3D images show what lies beneath Mars poles

January 4, 2017

Washington, Jan 4: Scientists using data from a NASA probe have unveiled 3D subsurface images of Mars polar ice caps, showing previously obscured layering, larger volume of frozen carbon dioxide and bowl-shaped features that may be buried impact craters.mars

The information will help scientists better understand Martian climate changes and may allow them to determine the age of the polar caps without using climate models.

The 3D data volumes were assembled from observations by the Shallow Radar (SHARAD) onboard NASA's Mars Reconnaissance Orbiter (MRO) during more than 2000 orbit passes over each Martian pole.

"We have applied industry-developed techniques in a very novel fashion to a martian dataset, producing 3D volumes that are each over 600 times larger than any terrestrial or planetary dataset of this kind," said Nathaniel E Putzig, a senior scientist at the Planetary Science Institute in the US.

"It is gratifying to see so plainly in the SHARAD volumes structures that took years of effort to characterise with the single-orbit profiles," Putzig said.

Layering seen at the surface of the martian polar caps has been studied for decades. It has long been thought to represent a record of climate changes on that planet.

The interior structures of the caps remained a mystery until the arrival of radar sounders at Mars in the last decade.

An early version of the north polar 3D volume helped to assess the quantity of water ice transferred to the polar caps in the most recent retreat from a martian ice age.

First looks at the south polar 3D volume indicate that previously mapped deposits of carbon dioxide ice are somewhat larger than reported.

In both polar 3D volumes, known impact craters in and near the polar caps that are partially filled with ice have distinctive bowl-shaped signatures in the radar data, and similar signatures are found elsewhere within the polar ices but without any surface expression.

Whether the latter structures truly are impact craters remains to be determined.
Age estimates of planetary surfaces throughout the solar system rely on statistical data for impact craters on the Moon's surface calibrated to radiometrically dated samples returned during the Apollo programme.

This method has been used to estimate the surface ages of the martian polar caps, but estimates for the ages of the caps themselves have had to rely on numerical models of past climate changes.

If a sufficient number of the bowl-shaped features found in the radar volumes are shown to be impact craters, scientists will be able to assess the age of the polar caps using cratering statistics alone.

The extent to which age estimates from this new volumetric method agree or disagree with those from climate models will have important implications for the accuracy of these dating techniques.

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Agencies
July 19,2020

New Delhi, Jul 19: Indian equities will be driven by a host of factors like corporate earnings, coronavirus cases trend and geo-political developments this week, according to analysts.

Market participants will also keenly watch the progress of monsoon, with experts saying that the farm sector revival will play a key role in lifting the coronavirus-hit economy.

"With no major event, the ongoing earnings season and global cues will continue to dictate the market trend. Besides, the progress of monsoon will also be closely watched," Ajit Mishra, VP - Research, Religare Broking, said.

Globally, the rising coronavirus infections and geo-political tensions have created uncertainty on the economic recovery front.

With India's COVID-19 cases fast approaching the 11 lakh mark, the third-highest behind the US and Brazil, and the death toll nearing 27,000, participants are expected to tread cautiously going forward.

At global level, confirmed COVID-19 cases have crossed 1.4 crore and deaths totalled about 6 lakh.

Markets globally will closely follow developments on the trade and political level between the US and China, according to analysts.

"We would continue witnessing stock-specific action as the earnings season unfold. Though the near-term momentum looks positive, we would advise traders to be cautious, given flaring US-China trade relations, persistent rise in virus cases and implementation of fresh lockdowns in parts of the country," said Siddhartha Khemka, Head - Retail Research, Motilal Oswal Financial Services Ltd.

HDFC Bank will remain in focus on Monday after having announced its June quarter earnings on Saturday.

The lender reported 19.6 per cent rise in its standalone net profit at Rs 6,658.62 crore for April-June 2020; while its income rose to Rs 34,453.28 crore during the quarter.

Other major companies to announce their quarterly results this week are Axis Bank, Bajaj Finance, Hindustan Unilever Limited, Bajaj Auto and ITC.

"Going ahead market participants will closely track the development related to covid vaccine, the rising infection of coronavirus, development on economic activities, corporate earnings and US-China relationship," said Sumeet Bagadia, Executive Director, Choice Broking.

On weekly basis, the Sensex gathered 425.81 points or 1.16 per cent, and the Nifty gained 133.65 points or 1.24 per cent.

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Agencies
June 19,2020

Denser places, assumed by many to be more conducive to the spread of the coronavirus that causes COVID-19, are not linked to higher infection rates, say researchers.

The study, led by Johns Hopkins University, published in the Journal of the American Planning Association, also found that dense areas were associated with lower COVID-19 death rates.

"These findings suggest that urban planners should continue to practice and advocate for compact places rather than sprawling ones, due to the myriad well-established benefits of the former, including health benefits," says study lead author Shima Hamidi from Johns Hopkins Bloomberg School of Public Health in the US.

For their analysis, the researchers examined SARS-CoV-2 infection rates and COVID-19 death rates in 913 metropolitan counties in the US.

When other factors such as race and education were taken into account, the authors found that county density was not significantly associated with county infection rate.

The findings also showed that denser counties, as compared to more sprawling ones, tended to have lower death rates--possibly because they enjoyed a higher level of development including better health care systems.

On the other hand, the research found that higher coronavirus infection and COVID-19 mortality rates in counties are more related to the larger context of metropolitan size in which counties are located.

Large metropolitan areas with a higher number of counties tightly linked together through economic, social, and commuting relationships are the most vulnerable to the pandemic outbreaks.

According to the researchers, recent polls suggest that many US citizens now consider an exodus from big cities likely, possibly due to the belief that more density equals more infection risk.

Some government officials have posited that urban density is linked to the transmissibility of the virus.

"The fact that density is unrelated to confirmed virus infection rates and inversely related to confirmed COVID-19 death rates is important, unexpected, and profound," said Hamidi.

"It counters a narrative that, absent data and analysis, would challenge the foundation of modern cities and could lead to a population shift from urban centres to suburban and exurban areas," Hamidi added.

The analysis found that after controlling for factors such as metropolitan size, education, race, and age, doubling the activity density was associated with an 11.3 per cent lower death rate.

The authors said that this is possibly due to faster and more widespread adoption of social distancing practices and better quality of health care in areas of denser population.

The researchers concluded that a higher county population, a higher proportion of people age 60 and up, a lower proportion of college-educated people, and a higher proportion of African Americans were all associated with a greater infection rate and mortality rate.

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News Network
July 28,2020

Bengaluru, Jul 28: Congress leader Siddaramaiah on Monday alleged that BJP is trying to destabilise the Congress government in Rajasthan.

"It is the duty of the Governor to act according to the decision of the state cabinet. But he is acting like a central government puppet," he said at a protest organised here by Karnataka Pradesh Congress Committee (KPCC).

He said the Congress is protesting across the country to save democracy and save the constitution.

"We are not fighting through violence. We are protesting peacefully. The Constitution has given the right to protest in a democratic system," he said.

He accused the BJP of "being disrespectful" to the Constitution.

"Governments must walk within the framework of the Constitution. The Constitution gives everyone rights and duties. BJP destabilises elected governments and buys our legislators by horse-trading by spending crores of money. The same thing happened in Karnataka as well," he alleged.

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