75 research outputs found
First results of the SA Agulhas II mobile mini-neutron monitor: Instrumental characterization and environmental sensitivity
We present the first results of a new redesigned version of the mini-neutron monitor installed on the South African Research vessel, the SA Agulhas II. Measurements taken from the 2019/2020 relief voyages are presented. We show that the instrument is very sensitive to temperature variations when the ambient temperature is below 3oC. This is believed to be an instrumental effect. Additionally, we show the presence of high-frequency interference in the calculated waiting time distributions when the vessel reaches polar latitudes. We show that these periodic variations are only present in the intensity of secondary atmospheric particles and most likely related to the operation of the vessel’s ice radar. We are currently looking at moving the instrument to a more suitable location on board the SA Agulhas II where we will hopefully be able to operate the instrument in a continuous fashion for several years to come
NMDB@Athens: Hybrid symposium on cosmic ray studies with neutron detectors
A brief overview is given regarding the presentations delivered at the NMDB@Athens meeting which was held, in a hybrid fashion, in September 2022. Participants joined both remotely but also physically at the National and Kapodistrian University of Athens, Greece. Unlike traditional cosmic ray meetings and conferences where the focus is mainly on the science related to neutron monitor measurements, the ›NMDB@Athens‹ meeting uniquely also addresses hardware issues related to these instruments and, importantly, also databases where different data products can be accessed by a growing and increasingly diverse user base. The present overview outlines and introduces the more detailed articles contained in the proceedings
Die Nederduitse Gereformeerde Kerkorde van 1962: Die Dordtse Kerkorde aangepas by die eise van ons dag?
Why Has Human–Carnivore Conflict Not Been Resolved in Namibia?
Human–wildlife conflict has historically been portrayed as a management problem where solutions lie in technical changes or financial incentives. However, recent research shows many conflicts stem from social, economic, and political drivers. We undertook qualitative data collection on livestock farms to determine whether relationships between farmers and their workers affected frequency of reported livestock depredation in Namibia. We found that the conflict was affected by social and economic inequalities embedded in the previous apartheid regime. Macro- and microlevel socioeconomic problems created an environment where livestock depredation was exacerbated by unmotivated farm workers. Poor treatment of workers by farmers resulted in vengeful behaviors, such as livestock theft and wildlife poaching. Successfully addressing this situation therefore requires recognition and understanding of its complexity, rather than reducing it to its most simplistic part
Testing and Assessment in an International Context: Cross- and Multi-cultural Issues
Globalisation, increase of migration flows, and the concurrent worldwide competitiveness impose rethinking of testing and assessment procedures and practices in an international and multicultural context. This chapter reviews the methodological and practical implications for psychological assessment in the field of career guidance. The methodological implications are numerous and several aspects have to be considered, such as cross-cultural equivalence or construct, method, and item bias. Moreover, the construct of culture by itself is difficult to define and difficult to measure. In order to provide non-discriminatory assessment, counsellors should develop their clinical cross-cultural competencies, develop more specific intervention strategies, and respect cultural differences. Several suggestions are given concerning translation and adaptation of psychological instruments, developing culture specific measures, and the use of these instruments. More research in this field should use mixed methods, multi-centric designs, and consider emic and etic psychological variables. A multidisciplinary approach might also allow identifying culture specific and ecological meaningful constructs. Non-discriminatory assessment implies considering the influence and interaction of personal characteristics and environmental factors
Review of solar energetic particle models
Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they are the product of a broad set of physical processes from the corona out through the extent of the heliosphere, and provide insight into processes of particle acceleration and transport that are widely applicable in astrophysics. From the operations perspective, SEP events pose a radiation hazard for aviation, electronics in space, and human space exploration, in particular for missions outside of the Earth’s protective magnetosphere including to the Moon and Mars. Thus, it is critical to improve the scientific understanding of SEP events and use this understanding to develop and improve SEP forecasting capabilities to support operations. Many SEP models exist or are in development using a wide variety of approaches and with differing goals. These include computationally intensive physics-based models, fast and light empirical models, machine learning-based models, and mixed-model approaches. The aim of this paper is to summarize all of the SEP models currently developed in the scientific community, including a description of model approach, inputs and outputs, free parameters, and any published validations or comparisons with data.</p
Modelling of cosmic ray modulation in the heliosphere by stochastic processes
PhD (Space Physics), North-West University, Potchefstroom Campus, 2013The transport of cosmic rays in the heliosphere is studied by making use of a newly developed
modulation model. This model employes stochastic differential equations to numerically solve
the relevant transport equation, making use of this approach’s numerical advantages as well
as the opportunity to extract additional information regarding cosmic ray transport and the
processes responsible for it. The propagation times and energy losses of galactic electrons
and protons are calculated for different drift cycles. It is confirmed that protons and electrons
lose the same amount of rigidity when they experience the same transport processes. These
particles spend more time in the heliosphere, and also lose more energy, in the drift cycle
where they drift towards Earth mainly along the heliospheric current sheet. The propagation
times of galactic protons from the heliopause to Earth are calculated for increasing heliospheric
tilt angles and it is found that current sheet drift becomes less effective with increasing solar
activity. Comparing calculated propagation times of Jovian electrons with observations, the
transport parameters are constrained to find that 50% of 6 MeV electrons measured at Earth
are of Jovian origin. Charge-sign dependent modulation is modelled by simulating the proton
to anti-proton ratio at Earth and comparing the results to recent PAMELA observations.
A hybrid cosmic ray modulation model is constructed by coupling the numerical modulation
model to the heliospheric environment as simulated by a magneto-hydrodynamic model. Using
this model, it is shown that cosmic ray modulation persists beyond the heliopause. The
level of modulation in this region is found to exhibit solar cycle related changes and, more
importantly, is independent of the magnitude of the individual diffusion coefficients, but is
rather determined by the ratio of parallel to perpendicular diffusion.Doctora
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