'New light-absorbent material to cool buildings, cars'

February 5, 2017

Los Angeles, Feb 5: Scientists have developed a thin, flexible, lightweight material that can block thermal detection and absorb light from every angle to keep buildings and cars cool on hot summer days.

absorbentThe material, developed by engineers at the University of California San Diego in the US, is called a near-perfect broadband absorber.

It absorbs more than 87 per cent of near-infrared light (1,200 to 2,200 nanometre wavelengths), with 98 per cent absorption at 1,550 nanometres, the wavelength for fiber optic communication.

The material is capable of absorbing light from every angle. It also can theoretically be customised to absorb certain wavelengths of light while letting others pass through.

Materials that "perfectly" absorb light already exist, but they are bulky and can break when bent. They also cannot be controlled to absorb only a selected range of wavelengths, which is a disadvantage for certain applications.

Imagine if a window coating used for cooling not only blocked infrared radiation, but also normal light and radio waves that transmit television and radio programmes.

By developing a novel nanoparticle-based design, a team led by professors Zhaowei Liu and Donald Sirbuly at the UC San Diego has created a broadband absorber that is thin, flexible and tunable.

"This material offers broadband, yet selective absorption that could be tuned to distinct parts of the electromagnetic spectrum," said Liu.

The absorber relies on optical phenomena known as surface plasmon resonances, which are collective movements of free electrons that occur on the surface of metal nanoparticles upon interaction with certain wavelengths of light.

Metal nanoparticles can carry a lot of free electrons, so they exhibit strong surface plasmon resonance - but mainly in visible light, not in the infrared.

The researchers reasoned that if they could change the number of free electron carriers, they could tune the material's surface plasmon resonance to different wavelengths of light.

"Make this number lower, and we can push the plasmon resonance to the infrared. Make the number higher, with more electrons, and we can push the plasmon resonance to the ultraviolet region," said Sirbuly.

The problem with this approach is that it is difficult to do in metals. To address this challenge, engineers designed and built an absorber from materials that could be modified, or doped, to carry a different amount of free electrons: semiconductors.

Researchers used a semiconductor called zinc oxide, which has a moderate number of free electrons, and combined it with its metallic version, aluminium-doped zinc oxide, which houses a high number of free electrons — not as much as an actual metal, but enough to give it plasmonic properties in the infrared.

The study was published in the journal Proceedings of the National Academy of Sciences.

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Agencies
July 11,2020

Citing the current dismal aviation scenario, Air India is terminating the services of trainee cabin crew and cabin crew by withdrawing the offer of employment of those who were under training.

As per sources, the new crew and trainee pilots might reduce contracts from five years to one year. Sources said Air India is terminating 1,200 crew and employees who are more than 55-yr-old including 190 trainee pilots.

In a letter reviewed by IANS, Air India has informed an applicant who had been selected as cabin crew in August 2019 subject to successful completion of training.

"On behalf of Air India we would like to thank you for the interest shown by you in joining our organization. However, in view of the current aviation scenario, it would not be possible for Air India to impart any further training to you for engaging your services," the company said.

"In view of the above reasons, which are beyond the control of the company, it has been decided to discontinue your training arrangements and dispense with the offer of engagement with immediate effect. The bank guarantee furnished by you at the time of joining is returned herewith," Air India told the cabin crew.

"Once again on behalf of Air India we thank you for your cooperation and trust that you will appreciate the circumstances under which we are constrained to discontinue the training arrangements," the carrier said.

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Agencies
January 7,2020

Washington, Jan 7: Facebook will ban deepfake videos ahead of the US elections but the new policy will still allow heavily edited clips so long as they are parody or satire, the social media giant said Tuesday.

Deepfake videos are hyper-realistic doctored clips made using artificial intelligence or programs that have been designed to accurately fake real human movements.

In a blog published following a Washington Post report, Facebook said it would begin removing clips that were edited--beyond for clarity and quality--in ways that "aren't apparent to an average person" and could mislead people.

Clips would be removed if they were "the product of artificial intelligence or machine learning that merges, replaces or superimposes content onto a video, making it appear to be authentic," the statement from Facebook vice-president Monika Bickert said.

However, the statement added: "This policy does not extend to content that is parody or satire, or video that has been edited solely to omit or change the order of words."

US media noted the new guidelines would not cover videos such as the 2019 viral clip -- which was not a deepfake -- of House Speaker Nancy Pelosi that appeared to show her slurring her words.

Facebook also gave no indication on the number of people assigned to identify and take down the offending videos, but said videos failing to meet its usual guidelines would be removed, and those flagged clips would be reviewed by teams of third-party fact-checkers -- among them AFP.

The news agency has been paid by the social media giant to fact-check posts across 30 countries and 10 languages as part of a program starting in December 2016, and including more than 60 organisations.

Content labeled "false" is not always removed from newsfeeds but is downgraded so fewer people see it -- alongside a warning explaining why the post is misleading.

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Agencies
January 10,2020

Indian enterprises were flooded with a whopping 14.6 crore malware threats in 2019 - a growth of 48 per cent (year-on-year) compared to 2018, a new report said on Friday.

Manufacturing, BFSI (banking, financial services and insurance), education, healthcare, IT/ITES, and the government were the most at-risk industries in the country, said the report from Seqrite, the enterprise arm of Pune-based IT security firm Quick Heal Technologies.

Interestingly, almost a quarter (23 per cent) of the threats were identified through 'Signatureless behaviour-based' detection by Seqrite, indicating how a growing number of cybercriminals were deploying new or previously unknown threat vectors to compromise enterprise security.

"With the latest Seqrite annual threat report, we want to empower CIOs, CISOs, business leaders and all key public stakeholders with the insights they need to combat the growing complexity of the threat landscape," said Sanjay Katkar, Joint Managing Director and CTO, Quick Heal Technologies.

The most prominent trend was the drastic increase in the volume, intensity, and sophistication of cyber-attack campaigns targeting Indian enterprises in 2019.

The rapid integration of IoT devices, BYOD (bring your own device), and third-party APIs into enterprise networks has created newer security vulnerabilities that might go unnoticed until a major breach occurs.

Threat researchers at Seqrite observed several large-scale advanced persistent threats (APT) attacks deployed against organisations in the government sector.

"The entry of nation-states and organised cybercrime cells into the fray is expected to add more complication to this situation and will require Indian government bodies and corporate enterprises to shore up their cyber defence strategies in 2020 and beyond," the report noted.

More alarming, however, was the continued lack of security awareness amongst enterprises and government organisations.

"Unsecured Remote Desktop Protocol (RDP) and Server Message Block (SMB) protocols continued to be targeted through brute-force attacks," said the report.

Spear phishing attack campaigns leveraging Office exploits and infected macros were also used extensively by cybercriminals to gain access to enterprise networks and steal critical data.

"India's digital journey depends on ensuring robust cybersecurity for all stakeholders within the enterprise ecosystem," said Katkar.

The sharp spike should be a cause of concern for CIOs and CISOs in the country, especially given the growing digital penetration within their enterprise networks.

"With network vulnerabilities and potential entry points increasing at a rapid pace, threat actors are expected to leverage artificial intelligence (AI) capabilities to power their malware campaigns in the future to capitalise on newer attack vectors," the report added.

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