Oorlewing van die skerpioen <i>Opistophthalmus pugnax</i> (Scorpionidae) ná blootstelling aan ’n letale dosis SO₂-gas

<span>Skerpioene is bekend vir hul aanpasbaarheid by toestande in ’n droë habitat, min voedsel en radioaktiewe bestraling. Niks is bekend oor hul aanpasbaarheid by skadelike gasse nie. Resultate van hierdie eksperiment by </span><em>Opistophthalmus pugnax </em><span>bewys dat hulle ’n hoë dosis van 1000 dele per miljoen SO</span>₂<span> kan oorleef wat nie die geval is by die mens nie. Byvoorbeeld, die suurstofverbruikskoers neem eerder toe van 4.16 µmol/g</span>^-1<span>uur</span>^-1<span>na 7.69 µmol/g</span>^-1<span>uur</span>^-1<span>, een uur ná blootstelling aan SO</span>₂<span>. Veertig minute na blootstelling was die ṀO</span>₂<span> steeds bykans twee keer hoër in vergelyking met die ṀO</span>₂<span> aan die begin. Hierdie bevinding moet deur verdere eksperimente nagevors word, veral wat die rol van spirakulumsluiting speel by blootstelling aan SO</span>₂<span>.</span

The stochastic determinants of happiness in South Africa: A micro-economic modelling approach

Orientation: The levels of happiness in South Africa have deteriorated as witnessed by recent increases in public protests. Research purpose: Based on a newly developed conceptual framework, the linear path of influence of a variety of determinants of happiness is challenged in this article. This is done by firstly postulating a potential sequence of influences through which underlying factors have impact on non-proximate factors, which in turn influence the proximate factors, which also affect happiness. Motivation for the study: Given the global interest on well-being, happiness as an indicator of subjective well-being is an important trend to review and reflect on. Based on trends in happiness ratings, South Africans are no longer as satisfied and happy with their lives as they were previously. Given the apparent high level of unhappiness in South Africa, this article aims to identify the various stochastic determinants of happiness within the South African context. Research approach/design and method: The predictability of the conceptual framework was tested by means of categorical regressions. Main findings: The results indicate that a stochastic happiness determination path exists from underlying to non-proximate, to proximate to happiness outcomes and not necessarily the linear path as per the traditional approach of investigation. The results of the study challenge policymakers in South Africa to rethink their current strategies as the current status quo will not necessarily have the desired results. Moreover, higher levels of happiness will only be possible if positive macro-dynamics go hand in hand with positive micro-dynamics. These include high levels of cognitive abilities among the population, the population striving for happiness, planning their personal and financial futures, having access to financial and risk products, and having sustainable income sources. Practical/managerial implications: Through the identification of the identification of the path by which happiness is influenced, programmes and policies designed to improve the subjective well-being of South Africans can be customised to ensure the correct action is taken at the correct level of initiation. Contribution/value-add: One of the contributions of this article is the development of a conceptual framework concerning the path or chain of influences across several layers of variables and not only the direct relationships, as is the norm. Although the relationships between identified determinants and happiness have been researched extensively, limited information is available concerning the path of influence in South Africa. The second contribution is therefore not to identify the direct determinants of happiness in South Africa through the conventional methods, but rather to test the potential path of influence of these factors on one another as well as on happiness based on the developed conceptual framework

Entrepreneurial knowledge and aspirations of dentistry students in South Africa

An investigation of the intentions and knowledge of entrepreneurship of final-year university dentistry students is reported, with particular regard to the factors of gender and race. A questionnaire survey was used with final-year dentistry students, over two years, at the University of the Western Cape in South Africa. The findings show that dentistry students across race and gender groups believed that entrepreneurship education was important. At least half of the students showed an interest in starting a business practice soon after their graduation and completion of a mandatory one-year internship, with more male students indicating an interest in starting a business than female students. More Black African students indicated interest compared to other race groups (Coloureds, Whites and Indians). There were no significant differences between male and female students with regard to knowledge of entrepreneurship, but there were significant differences with regard to race in the scores for knowledge of entrepreneurship, with White students scoring the highest and African students the lowest. The authors conclude that entrepreneurship education should be included in the curriculum in the final year of dentistry studies to encourage business practice start-up soon after the one-year internship period, with the aim of contributing to growth in employment.Department of HE and Training approved lis

Human papillomavirus-type distribution in South African women without cytological abnormalities : a peri-urban study

OBJECTIVES: Knowledge of human papillomavirus (HPV) distribution in the general population is crucial for the development of new HPV vaccines and to provide a baseline from which to monitor the impact of current HPV vaccines in the future. HPV-type distribution in the Tshwane area, South Africa, might be different to that in other regions and countries. DESIGN: This was a retrospective descriptive study, representative of women without cervical cytological abnormalities. SETTING SUBJECTS: Women attending primary health clinics in the region of Tshwane were screened for cervical abnormalities with conventional cytology. OUTCOME MEASURES: Women without cytological abnormalities were included, and HPV DNA typing, using HPV Linear® Array Genotyping Test (Roche Molecular Systems, Branchburg, USA) was performed on all women. RESULTS: Demographic data were available for 1 238 patients. The mean age was 40.9 years. The majority of the women (14.6%) were between 35 and 39 years of age. 19.4% of women were younger than 30 years of age. The prevalence of HPV types was 67.1% and high-risk HPV infections, 44.9%. The average number of HPV-type infections was 3.2 in the 845 patients with HPV infections. The most common high-risk virus was HPV 16 (10.8%), followed by HPV 51 (9.3%), and HPV 58 (7.9%). HPV 18 was observed in 5.9%, and HPV 45 in 7.5%, of participants. HPV 62 (15.6%) and HPV 84 (14.4%) were the most prevalent low-risk types. CONCLUSION: HPV infections were highly prevalent in this population. The prevalence of HPV 16 and 18 was higher than that reported in other world regions. HPV 16 was the most prevalent high-risk type infection in women without cytological abnormalities. HPV infections other than HPV 16 and 18 were also prevalent, and this is important for future vaccine development.The Cancer Association of South Africa and Discovery Foundation.http://www.sajgo.co.za/index.php/sajgoam201

Unique human papillomavirus-type distribution in South African women with invasive cervical cancer and the effect of human immunodeficiency virus infection

OBJECTIVES : Cervical cancer is the most common cause of cancer-related deaths among South African women. Viral types associated with cervical cancer may differ not only between countries and regions, but possibly also between human immunodeficiency virus (HIV)Yinfected and noninfected women. METHODS : In a population with high HIV prevalence, human papillomavirus (HPV)Ytype infections detected with DNA analyses were reported in a cohort of 299 women diagnosed with invasive cervical cancer. RESULTS : One hundred fifty-four women tested HIV negative, 77 tested HIV positive, and HIVstatuswas unknown for 68women. Themean age forHIV-positivewomenwas 41.3 years, and that for HIV-negative women was 55.8 years (P G 0.001). Ninety-two percent of women tested HPV-DNA positive. Human papillomavirus types 16 and/or 18 were present in 62% of HIV-negative women and 65% of HIV-positive women. The 5 most common HPV types in HIV-positive women were, in decreasing frequency, HPV 16, 18, 45, 33, and 58. In HIVnegative women, the most common HPV types were HPV 16, 18, 35, and 45, followed by HPV 33 and 52.Human papillomavirus type 45wasmore likely in the HIV positive compared with theHIV negative (odds ratio, 3.07; 95%confidence interval, 1.07Y8.77).TheHIV-positive women had more multiple high-risk HPV-type infections than did the HIV-negative women (27% vs 8%, P = 0.001). CONCLUSIONS : A high number of women in South Africa with cervical cancer are HIV positive. Without viral cross-protection, HPV vaccines should prevent around 65% of cervical cancers in this population. Human papillomavirus type 45 infection is significantly linked to HIV and important for future vaccine developments.Discovery Foundation.http://journals.lww.com/ijgc2016-06-30hb201

Estimation of wood volume and height of olive tree plantations using airborne discrete-return LiDAR data

The aim of this study is to analyze methodologies based on airborne LiDAR (light detection and ranging) technology of low pulse density points (0.5m(-2)) for height and volume quantification of olive trees in Viver (Spain). A total of 29 circular plots, each with a radius of 20m, were sampled and their volumes and heights were obtained by dendrometric methods. For these estimations, several statistics derived from LiDAR data were calculated in each plot. Regression models were used to predict volume and height. The results showed good performance for estimating volume (R-2=0.70) and total height (R-2=0.67).The authors appreciate the financial support provided by the Spanish Ministerio de Ciencia e Innovacion (Ministry for Science & Innovation) within the framework of the project AGL2010-15334 and by the Vice-Rectorate for Research of the Universitat Politecnica de Valencia [Grant PAID-06-12-3297; SP20120534].Estornell Cremades, J.; Velázquez Martí, B.; López Cortés, I.; Salazar Hernández, DM.; Fernández-Sarría, A. (2014). Estimation of wood volume and height of olive tree plantations using airborne discrete-return LiDAR data. GIScience and Remote Sensing. 51(1):17-29. https://doi.org/10.1080/15481603.2014.883209S1729511Estornell, J., Ruiz, L. A., Velázquez-Martí, B., & Fernández-Sarría, A. (2011). Estimation of shrub biomass by airborne LiDAR data in small forest stands. Forest Ecology and Management, 262(9), 1697-1703. doi:10.1016/j.foreco.2011.07.026García, M., Riaño, D., Chuvieco, E., & Danson, F. M. (2010). Estimating biomass carbon stocks for a Mediterranean forest in central Spain using LiDAR height and intensity data. Remote Sensing of Environment, 114(4), 816-830. doi:10.1016/j.rse.2009.11.021Hyyppa, J., Kelle, O., Lehikoinen, M., & Inkinen, M. (2001). A segmentation-based method to retrieve stem volume estimates from 3-D tree height models produced by laser scanners. IEEE Transactions on Geoscience and Remote Sensing, 39(5), 969-975. doi:10.1109/36.921414Kim, Y., Yang, Z., Cohen, W. B., Pflugmacher, D., Lauver, C. L., & Vankat, J. L. (2009). Distinguishing between live and dead standing tree biomass on the North Rim of Grand Canyon National Park, USA using small-footprint lidar data. Remote Sensing of Environment, 113(11), 2499-2510. doi:10.1016/j.rse.2009.07.010Moorthy, I., Miller, J. R., Berni, J. A. J., Zarco-Tejada, P., Hu, B., & Chen, J. (2011). Field characterization of olive (Olea europaea L.) tree crown architecture using terrestrial laser scanning data. Agricultural and Forest Meteorology, 151(2), 204-214. doi:10.1016/j.agrformet.2010.10.005Næsset, E. (2004). Accuracy of forest inventory using airborne laser scanning: evaluating the first nordic full-scale operational project. Scandinavian Journal of Forest Research, 19(6), 554-557. doi:10.1080/02827580410019544Popescu, S. C. (2007). Estimating biomass of individual pine trees using airborne lidar. Biomass and Bioenergy, 31(9), 646-655. doi:10.1016/j.biombioe.2007.06.022Popescu, S. C., Wynne, R. H., & Nelson, R. F. (2002). Estimating plot-level tree heights with lidar: local filtering with a canopy-height based variable window size. Computers and Electronics in Agriculture, 37(1-3), 71-95. doi:10.1016/s0168-1699(02)00121-7Velázquez-Martí, B., Estornell, J., López-Cortés, I., & Martí-Gavilá, J. (2012). Calculation of biomass volume of citrus trees from an adapted dendrometry. Biosystems Engineering, 112(4), 285-292. doi:10.1016/j.biosystemseng.2012.04.011Velázquez-Martí, B., Fernández-González, E., Estornell, J., & Ruiz, L. A. (2010). Dendrometric and dasometric analysis of the bushy biomass in Mediterranean forests. Forest Ecology and Management, 259(5), 875-882. doi:10.1016/j.foreco.2009.11.027Velázquez-Martí, B., Fernández-González, E., López-Cortés, I., & Salazar-Hernández, D. M. (2011). Quantification of the residual biomass obtained from pruning of trees in Mediterranean olive groves. Biomass and Bioenergy, 35(7), 3208-3217. doi:10.1016/j.biombioe.2011.04.042Yu, X., Hyyppä, J., Kaartinen, H., & Maltamo, M. (2004). Automatic detection of harvested trees and determination of forest growth using airborne laser scanning. Remote Sensing of Environment, 90(4), 451-462. doi:10.1016/j.rse.2004.02.00

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

Clinical evaluation of Corridor disease in Bos indicus (Boran) cattle naturally infected with buffalo-derived Theileria parva

Corridor disease (CD) is a fatal condition of cattle caused by buffalo-derived Theileria parva. Unlike the related condition, East Coast fever, which results from infection with cattle-derived T. parva, CD has not been extensively studied. We describe in detail the clinical and laboratory findings in cattle naturally infected with buffalo-derived T. parva. Forty-six cattle were exposed to buffalo-derived T. parva under field conditions at the Ol Pejeta Conservancy, Kenya, between 2013 and 2018. The first signs of disease observed in all animals were nasal discharge (mean day of onset was 9 days post-exposure), enlarged lymph nodes (10 days post-exposure), and pyrexia (13.7 days post-exposure). Coughing and labored breathing were observed in more than 50% of animals (14 days post-exposure). Less commonly observed signs, corneal edema (22%) and diarrhea (11%), were observed later in the disease progression (19 days post-exposure). All infections were considered clinically severe, and 42 animals succumbed to infection. The mean time to death across all studies was 18.4 days. The mean time from onset of clinical signs to death was 9 days and from pyrexia to death was 4.8 days, indicating a relatively short duration of clinical illness. There were significant relationships between days to death and the days to first temperature (chi2 = 4.00, p = 0.046), and days to peak temperature (chi2 = 25.81, p = 0.001), animals with earlier onset pyrexia died sooner. These clinical indicators may be useful for assessing the severity of disease in the future. All infections were confirmed by the presence of macroschizonts in lymph node biopsies (mean time to parasitosis was 11 days). Piroplasms were detected in the blood of two animals (4%) and 20 (43%) animals seroconverted. In this study, we demonstrate the successful approach to an experimental field study for CD in cattle. We also describe the clinical progression of CD in naturally infected cattle, including the onset and severity of clinical signs and pathology. Laboratory diagnoses based on examination of blood samples are unreliable, and alternatives may not be available to cattle keepers. The rapid development of CD requires recognition of the clinical signs, which may be useful for early diagnosis of the disease and effective intervention for affected animals

Estimation of shrub biomass by airborne LiDAR data in small forest stands

The presence of shrub vegetation is very significant in Mediterranean ecosystems. However, the difficulty involved in shrub management and the lack of information about behavior of this vegetation means that these areas are often left out of spatial planning projects. Airborne LiDAR (Light Detection And Ranging) has been used successfully in forestry to estimate dendrometric and dasometric variables that allow to characterize forest structure. In contrast, little research has focused on shrub vegetation. The objective of this study was to estimate dry biomass of shrub vegetation in 83 stands of radius 0.5 m using variables derived from LiDAR data. Dominant species was Quercus coccifera, one of the most characteristic species of the Mediterranean forests. Density of LiDAR data in the analyzed stands varied from 2 points/m(2) to 16 points/m(2), being the average 8 points/m(2) and the standard deviation 4.5 points/m(2). Under these conditions, predictions of biomass were performed calculating the mean height, the maximum height and the percentile values 80th, 90th, and 95th derived from LiDAR in concentric areas whose radius varied from 0.50 m to 3.5 m from the center of the stand. The maximum R(2) and the minimum RMSE for dry biomass estimations were obtained when the percentile 95th of LiDAR data was calculated in an area of radius 1.5 m, being 0.48 and 1.45 kg, respectively. For this radius, it was found that for the stands (n = 39) where the DTM is calculated with high accuracy (RMSE lower than 0.20 m) and with a high density of LiDAR data (more than 8 points/m(2)) the R(2) value was 0.73. These results show the possibility of estimating shrub biomass in small areas when the density of LiDAR data is high and errors associated to the DTM are low. These results would allow us to improve the knowledge about shrub behavior avoiding the cost of field measurements and clear cutting actions. (C) 2011 Elsevier B.V. All rights reserved.Estornell Cremades, J.; Ruiz Fernández, LÁ.; Velázquez Martí, B.; Fernández Sarriá, A. (2011). Estimation of shrub biomass by airborne LiDAR data in small forest stands. Forest Ecology and Management. 262(9):1697-1703. doi:10.1016/j.foreco.2011.07.026S16971703262

Inherited tolerance in cattle to the apicomplexan protozoan Theileria parva is associated with decreased proliferation of parasite-infected lymphocytes

Theileria parva is the causative agent of East Coast fever and Corridor disease, which are fatal, economically important diseases of cattle in eastern, central and southern Africa. Improved methods of control of the diseases are urgently required. The parasite transforms host lymphocytes, resulting in a rapid, clonal expansion of infected cells. Resistance to the disease has long been reported in cattle from T. parva-endemic areas. We reveal here that first- and second-generation descendants of a single Bos indicus bull survived severe challenge with T. parva, (overall survival rate 57.3% compared to 8.7% for unrelated animals) in a series of five field studies. Tolerant cattle displayed a delayed and less severe parasitosis and febrile response than unrelated animals. The in vitro proliferation of cells from surviving cattle was much reduced compared to those from animals that succumbed to infection. Additionally, some pro-inflammatory cytokines such as IL1β, IL6, TNFα or TGFβ which are usually strongly expressed in susceptible animals and are known to regulate cell growth or motility, remain low in tolerant animals. This correlates with the reduced proliferation and less severe clinical reactions observed in tolerant cattle. The results show for the first time that the inherited tolerance to T. parva is associated with decreased proliferation of infected lymphocytes. The results are discussed in terms of whether the reduced proliferation is the result of a perturbation of the transformation mechanism induced in infected cells or is due to an innate immune response present in the tolerant cattle