“Most conventional atomic clocks need a more conventional, non-atomic clock, like a quartz crystal, to keep them ticking,” William Happer tells PhysOrg.com. “We’ve developed a system that would be self-ticking, using a specific laser.” Redefining the limits of measurement accuracy 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. “It’s really a souped-up mode-locked laser,” Happer says. “While our laser has much in common with a mode-locked laser, there are some differences. The atoms in the vapor cell notice if the frequency of the mode-locked laser drifts and they automatically correct the frequency with no need for any external feedback loops.”Happer continues: “An important benefit of push-pull pumping with alternating circular polarization is that none of the atoms are wasted.” “In most atomic clocks,” Jau adds, “many of the atoms are wasted. Only a very few are in the clock state. With this push-pull pumping, all of the atoms are put into a clock state.”Along the way, the two discovered something interesting. “The self-modulation occurs over a limited range of laser injection current. We weren’t surprised that too little current didn’t work. What surprised us was that too much current caused the laser to stop modulating,” Happer says. Jau continues: “This new oscillator, where the polarized atoms, the modulated photons, and the laser gain centers are all coupled together has very rich and interesting physics. ”Happer does point out that these oscillators could not replace the extremely precise, but large atomic clocks that occupy whole rooms. “It’s really to improve the workings of small, portable atomic clocks,” he emphasizes. “It eliminates the need for quartz crystals or photodetectors. Hopefully, with fewer parts, it will be less expensive to manufacture, and more stable.”Jau agrees: “This is a primitive idea, how to make an atomic clock by using pure optical methods without a quartz crystal. But it works better with reduced components and power consumption.”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 This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Citation: Self-ticking oscillator could be next for portable atomic clocks (2007, December 10) retrieved 18 August 2019 from https://phys.org/news/2007-12-self-ticking-oscillator-portable-atomic-clocks.html Happer is a scientist at Princeton University. He, along with his young colleague Yuan-Yu Jau, invented a push-pull laser-atomic oscillator that can be useful in a variety of applications, including questions of fundamental physics, use in portable atomic clocks and coherent optical combs. “We didn’t start out thinking about applications, really,” Happer says. “We’re physicists. We just wanted to see if we could make this type of oscillator work.” The results of Happer and Jau’s work can be found in Physical Review Letters: “Push-Pull Laser-Atomic Oscillator.”Jau explains that even though they didn’t set out to build a better portable atomic clock, he thinks that they have succeeded. “We believe this is the first demonstration of making an oscillator that produces an atomic-clock signal in both electrical and optical forms by purely optical means,” he says. “This is simple. There are fewer components and lower power consumption.”“The new clock needs neither a quartz crystal with its electronics nor a photodetector,” Happer adds.Jau and Happer explain that in conventional atomic clocks, a quartz crystal is used “as a flywheel to keep the clock ticking strongly, with the atoms as a weak controlling element.” They point out that if the quartz crystal fails, the clock will cease working. “These are the types of clocks used in GPS satellites and in cell-phone towers,” Happer says.Jau points out that better precision is becoming increasingly necessary: “Mini atomic clocks can be helpful. There are many systems now working faster and faster, and transmitting large quantities of data, especially in high-speed communications. A laser atomic clock like this would be less complicated than the conventional kind, with comparable precision.”The push-pull laser-atomic oscillator built by the two consists of a semiconductor laser with alkali-metal vapor (in this case Potassium) in the external cavity. A time independent current is used to pump the semiconductor laser. “The laser will automatically modulate its light and its electrical impedance at the clock frequency of the atoms,” Happer says. This in turn eliminates the need for an external modulator, like the quartz crystal, or for a photodetector. Explore further
TED SpaceTop presenter is redefining hands-on computing (w/ video) Citation: MIT group’s shape display steps to new realm in interaction future (w/ Video) (2013, November 14) retrieved 18 August 2019 from https://phys.org/news/2013-11-mit-group-realm-interaction-future.html Their paper, “inFORM: Dynamic Physical Affordances and Constraints through Shape and Object Actuation,” by Sean Follmer, Daniel Leithinger, Alex Olwal, Akimitsu Hogge and Hiroshi Ishii of the MIT Media Lab, explains the system in detail. They wrote that the system is a shape display that enables “dynamic affordances, constraints and actuation of passive objects. Shape displays allow for more general purpose shape change than many other actuated or shapechanging interfaces, and thus are ideal research platforms.”Shape displays still remain limited in scale and cost, they said, but “this work is an exploration of the interaction capabilities and is meant to inspire further research in this area. Our belief is that shape-changing interfaces will become increasingly available in the future, and this work tries to push towards creating a vocabulary and design space for more general-purpose interaction for shape displays, including rendering of both content and UI elements.”A key comment that indicates the role of inFORM within their overall research efforts is what they say on their inFORM web page: “InFORM is a step toward our vision of Radical Atoms.”The Tangible Media Group explain how they view graphical user interfaces, tangible user interfaces, and Radical Atoms: “A graphical user interface only lets us see information and interact with it indirectly, as if we were looking through the surface of the water to interact with the forms below.” A tangible user interface, meanwhile, is “like an iceberg: there is a portion of the digital that emerges beyond the surface of the water—into the physical realm—so that we may interact directly with it.” Radical Atoms describes the group’s “vision for the future of interaction, in which all digital information has physical manifestation so that we can interact directly with it—as if the iceberg had risen from the depths to reveal its sunken mass.” (Phys.org) —The Tangible Media Group at MIT Media Lab have been working on a shape-shifting surface called inFORM where, as their video indicates, users interact with digital matter in interesting ways that go far beyond boxed-in interactions with a traditional computer. Outside MIT, observers have described their system not only as a shape display but as a shape-shifting surface; The team at MIT that is behind inFORM explain it as a “Dynamic Shape Display that can render 3D content physically, so users can interact with digital information in a tangible way. inFORM can also interact with the physical world around it, for example moving objects on the table’s surface. Remote participants in a video conference can be displayed physically, allowing for a strong sense of presence and the ability to interact physically at a distance.” Explore further More information: tangible.media.mit.edu/project/inform/tangible.media.mit.edu/vision/ © 2013 Phys.org They are now exploring application areas for the inFORM shape display. How could it be used in real-life scenarios? The team sees one potential in geospatial data, such as maps, GIS, terrain models and architectural models. “Urban planners and architects can view 3-D designs physically and better understand, share and discuss their designs.” They would also like to explore surgical simulations. 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.
Journal information: Proceedings of the National Academy of Sciences (Phys.org)—A team of researchers with members from Mexico, the U.S. and Germany has found that the demise of the pre-Columbian Mesoamerican society centered around a city known as Cantona, was likely due to a combination of weather and politics. In their paper published in Proceedings of the National Academy of Sciences, the team describes their study where they compared lake sediments with archeological evidence to provide a clearer picture of life in the area back when the city was still active and what factors led to both its rise and fall. © 2015 Phys.org More information: Cultural implications of late Holocene climate change in the Cuenca Oriental, Mexico, Tripti Bhattacharya, PNAS, DOI: 10.1073/pnas.1405653112AbstractThere is currently no consensus on the importance of climate change in Mesoamerican prehistory. Some invoke drought as a causal factor in major cultural transitions, including the abandonment of many sites at 900 CE, while others conclude that cultural factors were more important. This lack of agreement reflects the fact that the history of climate change in many regions of Mesoamerica is poorly understood. We present paleolimnological evidence suggesting that climate change was important in the abandonment of Cantona between 900 CE and 1050 CE. At its peak, Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants. The site is located in the Cuenca Oriental, a semiarid basin east of Mexico City. We developed a subcentennial reconstruction of regional climate from a nearby maar lake, Aljojuca. The modern climatology of the region suggests that sediments record changes in summer monsoonal precipitation. Elemental geochemistry (X-ray fluorescence) and δ18O from authigenic calcite indicate a centennial-scale arid interval between 500 CE and 1150 CE, overlaid on a long-term drying trend. Comparison of this record to Cantona’s chronology suggests that both the city’s peak population and its abandonment occurred during this arid period. The human response to climate change most likely resulted from the interplay of environmental and political factors. During earlier periods of Cantona’s history, increasing aridity and political unrest may have actually increased the city’s importance. However, by 1050 CE, this extended arid period, possibly combined with regional political change, contributed to the city’s abandonment.Press release Explore further Intensive agriculture may have exacerbated drought in ancient Maya city Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants at its peak. Scientists believe climate change was part of the reason the city was eventually abandoned. The researchers note that little work has been done to gain an accurate portrayal of what the climate was like in Mesoamerica during the times when various early people lived there, creating civilizations that in many cases vanished leaving behind ruins for modern scientists to ponder. In the case of Cantona, a city whose remains now lie east of modern Mexico City, the assumption by many has been, as it has for other long gone societies in central and South America, that it died due to drought. In this new study, the researchers assumed there was likely more to the story and so sought to find out more about weather conditions during that time.They started by collecting and studying sediments in nearby Aljojuca lake, which provided an accurate picture of drought conditions, before, during and after the time of the people in the area, which is now known as Cuenca Oriental.Prior research has shown that Cantona was occupied from approximately 600 BCE to 1050 CE and that its population grew steadily over the course of its first six hundred years, then grew faster from 50 and 600 CE—but the team notes, the lake sediment suggests that during that time period, the area had entered a drying trend. More interesting perhaps, they found that the population in the city grew even faster from 600 – 900 CE, despite increasing aridity. After that, things changed, though it is not clear exactly why, the population dropped over the following century and a half and then the people disappeared altogether. The team notes that later development in the city showed increased fortifications, which could have either been to repel invading armies or to fend off migrants seeking refuge from a drier environment that left them with little ability to farm on their own. That would explain, the team notes, the continued increase in population during the initial phase of the drought trend. Locations of Cantona (red square) and other major sites in central highland Mexico (black circles), along with location of Aljojuca maar. Topography from 1,500 m above sea level (masl) to 4,500 masl, contoured by 500 m. Gray line shows outline of the Cuenca Oriental. (Inset) Map shows Google Earth satellite imagery of region around Cantona, with outline of the city shown in gray. Labels designate the southern, central, and northern architectural clusters within the city. Credit: Tripti Bhattacharya, PNAS, doi: 10.1073/pnas.1405653112 Citation: Climatic history study suggests pre-Columbian Mesoamerican society’s demise was more complex than just weather (2015, January 27) retrieved 18 August 2019 from https://phys.org/news/2015-01-climatic-history-pre-columbian-mesoamerican-society.html 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.
© 2015 Phys.org When big ships unload their cargo, they are left mostly empty, which creates a weight distribution problem—to fix that problem, giant pumps are used to fill ballast tanks with water from the sea in which they reside. Unfortunately, those pumps also suck up local organisms, which then live in the ballast tanks for some period of time as the ship travels to a place to pick up cargo. Upon arrival, the water in the ballast tanks is pumped back into the sea in anticipation of new added cargo. But, as scientists, environmentalists, sports enthusiasts and others have found, that ballast water may contain an organism that is able to take up residence (dubbed an invasive species) in its new part of the world, and sometimes is able to dominate those already there, putting the legacy residents at risk. In this new effort, the researchers sought to put some metrics on the ballast tank dumping problem around the shores of their native Australia in an attempt to better understand the invasive species risk for the country. They gathered historical shipping data for the period 1999 to 2012, which included ballast filling and dumping information and data regarding organisms that are known to be able to survive living in ballast tanks.In analyzing their data using a computer model, they found that ballast dumping in Australian seaports more than doubled during the study period and that the majority of the increase was related to mining and forestry operations, which meant that the dumping increase was more often located in remote ports near mines, rather than in more established areas. They also found that a large percentage of ballast water was coming from the waters around Southeast Asia and China, which they suggest offers an opportunity for more research regarding which species from those areas might be in the ballast water being dumped in Australian ports and other places around the world. Explore further (Phys.org)—A small team of math and biological researchers with the University of Adelaide, has found that the amount of ballast water being dumped into the waters around Australia more than doubled over a thirteen year study period increasing the possibly of invasive species introduction. In their paper published in Royal Society Open Science, the team describes how they studied historic ballast data to create a model of ballast dumping, and discovered that most of the increase can be attributed to mining operations. More information: Temporal modelling of ballast water discharge and ship-mediated invasion risk to Australia, DOI: 10.1098/rsos.150039 AbstractBiological invasions have the potential to cause extensive ecological and economic damage. Maritime trade facilitates biological invasions by transferring species in ballast water, and on ships’ hulls. With volumes of maritime trade increasing globally, efforts to prevent these biological invasions are of significant importance. Both the International Maritime Organization and the Australian government have developed policy seeking to reduce the risk of these invasions. In this study, we constructed models for the transfer of ballast water into Australian waters, based on historic ballast survey data. We used these models to hindcast ballast water discharge over all vessels that arrived in Australian waters between 1999 and 2012. We used models for propagule survival to compare the risk of ballast-mediated propagule transport between ecoregions. We found that total annual ballast discharge volume into Australia more than doubled over the study period, with the vast majority of ballast water discharge and propagule pressure associated with bulk carrier traffic. As such, the ecoregions suffering the greatest risk are those associated with the export of mining commodities. As global marine trade continues to increase, effective monitoring and biosecurity policy will remain necessary to combat the risk of future marine invasion events. New requirements for ballast water dumped by ships 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: Ship ballast dumps around Australia climbing increasing risk of invasive species getting foothold (2015, April 22) retrieved 18 August 2019 from https://phys.org/news/2015-04-ship-ballast-dumps-australia-climbing.html Journal information: Royal Society Open Science
They claim to be interested in quantum physics but are one of the upcoming metal bands in the city. Intrigued? We are too. Here’s talking to Heisenberg on what makes them tick, physics or music, or both.Where does the name of your band come from?Heisenberg was a renowned physicist. The members of our band have been fascinated with quantum physics and the name goes off pretty well when you are writing songs which deal with waves, consciousness and uncertainty in life. Also Read – ‘Playing Jojo was emotionally exhausting’How did you start off?We were playing for various bands, sessioning for some, sharing our members and generally doing covers at college fests. Soon we realised the limitations of being another cover band. So we hit the studio in 2010 to record our first song, Thickskinned, which was a very rough recording with midi bass track and very weird programmed drums — but it helped us strengthen our profile and allowed us to participate in a lot of great college fests. Also Read – Leslie doing new comedy special with NetflixWhat is your original brand of music? Do you guys have a signature sound?We haven’t found our signature sound yet but we are a heavy metal band with a lot of influences from jazz, Indian classical as well as groove metal groups. How has it been thus far?We have been around for two years now. Though there were no issues about the line-up initially and we were still learning the tricks and ways a band gradually learns from experience- dealing with our tones, gear, trying to balance college life with this and later, trying out a lot of people (which was a frustrating time for us). Now we have the right people to deliver the right sound and take this journey in the right direction.How did it feel to perform with three other bands at Metal Battle I?These are one of the finest upcoming bands in the scene. We had heard a lot about Winter Gate. Silent Existence and Jehovah are killer too. What plans for 2013?We hope to play more gigs, travel to new places and let people know about what we do. Also, expect an independent album release.
This one’s for the photography enthusiasts. Time Out , a photo art exhibition by four prominent artists trying to portray the myriad facets of life and the real essence of small things in life . The Exhibition is an inspiration to take some ‘Time Out’ for leisure to wash out heart and souls. These masterpieces are showcasing an array of moments soaked in the beauty of life , enriched with divinity. The muse of Time Out was to capture the allure of candid expressions by presenting them in a frame. Also Read – ‘Playing Jojo was emotionally exhausting’The exhibition has the works of Ravi Dhingra, Moushumee K Jha, Shoba Jolly and Ahmed Firoz. Moushumee Jha is an accomplished photo artist whose sensitive frames capturing people, culture, street life have been appreciatedby photographers, designers and creative professionals all overthe world. Starting her artistic journey as an actress (TV, cinema, stage), Moushumee developed a keen sense of light and shade, frame angles and story-telling with minimalist subjects. She brings these experiences as well as her deeply artistic and rich cultural training to her photography. Moushumee has executed commissioned projects in Tourism, architectural and real estate projects, products, interiors, theme based personal portfolios. Her Work has been published in various magazines, News Papers, Corporate Brochures, and Documentation Journals. She has been in the panel of judges in various photography competitions and initiatives in Delhi. Also Read – Leslie doing new comedy special with NetflixMoushumee has authored 3 photo books – Ananya. Her journey through life in 2010, which was well appreciated by the viewers/readers. A coffee Table Book Celebrating Assam At SurajKund- a Visual Narration, for Assam Tourism in 2012, and Golf Tourism in Assam- a Tea Table Conversation, For ATDC in 2014.Ravi DhingraRavi pursued photography as a hobby till he joined Triveni Kala Sangam, New Delhi in 1998 to learn the finer nuances of the craft. With his photographs he tries to bring out the emotions attached with every subject- the state of happiness, feelings of being sad, neglect and plight. He wants the viewer to get involved with the photographs and feel the emotions. A chance assignment with a publication led to switching over from the hobby into a full fledged job. Since then he has been involved in Lifestyle photography which includes Interiors, Food, People and Product. He has been associated with leading publications, advertisement agencies and corporate clients and his work has been widely published in various books,magazines, brochures and on Web. Currently based in New Delhi, Ravi is also a visiting faculty for photography at various Institutes including National Institute of Fashion Technology since the year 2003. He is also a Co-Founder of a photography based organisation called Camera Unlimited Foundation. The organisation is involved in spreading knowledge and information related to photography through Workshops, Photo Walks and Tours. He has also curated a number of Photography exhibitions under the same banner involving upcoming and established photographer Shoba Jolly, a passionate photographer and avid traveller, loves practicing the art of seeing through her roving camera lenses. Her vivid and endearing images tell stories about people and places in far away lands. Originally a commerce student from Lady Shri Ram College, New Delhi, Shoba ran a plastic manufacturing industry for 22 years. Yearning to give vent to her creative side Shoba now concentrates on travel, landscape and fine art photography. She also shares her travel memoirs by writing articles accompanied by alluring photographs for various travel publication.When- March 27 to April 5Where- Arpana Caur Gallery at Academy of Fine Arts and Literature, 4/6 Sri Fort Institutional Area Time- 11am to 7pm
Darjeeling: Binay Tamang, chairman, Board of Administrators, Gorkhaland Territorial Administration, will convene a meeting with the authorities of University of North Bengal and principals of various hill colleges affiliated to the university on September 8 at the Lalkothi, the GTA secretariat in Darjeeling.The meeting is aimed at finding a solution to the impasses that have cropped up, with the university having introduced the Choice Based Credit System (CBCS). College authorities apprehend that the winter vacations will have to be done away with, under the CBCS. Also Read – Rain batters Kolkata, cripples normal lifeHill college students, anticipating multiple problems, especially in winters, had appealed for intervention by both the state government and Gorkhaland Territorial Administration (GTA). The students of Southfield College (formerly Loreto College, Darjeeling), recently submitted memorandums to the MLA, Darjeeling and chairman, GTA, requesting them to take up the matter with the state government. “The meeting will be attended by the Vice-Chancellor, registrar and secretary, Undergraduate Council of the University of North Bengal. The GTA aims at creating a conducive environment for students, hence the meeting has been convened to find a way out,” stated Tamang. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedThe GTA had written to the university for a meeting to resolve the impasse. In reply, the registrar, University of North Bengal, in a letter dated August 20, confirmed the participation of the university authorities on September 8. “The University of North Bengal has to conduct all the undergraduate examinations for its affiliated colleges, irrespective of locations of the hills and the plains. The stipulation of 90 teaching days per semester have the mandate of the UGC, which has to be followed while the undergraduate examinations are conducted,” stated the letter. The letter further stated that the university believes in deliberations and democratic practices. “The Vice-Chancellor shall certainly hear from the hill college principals to resolve the issue in the joint meeting,” added the letter. Under the CBCS system, examinations will be held every six months. Sessions will be from July to December and from January to June. The duration of each class will be for an hour, with 5 classes a day. There is no break in this system. Under the annual system, the hill colleges would break for winter recess in January and restart in mid-February. “We are anticipating curtailment of winter recess to accommodate this new system. This will cause numerous complications for students, especially girls,” stated Dipika Thapa, student representative, Southfield College.
Talented 16-year-old Sanjana Jain, disciple of Dr Raja Radha Reddy and Kaushalya Reddy’s will perform at her Rangpravesam at Kamani auditorium in the national Capital on Monday. Initiated into classical dance at a tender age of nine, Sanjana Jain has now blossomed into a full-fledged artist, ready to perform the Kuchipudi Rangapravesam. Rangapravesam is a Sanskrit word meaning ‘debut’. Ranga means ‘stage’ and Pravesam means entry. 16-year-old Sanjana is the disciple of Dr Raja Radha and Kaushalya Reddy and has done over 40 performances in India and overseas. She will begin her performance with Saraswati Vandana written by great and eminent Hindi Poet Suryakanth Tripathi Nirala for worldwide peace, prosperity, progress and fraternity. Also Read – ‘Playing Jojo was emotionally exhausting’This will be followed by Mandari Jatiswaram, Krishna Shabdam and Payo Ji Maine Ram Ratandhan Payo. She will also perform on Dev Stuti, a musical composition as an ode in praise of Goddess Parvathi, which will be followed by Tarangam based on Raag Mohan and Taal Adi. The Tarangam marks the climax of a traditional Kuchipudi recital. It depicts famous stories of Krishna’s childhood. This item ends with a display of exquisite virtuosity as the dancers execute intricate footwork patterns by dancing on the rim of a brass plate and coordinate them with complicated rhythmic patterns.Sanjana strives to continue this endeavour and achieve greater levels of merit in this field with the same drive and devotion. Speaking about her Rangapravesam, Sanjana says, “To do justice to the art, lucid imagination and long hours of practice is required to alter between different spaces to bring forth messages through abhinaya, facial expressions, and nritya, pure dance movement.
Kolkata: Barrackpore Police has arrested four persons for their alleged involvement in the murder of a Trinamool Congress activist, Satish Sharma.Sharma was shot at by some miscreants on Monday morning when he was sitting inside an under construction Kali puja pandal at Titagarh in North 24-Parganas. According to the investigation, police came to know that the miscreants had come riding a motorcycle. The victim was initially taken to B N Bose Hospital and later shifted to a private hospital Also Read – Rain batters Kolkata, cripples normal lifein the city. A bullet pierced his chest. Despite sustained efforts by the doctors, the victim succumbed to his injuries on Tuesday morning. The news of his death caused fresh tension at Titagarh where the incident occurred on Monday. Locals on Tuesday staged a protest demonstration against the incident. They alleged that the area often become a safe haven for criminals but the police have failed to take any steps against the miscreants. The family members of the victim lodged an FIR mentioning names of 10 people. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedOn the basis of the complaint lodged by the family members of the victim, police raided different areas of the district and arrested four persons — Bhola Prasad, Kala Munna, Seikh Samir and Sanjay Das. It was learnt from the police that Samir and Sanjay are locals. The accused were remanded to police custody after being produced before a Barrackpore court on Tuesday. Locals staged a protest demonstration in front of the police on Tuesday. The senior police officers assured locals that the criminals involved in the incident would be put behind bars soon. The angry mob also staged a black flag demonstration in the area. The agitation was later lifted following assurances from top cops of Barrackpore police commissionerate. The police are also conducting raids at various places in the district to nab other culprits involved in the crime.