Are brains shrinking to make us smarter? Citation: Farming to blame for our shrinking size and brains (2011, June 15) retrieved 18 August 2019 from https://phys.org/news/2011-06-farming-blame-size-brains.html A fossil of modern humans, dating back 160,000 years. Photo © 2000 David L. Brill, Brill Atlanta While the change to agriculture would have provided a plentiful crop of food, the limiting factor of farming may have created vitamin and mineral deficiencies and resulted in a stunted growth. Early Chinese farmers ate cereals such as rice which lacks the B vitamin niacin which is essential for growth.Agriculture however does not explain the reduction in brain size. Lahr believes that this may be a result of the energy required to maintain larger brains. The human brain accounts for one quarter of the energy the body uses. This reduction in brain size however does not mean that modern humans are less intelligent. Human brains have evolved to work more efficiently and utilize less energy. (PhysOrg.com) — At Britain’s Royal Society, Dr. Marta Lahr from Cambridge University’s Leverhulme Centre for Human Evolutionary Studies presented her findings that the height and brain size of modern-day humans is shrinking. Explore further
(Phys.org) — Researchers have known for some time that young male fruit flies learn over time to bypass females that have already mated with someone else, but until now, no one really understood the mechanism involved. Now a team from Austria has discovered, as they write in their paper published in the journal Nature, that the when male fruit flies mate with females, they leave behind a bit of pheromone that serves as a signal to other males letting them know that further mating is futile. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Journal information: Nature Citation: Researchers discover how fruit flies learn to bypass already mated females (2012, August 20) retrieved 18 August 2019 from https://phys.org/news/2012-08-fruit-flies-bypass-females.html To come to these conclusions, the team ran a series of experiments to conclusively demonstrate exactly what was going on with the fruit flies. To begin, they first isolated the pheromone they thought was involved, cVA. Pheromones are chemicals produced by an organism that are believed to serve a signaling purpose when they are noted by others. In studying the fruit flies, the team noted that small amounts of cVA were deposited onto to the bodies of females, by males, during mating.To find out if cVA was serving as a signal for other males, the researchers modified several of them to prevent them from being able to smell or sense the presence of cVA. Those males then attempted to mate with females that had already mated, in essence demonstrating an inability to learn to tell the difference between mated and unmated females.In another experiment, the researchers genetically altered several female fruit flies to cause them to produce cVA on their own. This caused all the males (that had learned to do so) to bypass them.These two experiments convinced the team that it was the depositing of cVA on the females that signaled to latter males that the female was already mated and thus attempting to do so would be futile; they should instead move on. But that still didn’t explain how the young males learned to recognize the signal. To uncover that mystery, the team looked at dopamine levels in the brains of the fruit flies.In humans, dopamine is a pleasure chemical, it’s what drives cocaine addiction. But in insects such as the fruit fly, dopamine has been shown to be involved in learning. As the young males come into contact with the females for mating purposes, dopamine levels fluctuate, causing them to learn to associate rejection with the sensing of the cVa pheromone, which in turn leads them to avoid those already mated females to focus on the virgins instead.This bit of research shows that even the lowly fruit fly can learn based on environmental conditions and to adjust its behavior accordingly, which means, everything for them is not hard-wired. © 2012 Phys.org Researchers discover fruit fly aphrodisiac More information: Dopamine neurons modulate pheromone responses in Drosophila courtship learning, Nature (2012) doi:10.1038/nature11345AbstractLearning through trial-and-error interactions allows animals to adapt innate behavioural ‘rules of thumb’ to the local environment, improving their prospects for survival and reproduction. Naive Drosophila melanogaster males, for example, court both virgin and mated females, but learn through experience to selectively suppress futile courtship towards females that have already mated1. Here we show that courtship learning reflects an enhanced response to the male pheromone cis-vaccenyl acetate (cVA), which is deposited on females during mating and thus distinguishes mated females from virgins. Dissociation experiments suggest a simple learning rule in which unsuccessful courtship enhances sensitivity to cVA. The learning experience can be mimicked by artificial activation of dopaminergic neurons, and we identify a specific class of dopaminergic neuron that is critical for courtship learning. These neurons provide input to the mushroom body (MB) γ lobe, and the DopR1 dopamine receptor is required in MBγ neurons for both natural and artificial courtship learning. Our work thus reveals critical behavioural, cellular and molecular components of the learning rule by which Drosophila adjusts its innate mating strategy according to experience. Explore further
In addition to performing dynamic studies on the cloaks described in the paper, the scientists are now searching for new ways to cloak, as well as a method for introducing the cloaking concept into additional dimensions. “Our approach can help design strong materials in complex shapes without losing the performance of the initial material. We hope to use this approach in the engineering sciences to find a way to design complex architectures in a lightweight fashion – specifically in civil engineering and the automotive industry, where low weight and strong lattice-based materials will be, and in fact already are, a key future technology. For example,” Bückmann illustrates, “think about a door in a carbon-enforced car. Here one would directly find the right fiber directions to enforce the opening in the car without losing the car’s overall stiffness.” Journal information: Proceedings of the National Academy of Sciences Citation: Occam’s razor redux: A simple mathematical approach to designing mechanical invisibility cloaks (2015, May 1) retrieved 18 August 2019 from https://phys.org/news/2015-05-occam-razor-redux-simple-mathematical.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2015 Phys.org Measured performance of a lattice-transformation cloak. Same as Fig. 2, but measured directly on polymer structures fabricated by a 3D printer. Photographs of the structures are shown in the left-hand-side column. Again, the large distortions introduced by the hole in the homogeneous lattice are dramatically reduced in presence of the cloak, i.e., the average relative error with respect to the reference case, Δ, decreases from 714% to 26% in good agreement with theory shown in Fig. 2. Parameters are: r1 =30 mm, r2 =60 mm, L=4 mm, a = √3 × L, w =0.4 mm, and W =1 mm. Credit: Bückmann T, Kadic M, Schittny R, Wegener M (2015) Mechanical cloak design by direct lattice transformation, Proc Natl Acad Sci USA 112(16):4930-4934. An interesting limitation to the new approach – which is applied to the cloaking of a void in a lattice material – is that cloaking will never be perfect. “This is rather a general statement, as one needs to keep in mind that a perfect cloak is directly linked to material parameters that diverge,” Bückmann tells Phys.org. “This means if one would like to cloak an object, infinite materials parameters occur, such as an infinite mass at the inner cloaking radius – and this cannot be fulfilled in an actual experiment. One needs thus to consider how well an actual cloak performs, that is, Am I able to detect the imperfections, or do I care at all about them? This in turn depends on the problem one needs to solve, and cannot be answered in general.” In short, mathematically perfect cloaking is unavoidably connected with singular material parameters that just cannot be achieved in reality. More information: Mechanical cloak design by direct lattice transformation, Proceedings of the National Academy of Sciences (2015) 112(16):4930-4934, doi:10.1073/pnas.1501240112Related:1An elasto-mechanical unfeelability cloak made of pentamode metamaterials, Nature Communications (2014) 5:4130, doi:10.1038/ncomms5130 Images of samples and setup. Photographs of fabricated samples in the measurement setup including the Hooke’s springs that approximate constant pressure on the left- and right-hand side. From Upper to Lower: reference sample, sample with hole, and cloaking structure. Parameters are as in Figs. 2 and 5, i.e., r1 =30 mm, r2 =60 mm, L=4 mm, a = √3 × L, w =0.4 mm, and W =1 mm. Credit: Bückmann T, Kadic M, Schittny R, Wegener M (2015) Mechanical cloak design by direct lattice transformation, Proc Natl Acad Sci USA 112(16):4930-4934. Researcher Tiemo Bückmann discussed the paper he and his colleagues published in Proceedings of the National Academy of Sciences, as well as the challenges they faced in developing their concept and conducting the resulting research. “The main challenge in devising our approach – that is, of directly transforming the lattice points of a 2D discrete lattice composed of a single constituent material while keeping the properties of the elements connecting the lattice unchanged – was actually to come up the concept and think about realizing it,” Bückmann tells Phys.org. “At first, we just used that concept as an example to illustrate the basic concepts of cloaking, since it was taking us quite some time to really think about realizing such a structure out of one material – but this then worked so nicely that it was surprising even to us.”Another issue: cloaking a void in an effective elastic material with respect to static uniaxial compression as an example of elastic–solid mechanics. “Our main problem here was, first of all, that the mathematical background for a material parameter transformation is extremely complex,” Bückmann notes. “This makes the design of such a cloak highly complex as well as extremely demanding on materials and their effective properties.” That said, the scientists found that these problems were all solved by their straightforward approach of simply transforming the lattice points rather than effective material properties. “This simplified the cloaking concept enormously, making it possible for us to create a cloak along these lines.” Direct lattice-transformation approach. (A) A hexagonal lattice with lattice constant a composed of identical Ohmic resistors with resistance R. The lumped resistors (upper half) can equivalently be replaced by double-trapezoidal conductive elements (lower half) with length L=a/√3 and widths w and W as defined in the magnifying glass. (B) The lattice points (black dots) of the lattice in A are subject to a coordinate transformation. To keep the resistors R identical, while locally changing the length from L to L’ and fixing w, the width W is changed to W’ as indicated in the magnifying glass. One can proceed equivalently in heat conduction, particle diffusion, electrostatics, and magnetostatics. For elastic solids in mechanics, the resistors can be replaced by linear Hooke’s springs. The width W in the corresponding microstructure is again adjusted to W’ to keep the Hooke’s spring constant D identical while changing the length from L to L’ and fixing w. Credit: Bückmann T, Kadic M, Schittny R, Wegener M (2015) Mechanical cloak design by direct lattice transformation, Proc Natl Acad Sci USA 112(16):4930-4934. Mechanical cloaks of invisibility—without complicated mathematics Explore further Calculated performance of a lattice-transformation cloak. Constant pressure is exerted from the left- and right-hand side in each case. We compare the response of a homogeneous reference lattice (first row), the same finite lattice with a hole of radius r1 in the middle (second row), and the elastic cloak with inner radius r1 and outer radius r2 (third row) designed by direct lattice transformation. The (von Mises) stress is shown in the left column, the x component of the strain at the lattice points in the middle column, and the y component of the strain at the lattice points in the right column. We use a highly saturated false-color representation to exhibit all data on the same scale. The metamaterial structures (cf. Fig. 1) are shown underneath. The corresponding average relative error Δ of the strain vectors outside the cloak (i.e., for radii r >r2) with respect to the reference case is given on the right-hand side. The hole in the reference leads to large strains at the inner radius as well as outside of the cloak. Both aspects are dramatically improved by the cloak, Δ decreases by a factor of 34 from 738% to 22%. Parameters are: r1 =30mm, r2 =60mm, L=4 mm, a= √3 × L, w =0.4mm, and W =1mm. Credit: Bückmann T, Kadic M, Schittny R, Wegener M (2015) Mechanical cloak design by direct lattice transformation, Proc Natl Acad Sci USA 112(16):4930-4934. , Nature Communications Metamaterials – engineered materials with properties not found in nature – have led to an astounding range of optical, acoustic, thermodynamic, two-dimensional solid mechanics, and other types of invisibility cloaks that render the cloaked object indistinguishable from the environment around them – but the ability to cloak three-dimensional solid mechanics has proven elusive. (Solid mechanics is the branch of continuum mechanics – which models materials as a continuous mass rather than as discrete particles – that studies the behavior of solid materials, especially their motion and deformation under the action of forces, temperature changes, phase changes, and other external or internal agents.) Recently, however, scientists at Karlsruhe Institute of Technology, Germany – following their design last year of a so-called unfeelability cloak1 that hides (at this point small) 3D objects such that they cannot be physically detected – have demonstrated a surprisingly simple and generalizable approach in which a coordinate transformation – a mathematical process of obtaining a modified set of coordinates by performing some nonsingular operation on the coordinate axes, such as rotating or translating them – is mapped directly onto a concrete one-component microstructure. In addition, the researchers have successfully applied the technique to static elastic–solid mechanics (the elastic and plastic behavior of solid objects subject to stresses and strains) to a material made of printed polymer. In showing that the approach works in various areas, the researchers evaluated the main concepts of cloaking based on a lattice material, considering only static measurements. “Within these fields, Bückmann notes, “one can cloak in general any kind of physical problem that is linked to the same equations. A few examples in addition to mechanics, as presented in our paper,” he illustrates, “are current conduction, heat conduction, electrostatic potential, magnetostatics, and diffusion.” To underscore the effectiveness of their approach, Bückmann points out that while there were slight differences in the areas tested, in general – depending on the transformation and the given loading conditions – all simulations performed showed a relevant improvement over the case prior to our applying our transformation. “As one tries to cloak a larger and larger hole, or void, in a very thin cloaking shell,” he explains, “the performance of course decreases.” A third obstacle was comparing the average relative standard deviation of the strain vectors outside of the cloaked void with respect to the homogeneous reference lattice as a way of quantifying cloaking quality. “We thought about a way of quantifying the performance of our cloak, and so searched for a good quantity that is actually sensitive and, at the same time, representative for the performance of a cloak. We came up with the differences as a standard deviation between two samples.”Bückmann tells Phys.org that two insights were key to addressing these challenges. “First of all, we found the general concept of a lattice transformation cloak, which is applicable to many different physical quantities. Furthermore, we discovered that the concept also works in mechanics – one of the most demanding fields of physics with regard to cloaking.” This general concept is easy to understand, he points out, and therefore will hopefully help design a range of structures and solve problems in mechanical and engineering science.
Citation: Fruit fly brains found to have a ring of cells that work as a compass (2017, May 5) retrieved 18 August 2019 from https://phys.org/news/2017-05-fruit-brains-cells-compass.html Journal information: Science 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 Explore further © 2017 Phys.org Image: Sliver of Saturn (Phys.org)—A team of researchers with the Howard Hughes Medical Institute has found that a ring of cells in the middle of the fruit fly brain acts as a compass, helping the insect understand where it is, where it has been and where it is going. In their paper published in the journal Science, the team explains how they expanded on research they began two years ago and what their findings may mean for mammal internal navigation. Play A network of neurons in the fly brain acts as the fly’s internal compass. This study uses optogenetics and imaging of calcium activity in these neurons to show how this network of neurons maintains a unique internal representation of the fly’s heading. Credit: S.S. Kim et al., Igor Siwanowicz (title photograph), Bryan W. Jones (setup photograph), and Emily Nielson (video edit) As the researchers point out, their study offers evidence of the purpose of the neural ring, but does not explain how its nerves are activated, or how the fly receives information from the ring and uses it as a navigational aid. They plan to continue their research to see if they can find answers to such questions. 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. Credit: CC0 Public Domain More information: Sung Soo Kim et al. Ring attractor dynamics in the Drosophila central brain, Science (2017). DOI: 10.1126/science.aal4835AbstractRing attractors are a class of recurrent networks hypothesized to underlie the representation of heading direction. Such network structures, schematized as a ring of neurons whose connectivity depends on their heading preferences, can sustain a bump-like activity pattern whose location can be updated by continuous shifts along either turn direction. We recently reported that a population of fly neurons represents the animal’s heading via bump-like activity dynamics. We combined two-photon calcium imaging in head-fixed flying flies with optogenetics to overwrite the existing population representation with an artificial one, which was then maintained by the circuit with naturalistic dynamics. A network with local excitation and global inhibition enforces this unique and persistent heading representation. Ring attractor networks have long been invoked in theoretical work; our study provides physiological evidence of their existence and functional architecture. As the researchers note, two years ago, they discovered a group of approximately 50 neurons forming a ring in the center of the fruit fly brain that appeared to serve a navigational purpose. Since that time, they have studied how the ring might help the tiny insects make their way around in their environment.To find out, the researchers affixed fruit flies to a metal rod that held them in place and then played virtual reality scenes around them, simulating movement in their natural environment. As a fly moved its wings attempting to fly in the simulated surroundings, the researchers recorded neural activity in the ring. They found that individual clusters in the ring would fire corresponding to the direction in which the fly was trying to move.The researchers then genetically modified some of the neurons in the ring to activate when exposed to light. This allowed the team to manipulate the information the fly was receiving regarding its flight path. Firing light at the cells caused the fly to lose track of itself in its surroundings, strongly suggesting that the team was correct in their belief that the neural ring was similar to a compass. The team also ran similar experiments in which the flies were induced to fly in the dark, and found that though the fly appeared disoriented, it was not clear if it was due to interference by the team or just poor navigational skills in the dark in general.
The level of investments in domestic shares through participatory notes (P-Notes) declined to Rs 2.5 lakh crore ($39 billion) in November after hitting nearly a 7-year high in the preceding month.According to the data released by the Securities and Exchange Board of India (Sebi), the total value of P-Note investments in Indian markets (equity, debt and derivatives) dropped to Rs 2,49,210 crore last month from Rs 2,65,675 crore ($43 billion) in October. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cashInvestment in October was the highest level since February 2008, when the cumulative value of such investments stood at Rs 3,22,743 crore.P-Notes allow foreign investors to enter markets through registered foreign institutional investors (FIIs) and exempts them from getting registered directly with Sebi. This saves time and costs for investors, but the flip side is that the route can also be used for round tripping of black money.The quantum of foreign institutional investors’ (FII) investments through P-Notes dropped to 11 per cent last month from 12.2 per cent in October. Also Read – Lanka launches ambitious tourism programme to woo Indian touristsTill a few years ago, P-Notes used to account for more than 50 per cent of the total FII investments, but their share has fallen after Sebi tightened the disclosure norms and other regulations for such investments.P-Notes have been accounting for mostly 15-20 per cent of the total FII holdings in India since 2009, while it used to be much higher — in the range of 25-40 per cent — in 2008.It was as high as over 50 per cent at the peak of Indian stock market bull run during 2007.Last month, Sebi directed foreign investors to ensure compliance with all necessary norms before issuing such notes with immediate effect amid concerns about possible misuse of Offshore Derivative Instruments, or P-Notes, for money laundering and other such purposes.
Suspected Lashkar-e-Taiba (LeT) terrorist Abu Jundal, an alleged mastermind of the 26/11 Mumbai attacks, on Thursday told a Delhi court he should be shifted to the national Capital on completion of trial in an ongoing case in the western metropolis and the case should not be conducted through video-conferencing to enable him consult his lawyer.Jundal, alias Sayed Zabiuddin Ansari, who is lodged in Mumbai’s Arthur Road Jail, was produced before the court in the city through video-conferencing, where he requested the judge that he be shifted to Delhi for proceedings in the case pending in the national Capital. He told District Judge Amar Nath that since trial in the 2006 Aurangabad arms haul case in Mumbai, in which he is also an accused, was nearing an end and he should be brought to Delhi after that so that he can consult his counsel MS Khan. Also Read – Punjab on alert after release of excess water from Bhakra damThe court had last month allowed a plea of the NIA, seeking to conduct the proceedings in the case through video-conferencing after the agency apprehended threat to Jundal’s life. The proceedings in the case, in which NIA had chargesheeted Jundal for allegedly conspiring to carry out terror activities in India, have been stalled since May 2013 as Jundal was not produced before the court in the city.
Kolkata: The state Finance Minister Amit Mitra has been given the charge of the E-Governance department.At the same time, Chandrima Bhattacharya, who was Minister of State (Independent Charge) of E-Governance, has been made the Minister of State (Independent Charge) of the department of Planning and Statistics. Asima Patra has been given the charge of Minister of State (Independent Charge) of the department of Programme Monitoring. At present, Mitra is holding the portfolio of the state Finance minister, department of Industry, Commerce and Enterprises, department of Micro, Small and Medium Enterprises and Textiles and department of Information Technology and Electronics. With a notification issued on Friday, Mitra will also be looking after the E-Governance department. Also Read – Rain batters Kolkata, cripples normal lifeThe Mamata Banerjee government has taken a series of steps to ensure e-governance in the state. Almost all departments have been brought under the purview of e-governance and stress was given on e-transactions. It may be recalled that Mitra was given the charge of the Information Technology and Electronics department on October 4. It may be mentioned that earlier, the Personnel and Administrative Reforms and E-Governance departments were together. Now, the E-Governance department has been separated from the Personnel and Administrative Reforms department. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedSimilarly, Planning, Statistics and Programme Monitoring were together under one department. Whereas now, Programme Monitoring is a separate department, with Asima Patra as its Minister of State with Independent Charge. Chandrima Bhattacharya is the Minister of State with Independent Charge of the department of Planning and Statistics. Bhattacharya will also continue as the Minister of State for the state Health department, department of Land and Land Reforms and Refugee relief and Rehabilitation and department of Tribal Development. Meanwhile, Patra will continue as Minister of State for Backward Classes Welfare department, department of Agriculture and department of Fisheries.
Considered a complex hue by many, ultra violet holds loads of potential to jazz up any boring look with the utmost panache. Be it with ethnic styles or with the western look, experimenting with this vibrant colour will make the feminine beauty stand out and create a powerful statement amidst the blacks, reds and whites. The market offers many versatile shades and hues of ultra violet that can easily make their way into the wardrobe and jewellery box, whether in dresses, maxis, ethnic suits, saris or necklaces and jewellery pieces. Also Read – Add new books to your shelfExperts share tips on how to be stylish with trendy colour of 20184Pleated long skirts: Ultra violet pleated long skirts paired with a dull golden choli or a black shirt looks uber elegant and is a perfect option to stand out in the crowd. To add on one can carry a gemstone pendant or silver collar clips of similar shades.4Stripy jumpsuits: Jumpsuits of ultra violet hues striped with black, white, grey or blue will give your outfit a bold look and add that pop which may be missing earlier. Broad stripes, pinstripes, banker stripes are styles to mention a few. To accessorise with them, try the long and sleek danglers with a silver oxidized peppy nose pin. Also Read – Over 2 hours screen time daily will make your kids impulsive4Fringe fever: Fringes are the trend going in all lengths and styles, so whether opting for a fringe overlay or going for the tasselled hems the ultra violet hue as the base will surely add that extra grace to your look in 2018. With ultra violet as the main attraction, silver or platinum pastel coloured thread tassel earrings will complement the look well and will add that alluring charm.4Velvet wonder: Violet is one colour that looks stunning in velvet. Be it in the weddings or the cocktail parties, velvet suits, lehengas, and dresses look trendy and distinctly royal at the same time. An ultra violet velvet outfit with heavy embellishment will work tremendously. Go for a top-to-bottom violet look and break it with gold accessories.4Flared solid trousers: The much hyped 1970s flared solid colour trousers look is again in trend, and this time with even more glamorous allure. A fitted high waist ultra violet trouser with kick flares fastened with a button and zip are perfect.