Connect with us

Science

Plague transmission rates increased from the Black Death to the Great Plague

Published

on

Oct. 19 (UPI) — From the 14th to the 19th centuries, Europe and Asia were struck by successive waves of the plague. New research — published Monday in the journal PNAS — suggests that over the course of the pandemic, from the Black Death of 1348 to the Great Plague of 1665, transmission rates increased four-fold.

In recent years, genomic analysis has offered scientists a variety of insights into the nature of bubonic plagues that decimated much of Europe and Asia during the Late Middle Ages, but details related to disease transmission mode and dynamics have been hard to come by.

Plague is caused by the bacterium Yersinia pestis, which can be transmitted via flea bites, the typical route for bubonic plague, or directly from human to human, called pneumonic plague.

“Both types of transmission can occur during a given epidemic, but which type of transmission seems most likely in various times and places, and why, is often debated,” lead study author David Earn, a researcher in mathematical epidemiology at McMaster University in Canada, told UPI in an email.

By studying a variety of historical, demographic and epidemiological data, Earn and his colleagues were able to show that transmission steadily increased over the course of the epidemics that struck London between the 14th and 19th centuries.

The data also showed that pneumonic transmission could not have been the primary mode of transmission during the 14th century in London.

Scientists relied on three main sources of data: weekly all-cause mortality totals from parish registers, beginning in 1538, when deaths were first registered; weekly mortality from plague, recorded in the London Bills of Mortality; and last wills and testaments, dated to the day, running from 1340 to 1680.

Researchers used the mortality data to estimate transmission rates of each successive epidemic. The research team also ran models to estimate mortality totals had the early waves been driven primarily by human-to-human transmission.

“In this scenario of purely pneumonic transmission, we found that at most 15 recent of the population would have died from plague,” Earn said. “But estimates of the mortality toll during the Black Death in 1348 are at least 30 percent of the population. This inconsistency makes purely pneumonic transmission in the 14th century implausible.”

Earn and his colleagues suspect both climate and shifting population densities played a role in accelerating transmission rates during the later waves of the plague.

“Evidence has accumulated over the last 15 years or so that humidity affects influenza transmission, and it is reasonable to imagine that climate might affect plague transmission,” Earn said.

In followup studies, researchers plan to investigate the effects of climate, population density, social structure and genetic changes on the transmissibility of plague and the primary transmission mode during the 16th and 17th centuries.



Source link

Continue Reading
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *

Science

Fight judges favor aggression over skill, study shows

Published

on

Oct. 28 (UPI) — Often to the chagrin of fans and competitors, wrestling matches, boxing bouts, mixed martial arts and other types of combat competitions are frequently decided by judges.

That’s bad news for competitors that rely more on skill than vigor. New research suggests judges are more likely to award victory to aggressive fighters than skilled fighters, all else being equal.

For the study, published this week in the journal Biology Letters, researchers analyzed data collected from 550 men’s and women’s mixed martial arts contests organized by the Ultimate Fighting Championship.

The data included the percentage of strikes that landed firmly and accurately, a measure of skill, as well as the number of strikes attempted per second, a measure of vigor or aggression.

Regardless of the match conclusion, whether decided by knockout or judges’ decision, the data showed the victor was the more vigorous fighter. However, the correlation between vigor and victory was strongest for matches decided by the scores of the judges.

Fighting skillfully wasn’t entirely discounted. The data showed addition of skill enhanced the advantage of vigor, but the research showed vigor was the most important factor for fights decided by the judges.

“MMA is a fast paced sport and one of the suggestions from our research would be that judges may find vigor easier to assess than skill,” lead author Sarah Lane, postdoctoral research fellow at the University of Plymouth, said in a news release. “That, in turn, leads them to overvalue it when making their decisions, especially in longer fights where one fighter tires more quickly and the disparity in vigor is easier to spot.”

“The advance of technology such as instant replays could potentially counter this, but until they are employed more regularly rate of attack is likely to remain the most important performance trait for victory by decision,” Lane said.

The research was funded by the Biotechnology and Biological Sciences Research Council, which supports studies focused on the role of skill in animal contests.

Most of Lane’s time is spent studying hermit crab fighting, but the authors of the latest paper suggest their analysis of human fights could have implications for understanding physical competitions among animals.

There aren’t typically knockouts in fights between rival animals. Often, males joust and tussle to demonstrate their physical dominance to would be rivals and mates. Like in boxing, a competitor’s performance is subjective.

“Human combat sports provide a unique scenario in which to explore how performance traits such as skill and vigor are perceived, both by participants and observers,” said study co-author Mark Briffa.

“However, because of the obvious communication issues, very little is known about the accuracy with which fighting animals more widely judge the abilities of their rivals,” said Briffa, a professor of animal behavior at Plymouth.



Source link

Continue Reading

Science

Graphene-based memory resistors could pave the way for brain-based computing

Published

on

Oct. 29 (UPI) — Researchers have created a new computer component capable of toggling between 16 possible memory states — the kind of computing versatility provided by brain synapses.

The new component, called a graphene field effect transistor, described Thursday in the journal Nature Communications, could pave the way for advances in brain-inspired computing.

Modern computers are exclusively digital, featuring two states: on-off or zero and one. Engineers at Penn State University are working to build a computer that replicates the brain’s analog nature, capable of hosting many different states.

If a digital computer’s information processing components work like a light switch, toggling only between on and off, then an analog computer is like a light dimmer.

Scientists have been investigating the potential of brain-based computing for decades, but analog computers have been overshadowed by the advances in traditional computing power. However, the rise of big data and smart devices like self-driving cars has highlighted the need for more computing efficiency.

“We have powerful computers, no doubt about that, the problem is you have to store the memory in one place and do the computing somewhere else,” lead researcher Saptarshi Das, an assistant professor of engineering science and mechanics at Penn State, said in a news release.

All the movement of information required by the bifurcation of memory to logic in modern computers puts a strain on speed. It also requires more spaces. Das and his research partners estimate that their graphene field effect transistor can help eliminate this bottleneck.

“We are creating artificial neural networks, which seek to emulate the energy and area efficiencies of the brain,” said study first author Thomas Shranghamer.

“The brain is so compact it can fit on top of your shoulders, whereas a modern supercomputer takes up a space the size of two or three tennis courts,” said Shranghamer, a doctoral student in the Das group.

Brain synapses can be quickly reconfigured to create a variety of neural network patterns. Likewise, the new graphene field effect transistor, formed by a one-atomic-thick layer of carbon atoms, can be used to control 16 possible memory states.

Researchers were able to reconfigure the transistor, effectively toggling between memory states, by applying a brief electric field to the graphene layer.

“What we have shown is that we can control a large number of memory states with precision using simple graphene field effect transistors,” Das said.

Das and his research partners are now looking to work with semiconductor companies to attempt to scale-up the production of the new technology.



Source link

Continue Reading

Science

Mars-sized rogue planet found drifting through the Milky Way

Published

on

Oct. 29 (UPI) — Astronomers have discovered a planetary free agent floating through the Milky Way, unbound to the gravity of any nearby stars. The discovery, detailed Thursday in Astrophysical Journal Letters, suggests the Milky Way may be teeming with rogue planets.

The new exoplanet, the smallest free-floating planet astronomers have found, is too small to be directly observed.

Researchers were able to spot the rogue world — which is somewhere between the size of Mars and Earth — with the assistance of a microlensing event.

“If a massive object — a star or a planet — passes between an Earth-based observer and a distant source star, its gravity may deflect and focus light from the source,” lead study author Przemek Mroz, a postdoctoral scholar at the California Institute of Technology, said in a news release. “The observer will measure a short brightening of the source star.”

“Chances of observing microlensing are extremely slim because three objects — source, lens, and observer — must be nearly perfectly aligned,” Mroz said. “If we observed only one source star, we would have to wait almost a million years to see the source being microlensed.”

To increase their odds of locating microlensing events, researchers rely on surveys. In this instance, astronomers utilized data collected by the OGLE survey, featuring a Chilean telescope and led by a team of astronomers at Warsaw University in Poland.

Every night, the OGLE survey’s 1.3-meter Warsaw Telescope scans the Milky Way center, home to hundreds of millions of stars, looking for changes in stellar brightness.

Thankfully, microlensing detection doesn’t depend on the lensing object’s brightness. It’s the lensing object’s mass that matters. The more massive the lensing object, the longer the microlensing event lasts. The microlensing event caused by the recently discovered rogue planet lasted just a few hours.

Researchers were able to calculate the mass of the rogue planet by measuring the light curve and duration of the microlensing event.

“When we first spotted this event, it was clear that it must have been caused by an extremely tiny object,” said study co-author Radoslaw Poleski, researcher at the Astronomical Observatory of the University of Warsaw.

Researchers were able to determine that the lensing object was likely less massive than Earth and about the same size as Mars. Astronomers were also able to determine that the object was without a host star.

“If the lens were orbiting a star, we would detect its presence in the light curve of the event,” said Poleski. “We can rule out the planet having a star within about 8 astronomical units — the astronomical unit is the distance between the Earth and the sun.”

Since OGLE found the first rogue exoplanet several years ago, the survey has discovered several planetary free agents floating through the Milky Way, but the latest — dubbed OGLE-2016-BLG-1928 — is the smallest rogue planet scientists have found.

“Our discovery demonstrates that low-mass free-floating planets can be detected and characterized using ground-based telescopes,” said Andrzej Udalski, principle investigator on the OGLE project.

Astronomers estimate rogue worlds were initially formed around stars inside protoplanetary disks, but were ejected by gravitational interactions with other young planets. By studying the size distribution of rogue planets, scientists expect to gain a greater understanding of planetary formation and evolution.



Source link

Continue Reading

Trending