Citation: Cryogenic Phonon Scintillators to Help in Search for Dark Matter (2006, March 17) retrieved 18 August 2019 from https://phys.org/news/2006-03-cryogenic-phonon-scintillators-dark.html What do WIMPs and MRIs have in common?Besides being acronyms, both the dark matter candidate and the medical diagnostic technique could benefit from the next generation of cryogenic scintillators being developed. While physicists are primarily focusing on the search for dark matter and answers to how the universe is built, they’re creating a detector with superior energy resolution and distinguishing capabilities that could have repercussions beyond the questions of the universe. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. This cryogenic detector can distinguish space background radiation from the recoil energy of a WIMP interacting with the nuclei of normal matter. Labeled parts: 1 – scintillating crystal, which physicists measured different materials for best fit, 2 – reflector, 3 – light detector, 4 and 4’ – thermometer calorimeter film, which can sense a small temperature difference caused by energy released during WIMP events, 5 – particle, 6 – phonons, which result when the crystal vibrates, and 7 – light. Image credit: Mikhailik, V. B. and Kraus, H. Based on the way that galaxies spin, cosmologists believe that a form of matter which doesn’t reflect light must exist in the universe. Not only does this dark matter affect how galaxies spin, but a particular amount of it would balance out the total mass of the universe so that it’s not so light that one day it collapses back in on itself. Cosmologists wonder what dark matter could be made of that makes it so enigmatic and massive, and theorists favor a type of particle called a WIMP (Weakly Interacting Massive Particle). On very rare occasions, WIMPS may interact with nuclei in normal matter and impart a tiny amount of recoil energy to the nuclei.Although physicists may be able to detect this recoil energy, they face a couple of large challenges. For one, the amount of recoil energy is so small that current detectors haven’t been able to pick up any signals. Also, a background of space radiation and cosmic rays interfere with the energy of the nuclei, and make it difficult for detectors to distinguish the two sources. Physicists V. Mikhailik and H. Kraus from the University of Oxford are looking for materials that might work for a new type of detector called a cryogenic phonon scintillator detector (CPSD). As they report in a recent Journal of Physics D: Applied Physics, CPSDs could have superior energy resolution and the ability to discriminate between particles and radiation, and possibly be able to detect rare WIMP interactions. The high hopes for the new CPSDs stem from the way that these detectors work. CPSDs are constructed of crystals that increase in temperature when energy is deposited in them. Because these scintillating crystals can distinguish the subtlest temperature differences at the lowest temperatures, CPSDs operate optimally at temperatures close to absolute zero (in the 10-15 millikelvin range, or nearly –459°F) for the best chance of detecting WIMP events. Since operating CPSDs at extremely low temperatures is an entirely new area of research, Mikhailik and Kraus experimented with different types of materials to determine which give sufficient light at extremely low temperatures. At the same time, the materials must have very low intrinsic radioactivity in order to discriminate between different types of radiation. “In the first phase of the experimental search for WIMPs, a few CPSD detectors made of CaWO4 crystals (material which is used worldwide as x-ray screen in medical diagnostics) have already been tested and delivered excellent results,” Mikhailik told PhysOrg.com. “The next experiment will plan to use different scintillation targets with a total mass of about 100 kg, which should allow verification of a WIMP signal.”The physicists’ deeper understanding of the potential of CPSDs at low temperatures also has applications in fields such as medicine and security inspection. For example, CPSD technology could enhance image quality in diagnostic tools and reduce a patient’s radiation doses. CPSDs at low temperatures could also pick up signals from neutrons and use their ability to penetrate metal shielding made of heavy nuclei, which interact predominantly with the lighter nuclei in materials of interest. “Apparently the search for cryogenic scintillators today is the science-driven initiative that will prepare the grounds for technological progress in respective areas tomorrow,” wrote Mikhailik and Kraus.Citation: Mikhailik, V. B. and Kraus, H. Cryogenic scintillators in searches for extremely rare events. J. Phys. D: Appl. Phys. 39 (2006) 1181-1191.By Lisa Zyga, Copyright 2006 Physorg.com
Month: August 2019
Citation: Monkeys demonstrate self-awareness in computer game (2011, February 22) retrieved 18 August 2019 from https://phys.org/news/2011-02-monkeys-self-awareness-game.html The study was carried out by Professor John David Smith of the Department of Psychology at the State University of New York and Georgia State University’s Dr Michael Beran, and the results were presented at the American Association for the Advancement of Science (AAAS) meeting in Washington DC, at a session organized by the European Science Foundation.The macaques were taught to decide if the density of a small box on a computer screen was either sparse (S) or dense (D). If they used the joystick to move the box to the correct letter a treat was dispensed, while if they made the incorrect choice they got no treat and the game paused. They could avoid the pause in the game if they instead moved the box to a third option, a question mark, if they were unsure of the density of the box.The results showed the monkeys preferred to pass and move on by selecting the question mark if they were unsure of the correct answer. This option avoided the pause and allowed them to get to the next treat more quickly but did not result in a treat.Other studies have shown that human subjects also use the pass option if presented with similar problems they find too difficult.The results suggest the macaques, which are Old World monkeys, understood when they were uncertain and therefore liable to make an incorrect choice and were aware they did not know the answer. When capuchins, which are New World monkeys, were given the same task they did not take the pass option.Professor Smith said it is not certain if this kind of thinking ability emerged only once and only in the Old World primates, the line which leads to humans and apes, but that the ability of humans to be aware of our own thinking was “central to every aspect of our comprehension and learning.” This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further © 2010 PhysOrg.com Barbary monkeys going ape on Gibraltar (PhysOrg.com) — It has been widely assumed that only humans are aware of their own thinking, but a new study in macaques by US scientists shows some monkeys are also self-aware.
More information: O. Abah, et al. “Single-Ion Heat Engine at Maximum Power.” PRL 109, 203006 (2012). DOI: 10.1103/PhysRevLett.109.203006 (a) Diagram of the Otto cycle for the radial mode of an ion. (b) Pictograms illustrate the four individual strokes of the Otto cycle. (c) Geometry of the tapered Paul trap used to trap the ion. Image credit: O. Abah, et al. ©2012 American Physical Society (Phys.org)—As physicists work on miniaturizing devices, they will eventually run into the ultimate limit: the atom. A fundamental question in this area is whether it’s even possible to scale down a macroscale engine such as a car engine to the single-particle level, while retaining the same working principles. In a new study, a team of physicists has proposed a scheme to build a heat engine that consists of a single trapped ion that can perform a quantum version of the Otto cycle, the basis of the common four-stroke car engine. If realized, the single-ion engine has the potential to enter the quantum regime and become a tool to investigate how quantum effects alter a nanoengine’s efficiency. Citation: Can a car engine be built out of a single particle? (2012, November 30) retrieved 18 August 2019 from https://phys.org/news/2012-11-car-built-particle.html Scientists develop novel ion trap for sensing force and light Copyright 2012 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Explore further Journal information: Physical Review Letters A group of scientists from the Universities of Augsburg, Berlin, and Mainz in Germany, and of Maryland in the US, has published their proposal for a single-ion heat engine in a recent issue of Physical Review Letters. Previously, researchers have fabricated micro heat engines, but a quantum heat engine that is subject to quantum effects has not yet been realized.”Our numerical simulations, done with realistic parameters, show that the implementation of a quantum single-ion heat engine is feasible with currently available technology,” coauthor Eric Lutz of the Universities of Augsburg and Berlin told Phys.org. “Once built, this would be the smallest and the first quantum heat engine ever fabricated.”The proposed engine consists of a single ion trapped in a Paul trap with tapered geometry. The trapped ion is alternatingly coupled to two reservoirs of different temperatures that heat and cool the radial state of the ion. Heating and cooling causes the ion to move coherently inside the trap, generating an Otto cycle in which thermal energy is converted into motion. Ion movement in the axial direction corresponds to the movement of a piston in a classical engine, while ion movement in the radial direction corresponds to the gas in the cylinder.The scientists explain that the alternative coupling to the two heat reservoirs can either be switched externally or by the motion of the ion itself; in the latter case, after reaching an initial threshold amplitude, the engine would operate autonomously. Through analytical and numerical analysis, the researchers showed that the single-ion engine is capable of operating at a maximum efficiency of 30% at maximum power under certain conditions. The parameters of the engine can also be widely tuned, allowing the engine to operate at temperatures low enough to enter the quantum regime. The scientists also proposed a way to store the energy produced by the engine using a mechanism based on the Paul trap’s tapered geometry. The tapering allows energy to be stored in the axial mode and then transferred to other oscillator systems, such as separately trapped ions, so that the energy can be extracted and used to perform work.”We regard the single-ion engine as a prototype for general oscillator engines, based for instance on nanomechanical oscillators,” Lutz said. “These have already been used to fabricate microengines. When run as a heat pump, such an engine could offer an alternative method to locally cool a given mode, for instance in an ion chain or in a nanomechanical oscillator.”Since publishing their paper, Lutz and his coauthors have worked further on the design of a trap with a tapered geometry, and they are currently trying to build the single-ion heat engine. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Iberdrola builds huge wind farm in US In the aftermath of the March 2011 earthquake and tsunami, the Japanese government has turned away from nuclear power and the dangers it possesses and towards other renewable energy resources. The country plans to eventually shut down all of its nuclear plants and replace them with wind and solar plants. To that end, plans for wind farm construction have taken center stage, with this newest the most ambitious yet.Currently, the largest wind farm in the world is off the coast of Suffolk in the U.K. Called the Greater Gabbard farm, it produces 504 megawatts of power using 140 turbines. The new farm planned for Japan is expected to produce 1 gigawatt using just 143 turbines.Instead of anchoring each turbine directly to the ocean floor, the plan is to mount them on floating steel frames that will be anchored to the continental shelf below. To keep them upright, ballast will be used underneath. The plans also call for using 2 megawatt turbines, each standing 200 meters high. The site was chosen due to the existing infrastructure that had been used to transport power from the Daiichi plant before its destruction.Fukushima prefecture has stated its goal of becoming 100 percent energy self-sufficient by the year 2040. In addition to the wind farm, plans are also being drawn up for the biggest solar farm in the country.The wind farm will be paid for using money currently being collected via a feed-in tariff scheme for wind projects set up by the government – it became effective July 1, 2012. Thus far, its inception has boosted energy produced by such plants, the Japan Wind Power Association says, by 8.2 percent already. Construction of the huge wind farm is expected to be complete by 2020. Project managers say that sufficient testing has been done with the design to ensure the new farm will not be harmed by earthquakes, tsunamis or typhoons. Nysted wind farm in the Baltic Sea off Denmark. Photo by Jeremy Firestone, University of Delaware (Phys.org)—Officials in Japan have announced plans for building the largest wind farm in the world, ten miles off the coast of Fukushima – site of the nuclear disaster that followed the earthquake and tsunami that struck the island nation in 2011. Projections call for developing a wind farm capable of producing 1 gigawatt of power. Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Japan to replace nuclear plant with world’s largest wind farm (2013, January 18) retrieved 18 August 2019 from https://phys.org/news/2013-01-japan-nuclear-world-largest-farm.html © 2013 Phys.org
Kolkata: The state is ready to provide uninterrupted and quality power supply to the industries, state Power minister Sobhandeb Chattopadhyay said.He was addressing the ‘East India Energy Forum’ organised by the Merchants’ Chamber of Commerce & Industry (MCCI) at a city hotel on Friday. During his speech, the minister categorically pointed out that the power generation in the surplus in the state and his department is ready to cope with the extra burden. Also Read – Heavy rain hits traffic, flightsHe also reminded that the state is already exporting power to our neighbouring state, Bangladesh.”The state is growing fast. It is ready to accept any challenge. We are also committed to provide uninterrupted and quality power, not only to the new industries coming up to the state, but also to the households,” Chattopadhyay said.It may be mentioned here that the state government has increased the budget allocation by a few times after the Mamata Banerjee government came to power. A host of new projects have been initiated. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedAccording to the minister, the project to provide electricity to households has been done up to 99.99 percent. The state government has been carrying a subsidy of Rs 808 crore in the power sector so that the people are not overburdened, the minister said.He also said that his department is taking up big projects of laying underground electric cable connections at 75 towns across the state. It may be mentioned that the Power department has laid great emphasis on the development of renewable energy.
Kolkata: A Memorandum of Understanding (MoU) has been inked between CSIR- CMERI and New Delhi-based Electronic Sector Skill Council of India (ESSCI) to set up a ‘Centre of Excellence in Mechatronics’ at CSIR-CMERI, Durgapur.The purpose of the MoU is to meet the requirement in regard to the initiation of this ‘Centre of Excellence in Mechatronics’ and to support the skill development activities of CSIR-CMERI under CSIR Integrated Skill Development Programme. This agreement will also foster the aggregate skill development activities for the electronics sector in India with collaborative effort of these two organisations and would act as the flag bearer to many such future endeavours in enhancing the skill and subsequently creating job opportunity for the unemployed youth of the country. Speaking on this occasion, Prof Harish Hirani, Director, CSIR-CMERI stressed upon the importance of such collaboration in connection to the onward march of the ‘Skill India’ programme of the Government of India. NK Mahapatro, CEO, ESSCI deliberated on the vision of the skill council and the Government’s plan to give a boost to the electronic sector manufacturing in India.
Artists express in a variety of ways, their medium, method and techniques are different. And when backgrounds, nationalities and geographical location resemble, there are bound to be certain similarities in the way an artists moves forth towards their art. To celebrate similarities Art Beyond Borders is going to organise a group show Titled- Integrated Art ‘India and Bangladesh’ in the national Capital.There will be 20 eminent contemporary artists participating from India and Bangladesh such as Jatin Das, R B Bhaskaran, Dhiraj choudhary , Anandmoy Banerji, Swapan Das, Brinda Miller along with Rafiqune Nabi, Sheikh Afzal,Kanak Champa Chakma, Jamal Ahmed from Bangladesh to name a few. Also Read – ‘Playing Jojo was emotionally exhausting’There are more than 46 works in the show and all these works were created during the residency in Lucknow hence the influence of culture, monuments and chickankari seem evident in the works.“We hope to fill the void left behind by sub continental politicking and diplomacy ….allowing art to speak” says Sandhya Singh Parmar, executive director, Art Beyond Borders. “we aspire to bring all the eight SAARC nations on the same platform with art and cultural exchange,” she adds. Also Read – Leslie doing new comedy special with NetflixAll artists worked across a multiplicity of mediums and mechanism to bring their unique perspective through charcoal and paint. Sudip Roy’s Charulata a strong female character out of Tagore’s book, Babla Seth’s sculptures with recycled iron and nut bolts stands out among colours and charcoal, Sheikh Afzal’s fascinated with city street children’s bliss couldn’t help painting them in a Canvas.R B Bhaskaran one of the most respected and talented artist to participate in the Madras movement of the 1960’s work on life cycle, Jatin Das focuses mainly on man-woman relationships. Dhiraj Choudhary’s restless line speaks volume both in his painting as well the drawings. Moniruzzaman’s Ganga Jamuni showcases the old unspoken Tahjeeb of lucknow which city has hence been proud of. Rafiqun Nabi’s “Family” portrail of under section of the society with his straight lines speaks volumes on his mastery of brushes and colours. Kanak Champa’s tribal girl’s face half lit and half darkened looks at your face, Maddona by Rokeya, her expressions in colours make women issues dynamic. Gomati by Swapan Das awakens the effects of global warming and state of River Gomati.It’s an amazing effort of Art Beyond Borders to put together such brilliance of these brilliant artists from India and Bangladesh,they truly represent the ideology of promoting creativity and diffusion of culture and and the art, initiating the interaction between local and international artists. Art Beyond Borders is a voyage in India for fostering an interactive residency programme for artists from SAARC nations. A six day workshop held in Lucknow last year produced these magnificent master pieces being show cased at the gallery.When: November 27-30 Where: 1AQ, Qutub Minar, Mehrauli Road
Roxy Arora’s debut novel “Jihad in My Saffron Garden” published by Prabhat Prakashan was launched by film director and producer Anurag Kashyap at Oxford Book Store, Connaught Place in the national Capitol recently.According to the author, the journey of putting down her feelings into words started off in the year 2015. The communal riots and clashes of Jammu and Kashmir compelled her to write about it. She has closely observed the miserable life of people who suffer as a result of these communal clashes. Also Read – Add new books to your shelf”I know what it is to be persecuted; I know what it is to leave everything behind and to start again. I have witnessed these in Kuwait and England.” She said. When asked why she has chosen Jammu and Kashmir as the setting, she replied, “Every summer holiday, as a kid I used to visit Kashmir. I was spellbound by the beauty of that place. So when I thought of writing, I could not think of writing about a place other than Kashmir.”She also explained the reason behind keeping the word “Saffron” in the book’s title, “When I decided to write about Kashmir, I wanted to break away from the quintessential image of the land, which is always about the Dal Lake and houseboats. But I think there is actually nothing more beautiful than those saffron gardens, especially when the flowers are in full bloom. I’ve always been an admirer of natural beauty so I wanted the flowers to be with me.” Also Read – Over 2 hours screen time daily will make your kids impulsiveDr Roxy Arora denied calling it an autobiographical novel. According to her it is a pure work of fiction. When she started writing, she thought it would be a romantic thriller, because of her love for spies’ novel and Robert Ludlum. She also wanted to portray the problem in Jammu and Kashmir in a more serious way. She wanted to express the patriotism in each and every armed force member who is serving the state, so she has added a thriller element to it without making it too political. She has dedicated the book to the Indian Armed Forces. Dr Arora appeals for global peace, religious tolerance and mutual trust through this novel. She has also raised a question for all to ponder upon – “Can’t we have a Kashmir like before?” The lead characters of her story Roshina Kapoor and Aafaq Qazmi give priority to love and humanity before any social element in spite of their religious differences. Dr Roxy Arora in her novel has given a message that no religion preaches violence and that it is high time for people to join hands and appeal for global peace, unity and integrity.During the book launch Anurag Kashyap praised the author for stepping out of her comfort zone as she is a doctor by her profession and doing something different. He found it very inspirational. “Somewhere it gives hope and it gives passion to everyone, kudos to that,” he said.
Advocating the use of culinary diplomacy to strengthen international relations, 18 chefs of Heads of State from across the globe recently came together for the Annual General Assembly of ‘Le Club des Chefs des Chefs’ (CCC) in the national Capital.It is the group’s first meeting in India since its inception in 1977 in Paris by French chef, Gilles Bragard. Touted to be world’s most exclusive gastronomic society, the group aims to use food as a bridge between cultures and societies. “If politics divides people, a good table always gathers them. Chefs are great diplomats and good food helps in easing negotiations,” Bragard said at a press conference, hosted by The Imperial. Also Read – Add new books to your shelfBragard and other chefs of the club visited the Rashtrapati Bhawan kitchen, where they relished popular Indian street foods like golgappas and alootikkis, cooked up by Montu Saini, Executive Chef to the Indian President, Pranab Mukherjee. They also tried their hands at making jalebis. “It is about exchange of culinary skills. I would like to connect it to Prime Minister Narendra Modi’s ‘Make in India’ programme, where I am showcasing India’s culture to the rest of the world,” Saini said. Also Read – Over 2 hours screen time daily will make your kids impulsiveThe visiting members including Cristeta Comerford, Chef to the President of the United States of America, Indo-Canadian Neil Dhawan, who is Chef to the Prime Minister of Canada and Mark Flanagan, Chef to the Queen of the United Kingdom among others, were received by President Mukherjee for high tea. Upholding the importance of culinary diplomacy, Bragard said, “Every Indian restaurant abroad is sort of an embassy of the country and Indian food is really coming up in the global arena.” Referring to the club as the “G20 summit of chefs”, he said the association seeks to promote the local cuisines of different nations while keeping the plate healthy.“We believe that the best cuisine in the world is your mother’s cuisine. Since, food is very important and we see diseases coming from bad food, CCC is keen on promoting healthy food,” Bragard said. After their stay in the Capital during which they will explore the famous spice market of ChandniChowk (Khari Baoli), the chefs will visit Agra to see the iconic Taj Mahal, followed by a trip to Jaipur, that will give them an opportunity to experience the local culture and food.Chef Christian Garcia, Chef to Prince Albert II of Monaco, and President of CCC, said that the chefs were looking forward to becoming “ambassadors of Indian gastronomy” after their visit. “It is great for us to discover the wonders of India. It is important for us to share our experience with each other. We will keep the memories of this trip close to our hearts,” Garcia said.Saini, along with four other visiting chefs, will also cook for a charity dinner, the proceeds from which will be donated to the Kailash Satyarthi Children Foundation.
Another month has gone by and a fresh set of books is ready to hit the nearest stands. With an intriguing mix of genres – dominated by non-fiction – August offers simple reading options without the hype that distracts and manipulates readers.There are no big literary names, no grand book launches for the upcoming books in the coming month. Readers, thus, will have an opportunity to pick titles on the basis of merit and not on the credentials of their authors. Also Read – Add new books to your shelfFor those looking to focus on more trending issues, we have a couple of political biographies releasing – and, yes, one is on Uttar Pradesh Chief Minister Adityanath Yogi. More literary readers may look forward to two anthologies of late writer Khushwant Singh. The list also has a revised biography of Agatha Christie, whose thrillers have once again created a buzz on social media after HarperCollins India released 25 limited facsimile editions of the best books from the Queen of Crime. There are several books focussing on economy and business from Hachette India. But here are the five books that we can’t wait to read Also Read – Over 2 hours screen time daily will make your kids impulsivethis August:1. The Generation of Rage in Kashmir by David Devadas (Oxford University Press)This book describes the livid experience of Kashmiris who came of age between 2007 and 2017. It shows that Kashmiris generally had high hopes for peace and stability when the militancy, which began in 1988, seemed to be tapering off around 2006 – but alas, that was not to be. It explores the reasons why there was so much angst and rage, which exploded in agitations and stone-pelting in 2008, 2010, and 2016 and why a new militancy is on the rise. The book also traces the decline of hope among the Kashmiris as the situation worsened from a perceived threat to their identity in 2008 to rage over the killing of innocents in 2010. The anger, the author argues, has finally resulted in support for militancy in 2016. 2. The Greatest Urdu Stories Ever Told by Muhammad Umar Memon (Aleph)Selected and translated by writer, editor and translator par excellence Muhammad Umar Memon, the 25 stories in this book represent the finest short fiction in Urdu literature. Every story in the anthology illustrates one or the other facet of the form in the Urdu literary tradition. But even more than for their formal technique and inventiveness, these stories have been included because of their power and impact on the reader. Despairing, violent, passionate, humorous, ironic and profound – the fiction in “The Greatest Urdu Stories Ever Told” will imprint itself indelibly on your mind.3. Politicshock by Meghnad Desai (Rupa)In this perceptive account, Meghnad Desai, a Labour Peer in the House of Lords, opens up the debate beyond the West and looks at parallels between Prime Minister Narendra Modi and US President Donald Trump as two outsiders who broke through the barriers to reach the top. He analyses Asia’s challenge to Western hegemony and asks if the conventional wisdom about the hegemony of free trade liberalism needs re-examination. He peers into the future to look at the greatest challenge facing the world today: Will the Liberal Order survive, collapse or mutate? Is the world at a cusp? Is history about to resume its course?4. The Epic City: The World on the Streets of Calcutta by Kushanava Choudhury (Bloomsbury) ) A masterful and entirely fresh portrait of great hopes and dashed dreams from a major new literary voice. “Everything that could possibly be wrong with a city was wrong with Calcutta” and yet, after completing his education in the US, Choudhury embodied his parents’ greatest fears by returning to the city they escaped for a better life. Sifting through the chaos and decay for the stories that are ignored by the papers, that don’t fall into any reporter’s beat, “The Epic City” is a soulful, insightful and meticulously researched account of everyday lives and an extraordinary portrait of a city which is a world unto itself.5. India: Priorities for the Future by Bimal Jalan (Penguin).Former Reserve Bank of India Governor Bimal Jalan’s formidable analysis of the last four decades of India’s economic journey illuminates the nation’s transition from a strictly regulated, slow-growth state enterprise to one of the fastest-growing economies in the world. Drawing on this vast experience, he compares two distinct periods – 1980-2000 and 2000-15 – to examine the core changes and their significance, and considers their lessons for the future.ians