1289 cases of leptospirosis were reported, including 233 cases attributed to serovar Arborea. Risk factors for infection include male gender (91 % of cases), occupation, and recreational exposure. Most common occupations recorded were banana workers (28.4 %), meat workers (7.2 %), dairy farmers (5.8 %), graziers/stockmen (5.5 %), 'other agricultural/rural workers' (16.4 %), and tourists or tourism operators (4.6 %). Time trend analysis showed that while non-Arborea cases decreased over the study period, Arborea cases increased by 3.4 cases per year. The proportion of annual cases attributed to Arborea peaked at 49 % in 2011 after unprecedented flooding in Queensland. Mapping of cases by residential location showed expansion of the geographic range of serovar Arborea, concentrating mostly around Brisbane, Cairns and Innisfail. Serovars varied significantly between ages and occupational groups, and serovar Arborea was most strongly associated with 'other agricultural/rural workers'. Conclusions: Leptospira borgpetersenii serovar Arborea has been emerging in Queensland since 2001, with increase in case numbers, the proportion of leptospirosis infections attributed to the serovar, as well as expansion of its geographic distribution. Reasons for this emergence are unknown, but climatic factors and environmental change are likely to have played important roles. © 2015 Lau et al.


Introduction: Through The Global Plan Towards the Elimination of New HIV Infections Among Children by 2015 and Keeping their Mothers Alive, leaders have called for broader action to strengthen the involvement of communities. The Global Plan aspires to reduce new HIV infections among children by 90 percent, and to reduce AIDS-related maternal mortality by half. This article summarizes the results of a review commissioned by UNAIDS to help inform stakeholders on promising practices in community engagement to accelerate progress towards these ambitious goals. Methods: This research involved extensive literature review and key informant interviews. Community engagement was defined to include participation, mobilization and empowerment while excluding activities that involve communities solely as service recipients. A promising practice was defined as one for which there is documented evidence of its effectiveness in achieving intended results and some indication of replicability, scale up and/or sustainability. Results: Promising practices that increased the supply of preventing mother-to-child transmission (PMTCT) services included extending community cadres, strengthening linkages with community- and faith-based organizations and civic participation in programme monitoring. Practices to improve demand for PMTCT included community-led social and behaviour change communication, peer support and participative approaches to generate local solutions. Practices to create an enabling environment included community activism and government leadership for greater involvement of communities. Committed leadership at all levels, facility, community, district and national, is crucial to success. Genuine community engagement requires a rights-based, capacity-building approach and sustained financial and technical investment. Participative formative research is a first step in building community capacity and helps to ensure programme relevance. Building on existing structures, rather than working in parallel to them, improves programme efficiency, effectiveness and sustainability. Monitoring, innovation and information sharing are critical to scale up. Conclusions: Ten recommendations on community engagement are offered for ending vertical transmission and enhancing the health of mothers and families: (1) expand the frontline health workforce, (2) increase engagement with community- and faithbased organizations, (3) engage communities in programme monitoring and accountability, (4) promote community-driven social and behaviour change communication including grassroots campaigns and dialogues, (5) expand peer support, (6) empower communities to address programme barriers, (7) support community activism for political commitment, (8) share tools for community engagement, (9) develop better indicators for community involvement and (10) conduct cost analyses of various community engagement strategies. As programmes expand, care should be taken to support and not to undermine work that communities are already doing, but rather to actively identify and build on such efforts. © 2012 Laurie Ackerman Gulaid and Kiragu K.


Vu B.N.,Formerly Family Health International And Currently With Pro For Appropriate Tec In Health | Mulvey K.P.,Substance Abuse and Mental Health Services Administration | Baldwin S.,Freelance Consultant | Nguyen S.T.,Formerly Family Health International And Currently With Pro For Appropriate Tec In Health
Culture, Health and Sexuality | Year: 2012

Knowledge about drug use and its association with HIV risk among men who have sex with men is limited. Although the HIV epidemic among this population in Vietnam is increasingly acknowledged, understanding the impact of drug use on the spread of HIV is largely lacking. Using qualitative data from in-depth interviews and focus group discussions with 93 drug users, 15 non-drug users and 9 community stakeholders, this analysis explores emerging patterns of drug use and risk factors for engaging in risk behaviours among drug-using men having sex with men, men selling sex and transgender individuals in Hanoi and Ho Chi Minh City. Findings revealed that drug use is shifting from heroin to ecstasy and ice. Drug users reported unsafe sex associated with drug use and men selling sex were particularly at elevated risk because of using drugs as a tool for sex work and trading sex for drugs. These findings are guiding development of programmes addressing unmet HIV-prevention needs in Vietnam. © 2012 Copyright Taylor and Francis Group, LLC.


Ugelvig L.V.,Copenhagen University | Ugelvig L.V.,AM Technology | Nielsen P.S.,Freelance Consultant | Boomsma J.J.,Copenhagen University | Nash D.R.,Copenhagen University
BMC Evolutionary Biology | Year: 2011

Background: Fragmentation of terrestrial ecosystems has had detrimental effects on metapopulations of habitat specialists. Maculinea butterflies have been particularly affected because of their specialized lifecycles, requiring both specific food-plants and host-ants. However, the interaction between dispersal, effective population size, and long-term genetic erosion of these endangered butterflies remains unknown. Using non-destructive sampling, we investigated the genetic diversity of the last extant population of M. arion in Denmark, which experienced critically low numbers in the 1980s. Results: Using nine microsatellite markers, we show that the population is genetically impoverished compared to nearby populations in Sweden, but less so than monitoring programs suggested. Ten additional short repeat microsatellites were used to reconstruct changes in genetic diversity and population structure over the last 77 years from museum specimens. We also tested amplification efficiency in such historical samples as a function of repeat length and sample age. Low population numbers in the 1980s did not affect genetic diversity, but considerable turnover of alleles has characterized this population throughout the time-span of our analysis. Conclusions: Our results suggest that M. arion is less sensitive to genetic erosion via population bottlenecks than previously thought, and that managing clusters of high quality habitat may be key for long-term conservation. © 2011 Ugelvig et al; licensee BioMed Central Ltd.


Li D.,Princeton University | Bou-Zeid E.,Princeton University | de Bruin H.A.R.,Freelance Consultant | de Bruin H.A.R.,King's College London
Boundary-Layer Meteorology | Year: 2012

Monin-Obukhov similarity functions for the structure parameters of temperature and humidity are needed to derive surface heat and water vapour fluxes from scintillometer measurements and it is often assumed that the two functions are identical in the atmospheric surface layer. Nevertheless, this assumption has not yet been verified experimentally. This study investigates the dissimilarity between the turbulent transport of sensible heat and water vapour, with a specific focus on the difference between the Monin-Obukhov similarity functions for the structure parameters. Using two datasets collected over homogeneous surfaces where the surface sources of sensible heat and water vapour are well correlated, we observe that under stable and very unstable conditions, the two functions are similar. This similarity however breaks down under weakly unstable conditions; in that regime, the absolute values of the correlations between temperature and humidity are also observed to be low, most likely due to large-scale eddies that transport unsteadiness, advection or entrainment effects from the outer layer. We analyze and demonstrate how this reduction in the correlation leads to dissimilarity between the turbulent transport of these two scalars and the corresponding Monin-Obukhov similarity functions for their structure parameters. A model to derive sensible and latent heat fluxes from structure parameters without measuring the friction velocity is tested and found to work very well under moderately to strongly unstable conditions (-z/L > 0. 5). Finally, we discuss the modelling of the cross-structure parameter over wet surfaces, which is crucial for correcting water vapour effects on optical scintillometer measurements and also for obtaining surface sensible and latent heat fluxes from the two-wavelength scintillometry. © 2011 Springer Science+Business Media B.V.


Rodriguez-Calvo T.,La Jolla Institute for Allergy and Immunology | Ekwall O.,La Jolla Institute for Allergy and Immunology | Ekwall O.,Gothenburg University | Amirian N.,La Jolla Institute for Allergy and Immunology | And 3 more authors.
Diabetes | Year: 2014

Type 1 diabetes (T1D) results from a complex interplay between genetic susceptibility and environmental factors that have been implicated in the pathogenesis of disease both as triggers and potentiators of β-cell destruction. CD8 T cells are the main cell type found in human islets, and they have been shown in vitro to be capable of killing β-cells overexpressing MHC class I. In this study, we report that CD8 T cells infiltrate the exocrine pancreas of diabetic subjects in high numbers and not only endocrine areas. T1D subjects present significantly higher CD8 T cell density in the exocrine tissue without the presence of prominent insulitis. Even T1D donors without remaining insulin-containing islets and long disease duration show elevated levels of CD8 T cells in the exocrine compartment. In addition, higher numbers of CD4+ and CD11c+ cells were found in the exocrine tissue. Preliminary data in type 2 diabetic (T2D) subjects indicate that overall, there might be a spontaneous inflammatory infiltration of the exocrine tissue, common to both T1D and T2D subjects. Our study provides the first information on the precise tissue distribution of CD8 T cells in pancreata from T1D, T2D, autoantibody-positive, and healthy control subjects. © 2014 by the American Diabetes Association.


Leonard M.,University of Adelaide | Westra S.,University of Adelaide | Phatak A.,CSIRO | Lambert M.,University of Adelaide | And 6 more authors.
Wiley Interdisciplinary Reviews: Climate Change | Year: 2014

Climate and weather variables such as rainfall, temperature, and pressure are indicators for hazards such as tropical cyclones, floods, and fires. The impact of these events can be due to a single variable being in an extreme state, but more often it is the result of a combination of variables not all of which are necessarily extreme. Here, the combination of variables or events that lead to an extreme impact is referred to as a compound event. Any given compound event will depend upon the nature and number of physical variables, the range of spatial and temporal scales, the strength of dependence between processes, and the perspective of the stakeholder who defines the impact. Modeling compound events is a large, complex, and interdisciplinary undertaking. To facilitate this task we propose the use of influence diagrams for defining, mapping, analyzing, modeling, and communicating the risk of the compound event. Ultimately, a greater appreciation of compound events will lead to further insight and a changed perspective on how impact risks are associated with climate-related hazards. © 2013 John Wiley & Sons, Ltd.


Colenbrander W.,Freelance consultant | van Koppen B.,International Water Management Institute
Water International | Year: 2013

During the past decade, smallholder groundwater irrigation with motor pumps has increased considerably in Zambia. This study analyzes an important but hitherto ignored factor for adoption: the supply chain of imported motor pumps. The main obstacles for farmers are identified as: the highly centralized supply chain and financing facilities in urban hubs; lack of information about prices, which vary significantly for the same make and model of pump; lack of information and training on proper use and maintenance; and lack of financing facilities. The Zambia National Farmers Union seems best placed to remove these obstacles. © 2013 2013 International Water Resources Association.

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