Antarctica’s retreating ice may reshape Earth
In the worst case scenario, Antarctica’s melt could push sea levels up 10 feet worldwide in a century or two.
From the ground in this extreme northern part of Antarctica, spectacularly white and blinding ice seems to extend forever. What can’t be seen is the battle raging underfoot to reshape Earth.
Water is eating away at the Antarctic ice, melting it where it hits the oceans. As the ice sheets slowly thaw, water pours into the sea 118 billion metric tonnes per year for the past decade, according to NASA satellite calculations. That’s the weight of more than 356,000 Empire State Buildings, enough ice melt to fill more than 1.3 million Olympic swimming pools. And the melting is accelerating.
In the worst case scenario, Antarctica’s melt could push sea levels up 10 feet worldwide in a century or two, recurving heavily populated coastlines.
‘Ground zero of climate change’
“Parts of Antarctica are melting so rapidly it has become “ground zero of global climate change without a doubt,” said Harvard geophysicist Jerry Mitrovica.
As chinstrap penguins waddled behind him, Peter Convey of the British Antarctic Survey reflected on changes he could see on Robert Island, a small-scale example and perhaps early warning signal of what’s happening to the peninsula and rest of the continent as a whole.
“I was last here 10 years ago,” Mr. Convey said during a rare sunny day on the island, with temperatures just above freezing. “And if you compare what I saw back then to now, the basic difference due to warming is that the permanent patches of snow and ice are smaller. They’re still there behind me, but they’re smaller than they were.”
Robert Island hits all the senses — the stomach-turning smell of penguins; soft moss that invites the rare visitor to lie down, as if on a water bed; brown mud, akin to stepping in gooey chocolate. Patches of the moss, which alternates from fluorescent green to rust red, have grown large enough to be football fields. Though 97 per cent of the Antarctic Peninsula is still covered with ice, entire valleys are now free of it, ice is thinner elsewhere and glaciers have retreated, Mr. Convey said.
Dressed in a big red parka and sky blue hat, plant biologist Angelica Casanova has to take her gloves off to collect samples, leaving her hands bluish purple from the cold. Ms. Casanova says she can’t help but notice the changes since she began coming to the island in 1995. Increasingly, plants are taking root in the earth and stone deposited by retreating glaciers, she says.
“It’s interesting because the vegetation in some way responds positively. It grows more,” she said, a few steps from a sleeping Weddell seal. “What is regrettable is that all the scientific information that we’re seeing says there’s been a lot of glacier retreat and that worries us.”
Just last month, scientists noticed in satellite images that a giant crack in an ice shelf on the peninsula called Larsen C had grown by about 20 km in 2014. Ominously, the split broke through a type of ice band that usually stops such cracks. If it keeps going, it could cause the breaking off of a giant iceberg somewhere between the size of Rhode Island and Delaware, about 4,600 to 6,400 sq. km, said British Antarctic Survey scientist Paul Holland. And there’s a small chance it could cause the entire Scotland-sized Larsen C ice shelf to collapse like its sister shelf, Larsen B, did in a dramatic way in 2002.
No longer in balance
A few years back, scientists figured Antarctica as a whole was in balance, neither gaining nor losing ice. Experts worried more about Greenland; it was easier to get to and more noticeable, but once they got a better look at the bottom of the world, the focus of their fears shifted. Now scientists in two different studies use the words “irreversible” and “unstoppable” to talk about the melting in West Antarctica. Ice is gaining in East Antarctica, where the air and water are cooler, but not nearly as much as it is melting to the west.
“Before Antarctica was much of a wild card,” said University of Washington ice scientist Ian Joughin. “Now I would say it’s less of a wild card and scarier than we thought before.”
Over at NASA, ice scientist Eric Rignot said the melting “is going way faster than anyone had thought. It’s kind of a red flag”.
What’s happening is simple physics. Warm water eats away at the ice from underneath. Then more ice is exposed to the water, and it too melts. Finally, the ice above the water collapses into the water and melts.
Climate change has shifted the wind pattern around the continent, pushing warmer water farther north against and below the western ice sheet and the peninsula. The warm, more northerly water replaces the cooler water that had been there. It’s only a couple of degrees Fahrenheit warmer than the water that used to be there, but that makes a huge difference in melting, scientists said.
The world’s fate hangs on the question of how fast the ice melts.
At its current rate, the rise of the world’s oceans from Antarctica’s ice melt would be barely noticeable, about one-third of a millimetre a year. The oceans are that vast.
But if all the West Antarctic ice sheet that’s connected to water melts unstoppably, as several experts predict, there will not be time to prepare. Scientists estimate it will take anywhere from 200 to 1,000 years to melt enough ice to raise seas by 10 feet, maybe only 100 years in a worst case scenario. If that plays out, developed coastal cities such as New York and Guangzhou could face up to $1 trillion a year in flood damage within a few decades and countless other population centres will be vulnerable.
“Changing the climate of the Earth or thinning glaciers is fine as long as you don’t do it too fast. And right now we are doing it as fast as we can. It’s not good,” said Mr. Rignot, of NASA. “We have to stop it; or we have to slow it down as best as we can.”
Indian monsoon fluctuated during ice age: study
As ice ages on Earth waxed and waned over time spans of thousands of years, there were substantial fluctuations in monsoon intensity over India. But while the rains in north-eastern India declined during the last ice age, the monsoon in East Asia remained remarkably robust, a new study has found.
During an ice age, vast sheets of ice and glaciers cover much of the planet. The last ice age occurred 75,000 to 20,000 years ago.
A team of Chinese scientists, along with colleagues in the U.S., used levels of isotopes of thorium and oxygen found in stalagmites in a cave in south-western China to reconstruct how the monsoon over north-eastern India, the Himalayan foothills, Bangladesh and northern Indochina fluctuated over the past 2,52,000 years. Their research has just been published in the Proceedings of the National Academy of Sciences (PNAS).
The paper reconfirms earlier work showing that the Indian monsoon weakened during the ice ages, observed J. Srinivasan of the Centre for Atmospheric and Oceanic Sciences at the Indian Institute of Science, Bangalore. In their paper, Yanjun Cai and the other scientists also drew on previously collected isotopic data from caves in eastern China as well as computer simulations.
How aerosols affect tropical rainfall
The inter-tropical convergence zone (ITCZ), a belt of precipitation caused by the trade winds (which blow from east to west in the north and southern hemispheres near the equator) has been shifting southwards in Central America since 1900, when the industrial revolution and associated atmospheric pollution began in real earnest.
The reason for this shift according to a new study is the cooling effect of aerosols which, produced in large quantities due to industrialisation reflect sun’s heat back into space and work in contrast to green house gases which trap atmospheric heat and cause global warming.
Cooling of the atmosphere results in less rainfall and dry conditions while warming leads to evaporation, convection and rainfall. The study found that since 1900 there has been a steady increase in rainfall in the southern tropics, in contrast to a steady decrease in the northern tropics and the ITCZ has shifted southwards in the Central American region.
The study was conducted by lead- author Dr. Harriet E. Ridley, Department of Earth Sciences, University of Durham, Durham, UK and others. The researchers analysed a stalagmite found in a cave in Belize (a Central American nation) to construct a record of rainfall patterns in the region over the past 450 years. This site is near the northernmost extent of the ITCZ, a remarkably sensitive location for reconstructing even minor variations in ITCZ position.The work was published recently in the journal Nature Geoscience.
The team measured Carbon -13 (δ13C) isotope levels over this period in the various layers of the stalagmite. Carbon isotope serves as a good proxy for rainfall as recorded in the stalagmite over the thousands of years of its formation. The authors support this view using instrumental data from the region.
Stalagmites grow incrementally as drops of water seep through the overlying rock. The growth of the stalagmite is therefore linked to the amount of water reaching it, which is in part controlled by rainfall. Furthermore, every drop of water reaching the cave has a unique chemical signature which is controlled by the prevailing climate, most often temperature and rainfall amount. This chemical signature is then incorporated into the stalagmite layers as it grows. By ‘chemical signature’ in this case, is meant oxygen and carbon isotopes. At the Belize cave site the carbon isotope value of each layer of the stalagmite is controlled by the amount of water dripping onto the stalagmite and therefore the amount of rainfall. As this carbon isotope values change through time one can see how rainfall has changed.
The stalagmite portions were dated by measuring Uranium-Thorium ratios over the past centuries.
U-Th dating is based on the radioactive decay of uranium-234 to thorium-230. This decay is part of a much longer decay series. In order to conduct Uranium-Thorium dating, powder samples (19 in this case) spread between the top and bottom of the stalagmite were taken.
”A key factor in the method is that uranium is soluble in water while the daughter products are non-soluble. This means that uranium is present in water which seeps into limestone caves and is incorporated into stalagmites but it’s non-soluble daughter products are not. Daughter isotopes present in the sample increase through time as the uranium decays and the ratio of the uranium to the thorium is measured to provide an age estimate,” clarified Dr. Ridley in an email to this correspondent.
The study revealed that rainfall in the Northern Tropics where Belize is situated indeed declined dramatically since 1900 when the industrial revolution began.
The authors point to increased aerosol concentrations in the Northern Tropics of Central America as the likely cause. There have been drying events even before 1900, but these coincided with Northern Hemisphere volcanic eruptions which sent aerosols into the atmosphere causing cooling and therefore, dry conditions. Similarly, volcanic eruptions in the southern hemisphere resulted in temporary cooling in the southern tropics.
Bacterium jumps host with a single mutation
With just a single mutation, a disease-causing bacterium was able to switch hosts. But it was a human pathogen that made the leap and gained the ability to infect animals, not the other way round.
The ST121 strain of Staphylococcus aureus is not one to be trifled with, capable of producing life-threatening disease in people. After a highly virulent ST121 strain spread through commercial rabbit farms in developed countries, a group of European researchers decided to investigate how such a strain had emerged.
Bacteria are notorious for their ability to exchange bits of their DNA, even across species. Such ‘mobile genetic elements’ can give microbes the ability to thrive in new hosts, make them resistant to antibiotics and be able to secrete potent toxins.
Indeed, transfer of mobile genetic elements was implicated in previous jumps of S. aureus strains from humans to livestock. But that was not the case with the ST121 strain in rabbits, say José R Penadés of the University of Glasgow in the U.K. and his colleagues in a paper published online by Nature Genetics last week.
They analysed the full genome sequences of 23 different ST121 strains from humans and rabbits obtained from eight countries in three continents covering a period of 50 years. The most likely explanation for the emergence of the ST121 strain associated with epidemics at rabbit farms was “a single human-to-rabbit host jump that occurred more than 38 years ago,” their paper noted.
The scientists then looked for mutations that all the rabbit ST121 strains shared but which the human strains lacked. A dozen genes in the rabbit strains had been affected by such mutations.
In order to identify which mutations allowed a human ST121 to infect rabbits, they reversed those mutations in two representative rabbit strains and checked whether the resulting bacteria could still produce skin sores in the animals. They also introduced the mutations into a human ST121 strain and tested that bacterium too in a similar fashion.
Mutations in 10 genes had no effect on bacterial infectivity or the severity of infection in rabbits.
However, with one particular mutation in the dltB gene, a human ST121 strain became capable of infecting rabbits, giving rise to sores similar to those produced by a rabbit strain. Two more mutations in the same gene increased the bacterium’s infectivity.
It was “amazing” and “completely unexpected” that a single mutation could make a human S. aureus strain capable of infecting rabbits, remarked Prof. Penadés in an email.
Further analysis showed that similar human-to-rabbit jumps of other S. aureus strains had probably occurred on numerous occasions, with adaptive mutations in the dltB gene being a widespread mechanism for doing so, according to the paper.
The dltB gene is utilised by the bacterium to produce a protein involved in making its cell wall. But “the mechanism underlying the role of the dltB mutations in adaptation to rabbits is unclear,” the paper said.
It is “worrying” to know that a single mutation could allow a bacterial pathogen to switch hosts, observed Manjula Reddy, a researcher at the Centre for Cellular and Molecular Biology in Hyderabad who studies the bacterium Escherichia coli.
Chinese astronomers spot brightest, biggest quasar powered by black hole
A team of Chinese astronomers has discovered the most luminous super massive quasar, a shining object produced by the black hole, ever found in the distant universe.
According to a new study published on Thursday in the British journal “Nature”, the quasar is 12 billion times the masses of the Sun and 430 trillion times brighter than the Sun.
The black hole, which is 12.8 billion light years from Earth, was first spotted through a 2.4 metre telescope in Lijiang in southwest China’s Yunnan Province and its existence was confirmed by follow-up studies in the United States and Chile, state-run Xinhua news agency reported.
“We were so excited when we found such a luminous object just 9 million years after the Big Bang. It will challenge theories on how black holes form and grow,” lead author Wu Xuebing of Peking University here said.
“It’s like a child growing to weigh several hundred kilograms in less than ten years. How can we explain it?” Wu said. Fan Xiaohui, professor from the University of Arizona’s Steward Observatory and a member of Wu’s team, said the discovery “presented a major puzzle” to the theories of black hole growth in the early universe.
The researchers believe that this will provide a unique laboratory to study the mass assembly and galaxy formation around massive black holes in the early universe.
“Spotting such a celestial body usually requires a 10 metre telescope. But Chinese astronomers observed it through a 2 metre telescope. It demonstrates their creativity,” said astrophysicist Chen Jiansheng with the National Astronomical Observatories at the Chinese Academy of Sciences.
Thanks to certain key technologies Wu and his team have developed in recent years, they were able to select several hundred quasar candidates from over a million celestial bodies, the report said.
“It’s like finding a speck of gold dust on a beach. We are lucky to have spotted the quasar and made follow-up observations,” Wu said.
Quasars are believed to be the brightest and most energetic objects in the universe. Since the first quasar was identified in 1963, over 200 thousand quasars have been found.
Sun exposure poses cancer risk even in the dark: study
Moving immediately into the shade does not stop sun damage as UV rays can continue damaging skin cells hours after exposure
Damage to skin cells continues for hours after spending time in the sun, according to research that uncovers a new link between sun exposure and cancer. The discovery that some of the most serious damage to skin cells may be occurring in the dark raises the prospect of new “evening after” lotions that would help limit the effect and reduce the risk of skin cancer.
The source of the “dark damage” was found to be melanin, the pigment in skin cells that normally acts as a shield against ultra-violet (UV) radiation.
The latest research at Yale University led by Prof. Douglas Brash reveals that UV light produces a cascade of chemical reactions that reacts with melanin causing one of its electrons to be “excited”. The melanin then deposits its extra energy in the surrounding tissue.
If a strand of DNA happens to be nearby, it can absorb the energy causing the double helix strand to bend and scramble the letters of the genetic code into mutations.
The more mutations skin cells accumulate over time, the higher the likelihood that one of them will turn out to be cancerous. — © Guardian Newspapers Limited, 2015
Time to lift the gloomy veil covering Indian STEAM
To a large extent, the ruling dispensations are to blame, though fat pocket industries cannot be left blameless
A pall of gloom has set in the world of Indian Science, Technology, Agriculture and Medicine (STEAM) over the last two years or so. And it has nothing (not yet) to do with who runs the government. First an across-the-board cut of over 30 per cent of the allotted budget was imposed by the previous government, leading to last-minute dropping of projects and delays in existing ones. And the present government has neither restored the cut nor added anything yet. Going by indications, it might not improve significantly. We heard a decade ago that the budget for STEAM will improve from the then 0.8 per cent of GDP to over 2 per cent in a gradual manner. Yes, it did rise to almost 1 per cent but dropped back in real terms soon. Indian efforts in STEAM are fast losing steam. So is higher education.
To a large extent, the ruling dispensations are to blame, though fat pocket industries cannot be left blameless. Unlike in Europe, Japan or the US, private industries and/or industrialists here do not have foundations or similar entities that support research by others; they at best support in-house research and development. Thus, most of us have to depend entirely on the central and state governments for support. State governments support research more by lip service than lakhs of rupees.
The earlier government had in place not one but two scientific advisory panels, had STEAM experts members in the Planning Commission, and these bodies did bring about some changes and plans for action. We are hoping the present government too would seek similar or better advice and counsel, but it is yet to be. They have so far extolled past achievements (real and imagined) rather than explore tomorrow’s science.
More often than not, ministers declare that they will open more IITs, IIMs, AIIMSs and Central Universities and so forth, often in rural places with little or no academic contacts with peers, as often happens in cities. Politicians are particularly enamoured with the success of some of these elite institutes, and think they can do the same within a few years by allotting hundreds of acre and promising billions of rupees, which may or may not come. But, bricks and mortar do not an IIT make. Today, over 30 such institutions have mushroomed across the country, and most remain headless, and the heads of already existing institutions are asked to nurse, nurture and mentor the newbies — a bureaucratic double-whammy solution. Getting the right people and letting them loose to experiment is the trick, but such autonomy is anathema for the rulers. Expert committees meet and recommend what they consider as the right men/women for the job, but the minister dismisses the recommendation and offers the job to the person of his/her choice — a classic example of ‘he who pays calls the tune.’ And we want excellence!
As Professor Amartya Sen said recently: “Academic governance in India remains so deeply vulnerable to the opinions of the ruling government.” So true. Oxford is not run by David Brown, nor is Harvard by Obama. Domain expertise, independence in decision making and autonomy — three conditions extolled by experts as essential for success need to be guaranteed. This was how the original 5 IITs and 5 central universities gained their name and fame. This is how the Indian Institute of Science has remained an outstanding institution for over 100 years. Politicians, please keep out of these!
It is worse when you call the tune, but not even pay. Over the last couple of years, the allocated budget of the government R &D labs, and grants for research project, has been cut by as much as 35 per cent. Some labs have had to pay salaries for their staff from internal funds. Researchers go around with letters that have sanctioned sums of money as grants for their research projects, but the promised money has not come yet.
It is a marvel that despite all these, many scientists and academicians continue to perform well. I know of at least half a dozen youngsters who have published world class research publications very recently. Almost all of these are patentable and can bring wealth. A couple of them, given timely (indeed immediate) support, can be fine-tuned to generate potential treatment for the rampant viral disease swine flu if a targeted programme is launched with urgency and funded. They need help and hand-holding. The NIH model in the U.S. screens such publications and helps the authors get patents and allow licensing. We have two brilliant scientists heading the Department of Biotechnology and the Department of Science and Technology. I request them to look into this aspect of screening potential breakthroughs and assist the author in patenting and licensing, and launch a program, just as China did (and succeeded with the SARS virus).
Independent India was founded and has developed largely by making friends with science. And in doing so, it relied on the wisdom and commitment of some scientists and economists who thought big. The government respected their views and acted on them, without any major interference. Plans were made, money was budgeted and spent, and we have progressed. This trend has been good to us, but in recent times this is being given the go by. The science academies have played positive roles and continue to do so, by mentoring young researchers, offering academic advice, discussing and debating with the relevant ministers. What we need is to continue to have spokespersons, even “lobbyists” as the U.S. term has it, academies and professional societies interacting with government assert themselves and taking on a role of advocacy. In such absence the budget for STEAM will continue to be sub-optimal. Mr Jaitley, continue to make friends with science and fund it. Mere 0.8 per cent of GDP will not do. Make it 2 per cent and make it in India. Tabee to Acche Din Aayenge.
Question Corner: Reflected sunlight
Can sun rays reflected by a mirror to a solar panel generate electricity?
The sunrays emanating from sun’s outer surface due to nuclear fusion take about 8 minutes to reach earth’s atmospheric region. They consist of ultraviolet, visible and infrared radiations ranging from 100nm (nanometre) to 100,000 nm. The visible rays ranging from 250nm to 800nm (violet to red) reach the earth’s spherical surface effectively. This range contains 45 per cent of the total solar radiation energy reaching the planet’s ground surface. This visible sunlight generates photovoltaic (PV) current on hitting a solar panel.
The reflective mirror changes the direction of the falling sunlight, not its quality when the reflectivity of the mirror is 100 per cent. But this does not happen in reality. The reflectivity of the mirrors ranges from 40 per cent to 95 per cent. With a mirror of good reflectivity (95 per cent) the intensity of the reflected sunlight will not be affected much. The reflected sunlight can generate PV current almost as effectively as the incident rays.
In the countries located far away from equator (Norway, Sweden etc.) the intensity (power) of sun light will be low (100-300w/m). Here larger sized plane mirror reflects the sun light on to the PV panels. An array of mirrors focuses the low intensity sunlight on panels to boost PV current generation. A big concave mirror also enhances the power of solar rays at the focus.
This week’s questions
Why do black holes have high gravity?
In humans, the lens forms an ‘inverted’ real image of the object on the retina. Then how are we able to perceive it ‘upright’?
What is the working principle of a space telescope?
Why and how do oceans absorb carbondioxide?
Why are gold ornaments packed in dark rose coloured paper while selling?
Plant clinic for diagnosing pests and infestations
The M. S. Swaminathan Research Foundation (MSSRF) along with an international organisation called CABI jointly piloted a project called plant clinic (PC) in Tamil Nadu, Puducherry and Maharashtra through the institute’s Village Resource Centres located in the regions.
The main aim of setting up such clinics is to diagnose pests and diseases in any crop and render accurate knowledge to the farming community. Basically it is a community-driven model, conducted in a common location, accessible to all categories of farmers in a village.
Farmers need guidance to distinguish the difference between pest and infestations, understand harmful effects of red labelled/banned pesticides, pest resurgence, resistance to pesticides etc.
“The clinic provides an array of technological solutions along with cultural, biological and chemical methods, which are nationally and internationally permissible, ecologically safe and environmentally sustainable for mitigating crop loss and enhancing plant health and economic benefit,” says Ms. Nancy J Anabel, Director, Information and Communications of the Institute.
The clinics are conducted fortnightly and do not cost any money according to her. Persons with agricultural background are chosen and trained by CABI as plant doctors to diagnose the issue and provide appropriate solutions. However, MSSRF encourages progressive farmers, who are reservoirs of pragmatic knowledge and traditional wisdom to be trained and enrolled in this.
A tool kit encompassing lens, microscope, laptop, projector, knife, gloves, tissue and sanitisers along with required templates to collect case history and issue prescriptions are given.
Farmers bring their affected crop samples to the clinics to recognise the problem and get technological solutions. Every farmer is provided with a prescription, detailing the case history along with recommendations.
The PC treats the crop samples with the help of the comprehensive factsheets in the local vernacular brought by the farmers.
As farmers are hungry for information regarding their crop details the role of this plant clinic is more important to help offer appropriate knowledge to them to grow healthy crops which in turn generate better revenue.
Presently about 37 plant doctors serve through 14 Plant clinics; 391 clinic sessions have been conducted till now across Tamil Nadu, Puducherry and Maharashtra, spanning 62 villages, in which more than 6,000 farmers including 992 women farmers have been reached.
Recently about 46 farmers from Varagoor village, Thanjavur District brought crop samples to the clinic and found them to be affected by rice blast.
After examining the tillers, the plant doctors recommended the right type of spray to be used. Timely application helped them save their crop with additional yield of 5.9 tons in 100 acre.
Take the case of another woman farmer, Ms. Dhanalakshmi from Pudukuppam, Puducherry, who chose agriculture as a profession, a few years back, struggled due to her no knowledge about the subject and discouragement from others.
“I was confused. I didn’t know whether I had taken the right decision. Thanks to this plant clinic concept I am able to diagnose and spot the pest and infestations if any on my paddy, plantain and mango crops,” she says.
Mr. Arunachalam, Pasupathikovil village in Thanjavur district realized an additional yield of 60 kg / half acre in Gingili crop by preventing 30 per cent yield loss from Jassids and wilt disease attack, when the rest of his fellow farmers realized a mediocre 250 kg /acre.
Similarly Mr. Gajanan Shyamraoji Wankhede, in Papal village in Amravati, Maharashtra could address leaf curling infestation in his capsicum and stem borer in his brinjal crop through one of the clinics in his region.
“We welcome farmers across the country to contact us for details on this and are ready to address their queries. If need be, more clinics like this can also be established in other parts of the country as well,” says Ms. Nancy.
Mobile phone users’ data at risk of attacks: McAfee
McAfee Labs reported that mobile malware samples grew 14 per cent during the fourth quarter of 2014, with Asia and Africa registering the highest infection rates.
Cellphones with mobile applications could be potential target of cyber attacks globally and subscribers’ data including usernames and passwords are at risk, security software maker McAfee said on Tuesday.
The failure of mobile application developers to patch critical secure sockets layer (SSL) vulnerabilities could potentially impact millions of mobile phone users, according to McAfee Labs Threats Report: February 2015.
It said that in September 2014, Computer Emergency Response Team (CERT) at Carnegie Mellon University released a list of vulnerable mobile applications and McAfee Labs in January tested the 25 most popular apps on the list.
During the tests, it was found that 18 have still not been patched despite public disclosure, vendor notification, and, in some cases, multiple version updates addressing concerns other than security.
The report said most downloaded vulnerable app in this group is a mobile photo editor with between 100 million and 500 million downloads. The app allows users to share photos on several social networks and cloud services.
“McAfee Labs researchers simulated man-in-the-middle (MITM) attacks that successfully intercepted information shared during supposedly secure SSL sessions. The vulnerable data included usernames and passwords and in some instances, login credentials from social networks and other third party services,” it said.
Although there is no evidence that these mobile apps have been exploited, the cumulative number of downloads for these apps ranges into the hundreds of millions, the report said.
“Given these numbers, McAfee Labs’ findings suggest that the choice by mobile app developers to not patch the SSL vulnerabilities has potentially put millions of users at risk of becoming targets of MITM attacks,” it added.
McAfee Labs also warned of increasingly aggressive potentially unwanted programs (PUPs) that change system settings and gather personal information without the knowledge of users.
McAfee Labs reported that mobile malware samples grew 14 per cent during the fourth quarter of 2014, with Asia and Africa registering the highest infection rates.
IISc researchers produce a superior water filter
A membrane capable of producing safe drinking water by filtering out objects at the nanoscale level and killing the commonly found pathogenic bacteria E. coli has been developed by a team led by Dr. Suryasarathi Bose, Assistant Professor, Department of Materials Engineering, IISc, Bengaluru.
The membrane is produced by mixing two polymers — poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) — that become miscible at about 220 degree C. While PVDF crystallises during cooling, PMMA does not and separates out; the PMMA is removed using a solvent. This property of selective crystallisation and separation is taken advantage of to produce a nano-porous membrane.
As the membrane is about 1 mm thick, a combination of fine pores and channels are produced when the PMMA is removed. The average pore size is 50 nm. “The blend of two polymers is known, but we have been able to use that to produce a nano-porous structure by removing the PMMA,” said Prof. Bose. The results of the work were published last week in the Journal of Materials Chemistry A.
Last year, Dr. Bose had produced a novel membrane that had micron-sized pores (0.57-0.68 microns). It was produced by mixing two polymers polyethylene (PE) and polyethylene oxide (PEO) at 180 degree C. In this case, the micron-sized pores were produced by removing the water-soluble PEO.
Unlike the micro-filtration achieved using the PE polymer, the nano-pore structure produced now has greater advantages. “It can support a reverse osmosis membrane,” he said. “It can enhance the efficiency of a RO membrane if placed before it.” The nano-porous membrane can filter the water and send semi-pure water to the RO membrane. As a result, the RO membrane will require lesser pressure to produce pure water.
The nano-sized porous structure can prevent bacteria from passing through the pores as bacteria are typically micron-sized. However, the bacteria can form a biofilm on the structure. As a result, the filter’s efficiency will be reduced within a short period.
To prevent this and to kill the bacteria, they mixed silver, titanium dioxide and carbon nanotubes to the PVDF-PMMA mixture. Due to polarity and specific interaction with PVDF, all the three added materials got embedded only on the PVDF.
The three nanoparticles serve two important purposes. First, the nanoparticles promote PVDF crystallisation at a much faster rate. As a result of faster crystallisation, defective crystals are developed. “We get nanopores of uneven sizes (50-100 nm) and these increase the flow rate of water and hasten the filtration process,” Prof. Basu said. “Under 25 psi water pressure, the flow rate is more than 2 litres per meter square second.”
The second advantage of silver, titanium dioxide and carbon nanotubes that are embedded on membrane is their ability to kill E. coli bacteria. Silver leaches in water and when the ions so released kill the bacteria by destroying the integrity of the cell and by damaging the cell proteins and terminating the DNA replication.
Titanium dioxide also kills the bacteria. Though its antibacterial property is best in the presence of UV light, the present study did not use UV light.
Carbon nanotubes kill the bacteria through direct physical contact — the roughness of the nanotubes kills the bacteria.
A combination of all the three nanoparticles was superior in killing the pathogenic bacteria E. coli.