Citation: Scientists say plants can remember properties of light (2010, July 16) retrieved 18 August 2019 from https://phys.org/news/2010-07-scientists-properties.html More information: via BBC 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 The images showed chemical reactions in leaves that were not exposed to light (PhysOrg.com) — Researchers in Poland say plants are able to remember and react to information on light intensity and quality by transmitting information from leaf to leaf. © 2010 PhysOrg.com Internal clock, external light regulate plant growth The scientists, led by Professor Stanislaw Karpinski of the Warsaw University of Life Sciences, used fluorescence imaging to view the response of specimens of the Arabidopsisa plant to light shone on them. They found that when light was shone on one leaf at the bottom of the plant the entire plant responded. The response, in the form of a cascade of chemical reactions induced by the light, continued even after the light source was removed, suggesting the plant was remembering the information contained in the light.Karpinski and colleagues discovered that when light is shone on a leaf a chemical reaction begins in one leaf cell and the reaction is immediately signaled to the rest of the plant by photo-electro-physiological signals (PEPS) from specialized cells called bundle sheath cells. Karpinski said the cells function in a similar way to a nervous system in animals.Professor Karpinski said animals have a “network of neurons, synapses, electro-physiological circuits and memory, but plants have their network of chloroplasts (connected by stromules), photo-electro-physiological signals transduced by bundle sheath cells, and cellular light memory.”Another discovery made by the team was that the plants responded differently to red, white and blue light. Karpinski thought the different responses might produce chemical reactions that protected the plant against disease. To test this idea the team shone light on the plant for an hour and then infected it with either bacteria or viruses.The results showed that if plants were infected before having the light shone on them there was no resistance to the disease, but if the light was shone on them for an hour and then they were infected 24 hours later, the plants did resist the infection. Karpinski said this demonstrated exposure to the light built up the plant’s immunity to pathogens, and that they were able to adjust to varying light conditions. Karpinski said that the quality of light varies from season to season and it appears the plants might use the information in the light to determine the season and immunize themselves against diseases prevalent at that time of year.The findings were presented at the annual meeting of the Society for Experimental Biology in Prague, Czech Republic.
© 2012 Phys.Org (Phys.org) — Researchers from Microsoft and the University of Washington have together created a system whereby a computer user can use hand gestures to instigate a limited set of computer commands such as scrolling and mimicking mouse double-clicking, that uses nothing but inaudible sound and doesn’t require any hardware other than a standard computer microphone and speakers. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen The system is based on the now famous Doppler Effect, whereby the frequency of sound waves changes as an object making noises passes by another that hears it. In the real world, most recognize it as the way sirens appear to change the way they sound when an emergency vehicle passes by. With this new system, the engineers record the change in frequency of a tone (20 and 22 kilohertz, beyond normal hearing range) generated by the computer’s speaker using the computer’s microphone, when an object, such as a hand passes by. Software, the team calls SoundWave analyzes the frequencies and converts them to computer commands. It can also be used with a Smartphone. 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: SoundWave: Using the Doppler Effect to Sense Gestures (research paper)Project page: research.microsoft.com/en-us/u … roups/cue/soundwave/ Microsoft Kinect makes moves on computers Explore further Play Video credit: Dan Morris and Desney Tan Thus far, the team has managed to capture five basic variables involved with the change in frequency: velocity, direction, proximity, the size of the object and time variation. By capturing and measuring these variables when hand gestures are made in front of a computer, SoundWave is able to perform scrolling, recognize tap and double tap (mimic mouse clicks) perform a two handed seesaw (to turn objects on screen) and recognize sustained motion. The result is a system that is good enough to allow a computer user to play a game of Tetris without ever touching the computer. It also can be made to recognize when a person approaches a computer, causing it to wake up, or to go back to sleep as soon as the person leaves.The team has tested the software on a multitude of different kinds and brands of computers using existing hardware and has found that no tweaking was necessary to perform basic functions and overall commands were executed correctly ninety percent of the time. They also tested the system using a variety of users and in several environments, including a noisy cafeteria and found the software worked reliably in virtually every scenario.At this point, it appears the team is positioning the SoundWave software as an add-on to computers, serving to fill in some of the gaps in other gesture based systems (such as Microsoft’s Kinect) that rely on cameras and other sensors. They are set to submit a paper for review describing the SoundWave system at the upcoming ACM SIGCHI Conference on Human Factors in Computing. Citation: Researchers use Doppler Effect for computer gesture control (2012, May 7) retrieved 18 August 2019 from https://phys.org/news/2012-05-doppler-effect-gesture.html SoundWave allows non-contact, real time in-air gesture sensing on existing commodity computing devices.
Journal information: Biology Letters New evidence suggests some birds gave up flight to become better swimmers Explore further Most drivers upon encountering birds in the roadway assume that the birds are attempting to gauge their speed and then take flight just before they arrive. This new study by the pair in France suggests that’s not how it works at all—instead, birds note how fast cars travel over many days, weeks, months, etc. and build a memory map based on the average speed of such vehicles. When a car approaches, they then pull that data from their brains and use it to decide when to fly away when a car approaches.The researchers found this out by using a stopwatch to measure how much time birds took to take off from the roadway ahead of them as they drove, which they called the Flight Initiation Distance (FID) and then by stopping to measure the distance traveled. They then set about changing their speed relative to the speed limit, sometimes driving under, over or at the set limit. They also tested birds on different roads with different posted limits, from 20 to 110 kmph. In so doing, they found that the birds studied did not try to guess how fast an individual car was traveling, but instead relied on average speed estimates they’d learned from observing traffic patterns on different roads. They also found that the birds tended to take flight earlier if they were standing in the middle of the road rather than to the side.In all the team recorded 134 instances of birds taking flight, with over 20 species measured. They noted that larger or heavier birds tended to have longer FIDs then did small agile birds and that FIDs grew longer for all species as the speed limit increased. They suggest most collisions with birds on roadways come about due to drivers exceeding the speed limit, catching the birds by surprise. Citation: Investigation reveals birds on roads adapt to speed limits (2013, August 21) retrieved 18 August 2019 from https://phys.org/news/2013-08-reveals-birds-roads-limits.html (Phys.org) —Two biologists from Canada working in France have found that birds that land on roads adapt to average highway speeds—the higher the speed limit, the sooner they take flight when a car approaches. In their paper published in the journal Biology Letters, Pierre Legagneux and Simon Ducatez of the University of Quebec and McGill University respectively, describe the field study they conducted timing birds on roads in France. More information: European birds adjust their flight initiation distance to road speed limits, Biology Letters, Published 21 August 2013 DOI: 10.1098/rsbl.2013.0417AbstractBehavioural responses can help species persist in habitats modified by humans. Roads and traffic greatly affect animals’ mortality not only through habitat structure modifications but also through direct mortality owing to collisions. Although species are known to differ in their sensitivity to the risk of collision, whether individuals can change their behaviour in response to this is still unknown. Here, we tested whether common European birds changed their flight initiation distances (FIDs) in response to vehicles according to road speed limit (a known factor affecting killing rates on roads) and vehicle speed. We found that FID increased with speed limit, although vehicle speed had no effect. This suggests that birds adjust their flight distance to speed limit, which may reduce collision risks and decrease mortality maximizing the time allocated to foraging behaviours. Mobility and territory size are likely to affect an individuals’ ability to respond adaptively to local speed limits. © 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.
A massive, very young clump in a disk galaxy at z = 1.987. Credit: Nature 521, 54–56 (07 May 2015) doi:10.1038/nature14409 (Phys.org)—An international team of space scientists has identified and observed the early stages of the creation of a star-forming clump, the first ever observed. In their paper published in the journal Nature, the team describes how they analyzed imaging and spectroscopy from the Hubble Space telescope to identify the clump, which they believe is likely to one day form a star. © 2015 Phys.org Citation: Researchers report first observation of early stages of creation of a star-forming clump (2015, May 7) retrieved 18 August 2019 from https://phys.org/news/2015-05-early-stages-creation-star-forming-clump.html As the team reports, star forming clumps come about in dense clouds of gas and dust which are known as dark nebulae—in such clouds, particularly in dense portions, the materials tend to coalesce due to gravitational attraction, into clumps—these clumps eventually evolve into proto-stars, and then finally stars. The galaxy under observation (in the cluster CL J144910856) was calculated to have come into existence approximately three billion years after the Big Bang—making it less than ten million years old. Dark nebulae that produce stars are known informally as star factories and the team suggests that they are responsible for the formation of the central bulge in spiral galaxies. They estimate the clump they have been studying has up to a billion bits of material and note that it was only because of the very high resolution offered by the Hubble telescope that they were able to make the discovery at all. They also suggest that their observations indicate that star formation regions are rare, but when they do exist, tend to have a very long lifespan. Thus far, they report, they have studied 68 galaxies in the cluster for signs of rapid star formation.It is hoped that the finding by the team will lead to a better understanding of star formation and by extension, galaxy formation, particularly in the early years of the universe. The clump under observation in this latest observation is believed to be very young, which could offer clues as to its initial state—currently the process by which clumps start to form is not really understood.The researchers suggest that many more such clumps, particularly larger samples, will need to found and studied before true insights into the nature of early star formation can be gained. Image: Hubble eyes galactic refurbishment 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: An extremely young massive clump forming by gravitational collapse in a primordial galaxy, Nature, 521, 54–56 (07 May 2015) DOI: 10.1038/nature14409 . Arxiv: https://sp2.img.hsyaolu.com.cn/wp-shlf1314/2020/IMG8205.jpg” alt=”last_img” />
(Left) The different molecular structures of the two natural base pairs (black) and the artificial base pair (red and blue) cause the base pairs to absorb light at different wavelengths, as shown at right. The average solar spectrum reaching the Earth’s surface is shown in orange, and the emission spectrum from standard fluorescent lighting is in yellow. Credit: Pollum et al. ©2016 American Chemical Society To investigate how this light absorption difference may affect living cells, the researchers in the new study performed an experiment with living cancer cells from human skin (epidermoid carcinoma cells). When exposed to a low dose of near-visible light, cells that had not been treated with the artificial nucleoside d5SICS exhibited no change in cell survival. Cells that had been treated with the artificial nucleoside, but not exposed to near-visible light, were similarly unaffected. But cells containing the artificial nucleoside that were briefly exposed to near-visible light exhibited a substantial decrease in cell proliferation, indicating that the artificial nucleoside had photosensitized these cells to near-visible light, resulting in photochemical damage. (Left) When exposed to low doses of near-visible light, living skin cancer cells that contain d5SICS exhibit a large decrease in cell proliferation compared to those not exposed to the light. (Right) Cells with d5SICS exposed to near-visible light show high levels of reactive oxygen species (ROS), as seen by the fluorescence of the ROS dye, compared to cells with d5SICS that were not exposed to the light. Credit: Pollum et al. ©2016 American Chemical Society Explore further Citation: Unintended consequences of creating the world’s first semisynthetic organism (2016, September 12) retrieved 18 August 2019 from https://phys.org/news/2016-09-unintended-consequences-world-semisynthetic.html © 2016 Phys.org Based on further investigation, the researchers think that one of the most probable mechanisms of the light-induced damage is that light exposure produces reactive oxygen species (ROS) inside the cells. High levels of ROS are known to cause cell damage, and the living cells containing the artificial nucleoside exhibited much higher levels of ROS upon exposure to near-visible light than untreated cells did.Overall, the results illustrate the complexities involved in the ways that making even a small modification to an organism’s genetic code may have far-reaching and unforeseen consequences for the entire organism.The upside, however, is that some of the unforeseen consequences may have benefits if used in a controlled way. For instance, the researchers are currently investigating how the phototoxicity of the artificial nuceloside could be used as a method to treat cancer.”The significant phototoxic activity of d5SICS in epidermoid carcinoma cells has the potential to open new opportunities for its use in topical photodynamic therapy applications, as our group and others have recently proposed for several nucleobase analogues,” Crespo-Hernández said.The authors acknowledge funding from the National Science Foundation CAREER Program (Grant CHE-1255084 and CHE-1539808). Chemists create mimic of key vision protein More information: Marvin Pollum et al. “Unintended Consequences of Expanding the Genetic Alphabet.” Journal of the American Chemical Society. DOI: 10.1021/jacs.6b06822 Journal information: Journal of the American Chemical Society (Phys.org)—In 2014, the incorporation of two artificial letters of genetic code into the DNA of Escherichia coli gave the bacteria the distinction of becoming the world’s first stable semisynthetic organism. The modification was intended to illustrate the possibility of enabling organisms to incorporate and replicate an artificial base pair for the future biosynthesis of novel proteins. But now in a new study, scientists have discovered that the artificial base pair has an unintended consequence on living cells: phototoxicity. The new results show that the artificial base pair makes living cells more susceptible to damage from low doses of sunlight and standard fluorescent light bulbs, leading to a significant decrease in cell survival and growth.The study, titled “Unintended Consequences of Expanding the Genetic Alphabet,” is published in a recent issue of the Journal of the American Chemical Society by a team of researchers led by Carlos E. Crespo-Hernández from Case Western Reserve University, along with coauthors from Case Western and Columbia University.”There is currently an ongoing quest to genetically modify living cells and organisms with different purposes,” Crespo-Hernández told Phys.org. “Our work clearly cautions scientists that care must be exercised when efforts are made to expand the genetic alphabet, especially if the synthetic organisms may be exposed to light—a fact that has been hitherto overlooked.”The artificial base pair consists of two nucleosides (which are nucleotides without a phosphate group) called d5SICS and dNaM. These artificial nucleosides have different chemical structures than the natural nucleosides, which are those made of the adenine, guanine, thymine, and cytosine nucleobases. Due to their different chemical structures, the artificial and natural nucleosides absorb light at different wavelengths. The artificial nucleosides strongly absorb light with wavelengths in the near-visible range, or just under 400 nm. In contrast, natural nucleosides absorb light most strongly at higher energies, those with wavelengths less than 300 nm. Since everyday lighting, such as the sunlight that reaches Earth’s surface and fluorescent light bulbs, contains much more light in the near-visible range than in the higher-energy ultraviolet range, we receive significantly greater exposure to light with near-visible wavelengths. 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.
(Top) The TRES RV measurements of KELT-20b with the best fit model shown in red. The residuals to the fit are shown below. (Bottom) The RV measurements phase-folded to the global fit determined ephemeris. The predicted RM effect is shown at 0.25 phase. The residuals are shown below. Credit: Lund et al., 2017. Citation: New ‘hot Jupiter’ with short orbital period discovered (2017, July 12) retrieved 18 August 2019 from https://phys.org/news/2017-07-hot-jupiter-short-orbital-period.html ‘Hot Jupiter’ transiting a rapidly-rotating star discovered © 2017 Phys.org More information: KELT-20b: A giant planet with a period of P~ 3.5 days transiting the V~ 7.6 early A star HD 185603, arXiv:1707.01518 [astro-ph.EP] arxiv.org/abs/1707.01518 (Phys.org)—An international team of astronomers reports the discovery of a new “hot Jupiter” exoplanet with a short orbital period of just three and a half days. The newly detected giant planet, designated KELT-20b, circles a rapidly rotating star known as HD 185603 (or KELT-20). The finding was presented in a paper published July 5 on arXiv.org. Explore further The new planet was identified by a group of researchers led by Michael Lund of the Vanderbilt University in Nashville, Tennessee. The astronomers observed HD 185603 using the KELT-North telescope in Arizona to identify the initial transit signal of a potential planet. The observations were made as part of the Kilodegree Extremely Little Telescope (KELT) survey, which is dedicated to searching for transiting exoplanets around bright stars.The observational campaign was carried out from May to November 2014, and allowed the scientists to identify KELT-20b as an exoplanet candidate. Afterwards, the researchers analyzed archival data and conducted follow-up observations and high-resolution imaging of the object, which resulted in confirming the planetary status of KELT-20b.”We identified the initial transit signal in KELT-North survey data. Archival and follow-up photometry, the Gaia parallax, radial velocities, Doppler tomography, and adaptive optics imaging were used to confirm the planetary nature of the companion and characterize the system,” the authors wrote in the paper.According to the study, KELT-20b has a radius of about 1.73 Jupiter radii and a maximum mass of 3.5 Jupiter masses. It orbits its host every 3.47 days at a distance of approximately 0.05 AU. The planet’s equilibrium temperature is about 2,261 K.The derived parameters of KELT-20b indicate that is belongs to group of planets known as “hot Jupiters.” These exoworlds are similar in characteristics to the solar system’s biggest planet, with orbital periods of less than 10 days. They have high surface temperatures, as they orbit their host stars very closely.The researchers emphasized that the newly discovered planetary system is extraordinary in several ways and that the planet itself is unusual when compared to other “hot Jupiters.””The KELT-20 system represents one of the most extreme transiting hot Jupiter systems, and indeed, one of the most extreme transiting exoplanet systems yet discovered by several measures. The host star is both exceptionally bright (V ∼ 7.6), and exceptionally hot (Teff ~ 8,700 K). It is only the sixth A star known to host a transiting giant companion. The planet itself is on a relatively short period orbit of P ~ 3.5 days, and thus receives an extreme amount of stellar insolation, resulting in an estimated equilibrium temperature of ∼ 2,250 K,” the team concluded.They added that KELT-20b is a great example of a “hot Jupiter” suffering from extreme stellar irradiation, particularly in ultraviolet wavelengths. Therefore, the planet is an excellent target for detailed follow-up observations and characterization. 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.