Mersal row: BJP’s Raja drags Vijay’s Christian identity to justify GST!

Mangaluru, Apr 23: An astronomical phenomenon, ‘Zero Shadow Day', will be observed in Mangaluru on April 24 and in Udupi on April 25. 

According to a press release from Poornaprajna Amateur Astronomers’ Club, the wonder will commence and people will see their shadows disappear for a few moments at 12:28 pm.

The phenomenon is called as Zero Shadow Day. If a person takes a candle in a dark room and use it to create a shadow of one’s palm on the wall, the hand will cast shadow on the wall as one moves the hand. But when one places the palm on the wall, there will be no shadow.

In the phenomenon, the sun at these times shines exactly above the heads on these days. In astronomy, this point is called as Zenith. The point in the sky directly above an observer at any given location. So it is quite clear now that on Zero Shadow Day, the sun passes through the Zenith as a result of which, all objects will have minimal or no shadow if they are on the ground.

The reason for this happens on some specific days is concerned with astronomy. The earth spins around on its own axis and causes days and nights. It also revolves around the sun causing a year. But the seasons are caused because the axis is tilted at an angle of 23.5 degrees. It is because of this tilt that the sun rises every day in the east gradually moving towards the north till June 21st and then slowly proceeding towards the south till December 21st every year. “We call these days solstice. This means the sun shines between the Tropic of Cancer and Tropic of Capricorn every day passing by the equator on the days we call equinox,” the release stated.

As the earth moves around the sun and revolves on its own axis, for all the people between Tropic of Cancer and Tropic of Capricorn, the Sun at noon moves father and closer to the zenith passing through zenith twice causing two Zero Shadow Days per year. People at Mangaluru will observe this on April 24 and August 18 every year and People in Udupi will observe this on April 25 and August 17 every year.

Places with same latitudes will observe the same days of Zero Shadow but the time would vary with longitude. For example, people of Bengaluru as they share the latitude with Mangaluru will also observe it on April 24. While the people of Mangaluru will observe their shadows disappear at 12.28pm, people of Bengaluru will observe this at 12:17pm. Places like Moodabidri, Bantwal, Sakleshpur and Hassan will also observe Zero Shadow on April 24.

Places like Brahmavar, Karkala, Sringeri, Kudremukha, Chikkamagaluru will observe the Zero Shadow Day on the same day as Udupi on April 25.

London, May 20: The current physical distancing guidelines of 6 feet may be insufficient to prevent COVID-19 transmission, according to a study which says a mild cough in low wind speeds can propel saliva droplets by as much as 18 feet.

Researchers, including those from the University of Nicosia in Cyprus, said a good baseline for studying the airborne transmission of viruses, like the one behind the COVID-19 pandemic, is a deeper understanding of how particles travel through the air when people cough.

In the study, published in the journal Physics of Fluids, they said even with a slight breeze of about four kilometres per hour (kph), saliva travels 18 feet in 5 seconds.

"The droplet cloud will affect both adults and children of different heights," said study co-author Dimitris Drikakis from the University of Nicosia.

According to the scientists, shorter adults and children could be at higher risk if they are located within the trajectory of the saliva droplets.

They said saliva is a complex fluid, which travels suspended in a bulk of surrounding air released by a cough, adding that many factors affect how saliva droplets travel in the air.

These factors, the study noted, include the size and number of droplets, how they interact with one another and the surrounding air as they disperse and evaporate, how heat and mass are transferred, and the humidity and temperature of the surrounding air.

In the study, the scientists created a computer simulation to examine the state of every saliva droplet moving through the air in front of a coughing person.

The model considered the effects of humidity, dispersion force, interactions of molecules of saliva and air, and how the droplets change from liquid to vapour and evaporate, along with a grid representing the space in front of a coughing person.

Each grid, the scientists said, holds information about variables like pressure, fluid velocity, temperature, droplet mass, and droplet position.

The study analysed the fates of nearly 1,008 simulated saliva droplets, and solved as many as 3.7 million equations.

"The purpose of the mathematical modelling and simulation is to take into account all the real coupling or interaction mechanisms that may take place between the main bulk fluid flow and the saliva droplets, and between the saliva droplets themselves," explained Talib Dbouk, another co-author of the study.

However, the researchers added that further studies are needed to determine the effect of ground surface temperature on the behaviour of saliva in air.

They also believe that indoor environments, especially ones with air conditioning, may significantly affect the particle movement through air.

This work is important since it concerns safety distance guidelines, and advances the understanding of the transmission of airborne diseases, Drikakis said.

London/Milan, Jun 2: World Health Organization experts and a range of other scientists said on Monday there was no evidence to support an assertion by a high profile Italian doctor that the coronavirus causing the COVID-19 pandemic has been losing potency.

Professor Alberto Zangrillo, head of intensive care at Italy's San Raffaele Hospital in Lombardy, which bore the brunt of Italy's COVID-19 epidemic, on Sunday told state television that the new coronavirus "clinically no longer exists".

But WHO epidemiologist Maria Van Kerkhove, as well as several other experts on viruses and infectious diseases, said Zangrillo's comments were not supported by scientific evidence.

There is no data to show the new coronavirus is changing significantly, either in its form of transmission or in the severity of the disease it causes, they said.

"In terms of transmissibility, that has not changed, in terms of severity, that has not changed," Van Kerkhove told reporters.

It is not unusual for viruses to mutate and adapt as they spread, and the debate on Monday highlights how scientists are monitoring and tracking the new virus. The COVID-19 pandemic has so far killed more than 370,000 people and infected more than 6 million.

Martin Hibberd, a professor of emerging infectious disease at the London School of Hygiene & Tropical Medicine, said major studies looking at genetic changes in the SARS-CoV-2 virus that causes COVID-19 did not support the idea that it was becoming less potent, or weakening in any way.

"With data from more than 35,000 whole virus genomes, there is currently no evidence that there is any significant difference relating to severity," he said in an emailed comment.

Zangrillo, well known in Italy as the personal doctor of former Prime Minister Silvio Berlusconi, said his comments were backed up by a study conducted by a fellow scientist, Massimo Clementi, which Zangrillo said would be published next week.

Zangrillo told Reuters: "We have never said that the virus has changed, we said that the interaction between the virus and the host has definitely changed."

He said this could be due either to different characteristics of the virus, which he said they had not yet identified, or different characteristics in those infected.

The study by Clementi, who is director of the microbiology and virology laboratory of San Raffaele, compared virus samples from COVID-19 patients at the Milan-based hospital in March with samples from patients with the disease in May.

"The result was unambiguous: an extremely significant difference between the viral load of patients admitted in March compared to" those admitted last month, Zangrillo said.

Oscar MacLean, an expert at the University of Glasgow's Centre for Virus Research, said suggestions that the virus was weakening were "not supported by anything in the scientific literature and also seem fairly implausible on genetic grounds."