Astrophysicist calls on colleagues to develop better models to explain quasars

first_img Measuring the black hole environment of a quasar nucleus 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: Astrophysics: Quasars still defy explanation, Nature 495, 165–167 (14 March 2013) doi:10.1038/495165aAbstractFifty years after finding that these cosmic beacons lie far away, astronomers need to think harder about how they radiate so much energy, says Robert Antonucci. Citation: Astrophysicist calls on colleagues to develop better models to explain quasars (2013, March 14) retrieved 18 August 2019 from https://phys.org/news/2013-03-astrophysicist-colleagues-quasars.html Journal information: Nature Explore furthercenter_img © 2013 Phys.org An X-ray image of the quasar PKS 1127-145, located about 10 billion light-years from Earth. Credit: NASA. (Phys.org) —Robert Antonucci, professor of astrophysics at the University of California, Santa Barbara, suggests in a commentary piece in the journal Nature that he and his colleagues need to develop better models of black-hole systems to help gain more knowledge of quasi-stellar radio sources, known more commonly as quasars. The problem is, he says, after a half century of study, scientists still can’t explain how it is that they emit so much energy. Quasars are highly luminous galactic systems and can be seen from very far away—one was first distance measured only as recently as 50 years ago (it’s anniversary coming March 16 likely inspired Antonucci to provide his commentary piece). And while space scientists generally agree that a quasar is likely a region of space with many elements compacted together, all surrounding a supermassive black hole, not much else is really known about them. Antonucci says that despite all the research that’s been done on them, there are still no good models to describe how they manage to produce so much energy and thus there is no way to predict their behavior. He goes so far as to suggest in comical fashion that the state of science regarding quasars is so limited that researchers should begin hoping an extraterrestrial being will drop by one day to explain it all.In a more serious vein, Antonucci suggests that it’s not an impossible challenge to learn more about quasars, but it will take some effort, and that is the purpose of his article—to push for more research—such as developing stronger computational and computer models and to use new tools such as more sensitive X-ray telescopes to study quasars in better detail.Because they can be seen from so far away, quasars offer researchers a unique opportunity to peek farther back in time than is offered by other celestial bodies. For that reason, it’s important that they be better understood, Antonucci says. Current theories suggest that because they expel jets of energetic particles and emit at radio wavelengths, and because the energy involved is so great, there must be a supermassive black hole at their center. But the details of how it all works is still a mystery and because of that, he says, researchers need to step up their efforts.last_img

Experimental test verifies Heisenbergs measurement uncertainty principle

first_img 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. In the new experiment, two compatible observables, C and D, are jointly measured to approximate two incompatible observables, A and B. The approach can be represented on a sphere. Credit: Ma et al. ©2016 American Physical Society On the other hand, Heisenberg’s original proposal regarding error in the measurement process is not as well understood. In the new paper, a team of researchers led by Professor Jiangfeng Du at the University of Science and Technology of China has reported an experimental test of the measurement aspect of Heisenberg’s uncertainty principle using nuclear-spin qubits.In his original proposal, Heisenberg predicted a tradeoff between error and disturbance. He suggested that when a gamma-ray microscope measures the position of an electron, the measurement inevitably disturbs the electron’s momentum. The smaller the measurement error, the larger the disturbance, and vice versa. This idea was described qualitatively but a complete quantitative description is still lacking today.In the new experiment, the researchers have verified a related tradeoff that builds on a recent proposal. In this tradeoff, measurement inaccuracies are quantified geometrically.”In recent years, the quantification of Heisenberg’s original idea has drawn lots of attention, and a number of experiments have been performed,” Du told Phys.org. “However, the physical validity of some parts of the theory is in dispute. A few years ago, Busch, Lahti, and Werner proposed an innovative approach which is more sensible and persuasive. Our work is based on Busch, Lahti, and Werner’s theory, and makes some improvement. We reformulated their theoretical framework and derived a new tradeoff relation which was verified by our experiment. In this sense, our work tests a fundamental aspect of quantum physics.”In order to verify the new tradeoff, the researchers had to approach the situation somewhat indirectly. According to the measurement uncertainty principle, incompatible observables, such as position and momentum, cannot be measured simultaneously. So instead, the researchers simultaneously measured two compatible observables that are designed to approximate two incompatible observables. Compatible observables can be measured simultaneously, and simulate the measurement device that introduces error and disturbance.As expected, the experimental results verify the tradeoff, showing that the worst-case inaccuracy is determined by the incompatibility of the observables. Overall, the work provides a deeper understanding of Heisenberg’s original idea about the uncertainty principle, and could also have practical applications.”In the future, we may consider the implications for the area of quantum information technology,” Du said. More information: Wenchao Ma et al. “Experimental Test of Heisenberg’s Measurement Uncertainty Relation Based on Statistical Distances.” Physical Review Letters. DOI: 10.1103/PhysRevLett.116.160405, Also at arXiv:1512.07407 [quant-ph] Citation: Experimental test verifies Heisenberg’s measurement uncertainty principle (2016, June 2) retrieved 18 August 2019 from https://phys.org/news/2016-06-experimental-heisenberg-uncertainty-principle.html (Phys.org)—Werner Heisenberg originally proposed the uncertainty principle in 1927, but his original proposal was somewhat different than how it is interpreted today. As a recent paper in Physical Review Letters explains, Heisenberg’s original statement was about error and disturbance in a measurement process. Over the years, however, Heisenberg’s original proposal has been restated in terms of the uncertainties intrinsic to quantum states. This aspect of the uncertainty principle has been studied extensively with well-developed theories and verified experimentally.center_img Journal information: Physical Review Letters © 2016 Phys.org Discovery of uncertainty relations beyond the Heisenberg Explore furtherlast_img

Semiflexible modelbased analysis of cell adhesion to hydrogels

first_img (a) Representation of 2 types of hydrogel constructs evaluated in this study. (b,c) Adhesion of HUVEC cells on collagen and fibrin gels onto top surfaces of 2D hydrogel-coated plates (b) and bulk hydrogel (c), which is measured by CCK-8 assay 2 hrs after seeding. Credit: Scientific Reports, doi: https://doi.org/10.1038/s41598-019-38951-7 Journal information: Scientific Reports Schematic representation of methods for characterizing the physical properties of hydrogel: the bulk stiffness of hydrogel and chain flexibility in viscoelastic networks through the semi-flexible model. Credit: Scientific Reports, doi: https://doi.org/10.1038/s41598-019-38951-7 (a) Representation of 3D bulk hydrogel constructs (b) The inner surface of hollow channels in which the images were captured 24 hrs after seeding. (c) The fraction of cell lining as quantification of cell adhesion. Credit: Scientific Reports, doi: https://doi.org/10.1038/s41598-019-38951-7 More information: Jooyoung Lee et al. Effect of chain flexibility on cell adhesion: Semi-flexible model-based analysis of cell adhesion to hydrogels, Scientific Reports (2019). DOI: 10.1038/s41598-019-38951-7 D. E. Discher. Tissue Cells Feel and Respond to the Stiffness of Their Substrate, Science (2005). DOI: 10.1126/science.1116995 Stéphanie M. C. Bruekers et al. Fibrin-fiber architecture influences cell spreading and differentiation, Cell Adhesion & Migration (2016). DOI: 10.1080/19336918.2016.1151607 Jordan S. Miller et al. Rapid casting of patterned vascular networks for perfusable engineered three-dimensional tissues, Nature Materials (2012). DOI: 10.1038/nmat3357 They introduced a new method of semi-flexible, model-based analysis to confirm that chain flexibility mediated the hydrogel microstructure as a critical factor that allowed cell adhesion at the cell-material interface. The analysis proposed in the study is able to more accurately predict biocompatibility (cytocompatibility) of hydrogels. Results of the work now published in Scientific Reports, provide an important criterion for polymer design and development by enhancing biocompatibility and biofunctionalization at the cell-material interface for biomedical applications in vivo. Hydrogels are made of polymer networks swollen with water and have applications in drug delivery and tissue engineering. Cell-material adhesion is crucial for in vivo biocompatibility and most studies have tested cell behavior by analyzing bulk stiffness of the materials composition. Nevertheless, communication between cells at the hydrogel surface remains to be accurately understood. The FDA approved natural polymers collagen and fibrin, provide excellent biocompatibility for biomedical applications. Also known as semi-flexible polymers, they do not comply with models of flexible chain solutions or rigid-rod networks. The semi-flexible model allows the prediction of chain flexibility of polymer networks by experimentally scaling the elastic plateau modulus. In the experimental setup, the scientists prepared a variety of collagen and fibrin constructs, to test cell adhesion without gravity effects. They controlled hydrogel stiffness using incremental concentrations of each component and quantified the stress-strain relationship based on axial (tensile or compressive) and rotational (shear) stress. To measure the rheological properties of the hydrogels, the scientists used a stress controlled rheometer. They then measured the compressive modulus for tensile testing with a universal testing machine. To investigate surface topography, the scientists used an atomic force microscope, followed by microindentation to measure the Young’s modulus (E) of the hydrogels, where they calculated average (E) using JPK data processing software. Lee and Song et al. believe the study was a first to investigate cell adhesion onto hydrogels using the slope of elasticity of model semi-flexible polymers. , Science Analysis of chain flexibility of hydrogel: (a) power-law scaling of plateau modulus with a concentration of hydrogel for collagen and fibrin. Dash lines are the results of fits to power law equation G’p=cv and microstructure of two representative samples of 0.5% concentration each in collagen and fibrin. (b) cell surface marker, CD31, after cells seeded for 2 hours for two representative samples of collagen and fibrin (0.5% concentration). Credit: Scientific Reports, doi: https://doi.org/10.1038/s41598-019-38951-7 Lee and Song et al. then used 3-D lumen structures of hydrogels to clarify the rate of cell adhesion on collagen and fibrin gels. They observed the cells were better attached to collagen compared to fibrin gels. Cell adhesion phenotypes were also much clearer read more

Dining with the royals

first_imgIt is a state which frequently attracts the jetsetting crowd from all over.  British supermodel Naomi Campbell was there recently to boyfriend and Russian tycoon Vladimir Doronin, Christian Bale and Tom Hardy shot for The Dark Knight Rises at Jodhpur’s Mehrangarh Fort, the now divorced Katie Perry had tied the knot with Russel Brand in Ranthambore…in short, one can go on and on about Rajasthan’s association with the high and mighty. Also Read – ‘Playing Jojo was emotionally exhausting’ But quiz people around the cuisine of the desert state and in most cases, you might come up with a blank look. Rajasthani food is, still by and large, what you eat at the homes of your Rajasthani friends. While Delhi’s food map throws up places near and far, there are only a handful of restaurants which serve Rajasthani food, and apart from that odd thali somewhere, chances are that you might never have heard of them. But if you would really like to know what the royals once ate and what the common folk in Delhi’s neighbouring state (after all, Jaipur is just a few hours’ drive from Delhi) still eat, then we suggest you head to The Imperial. Their latest promotion, aptly called Royal Rajasthan, is all about signature dishes from the state.  So you have your Kair Sangri (as tikkis), the Maas ke Sule, Laal Maas and of course the Gobind Gatte (a more majestic version of the simple gatta). And all this, with a twist and toning down of spices keeping the Capital’s tastes in mind. Also Read – Leslie doing new comedy special with Netflix On the menu are delicacies from Jodhpur, Jaipur, Udaipur and Bikaner, prepared with generous helpings of dry fruits. Among things I tried, and liked, are the Kair Sangri (melt-in-your-mouth delicate and tempered down with raisins), the Maas ke Sule (spicy and tasty), the Gobind Gatte (with ample dry fruits to keep you busy). The Laal Maas was made from very tender lamb and though it looked a fiery red, it wasn’t very spicy and went perfectly well with the Masala Missi Roti.last_img

When cricket went the arty way

first_imgFancy adding a blast of colors to your favorite game? Well, you might not get a chance to play cricket with the specially designed large sized bats displayed at Rajiv Chow metro station, but how about a walk through a display of bats that just got a makeover!Batting for Art…Khelo Front Foot pe organized by Delhi Daredevils and Arts 4 all brought together a selected ensemble of 15 eminent artists from across the country to put a burst of creativity onto some large sized bats. With a thought that art and sports both challenge boundaries, of the body as well as mind, the exhibition presents a riveting tale of art and cricket sharing the same space. It will be a delight for the art connoisseurs in Delhi to witness the merger of two forms that seeks to explore the indomitable spirit of Delhi Daredevils. Also Read – ‘Playing Jojo was emotionally exhausting’The exhibition has bats ranging from the Golden bat of hope colored in golden hues by Neeraj goswami, reflecting the ethos of Delhi Daredevils to Satish Gupta’s Budhha in cricket, upholding the principle of truthfulness in the game. It’s evident in these masterpieces that the 15 different artists, each with a different set of sensibilities have conceived this masterstroke in art. An art that flows in multiple directions dependent on each artists personal experiences and beliefs. Watch out for this play of paint, texture and colour!DETAILWhen:  20 April, 12 pmWhere: Rajiv Chowk Metro stationlast_img

Exhibiting Word Sound Power

first_imgWith the exhibition beginning on 15 January, this will be  the first time that Tate Modern will make its presence felt in India.The show is earmarked as a collateral event of India Art Fair 2014 which has been jointly curated by Khoj’s resident curator Andi-Asmita Rangari and Tate’s Loren Hansi Momudu.Commenting on the exhibition, Director of Khoj Pooja Sood said, ‘We were invited by Tate in 2011 to be part of this collaboration. Different works from the exhibition engage with digital art forms such as sound and the moving image, an area that Khoj has been exploring for some time. This collaboration also points towards an interest shared by both Tate and Khoj in social  issues of migration, political expression and its articulation through voice and silence.’  Tate Modern’s curator Loren Hansi Momudu, said, ‘Word. Sound. Power. was devised to draw a relationship between speech and power and the fact that access to different languages gives access to different power processes. Hence, from a single utterance, to the pronunciation of a name and the declaration of an idea, the voice is a tool through which we assert our presence in the world.’ By bringing together a range of artists working across different creative disciplines,  this exhibition takes a moment to listen to the harmony, and dissonance, of voices rising.Some of the artistes whose works will be on display include Lawrence Abu Hamdan, Caroline Bergvall, Nikolaj Bendix Skyum Larsen and five Indian artists including Amar Kanwar and Mithu Sen.When: From 15 January till 8 February, 11 am to 7 pmWhere: Khoj Studios, S-17, Khirkee Extension, New Delhilast_img

Bowl within the rules Murali urges bowlers

first_imgThe 42-year-old joined the debate whether the process adopted by the International Cricket Council (ICC) in its crackdown on bowlers with suspect actions will diminish the art of spin bowling, a craft which fetched him 800 wickets in Tests and 534 in one-dayers — both records.In July the ICC launched a crackdown on bowlers with suspect actions, suspending Sri Lanka’s Sachitra Senanayake, New Zealand’s Kane Williamson and Pakistan’s high profile bowler Saeed Ajmal. Also Read – Khel Ratna for Deepa and Bajrang, Arjuna for JadejaZimbabwe’s Prosper Utseya and the Bangladeshi duo of Sohag Gazi and Al-Amin Hossan were also reported for suspect actions last month.Apart from paceman Hossain, all other bowlers are off-spinners and some of them bowl the controversial ‘doosra,’ a delivery which turns the other way compared to the normal off-breaks.Under ICC rules — implemented in 2006 after controversy over Muralitharan’s doosra — bowlers are allowed to straighten their arms by 15 degree, established as the point at which any straightening will become visible to the naked eye. But both Ajmal and Senanayake went close to 43 degrees during their assessments in a bio-mechanic lab and need remedial work to get clearance. Also Read – Endeavour is to facilitate smooth transition: ShastriMuralitharan stressed that bowlers should follow the rules. ‘The law was set long time ago,’ Muralitharan told the media. ‘It says 15 degrees (is allowed). If the law has said that any bowler is suspect, umpires can’t call him but they can report him and bowlers have to go for a reviewing test.‘The law was already there when I was playing so you have to go and test and see. If you come under 15 you are legal if you go over that you have to work on your action that is the basic need.last_img

Metro rail authorities conduct drives against station littering

first_imgKolkata: In a unique initiative, Metro Railway Authorities have been conducting cleanliness drives at various stations to check nuisance activities such as spitting, littering like throwing away plastic pouches and other items inside the metro station complex.According to Metro Railways, the drive is being conducted from time to time with an aim to provide clean environment to the commuters.It will not tolerate any nuisance activities such as spitting, littering like throwing of papers, plastic pouches of pan masala, khaini etc. inside the rakes or within the station premises. Also Read – Heavy rain hits traffic, flightsAccording to a press release issued by the Metro railways, during the last two months (i.e. April & May) of this financial year i.e 2018-19, as many as 1,036 cases of nuisance activities have been detected in Metros from which an amount of Rs. 2,66, 250/- have been realized as fine. In this connection, it can be mentioned that during the same period of the previous financial year, 873 cases of nuisance activities were detected from which a penalty of Rs. 2, 22,750/- was realized. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedIn this financial year, the overall amount of money realized as fine has been increased. Commuters are requested to co-operate with the Metro Authorities to keep Stations and premises clean. Those who will be found to be indulging in such activities will face spot fine.Awareness drive would also be conducted so that the people restrain themselves from littering the platform and station premises. According to a senior official of the Metro railways, some people often spit inside the platform as a result of this it becomes difficult to maintain the cleanliness.In a country like India, the major problem is the ignorance of people. Many of the commuters do not understand the littering station or inside the metro rake is strictly prohibited.last_img

4 Bdeshi minors sent back home

first_imgBALURGHAT: Four Bangladeshi minor boys having identified as Mohammad Sah Jamal (17), Rashid Islam (13), Mohammad Sagar Hussein (12) and Iman Islam (14), who were caught around one-and-half-years ago by police from Hili in South Dinajpur and neighbouring Malda respectively have been pushed back to Bangladesh on Wednesday in presence of Aktab Hussein, officer-in-charge posted at Hili Immigration Department for Bangladesh, Shipra Roy, officer-in-charge posted at Hili Immigration Department for India, district coordinator of Child-line, Suraj Das, along with many dignitaries of both countries and police. Also Read – Rain batters Kolkata, cripples normal lifeThe four minor boys were kept in juvenile correctional home, Suvayan in Balurghat, on the basis of the verdict given by the court. Police said the minors hail from Nowga, Dinajpur and Khulna districts in neighbouring Bangladesh. Police interrogation revealed they were forced to sneak through unfenced areas of Hili under the compulsion of extreme poverty.Struggling with poverty in Bangladesh, their parents were forced to send them to India illegally, in search of shelter and jobs here. Perhaps they entered the Indian Territory through the Hili border area with the help of a linkman but without having valid documents, they were nabbed by the police. Accordingly, the court ordered to keep them in juvenile home.Aktab Hussein, officer-in-charge posted at Hili Immigration Department for Bangladesh said: “Initially we had spoken to the BSF high officials posted in Hili International border and Indian government to get the minors back as per appeal of the worried guardians. We are happy that the concerned counterpart responded positively to our appeal.”last_img

Mamata wishes people on Ulta Rath

first_imgKolkata: Chief Minister Mamata Banerjee wished people on the occasion of Ulta Rath Yatra (return journey) on Sunday.Thousands of people joined the ceremony when the chariot returned from Brigade Parade Ground to the temple on Albert Road. In a tweet on Sunday, the Chief Minister said: “Heartiest greetings to all on the occasion of Ulta Rath Yatra”.It may be mentioned that Chief Minister Mamata Banerjee had inaugurated the Rath Yatra festival organised by ISKCON on July 14. She had pulled the rope and marked the beginning of the festival. She had said: “Religion is personal but people from every faith take part in the festival of peace and harmony.” Also Read – Rain batters Kolkata, cripples normal lifeThe chariot of ISKCON has stayed at Brigade Parade Ground since July 14, where thousands of people visited to offer prayers to Lord Jagannath, Balaram and Subhadra. There was a fair at the grounds on the eve of Rath Yatra. Various cultural programmes were also organised in the past seven days.On Sunday, the festival of Ulta Rath Yatra (return journey) took place. The chariot was brought back to the temple through Outram Road near Park Street Metro, Jawaharlal Nehru Road, Dorina Crossing, S N Banerjee Road, Moulali Crossing, CIT Road, Suhrawardy Avenue, Park Circus Seven Point Crossing, Shakespeare Sarani and Hungerford Street. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedThe police made an elaborate arrangement to ensure that no untoward incident takes place during the festival and equal stress was given on traffic management.”There was not as much pressure on Sunday as weekdays. But there was necessary arrangement in place to ensure that no one faces any inconvenience,” said a police officer.The festival of Ulta Rath has also taken place in many parts of the state. Thousands of people have joined the festival at Mahesh in Hooghly.last_img