Philippine President Rodrigo Duterte is under quarantine after being exposed to a household staff member who tested positive for Covid-19, his spokesman said on Thursday.
Duterte, 76, has since tested negative for Covid-19, but is “currently observing mandatory quarantine protocols,” presidential spokesman Karlo Nograles said.
Some 30,000 Russian combat troops are expected to amass in Belarus in the coming weeks, NATO Secretary General Jens Stoltenberg said on Thursday, expressing concern about the build-up of Moscow's military presence on Ukraine's doorstep.
"This is the biggest Russian deployment there since the Cold War," Stoltenberg said in Brussels, adding that combat aircraft, nuclear-capable Iskander missiles, S-400 air defence systems and special units of the military intelligence agency GRU were involved in the build up.
But microdosing may offer more beyond its mood-boosting abilities.
Using zebrafish and our new method for precise and repeated drug administration, my colleagues and I are studying LSD and terpenes (chemicals in plants responsible for their scent, among other things) in a series of projects exploring potential novel treatments for mental illness and alcohol use disorder.
Zebrafish might seem an odd choice in studying human health, but they share 70 per cent of their genes with us and are a popular nonhuman organism used by scientists to study biological processes. They are also incredibly social, making them well-suited for behavioural studies into psychiatric disorders and drug discovery.
However, past drug research using zebrafish has studied “chronic” administration — putting fish in a drug solution for weeks. Since humans require (at the very least) some sleep, this administration can’t accurately reflect human consumption patterns.
To address this limitation, we developed a new method to dose multiple fish accurately and efficiently for exact exposure times. By placing an insert into the housing tank, we can move groups of fish from their housing tank into a dosing tank for a precise dosing period, more closely mimicking the way that a person might consume drugs or alcohol.
To verify that this new dosing procedure could have behavioural and neurochemical effects, we completed a series of projects using our new method to examine the effects of alcohol and nicotine.
First, we tested the zebrafish with a daily moderate dose or a weekly binge-level dose of ethanol for three weeks. We found a significant difference in location preference in the daily moderate group compared to controls during a withdrawal period, which implies there were neurological changes.
Then we followed up with a study using lower doses for shorter periods of time. Here, we saw decreased boldness and increased anxiety-like behaviour during withdrawal from the highest dose (opposite to what is seen after an acute single-dose).
Similarly, testing the model using nicotine, we found again that acute doses decreased anxiety-like behaviour while repeated dosing led to an increase of anxiety-like behaviour during withdrawal.
For humans, having an alcoholic drink or a cigarette can decrease anxiety, and the inverse is observed in withdrawal. Our zebrafish model is consistent with this, which has given us confidence that we can test novel compounds with potential therapeutic effects in humans.
Researchers have been finding that cigarette and alcohol consumption has increased during the pandemic. These substances can reduce anxiety, but withdrawal from them can increase it.
(Shutterstock)
Terpenes are a large and diverse group of aromatic compounds. They are responsible for the smell, taste and pigmentation of plants. Many terpenes — like those found in tea, lemongrass, cannabis and citrus fruits — have medical benefits.
We found that zebrafish acutely dosed with the terpene limonene (found in citrus fruit peels and cannabis) and myrcene (found in cannabis and hops), showed a significant reduction in anxiety-like behaviour. One observation that may be clinically significant is that — contrary to nicotine or alcohol — no negative effects were seen after repeated dosing for seven days, suggesting minimal to no addictive potential.
This study, alongside previous research, suggests that the terpenes limonene and beta-myrcene possess sedative and anti-anxiety effects that have potential as valuable therapeutic compounds for the treatment of a variety of mental health conditions.
There is a growing interest in microdosing psychedelics to increase productivity and spark creativity.
(Shutterstock)
Some of the most influential research into psychedelics began in Saskatchewan in the 1950s. British-born psychiatrist Humphry Osmond used LSD and mescaline to treat alcoholism, with single doses showing a 50 to 90 per cent recovery rate over two years.
However, while Osmond saw success in large single-dose treatments, the acute administrations required continuous monitoring of the patient over the seven- to 15-hour “trip” to prevent any harm arising from impaired judgment. From a therapeutic perspective, this would be very time-intensive for clinicians, and is not feasible.
This is where microdosing comes in. With the potential to be easy and safe, we believe this pattern of exposure to be more therapeutically relevant, as doses are small enough to be safely self-administered with the proper guidance of a clinician.
In our first study, we repeatedly microdosed our zebrafish with LSD. Using behavioural neuroscience tests to quantify locomotion, boldness and anxiety-like behaviour, we observed no impact on behaviour after 10 days of repeated dosing. Like with terpenes, this may suggest a lack of withdrawal symptoms or addictive potential, which is encouraging for clinically viability for use in humans.
Our current study examines the effects of LSD microdosing on the symptoms of alcohol withdrawal, which is a growing issue in Canadian health care.
In Canada, the negative effects of alcohol are widely felt. Fetal alcohol spectrum disorder remains the leading developmental disability in Canada, and alcohol harm is a top cause of injury and death. It costs Canadians billions of dollars in lost productivity, and is a burden on the health-care and judicial systems. Treatment and rehabilitation can be costly, time consuming and bogged down in lengthy wait times — if accessible at all.
Further research into other psychedelics, like psilocin (the psychoactive compound in psilocybin, or “magic mushrooms”), are also planned with the goal of providing scientific evidence to help determine whether these substances should be used in larger clinical trials in humans.
Psychedelics may provide assistance, but despite increasing evidence that LSD and psilocin are non-addictive and low risk, they remain highly restricted. Perhaps with more research and the continuing shift in public perception, we might yet again see LSD being used as a radical treatment for mental health and addiction.
Trevor James Hamilton, Associate Professor in Neuroscience (Department of Psychology), MacEwan University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
No further fossilised human tracks have been discovered in the area since then – but a recent find by our research team, also near Langebaan, changes this.
These two tracks, discovered in what is today the ceiling of a small cave, are a remarkable find for three reasons. The first is that modern graffiti on aeolianite surfaces in the area around Langebaan area is prolific. In fact, graffiti was present just inches away from “Eve’s footprints”. A potential fossilised human tracksite on the Cape south coast near Knysna, more than 400 km to the east, was defaced by graffiti before it could be scientifically assessed.
We don’t know precisely when this happened, but we know that the graffiti “artists” got to it before we did. It is therefore possible that fossil tracksites around Langebaan are rare because graffiti has obscured them.
The second reason is that human tracks registered in aeolianites are rare at a global level. The majority of such tracks are found in cave floor deposits or volcanic ash sediments; the South African sites, which were made on dunes and beaches, are an exception. And the third is that our find, made within kilometres of those Roberts discovered in 1995, supports his conclusion that a human ancestor left “Eve’s footprints”.
Rudolf Hattingh, a speleologist – he studies caves – and member of our research team, found the two tracks on the small cave’s ceiling while out exploring for caves.
They are natural casts, representing the sediment which filled in the original tracks. The original dune surface on which the tracks were made has been eroded away, and is no longer evident. They are probably of approximately the same age as “Eve’s Footprints”, and therefore from the Late Pleistocene epoch, which began about 126,000 years ago.
Graffiti in aeolianites at Langebaan. Some potential human tracks have been destroyed by such graffiti.
CHARLES HELM
The two tracks have approximately the same orientation, and are are an appropriate distance apart (49 cm) for a walking human, which suggests that they form a short trackway segment. They are friable, vulnerable even to light touch, and their margins are not crisply defined – it is possible that more detail might have been present if they had been discovered earlier.
Track length is approximately 28 cm (although this may include a heel drag), width is 13 cm, and depth is 3-4 cm. One of the tracks contains a possible outline of a hallux (big toe). Both tracks show an outward convexity, suggesting the presence of a medial arch. These features are all broadly consistent with a human trackmaker walking on a dry, non-cohesive dune surface.
We would have preferred a longer trackway and tracks which showed more anatomical detail morphology. Nonetheless, the identification of new probable human tracks at Langebaan, free of graffiti, is still a significant find. Although extinct members of our genus like Homo naledi and Homo helmei cannot be completely excluded, we believe the likelihood is that these tracks, like “Eve’s Footprints”, were made by one of our direct Homo sapiens ancestors.
Although the focus of our work is on the Cape south coast, not the west coast, this discovery is a spur to keep exploring in the Langebaan area, especially in the few remaining areas that are free of graffiti.
It also inspires us to be vigilant for cliff-collapse events which may create new aeolianite exposures on this coastline. Fossil tracks are evocative: they can readily transport us back in time and lead us to think what it must have been like to walk on a dune more than 100,000 years ago, near what is today known as Langebaan.
Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
I am a paleontologist, and the debate sparked by my 2015 paper has made me reconsider how researchers studying ancient animals use statistics.
The limited fossil record makes it hard to declare if a dinosaur was sexually dimorphic. But I and some others in my field are beginning to shift away from traditional black-or-white statistical thinking that relies on p-values and statistical significance to define a true finding. Instead of only looking for yes or no answers, we are beginning to consider the estimated magnitude of sexual variation in a species, the degree of uncertainty in that estimate and how these measures compare to other species. This approach offers a more nuanced analysis to challenging questions in paleontology as well as many other fields of science.
In many species, like these mandarin ducks, males (left) and females (right) look very different.
Francis C. Franklin via WikimediaCommons, CC BY-SA
Sexual dimorphism is when males and females of a certain species differ on average in a particular trait – not including their reproductive anatomy. Classic examples are how male deer have antlers and male peacocks have flashy tail feathers, while the females lack these traits.
Dimorphism can also be subtle and unflashy. Often the difference is one of degree, like differences in the average body size between males and females – as in gorillas. In these modest cases, researchers use statistics to determine whether a trait differs on average between males and females.
Studying sexual dimorphism in extinct animals is fraught with uncertainty. If you and I independently dig up similar fossils of the same species, they are inevitably going to be slightly different. These differences could be due to sex, but they could also be driven by age – young birds are fuzzy, adult birds are sleek. They could also be due to genetics unrelated to sex, like eye color in humans.
It’s possible that variation among individual dinosaurs of the same species could be due to sexual dimorphism, but there are rarely good enough samples to assert so using traditional statistics.
James Ormiston, CC BY-ND
If paleontologists had thousands of fossils to study of every species, the many sources of biological variation wouldn’t matter as much. Unfortunately, the ravages of time have left the fossil record painfully incomplete, often with less than a dozen good specimens for large, extinct vertebrate species. Additionally, there is currently no way to identify the sex of an individual fossil except in rare cases where obvious clues exist, like eggs preserved within the body cavity.
So where does all this leave the debate on whether male and female dinosaurs had differences within traits? On the one hand, birds – which are direct descendants of dinosaurs – commonly show sexual dimorphism. So do crocodilians, dinosaurs’ next closest living relatives. Evolutionary theory also predicts that, since dinosaurs reproduced with sperm and egg, there would be a benefit to sexual dimorphism.
These things all suggest that dinosaurs likely were sexually dimorphic. But in science you need to be quantitative. The challenge is that there is little in the way of statistically significant analyses of the fossil record to support dimorphism.
Very large sex differences can create a bimodal distribution that looks like two distinct groupings of a certain measurement.
Maksim via WikimediaCommons, CC BY
There are a couple of ways paleontologists could test for sexual dimorphism. They could look to see if there are statistically significant differences between fossils from presumed males and females, but there are very few specimens where researchers know the sex. Another method is to see whether there are two distinct groupings of a trait, called a bimodal distribution, which could suggest a difference between males and females.
To tell whether a perceived difference between two groups is true, scientists have traditionally used a tool called the p-value. P-values quantify the probability of a result being due to random chance. If a p-value is low enough, the result is deemed “statistically significant” and considered unlikely to have happened by chance.
But p-values can be heavily influenced by sample size and the design of the study, in addition to the actual degree of sexual dimorphism. Because of the very small sample size of fossils, relying on this statistical technique makes it exceedingly difficult to categorically proclaim what dinosaur species were dimorphic.
The weakness of the black-or-white approach that focuses solely on whether a result is statistically significant has led to hundreds of scientists calling to abandon significance testing with p-values in favor of something called effect size statistics. Using this approach, researchers would simply report the measured difference between two groups and the uncertainty in that measurement.
I have begun to apply effect size statistics in my research on dinosaurs. My colleagues and I compared sexual dimorphism in body size between three different dinosaurs: the duck-billed Maiasaura, Tyrannosaurus rex and Psittacosaurus, a small relative of Triceratops. None of these species would be expected to show statistically significant size differences between males and females according to p-values. But that approach does not capture the nature of the variation within these species.
Using effect size statistics, researchers were able to determine that the duck-billed dinosaur Maiasaura showed a larger amount of dimorphism with the least uncertainty in that estimate compared to other dinosaurs.
When we instead used effect size statistics, we were able to estimate that male and female Maiasaura demonstrate a greater difference in body mass compared to the other two species and that we had a higher confidence in this estimate as well. A few of the characteristics within the data helped reduce the uncertainty. First, we had a large number of Maiasaura fossils, from individuals of various ages. These bones very nicely fit with trajectories of how size changes as an individual grows from juvenile to adult, so we could control for differences due to age and instead focus on differences due to sex.
Additionally, the Maiasaura fossils all come from a single bone bed of individuals that died in the same place at the same time. This means that variation between individuals is likely not due to them being different species from different regions or time periods.
If my colleagues and I had approached the problem expecting a yes or no answer on whether males and females differed in size, we would have completely missed all of these intricacies. Effect size statistics allow researchers to produce much more nuanced and, I think, informative results. It is almost as much a difference in the philosophical approach to science as it is a mathematical one.
Studying dinosaur dimorphism is not the only place p-values create issues. Many fields of science, including medicine and psychology, are having similar debates about issues in statistics and a worrying problem of unrepeatable studies.
Embracing uncertainty in data – rather than looking for black-or-white answers to questions like whether male and female dinosaurs were sexually dimorphic – can help elucidate dinosaur biology. But this shift in thinking may be felt far and wide across the sciences. A careful consideration of problems within statistics could have deep impacts across many fields.
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Evan Thomas Saitta, Postdoctoral Scholar in Paleontology, University of Chicago
This article is republished from The Conversation under a Creative Commons license. Read the original article.
