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258 result(s) for "Joubert, F"
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USING MONTE CARLO SIMULATION TO QUANTIFY THE COST IMPACT OF SYSTEMIC RISK FACTORS IN A PROJECT PORTFOLIO: A CASE STUDY
In terme van projekrisikobestuur word sistemiese risiko's geidentifiseer as risiko's wat 'n karakteristiek is van die omgewing waarbinne die projek uitgevoer word. Hierdie risiko's hou verband met (i) die aksies van die projekbestuurspan, (ii) hoe projekkontroles bestuur word en ineenskakel, en (iii) hoe die projek beplan en uitgevoer word. Hierdie artikel stel 'n metode voor wat gebruik kan word om die koste-impak van sistemiese risiko's op n projek portefeulje te bepaal waar daar 'n gebrek is aan 'n geldige paremetriese model vir die berekening van sistemiese risiko's se impak op 'n hele projekportefeulje. Dit word gedoen deur middel van risiko kwantifisering en Monte Carlo simulasie. Die resultaat toon 'n noemenswaardige impak van sistemiese risiko's op die risikoprofiel van die projekportefeulje, waar sistemiese risiko die gebeurlikheidsbegroting met +85.6 % verhoog het. Die suksesvolle bestuur van sistemiese risiko's kan 'n noemenswaardige effek op projek sukses uitoefen deur die beperking van onnodige vermorsing.
Herbaceous Legume Encroachment Reduces Grass Productivity and Density in Arid Rangelands
Worldwide savannas and arid grasslands are mainly used for livestock grazing, providing livelihood to over a billion people. While normally dominated by perennial C4 grasses, these rangelands are increasingly affected by the massive spread of native, mainly woody legumes. The consequences are often a repression of grass cover and productivity, leading to a reduced carrying capacity. While such encroachment by woody plants has been extensively researched, studies on similar processes involving herbaceous species are rare. We studied the impact of a sustained and massive spread of the native herbaceous legume Crotalaria podocarpa in Namibia's escarpment region on the locally dominant fodder grasses Stipagrostis ciliata and Stipagrostis uniplumis. We measured tussock densities, biomass production of individual tussocks and tussock dormancy state of Stipagrostis on ten 10 m x 10 m plots affected and ten similarly-sized plots unaffected by C. podocarpa over eight consecutive years and under different seasonal rainfalls and estimated the potential relative productivity of the land. We found the percentage of active Stipagrostis tussocks and the biomass production of individual tussocks to increase asymptotically with higher seasonal rainfall reaching a maximum around 300 mm while the land's relative productivity under average local rainfall conditions reached only 40% of its potential. Crotalaria podocarpa encroachment had no effect on the proportion of productive grass tussocks, but reduced he productivity of individual Stipagrostis tussocks by a third. This effect of C. podocarpa on grass productivity was immediate and direct and was not compensated for by above-average rainfall. Besides this immediate effect, over time, the density of grass tussocks declined by more than 50% in areas encroached by C. podocarpa further and lastingly reducing the lands carrying capacity. The effects of C. podocarpa on grass productivity hereby resemble those of woody encroachers. Therefore, against the background of global change, the spread of herbaceous legumes and the underlying patterns needs to be further investigated to develop adequate counter measures for a sustainable land use.
Preoperative Education for Less Outpatient Pain after Surgery (PELOPS trial) in orthopedic patients—study protocol for a randomized controlled trial
Background Successful pain management after outpatient surgery requires proper education leading to correct decisions on the analgesics use at home. Despite different strategies adopted, up to ½ of patients receive little or no information about the treatment of postoperative pain, 1/3 of them are not able to follow postoperative analgesia instructions. This leads to higher rates of unmet needs in pain treatment, post-discharge emergency calls, and readmissions. Structured educational interventions using psychological empowering techniques may improve postoperative pain management. We hypothesize that preoperative education on use of an improved pain scale to make correct pain management decisions will improve the quality of post-operative pain management at home and reduce analgesics-related side effects. Methods A total of 414 patients scheduled for an outpatient orthopedic surgery (knee/shoulder arthroscopic interventions) are included in this randomized (1:1) controlled trial. Patients in the control arm receive standard information on post-discharge pain management. Patients in the experimental arm receive structured educational intervention based on the rational perception of postoperative pain and discomfort (anchoring and improved pain scale), and the proper use of analgesics. There is no difference in post-discharge analgesics regimen in both arms. Patients are followed for 30 days post-discharge, with the primary outcome expressed as total pain relief score at 5 days. Secondary outcomes include the incidence of severe pain during 30 days, changes in sleep quality (Pittsburg Sleep Quality Assessment), and patients’ perception of postoperative pain management assessed with the International Pain Outcomes questionnaire at day 30 post-discharge. Discussion The developed intervention, based on an improved pain scale, offers the advantages of being non-surgery-specific, is easily administered in a short amount of time, and can be delivered individually or in-group, by physicians or nurses. Trial registration ClinicalTrials.gov NCT03754699 . Registered on November 27, 2018.
Effect of fire on the palatability of plants in an African woodland savanna: varying impacts depending on plant functional groups
Fire and herbivores are two important drivers of changes in vegetation composition, quality and dynamics and both are highly related to each other. Herbivores are known to respond to fire both in terms of foraging decisions and distribution. However, little is known about the actual changes in plant chemistry following a fire event and how long these changes will last. We investigated the effect of fire on two different plant functional groups (grasses and woody species) in a woodland savanna of southern Africa. We studied chemical compounds known to be important for palatability of five perennial grass and seven woody species (trees and shrubs) common in the woodland savanna and known to be utilized by herbivores. We wanted to know if plant chemistry differs between a recently burned site (burned 2 years ago) and a control site, burned 16 years ago, and if grasses and woody species show similar relative differences between sites ( i.e. , the plants’ response to fire). We found a clear difference in chemical composition patterns between the plant functional groups, with an almost homogenous response to fire among woody species, but higher variability in response among grass species. Furthermore, we found that woody species maintained a higher nutritional value even 2 years after burning, whereas grasses did not show clear differences among the two investigated sites. Hence, few years after burning, woody plants might still serve as an attraction for herbivores, especially browsers, in contrast to grasses. The knowledge about these differences between the two functional groups in response to fire is beneficial for the development of management strategies for large herbivores whether domestic or wild.
USING MONTE CARLO SIMULATION TO CREATE A RANKED CHECK LIST OF RISKS IN A PORTFOLIO OF RAILWAY CONSTRUCTION PROJECTS
When introducing quantified risk assessments at a South African state-owned freight company, a skills gap was found during the identification and quantified risk analysis. To help with risk identification, a checklist of risks for railway construction projects was developed. The basis of this checklist was 38 individual railway construction project risk registers that were collated into a single risk register. After the risks had been cleaned up and classified, a Monte Carlo simulation using @Risk software was done that produced a ranked check list of risks. This list of risks is valuable because subject matter experts developed it, and can be used as a risk identification checklist by stakeholders in similar projects. The simulation results also showed that project scope is an influencing factor on the ranking of risks.
Shifting thresholds and changing degradation patterns: climate change effects on the simulated long-term response of a semi-arid savanna to grazing
1. The complex, nonlinear response of dryland systems to grazing and climatic variations is a challenge to management of these lands. Predicted climatic changes will impact the desertification of drylands under domestic livestock production. Consequently, there is an urgent need to understand the response of drylands to grazing under climate change. 2. We enhanced and parameterized an ecohydrological savanna model to assess the impacts of a range of climate change scenarios on the response of a semi-arid African savanna to grazing. We focused on the effects of temperature and CO 2 level increase in combination with changes in interand intra-annual precipitation patterns on the long-term dynamics of three major plant functional types. 3. We found that the capacity of the savanna to sustain livestock grazing was strongly influenced by climate change. Increased mean annual precipitation and changes in intra-annual precipitation pattern have the potential to slightly increase carrying capacities of the system. In contrast, decreased precipitation, higher interannual variation and temperature increase are leading to a severe decline of carrying capacities owing to losses of the perennial grass biomass. 4. Semi-arid rangelands will be at lower risk of shrub encroachment and encroachment will be less intense under future climatic conditions. This finding holds in spite of elevated levels of atmospheric CO2 and irrespective of changes in precipitation pattern, because of the drought sensitivity of germination and establishment of encroaching species. 5. Synthesis and applications. Changes in livestock carrying capacities, both positive and negative, mainly depend on the highly uncertain future rainfall conditions. However, independent of the specific changes, shrub encroachment becomes less likely and in many cases less severe. Thus, managers of semi-arid rangelands should shift their focus from woody vegetation towards perennial grass species as indicators for rangeland degradation. Furthermore, the resulting reduced competition from woody vegetation has the potential to facilitate ecosystem restoration measures such as re-introduction of desirable plant species that are only little promising or infeasible under current climatic conditions. On a global scale, the reductions in standing biomass resulting from altered degradation dynamics of semi-arid rangelands can have negative impacts on carbon sequestration.
A perspective on the measurement of inflation credibility
Inflation targeting anchors inflation expectations, which are not within the sphere of control of the authorities, but can only be influenced over time by consistent policy.  As public distrust of inflation figures will feed through to inflation expectations, this paper highlights a comparison of the credibility of two different measures of inflation in terms of an inflation credibility barometer.  In a comparison of the barometer results to the analysis of inflation perceptions reported by other central banks, it is concluded that the barometer delivers superior results.  The main recommendation is that respondents should be requested in a follow-up study to indicate whether they attach a higher degree of credibility to the overall inflation rate or the rate used for targeting purposes.
A dominance shift in arid savanna: An herbaceous legume outcompetes local C4 grasses
The characteristic vegetation structure of arid savannas with a dominant layer of perennial grass is maintained by the putative competitive superiority of the C4 grasses. When this competitive balance is disturbed by weakening the grasses or favoring the recruitment of other species, trees, shrubs, single grass, or forb species can increase and initiate sudden dominance shifts. Such shifts involving woody species, often termed “shrub encroachment”, or the mass spreading of so‐called increaser species have been extensively researched, but studies on similar processes without obvious preceding disturbance are rare. In Namibia, the native herbaceous legume Crotalaria podocarpa has recently encroached parts of the escarpment region, seriously affecting the productivity of local fodder grasses. Here, we studied the interaction between seedlings of the legume and the dominant local fodder grass (Stipagrostis ciliata). We used a pot experiment to test seedling survival and to investigate the growth of Crotalaria in competition with Stipagrostis. Additional field observations were conducted to quantify the interactive effect. We found germination and growth of the legume seedlings to be facilitated by inactive (dead or dormant) grass tussocks and unhindered by active ones. Seedling survival was three times higher in inactive tussocks and Crotalaria grew taller. In the field, high densities of the legume had a clear negative effect on productivity of the grass. The C4 grass was unable to limit the recruitment and spread of the legume, and Crotalaria did outcompete the putative more competitive grass. Hence, the legume is able to spread and establish itself in large numbers and initiate a dominance shift in savannas, similar to shrub encroachment. An herbaceous, native legume has massively spread in arid savanna, Namibia, thereby reducing the productivity of local fodder grasses. Competition experiments demonstrate that the legume is not, or no longer, controlled by the grasses. Hence, we conclude that this spread is a novel type of dominance shift in savannas, similar to shrub encroachment.
In vitro evaluation of a novel Estradiol analogue with nanomolar antimitotic and carbonic anhydrase inhibitory activity/In vito-evaluering van 'n estradiol-analoog met nanomolare antimitoties- en koolsuuranhidrase inhiberende aktiwiteit
In the present study we describe the in vitro biological activity of 2-ethyl-3-0-sulphamoyl-estra-1,3,5(10),15-tetraen-17-ol (ESE-15-ol), a novel antimitotic compound with anticarbonic anhydrase activity. This study indicates that ESE-15-ol is a promising antimitotic anticancer drug that warrants further investigation.
A dominance shift in arid savanna: An herbaceous legume outcompetes local C 4 grasses
The characteristic vegetation structure of arid savannas with a dominant layer of perennial grass is maintained by the putative competitive superiority of the C 4 grasses. When this competitive balance is disturbed by weakening the grasses or favoring the recruitment of other species, trees, shrubs, single grass, or forb species can increase and initiate sudden dominance shifts. Such shifts involving woody species, often termed “shrub encroachment”, or the mass spreading of so‐called increaser species have been extensively researched, but studies on similar processes without obvious preceding disturbance are rare. In Namibia, the native herbaceous legume Crotalaria podocarpa has recently encroached parts of the escarpment region, seriously affecting the productivity of local fodder grasses. Here, we studied the interaction between seedlings of the legume and the dominant local fodder grass ( Stipagrostis ciliata ). We used a pot experiment to test seedling survival and to investigate the growth of Crotalaria in competition with Stipagrostis . Additional field observations were conducted to quantify the interactive effect. We found germination and growth of the legume seedlings to be facilitated by inactive (dead or dormant) grass tussocks and unhindered by active ones. Seedling survival was three times higher in inactive tussocks and Crotalaria grew taller. In the field, high densities of the legume had a clear negative effect on productivity of the grass. The C 4 grass was unable to limit the recruitment and spread of the legume, and Crotalaria did outcompete the putative more competitive grass. Hence, the legume is able to spread and establish itself in large numbers and initiate a dominance shift in savannas, similar to shrub encroachment.