An all-solid-state biocompatible ion-to-electron transducer for bioelectronics

Reported here is an all-solid-state organic electrochemical transistor based on the biopolymer melanin. The underlying mechanism is demonstrated using a unique hydration dependence protocol and explained using an adapted double capacitor model. The demonstration of an all-solid-state bioelectronic prototype is critical for the development of miniaturised bioelectronic logic

Cohomogeneity one manifolds and selfmaps of nontrivial degree

We construct natural selfmaps of compact cohomgeneity one manifolds with finite Weyl group and compute their degrees and Lefschetz numbers. On manifolds with simple cohomology rings this yields in certain cases relations between the order of the Weyl group and the Euler characteristic of a principal orbit. We apply our construction to the compact Lie group SU(3) where we extend identity and transposition to an infinite family of selfmaps of every odd degree. The compositions of these selfmaps with the power maps realize all possible degrees of selfmaps of SU(3).Comment: v2, v3: minor improvement

Cross pathogenicity of Neofusicoccum australe and Neofusicoccum stellenboschiana on grapevine and selected fruit and ornamental trees

[EN] Neofusicoccum australe is one of the most important Botryosphaeriaceae pathogens occurring on fruit and vine crops. This fungus was recently taxonomically reassessed, identifying N. stellenboschiana as a separate species. Previous pathogenicity studies used N. stellenboschiana and N. australe isolates as N. australe, so assessment of the pathogenicity of these two species on grapevine and other hosts was required. A pathogenicity trial was conducted on detached shoots of grapevine, plum, apple, olive and Peruvian pepper tree. Shoots were individually inoculated with 11 N. australe and eight N. stellenboschiana isolates originally isolated from grapevine, plum, apple, olive, Peruvian pepper and fig. Both species formed lesions on all five hosts and were reisolated 5 weeks post-inoculation. In general, the largest lesions were formed on plum and smallest on Peruvian pepper. Isolate host origin did not influence ability to cause lesions on other hosts. Isolates of N. australe and N. stellenboschiana differed in virulence on the various hosts, ranging from those that caused the largest lesions, a group causing intermediate lesions, and another causing lesions similar to uninoculated controls. The study demonstrates that N. australe and N. stellenboschiana isolates originating from various fruit hosts can infect alternative hosts including grapevine and other major fruit crops.This research developed from a mobility sojourn funded by the Erasmus Mundus Joint Master Degrees Programme of the European Commission under the PLANT HEALTH Project. The authors also acknowledge financial support from ARC Infruitec-Nietvoorbij and the National Research Foundation of South Africa (NRF UID88771). Technical Assistance was provided by Carine Vermeulen, Danie Marais, Julia Marais, Muriel Knipe, Lydia Maart, Christopher Paulse, Bongiwe Sokwaliwa, Nadeen van Kervel, and Levocia Williams (Plant Protection Division, ARC Infruitec-Nietvoorbij).Mojeremane, K.; Lebenya, P.; Du Plessis, IL.; Van Der Rijst, M.; Mostert, L.; Armengol Fortí, J.; Halleen, F. (2020). Cross pathogenicity of Neofusicoccum australe and Neofusicoccum stellenboschiana on grapevine and selected fruit and ornamental trees. PHYTOPATHOLOGIA MEDITERRANEA. 59(3):581-593. https://doi.org/10.14601/Phyto-11609S58159359

Mathematical models and the fight against diseases in Africa

n this age of molecular biology, The healthcare industry, politicians and the community at large are trying to find ‘magic bullet’ drugs and vaccines to conquer disease. Although smallpox has been eradicated and polio may soon be a scourge of the past, many pathogens replicate rapidly and mutate prodigiously, enabling them to evolve ways to circumvent our immune systems, as well as our drugs and vaccines. To fight and win the war against new emerging infections such as HIV/AIDS, TB and now SARS (severe acute respiratory syndrome), it is important to understand the temporal and spatial dynamics of the pathogens in human and, in some cases, animal reservoirs or vector populations. It is also necessary to understand the complex web of socio-economic factors pertinent to controlling the spread of disease, so that feasible, affordable and, most importantly, effective public-health policies can be devised and implemented

Bayesian highest posterior density intervals for the availability of a system with a 'rest-period' for the repair facility

CITATION: Yadavalli, V. S. S., et al. 2001. Bayesian highest posterior density intervals for the availability of a system with a 'rest-period' for the repair facility. South African Journal of Industrial Engineering, 12(2):17-24, doi:org/10.7166/12-2-345.The original publication is available at http://sajie.journals.ac.zaIn this paper Bayesian estimation for the steady state availability of a one-unit system with a rest-period for the repair facility is studied. The assumption is that the repair facility takes rest with probability p after each repair completion and the facility does not take the same with probability (l - p). The prior information is assumed to be vague and the Jeffreys' prior is used for the unknown parameters in the system. Gibbs sampling is used to derive the posterior distribution of the availability and subsequently the highest posterior density (HPD) intervals. A numerical example illustrates these results.In hierdie artikel word die Bayes-beraming van die ewewigstoestandsbeskikbaarheid van 'n stelsel wat afwisselend gebruik word, voorgestel. Daar word veronderstel dat die herstelfasiliteit na voltooiing van elke herstel of 'n rustydperk binnegaan of nie. Die rustydperk sal geneem word met waarskynlikheid p en die waarskynlikheid dat daar nie 'n rustydperk geneem word nie, is (l - p). Jeffrey se a priori-verdeling word vir die onbekende parameters in die stelsel aanvaar. Gibbs-steekproefneming word gebruik om die a posterioriverdeling van die beskikbaarheid en daarna die hoogste a posteriori-digtheidsintervalle (HPD) af te lei. 'n Numeriese voorbeeld illustreer hierdie resultate.http://sajie.journals.ac.za/pub/article/view/345Publisher's versio

Venous bicarbonate and creatine kinase as diagnostic and prognostic tools in the setting of acute traumatic rhabdomyolysis

Background. Myorenal or crush syndrome often develops following soft-tissue traumatic injury. It is a spectrum of disease that may result in severe renal dysfunction and kidney injury requiring renal replacement therapy.Objectives. To review a large cohort of patients with so-called myorenal or crush syndrome and assess the biochemical markers of venous bicarbonate and creatine kinase as predictors for the development of acute kidney injury (AKI).Methods. All patients with myorenal syndrome who presented to Khayelitsha District Hospital, Cape Town, South Africa (SA), and Ngwelezana Hospital, Empangeni, KwaZulu-Natal, SA, between January and December 2017 were identified and reviewed.Results. A total of 212 patients were included in the study. At both hospitals, 94% of the patients were male. Using the Pearson correlation coefficient, we compared creatinine kinase (CK) against serum creatinine. The mean CK level was 5 311.8 U/L and the mean creatinine level 133.457 μmol/L. The r-value was 0.2533. Although this is a technically positive correlation, the relationship between the variables is weak. Using the Pearson R Calculator, we inserted the r-value to calculate the p-value. The p-value was 0.000208. When comparing venous bicarbonate (HCO3) against creatinine, the mean HCO3 level was 22.296 mmol/L and the mean creatinine level 162.053 μmol/L. The r-value was –0.3468. Although this is a technically negative correlation, the relationship between the variables is weak. Using the Pearson R Calculator, we inserted the r-value to calculate the p-value. The p-value was 0.000013. The inverse ratio shown with HCO3 v. creatinine, although still a weak correlation, is significantly better in predicting an increase in creatinine compared with the weak positive correlation of CK v. creatinine.Conclusions. Although both venous HCO3 and CK showed a weak correlation with creatinine, the former performed significantly better in predicting AKI. In a resource-constrained system, we recommend that HCO3 be measured to assess patients with crush injury and that CK be regarded as a complementary modality

Regularity of Cauchy horizons in S2xS1 Gowdy spacetimes

We study general S2xS1 Gowdy models with a regular past Cauchy horizon and prove that a second (future) Cauchy horizon exists, provided that a particular conserved quantity $J$ is not zero. We derive an explicit expression for the metric form on the future Cauchy horizon in terms of the initial data on the past horizon and conclude the universal relation A\p A\f=(8\pi J)^2 where A\p and A\f are the areas of past and future Cauchy horizon respectively.Comment: 17 pages, 1 figur

Factors influencing time to diagnosis and treatment among pediatric oncology patients in Kenya

Early diagnosis and start of treatment are fundamental goals in cancer care. This study determines the time lag and the factors that influence the time to diagnosis and start of treatment. Study participants were parents of childhood cancer patients diagnosed between August 2013 and July 2014 in a hospital in Kenya. Patient, physician, diagnosis, treatment, health care system, and total delay were explored using a questionnaire. Demographic and medical data were collected from the patients' medical records. Parents of 99 childhood cancer patients were interviewed (response rate: 80%). Median total delay was 102 (9–1021) days. Median patient delay (4 days) was significantly shorter than health care system delay (median 87 days; P < .001). Diagnosis delay (median 94 days) was significantly longer than treatment delay (median 6 days; P < .001). days. Lack of health insurance at diagnosis and use of alternative medicine before attending conventional health services were associated with a significantly longer patient delay (P = .041 and P = .017, respectively). The type of cancer had a significant effect on treatment delay (P = .020). The type of health facility attended affected only patient delay (P = .03). Gender, age at diagnosis, stage of disease, parents' education level or income, and distance from hospital did not have a significant effect on the length of any type of delay. Training on childhood cancer should be included in the curricula for medical training institutes. In-service workshops should be held for the health workers already working. Families must be obligated to get health insurance. Families should be encourage to attend conventional health facilities and informed on symptoms of cancer through mass media

Attitudes and tolerance of private landowners shape the African wild dog conservation landscape in the greater Kruger National Park

The survival of wildlife ultimately relies on its acceptability to humans. The African wild dog Lycaon pictus is an endangered species that often comes into conflict with humans. Currently, the only viable population in South Africa resides in the Kruger National Park (KNP). To begin to understand the acceptability of wild dogs outside this important wild dog stronghold, we interviewed private landowners (n = 186) along the KNP western and southern boundaries. Respondents generally held positive attitudes towards wild dogs and had a good knowledge of them. Attitudes were also more positive when the property was part of a conservancy, indicating that the conservation landscape for wild dogs on private land outside the KNP is promising. However, the impact of edge effects such as disease transmission should not be ignored in future research, and creative solutions for mitigating these effects must be sought to ensure the future conservation of wild dogs.Jaguar Land Rover South Africa, Vaughan de la Harpe and his Climb for Kruger Wild Dogs Expedition, Richard Bosman and GCCL2 Management Services, and Rhodes University for the Henderson Prestigious Masters Postgraduate Scholarship.http://www.int-res.com/journals/esr/esr-homeam2018Mammal Research InstituteZoology and Entomolog