Latest Posts by ritasakano - Page 8
Delicada sempre.
Textile sample. Japanese, Late Edo or early Meiji era, 19th century. Textile sample with design of carnations and lily-like flowers in white, reddish-orange, dark blue, yellow, grays, and light yellow browns on a blue ground, created by the yûzen process. Provenance: William Sturgis Bigelow Collection; gift of William Sturgis Bigelow to the MFA in August, 1898. MFA
Muitas vezes as imagens nos leva a mundos internos.
by Hisanori Manabe
(Image caption: Motor neurons (green) form synapses (highlighted in magenta) on muscle fibers in a fruit fly. MIT neuroscientists have discovered a pathway that contributes to strengthening these synapses. Credit: Troy Littleton)
Neuroscientists reveal how the brain can enhance connections
When the brain forms memories or learns a new task, it encodes the new information by tuning connections between neurons. MIT neuroscientists have discovered a novel mechanism that contributes to the strengthening of these connections, also called synapses.
At each synapse, a presynaptic neuron sends chemical signals to one or more postsynaptic receiving cells. In most previous studies of how these connections evolve, scientists have focused on the role of the postsynaptic neurons. However, the MIT team has found that presynaptic neurons also influence connection strength.
“This mechanism that we’ve uncovered on the presynaptic side adds to a toolkit that we have for understanding how synapses can change,” says Troy Littleton, a professor in the departments of Biology and Brain and Cognitive Sciences at MIT, a member of MIT’s Picower Institute for Learning and Memory, and the senior author of the study, which appears in the Nov. 18 issue of Neuron.
Learning more about how synapses change their connections could help scientists better understand neurodevelopmental disorders such as autism, since many of the genetic alterations linked to autism are found in genes that code for synaptic proteins.
Richard Cho, a research scientist at the Picower Institute, is the paper’s lead author.
Rewiring the brain
One of the biggest questions in the field of neuroscience is how the brain rewires itself in response to changing behavioral conditions — an ability known as plasticity. This is particularly important during early development but continues throughout life as the brain learns and forms new memories.
Over the past 30 years, scientists have found that strong input to a postsynaptic cell causes it to traffic more receptors for neurotransmitters to its surface, amplifying the signal it receives from the presynaptic cell. This phenomenon, known as long-term potentiation (LTP), occurs following persistent, high-frequency stimulation of the synapse. Long-term depression (LTD), a weakening of the postsynaptic response caused by very low-frequency stimulation, can occur when these receptors are removed.
Scientists have focused less on the presynaptic neuron’s role in plasticity, in part because it is more difficult to study, Littleton says.
His lab has spent several years working out the mechanism for how presynaptic cells release neurotransmitter in response to spikes of electrical activity known as action potentials. When the presynaptic neuron registers an influx of calcium ions, carrying the electrical surge of the action potential, vesicles that store neurotransmitters fuse to the cell’s membrane and spill their contents outside the cell, where they bind to receptors on the postsynaptic neuron.
The presynaptic neuron also releases neurotransmitter in the absence of action potentials, in a process called spontaneous release. These “minis” have previously been thought to represent noise occurring in the brain. However, Littleton and Cho found that minis could be regulated to drive synaptic structural plasticity.
To investigate how synapses are strengthened, Littleton and Cho studied a type of synapse known as neuromuscular junctions, in fruit flies. The researchers stimulated the presynaptic neurons with a rapid series of action potentials over a short period of time. As expected, these cells released neurotransmitter synchronously with action potentials. However, to their surprise, the researchers found that mini events were greatly enhanced well after the electrical stimulation had ended.
“Every synapse in the brain is releasing these mini events, but people have largely ignored them because they only induce a very small amount of activity in the postsynaptic cell,” Littleton says. “When we gave a strong activity pulse to these neurons, these mini events, which are normally very low-frequency, suddenly ramped up and they stayed elevated for several minutes before going down.”
Synaptic growth
The enhancement of minis appears to provoke the postsynaptic neuron to release a signaling factor, still unidentified, that goes back to the presynaptic cell and activates an enzyme called PKA. This enzyme interacts with a vesicle protein called complexin, which normally acts as a brake, clamping vesicles to prevent release neurotransmitter until it’s needed. Stimulation by PKA modifies complexin so that it releases its grip on the neurotransmitter vesicles, producing mini events.
When these small packets of neurotransmitter are released at elevated rates, they help stimulate growth of new connections, known as boutons, between the presynaptic and postsynaptic neurons. This makes the postsynaptic neuron even more responsive to any future communication from the presynaptic neuron.
“Typically you have 70 or so of these boutons per cell, but if you stimulate the presynaptic cell you can grow new boutons very acutely. It will double the number of synapses that are formed,” Littleton says.
The researchers observed this process throughout the flies’ larval development, which lasts three to five days. However, Littleton and Cho demonstrated that acute changes in synaptic function could also lead to synaptic structural plasticity during development.
“Machinery in the presynaptic terminal can be modified in a very acute manner to drive certain forms of plasticity, which could be really important not only in development, but also in more mature states where synaptic changes can occur during behavioral processes like learning and memory,” Cho says.
The study is significant because it is among the first to reveal how presynaptic neurons contribute to plasticity, says Maria Bykhovskaia, a professor of neurology at Wayne State University School of Medicine who was not involved in the research.
“It was known that the growth of neural connections was determined by activity, but specifically what was going on was not very clear,” Bykhovskaia says. “They beautifully used Drosophila to determine the molecular pathway.”
Littleton’s lab is now trying to figure out more of the mechanistic details of how complexin controls vesicle release.
Interessante!!!
Everyone pitches in for protein synthesis! Here are three types of RNA helping your cells make proteins. Be sure to check out all our science GIFs here for your studyblrs, teacher websites, presentations, or general amusement! Just please keep our name on there and don’t sell them! :D
Pervasive Pollution: Nurdles (Part 1)
Meet the Nurdles. They may be tiny, cute, and look like a bunch of cartoon characters, but don’t be fooled: these little guys are plotting ocean domination.
Nurdles are some of the planet’s most pervasive pollutants, found in lakes, rivers, and oceans across the globe. The tiny factory-made pellets form the raw material for every plastic product we use, and each year, billions of pounds of nurdles are produced, melted, and molded into toys, bottles, buttons, bags, pens, shoes, toothbrushes, and beads. They. Are. Everywhere.
But their real advantage in the quest for ocean domination is their incredible endurance—which allows them to persist in an environment for generations, because their artificial makeup makes them unable to biodegrade.
So, just as long as they don’t get into the environment, we have nothing to worry about, right?
The problem is, nurdles have a crafty way of doing exactly this. Produced in several countries, and shipped to plastics manufacturing plants the world over, nurdles often escape during the production process, carried by run-off to the coast, or during shipping when they’re mistakenly tipped into the waves.
And that’s just the beginning. Look out for more on these pervasive pollutants later this week, or check out the TED-Ed Lesson The nurdles’ quest for ocean domination - Kim Preshoff
Animation by Reflective Films
Five Fun Facts for the 2015 Geminid Meteor Shower
The Geminid meteor shower peaks this weekend starting on Sunday, Dec. 13. Here are a few fun facts:
Fact #1:
The Geminid meteor shower can be seen from both the Northern and Southern hemispheres. Because they are pieces of an asteroid, Geminid meteoroids can penetrate deeper into Earth’s atmosphere than most other meteor showers, creating beautiful long arcs viewable for 1-2 seconds.
Fact #2:
Geminids are pieces of debris from an object called 3200 Phaethon. It was long thought to be an asteroid, but is now classified as an extinct comet.
Phaethon’s eccentric orbit around the sun brings it well inside the orbit of Mercury every 1.4 years. Traveling this close to the sun blasts Phaethon with solar heat that may boil jets of dust into the Geminid stream. Of all the debris streams Earth passes through each year, the Geminid shower is the most massive. When we add up the amount of dust in this stream, it outweighs other streams by factors of 5 to 500.
Fact #3:
Because they are usually bright, many people say Geminid meteors show color. In addition to glowing white, they have been described as appearing yellow, green, or blue.
Geminid meteoroids hit earth’s atmosphere traveling 78,000 mph or 35 km/s. That may sound fast, but it is actually somewhat slow compared to other meteor showers.
Fact #4:
Geminids are named because the meteors seem to radiate from the constellation of Gemini. The shower lasts a couple of weeks, with meteors typically seen Dec. 4-17, peaking near Dec 13-14.
Fact #5:
The Geminids started out as a relatively weak meteor shower when first discovered in the early 19th century. Over time, it has grown into the strongest annual shower, with theoretical rates above 120 meteors per hour.
Join In:
This Sunday, Dec. 13, our Marshall Space Flight Center in Huntsville, Alabama, will host a live tweet chat highlighting the 2015 Geminid meteor shower. This online, social event will occur 11 p.m. EST Dec. 13, until 3 a.m. EST on Dec. 14. To join the conversation and ask questions, use #askNASA or @NASA_Marshall.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
Do not go where the path may lead, go instead where there is no path and leave a trail. —Ralph Waldo Emerson
Chopin, Bach used human speech ‘cues’ to express emotion in music
Music has long been described, anecdotally, as a universal language.
This may not be entirely true, but we’re one step closer to understanding why humans are so deeply affected by certain melodies and modes.
A team of McMaster researchers has discovered that renowned European composers Frédéric Chopin and Johann Sebastian Bach used everyday speech “cues” to convey emotion in some of their most famous compositions. Their findings were recently published in Frontiers of Psychology: Cognition.
Their research stemmed from an interest in human speech perception — the notion that “happy speech” for humans tends to be higher in pitch and faster in timing, while “sad speech” is lower and slower.
These same patterns are reflected in the delicate nuances of Chopin and Bach’s music, the McMaster team found.
To borrow from Canadian singer-songwriter Feist, we “feel it all” because the music features a very familiar cadence or rhythmic flow. It’s speaking to us in a language we understand.
“If you ask people why they listen to music, more often than not, they’ll talk about a strong emotional connection,” says Michael Schutz, director of McMaster’s MAPLE (Music, Acoustics, Perception & LEarning) Lab, and an associate professor of music cognition and percussion.
“What we found was, I believe, new evidence that individual composers tend to use cues in their music paralleling the use of these cues in emotional speech.” For example, major key or “happy” pieces are higher and faster than minor key or “sad” pieces.
The team also discovered that Bach and Chopin appear to “trade-off” their use of cues within the examined music.
Sets with larger pitch differences between major and minor key pieces had smaller timing differences, and vice versa. This may reflect efforts to balance the cues to avoid sounding trite, Schutz explains.
Schutz and Matthew Poon, a Music alumnus from the Class of 2012, began analyzing a complete body or “corpus” of three 24-piece sets by Chopin and Bach several years ago, as part of an Undergraduate Student Research Award (USRA) project. Poon is now a graduate student at the University of Toronto.
The pair analyzed all 48 preludes and fugues from J.S. Bach’s Well-Tempered Clavier (Book 1); as well as all 24 of Chopin’s Preludes (Op. 28). The pieces were chosen based on their historical significance and enduring popularity amongst performers, educators and audiences.
In order to ensure the tonal areas of each composition stayed in their stated keys, analysis was confined to the first eight complete measures — excluding pick-ups — from each of the 72 pieces.
Previous research on musical emotion has often involved manipulating existing melodies and compositions, Schutz explains. For example, transposing a melody higher or playing a song slower than written, in order to explore changes in emotional responses.
The McMaster-led study built upon that work by exploring how Bach and Chopin used emotional cues in their actual work — music still performed and enjoyed on a regular basis, hundreds of years after it was composed.
Can the same research be applied to modern pop music? Schutz says yes, although it’s much easier to analyze classical music based on the availability of sheet music and detailed notation, he offers.
Interessante!!
Sensation of Taste Is Built into Brain
Roast turkey. Stuffing. Mashed potatoes and gravy. Pie. Thanksgiving conjures up all sorts of flavors. If you close your eyes you can almost taste them. In fact, one day you may be able to—without food.
Scientists from Columbia University have figured out how to turn tastes on and off in the brain using optogenetics—a technique that uses penetrating light and genetic manipulation to turn brain cells on and off. They reported their findings in an article published in Nature. By manipulating brain cells in mice this way, the scientists were able to evoke different tastes without the food chemicals actually being present on the mice’s tongues.
The experiments “truly reconceptualize what we consider the sensory experience,” said Charles Zuker, head of the Zuker lab at Columbia and co-author on the paper. The results further demonstrate “that the sense of taste is hardwired in our brains,” Zuker said, unlike our sense of smell, which is strongly linked to taste but almost entirely dependent on experience.
Typically when we eat, the raised bumps, or papillae, that cover our tongues, pick up chemicals in foods and transmit tastes to the brain. There are five main types of papillae corresponding to each of the five basic tastes—sweet, sour, salty, bitter and umami. Contrary to popular belief, these aren’t clustered in particular places on the tongue, with bitter in the back and sweet at the front, but are spaced about evenly on the tongue.
A taste map may in fact exist, but it appears to be in the brain rather than on the tongue. First the researchers singled out the mice’s sweet and bitter taste centers in the brain, which are separated by approximately two millimeters in the insula. They concentrated on only sweet and bitter because the two are the most distinct from each other and also the most salient for humans, mice and other animals due their evolutionary importance to survival. Sweet usually indicates the presence of nutrients, whereas bitter signals potential danger of poison.
Zuker and his team then optogenetically stimulated the areas with light and in a series of behavioral tests, were able to have the mice taste sweet or bitter with only plain water. When the researchers activated the sweet neurons, they observed behavior consistent what with happens when mice normally encounter sweet foods: their licking increased significantly, even when the animals’ thirst was satiated. When the scientists stimulated neurons associated with bitter flavors, the mice stopped licking, seemed to scrub at their tongues and even gagged, depending on the level of optogenetic stimulation.
The researchers then performed the tests on animals that had never tasted sweet or bitter in their lives and found the same results. In the last set of experiments the researchers applied to the tongue of the mice chemicals that tasted sweet and bitter and compared their reactions to what happened when they simply stimulated the corresponding neurons optogenetically. There was no difference in the way the animals responded, “proving taste is hardwired in the brain,” Zuker said.
This doesn’t mean that there is no such thing as an “acquired taste,” Zuker clarified. For example, hákarl, fermented shark meat and national dish of Iceland, once called “the single worst, most disgusting and terrible tasting thing,” by famously acerbic food critic Anthony Bourdain is relished by many on the Nordic island nation. Humans are more complicated than mice. Taste can also be shaped by experience and culture. But the basics of this sensation are present from the beginning.
“Every baby smiles to sweet and frowns for bitter,” Zuker explained. “Taste mostly retains that hardwired response unless there is something that supersedes it. There are some things we consume [that] are innately aversive. But we take the gain with the bad if they have a positively reinforcing result.” Coffee or alcohol, for instance, are distinctly bitter, but many people learn to enjoy them over time due to the feelings of stimulation and inebriation they bring, respectively.
Gary Beauchamp, president of the Monell Chemical Senses Center in Pennsylvania, calls the research “a very clear and elegant approach,” confirming the long-standing hypothesis that taste is indeed evolutionarily hardwired. But Beauchamp also notes that sweet and bitter compounds can influence each other in the mouth to affect taste before they reach the brain. “In the real world, where foods are mixtures of things, it’s much more complex than what this study would suggest. Nevertheless, this is excellent work showing that these pathways are innately organized,” he said.
Zuker is aware that sweet and bitter are at the extremes of the taste spectrum and may not be representative of all tastes. But he expects similar results testing other tastes, which are also evolutionarily based. Salt, for example, signals electrolytes. “The next question is how activity in these cortical fields integrates with rest of brain,” to form experience and lasting taste memories – such as those we make at Thanksgiving.
Source: Scientific American
Como a linha que percorre a trama do tecido vejo-me envolvida pelos sentimentos diversos que ora aquece os ossos, ora os faz ficar doloridos.
Empodere as mulheres!!
Como as pessoas a nossa volta nos marcam. Interessante o uso de cores, uma vez que a energia que nos envolve tem amplitudes diferentes, portanto podemos representá-la pelo expectro de cores.
A cor de novembo
Novembro Marrom A cor da Terra A cor das lágrimas De um povo Calado Pela Lama.
Carbon and Our Changing Climate
Carbon is the backbone of life on Earth. We are made of carbon, we eat carbon and our civilizations are built on carbon. We need carbon, but that need is also entwined with one of the most serious problems facing us today: global climate change.
Forged in the heart of aging stars, carbon is the fourth most abundant element in the Universe. Most of Earth’s carbon – about 65,500 billion metric tons – is stored in rocks. The rest is in the ocean, atmosphere, plants, soil and fossil fuels.
Over the long term, the carbon cycle seems to maintain a balance that prevents all of Earth’s carbon from entering the atmosphere, or from being stored entirely in rocks. This balance helps keep Earth’s temperature relatively stable, like a thermostat.
Today, changes in the carbon cycle are happening because of people. We disrupt the cycle by burning fossil fuels and clearing land. Our Orbiting Carbon Observatory-2 (OCO-2) satellite is providing our first detailed, global measurements of CO2 in the atmosphere at the Earth’s surface. OCO-2 recently released its first full year of data, critical to analyzing the annual CO2 concentrations in the atmosphere.
The above animation shows carbon dioxide released from two different sources: fires and massive urban centers known as megacities. The animation covers a five day period in June 2006. The model is based on real emission data and is then set to run so that scientists can observe how greenhouse gas behaves once it has been emitted.
All of this extra carbon needs to go somewhere. So far, land plants and the ocean have taken up about 55 percent of the extra carbon people have put into the atmosphere while about 45 percent has stayed in the atmosphere. The below animation shows the average 12-month cycle of all plant life on Earth (on land and in the ocean). Eventually, the land and oceans will take up most of the extra carbon dioxide, but as much as 20 percent may remain in the atmosphere for many thousands of years.
Excess carbon in the atmosphere warms the planet and helps plants on land grow more. Excess carbon in the ocean makes the water more acidic, putting marine life in danger. Forest and other land ecosystems are also changing in response to a warmer world. Some ecosystems – such as thawing permafrost in the Arctic and fire-prone forests – could begin emitting more carbon than they currently absorb.
To learn more about NASA’s efforts to better understand the carbon and climate challenge, visit: http://www.nasa.gov/carbonclimate/.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
Outro crime ambiental no Brasil. E quem continua a sofrer é a população.
Quando vejo esta linda arte meu coração e razão se enfurece com os professores, pois um dia falaram que os povos africanos não tinham arte e nem história.
Ethiopian magic scrolls.
1. Magic scroll, Ethiopia, Late 19th century
2. Magic scroll, Ethiopia Early 19th century, 2180 x 180 mm
3- Magic scroll of Wälättä-Gabriel, Ethiopia, 19th century
Solar System: 5 Things to Know This Week
Our solar system is huge, so let us break it down for you. Here are 5 things to know this week:
1. It’s Lunacy, Whether by Day or Night
What’s Up in the night sky during November? See all the phases of the moon by day and by night, and learn how to look for the Apollo landing sites. Just after sunset on November 13 and 14, look near the setting sun in the western sky to see the moon as a slender crescent. For more, catch the latest edition of the monthly “What’s Up” Tumblr breakdown.
2. Answer to Longstanding Mars Mystery is Blowin’ in the Wind
What transformed Mars from a warm and wet environment, one that might have supported surface life, to the cold, arid planet it is today? Data from our Mars Atmosphere and Volatile Evolution (MAVEN) mission pins much of the blame on the sun. Streams of charged solar particles crash against the Martian atmosphere, and without much of a magnetic field there to deflect the onslaught, over time the solar wind has stripped the air away.
3. Orbital Maneuvers in the Dark
The New Horizons mission team has set a new record. They recently performed the last in a series of trajectory changes that set the spacecraft on a course for an encounter with a Kuiper Belt object in January 2019. The Kuiper Belt consists of small bodies that orbit the sun a billion miles or more beyond Pluto. These latest course maneuvers were the most distant trajectory corrections ever performed by any spacecraft.
4. Visit Venus (But Not Really — You’d Fry)
Mars isn’t the only available destination. You can visit all the planets, moons and small worlds of the solar system anytime, right from your computer or handheld device. Just peruse our planets page, where you’ll find everything from basic facts about each body to the latest pictures and discoveries. Visit Venus HERE.
5. Titan Then and Now
Nov. 12 marks the 35th anniversary of Voyager 1’s Saturn flyby in 1980. Voyager saw Saturn’s enshrouded, planet-sized moon Titan as a featureless ball. In recent years, the Cassini mission haas revealed Titan in detail as a complex world. The spacecraft has peered beneath its clouds, and even delivered a probe to its encounter, which will include infrared scans, as well as using visible light cameras to look for methane clouds in the atmosphere.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
Mohommah G. Baquaqua
“’Que aqueles ‘indivíduos humanitários’ que são a favor da escravidão se coloquem no lugar do escravo no porão barulhento de um navio negreiro, apenas por uma viagem da África à América, sem sequer experimentar mais que isso dos horrores da escravidão: se não saírem abolicionistas convictos, então não tenho mais nada a dizer a favor da abolição.’ As palavras são de Mahommah Gardo Baquaqua, ex-escravo nascido no Norte da África no início do século XIX e que trabalhou no Brasil antes de fugir das amarras da servidão em Nova York, em 1847. O trecho consta do livro “An interesting narrative. Biography of Mahommah G. Baquaqua” (“Uma interessante narrativa: biografia de Mahommah G. Baquaqua”, em tradução livre), lançado assim mesmo, em inglês, pelo próprio ex-escravo, em Detroit, no ano de 1854, em plena campanha abolicionista nos EUA. A obra jamais foi traduzida para o português, permanecendo desconhecida do público brasileiro.
Fonte: http://www.bocadaforte.com.br/reportagens/baquaqua-a-auto-biografia-de-um-escravo.html
Peça lindamente bordada.
Outer kimono (uchikake), satin silk with appliqué and embroidery, 1870–90. Scenes from two well-known plays feature. The garment may have been worn by a Kabuki actor, but decorative themes on stage costumes were not usually so literal and may instead have belonged to a high-ranking courtesan. The enjoyments of the theatre and the brothel were closely linked during the Edo period (1615 – 1868), being at the heart of the ‘floating world’ of transient excitement and pleasure.