| 1. |
- Kulmala, M., et al.
(författare)
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General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) - integrating aerosol research from nano to global scales
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:24, s. 13061-13143
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their effects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several new aerosol parameterizations and computations modules for chemical transport and global climate models were developed and evaluated. These achievements and related studies have substantially improved our understanding and reduced the uncertainties of aerosol radiative forcing and air quality-climate interactions. The EUCAARI results can be utilized in European and global environmental policy to assess the aerosol impacts and the corresponding abatement strategies.
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| 2. |
- De Waal,, J.J., et al.
(författare)
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Towards understanding causality between work engagement and psychological capital
- 2013
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Ingår i: South African Journal of Industrial Psychology. - Cape Town : AOSIS. - 0258-5200 .- 2071-0763. ; 39:2
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Tidskriftsartikel (refereegranskat)abstract
- Orientation: It is of theoretical and practical interest to establish the sequential relationship between work engagement and positive organisational behaviour, as represented by the psychological capital (PsyCap) construct.Research purpose: The main aim of this study was to conceptualise and investigate the causal relationship and temporal order in the relationship between PsyCap and engagement by means of longitudinal data.Motivation for the study: The rationale for establishing the sequence of engagement and psychological capital lies in the fact that training interventions to enhance the organisational well-being of employees may need to be focused on either one or the other.Research design, approach and method: A longitudinal study with a cross-lagged panel design was conducted; data was gathered by means of a survey that was constructed for the purpose of the study. The survey contained the Utrecht Work Engagement Scale (UWES), and a measure of PsyCap. All employees within a chemical factory (N = 1003) were approached to provide data; 163 employees participated.Main findings: Results revealed that PsyCap at Time 1 (T1) did not significantly predict engagement at Time 2 (T2). Evidence does however exist that initial levels of employee engagement predict subsequent PsyCap.Practical/managerial implications: Results suggest that employee interventions aimed at protecting and fostering employee engagement may have implications for subsequent employee psychological capital.Contribution/value-add: As an empirical, longitudinal study to address the temporal order between PsyCap and work engagement, this study makes a contribution especially to theory, but also with practical implications by indicating that engagement precedes employee psychological capital.
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| 3. |
- Pienaar, J., et al.
(författare)
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The cognitive/affective distinction of job insecurity : validation and differential relations
- 2013
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Ingår i: Southern African Business Review. - 1998-8125. ; 17:2, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- Job insecurity as a work-related stressor is well established through three decades of research. It has been related to outcomes such as decreased job satisfaction, organisational commitment and performance as well as increased ill-health and organisational turnover. However, some important conceptual and theoretical issues are still under discussion, with implications for the measurement of the construct. We administered a short version of the measure of job insecurity originally devised by De Witte (2000), which distinguishes between cognitive and affective job insecurity. Data on job satisfaction, commitment, psychological ill-health and emotional exhaustion were also gathered from employees in a variety of South African organisations (N=1925) by means of anonymous surveys. Exploratory and confirmatory factor analyses revealed that the cognitive and affective dimensions of job insecurity could be distinguished in this sample of South African employees, and the two dimensions evidenced adequate reliability. Equivalence analyses showed that the measurement properties of the scale were invariant across various demographic groups. The relationships with outcome variables were investigated by means of correlations and regression analyses. Cognitive job insecurity was predictive of all outcome variables, whereas affective job insecurity primarily played a role for emotional exhaustion. Norm data concerning levels of cognitive and affective job insecurity are presented to guide future South African studies.
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| 4. |
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| 5. |
- Viljoen, S, et al.
(författare)
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A state-time epidemiology model of tuberculosis: Importance of re-infection
- 2012
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Ingår i: Computational biology and chemistry (Print). - : Elsevier. - 1476-9271 .- 1476-928X. ; 36, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- An epidemiological model is presented that considers five possible states of a population: susceptible (S), exposed (W), infectious (Y), in treatment (Z) and recovered (R). in certain instances transition rates (from one state to another) depend on the time spent in the state; therefore the states W, Y and Z depend on time and length of stay in that state - similar to age-structured models. The model is particularly amenable to describe delays of exposed persons to become infectious and re-infection of exposed persons. Other transitions that depend on state time include the case finding and diagnosis, increased death rate and treatment interruption. The mathematical model comprises of a set of partial differential and ordinary differential equations. Non-steady state solutions are first presented, followed by a bifurcation study of the stationary states.
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