Scientists say plants can remember properties of light

first_img 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.last_img read more

Decoding early Martian weather Analyzing carbonate minerals in meteorite Allan Hills 84001

first_img Citation: Decoding early Martian weather: Analyzing carbonate minerals in meteorite Allan Hills 84001 (2011, October 24) retrieved 18 August 2019 from https://phys.org/news/2011-10-decoding-early-martian-weather-carbonate.html More information: Carbonates in the Martian meteorite Allan Hills 84001 formed at 18 ± 4 °C in a near-surface aqueous environment, Published online before print October 3, 2011, PNAS October 11, 2011 vol. 108 no. 41 16895-16899, doi:10.1073/pnas.1109444108 Explore further Led by Itay Halevy (currently at the Weizmann Institute of Science in Israel), along with Woodward W. Fischer and John M. Eiler, the research team faced a number of challenges. “The main challenge,” Halevy says, “was making an isotope clumping measurement on a precious, low-carbonate-abundance material.” Isotope clumping in carbonates denotes the tendency of heavy carbon and oxygen isotopes in carbonates (and in CO2) to bond with each other rather than with the elements’ lighter isotopes. This temperature-dependent tendency is the basis of multiply substituted (clumped) isotope thermometry. Clumped isotope thermometry is based on the tendency of heavy carbon and oxygen isotopes to bond with each other rather than with the lighter isotopes of these elements in a way that is effectively independent of the material’s isotopic composition: However abundant or rare the heavy isotopes are in a sample, they will still prefer to form bonds with each other, and this preference will always depend on temperature – and the colder it is, the higher the preference. “Other isotopic thermometers are based on the temperature dependence of the difference in chemical or isotopic composition between the aqueous solution and the carbonates that precipitate from it,” notes Halevy, “so to derive temperature one must know the chemical or isotopic composition of both the carbonates and the parent fluid. Unfortunately, it is impossible to know the composition of ancient fluids and so one must make some assumptions about their composition. Any temperature determined in this way is always dependent on these assumptions.” Clumped isotope thermometry avoids this because no matter how abundant the heavy isotopes are, they will always tend to bond in a temperature-dependent way.“The clumping measurement, developed by John Eiler and his students and postdocs at Caltech over the last seven to eight years, is itself challenging to make,” Halevy continues. The natural abundance of C-O clumps is only a few tens parts-per-million, which means you have to measure a lot of material to get a precise and accurate result – and we didn’t have a lot of material. ALH84001 is a 4-billion-year-old, originally 2 kg Martian rock; we had 5.5 grams, using 3 grams in the analysis – and of these 3 grams, only about 1% was carbonate minerals.” 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. While that was an appreciable amount of carbonate for a single clumping measurement, the researchers wanted to cut the gas into three measurements to get an internal stratigraphy (the study of strata, or layers) of the carbonate concretions. “To this,” Halevy comments, “add the increased risk of sample contamination associated with long acid digestion times – up to 12 hours for the more recalcitrant magnesium-rich carbonates – and you have the makings of an analytical challenge.”To overcome the low abundance of carbonate, the team performed a microvolume measurement. “Basically,” Halevy explains, “we froze the sample of CO2 gas released from the carbonates by acid digestion into a very small volume, shut it off from a lot of dead volume in the plumbing of the mass spectrometer, and thawed it in the small volume alone. The high pressure achieved by compressing the gas into a small volume allowed us to make the measurement under conditions that are close to the way the clumping measurement is typically made. Still, there are some important differences from a typical clumping measurement, so it took a lot of experimentation to map how the microvolume affected the results and to figure out ways to minimize these effects – or at least account for them.” As for the increased risk of contamination, the team performed extra purification steps to remove miscellaneous contaminants and again experimented extensively to convince themselves that the measurement was in no way compromised by the long reaction times.There are other innovations that could be applied to the protocol, mainly having to do with instrument improvements. “As mass spectrometers become more sensitive and are able to better differentiate between molecules of slightly differing mass,” Halevy explains, “low sample abundance and contamination will cease to be issues. A clumping measurement would be easier to make on small amounts of sample and any contaminations would be easily distinguishable from the CO2 molecules of interest. This would increase confidence in the measured temperature. “Halevy also points out that they developed the aquifer hypothesis on the basis of isotopic variability within the carbonate concretions and in light of the new insight that the temperature hovered around 20 °C. “Basically, given the temperature, the isotopic variability can only be explained by the drying-out of an aqueous reservoir that did not exchange CO2 freely with the atmosphere. The only environment we could come up with that meets these requirements is a subsurface aquifer. Increased confidence in the measured temperature would translate into increased confidence in this model for the formation environment of the carbonates.”Regarding computer modeling, Halevy says that while computer models are important for developing a quantitative understanding of analytical results, such as those presented in the paper, they can’t replace the measurements. “The measurements provide the physical constraints,” Halevy states, “and we can then use computer simulation to try and tease out information about process and environment.” In the team’s study, for example, measurements yielded the temperature and isotopic composition of the aqueous solution, while computer simulations allowed a quantitative estimate of how much of the water had to have evaporated, depending on the conditions of evaporation.In terms of applying their findings to exoplanetary exploration, Halevy stresses that “The mass spectrometers on or rovers, as well as the means for sample preparation and purification, would have to improve dramatically for a carbonate clumping measurement to be made in situ. Nevertheless, this may not be beyond the realm of possibility and may teach us much about aqueous processes on other planets. In addition, the ability to make a carbonate clumping measurement automatically implies the ability to measure clumping in CO2 and, therefore, the ability to explore certain atmospheric processes. Finally, clumping in molecules other than CO2 – such as organic molecules – may hold information not only about temperature, but the processes that formed them as well.”Halevy’s research will continue to include an analytical/experimental component and a modeling/simulation component. “Providing quantitative constraints on chemical processes on modern and ancient Mars will continue to feature prominently in my research,” Halevy concludes. “These same approaches will also be applied to understanding the geochemistry of Earth’s early oceans and atmospheric evolution.”center_img (PhysOrg.com) — While geological evidence points to the presence of liquid water on Mars during the Noachian epoch (the period from 4.5 to 3.5 billion years ago), determining the temperature of that water – a factor critical to the probability of its ability to support early life – has hitherto been impossible. Recently, however, researchers at California Institute of Technology Geological and Planetary Sciences have derived a precipitation temperature of 18 °C from carbonate minerals found in the 4.1 billion-year-old Allan Hills 84001 (ALH84001) meteorite. Although this ancient aquifer’s temperature was relatively mild, the researchers note that their findings do not necessarily demonstrate habitability. Copyright 2011 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. Model for carbonate formation in ALH84001. (A) Physical model of a shallow subsurface aquifer. The depth of carbonate formation is constrained by a combination of the cosmic ray exposure pattern of ALH84001 and Martian meteorite ejection models (48, 49). (B) Reduction of the physical model to a geochemical model of carbonate precipitation and CO2 degassing driven by gradual evaporation of water in a confined volume, coupled to loss of the vapor phase. Copyright (c) PNAS, doi:10.1073/pnas.1109444108 Wet and mild: Researchers take the temperature of Mars’s pastlast_img read more

Education social networking site Edmodo to open API to third party developers

first_img(PhysOrg.com) — Edmodo, the leading education centric social networking site has announced that it is opening its Application Programming Interface (API) to third party developers in a bid to entice more teachers to use the site. Edmodo is a Facebook-like site that is restricted to teachers, parents, students and school districts and is used primarily as an online tool between teachers and their students. It currently has a user base of approximately six million. By opening up their API, Edmodo is hoping to increase that number and to profit from its take on the applications that are created and sold for the platform. Citation: Education social networking site Edmodo to open API to third party developers (2012, March 7) retrieved 18 August 2019 from https://phys.org/news/2012-03-social-networking-site-edmodo-api.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. More information: Press release Teachers admit to bullying studentscenter_img Explore further Edmodo was founded in 2008 by Nicolas Borg and Jeff O’Hara and is based in San Mateo California. It’s currently available in English, Spanish, Portuguese, German, Greek and French and as a result is used by educators and students across the globe. To use the site, teachers create an account for themselves that includes a profile and a means for adding all of the students in a class. After that, teachers and their students can communicate back and forth, quizzes can be given, grades posted (privately) and questions can be asked and answered. The whole point is to facilitate a process outside of the normal learning environment of the classroom to allow both teachers and their students a secondary avenue for reaching goals in the educational process.By opening up their API, Edmodo will allow third party developers to create apps for the site that can be used in ways very similar to those users see on Facebook, except of course, the apps on Edmodo will all be aimed specifically at helping teachers teach, and students learn. To make sure that happens, Edmodo has created a sister site called the Teacher-Developer Exchange that provides a mechanism for teachers and developers to communicate with one another directly.To get the ball rolling, Edmodo has also announced that 35 initial apps are already available for download from its own apps store, some of which are free, while some are not. Edmodo gets a fifteen percent cut on each app sold. Apps are expected to range from learning games for the students, to addendums to textbooks, to processes that help teachers create and manage their lesson plans. What’s not clear yet is whether school districts will get in on the act and pay for the apps that teachers want to use or if Edmodo will offer discounts for school districts that do so. © 2011 PhysOrg.comlast_img read more

Researchers use Doppler Effect for computer gesture control

first_img © 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.last_img read more

Investigation reveals birds on roads adapt to speed limits

first_img 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.last_img read more

Researchers report first observation of early stages of creation of a starforming

first_imgA 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 refurbishmentcenter_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. 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: http://xxx.tau.ac.il/abs/1505.01290AbstractWhen cosmic star formation history reaches a peak (at about redshift z ≈ 2), galaxies vigorously fed by cosmic reservoirs are dominated by gas and contain massive star-forming clumps, which are thought to form by violent gravitational instabilities in highly turbulent gas-rich disks. However, a clump formation event has not yet been observed, and it is debated whether clumps can survive energetic feedback from young stars, and afterwards migrate inwards to form galaxy bulges. Here we report the spatially resolved spectroscopy of a bright off-nuclear emission line region in a galaxy at z = 1.987. Although this region dominates star formation in the galaxy disk, its stellar continuum remains undetected in deep imaging, revealing an extremely young (less than ten million years old) massive clump, forming through the gravitational collapse of more than one billion solar masses of gas. Gas consumption in this young clump is more than tenfold faster than in the host galaxy, displaying high star-formation efficiency during this phase, in agreement with our hydrodynamic simulations. The frequency of older clumps with similar masses, coupled with our initial estimate of their formation rate (about 2.5 per billion years), supports long lifetimes (about 500 million years), favouring models in which clumps survive feedback and grow the bulges of present-day galaxies. Explore further Journal information: Naturelast_img read more

Unintended consequences of creating the worlds first semisynthetic organism

first_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.last_img read more

New hot Jupiter with short orbital period discovered

first_img(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.last_img read more

Skull fragments suggest Iron Age Celts in southern France tried to embalm

first_img Explore further More information: Salma Ghezal et al. Embalmed heads of the Celtic Iron Age in the south of France, Journal of Archaeological Science (2018). DOI: 10.1016/j.jas.2018.09.011 © 2019 Science X Network A team of researchers from University Paul-Valéry Montpellier and UMR-IMBE, Université d’Avignon has found evidence of possible embalming of severed heads by Iron Age Celts living in southern France. In their paper published in Journal of Archaeological Science, the group describes their study of skull fragments excavated at a dig site near Le Cailar, in southern France, and what their analysis found. Pictures of a. Total assemblage b. CLR K16 R9 286 exterior surface c. CLR N17 R3 53 interior surface cranial fragments (after Ghezal and Gosnell). Credit: Journal of Archaeological Science (2018). DOI: 10.1016/j.jas.2018.09.011 Skull fragments with carved long, deliberate lines found at Gobekli Tepecenter_img Citation: Skull fragments suggest Iron Age Celts in southern France tried to embalm severed heads (2019, February 5) retrieved 18 August 2019 from https://phys.org/news/2019-02-skull-fragments-iron-age-celts.html The researchers were studying skull fragments uncovered at Le Cailar—to date, over 100 have been found. The skulls are believed to be those of enemy combatants who lost their heads after losing their lives in battle. The fragments have been dated back to the third century BC—a time when the town was a Celtic settlement.The researchers report that many of the skulls had cuts indicating they had been decapitated, and some also had marks suggesting the brains had been removed. In some cases, tongues had also been removed. To learn more about the history of the skulls, the researchers ground up small portions of several specimens into dust, and then subjected the dust to gas chromatography-mass spectrometry testing. They report that they found small amounts of diterpenoic compounds in several of the fragments, which are molecules that are produced when conifer resins break down, typically when heated. They also found evidence of cholesterols and fatty acids. As a control, the researchers performed the same tests on animal skulls that had been dug up at the same dig site—none of them had evidence of conifer resin.The researchers suggest the resin within the skull fragments resulted from dipping the skulls in a resin-based liquid as a means of slowing decay—a form of embalming. They note also that all of the skull fragments were found inside the walls of the compound, suggesting that the heads had been mounted for those living inside, rather than as a means of frightening would-be attackers.The researchers also report that they have not yet found any evidence that might explain the reason for embalming the heads, but suggest it might have been a means of showing respect to well-known warriors. The hope to learn more as excavation continues at the site. Journal information: Journal of Archaeological Science 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.last_img read more

Can Big Science Be Too Big

first_img— Modern science is largely a team sport, and over the past few decades the makeup of those teams has shifted, from small groups of collaborators to ever larger consortiums, with rosters far longer than that of the New England Patriots. Answering big questions often requires scientists and institutions to pool resources and data, whether the research involves detecting gravitational waves in deep space, or sorting out the genetics of brain development. Psychologists have found that people working in larger groups tend to generate fewer ideas than when they work in smaller groups, or when working alone, and become less receptive to ideas from outside. Why that would be isn’t entirely clear, but it runs counter to intuition, said Suparna Rajaram, a professor of psychology at Stony Brook University. Read the whole story: The New York Timescenter_img But that shift has prompted scientists to examine the relative merits of small groups versus large ones. Is supersizing research projects the most efficient way to advance knowledge? What is gained and what, if anything, is lost?last_img read more