New laser technology can make objects invisible

Agencies
September 14, 2017

London, Sept 14: Scientists have developed a cloaking technology that can make opaque materials invisible by using light waves from lasers, paving the way for novel ways of camouflaging objects.

A completely opaque material is irradiated from above with a specific wave pattern - with the effect that light waves from the left can pass through the material without any obstruction.

The technique can be applied to different kinds of waves, and should work with sound waves just as well as with light waves, researchers said.

"Complex materials such as a sugar cube are opaque, because light waves inside them are scattered multiple times," said Stefan Rotter, from Technische Universitat Wien (TU Wien) in Austria.

"A light wave can enter and exit the object, but will never pass through the medium on a straight line. Instead, it is scattered into all possible directions," said Rotter.

For years many different attempts have been made to outwit this kind of scattering, creating a "cloak of invisibility."

Special materials have been worked out, for example, which are able to guide light waves around an object. Alternatively, also experiments have been performed with objects that can emit light by themselves.

When an electronic display sends out exactly the same light as it absorbs in the back, it can appear invisible, at least when looked at in the right angle.

"We did not want to reroute the light waves, nor did we want to restore them with additional displays. Our goal was to guide the original light wave through the object, as if the object was not there at all," said Andre Brandstotter, one of the authors of the study.

"This sounds strange, but with certain materials and using our special wave technology, it is indeed possible," said Brandstotter.

To make the laser shine, energy has to be supplied by means of a pump beam. Otherwise, the laser material behaves just like any other material - it absorbs part of the incident light.

"The crucial point is to pump energy into the material in a spatially tailored way such that light is amplified in exactly the right places, while allowing for absorption at other parts of the material," said Konstantinos Makris from the University of Crete in Greece.

"To achieve this, a beam with exactly the right pattern has to be projected onto the material from above - like from a standard video projector, except with much higher resolution," said Makris.

If this pattern perfectly corresponds to the inner irregularities of the material which usually scatter the light, then the projection from above can effectively switch off the scattering, and another beam of light travelling through the material from one side can pass without any obstruction, scattering or loss.

"Mathematically, it is not immediately obvious that it is at all possible to find such a pattern," said Rotter.

"Every object we want to make transparent has to be irradiated with its own specific pattern - depending on the microscopic details of the scattering process inside," he said.

"The method we developed now allows us to calculate the right pattern for any arbitrary scattering medium," he added.

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Agencies
July 15,2020

New Delhi, Jul 15: The employees union of state-run telecom operator BSNL will stage protests across the country on Thursday on a host of issues including the cancellation of its 4G tender and non-payment of salaries.

All major unions are organising ‘lunch-hour black-flag' demonstrations throughout the country under the banner of All Unions and Association of BSNL (AUAB), said a statement by AUAB. These demonstrations will be organised, by maintaining social distancing and by taking other precautions, like wearing of masks. The BSNL employees will also wear black-badges the whole day on July 16.

The employees body would demand that BSNL should immediately be allowed to roll out its 4G services and the tender should be issued immediately. Further, they want that in the matter of procuring new equipment and upgradation, there should not be any discrimination between BSNL and other private telecom service providers.

Recently, the Centre cancelled the 4G upgradation tender for BSNL as it had decided to come up with fresh specifications for the upgrade process, in a move to keep Chinese technology companies at bay as the border tussle escalated with the northern neighbour.

The Department of Telecommunications (DoT) would issue a fresh tender for the same, and people in the know said that Chinese companies may not be allowed to participate.

"The agitational programme is being organised to express the deep anguish and resentment of the employees against cancellation of BSNL's 4G tender, cancellation of BSNL's proposal for upgradation of its 49,300 BTSs to 4G, abnormal delay in issuing ‘Add on Order' for 4G equipments, inordinate delay in the implementation of BSNL's Revival Package and against the non-settlement of the burning problems of the employees," said the statement.

The umbrella body of BSNL's employees' unions noted that rolling out of 4G services is the backbone for the revival of this telecom PSU, but the recent cancellation of the tender floated by BSNL for procuring 4G equipment at a cost of Rs 9,300 crore, has brought the company back to square one.

It said that BSNL is already having 49,300 base transceiver stations (BTS), which are 4G compatible and through minor upgradation, all these equipment can be converted into 4G BTSs with an investment of about Rs 1,500 crore.

In addition to this, BSNL could have added another 15,000 BTSs, by placing an Add on Order to the existing mobile tender, it added.

Noting that in October 2019, the PSU could have rolled out pan-India 4G services, AUAB said: "Being the sole owner of the company, the Government of India also cannot shirk its responsibility in this matter."

"Adding insult to injury, the tender floated by BSNL to procure 4G equipment, has been cancelled by the government, based on a complaint from the Telecom Equipments and Services Promotional Council (TEPC)," it said.

AUAB said that BSNL is already lagging four years behind the private operators, in terms of 4G and the cancellation of the tender is going to inordinately delay the company's 4G launch.

Saying that TEPC's contention has been to bar foreign companies from participating in BSNL's tender, AUAB statement pointed out that when private operators are procuring equipment from multinationals, "why BSNL alone should be compelled to procure 4G equipments from domestic vendors, whose 4G technology is not tested or proven so far."

It alleged a conspiracy to destabilise BSNL by disrupting its rolling out of 4G services.

AUAB further said that even after the lapse of nine months, the implementation of the much publicised BSNL's Revival Package is moving at a snail's pace.

"Except the swift retrenchment of 79,000 BSNL employees under VRS, all other assurances given in BSNL's Revival Package have been put in cold storage."

The management should ensure that the salary payment of the employees is made on the last working day of every month. Deductions made from employees' salary, on account of "society dues", should immediately be remitted, it said.

Regarding the monetisation of the company's assets under the revival package, the organisation said that the land asset should not be handed over to corporates, at "throwaway" prices.

"These lands should be sold in a transparent manner and at the prevailing market rates. They should not be sold at book value or at circle rates. The AUAB will strictly monitor these dealings," it said.

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News Network
May 7,2020

Toronto, May 7: Scientists have uncovered how bats can carry the MERS coronavirus without getting sick, shedding light on what triggers coronaviruses, including the one behind the COVID-19 pandemic, to jump to humans.

According to the study, published in the journal Scientific Reports, coronaviruses like the Middle East respiratory syndrome (MERS) virus, and the COVID19-causing SARS-CoV-2 virus, are thought to have originated in bats.

While these viruses can cause serious, and often fatal disease in people, bats seem unharmed, the researchers, including those from the University of Saskatchewan (USask) in Canada, said.

"The bats don't get rid of the virus and yet don't get sick. We wanted to understand why the MERS virus doesn't shut down the bat immune responses as it does in humans," said USask microbiologist Vikram Misra.

In the study, the scientists demonstrated that cells from an insect-eating brown bat can be persistently infected with MERS coronavirus for months, due to important adaptations from both the bat and the virus working together.

"Instead of killing bat cells as the virus does with human cells, the MERS coronavirus enters a long-term relationship with the host, maintained by the bat's unique 'super' immune system," said Misra, one of the study's co-authors.

"SARS-CoV-2 is thought to operate in the same way," he added.

Stresses on bats, such as wet markets, other diseases, and habitat loss, may have a role in coronavirus spilling over to other species, the study noted.

"When a bat experiences stress to their immune system, it disrupts this immune system-virus balance and allows the virus to multiply," Misra said.

The scientists, involved in the study, had earlier developed a potential treatment for MERS-CoV, and are currently working towards a vaccine against COVID-19.

While camels are the known intermediate hosts of MERS-CoV, they said bats are suspected to be the ancestral host.

There is no vaccine for either SARS-CoV-2 or MERS, the researchers noted.

Follow latest updates on the COVID-19 pandemic here

"We see that the MERS coronavirus can very quickly adapt itself to a particular niche, and although we do not completely understand what is going on, this demonstrates how coronaviruses are able to jump from species to species so effortlessly," said USask scientist Darryl Falzarano, who co-led the study.

According to Misra, coronaviruses rapidly adapt to the species they infect, but little is known on the molecular interactions of these viruses with their natural bat hosts.

An earlier study had shown that bat coronaviruses can persist in their natural bat host for at least four months of hibernation.

When exposed to the MERS virus, the researchers said, bat cells adapt, not by producing inflammation-causing proteins that are hallmarks of getting sick, but instead by maintaining a natural antiviral response.

On the contrary, they said this function shuts down in other species, including humans.

The MERS virus, the researchers said, also adapts to the bat host cells by very rapidly mutating one specific gene.

These adaptations, according to the study, result in the virus remaining long-term in the bat, but being rendered harmless until something like a disease, or other stressors, upsets this balance.

In future experiments, the scientists hope to understand how the bat-borne MERS virus adapts to infection and replication in human cells.

"This information may be critical for predicting the next bat virus that will cause a pandemic," Misra said.

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Agencies
June 12,2020

New Delhi, Jun 12: The Supreme Court on Friday asked Solicitor General Tushar Mehta to convene a meeting of the Finance Ministry and RBI officials over the weekend to decide whether interest incurred on EMIs during the moratorium period can be charged by banks.

A bench comprising Justices Ashok Bhushan, Sanjay Kishan Kaul and M.R. Shah queried Mehta as the court was concerned since the Centre has deferred loan for three months.

"Then how can interest of these 3 months be added?" the apex bench asked. Mehta replied: "I need to sit down with the RBI officials and have a meeting."

SBI's counsel, senior advocate Mukul Rohatgi, intervened during the proceedings and said "all banks are of the view that interest cannot be waived for a six month EMI moratorium period".

"We need to discuss it with the RBI," insisted Rohatgi.

Justice Bhushan then asked Mehta to convene a meeting of the RBI and Finance Ministry officials over the weekend, and listed the matter for further hearing on June 17.

The top court, during the hearing, indicated that it was not considering a complete waiver of interest but was only concerned that postponement of interest shouldn't accrue further interest on it.

After the RBI said the waiver of interest charges on EMIs during moratorium will lead to loss of 1 per cent of the nation's GDP, the top court had earlier asked the Finance Ministry to reply, whether the interest could be waived or it would continue during the moratorium period.

The top court said these are not normal times, and it is a serious issue, as on one hand moratorium is granted and then, the interest is charged on loans during this period.

"There are two issues in this (matter). No interest during the moratorium period and no interest on interest," said Justice Bhushan. The observation from the bench came on a petition by Gajendra Sharma, in which he sought a direction to declare portion of the RBI's March 27 notification as ultra vires to the extent it charged interest on the loan amount during the moratorium period.

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