For a long time, scientists have assumed that the very first stars were powered by fusion, in processes similar to what goes on in present day stars. But a new theory is emerging to challenge that view. “The first stars were different in a lot of ways,” Katherine Freese, a theoretical physicist at the University of Michigan, tells PhysOrg.com. 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: First stars might have been powered by dark matter (2008, February 12) retrieved 18 August 2019 from https://phys.org/news/2008-02-stars-powered-dark.html Stars Fueled by Dark Matter Could Hold Secrets to the Universe Explore further Freese, along with Douglas Spolyar at the Unversity of California, Santa Cruz and Paolo Gondolo at the University of Utah in Salt Lake City, posit that dark matter annihilation was the source of energy that powered the earliest stars, formed about the time the universe was between 100 and 200 million years old. If they are right, some of what we know about stellar formation – and the formation of the universe itself – could be called into question. Their work appears in Physical Review Letters with the title “Dark Matter and the First Stars: A New Phase of Stellar Evolution.”“Annihilation means that matter goes into something else,” Freese explains. She says that everything has a partner opposite – matter and anti-matter, electrons and positrons. When these opposites meet, their identity is lost and the energy goes elsewhere. “Dark matter particles are their own anti. When they meet, one-third of the energy goes into neutrinos, which escape, one-third goes into photons and the last third goes into electrons and positrons.” “In order for a star to form, in order for its matter to collapse into a dense object, it has to be able to cool off,” Freese continues. “We noticed that in the first stars something was competing with the cooling. The stars couldn’t collapse down small enough to get fusion going. But they were still giving off energy. They were in a phase we hadn’t discovered before.” Freese describes how the first stars likely moved from the dark matter phase and into the fusion phase. “The annihilation products getting stuck is what allows the dark matter heating to stay inside the star, and is what prevents the star from collapsing into a fusion driven one.” When all the dark matter is gone, Freese says, the star can collapse enough for fusion to take over inside the star. Hydrogen and helium atoms are forced together by this process to form new elements (carbon, nitrogen, oxygen and metals) until it becomes dense enough to collapse in on itself. Finally, the star goes supernova, spewing the new elements created in its core across the universe to be used in the formation of later stars.“This new phase is only true in the first stars,” Freese insists. “The stars we see today are called population one stars. Earlier stars were population two stars. The first stars are referred to as population three stars. Our work is to modify how we believe population three stars developed. At first, they weren’t fusion driven.”If Freese and her colleagues are right, it could change what we know about how stars are formed. “It adds a new phase of stellar evolution,” Freese says. She says that studying this theory will have to wait until 2013, when NASA is scheduled to launch the James Webb Telescope. “We call them dark stars,” Freese explains, “but they would still shine, looking a little different. They would be cooler than a fusion driven star. We hope the next phase telescope will be able to tell between the standard stars now, and what we think happened in the first stars.”Until then, Freese and her peers will continue to speculate on the properties of the first stars, and try to figure out how the new phase in stellar evolution might have affected the timing of other developments in the universe. “It really gets into speculation here,” she says, “but this could affect the timing of the fist black holes, and the development of our own galaxy.”Copyright 2007 PhysOrg.com. 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.
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. More information: www.stanford.edu/~hspwong/via TechnologyReview Scientists ‘clone’ carbon nanotubes to unlock their potential Explore further © 2013 Phys.org
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 More information: Origin of Anomalous Water Permeation through Graphene Oxide Membrane, Nano Lett., 2013, 13 (8), pp 3930–3935. DOI: 10.1021/nl4020292AbstractWater inside the low-dimensional carbon structures has been considered seriously owing to fundamental interest in its flow and structures as well as its practical impact. Recently, the anomalous perfect penetration of water through graphene oxide membrane was demonstrated although the membrane was impenetrable for other liquids and even gases. The unusual auxetic behavior of graphene oxide in the presence of water was also reported. Here, on the basis of first-principles calculations, we establish atomistic models for hybrid systems composed of water and graphene oxides revealing the anomalous water behavior inside the stacked graphene oxides. We show that formation of hexagonal ice bilayer in between the flakes as well as melting transition of ice at the edges of flakes are crucial to realize the perfect water permeation across the whole stacked structures. The distance between adjacent layers that can be controlled either by oxygen reduction process or pressure is shown to determine the water flow thus highlighting a unique water dynamics in randomly connected two-dimensional spaces.via Nanotechweb Journal information: Nano Letters © 2013 Phys.org The new type of ice was discovered via atomistic modeling which allowed the researchers to control its development. The new type of ice, a form of bilayer ice, can only form under very special conditions. In this new effort, the researchers were experimenting with graphene oxide films, which are unique because they allow water, but no other liquids or gasses, to pass through.In their model, graphene oxide layers were stacked one on top of one other and then water was allowed to pass through one of the membranes where it was chilled to below freezing at the junction point. The water between froze into a lattice pattern very similar to the membrane. To create the bilayer ice, more water was allowed to pass through the membrane, freezing on top of the first layer. Rather than adhering to one another as would occur with normal ice, the two layers of ice actually slide against one another, in a zig-zag fashion as they follow the lattice pattern. This is because, the researchers explain, the water makes its way through the membrane in a special way—one that allows for the water to freeze into a new kind of ice crystal shape.The researchers note that normally when (reduced) graphene oxide is layered, the distance between the two pieces is just 0.6 nm—enough for just one layer of water to freeze into ice. To allow for two layers, the researchers used unreduced graphene oxide which allowed for a span of 0.9 nm—enough extra space to allow for a second layer of ice to form.The newly found properties of graphene oxide and ice formation could lead to new types of filters or membranes that are capable of separating different substances. Also, if the graphene oxide were doped with nitrogen, the researchers note, the possibility exists for creating a new type of catalyst. (Phys.org) —A combined team of researchers from Korea and The Netherlands has discovered a new type of ice that forms between layers of graphene oxide. In their paper published in the journal Nano Letters, the team describes the ice’s properties and how they caused the ice to form. Citation: Researchers observe new type of ice forms between layers of graphene oxide (2013, August 14) retrieved 18 August 2019 from https://phys.org/news/2013-08-ice-layers-graphene-oxide.html New findings on the structure of graphite oxides in alcohols
(Phys.org)—A pair of researchers looking into whether Massive Open Online Courses (MOOCs) are helping to bridge the disparity gap in education access in the U.S. has found that those who take the courses tend to be from wealthier neighborhoods. In their paper published in the journal Science, John Hansen, with Harvard University and Justin Reich, with MIT describe their research efforts and why they came to believe that MOOCs are not the remedy to educational disparity that many had hoped. 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. Two stylized representations of the possible effects of a technological innovation on educational outcomes for students from high- and low-socioeconomic backgrounds are shown. This material relates to a paper that appeared in the Dec. 4, 2015, issue of Science, published by AAAS. The paper, by J.D. Hansen at Harvard University in Cambridge, MA, and colleagues was titled, “Democratizing education? Examining access and usage patterns in massive open online courses.” Credit: John Hansen and Justin Reich More information: J. D. Hansen et al. Democratizing education? Examining access and usage patterns in massive open online courses, Science (2015). DOI: 10.1126/science.aab3782AbstractMassive open online courses (MOOCs) are often characterized as remedies to educational disparities related to social class. Using data from 68 MOOCs offered by Harvard and MIT between 2012 and 2014, we found that course participants from the United States tended to live in more-affluent and better-educated neighborhoods than the average U.S. resident. Among those who did register for courses, students with greater socioeconomic resources were more likely to earn a certificate. Furthermore, these differences in MOOC access and completion were larger for adolescents and young adults, the traditional ages where people find on-ramps into science, technology, engineering, and mathematics (STEM) coursework and careers. Our findings raise concerns that MOOCs and similar approaches to online learning can exacerbate rather than reduce disparities in educational outcomes related to socioeconomic status. The study suggests that there are obstacles that prevent students from less wealthy neighborhoods from accessing free online education and presumably the better economic opportunities that would follow were those obstacles to be removed. Citation: Study shows Massive Open Online Courses used mostly by wealthier people (2015, December 4) retrieved 18 August 2019 from https://phys.org/news/2015-12-massive-online-courses-wealthier-people.html Neighborhood income for US Harvard/MIT MOOC participants compared to general US population. This material relates to a paper that appeared in the Dec. 4, 2015, issue of Science, published by AAAS. The paper, by J.D. Hansen at Harvard University in Cambridge, MA, and colleagues was titled, “Democratizing education? Examining access and usage patterns in massive open online courses.” Credit: John Hansen and Justin Reich © 2015 Phys.org Massive open online courses haven’t lived up to the hopes and the hype, professors say Access to a high quality education is not guaranteed in the U.S. People who live in poorer neighborhoods tend to live in less well funded schools with lower success rates. Over the years some have espoused technological advances as the key to leveling the playing field—some believed radio could change things by offering educational programming, others believed television would help, offering even more programming such as that provided by PBS. Unfortunately, such hopes have not been realized as the disparity gap in education has only grown wider between people living in rich neighborhoods versus those living in poor neighborhoods. More recently, some have suggested that the Internet might finally provide the path to change—universities such as Harvard and MIT began offering free courses online, which over time have come to be known as MOOCs. But now, Hansen and Reich have found that the majority of young people taking advantage of such coursework are kids living in wealthy neighborhoods, suggesting that instead of shrinking the disparity gap, they are actually making it wider.To come to these conclusions, the research pair obtained data on 68 students enrolled in MOOCs offered by Harvard and MIT covering the years 2012 to 2014, which included student addresses. Those addresses when compared with census data allowed the researchers to identify the average wealth and education level of adults in the neighborhoods where the students lived. The researchers looked at both registration and completion rates of the student enrollees, and found that the people using MOOCs to further their education were primarily from wealthier neighborhoods, thus it was no surprise that most of those that completed the courses and received a certificate, were also from those same wealthy neighborhoods. Journal information: Science Explore further
Journal information: Science Advances More information: François Balfourier et al. Worldwide phylogeography and history of wheat genetic diversity, Science Advances (2019). DOI: 10.1126/sciadv.aav0536 Citation: Researchers trace the genetic history and diversity of wheat (2019, May 30) retrieved 18 August 2019 from https://phys.org/news/2019-05-genetic-history-diversity-wheat.html Explore further
Even as World Heritage is being celebrated today and Indian cinema will complete its journey of 100 years on 3 May this year, there is an unfortunate loss of invaluable cinematic heritage, including the first silent film as well as the first talkie.Cinema was introduced to India, as soon as it came about in the world, thanks to the Lumiere brothers from France who screened a series of silent shorts Arrival of a Train, Leaving the Factory etc at the Watson Hotel in Bombay (now Mumbai) on 7 July, 1896. Also Read – ‘Playing Jojo was emotionally exhausting’Once the toast of town, the hotel now known as Esplanade Mansions, and India’s oldest cast-iron building, is currently in shambles, its old sepia-toned images providing some consolation to heritage lovers.While Watson may still be standing, Coronation Theatre where India’s first silent feature film Raja Harishchandra on 3 May in 1913 and Majestic Cinema where it’s first talkie Alam Ara on 14 March, 1931, were screened, have met with much worse fate and have disappeared. Also Read – Leslie doing new comedy special with Netflix‘I must say Coronation and Majestic were India’s history and should have been preserved as heritage for posterity but the love for cinema has been replaced today with pure business. And we anyway do not have a culture of archiving or preservation in our country,’ says P K Nair, founder and ex-director, NFAI.Nair’s life has been captured in a brilliant documentary Celluloid Man which talks about his marathon efforts in single-handedly building, one of the most enviable film archives in India. Shivendra Singh Dungarpur, who produced and directed this landmark film which releases in theatres on May 3 to coincide with the centenary, has said that over 1700 silent films were made in India of which only 9 or so have survived in the National Film Archives of India, thanks to Nair’s efforts.Nair, who retired from NFAI in 1991, by then had created a massive treasure trove of films and documentaries in black and white and in colour but after his retirement his carefully collected celluloid films and documentaries weren’t kept in the right conditions as needed, Dungarpur’s film points out.However, amidst all the pain of losing our historic treasure, it is Nair’s efforts only that bring some cheers amidst the gloomy scene on the cinematic heritage front.By 1991, NFAI had 12,000 films in its collection, out of which 9000 were in Indian languages, the majority being black and white. Included in the Indian category were films made by foreign studios in India or by Europeans living in India.The archive has rare silent films like Jamai Babu, Ashok Kumar and Devika Rani-starrer Achhut Kanya (1936), V Shantaram’s Duniya Na Mane (1937), second oldest Malayalam film Marthanda Varma’ (1933), and also opening fanfares and cards of production companies like Imperial Movietone, Wadia Movietone, Bombay Talkies, AVM Studios and Prabhat Studios, among other rarities.‘We also had some fine documentaries produced by Burmah Shell on various parts of India, but I don’t know what their current status is now,’ the 80-year-old.He also tells the story of the tragedy of Alam Ara and even some of its few reels left were lost forever as he says ‘filmmakers never cared for what they created’.
Increasingly school students, are using their spare time to go beyond academics into areas like social work, to lend a helping hand to those less privileged.‘Don’t do good work to see results in your lifetime. Do it so that others get motivated. It may be just a drop in the ocean but even that makes a difference’, says Anushka Mandal, a class 11 student, from Kolkata who played Secret Santa to the underprivileged during one Christmas.Anushka, student of a Kolkata school, says she helped 500 people who were living on the streets by distributing blankets to them during winters in 2012. Also Read – ‘Playing Jojo was emotionally exhausting’She claims to have raised a total of Rs 55,000 from friends and family to buy blankets. Organising volunteers into five teams Mandal says she went around the city on one cold, winter night and laid blankets on people sleeping on the pavements.‘During winters, there were stories of people dying. I really wanted to do something for them. My mother, who has been in social work since her school days, told me to go to some key companies and some friends and ask them to donate. On December 27, I asked some people to come with me. We went in different directions of the city and laid blankets on the poor, sleeping on streets. It felt good,’ says Anushka. Also Read – Leslie doing new comedy special with NetflixAnushka says she moved by what she saw at a Chennai hospital when she was a ten years old and has continued to be motivated by that incident ever since.‘I was diagnosed a diabetic when I was eight years old. I was really young and no specialised doctors were available in Kolkata then. We then decided to go to a hospital in Chennai.There I saw the doctors giving medicines and injections to diabetic children, who could not afford it. That motivated me to help the needy,’ says Anushka. Anushka was among other school children who went to Washington recently to represent the country at the Pramerica Spirit of Community Awards.Maneka, a class 12 student from Gurgaon aspires to become a social entrepreneur and deal with social issues.‘I taught English in slum areas near my house. There I met a girl named Pooja, who told me how her family received only three litres of water a day. I thought of writing about her story and about the benefits of conserving water,’ says Maneka.The school girl, who says she aims to become a social entrepreneur says she self-published her book titled Rohan On A Water Saving Spree. Written in a narrative style the illustrated book targets children aged 5 to 11 and shares important and practical tips to save water within their homes.While Maneka works towards conserving water, city-based boy Aakash Pawar strives hard to combat social evils like child marriage and child labour. A class eleven student Aakash Pawar has been teaching underprivileged children and conducting development programs for them for the past seven years.‘In class four, I used to play with some underprivileged children near my house. Gradually I started noticing that out of them three girls were not sent to school and assigned household chores, while the boys went to school. When I was in class 6, I started persuading people to send their daughters to school,’ says Aakash.Today with 20 members, his organisation, which receives funding from other NGOs and individuals uses simple, yet innovative methods to teach the children.‘I make them play puzzles. Spell out different words together and use simple games like Name, Place, Animal and Thing to teach the children,’ says Aakash ‘We have two hands. One is for us, while the other is to help the needy. Today, people are using their hand for their own prosperity but we should use both and make a difference to the society,” says Aakash.PTI
High levels of emotional exhaustion that come from workplace anxiety can directly lead to lower job performance, says a study.The effect of workplace anxiety on job performance is closely connected to the quality of relationships between employees, their bosses and their co-workers, said researchers from the University of Toronto-Scarborough.They found that anxiety can lead to lower job performance. “Workplace anxiety is a serious concern not only for employee health and
A movie is something which can make or break conceptions of people as it is the most accessible medium through which people are exposed to various unfound and unheard happenings, in the best way possible. In order to reach out to the movie lovers and to celebrate the largest evacuation in the history of civil aviation, Air India, Kolkata, took the initiative to arrange a special screening of Airlift at the prestigious Inox auditorium at Forum Mall in Kolkata, recently. Also Read – ‘Playing Jojo was emotionally exhausting’The employees took pride in soaking in the patriotic movie along with corporate clients, travel agents and distinguished guests. An FM contest was also initiated earlier on Air India, the winners of which were given free tickets for the movie. Air India had scripted one of the most heroic saga of evacuation in recent times when it airlifted Indians stranded at Kuwait and Iraq in the early nineties.This ‘Operation Airlift’- an epic act, spanning over 59 days, rescued over 1,70,000 passengers through 88 flights operated by Air India. The same has been immortalised in the superhit movie Airlift which has received accolades from the public. Also Read – Leslie doing new comedy special with NetflixThis operation also saw the use of Airbus A320 aircraft, A300 B4, 273-seater A300 B2 aircraft along with boeing aircrafts with large seating capacities to fly out passengers.The national airlines rose to the occasion to meet the stiff challenge of evacuation from a strife-torn country. When the first phase of operation ended on October 12, 1990, it was a triumph for all sections of employees of the airline who spared no effort in fulfilling the task risking their life for the cause of the nation. And, this legacy of bravery continues, when Air India spread its wings to operate special flights to Djerba, in Tunisia, to evacuate more than 1,200 stranded Indians from Libya and Malta. The relief flights were operated to bring home Indian expatriates stranded in strife-torn countries. National carrier Air India has been spreading its wings to connect every corner and heart of India even as it has been serving as the country’s flying ambassador to the world at large. It pioneered aviation in India and its history is synonymous with the history of civil aviation in the country. Air India is not just an airline that transports passengers, baggage and cargo. Air India has always been identified with India from standing by the nation, during any crisis, reflecting the tradition and culture of the country, or showcasing the strength of emerging India. Ever since its inception, it has been extending its unstinted support to encourage and uphold our traditional arts and culture besides serving as the nation’s second line of defence. Indeed, Air India has been inextricably woven into the tapestry of our country’s tradition – to power the nation forward in its relentless pursuit of excellence.
Kolkata: State Education Partha Chatterjee made it clear that the educational institutes in the state will not observe September 29 as “Surgical Strikes Day”.Slamming the BJP-led government at the Centre, he said that “Surgical Strikes Day” is the saffron party’s agenda and an attempt to “malign and politicise” the Army.”This is an agenda of the BJP and it is trying to push this agenda by using the UGC ahead of elections. It is a matter of shame that they are using the UGC for their political agenda,” Chatterjee said. Also Read – Rain batters Kolkata, cripples normal lifeIt may be mentioned that the minister’s reaction came in the wake of the University Grants Commission (UGC) telling the higher education institutions earlier this week, to hold programmes and activities to celebrate “Surgical Strikes Day”.According to Chatterjee, the Indian Army should always be kept above politics and controversies.”We have full respect for our soldiers and their sacrifices. BJP should learn how to be respectful to the sacrifices of our soldiers. They should have asked us to observe the day in the name of the sacrifices made by our soldiers,” he added. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedIn a letter to Vice-Chancellors of different universities on Wednesday, the UGC suggested that institutions ask students to “pledge their support” to the armed forces through letters and cards, which the government will use for publicity.Talk sessions by ex-servicemen about sacrifices made by the armed forces, special parades by NCC and visit to exhibitions are among the prescribed events by the UGC for the celebration.A surgical strike is a military attack which results in, was intended to result in, or is claimed to have resulted in damage to only the intended legitimate military target and no or minimal collateral damage to surrounding structures, vehicles, buildings, or the general public infrastructure and utilities.On September 29, 2016, eleven days after the Uri attack, the Indian Army conducted “surgical strikes” against suspected militants in Pakistani-administered Kashmir. However, Pakistan denied such allegations.