New Study of Meteorite Provides More Evidence for Ancient Life on Mars

first_img Explore further Relic of life in that Martian meteorite? A fresh look ALH84001 HistoryScientists estimate that the meteorite, called Allan Hills 84001 (ALH84001), formed on Mars about 4.5 billion years ago, making it one of the oldest known objects in the solar system. Because the meteorite contains microscopic carbonate disks that are about 4 billion years old, scientists have previously hypothesized that the meteorite interacted with water that may have existed on Mars at this time.Much later, about 15 million years ago, a larger meteorite likely struck Mars and ejected ALH84001 into space. After spending most of that time traveling throughout the solar system, the meteorite landed on Earth about 13,000 years ago. Then, in 1984, a team of US scientists discovered it in Antarctica. The meteorite finally made news headlines in 1996, when NASA scientist David McKay and others peered at the rock under a scanning electron microscope and saw what appeared to be nanoscale fossils of bacteria-like life forms. Bacterial or Thermal Origin?Now, McKay, along with Kathie Thomas-Keprta, Everett Gibson, Simon Clemett, and Susan Wentworth, all of NASA’s Johnson Space Center, have revisited the original hypothesis with new observations of the meteorite. The study is published in a recent issue of the journal Geochimica et Cosmochimica Acta.In the new study, the scientists used advanced microscopy techniques to investigate the carbonate disks and, more importantly, the magnetite nanocrystals within the disks. These embedded magnetites are the apparent fossils that exhibit features similar to contemporary magnetotactic bacteria. During the past 13 years, different groups of scientists have proposed competing hypotheses to explain the origins of these magnetites. Some of the leading hypotheses are non-biological, suggesting that the magnetites were formed via thermal decomposition of the carbonates in which ALH84001 was struck by other meteorites. Such impacts may have increased the temperature of ALH84001 and caused the carbonates to decompose into magnetites via bond redistribution. In some models, ALH84001 may have experienced this shock by a random meteorite impact while still on Mars, while in other models, thermal decomposition may have occurred due to the impact event that ejected ALH84001 from its home planet. 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: K.L. Thomas-Keprta, S.J. Clemett, D.S. McKay, E.K. Gibson, and S.J. Wentworth. “Origins of magnetite nanocrystals in Martian meteorite ALH84001.” Geochimica et Cosmochimica Acta, 73 (2009) 6631-6677. (PhysOrg.com) — In 1996, when scientists examined a meteorite from Mars previously uncovered in Antarctica, they were intrigued by what looked like microscopic fossils of ancient Martian life forms. Now, using new technology that wasn’t available 13 years ago, NASA scientists have found further evidence that the materials and structures in the meteorite are likely signs of ancient life, rather than the results of inorganic processes.center_img But whatever event might have triggered a thermal decomposition process, the scientists argue in the current study that very few – if any – of the magnetites embedded in ALH84001 carbonates are a product of thermal decomposition. By analyzing details such as the percentage of magnetite volume in the carbonate disks, the trace amounts of impurities observed in some of the magnetites, and the lack of siderite which some previous models suggested may have decomposed to form magnetite, the scientists concluded that these new observations were inconsistent with the previous inorganic-based thermal decomposition hypotheses.By showing that it’s very unlikely that the magnetite originated from the decomposition of ALH84001’s carbonate, the scientists argue that possible biological origins of the magnetite need to be considered more seriously than before. “For the past 10 years, the leading (and only) viable non-biologic hypothesis for the origin of the nanophase magnetites concentrated in ALH84001 has been thermal or shock decomposition of iron-bearing carbonates, a process known to produce small magnetite crystals,” Thomas-Keprta told PhysOrg.com. “Our paper has falsified this non-biologic hypothesis by showing, based on thermodynamics and minor element chemistry, that this non-biologic hypothesis simply cannot produce the ultrapure magnetites actually present in ALH84001 as a significant population of all magnetites. By falsifying this non-biologic hypothesis, we are left with only the biologic hypothesis to explain the detailed properties of the magnetites in this martian meteorite.”Magnetite BiosignatureAlthough they have not yet developed a model for the origin of the magnetite in ALH84001, the researchers’ new observations are consistent with the possibility that the magnetite has an “allochthonous origin,” in which it was exposed to aqueous solutions such as water. As Thomas-Keprta explained, the magnetite in ALH84001 could have been one of several ferromagnetic minerals produced by magnetotactic bacteria that live in aquatic environments. When these bacteria die and their shells degrade, a chain of magnetite is released into the environment. Without its confining shell, the magnetite chain configuration cannot be maintained, so individual magnetite crystals begin to mix with inorganic particles in the water. On Earth, magnetotactic bacteria are quite common in aqueous environments, and scientists often find magnetites in surface and subsurface sediments. “For many years, the presence of the specific kind of nanomagnetite formed by magnetotactic bacteria on Earth have been completely accepted as a biosignature when found in any Earth sediment or rock,” Thomas-Keprta said, noting that these magnetite have very specific properties. “When we first documented these specific properties in the ALH84001 carbonates, the only alternate non-biologic hypothesis that was commonly accepted as viable was the thermal decomposition of iron-bearing carbonate,” she said. “Now that we have completely falsified this hypothesis with this latest paper, we are still left with the specific properties of the ALH84001 magnetite that, if found on Earth, would be a robust biosignature indicating production by bacteria.“We also point to the many discoveries since our original paper showing supporting evidence such as an early strong magnetic field on Mars (necessary for the development of magnetotactic bacteria); the presence of near surface water at many locations on current-day Mars; the presence of possible oceans, major drainage channels, and other features associated with an early wet Mars; and the recent evidence for variable releases of methane into the Martian atmosphere. . . . We do not believe it is too incautious to restate our original hypothesis that such magnetites constitute strong evidence of early life on Mars.” This image of the meteorite, seen through a scanning electron microscope, shows bumps that resemble a fossilized colony of microbacteria. Some of the rounded bumps are preserved at the top of the surface and resemble individual spherical and ovoid-shaped microbes. Image credit: NASA. Citation: New Study of Meteorite Provides More Evidence for Ancient Life on Mars (2009, December 17) retrieved 18 August 2019 from https://phys.org/news/2009-12-meteorite-evidence-ancient-life-mars.html Copyright 2009 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.last_img read more

Solar power installs almost doubled in 2010

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. Explore further Image: SEIA Germany to cut solar subsidies to households In the United States 956 megawatts worth of all types of solar power were installed in 2010. That gave a cumulative installed capacity of 2.6 gigawatts and while this may sound like a lot of solar power it is only enough to power about 500,000 homes, and it represents less than one percent of all of the installed electricity capacity in the country.Despite the relative scale of the contribution, this growth is still fairly impressive. When you compare it to numbers from the same report in 2009, the total value of solar installations was only $3.6 billion. In 2010 that total just about $6 billion. We can see that the capacity in dollar value almost doubled. Though not all solar sectors showed growth. One shrink of note was in the US’s share of photovoltaic installations, which slipped to 5 percent of the world’s total, down from 6.5 percent in 2009.The reports also show that some states that are doing better on the conversion to solar power than others. California did the most in cumulative capacity of solar installations. Other states with notable cumulative capacity of solar installations include New Jersey, Florida, Arizona, Nevada, Colorado and Pennsylvania, which between them accounted for 76 percent of the solar capacity installed in 2010.There are no predictions as to whether or not this trend will continue in 2011. Though, there is an industry wide goal of powering 2 million homes with solar power by 2015. (PhysOrg.com) — The report for 2010 was released by the Solar Energy Industries Association on the solar markets and installations of the United States, and it revealed that solar power is a growing market. More information: Report: seia.org/cs/news_detail?pressrelease.id=1292 Citation: Solar power installs almost doubled in 2010 (2011, March 11) retrieved 18 August 2019 from https://phys.org/news/2011-03-solar-power.html © 2010 PhysOrg.comlast_img read more

New theory shows oneway transmission materials should be possible for sound and

first_img(PhysOrg.com) — Physicist Stefano Lepri of the Italian National Research Council and his partner Giulio Casati of the University of Insubria, have published a paper in Physical Review Letters, where they demonstrate through mathematical theory that it should be possible to create asymmetric materials that allow most light or sound waves to pass through in one direction, while mostly preventing them from doing so when going the opposite way. Scientists have for years been trying to figure out if it was possible to get around the reciprocity theorem, which states that identical waves passing through the same medium should behave the same way regardless of direction. If such a feat were possible, true one-way mirrors could be created, or soundproof rooms, or taking it further, quantum computers that use light to perform calculations.Lepri and Casati, in their paper, propose the idea of constructing a material composed of several layers of ordinary linear material, such as glass or plastic, but that also has two nonlinear layers of material in the center. They then showed that because waves travel best through material when their frequency has a certain resonance with the material it passes through, it should be possible to create a nonlinear material that is fine tuned to allow the maximum amount of waves to pass through for a certain frequency, going a certain direction; but which would not generally be the case for waves traveling in the opposite direction. The result would be a material that lets through most of the waves traveling in one direction, but not the other.If such materials could be created, scientists envision not just custom building materials that could control how much heat or light comes through, while still allowing people to see out, or true one-way mirrors, or houses made with rooms that are nearly perfectly sound proof, but perhaps wave diodes that could be used in the same way as electronic diodes that allow current to run just one way through a system; paving the way for computers that operate at speeds we can only dream of today.Neither Lepri and Casati, nor anyone else has yet come up with a nonlinear material that can be fine tuned to provide the custom resonance required to create such a material, however, so for now, this new science is still just theory; the authors believe it’s just a matter of time though. © 2010 PhysOrg.com 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.center_img Citation: New theory shows one-way transmission materials should be possible for sound and light waves (2011, May 3) retrieved 18 August 2019 from https://phys.org/news/2011-05-theory-one-way-transmission-materials.html More information: Asymmetric Wave Propagation in Nonlinear Systems, Phys. Rev. Lett. 106, 164101 (2011) DOI:10.1103/PhysRevLett.106.164101AbstractA mechanism for asymmetric (nonreciprocal) wave transmission is presented. As a reference system, we consider a layered nonlinear, nonmirror-symmetric model described by the one-dimensional discrete nonlinear Schrödinger equation with spatially varying coefficients embedded in an otherwise linear lattice. We construct a class of exact extended solutions such that waves with the same frequency and incident amplitude impinging from left and right directions have very different transmission coefficients. This effect arises already for the simplest case of two nonlinear layers and is associated with the shift of nonlinear resonances. Increasing the number of layers considerably increases the complexity of the family of solutions. Finally, numerical simulations of asymmetric wave packet transmission are presented which beautifully display the rectifying effect. Physicists rotate beams of lightlast_img read more

Researchers build bench size laserpulsed neutron source

first_img World record neutron beam at Los Alamos National Laboratory © 2013 Phys.org Explore further (Phys.org)—Researchers from Institut für Kernphysik in Germany, working with colleagues from Sandia National Laboratories and Los Alamos National Laboratory, have succeeded in building a compact neutron source small enough to be used in a conventional lab. It’s based, the researchers report in their paper published in Physical Review Letters, on laser pulses directed onto a plastic target doped with deuterium atoms. Journal information: Physical Review Letters 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. Physics researchers around the world have been hoping someone would develop a neutron source small enough to fit in a conventional lab for several years, as neutrons have become an important means for studying the properties of many materials. Currently, most find it necessary to compete with other researchers for time at a nuclear reactor or dedicated accelerator facility to conduct such research. This new source method offers a possible alternative.To create their source, the researchers doped a thin sheet of plastic with deuterium atoms. It was placed just 5 nm in front of second target made of beryllium. A laser was then fired at the plastic sheet, penetrating and ionizing it – the liberated electrons were subsequently pushed to the back of the target causing the ions to accelerate further. When they struck the secondary target a nuclear reaction occurred, producing neutrons.The researchers found that their source was able to produce just 25 percent of the energy of other experimental sources, but the neutrons produced were 10 times as energetic and 10 times more plentiful. They also found that a number of the neutrons were emitted from the source in a forward facing direction, which the researchers note, is likely due to the type of nuclear reaction that took place. To demonstrate the usefulness of their source, the researchers took a series of radiographs by placing objects in front of the neutron beam and recording the shadows produced in a neutron detector.The researchers suggest that with fine tuning for commercialization, their device should be able to fit on a work bench, and that only the target would need shielding to protect researchers in the area. This they note would allow for lab based neutron experiments at the course level, giving students access to science previously reserved for a select few physicists who have access to large nuclear facilities. More information: Bright Laser-Driven Neutron Source Based on the Relativistic Transparency of Solids, Phys. Rev. Lett. 110, 044802 (2013) DOI: 10.1103/PhysRevLett.110.044802AbstractNeutrons are unique particles to probe samples in many fields of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to produce neutrons with energies in excess of 10 MeV. For more than a decade experiments have tried to obtain neutron numbers sufficient for applications. Our recent experiments demonstrated an ion acceleration mechanism based on the concept of relativistic transparency. Using this new mechanism, we produced an intense beam of high energy (up to 170 MeV) deuterons directed into a Be converter to produce a forward peaked neutron flux with a record yield, on the order of 1010  n/sr. We present results comparing the two acceleration mechanisms and the first short pulse laser generated neutron radiograph. Citation: Researchers build bench size laser-pulsed neutron source (2013, February 1) retrieved 18 August 2019 from https://phys.org/news/2013-02-bench-size-laser-pulsed-neutron-source.htmllast_img read more

Four base units of measure in the metric system about to be

first_imgCredit: CC0 Public Domain 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. © 2018 Science X Network More information: 26th meeting of the CGPM: 13-16 November 2018: www.bipm.org/en/cgpm-2018/ CGPM set to update international system of weights and measures Explore further Officials with the General Conference on Weights and Measures (CGPM) have announced that at a meeting to be held next week, four of the base units used in the metric system will be redefined. The four units under review are the ampere, kilogram, mole and kelvin. Citation: Four base units of measure in the metric system about to be changed (2018, November 9) retrieved 18 August 2019 from https://phys.org/news/2018-11-base-metric.html Currently, the kilogram is officially defined as the mass of a cylinder made of a platinum-iridium alloy housed in a bell jar in France—it has been removed from its protected spot every 40 years to serve as a calibration tool for other weights. But according to officials with CGPM, its days are numbered. This is because the 60 member nations that make up the body will be voting to change to a system in which the kilogram will be defined indirectly—by using the Planck constant. The tool used to provide the new base unit is the Kibble balance—a very complex piece of equipment that first measures the amount of electric current necessary to create an electromagnetic force that is equal to a force acting on a given mass. It is during the second stage that the Plank constant comes into play. The reason for the changeover is to reference a more stable basis of measurement and to allow for the development of more precise measuring devices. Several metrologists involved in bringing the changes to a vote have acknowledged that most people will neither understand the changes that have taken place, nor notice that a change has occurred.The metric system is part of the International System of Units, and in places other than the United States, is commonly called SI. Efforts to make it more precise have been underway for years. The speed of light, for example, was updated in 1983, and is now defined as 299,792,458 meters per second. For those interested in the proceedings, the CGPM will be streamed live on the internet. Officials have described the meeting as marking the end of SI measurements based on objects. Prior meetings have already resulted in updating the other three base units in the system: the second, meter and candela. If the measures pass, the changes will take effect in May of next year.last_img read more

Gods Robots descend

first_imgWhat began three years ago on the internet has come together in an album launch. Meet the Gods Robots – a powerhouse band that intrinsically started with Janaka and Shridevi and now a four member strong team with Alam Khan on the sarod, Suhel Yusuf Khan and Mike on the pipes. Shuffling between San Francisco and Mumbai, Gods Robots have picked the Capital to launch their first official album. Speaking about where it all began, Janaka says that he briefly met Shridevi in Mumbai and then heard her vocals on the internet. Shridevi has a simmilar story to tell about Janaka. But it was a matter of musical coincidence that both parties loved what they heard online and when Janaka wrote to Shridevi about working together – the Gods Robots were on their way. Also Read – ‘Playing Jojo was emotionally exhausting’Gods Robots define a brand new sound by seamlessly blending English lyrics with a pop music edge, classical Indian instrumentation and bass heavy underground rhythms. While Janaka brings in his electronic dance music, trance and dub-step to the sounds, Shridevi blends in the classical Indian and carnatic tunes to it. What results is something that Janaka descibes as – ‘Pop-electronic with bits of trance, break, dub-step on one level, classical and carnatic on another and western classical on a third plane with a strong reggae element’. Wow. Also Read – Leslie doing new comedy special with NetflixLate 2011 saw the band release their critically acclaimed Stormy Weather. In the very first week of its release their music video Stay topped the 100,000 views mark on youtube and is now hovering near 200,000. Gods Robots music has been hitting the international airwaves for a couple years now with BBC Radio 1 describing their music as ‘authentic’ and dubbing them ‘best sound’ and ‘the band to watch out for’ on the show The Strand. Their music is a regular featured on a number of BBC Radio shows. When asked if they had one name for the genre they play, Janaka says, ‘You cannot put a genre to the music Massive Attack makes, we aspire to make music like that.’ With infulences ranging from Lana Del Rey to Guns and Roses and a lot of 60’s music, this is clearly a band to watch out for. ‘Delhi has a great young classical music scene,’ says Janaka, adding that the lively presence and enthusiasm in the Capital is exactly what works for them and their kind of music. While Gods Robots have already performed in Sunburn, the Bombay Lit Fest and even the Jaipur Lit  Fest, they are looking forward to more shows across the country post their launch. With a world-wide launch on the cards soon – here’s hoping the Gods Robots land safe!last_img read more

Number of road accidents down by 22 in 2 years

first_imgKolkata: With the state-wide Safe Drive Save Life campaign launched by Chief Minister Mamata Banerjee, Bengal has witnessed a 22 percent reduction in road accidents in the first quarter of 2018, compared to the corresponding period in 2016. At the same time, the fatalities due to road accidents have also gone down by 18 percent in the same time period.The state police have prepared a comparative study on the number of road accidents that took place in the past three years in the areas under the jurisdiction of West Bengal Police and with the completion of the study by March-end, the police have come to know that the first three months of 2018 have recorded the least number of road accidents in the past three years. Also Read – Heavy rain hits traffic, flightsAccidents in the first quarter of 2018 were 15.5 percent less than in the corresponding period in 2017. The police have also compared the figure of 2018 with that of the same period in 2016, before the Safe Drive Save Life campaign was launched and it has revealed that there has been a drop in the rate of accidents by 22 percent.With the police taking up a massive campaign to create awareness on road safety measures, the number of lives claimed due to road accidents has also dropped by 18 percent in the first quarter of 2018, compared to the corresponding period in 2016. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedComparison of the figures have further revealed that there has been a 12 percent drop in fatal accidents in the first three months of 2018, compared to the corresponding period in 2017.Vivek Sahay, Additional Director General (Traffic and Road Safety), said: “As far as I can see from the police point of view, road safety has finally become a major area of concern for police. Earlier, road safety was not a major portion of activities and focus. So now, with the launch of Safe Drive Save Life by the Chief Minister, road safety has become an important part of action for the police. Besides continuing work to check crime and law and order issues, road safety related issues have also been taken up with equal importance and it has helped in reducing the number of road accidents.”The comparison of figures have also shown that in the month of March 2018, the number of fatalities due to road accidents has gone down by 20 percent, compared to that of March 2017.last_img read more

Breaking ice with The Iceberg Project

first_imgMusic reflects upon the emotions and feelings in the best way possible. Susmit Sen, one of India’s most celebrated and well-known guitarists and the founder of India’s most popular fusion band, Indian Ocean, has released a new single titled The Iceberg Project.The track features Susmit performing his trademark guitar work and it is a collaboration with cello player Tapan Malik, guitarist Nishant Agarwal and percussionist Varun Gupta.Poignant and melancholic at times, uplifting at others, The Iceberg Project is bound to impress the listeners. The composition is a projection of today’s darkness and how it is transformed into a positive world.  Also Read – ‘Playing Jojo was emotionally exhausting’The initial part of the composition questions every aspect of human existence and the latter focuses on how to change the same by diverting attention to the beauty that surrounds us. Launched in association with The Big Band Theory, The Iceberg Project is the culmination of an episodic series that highlighted the various stages of how an idea evolves through and the different elements and aspects in building an original composition.Talking about The Iceberg Project, Susmit Sen says, “It has been a great experience for me working on the composition. I think the track has been able to capture the emotions I wanted to convey. It has been great working with Tapan, Nishant and Varun as well and I would like to thank them for their contributions.” On naming the composition The Iceberg Project, Susmit says “Any creation is a manifestation of a creator’s feelings. Creations witnessed by the world are just the tip of an iceberg. The rest lie submerged – unheard, unseen…..”The Iceberg Project released on the world wide web on Sunday.last_img read more

2 more arrested over attack on MLAs car

first_imgKolkata: Baruipur police have arrested two more accused — Saiful Nashkra and Salaudin Seikh — for their alleged involvement in firing and hurling bombs at the car of Joynagar MLA Biswanath Das that eventually killed three persons including two Trinamool Congress workers.The incident occurred on December 13 when some miscreants hurled bombs at Das’s vehicle parked in front of a petrol pump at Joynagar in South 24-Parganas. Das had gone to the Trinamool Congress party office in the Baharu area and sent his driver along with another party worker to refuel his car. His driver parked it outside the petrol pump and went to have tea during Also Read – Rain batters Kolkata, cripples normal lifethe incident. After the incident, Das claimed that he was the target as he regularly visits the place to have tea from a stall there. On the day of the incident, he directly went to the party office as he was late. The district Trinamool Congress leaders alleged that it was a pre-planned attack by goons backed by an opposition party. Following the incident, the Superintendent of Police (SP), Baruipur Police District and other senior officers rushed to the spot and started a detailed probe. Police have so far arrested 14 persons in this connection. During investigation, the officers came to know that the MLA might not have been the target as they attacked after he got down from the car. Contract killer Babu Kahar, alias Babua, had received a contract. He has been absconding since the incident took place. The district police are conducting raids to nab the culprit. Police are interrogating and verifying the statements of the accused who have already been arrested in this connection. The district police believe they would be able to arrest the main accused Babua soon.last_img read more

Architectural photographs finds space in upcoming India Arch Dialogue

first_imgNew Delhi: Aiming to discuss, create and debate art, architecture and photography, the third edition of India Arch Dialogue is all set to begin. Starting from February 9, this three-week event, organised by FCDI, is themed “Moments in Architecture – An Exhibition on Architectural Photography, Talks and Events”.Curated by Verendra Wakhloo, Rachit Srivastva, Madhav Raman and Sudipto Ghosh, the event will see interactive sessions with the participation of several architects, artists and photographers across globe who are all masters in the industry with extraordinary skills and unequivocal excellence of design practice, who have worked towards shaping the face of architecture and design milieu. Also Read – Add new books to your shelfAbha Narain Lambah, Abin Chaudhuri, Aniket Bhagwat , Asim Waqif, Dominic Sansoni, Rohan Shivkumar and Partner – Avijit Mukul Kishore, Paul Clemence, Robert Greenwood, Iwan Baan annd Juergen Mayer are some of the architects whose work will be showcased. While visitors will get to see works of renowned photographers like André J. Fanthome, Bharath Ramamrutham, Dayanita Singh, Ram Rahman, Paul Clemence, Sebastian Cortés, Iwan Baan and Dominic Sansoni. Also Read – Over 2 hours screen time daily will make your kids impulsive”The very idea of the Indian Arch Dialogue is to be inclusive and provide an interactive platform for nationally and internationally distinguished architects and designers. Exhibitions, talks,workshops on architecture, art, fashion, photography generate a large resource of ideas,” Wakhloo said.Madhav Ram, another curator said: “This year, we have curated the best architectural photographs and some of the most creative minds from around the world to share their thoughts on photography. The idea is to help people connect with architecture and architecture to connect with people.”last_img read more