Wits researchers unravel the mystery of magmatic rocks consisting of random proportions of minerals
- Wits University
Geologists found the answer as to why certain magmatic rocks have varying proportions of minerals than what is expected of their type.
Researchers at Wits University in Johannesburg, South Africa, have found the answer to an enigma that has had geologists scratching their heads for years.
The question is that of how certain magmatic rocks that are formed through crystallisation in magmatic chambers in the Earth’s crust, defy the norm, and contain minerals in random proportions.
Normally, magmatic rocks consist of some fixed proportions of various minerals. Geologists know, for instance, that a certain rock will have 90% of one mineral and 10% of another mineral.
However, there are some magmatic rocks that defy this norm and do not adhere to this general rule of thumb. These rocks, called as non-cotectic rocks, contain minerals in completely random proportions.
One example is chromite-bearing anorthosite from the famous Bushveld Complex in South Africa. These rocks contain up to 15% to 20% of chromite, instead of only 1%, as would normally be expected.
“Traditionally, these rocks with a ‘wrong’ composition were attributed to either mechanical sorting of minerals that crystallised from a single magma or mechanical mixing of minerals formed from two or more different magmas,” says Professor Rais Latypov from the Wits School of Geosciences.
Seeing serious problems with both these approaches, Latypov and his colleague Dr Sofya Chistyakova, also from the Wits School of Geosciences, found that there is actually a simple explanation to this question – and it has nothing to do with the mechanical sorting or mixing of minerals to produce these rocks.
Their research, published in the journal Geology, shows that an excess amount of some minerals contained in these rocks may originate in the feeder conduits along which the magmas are travelling from the deep-seated staging chambers towards Earth’s surface.
“While travelling up through the feeder channels, the magma gets into contact with cold sidewalls and starts crystallising, thereby producing more of the mineral(s) than what should be expected,” says Chistyakova.
The general principle of this approach can be extended to any magmatic rocks with ‘wrong’ proportions of minerals in both plutonic and volcanic environments of the Earth.
“It is possible that a clue to some other petrological problems of magmatic complexes should be searched for in the feeder conduits rather than in magma chambers themselves. This appealing approach holds great promise for igneous petrologists working with basaltic magma complexes,” saysLatypov.
Wits’ Forbes appointed as editor-in-chief of international journal
- Wits University
Forbes is the first South African to take over the reins of the 100-year-old publication published by the UK’s Institute of Physics.
Professor Andrew Forbes from the Wits School of Physics has been announced as the new Editor-in-Chief of the Journal of Optics.
The Journal of Optics is the official journal of the European Optical Society and is published by the UK’s Institute of Physics (IoP).
The Journal of Optics has been in circulation for more than 100 years and is a highly regarded publication in the optical community. Forbes takes on the role after having spent several years as an editorial board member and topical editor.
“ To be Editor-in-Chief of a high-quality optics journal, one that has been in circulation for over a century, is a great honour,” says Forbes.
“I am looking forward to the challenge of setting the new strategy for the journal, leading the Editorial Board, and taking the journal forward to new heights. That the UK’s Institute of Physics would select someone from South Africa to lead the journal is a sign of the quality of people we have here at Wits,” says Forbes
Forbes is an active member of the international optics community, serving as an associate editor for Optics Express, AVS Quantum Science and PhotoniX.
Forbes is also the lead guest editor for a special issue on ‘Optics in Africa’.
This is a special issue to be published by the Optical Society of America (OSA) in their journals JOSA A and JOSA B. Forbes will be assisted by Dr Rim Cherif (Tunisia), Dr Alain Dikande (Cameroon) and fellow Wits researcher Dr Angela Dudley.
Wits researchers launch most comprehensive COVID-19 dashboard in South Africa
- Wits University
The dashboard is aimed at informing government, scientists, the media and general public with quick, easy-to-understand information on the current situation.
An interdisciplinary team of researchers at Wits University has launched the most comprehensive data dashboard on the COVID-19 virus in South Africa to date.
The dashboard, that shows the latest statistics on how the virus is affecting the population of South Africa, is updated on a daily basis, using official statistics from both local sources, such as the National Institute for Communicable Diseases (NICD) and international sources such as the World Health Organisation (WHO). The statistics on aspects such as the cumulative confirmed cases in South Africa, the daily confirmed cases, relative increases of infections are presented in colourful, easy-to-interpret visualisations. Other statistics include infections by gender, province, age and transmission routes.
“We are experts in analysing and interpreting big data, and we believe that it is important that someone put this data together and present a bigger picture of the impact of the virus on the country,” says Professor Bruce Mellado from the Wits School of Physics, who initiated the project. The team working on the project includes computer and data analysts, engineers and physicists.
The dashboard is aimed at informing government, scientists, the media and the general public with quick, easy-to-understand information on the current situation. It is updated every day approximately an hour after the release of the official COVID-19 update from the NICD. As more data becomes available, more features will be added to the dashboard.
Mellado is in talks with several government departments to get them to recognise as well as to add to the database, in order to make it a powerful tool in the fight against the virus.
“Our team believes in the power of knowledge to solve complex issues, and we hope that our strong ties and cooperation between the scientific community, the executive and the public can help overcome challenges such as the COVID-19 pandemic,” says Mellado.
Dinosaur "Easter eggs" reveal their contents in 3D
- Wits University
High-powered X-rays of the world’s oldest fossilised dinosaur embryos show surprising similarities to the embryos of today’s crocodiles, lizards and chickens.
Wits palaeontologists have digitally reconstructed the skull of a 200-million-year-old baby dinosaur by using powerful x-rays to scan the fragile contents of some of the oldest dinosaur eggs ever found.
The embryos, found in 1976 in Golden Gate Highlands National Park (Free State Province, South Africa) belong to South Africa’s iconic dinosaur Massospondylus carinatus, a 5-metre long herbivore that nested in the Free State region 200 million years ago.
In the research, led by Dr Kimberley Chapelle and Professor Jonah Choiniere of the Evolutionary Studies Institute, based at Wits University, was published today in Scientific Reports. In the publication, they present 3D reconstructions of the ~2cm-long skulls of some of the world’s oldest dinosaur embryos.
The scientific usefulness of the embryos was previously limited, due to their extremely fragile nature and tiny size. In 2015, Chapelle and Choiniere took the fossils to the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, where they were scanned by DrVincentFernandez, then working at the ESRF.
At the ESRF, a massive ring of electrons traveling at the speed of light emits high-powered X-ray beams that can be used to CT scan objects like fossils. The embryos were scanned at an unprecedented level of detail – at the resolution of an individual bone cell. With these data in hand, and nearly 3 years of data processing at Wits’ laboratory, Chapelle was able to reconstruct a 3D model of the baby dinosaur skull.
Up until now, it was believed that the embryos in those eggs had died just before hatching. However, during her study Chapelle noticed similarities with the developing embryos of living dinosaur relatives (crocodiles, chickens, turtles, and lizards). By comparing which bones of the skull were present at different stages of their embryonic development, Chapelle established that the Massospondylus embryos were actually much younger than previously thought – they had reached only 60% through their incubation period!
Among their other interesting findings, Chapelle found that each embryo had two types of teeth preserved in its developing jaws. One set was made up of very simple triangular teeth that would have been resorbed or shed before hatching, just like geckos and crocodiles today. The second set was very similar to that of adults, and would be the one that the embryos hatch with.
“I was really surprised to find that these embryos not only had teeth, but had two types of teeth. The teeth are so tiny; they range from 0.4 to 0.7mm wide. That’s smaller than the tip of a toothpick!”
The research showed that dinosaurs developed in the egg just like their modern-day reptilian relatives, whose embryonic developmental pattern hasn’t changed in 200 million years.
“It is incredible that in more than 250 million years of reptile evolution, the way the skull develops in the egg remains more or less the same. Goes to show – you don’t mess with a good thing,” says Choiniere.
Chapelle and her co-authors aren’t done with the research yet! They hope to apply their method to other dinosaur embryos to estimate their level of development. They will be looking at the rest of the skeleton of the Massospondylus embryos to see if it also shares similarities in development with today’s dinosaur relatives. The arms and legs of the Massospondylus embryos have already been used to show that hatchlings likely walked on two legs.
“No lab CT scanner in the world can generate these kinds of data,” says Fernandez, “only with a huge facility like the ESRF can we unlock the hidden potential of our most exciting fossils. This research is a great example of a global collaboration between Europe and the South African National Research Foundation”
Wits COVID-19 dashboard goes continental
- Wits University
New features added as inter disciplinary and inter-institutional collaboration data on the pandemic grows.
Wits University’s COVID-19 South Africa Dashboard has grown with new data features, including snapshot views of how the pandemic is spreading in Africa, as well as statistics showing world trends, being added. (As featured in this article in TIME Magazine.)
The dashboard, launched on 22 March, by Professor Bruce Mellado from the Wits School of Physics and Senior Scientist at iThemba LABS, has gained momentum with a number of volunteers from different disciplines working 24/7 to develop and maintain the dashboard. Wits university is working in collaboration with iThemba LABS of the National Research Foundation.
The visualisation of large quantities of data on the pandemic is a critical step in the analysis of that data. It provides an essential input for analysts to develop the first intuition with which to devise models. The relevance of the visualisation that the dashboard provides is therefore significant.
“The design, development and updating of the dashboard requires a large collaborative effort,” says Professor Barry Dwolatzky, Director of Wits University’s Joburg Centre for Software Engineering (JCSE). “I am assisting in the coordination of the project. Under Bruce Mellado’s leadership a team of highly dedicated and motivated student volunteers, drawn from a variety of disciplines, is working to develop and maintain the dashboard. Although all of us are locked down and working from home, a strong team spirit has developed. I find it interesting that few of us have actually met."
The dashboard is maintained daily and updated within minutes of Government’s announcements on the latest statistics. It provides historical data of relevant parameters, provincial and other breakdowns and it has undergone a number of upgrades since its release.
“Many of the upgrades have been requested by scientists and journalists from all over the country to improve the presentation of the South African data. Currently the site averages about 10 thousand views a day,” says Mellado.
One of the upgrades performed on the dashboard is the addition of a dashboard for the African continent that includes a detailed account of total cases, mortality and recoveries for all African counties. This addition has triggered a collaboration with the Botswana International University of Science and Technology (BIUST) to develop the first COVID-19 dashboard for Botswana, using data from the National Emergency Operation Centre of Botswana.
“This adds a new and important dimension to our existing collaborations with Wits and iThemba LABS,” says Professor Gregory Hillhouse, Head of the Department of Physics and Astronomy at BIUST.
“It is gratifying to see that one of our MSc students who has been trained at iThemba LABS, Mr Otsile Tikologo, is actively involved with this project.”
Another upgrade illustrates the global analysis of the spread in the conditions of containment (or “lockdown”) using epidemiological models. A number of countries have been selected for which containment measures have led to significant reduction in the rate of spread.
Data analysis and statistical treatment of this feature are performed using a frequentist framework. For this purpose the data processing framework ROOT developed by the European Laboratory CERN is used. Results are presented in terms of lower and upper curves for the cumulative number of positive cases as a function of time. These are estimated on the basis of a 68% confidence level. Predictions are updated on a daily basis.
“Understanding the impact of containment measures on the spread of the virus is essential to managing this crisis. Global data provide an invaluable insight into the dynamics of this complex problem,” says Mellado.
Professor Lee Berger to host online video lectures on human origins
- Wits University
Lectures will feature some of the University’s fossils, including the Taung Child, Homo naledi, Australopithecus sediba and various other fossils.
Wits University’s professor Lee Berger has launched a series of online video lectures that will cover various subjects on human origins and palaeoanthropology.
The lectures, which will be roughly 30 minutes long, will be featuring some of the University’s world-renowned fossils, including the Taung Child, Homo naledi, Australopithecus sediba and various other fossils from the Sterkfontein, Makapansgat and Swartkrans sites.
Wits University is the official custodian of some of the most precious fossils related to the origins of humankind.
“We at the university decided to do something special,” says Berger, a Professor in Palaeoanthropology and an Explorer at Large at National Geographic.
“We decided to give people a behind-the-scenes look at our fossil vault, which holds over 50% of the entire record of human origins known on the continent of Africa.”
This vault is off-limits to the public and mostly only scientists are allowed inside.
Starting with the discovery, history and a demonstration of the original Taung Child fossil, discovered in 1924 in South Africa, Berger will use these original fossils and artefacts that are associated with it to tell the stories of how these fossils were discovered, studied and how they add to our knowledge of our origins as a species.
“We are extremely fortunate at Wits to have such a valuable collection of strategic assets that we can use, to share our knowledge of what makes us human,” says Berger.
“My vision with these videos is that they can be viewed by the general public to give them a glimpse of the world of palaeoanthropology and human origins, as well as to be used as a teaching tool for teachers and lecturers in their classrooms during these difficult times.”
Hosted on a special section of the Wits University website, and released on Youtube, the lectures will start off with more general stories and descriptions of some of the fossils, and progress into the finer details of the study of palaeoanthropology.
“With today’s online media being so engaging, I hope that with these videos we can create a whole new way of studying and sharing some of our exciting discoveries, and, hopefully stimulate engaging discussions related to human origins.”
South Africa needs to end the lockdown: here’s a blueprint for its replacement
- Shabir Madhi, Alex van den Heever, David Francis, Imraan Valodia, Martin Veller and Michael Sachs.
Academics call on government to develop a comprehensive health and economic strategy if it is to prevent long term socio-economic damage caused by pandemic.
The public debate on strategies to tackle COVID-19 often unhelpfully positions health and economic considerations in a diametric fashion – as trade-offs. In fact, economic policy has health consequences. And health policy has economic consequences. The two need to be seen as parts of a coherent whole.
In the case of South Africa, the country currently faces three interrelated problems. These are the public health threat from the COVID-19 pandemic, the economic and health effects of the lockdown, and a range of intractable economic problems not directly due to the current pandemic. These include high unemployment, low economic growth and falling per capita income.
Any potentially viable response to COVID-19 needs to address all three aspects in concert. This is particularly important as the country plans for the next stage of its response after the lockdown. Focusing only on the health challenges and not paying attention to the economic issues will result in significantly higher economic costs, and will also undermine the health imperatives.
Our view is that a protracted lockdown won’t necessarily have the effect of ridding the country of the virus, but it will result in unacceptably high health and economic consequences.
The cost
The initial lockdown was prudent and is likely to have lowered the risk of community spread of SARS-CoV-2.
But the true number of COVID-19 (the disease caused by SARS-CoV-2) cases is difficult to quantify. A limited number of tests have been done, and community-wide screening for suspected infectious cases has been delayed.
The available evidence on the COVID-19 pandemic suggests that any initial containment of the disease through a lockdown will be short-lived. Also, it’s likely to result in a rebound of cases in the absence of aggressive community-wide screening for SARS-CoV-2 infectious cases, isolation of the identified cases and quarantine of their close contacts for at least 14 days.
On top of this, South Africa may find itself permanently harmed by the simultaneous destruction of both the demand and supply sides of the economy under an extended generalised lockdown.
This will have other unintended long term health and economic consequences. For example, an extended lockdown could result in the undermining of other health services, such as the immunisation of children.
The economic effects of a lockdown, too, are severe.
Early forecasts suggest significant economic disruption from the current lockdown, which is costing the economy an estimated R13 billion per day. Preliminary projections by the South African Reserve Bank indicate that South Africa could lose 370,000 jobs in 2020. Projections by private banking analysts (based on the initial 21-day lockdown) suggest a GDP contraction of 7% during 2020, leading to a fiscal deficit of 12% of GDP (forecast at 6.8% in the 2020 budget) and a debt-to-GDP ratio in excess of 81% in 2021. This means that the country’s already limited public finances will be further constrained.
Towards a post-lockdown strategy
Globally, attention is turning from initial containment through generalised lockdowns to short- and medium-term risk-based public health and economic strategies. We present some considerations for a health and economic policy beyond the lockdown in South Africa.
In this we proceed from the following assumptions:
The SARS-CoV-2 will not be eliminated in South Africa until either a vaccine is introduced (yet to be developed), or sufficient natural immunity in the population is achieved. It is therefore necessary to put in place and maintain a sustainable mitigation strategy for COVID-19 for the remainder of 2020, or until a vaccine is available (an optimistic timeline for this is 18-24 months).
A generalised lockdown is not a viable long-term prevention strategy for COVID-19 due to its deleterious effects, including the resultant long-term impact on society, public health and the economy.
Removal of the lockdown without appropriate health and economic measures will result in an excess mortality from COVID-19, resulting in further economic hardship.
South Africa’s health and economic strategy beyond the current lockdown must be designed to ensure good health care and be economically sustainable. We argue that the country needs to transition to a risk-based strategy which offers effective health protection and allows for the resumption of some economic activity.
This approach has been advocated by researchers in both Germany and the Indian state of Kerala.
First, mitigate the rapid spread of the virus, while allowing for natural immunity in the population to increase gradually.
Second, strengthen health care systems to ensure optimal treatment for as many patients as possible, both those with COVID-19 and those with other serious illnesses.
Third, protect individuals at high risk for severe COVID-19 disease; and
Fourth, make economic activities possible with measures in place to manage the health risks associated with these activities.
Economic and health strategies
At the highest level, there are three broad intervention strategies available to South Africa (summarised in the table below), adapted from a recent article by leading Australian health academics James Trauer, Ben Marais and Emma McBryde. We believe that option three is the only practicable one for South Africa. And the details of its implementation matter.
Table 1: Typology of interventions and risks
Adapted from (Trauer et al., 2020)
A health strategy based on an extended generalised lockdown is economically unsustainable. It is also damaging to public health. Instead, we need a unified health and economic strategy that allows for some economic activity while inhibiting the uncontrolled spread of the virus. This requires a number of health and economic measures to be implemented in a coordinated manner.
First, to reduce the rate of infections, the country must have ready the capability of mass virus testing and efficient contact tracing before the end of April 2020. This must be accompanied by a comprehensive approach to social distancing. Relying solely on screening of symptomatic individuals will not effectively reduce the rate of infection because high viral loads of SARS-CoV-2 in the upper airway occur in pre-symptomatic and possibly asymptomatic people.
To be successful, the scale of testing needs to be at least equivalent to that in South Korea (17,322 tests per day in South Africa, eventually testing 1 in 150 people). At best, it must be equivalent to that carried out in Germany (36,399 tests per day in South Africa).
Test turnaround times must result in identification of infected individuals within 12 to a maximum of 24 hours. This must be followed by immediate isolation and contact tracing. Isolation of infected individuals and contact quarantine must last for at least 14 days, either at home, if suitable, or in designated isolation and quarantine facilities.
The annual cost of conducting 17,000 tests per day is approximately R5 billion. There would perhaps be an additional annual cost of R4 billion for contact tracing and quarantine. These costs compare favourably to the daily economic cost (R13 billion) of the generalised lockdown.
Secondly, economic activities must be allowed in a way that is consistent with the aim of preventing the uncontrolled spread of the virus. Within the constraints of the health strategy outlined above, a risk-based economic strategy is required that balances economic and health imperatives.
Decisions on differential opening of the economy should be made in line with the criteria proposed in a recent paper by German researchers. This includes, for example, opening sectors with low risk of infection (highly automated factories) and less vulnerable populations (child-care facilities) first. It could also include areas with lower infection rates and less potential for the spread of COVID-19. Of course, these decisions will have to be based on a careful assessment of factors such as household structure and composition in South Africa, and public transport.
To do this, the country will need excellent data on the extent and location of any community outbreaks of the virus. Such data will be generated by mass testing, and accurate information about the ability of certain sectors of the economy to reopen safely and in compliance with the health protocols.
The health and economic strategy will thus need to be implemented in a dynamic fashion, responding to the latest evidence.
This article has been amended to reflect updated estimates of the daily cost of the lockdown.
Cas Coovadia, member of the University of the Witwatersrand Council, also contributed to the discussions that led to the writing of this article.
Wits engineers make face shields to protect healthcare workers
- Wits University
A team of innovative Witsies is using their design and engineering skills to create face shields in aid of the fight against COVID-19.
An amazing sense of social solidarity and patriotism has pervaded South Africa recently with many people offering their knowledge and skills to aid the country in its fight against the coronavirus.
The escalating spread of the virus has increased the demand for personal protective equipment (PPE) and medical supplies as more people test positive for COVID-19 daily. Healthcare facilities in the country are seeing a shortage in these supplies for their staff.
On Friday, 27 March 2020, Netcare 911, one of the healthcare facilities currently experiencing a massive shortage of protective gear, called on the 3D printing community to assist with printing head rings for face shields for use by medical staff treating patients with COVID-19.
Teams at Wits from the Digital Incubator at the Tshimologong Precinct, the School of Mechanical, Industrial and Aeronautical Engineering (MIA) along with the Transnet Centre of Systems Engineering (TCSE) and the Transnet Matlafat?o Centre (TMC) heeded the call and used their engineering prowess to assist with a solution to the problem.
Recognising that each head ring for the face shields would take approximately 90 minutes to produce and with limited 3D printing capacity, a team – made up of Guy Richards, Letlotlo Phohole, Moses Mogotlane, Palesa Riba and Randall Paton, ,decided on a laser cut solution that would save time.
“Netcare was going to provide the actual shield and clips to put it together. We were not happy with the limitation and wanted to use what is readily available to us, cheap to make, and light-weight. Most of all, we wanted to produce a complete product. We also anticipated long printing times with a 3D printer and possible filament shortages given the national drive for face shields and masks,” said Letlotlo Phohole, Acting Director of TCSE and TMC.
After numerous attempts on Monday, 30 March to cut the shield from downloaded files from GitHub and Thingiverse – a software development platform where over 40 million developers collaborate online to host and review code, manage projects, and build software – the Wits team re-designed the original designs, applying rapid prototyping processes, which they then cut using their laser cutter.
The face shields, which are made from polyvinyl chloride (PVC) sheeting, are a flat pack consisting of two pieces that can be rapidly assembled. “The School had stock of the PVC sheeting from another earlier project. The shields are therefore being provided at no cost to the hospitals”, says Paton.
Adhering to best safety practices is crucial in the production of these face shields.
“We ensure that after production they [face shields] are washed, rinsed, and dried to remove any potentially harmful residue from the laser cutting. This is done in a production line fashion and is now the tightest bottleneck in the project, given that we only have one working laser cutter,” added Paton.
With an average production time of 3 minutes (including setup time) to cut a set of pieces for each face shield, the team anticipates making 200 to 500 shields a day to help meet the growing demand of protective gear for medical staff.
“We have developed a system that lets us feed the rolled plastic directly into the cutting bed and draw more through when done so speed is climbing,” said Paton. The team has reduced the cutting time to 90 second per shield but the washing and drying still add to that time.
Four days since the call from Netcare 911, by Tuesday, 31 March, the Wits team had produced 140 face shields and distributed 120 to the Wits Donald Gordon Medical Centre and another 20 to the Wits Protection Services staff. An additional 300 face shields have been produced to date, of which 200 will be donated to Charlotte Maxeke Johannesburg Academic Hospital and 100 to Rahima Moosa Mother and Child Hospital. The Wits engineers hope to distribute face shields to Helen Joseph and Chris Hani Baragwanath hospitals, which are also Wits teaching hospitals.
Head of MIA, Professor Robert Reid hailed the team for their extraordinary contribution to society saying that they are upholding one of the five core values of the School, botho (humanity).
“A core value of our School is botho. We strive to nurture and develop the community of which we are part. During this time of national crisis, it is imperative that we use our skills and facilities in any way that will serve our community. I am therefore delighted that we are able to help keep safe the healthcare workers on the frontline in their fight against this awful pandemic.”
Paton said the nationwide response to the call had inspired him.
“I think that many South Africans, as a nation of ‘make-a-plan’, are frustrated by not being able to help in a tangible way during the lockdown and this has channelled that energy somewhere. This has been as inspiring to be a part of as watching everyone trying to help Netcare with 3D printing for the face shields. These are extraordinary people in extraordinary times.”
The Faculty of Engineering and the Built Environment plans to develop other medical equipment, including respirators, devices to prevent people from touching their faces, and medical masks (with filters made out of vacuum cleaner bags and make-up cotton pads designed by students of their own volition). These cross-disciplinary projects will involve people from different faculties at Wits and other stakeholder groups.
Over R100 000 has been raised for this initiative from 68 donors. If you would like to make a tax-deductible donation towards this cause or other initiatives at Wits University against COVID-19, please follow https://wits.devman.co.za/devman/covid-19/giving/ and donate directly to the Wits 足球竞彩app排名 Discretionary Fund or donate to the Wits Foundation. Bank details:
Wits University Foundation Standard Bank of South Africa Ltd Current Account number: 002900076 Branch code: 00 48 05
In the second episode of Professor Lee Berger’s series of lectures on human origin, he delves into his favourite hominid-bearing site, Makapansgat.
Prometheus, the Greek hero, who stole fire from the Gods. This is the name chosen for the new species of hominin, discovered in 1947 in the lime-quaries at Makapansgat in Limpopo, South Africa. The description of Australopithecus Prometheus in 19481 by Professor Raymond Dart of Wits University, proved to be another controversial find in the field of Palaeoanthropology2.
Inspired by the black colouring on the fossils, the types of fossils found and damage on some of the bones, Dart not only hypothesised that the black markings was signs that the bones were burnt, but he also came up with one of the most astounding ideas to come out of the science of anthropology – that humans in their deep ancestry were innately violent. One of the fossils – the lower jaw of a younger hominin was fractured by a blow that could well have led to his death. Was this the oldest case of murder in the world?
Dart’s theory of the osteodontokeratic culture, that early human ancestors developed bone tools and weapons, and that his discovery was the first evidence of violence in human nature was later proven to be false. However, his ideas inspired a number of fictional works, including the iconic opening scene of Stanley Kubric’s cult-classic, 2001 Space Odyssey. It also inspired a whole new science, called taphonomy and contributed to the study of human and primate behavioural sciences. It was the new science of taphonomy – the study of the grave – that showed Dart’s theories to be false, demonstrating that the markings on the Makapansgat fossils were naturally formed by the normal consumptive behaviours of animals like hyenas and other predators and scavengers that gnawed on the bones, and insects that had drilled holes in them. But Dart’s hypotheses help found these sciences3.
Dart, R. A. (1948). The Makapansgat proto‐human Australopithecus prometheus. American Journal of Physical Anthropology, 6(3), 259-284.
Berger, L.R. and Hawks, J., 2019. Australopithecus prometheus is a nomen nudum. American journal of physical anthropology, 168(2), pp.383-387.
Brain, C.K., 1997. The contribution of Raymond Dart to the development of cave taphonomy. Palaeontologia Africana, 33, pp.81-83.
Wits COVID-19 dashboard gets grant award from the IEEE
- Wits University
New features added as inter disciplinary and inter-institutional collaboration data on the pandemic grows.
Wits University’s COVID-19 dashboard has received a grant award by the IEEE. The IEEE is the world’s largest technical professional organisation dedicated to advancing technology. The IEEE has over 400,000 members from all continents. Through its members the IEEE promotes the development of research and technology transfer activities across 40 societies, which span a wide range of disciplines ranging from Aerospace to Vehicular technology, going through computing, electronics, industry applications and many others.
The grant award supports COVID-19-related visualisation and analytics for Southern Africa. The nature of the project is interdisciplinary, where medical data and expertise need to be combined with the wealth of methodologies and algorithms used in advanced analytics, Big Data and Data Science. Assumptions used in the project revolve around our current level of understanding of advanced analytics driven by Data Science and other disciplines. Both main-stream statistical frameworks, frequentist and Bayesian are an underlying assumption to model development. Input from the different medical, virology and custodians of static data pertaining to populations, social and medical vulnerabilities, access to medical infrastructure, prevalence of various relevant pre-existing conditions are also underlying assumptions.
"The project encapsulates methodologies in Data Science and Artificial Intelligence that effectively combine medical and other data to provide a comprehensive synthetic view of the predictive landscape.” says Professor Bruce Mellado of Wits University and iThemba LABS.
The chief goal of the project supported by the IEEE grant award is to control the number of people infected, hospitalisations, ICU admissions and mortality in South Africa and other countries. These outcomes will be predicted as a function of non-pharmaceutical interventions in the post-lockdown period to allow for the economy to reactivate. Analytical and predictive tools developed by these projections will assist policy makers to enact rules and regulations with which to revive economic activity, while preventing a massive outbreak of the virus. This is essential to alleviate the economic impact of the virus in African countries, in particular to slow down the rate of job losses.
This grant award provides various forms of support, including support for the organization of monthly webinars. “These webinars will be hosted by Wits University’s Joburg Centre for Software Engineering (JCSE) and will bring together panels of experts who are actively collaborating and working on the Wits COVID-19 dashboard project, including data scientists, modellers, medical experts and software engineers. The webinars will be open to all and will be advertised shortly,” says Professor Barry Dwolatzky.
Wits University’s COVID-19 dashboard continues to expand. A dashboard for the Gauteng Province has been put in place. Following a successful collaborative model developed with the Botswana International University of Science and Technology, three new dashboards have been launched: Nigeria, Eswatini and Namibia. This takes place in collaboration with local universities and institutions. Collaborative efforts have been established with Zimbabwe, Morocco and Senegal.
Professor Lee Berger explains the mystery surrounding human relatives living in Africa during the middle Pleistocene.
During the late middle Pleistocene – between 400 000 and 150 0000 years ago – the populations occupying Earth, and Africa specifically, looked very differently from what they do now. There is evidence for at least three forms of human relatives inhabiting Africa, including Homo heidelbergensis, Homo naledi and Homo sapiens(modern humans). Some, or all of these hominids made tools such as those associated with the middle stone age culture that began around 305 000 years ago. The question is, which of these human relatives got so crafty? Traditionally, it is thought that the larger brained species like Homo heidelbergensis and Homo sapiens should be associated with more complicated tool kits. But the answers may not be so simple. With three forms of early human relatives around, things are much more complicated, explains Professor Lee Berger.
Wits scientists along with Namibian, UK and US partners have shown how the smart application of existing interventions can reduce the transmission of malaria.
A trial by scientists at the Wits Research Institute for Malaria (WRIM), in collaboration with Namibian, UK, and US researchers demonstrates how mass drug administration and vector control can help eliminate malaria. A vector refers to an organism that transmits infection, as mosquitos infected with parasites transmit malaria to people.
The researchers published their findings in the prestigious journal The Lancet on World Malaria Day on 25 April even as countries the world over battle to contain transmission of the COVID-19.
The malaria trial conducted in northern Namibia demonstrates how malaria incidence can be reduced by up to 75% in settings where malaria transmission is mostly low but persistent, and plagued by sporadic outbreaks of higher numbers of malaria cases.
This scenario in Namibia is in many ways typical in neighbouring South Africa’s malaria endemic districts.
In a Global South and Global North collaboration, scientists at the WRIM at the University of the Witwatersrand in South Africa; the University of Namibia with the Namibia Ministry of Health and Social Services; the London School of Hygiene and Tropical Medicine; the University of California, San Francisco; and the University of Texas, Southwestern conducted this first ever randomized controlled trial of its kind.
“The reduction in cases was achieved using existing tools, namely anti-malarial drugs and insecticides, but deploying these in a ‘smart’ way, i.e., in close proximity of newly reported cases,” says Professor Immo Kleinschmidt, one of the Principal Investigators in the project, Honorary Professor in the Wits School of Pathology and Professor of Epidemiology in the Department of Infectious Disease at the London School of Hygiene and Tropical Medicine.
“Our results are derived from a community randomised controlled clinical trial. This means that the effects of the interventions are compared between groups that are similar in all respects apart from the intervention they are receiving. The findings are therefore very unlikely to be due to chance, and the conclusions are more robust than they would have been from an observational study.”
In this study, researchers conducted a trial to evaluate the effectiveness and safety of two interventions: (i) reactive focal mass drug administration (rfMDA) and (ii) reactive focal vector control (RAVC), and their combination.
This trial is unique because it is the first randomized controlled trial of rfMDA and/or RAVC. Study communities were randomly assigned to receive either rfMDA, or RAVC, or the combination, or neither of these two interventions (the latter being the control group).
The study took place in the Zambezi Region, northern Namibia, and targeted people that were at the highest risk of malaria infection based on their proximity within 500 meters of malaria index cases that emerged during the transmission season.
In one arm of the trial, these neighbours of any new malaria case were offered a standard dose of the anti-malarial drug Coartem?, without first testing whether these neighbours carried the parasite that causes malaria. This drug clear them of parasites even if the level of parasites they carried were below the density that can be detected by the standard rapid diagnostic test. The drug would also provide a short period of protection against new infections.
In another arm of the trial, neighbours of index cases had the interior walls of their houses sprayed with a highly effective insecticide, Pirimiphos-methyl, irrespective of whether or not their houses had previously been treated in the annual spray carried out routinely in such areas.
In the randomized trial, communities received either the drug, the house spray, the drug and the house spray, or neither of these interventions.
Both the drug and the house-spraying interventions were shown to be safe and highly effective, either on their own or when administered together. Both the drugs and the house-spraying approaches significantly reduced malaria transmission in this low endemic setting.
Why this trial matters
Mass drug administration (MDA) is the administration of antimalarial drugs to target the parasite reservoir in humans, without necessarily testing if those people carry the parasite that causes malaria. The World Health Organization recommends MDA for the elimination of the Plasmodium falciparum malaria parasite. However, the effort and cost required to implement MDA on a large scale can be challenging.
The Namibian study reduced the ‘mass’ in MDA by targeting just the small ring of people around recent index cases – the people at the highest risk of malaria – and thus implemented an existing intervention more efficiently and economically.
Indoor residual spraying (IRS) and the use of long-lasting insecticidal nets have since 2000 significantly reduced malaria cases and deaths in target populations in sub-Saharan Africa. These interventions are normally administered in a ‘blanket’ style before the malaria season (October to May).
The Namibian study targeted a highly effective but expensive insecticide, pirimiphos-methyl, at the small ring of houses around recent index cases. The cost of the insecticide makes it more difficult to use in blanket spraying, but suitable in focal spraying as smaller quantities will be used. The cost of the insecticide is thus offset by its focal use of targeting only high risk populations.
“We found that reactive focal mass drug administration and reactive focal vector control, when implemented alone and in combination, significantly reduced malaria transmission among targeted populations in the Zambezi region of Namibia,” says Koekemoer. “Furthermore, the two interventions, when used in combination, had an additive effect – reducing rates of new malaria cases by 75%”.
Towards zero transmission targets
Although malaria still causes an estimated 230 million cases and over 400 000 deaths each year, dramatic success in fighting the disease over the last two decades has inspired many countries to commit to eliminating transmission altogether.
To date, the World Health Organization has certified 38 countries and territories malaria-free. In southern Africa, eight countries – including South Africa and Namibia – have made the elimination of malaria a policy goal.
In recent years, however, progress towards eliminating transmission has slowed in many regions including Africa, highlighting the need for new approaches. Where malaria cases have been reduced to low levels, transmission still occurs due a reservoir of chronic, low density infections in people without symptoms. This means that these infections are largely undetectable through standard surveillance approaches.
Because the mosquitoes that carry the malaria parasite are still present, these infections may seed further infections in their immediate neighborhood, potentially leading to outbreaks of malaria cases. To prevent such outbreaks from leading to wider epidemics, effective focal responses that target high-risk populations, such as those assessed in the Namibian study, need to be mobilized.
While additional studies will help determine the optimal scenarios in which these approaches could be implemented, the Namibian study suggests that reactive focal mass drug administration and reactive focal vector control can be applied in other countries that (i) have Plasmodium falciparum parasite-carrying mosquitos (ii) are close to eliminating transmission and (iii) have good case reporting systems.
“These approaches can only be used if index cases are promptly and reliably reported and becauseSouth Africa has a responsive and reliable malaria case reporting system, the country is well placed to take advantage of these interventions,” says Koekemoer.
The Namibian study shows how tailoring and targeting existing interventions can help improve their effectiveness and contribute to the elimination of malaria transmission permanently.
I can’t reach with the screwdriver, please pass the laser!
- Wits University
New metasurface laser opens up a new world of applications using optical control of physical objects.
Researchers have demonstrated the world’s first metasurface laser that produces “super-chiral light”: light with ultra-high angular momentum. The light from this laser can be used as a type of “optical spanner” to or for encoding information in optical communications.
“Because light can carry angular momentum, it means that this can be transferred to matter. The more angular momentum light carries, the more it can transfer. So you can think of light as an ‘optical spanner’,” Professor Andrew Forbes from the School of Physics at the University of the Witwatersrand (Wits) in Johannesburg, South Africa, who led the research. “Instead of using a physical spanner to twist things (like screwing nuts), you can now shine light on the nut and it will tighten itself.”
The new laser produces a new high purity “twisted light” not observed from lasers before, including the highest angular momentum reported from a laser. Simultaneously the researchers developed a nano-structured metasurface that has the largest phase gradient ever produced and allows for high power operation in a compact design. The implication is a world-first laser for producing exotic states of twisted structured light, on demand.
Nature Photonics today published online the research that was done as a collaboration betweenWits and the Council for Scientific and Industrial Research (CSIR) in South Africa, Harvard University (USA), the National University of Singapore (Singapore), Vrije Universiteit Brussel (Belgium) and CNST – Fondazione Istituto Italiano di Tecnologia Via Giovanni Pascoli (Italy).
In their paper titled: High-purity orbital angular momentum states from a visible metasurface laser, the researchers demonstrate a new laser to produce any desired chiral state of light, with full control over both angular momentum (AM) components of light, the spin (polarisation) and orbital angular momentum (OAM) of light.
The laser design is made possible by the complete control offered by new nanometer-sized (1000 times smaller than the width of a human hair) metasurface – designed by the Harvard group – within the laser. The metasurface is made up of many tiny rods of nanomaterial, which alters the light as it passes through. The light passes through the metasurface many times, receiving a new twist everytime it does so.
“What makes it special is that to the light, the material has properties impossible to find in Nature, and so is called a “metamaterial” – a make-believe material. Because the structures were so small they appear only on the surface to make a metasurface.”
The result is the generation of new forms of chiral light not observed from lasers until now, and complete control of light’s chirality at the source, closing an open challenge.
“There is a strong drive at the moment to try and control chiral matter with twisted light, and for this to work you need light with a very high twist: super-chiral light,” says Forbes. Various industries and research fields require super-chiral light to improve their processes, including the food, computer and biomedical industries.
“We can use this type of light to drive gears optically where physical mechanical systems would not work, such as in micro-fluidic systems to drive flow,” says Forbes. “Using this example, the goal is to perform medicine on a chip rather than in a large lab, and is popularly called Lab-on-a-Chip. Because everything is small, light is used for the control: to move things around and sort things, such as good and bad cells. Twisted light is used to drive micro-gears to get the flow going, and to mimic centrifuges with light.”
The chiral challenge
“Chirality” is a term often used in chemistry to describe compounds that are found as mirror images of one another. These compounds have a “handedness” and can be thought of as either left- or right-handed. For example, lemon and orange flavours are the same chemical compound, but only differ in their “handedness”.
Light is also is chiral but has two forms: the spin (polarization) and the OAM. Spin AM is similar to planets spinning around their own axis, while OAM is similar to planets orbiting the Sun.
“Controlling light’s chirality at the source is a challenging task and highly topical because of the many applications that require it, from optical control of chiral matter, to metrology, to communications,” says Forbes. “Complete chiral control implies control of the full angular momentum of light, polarisation and OAM.”
Because of design restrictions and implementation impediments, only a very small subset of chiral states has been produced to date. Ingenious schemes have been devised to control the helicity (the combination of spin and linear motion) of OAM beams but they too remain restricted to this symmetric set of modes. It was not possible to write down some desired chiral state of light and have a laser produce it, until now.
Metasurface laser
The laser used a metasurface to imbue light with ultra-high angular momentum, giving it an unprecedented “twist” in its phase while also controlling the polarisation. By arbitrary angular momentum control, the standard spin-orbit symmetry could be broke, for the first laser to produce full angular momentum control of light at the source.
The metasurface was built from carefully crafted nanostructures to produce the desired effect, and is the most extreme OAM structure so far fabricated, with the highest phase gradient yet reported. The nanometre resolution of the metasurface made possible a high-quality vortex with low loss and a high damage threshold, making the laser possible.
The result was a laser that could lase on OAM states of 10 and 100 simultaneously for the highest reported AM from a laser to date. In the special case that the metasurface is set to produce symmetric states, the laser then produces all prior OAM states reported from custom structured light lasers.
Going forward
“What we find particularly exciting is that our approach lends itself to many laser architectures. For instance, we could increase the gain volume and metasurface size to produce a bulk laser for high-power, or we could shrink the system down onto a chip using a monolithic metasurface design,” says Forbes.
“In both cases the lasing mode would be controlled by the pump’s polarisation, requiring no intra-cavity elements other than the metasurface itself. Our work represents an important step towards merging the research in bulk lasers with that of on-chip devices.”
Background information
South Africa’s laser history dates back to soon after the very invention of the laser itself, then at the CSIR’s National Physical Laboratory. It continues today with seminal advances from Prof. Forbes and his team, including the world’s first digital laser in 2013, the first twisted light laser in 2016 and now the first super-chiral laser.
This laser demonstration follows on the heels of the 2019 demonstration of the first Fractal light from lasers. The latter work, also performed by PhD student Hend Sroor, made international news and was selected by the OSA as one of the top 30 optical advances worldwide in 2019.
The Structured Light Laboratory at Wits, led by Prof. Andrew Forbes, has three main focus areas: structured light lasers, quantum structured light, and classical structured light. The team develop toolkits for the creation, manipulation and detection of exotic states of light, as well as applications of structured light in optical communication, metrology, imaging and security.
Wits publishes first clinical data on COVID-19 in South Africa
- Wits University
Health professionals will face difficult ethical decisions when it comes to dealing with COVID-19 patients.
For example, do they resuscitate patients even though the prospects of recovery are slim and the risk to the healthcare team high? How should healthcare workers respond?
This is one of the topics covered in the COVID-19 Special Issue of the Wits Journal of Clinical Medicine. The journal, published by Wits University Press under open access conditions, presents the first clinical data on COVID-19 published in South Africa.
The special issue covers a range of aspects of the pandemic, from the clinical, through ethical, to the social dynamics of its impact.
Editor-in-chief of the Wits Journal of Clinical Medicine Professor Pravin Manga says it is important for health professionals and the public to have access to scientific information: “Social media is awash with all sorts of quackery regarding prevention and treatment remedies for COVID-19 and it is during these times that we need to be rational and be guided by science rather than by emotion.” Manga is Professor of Internal Medicine, School of Clinical Medicine, in the Faculty of Health Sciences at Wits.
In addition to being a public resource, more than 10 articles in this issue aim to guide healthcare workers. These address the ethical aspects related to the pandemic – which patients should healthcare workers admit to already-filled intensive care units and who decides this? Associate Professor Kevin Behrens, Director and Head of the Steve Biko Centre for Bioethics discusses such ethical conundrums in his review.
*足球竞彩app排名 Resources for Academics and 足球竞彩app排名s: Access the entire Wits University Press eBook collection in your university library through JSTOR and Proquest until 1 July 2020.
Coronavirus: why South Africa needs a wealth tax now
- Aroop Chatterjee, Amory Gethin and Léo Czajka
A wealth tax on the top 1% of South Africans could raise R143 billion. This corresponds to 29% of the R500 billion COVID-19 package announced by the government.
The consequences of the COVID-19 lockdown are yet to be fully determined and understood. But one thing we can be fairly certain of – in South Africa its impact will be shaped by the country’s inequalities.
Our study reveals that half of the adult population survives with near-zero savings, while 3,500 individuals own 15% of the country’s wealth. The response to the crisis must take this into account to help the most vulnerable while still safeguarding fiscal sustainability.
Based on our new study on wealth inequality in South Africa, we propose a progressive solidarity wealth tax. This would allocate the fiscal burden of current interventions on those most capable of paying. It is in line with the recommendations recently made by the International Monetary Fund to equitably attain fiscal sustainability and better position the economy for post-COVID recovery.
We show that a wealth tax on the richest 354,000 individuals could raise at least R143 billion. That equates to 29% of the announced R500bn fiscal cost of the relief package.
Unequal distribution
A lot of studies show how extreme income inequality is in South Africa, but little has been documented about wealth. Net wealth is the sum of all assets less any debts. Assets include cash, bank deposits, pensions, life insurance, property, bonds and stocks. Debt includes mortgages and other loans such as retail store credit accounts or loans from friends, family and money lenders.
In our new paper, we combine national accounts statistics, household surveys and exhaustive tax microdata to assess the reliability of available data sources. We also provide the most comprehensive possible picture of the distribution of wealth. This is the first time this has been done in South Africa.
Better data is needed – about direct ownership, capital income and assets held through trusts. Nevertheless, our results give a good sense of the magnitude of the disparities. Three key results are worth mentioning.
Firstly, in 2017, the 10% richest South Africans (all adults with a net worth over R496,000) owned 86% of wealth, with an average of R2.8 million per adult. In contrast, about 18 million (the poorest 50%) were either in debt or had near-zero savings. With an average net worth of R486 million, the richest 3,500 owned 15% of wealth. This was more than the 32 million poorest altogether.
Secondly, these extreme inequalities extended to all forms of assets. The richest 10% owned 99.8% of bonds and stock – which accounted for 35% of wealth. The top decile also owned 60% of housing wealth and 64% of pension assets. Housing wealth amounted to 29% of wealth and pension assets to 33%.
Thirdly, we show that wealth concentration has remained broadly stable since 1993, and may even have increased within top wealth groups. Wealth inequality remains significantly higher than what could be estimated in Russia, China, India, the US or France.
Why wealth inequality matters now more than ever
Our findings are particularly relevant to the current crisis. South Africans are unequally armed to survive the contraction of the economy produced by the lockdown. Our paper helps get a sense of the size of the population likely to be under intense stress in the very short term.
Before the lockdown, about half of the population was already in debt, or had near-zero net wealth. Therefore, this crisis will at best sink millions of people further into indebtedness or force them to beg, loot or starve. Conversely, our paper shows that a minority of individuals are in a much less vulnerable situation.
The policy solutions needed to absorb the shock and recover fast must be carefully designed to take these factors into account. Principally, they need to reallocate resources to give everybody equal chances to survive the shock.
In this unprecedented crisis, the government announced a relief package with a R500 billion fiscal cost. One key remaining question is how such a plan will be funded.
The possibility of collecting additional tax revenue from those most able to contribute has not yet been brought to the table. We believe it should be considered. Our estimation suggests it would raise significant revenues. And it would allow the country to allocate the cost of the national response on the least vulnerable.
In the spirit of solidarity, a wealth tax could be part of the solution to safeguard long-run fiscal sustainability and inclusive growth.
How much could a wealth tax raise?
We propose a progressive wealth tax, which would apply only to South Africans with a net wealth currently superior to R3.6 million, that is the richest 354,000 (1% of the adult population).
The first bracket – all wealth between R3.6 million and R27 million – would be taxed at a 3% rate, the second bracket (R27 million to R119 million) at 5%, and all wealth above R119 million at 7%. Individuals with less than R3.6 million would be exempt. A billionaire would face a 6.7% tax rate: she would pay 3% on the fraction of her wealth higher than R3.6 million but lower than R27 million; 5% on wealth higher than R27 million but lower than R119 million; and 7% of the R821 million she owns above R119 million. This would leave her with post-tax wealth of R933 million.
Other tax schedules could of course be designed. The objective here is to give an order of magnitude of the expected revenues.
Taking into account the recent Johannesburg Stock Exchange All Share Index drop in value and assuming a 30% evasion rate (as available evidence suggests), we simulate that such tax would raise R143 billion.
It would still leave rich individuals with very high levels of wealth: for each of the brackets, post-tax wealth would on average be R9.3 million, R50 million and R376 million respectively.
A realistic policy
Critics of a wealth tax argue that it would be too costly and complex to implement. But South Africa is well positioned to administer this tax cost-effectively.
Firstly, the tax base we consider covers very few individuals, reducing the administration required.
Secondly, South Africa already has in place third-party reporting by financial intermediaries straight into the South African Revenue Service, providing information on capital income and ownership. Existing municipal valuations could be used to value property assets. This would cover the major components of asset holdings, especially stocks and bonds.
Capital flight, through offshoring or migration, is a potential risk. We account for this by making conservative assumptions about avoidance and evasion, and still project sizeable revenues. There is also markedly more cooperation between tax authorities to clamp down on undeclared incomes and assets in foreign jurisdictions, including tax havens. The premise is not a given. Capital flight implies forfeiting opportunities that considerably enriched them for the sake of avoiding a tax that barely makes an impact on their total wealth. 足球竞彩app排名ly, the wealthy themselves have said now is the time for solidarity.
A wealth tax, contrary to popular opinion, would not necessarily discourage job-creating investments. Maintaining fiscal sustainability while sparing the most vulnerable is more important to ensure a quick recovery and attract investments. Moreover, inherited wealth has a significant role in South Africa: we find high levels of wealth concentration even among 20-year-olds. Diminishing the importance of inherited capital with a wealth tax may actually be a better collective strategy to improve social welfare, including growth.
In light of the lessons learned from the Zondo commission of inquiry into corruption, taxpayers would need guarantees that this special tax will be properly collected and spent. The national treasury already uses ringfencing mechanisms to make revenue and spending for specific projects accountable. To answer potential criticism, the government could build on such rules to generalise more transparent practices.
There may be theoretical implementation challenges of such a wealth tax. But we would argue that South Africa is well placed to overcome these.
When designing the radar for Britain during World War II, Robert Watson-Watt justified his choice of a nonoptimal frequency as follows:
Give them the third best to go on with; the second best comes too late, the best never comes.
This radar was pivotal in allowing Britain to overcome a larger, more sophisticated German air force.
In our situation, we cannot let perfection be the enemy of progress, or in this case, survival.
Aroop Chatterjee, Research Manager: Wealth Inequality, Southern Centre for Inequality Studies, University of the Witwatersrand; Amory Gethin, Research Fellow - World Inequality Lab - Paris School of Economics, and Léo Czajka, Research fellow - World Inequality Lab - UCLouvain
Professor Lee Berger introduces one of the world's longest running and richest fossil hominid sites.
One of the richest fossil hominid sites in the World, and one of the longest running excavations, Sterkfontein is famous worldwide for discoveries such as Mrs. Ples, Stw 505 and Little Foot. The richest area for fossil hominids at Sterkfontein is Member 4, where, since 1966 excavations have produced more than 600 individual fossil hominid remains. Some of these remains are beautifully preserved and represent the best examples of the extinct hominid species Australopithecus africanus.
Exploring the Fossil Hominid Vault at the University of the Witwatersrand
- Wits University
Professor Lee Berger shows what is behind the doors of the Phillip V Tobias Fossil Hominid vault.
The Fossil Primate and Hominid Vault in the Evolutionary Studies Institute at the University of the Witwatersrand houses perhaps the largest collection of fossil hominid remains in the world.With over 3500 individual fossils, a large comparative cast collection and a significant assemblage of non-human fossil primates, the vault is a mecca for scientists from around the world.The world-class facility was purpose built seven years ago and can support more than 30 scientists at a time working on its collections.It is situated next to a dedicated Micro-CT scanning facility dedicated to scanning heritage remains.
Wits needs 300 volunteers for COVID-19 rapid test study
- Wits University
Have you tested positive for coronavirus or been near someone who has? If so, your country urgently needs you for a South African COVID-19 rapid test study.
This study, led by the Wits Department of Immunology, aims to ensure that existing rapid tests for COVID-19 are accurate.
Qualifying volunteers will need to submit blood and saliva samples for serological testing for COVID-19. This includes the rapid antibody tests and the formal serology assays. [An assay is a laboratory procedure to measure quantities].
Serological tests measure the amount of antibodies or proteins present in the blood when the body is responding to a specific infection (such as COVID-19).
Antibody tests check for the small molecules that the body produces to fight infection. These antibodies are very specific to particular infections and form the basis of serology testing for many infectious diseases.
Why this study is important
South Africa urgently needs to increase testing for COVID-19 so that infection can be identified, traced, isolated and contained. Although a number of rapid diagnosis tests are already available in South Africa, they are not consistently reliable. Inaccurate test results could lead people to believe they do not have the coronavirus, so they don’t self-isolate and then inadvertently infect others.
“Although there are rapid diagnostic tests available that can test for antibodies in the blood and deliver a result within minutes, these tests have not performed consistently well,” says Professor Elizabeth Mayne, Head of the Division of Immunology at Wits and Principal Investigator for this study.
“To check that the various rapid tests being brought into South Africa work, we need blood and saliva samples from 300 people who tested positive for coronavirus, or who were in close contact with someone who tested positive".
The role of volunteers
On volunteering for the study, you will be briefed fully and will have the opportunity to ask questions.
You will be asked questions about your age, any underlying conditions you might have, such as high blood pressure and chronic lung diseases, any medications being taken, when you tested positive, your travel history and whether or not you had any symptoms.
A nurse will be dispatched to your home. The nurse, wearing full personal protective equipment (PPE), will extract around eight teaspoons of blood from you, as well as some saliva and some mouth/throat swabs.
These bio-samples of your blood and saliva will be used to create banks of known positive and negative controls, which scientists around the country can use to quickly and accurately evaluate any rapid or serological tests.
足球竞彩app排名 the study
The study is approved by the Human Research Ethics Committee at Wits University.
A minimum of 300 participants are required for the study.
The study is ongoing, so participants can volunteer at any time.
Participation is entirely voluntary and participants can withdraw consent at any time without giving a reason. Such withdrawal will have no effect on participants' diagnosis or treatment.
Participants will not be paid or in any way be financially remunerated for participating.
Participants will not be able to get the results of their tests.
How to volunteer
If you meet the criteria and wish to participate please email Elizabeth.mayne@nhls.ac.za or call 082 337 6349 for a comprehensive briefing and enrolment.
足球竞彩app排名 the Principal Investigator
Professor Elizabeth Mayne holds an MBBCh and MMED in haematology from Wits University. She is a specialist haematopathologist has since 2018 been Head of Immunology in the School of Pathology in the Faculty of Health Sciences at Wits. She is collaborating with Professor Wendy Stevens and Professor Ian Sanne on this project.
Choices in a fog of uncertainty: lessons for coronavirus from climate change
- Robert (Bob) Scholes, Albertus J. Smit, Francois Alwyn Engelbrecht, Guy Franklin Midgley, Jennifer Fitchett, Neville Sweijd, Pedro M.S. Monteiro and Pravesh Debba
The science to policy process that was developed to guide climate mitigation decisions can be applied to the response to the COVID-19 pandemic.
Governments around the world, driven by the threat of overburdened health systems and mass mortality resulting from the COVID-19 pandemic, are being forced to make decisions that have enormous, long-lasting consequences for lives and economies. They are doing so without sufficient assurance that the choices they make are the best ones.
The fog of uncertainty can be partly lifted by better use of information that’s emerging around the world. But it will never completely clear.
The most difficult choices are those that have to be made before you know how they will work out.
The challenge of making high-consequence decisions based on imperfect knowledge is not unprecedented. For example, tough policies to mitigate climate change must be adopted long before the world crosses catastrophic thresholds. To guide these decisions, countries rely on imperfect models of the climate system, along with divergent and values-based assumptions about how the future could unfold.
Scientists and policymakers, working together over a period of three decades through the Intergovernmental Panel on Climate Change, have worked out how to guide decisions in the face of uncertainty in such a way that there is broad agreement, and which minimises regrets even if the future does not work out exactly as projected. Their approach has allowed scientists to remain providers of evidence, and politicians to focus on value-based choices.
The Paris Agreement to mitigate climate change, signed by 197 countries, was the result of a well-functioning science-policy interaction.
This experience can be applied to the response to the COVID-19 pandemic, without having to reinvent the process.
The best practice guidelines involve making decisions based on the best available information at the time, and progressively improving them in the light of experience and emerging new information. Secondly, they involve using a “multi-model approach” and an ensemble of results, rather than placing all bets on a single prediction. And finally, they use collectively agreed scenarios to explore the full range of options and outcomes.
Three-pronged approach
Decisions about containing COVID-19 are inevitably a balancing act between reducing the immediate loss of lives on the one hand, and protecting livelihoods that could be damaged as a result of the actions taken on the other. The models used to support the decisions must be similarly balanced. There is no point in having precise projections about the course of the pandemic, but only a vague idea of the impact on the economy.
At present, these different streams of information are not well integrated.
For the case of using mathematical models to help guide COVID-19 policies, we make the following suggestions based on our collective experience with scientific assessments.
Use what information is available, then adapt: The novelty of the disease means you start from knowing very little and taking guidance from experiences with similar diseases in the past. You work towards improving modelled projections, using information from a range of sources – from science to public health to the economy.
Nimble and efficient channels of communication ensure that the pace of modelling matches the urgency of the problem.
The multi-model approach: Using several different models rather than one relies on the same logic that tells you not to put all your savings into a single asset. The most robust approach is to build a portfolio, which is collectively stronger than just one, particularly if they are based on fundamentally different assumptions.
Typically, different models have different purposes, and some are stronger in some respects than others. Some models are good at short-term projections while others are better in the long term. Including more detail is necessary for some purposes, but a less detailed model may be sufficient, and more reliable, for more general policies.
This does not mean you should not winnow out models that are simply wrong. But to do so you need a well-structured, evidence-based test. The statistician George Box wisely commented that “all models are wrong, but some are useful”.
For modelling COVID-19 we would similarly encourage a diversity of models.
Scenarios: Some things cannot be predicted accurately, because they depend on chaotic physical processes, or behaviours that defy simple representation, such as human choices. For these issues you use scenarios. Scenarios allow the models to be stress-tested, by asking questions such as: What is the range of possible outcomes? How does my decision play out in the worst case, as well as in my preferred case?
The scenarios must be shared between models, or you are unable to tease apart differences in the way models work from differences in model drivers.
The scenarios need to be plausible, but must span a wide range of possibilities if they are not to lead to confirmation bias – our tendency to choose the outcomes that support our prejudices. It is important to include measurable indicators, so that you later know which scenario is playing out.
For COVID-19 we recommend exploring the model predictions over a range of agreed scenarios. For example, one scenario can impose strict lockdown and maintain it over several months. Another can progressively relax the restrictions. And both can be compared to a reference scenario where no policy action is taken.
When many models, several scenarios and uncertain data are used together, the result will be a wide range of predictions. The differences need to be evaluated so it’s clearer which findings have the most supporting evidence.
Public trust is key
The balancing act of managing COVID-19 requires public trust, which is fostered by an open, clear and credible process of decision-making. The framework we propose is focused on providing the information needed to make good decisions, but should not assume the right to make the decisions. For that purpose, people elect political leaders to represent their rights and values.
This approach has been successfully applied elsewhere, for instance in the protection of the ozone layer, and mobilising action to halt biodiversity loss. In South Africa, it recently aided sensible decisions regarding fracking in the Karoo.
Seeing serious problems with both these approaches, Latypov and his colleague Dr Sofya Chistyakova, also from the Wits School of Geosciences, found that there is actually a simple explanation to this question – and it has nothing to do with the mechanical sorting or mixing of minerals to produce these rocks.
The Journal of Optics is the official journal of the European Optical Society and is published by the UK’s Institute of Physics (IoP). 
Among their other interesting findings, Chapelle found that each embryo had two types of teeth preserved in its developing jaws. One set was made up of very simple triangular teeth that would have been resorbed or shed before hatching, just like geckos and crocodiles today. The second set was very similar to that of adults, and would be the one that the embryos hatch with.
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The grant award supports COVID-19-related visualisation and analytics for Southern Africa. The nature of the project is interdisciplinary, where medical data and expertise need to be combined with the wealth of methodologies and algorithms used in advanced analytics, Big Data and Data Science. Assumptions used in the project revolve around our current level of understanding of advanced analytics driven by Data Science and other disciplines. Both main-stream statistical frameworks, frequentist and Bayesian are an underlying assumption to model development. Input from the different medical, virology and custodians of static data pertaining to populations, social and medical vulnerabilities, access to medical infrastructure, prevalence of various relevant pre-existing conditions are also underlying assumptions. 
