ukpcs current affairs,samveg ias dehradun

Q. 4 जुलाई, 2014 को प्रधानमंत्री नरेंद्र मोदी द्वारा जम्मू एवं कश्मीर के किस जिले में नियंत्रण रेखा के पास उरी गांव में 240 मेगावाट की उरी-2 पनबिजली परियोजना का शुभारंभ किया गया?
A.बारामूला जिले में।
Q. हाल ही में किसकी अध्यक्षता में काले धन पर विशेष जांच दल का गठन किया गया है?
A. सर्वोच्च न्यायालय के सेवानिवृत्त न्यायाधीश एम.बी. शाह की अध्यक्षता में।
Q.  मई, 2014 को भारत के प्रधानमंत्री के रूप में शपथ ग्रहण करने के पश्चात नरेंद्र मोदी ने सर्वप्रथम 15-16 जून, 2014 के मध्य किस देश की राजकीय यात्रा की थी?
A. भूटान की।
Q. हाल ही में चर्चा में रहे आतंकवादी संगठन ‘आईएसआईएस’ का पूरा नाम क्या है?
A, ‘इस्लामिक स्टेट ऑफ इराक एंड सीरिया’।
Q. 18 जून, 2014 को जारी वैश्विक शांति सूचकांक में प्रथम स्थान पर कौन-सा देश है?
A. आइसलैंड।
Q. 10 जुलाई, 2014 को वित्त मंत्री अरुण जेटली द्वारा प्रस्तुत वर्ष 2014-15 के केंद्रीय बजट में राजकोषीय घाटा कितने प्रतिशत के स्तर पर प्रस्तावित है?
A. 4.1 प्रतिशत के स्तर पर।
Q. वर्ष 2014-15 के बजट के अनुसार क्रमशः सरकार के व्यय एवं प्राप्तियों का मुख्य घटक क्या है?
A. क्रमशः ब्याज भुगतान तथा उधार एवं अन्य देनदारियां।
Q. जुलाई, 2014 में प्रस्तुत आर्थिक समीक्षा के अनुसार वर्ष 2013-14 में जीडीपी वृद्धि दर कितने प्रतिशत के स्तर पर आकलित है?
A. 4.7 प्रतिशत के स्तर पर।
Q. 24 जून, 2014 को अंकटाड द्वारा जारी विश्व निवेश रिपोर्ट-2014 के अनुसार सबसे बड़ी निवेश प्राप्तकर्ता अर्थव्यवस्था कौन है?
A. संयुक्त राज्य अमेरिका।
Q. 30 जून, 2014 को ‘भारतीय अंतरिक्ष अनुसंधान संगठन’ द्वारा प्रक्षेपित ‘ध्रुवीय उपग्रह प्रक्षेपण यान’ ने कितने विदेशी उपग्रहों को उनकी निर्धारित कक्षा में स्थापित किया?
A. 5 विदेशी उपग्रहों को।
Q. 15-25 जून, 2014 के मध्य संपन्न कतर की राजधानी दोहा में विश्व धरोहर संबंधी वैश्विक समिति की बैठक में भारत के किस राष्ट्रीय उद्यान को विश्व धरोहर सूची में सम्मिलित किया गया है?
A. ग्रेट हिमालय राष्ट्रीय उद्यान (हिमाचल प्रदेश) को।
Q. 1 जुलाई, 2014 को किसने अमेरिकी नौसेना के इतिहास में चार सितारा एडमिरल बनने वाली प्रथम महिला होने का गौरव प्राप्त किया है?
A. मिशेल हावर्ड ने।
Q. 3 अगस्त, 2014 को चीन के किस प्रांत में 6.1 परिमाण तीव्रता का भूकंप आया जिससे जन-धन की व्यापक क्षति हुई?
A. यून्नान प्रांत में।
Q. 14-16 जुलाई, 2014 के मध्य छठां ब्रिक्स शिखर सम्मेलन कहां संपन्न हुआ?
A. फोर्टालेज़ा एवं ब्रासीलिया (ब्राजील) में।
Q. जून, 2014 में जी-7 देशों का 40वां शिखर सम्मेलन कहां संपन्न हुआ?
A. बेल्जियम की राजधानी ब्रुसेल्स में।
Q. हाल ही में आसियान देशों का 24वां शिखर सम्मेलन कहां संपन्न हुआ?
A. म्यांमार की नई राजधानी नाय प्यी टा में।
Q. 18 जुलाई, 2014 को जारी वैश्विक नवाचार सूचकांक-2014 के अनुसार भारत का 143 देशों की सूची में कौन-सा स्थान है?
A. 76वां स्थान।
Q. 23 जुलाई से 3 अगस्त, 2014 के मध्य ग्लासगो में संपन्न 20वें राष्ट्रमंडल खेलों में भारत को कितने पदक प्राप्त हुए और वह किस स्थान पर रहा?
A. 64 पदक एवं 5वां स्थान।
Q. वर्ष 2018 में 21वें राष्ट्रमंडल खेल कहां आयोजित होंगे?
A. गोल्ड कोस्ट सिटी (ऑस्ट्रेलिया में)।
Q. हाल ही में चर्चित इबोला वायरस सर्वप्रथम किस देश में प्रकाश में आया था?
A. गिनी में।
Q. इबोला वायरस से अफ्रीका महाद्वीप का कौन-सा हिस्सा सर्वाधिक प्रभावित है?
A. पश्चिमी।
Q. जुलाई, 2014 में मालिन गांव भूस्खलन के कारण पूरी तरह तबाह हो गया, यह गांव महाराष्ट्र के किस जिले में स्थित है?
A. पुणे जिले में।
Q. 1 अगस्त, 2014 को विमोचित नटवर सिंह की आत्मकथा का क्या नाम है जो काफी चर्चा में रही?
A. ‘वन लाईफ इज नॉट इनफ’(One Life Is Not Enough)।
Q. जुलाई, 2014 में जारी मानव विकास सूचकांक में 187 देशों में भारत को किस स्थान पर रखा गया है?
A. 135वें स्थान पर।
Q. 20 जुलाई, 2014 को किसे प्रधानमंत्री नरेंद्र मोदी का व्यक्तिगत सचिव नियुक्त किया गया है?
A. संजीव कुमार सिंगला को। प्रधानमंत्री के एक अन्य व्यक्तिगत सचिव राजीव टोपनो हैं।
Q. जुलाई, 2014 में बाल मजदूरी को वैधानिक बनाने वाला विश्व का पहला देश कौन है?
A. बोलीविया।
Q. 13 जुलाई, 2014 को किस देश की फुटबॉल टीम ने फीफा विश्व कप जीता?
A. जर्मनी ने।
Q. हाल ही में किस राज्य ने राज्य पुलिस बल में महिलाओं को 33 प्रतिशत आरक्षण प्रदान करने की घोषणा की?
A. गुजरात ने।
Q. जुलाई, 2014 में संपन्न इंडोनेशियाई राष्ट्रपति चुनाव में किसे राष्ट्रपति निर्वाचित किया गया है?
A. जोको विडोडो को।
Q. 23 जून से 6 जुलाई, 2014 के मध्य संपन्न वर्ष 2014 की विम्बलडन चैंपियनशिप के क्रमशः पुरुष एकल एवं महिला एकल का खिताब किसने जीता?
A. क्रमशः नोवाक जोकोविक एवं पेत्रा क्विटोवा ने।
Q. जून, 2014 में वर्ष 2013 के ज्ञानपीठ पुरस्कार के लिए किसे चुना गया?
A. केदारनाथ सिंह को।
Q. 15 जुलाई, 2014 को गांधी शांति पुरस्कार, 2013 किसे प्रदान किया गया?
A. चंडी प्रसाद भट्ट को।
Q. 18 जुलाई, 2014 को किसे पश्चिम बंगाल का राज्यपाल नियुक्त किया गया है?
A. केसरी नाथ त्रिपाठी को।
Q. 3 से 4 अगस्त, 2014 के मध्य प्रधानमंत्री नरेंद्र मोदी किस देश की आधिकारिक यात्रा पर रहें?
A. नेपाल की।

India is an amazing contry with unlimited potential: Zuckerberg

Prime Minister Modi is committed to connecting villages online and we are excited to see how Facebook can help," the Facebook co-founder said

Seeing exponential growth potential for Facebook in India, its co-founder Mark Zuckerberg on Thursday said he will discuss with Prime Minister Narendra Modi ways to connect villages with the digital world.

The CEO of the California-headquartered firm, who is on his first visit to India, said he is excited to help the government in its ambitious Digital India programme.

“India is an amazing country with unlimited potential. It is a place of big ambitions and Facebook is deeply committed to the country. We see lot of growth for us here. Tomorrow I’m meeting the Prime Minister. He is committed to connecting villages online and we are excited to see how Facebook can help,” Mr. Zuckerberg said here.

India has about 243 million Internet users and have 100 million plus Facebook users, but there are over a billion people in the country who do not have access to the net, he added.

He is the third high profile CEO of a US-based firm, after Amazon’s Jeff Bezos and Micrsoft’s Satya Nadella, to visit India in last few days.

Mr. Zuckerberg announced that Facebook is creating a $ 1 million fund to help developers develop apps for farmers, migrants and women. This will be a contest to drive new apps and services in local languages.

“Since 2007, Facebook has been working on new apps and services in local languages. About 65 per cent use Facebook in a language other than English, including 10 Indian languages,” he added.

On barriers in Internet penetration, he said: “There are three major barriers to connectivity network, affordability and content.”

Mr. Zuckerberg, counted among the youngest tech billionaires, said free basic internet access should be like dialing 911 in the US or 100 in India.

Technology has to serve the society, he said adding that connectivity cannot be a privilege of the rich and powerful.

“When the benefits of technology are shared across the whole society, we can make the big leap. Because India has embraced science, the next generation has the opportunity to bring the world to India and India to the world,” he added.

Mr. Zuckerberg said through Internet.org, the industry aims to make Internet access affordable for people across the globe.

Focused on enabling the next five billion people without Internet access to come online, the founding members of the project include Facebook, Ericsson, MediaTek, Nokia, Opera, Qualcomm and Samsung.

The partners are collaborating on developing lower-cost, higher-quality smart phones and deploying Internet access in under-served communities.

French novelist Patrick Modiano wins Nobel in Literature

Patrick Modiano of France, whose work focuses on the Nazi occupation and its effect on his country, was awarded the Nobel Prize in Literature on Thursday.

The Swedish Academy gave the 8 million kronor ($1.1 million) prize to Modiano “for the art of memory with which he has evoked the most ungraspable human destinies and uncovered the life—world of the occupation.”

Modiano, 69, whose novel “Missing Person” won the prestigious Prix Goncourt in 1978 was born in a west Paris suburb two months after World War II ended in Europe in July 1945.

Jewishness, the Nazi occupation and loss of identity are recurrent themes in his novels, which include 1968’s “La Place de l’Etoile” later hailed in Germany as a key Post—Holocaust work.

Modiano owes his first big break to a friend of his mother’s, French writer Raymond Queneau, who first introduced him to the Gallimard publishing house when he was in his early twenties.

Modiano, who lives in Paris, is known to shun media, and rarely accords interviews. In 2012, he won the Austrian State Prize for European Literature.

Canadian writer Alice Munro won the literature prize last year.

This year’s Nobel Prize announcements started Monday with a U.S.—British scientist splitting the medicine prize with a Norwegian husband—and—wife team for brain research that could pave the way for a better understanding of diseases like Alzheimer’s.

Two Japanese researchers and a Japanese—born American won the physics prize for the invention of blue light—emitting diodes, a breakthrough that spurred the development of LED as a new light source.

The chemistry prize on Wednesday went to two Americans and a German researcher who found new ways to give microscopes sharper vision, letting scientists peer into living cells with unprecedented detail to seek the roots of disease.

The announcements continue Friday with the Nobel Peace Prize and the economics award on Monday.

As always, the awards will be presented on Dec. 10, the anniversary of prize founder Alfred Nobel’s death in 1896.

Sardar Patel Urban Housing Mission: Housing for all by 2022

The Centre will soon roll out the ‘Sardar Patel Urban Housing Mission’, which will ensure 30 million houses by 2022, mostly for the economically weaker sections and low income groups. On Thursday, Union Minister for Housing and Poverty Alleviation and the Urban Development M. Venkaiah Naidu said the

Mission is in keeping with Prime Minister Narendra Modi’s direction of Har Parivar ko Ghar (a house for every family).

To be built through public-private-partnership, interest subsidy and increased flow of resources to the housing sector, these houses are also aimed at creating slum free cities across the country. “Government’s urban development and housing initiatives will aim at social inclusion so as to benefit all sections of urban residents including slum dwellers,” said the Minister, speaking at ‘World Habitat Day - Voices from Slums’ a programme, organised by the HUPA Ministry.

On the steps being initiated to replace slums with low cost houses, the Minister said the focus is on in-situ development of slums by encouraging vertical construction. “Slum dwellers are entitled to not only a roof over their heads but also, a safe and healthy environment, affordable transport and energy, safe and clean drinking water, employment and empowerment,” the Minister said.

An investment of about Rs. 50 lakh crore would be required over the next few years for various initiatives including Housing for All (Rs. 22.50 lakh crore), urban infrastructure development (Rs. 16.50 lakh crore), urban sanitation (Rs. 62,000 crore) and building smart cities, the Minister said.

Politics without opposition

In the new political mode, the universalism and integrative capacity of the development discourse sits well with the homogenisation of the cultural sphere, and therefore with the project of radical Hinduisation

The new political dispensation is caught between two visible political discourses that do not look compatible at the moment but the political experiment to find a middle ground that obliterates the tension between them is on. The conflict is between development and governance on the one hand and communalism on the other, where the former is ostensibly universal and all-inclusive, while the latter is divisive, discriminatory and sectarian.

The possible way to balance this is to browbeat the religious minorities in terms of their claims to an independent cultural identity and visible religious practices; thus the announcement by the Rashtriya Swayamsevak Sangh (RSS) chief that “all Indians are Hindus” or Narendra Modi’s refusal to wear the skullcap, while making appeals to Muslims and attempts to reach out to them to be a part of the new development agenda. Therefore, it is important to claim that Muslims in Gujarat are better off than under any other government that claims to be secular. This resonates with the slogan that the Bharatiya Janata Party (BJP) went to the polls with — “Sabka Saath Sabka Vikas.”

Onus on minorities

Cultural subjugation is sought to be made good through economic integration. This trade-off also lays the onus on Muslims to carry out internal reforms within their community to be eligible to be a part of the modern education and economic opportunities available due to ongoing market reforms and efficient governance. Here the claims to a separate cultural identity begin to look out of place since it can be very easily perceived not only as anti-development but also as anti-national in its “refusal” to get integrated, thereby becoming obstructionist to modern development.

This further leads to the BJP’s claims that while it is prepared to integrate the religious minorities, it is they who are unprepared to do so. If there is tension between communities or between the discourse of the government and the minority community, the blame can squarely be laid on the latter. In this new mode, the universalism and integrative capacity of the development discourse sits well with the homogenisation of the cultural sphere, and therefore with the project of radical Hinduisation. Further, secular discourse here signifying protective policies and social welfare schemes for specific communities can easily be made to look like appeasement and unsustainable doles, in place of an efficient and robust economy. Secularism is therefore an outmoded discourse of the Nehruvian era that holds back economic advancement.

This logic however does not or cannot be limited to the religious minorities but needs to necessarily be inclusive of the Other Backward Classes (OBC), Dalits and also tribals. In only such an inclusion can the discourse look universal and all encompassing. It is in order to make this adjustment that the BJP has to reach out to OBCs, Dalits and tribals. It is this project which is visible in the anointment of Mr. Modi as the prime ministerial candidate of the BJP, signifying a process of the Bahujanisation of the Hindu right-wing party. The BJP, as is widely believed, is the first party to have taken upon itself to make an OBC the Prime Minister, unlike all other mainstream political parties, including the Left parties. Representation trumps all other forms of pursuing social justice. It is to further this very mode of pursuing a new kind of politics that Mr. Bhagwat has recently and for the first time publicly supported the policy of reservations for the Scheduled Castes and Scheduled Tribes at an event in Delhi marked by the release of three volumes on the history of three Scheduled Castes that included the Balmikis, the Khatiks and the Charmakars.

Equality is alien

These volumes have been authored by Vijay Sonkar Shastri, a Dalit and a former MLA with the BJP from Uttar Pradesh. They broadly make the claim that there was no untouchability in the Vedic ages and it was a later day practice that came into existence with the “Muslim invaders.” The volumes further claim that while the Khatiks were originally Brahmins, the Balmikis and the Charmakars were Khastriyas. Since these were the warrior communities which refused to convert to Islam, they were assigned menial jobs such as scavenging, dealing with leather and sweeping. Some of them were prisoners of war who were forced to do manual work and forcefully segregated from the rest of the society, and thereby introduced to the hitherto unknown practice of untouchability.

The volume on Charmakars claims that the word “chamar” is an Arabic word, denoting those dealing with leather work. It was with the advent of the British, colonial rule and the process of codification, that the practice of untouchability against the depressed classes came to be rigid. The volumes make a further claim that Buddhism, Sikhism and Jainism are all variants of Hinduism; therefore, there were no forced conversions in any of these religions; in fact, even Brahmins willingly converted to these “forms” of practising Hinduism. The volumes make a further plea to write a more detailed history of the tribals also (which the RSS has already taken up). As these were the communities that also resisted attempts at conversion but were unable to resist the might of the “Muslim invaders,” they chose to run away into the forests in order to protect themselves. It is these Hindu communities that began to inhabit forests that are the tribes of today and who have been deprived of the benefits of modern development.

The volumes suggest an interesting way out of the current logjam. They argue that the idea of equality is alien to our culture as it promotes antagonism, and what our civilisation is based on is cultural diversity. Therefore, what we need is not equality — Samantha, but Samarastha — social harmony. The volumes further suggest that by repeatedly referring to certain castes as being Dalits, we only further reinforce their demeaned status. Instead, we need to look at the history of how they have come to be one and pull them out. Therefore, we need to preserve our cultural and community differences but also fight against untouchability, resonating the Gandhian strategy (which partly explains the newfound love of the current dispensation for Gandhi). We also need to celebrate the glorious legends of/in each of the castes in order to restore to them their original pride in Hindu society. These volumes clearly reflect a move towards a de-Brahmanising of the Hindu religion by finding a place of pride for Dalit castes, while blaming the Muslim rulers and not the Hindu sacred scripts or ritual hierarchy or other Brahmanical practices.

New opportunities

While development and governance promise to be inclusive of everyone including the tribals and also Muslims — even if they are reminded against brandishing their religious symbols as that alone is arguably the cause of communal tensions — a de-Brahmanised Hinduisation that talks of Samarastha is sought to be inclusive of all caste groups.

The recent shift in leadership in the BJP is a pointer to this, and undoubtedly presents new opportunities to the caste groups that were perhaps kept at some distance in the past by the BJP that was known as the Brahmin-Bania party. It was in this context that Dalit-Bahujan scholar Kancha Ilaiah, in a recent interview, remarked that “if Modi starts the liberation of backward classes, castes and tribes, he can become a cult-figure for backwards” and can be comparable to Abraham Lincoln. With no effective imagination outside modern development and growth, and little reason to have effective opposition to a more representative and de-Brahmanised Hindusim pursued by the BJP-RSS combine, there is a clear possibility of moving towards a new kind of politics without opposition. There is no doubt that the current dispensation is being reasonable in expecting itself to be playing a long innings.

How we get a sense of place and navigate

Results from functional imaging (fMRI) studies on human brains demonstrate the existence of place cells and grid cells

The Nobel Prize in Physiology or Medicine 2014 has been divided among three scientists with one half being awarded to John O'Keefe of University College, London, and the other half shared by May-Britt Moser of the Centre for Neural Computation, Trondheim, Norway and Edvard I. Moser of Kavli Institute for Systems Neuroscience, Trondheim, Norway “for their discoveries of cells that constitute a positioning system in the brain.”

Their discoveries tell us how we are able to get a sense of place in any given environment and an ability to navigate. If the sense of place gives us a perception of the position with respect to the environment, the ability to navigate is linked to the direction and distance from the previous positions. In effect, the two together provide us with an internal positioning or “inner GPS” with respect to the environment.

American experimental psychologist Edward Tolman was the first to propose, as early as 1948, a concept of a map-like representation of a place in the brain. However, he did not propose where these functions were located in the brain and how they functioned.

Place cells

The first success in understanding the sense of place came from O’Keefe’s experiments using freely moving animals. The cellular activity in the brain of these animals as they moved allowed him to find the unique place fields and relate the neural activity to the sense of place. The neural activity was seen in the hippocampus of the brain.

O’Keefe also showed that a specific rearrangement of place cells in different settings, called remapping, could be learned, the reason why we are able to place ourselves in an environment and navigate after some time. In effect, the place cells acted as a substrate for memory process, where memory of an environment was based on specific combination of place cells.

Seminal work

Although O’Keefe was not the first to propose that the hippocampus was responsible for spatial navigation, it was received with scepticism. It soon came to be accepted that the hippocampus contains the mental map or inner map. The discovery of place cells and the demonstration that they represented a mental map, together with the proposal that the hippocampus containing the neural cells provides the inner map that store information of the environment were seminal.

O’Keefe’s work led to a flood of studies, both experimental and theoretical, including those of the Moser couple.

Despite the notion that the place cells originated within the hippocampus, May-Britt Moser and Edvard I. Moser went beyond O’Keefe’s work. They looked for areas in the brain outside the hippocampus where place cell firing was generated. After all, the entorhinal cortex, which lies on the dorsal side of the hippocampus, provided a major input to the hippocampus.

According to the Nobel Prize site, “A large part of the output from the entorhinal cortex projects to the dentate gurus in hippocampus, which in turn connect to the region in the hippocampus called CA3, and further to CA1 in the dorsal hippocampus.” The place cells are found in the CA1.

The two scientists were prompted to look for place coding cells in the entorhinal cortex as it was directly and reciprocally connected to CA1 through CA3. Like others before them, May Britt Moser and Edvard Moser established that entorhinal cortex contained cells that “shared characteristics” with the place cells in the hippocampus.

Grid cells

Looking for place cells in the entorhinal cortex, these two researchers discovered a novel cell type — grid cells. The gird cells together with the place map provide the inner map. If the place cells provide the spatial map, the grid cells provide the navigation or path integration system.

A single grid cell fires when an animal reaches particular locations in an arena. These locations are arranged in a hexagonal pattern. They also showed that the grid formation did not arise out of a simple transformation of sensory or motor signals, but out of complex network activity.

“They concluded that the grid cells were part of a navigation or path integration system. The grid system provided a solution to measuring movement distances and added a metric to the spatial maps in the hippocampus,” notes the advanced information provided by the Nobel Prize site.

They also found that the grid cells were “embedded in a network in the medial entorhinal cortex of head direction cells and border cells, and in many cases, cells with a combined function.” The head-direction cells are like a compass that becomes active when the animal’s head turns in certain direction. The border cells, on the other hand, provide a reference to the wall or boundary of a room or environment.

All the three cells — the grid cells, the head-direction cells and border cells — projected to the hippocampus place cells.

The Mosers’ discovery of the gird cells, its spatial metric co-ordination system and the identification of the medial entorhinal cortex as a computational centre for spatial representation has been a breakthrough.

Though the presence of place cells and grid cells were identified experimentally in rats, such a system is found in other animals too, including humans. The hippocampal-entorhinal structure is found in all mammals and a hippocampal-like structure is found in non-mammals with navigational capacity. This suggests that the functional and robust grid-place cells system in vertebrates must have been conserved.

The existence of place-like cells in the hippocampus and grid-like cells in the entorhinal cortex has been identified in the human brains of patients with epilepsy. Results from functional imaging (fMRI) studies on human brains have provided support for the existence of place cells and grid cells in humans. Also, studies of patients undergoing neurosurgery have strengthened the evidence of place cells and grid cells in humans.

The discovery of place cells and grid cells and their role in spatial mapping and navigation have great implications in medicine. The reason why patients with Alzheimer’s disease often lose their way and cannot recognise the environment becomes clear as the hippocampus and entorhinal cortex, where the place cells and grid cells are located, are frequently affected at an early stage.

A prize for illuminating lives with blue light

This year the Nobel prize in physics goes to Isamu Akasaki, Meijo University and Nagoya University, Hiroshi Amano, Nagoya University, and Shuji Nakamura, University of California, Santa Barbara, for inventing the blue light emitting diode (blue LED) 20 years ago.

After the announcement, when asked how he felt on being awarded the Nobel Prize, Akasaki said “It’s unbelievable.”

“Their inventions were revolutionary. Incandescent bulbs lit the 20th century; the 21st century will be lit by LED lamps,” notes a statement by the Royal Swedish Academy of Sciences, which awards the Nobel Prizes.

This is a prize that would be after Alfred Nobel’s own heart, because he had intended that the prizes should go to those who have “conferred the greatest benefit to mankind.”

The blue LED forms the long-awaited third in the set (red, green were already produced) of coloured LEDs that can together produce white light, in a way that is environment-friendly and energy-efficient. The blue LED can also be made to excite a phosphor into emitting red and green lights, with the mixture yielding white light.

LEDs basically consist of a junction of p-type (electron deficient or hole rich) and n-type (electron rich) semiconductors. When a voltage is applied across this junction, the holes and electrons flow across the junction and recombine, in the process, releasing light.

They do not use mercury or any such gas as is used in the fluorescent light. This makes them environment friendly. They do not require a filament to get heated and glow to shed light unlike the case of the tungsten light bulb.

In contrast to the incandescent bulbs and fluorescent lamps, the LEDS directly convert electricity to light particles. As a result, there is greater efficiency; in the other two cases, a great part of the electricity gets converted to heat.

The colour of the light emitted by the LED when voltage is applied may range from infrared to ultraviolet. Red and green LEDs have been around since the late 1950s, and these have been used extensively in digital displays and the like.

Junctions that emitted weak blue light when excited by an electron beam were made by Akasaki’s group in the late 1980s. Yet, the extraordinary difficulty in making LEDs that give off blue light of significant strength delayed the fabrication of the blue LED to the early 1990s, and this made it a prizewinning effort.

In the 1950s, the material that was commonly used to produce LEDs was Gallium Phosphide (GaP) with dopants (added impurities) like Zn-O or N. These gave out red and green light.

This led to the commercial manufacture of red and green LEDs in the 1960s. However, blue light still remained a challenge and a quest. After some research, it came to be believed that Gallium Nitride (GaN) was the material that would enable development of blue LEDs. But GaN crystals were notoriously difficult to grow in the lab.

The quest for fabricating the blue LED starting from GaN took shape in the 1950s itself. Researchers at the Philips Research Laboratories had produced light of a wide range of wavelengths from GaN.

However, the material was in a powder form and could not be grown into crystals to create p-n junctions So many researchers were giving up GaN and moving back to further research compounds such as GaP. Even as late as 1973, fabricating single GaN crystals and providing adequate p-doping remained the two great obstacles in the path of making the blue LED.

GaN crystals

It was into this scenario that Isamu Akasaki entered, in 1974. Working first at Matsushita Research Institute in Tokyo and later as a professor, with Hiroshi Amano and coworkers, in Nagoya University, he continued his research. In 1986, they succeeded in growing high-quality single crystals with good optical properties on a base of sapphire, for the first time. Shuji Nakamura, the other Nobel Prize awardee, who was working at Nichia Chemical Corporation, developed a similar method and published these results in a 1991 paper.

Second challenge

Still, the second major challenge remained, which was that making an LED requires a p-n junction. While it was easy to form the electron rich n-layer out of crystalline GaN, producing the electron deficient p-layer remained a problem.

By the late 1980s, Amano, Akasaki and coworkers seemed to have cracked this problem, but almost accidentally. They observed that when Zn-doped GaN was viewed under a scanning electron microscope, it seemed to emit more light. This implied that the p-doping had been improved and that a p-n junction had formed. Similarly, shining an electron beam on Mg-doped GaN showed better p-doping properties.

The duo did not however understand why this was happening and were therefore unable to exploit it. This was explained a few years later by Nakamura and coworkers: Acceptor impurities such as Magnesium or Zinc, which normally give rise to p-type conductivity, are trapped by hydrogen during the manufacturing process.

They therefore cannot perform their roles as providers of holes. When the acceptors get excited by electrons, they get activated and the holes are released.

Nakamura used a different approach to produce the p-layer. He found a simple heat treatment (annealing) would activate the acceptors, thus making the p-layer active.

In order to make the LED more efficient, both Akasaki’s and Nakamura’s teams in the 1990s moved on from simple p-n junctions to fabricating more complex, layered structures known as double heterojunctions.

In such multi-layered structures, the recombination of holes and electrons occurs more efficiently and with minimal losses. Having succeeded in the fabricating the basic structures, the groups then started work on to improving the efficiency of the heterojunctions.

In 1994, Nakamura and coworkers fabricated an efficient double heterojunction consisting of a combination of Indium- and Aluminium-doped Gallium nitride (InGaN/AlGaN).

This directly led to the development of efficient blue-LEDs. The teams did not stop there, they went on to develop more applications, such as blue laser emissions based on GaN, which was observed in 1995-96.

This application has advanced the technology for storing music, pictures and movies.

Today, LED lights are used in smart phones and lamps. White light from LEDs is more power-efficient than from other sources: If the amount of light flux produced per unit of power supplied is 16 for a tungsten bulb, and 70 for a fluorescent bulb, it is 300 for a LED supplied source. This would drastically lower our power consumption if LED lights are used more.

Solar-powered LED lights are also taking the world by storm. From providing illumination to possible future applications such as generating UV light for treating bacteria-infested water, the blue LED has come to stay.