ecological burns at jocassee gorges to restore habitat, improve safety many species and ecosystems require fire periodically to ensure their survival, and that ’ s why prescribed burns will again be a part of the s. c. department of natural resources ’ management of the jim timmerman natural resources area at jocassee gorges in 2008. " the objective of the controlled burns, which will likely begin in january, is to maintain the ecological integrity of these lands, " said mark hall, s. c. department of natural resources ( dnr ) wildlife biologist and forest planner, " and to provide for human safety by reducing the amount of fuel on the natural area, thereby reducing the chance of catastrophic wildfire. for many of these ecosystems, it ’ s not a matter of ' if ' they will burn, but rather ' when. ' we like to choose the ' when. ' " burning will be done when the weather is suitable to allow for a safe burn, including the rapid rising and dispersal of smoke, hall said. once weather conditions are right for the burn, it should take four to eight hours for the active burning to be completed, although scattered stumps, logs and dead trees may smolder slowly through the night. fires will be surrounded by fire breaks, which include existing preserve roads, streams, plowed fire breaks and breaks put in with hand tools in sensitive areas. " through the centuries, many native plants, animals and habitats in the southeastern united states have adapted to the presence of recurring fire, " hall said. " many species and ecosystems are now rare because of fire suppression, and they actually need fire to ensure their survival. we ’ ve burned more than 1, 500 acres in the last three years to help restore natural process in the system. " hall emphasized that since controlled burning requires careful timing and a thorough knowledge of weather and fire behavior, highly trained fire personnel with the dnr and s. c. forestry commission will manage and conduct all aspects of the controlled burns. " besides the ecological benefits of prescribed fire, it also has the added benefit of reducing fuel on the forest floor and lessening the chances of a catastrophic fire, which can threaten homes and people, " hall said. " because fire has been suppressed for so long in some places, you get dangerous buildups of fuel and increase the chances for a wildfire that can destroy property and lives. the wildfires we ’ ve seen across the united states in the last 15 years, due in large part to past fire suppression, underscore the need


buildups of fuel and increase the chances for a wildfire that can destroy property and lives. the wildfires we ’ ve seen across the united states in the last 15 years, due in large part to past fire suppression, underscore the need for prescribed fire. " by using a controlled burn — when wind, temperature and humidity conditions are appropriate to remove some of the forest fuel like leaves, pine needles and twigs — fire managers can greatly reduce the chances of a catastrophic wildfire. after controlled burns are completed, the homes and properties close to jocassee gorges will be much less likely to be in the path of a wildfire, because the fuel is reduced or eliminated. optimal weather conditions will be chosen for smoke dispersal, but hall advised that during these controlled burns nearby residents will certainly see and smell smoke. the smoke usually disappears by the end of the day. " people become upset when there is smoke in the air if they don ’ t know the reason for the fire, " hall said. " that ’ s why we ’ re trying to get the word out about prescribed fire. if we carefully plan and conduct a burn when weather conditions favor smoke dispersal, this reduces smoke - related problems. dealing with a little bit of smoke now is infinitely better than trying to control a raging wildfire later. " waterfalls, green salamanders, black bear, uncommon plants such as oconee bells and many long - range vistas are just a few of the natural wonders that may be found in the 33, 000 - acre jim timmerman natural resources area at jocassee gorges in pickens and oconee counties. more information on the jocassee gorges may be obtained by calling the clemson dnr office at ( 864 ) 654 - 1671, extension 22. dnr protects and manages south carolina ’ s natural resources by making wise and balanced decisions for the benefit of the state ’ s natural resources and its people.


exceptions are a means of breaking out of the normal flow of control of a code block in order to handle errors or other exceptional conditions. an exception is the python interpreter raises an exception when it detects a run - time error ( such as division by zero ). a python program can also explicitly raise an exception with the raise statement. exception handlers are specified with the try... except statement. the try... finally statement specifies cleanup code which does not handle the exception, but is executed whether an exception occurred or not in the preceding code. python uses the ` ` termination ' ' when an exception is not handled at all, the interpreter terminates execution of the program, or returns to its interactive main loop. in either case, it prints a stack backtrace, except when the exception is exceptions are identified by string objects or class instances. selection of a matching except clause is based on object identity ( i. e., two different string objects with the same value represent different exceptions! ) for string exceptions, the except clause must reference the same string object. for class exceptions, the except clause must reference the same class or a base class of it. when an exception is raised, an object ( maybe none ) is passed as the exception ' s ` ` parameter ' ' or ` ` value ' ' ; this object does not affect the selection of an exception handler, but is passed to the selected exception handler as additional information. for class exceptions, this object must be an instance of the exception class see also the description of the try statement in section 7. 4 and raise statement in section 6. 8.


reading this tutorial has probably reinforced your interest in using python - - you should be eager to apply python to solve your real - world problems. now what should you do? you should read, or at least page through, the python library reference, which gives complete ( though terse ) reference material about types, functions, and modules that can save you a lot of time when writing python programs. the standard python distribution includes a lot of code in both c and python ; there are modules to read unix mailboxes, retrieve documents via http, generate random numbers, parse command - line options, write cgi programs, compress data, and a lot more ; skimming through the library reference will give you an idea of what ' s available. the major python web site is http : / / www. python. org / ; it contains code, documentation, and pointers to python - related pages around the web. this web site is mirrored in various places around the world, such as europe, japan, and australia ; a mirror may be faster than the main site, depending on your geographical location. a more informal site is http : / / starship. python. net /, which contains a bunch of python - related personal home pages ; many people have downloadable software there. many more user - created python modules can be found in the python package index ( pypi ). for python - related questions and problem reports, you can post to the newsgroup comp. lang. python, or send them to the mailing list at firstname. lastname @ example. org. the newsgroup and mailing list are gatewayed, so messages posted to one will automatically be forwarded to the other. there are around 120 postings a day ( with peaks up to several hundred ), asking ( and answering ) questions, suggesting new features, and announcing new modules. before posting, be sure to check the list of frequently asked questions ( also called the faq ), or look for it in the misc / directory of the python source distribution. mailing list archives are available at http : / / www. python. org / pipermail /. the faq answers many of the questions that come up again and again, and may already contain the solution for your problem. see about this document... for information on suggesting changes.


the cerebrum, the largest part of the brain, is separated into the right and left hemispheres. the right hemisphere is in charge of the functions on the left - side of the body, as well as many cognitive functions. a right - side stroke happens when the brain ’ s blood supply is interrupted in this area. without oxygen and nutrients from blood, the brain tissue quickly dies. a stroke is a serious condition. it requires emergency care. there are two main types of stroke : an ischemic stroke ( the more common form ) is caused by a sudden decrease in blood flow to a region of the brain, which may be due to : - a clot that forms in another part of the body ( eg, heart or neck ) breaking off and blocking the flow in a blood vessel supplying the brain ( embolus ) - a clot that forms in an artery that supplies blood to the brain ( thrombus ) - a tear in an artery supplying blood to the brain ( arterial dissection ) a hemorrhagic stroke is caused by a burst blood vessel that results in bleeding in the brain. examples of risk factors that you can control or treat include : certain conditions, such as : - high blood pressure - high cholesterol - high levels of the amino acid homocysteine ( may result in the formation of blood clots ) - atherosclerosis ( narrowing of the arteries due to build - up of plaque ) - atrial fibrillation ( abnormal heart rhythm ) - metabolic syndrome - type 2 diabetes - alcohol or drug abuse - medicines ( eg, long - term use of birth control pills ) - lifestyle factors ( eg, smoking, physical inactivity, diet ) risk factors that you cannot control include : - history of having a stroke, heart attack, or other type of cardiovascular disease - history of having a transient ischemic attack ( tia ) — with a tia, stroke - like symptoms often resolve within minutes ( always in 24 hours ). they may signal a very high risk of having a stroke in the future. - age : 60 or older - family members who have had a stroke - gender : males - race : black, asian, hispanic - blood disorder that increases clotting - heart valve disease ( eg, mitral stenosis ) the immediate symptoms of a right - side stroke come on suddenly and may include : - weakness or numbness of face, arm, or leg, especially on the left side of the body - loss of balance


( eg, mitral stenosis ) the immediate symptoms of a right - side stroke come on suddenly and may include : - weakness or numbness of face, arm, or leg, especially on the left side of the body - loss of balance, coordination problems - vision problems, especially on the left - side of vision in both eyes - difficulty swallowing if you or someone you know has any of these symptoms, call 911 right away. a stroke needs to be treated as soon as possible. longer - lasting effects of the stroke may include problems with : - left - sided weakness and / or sensory problems - speaking and swallowing - vision ( eg, inability for the brain to take in information from the left visual field ) - perception and spatial relations - attention span, comprehension, problem solving, judgment - interactions with other people - activities of daily living ( eg, going to the bathroom ) - mental health ( eg, depression, frustration, impulsivity ) the doctor will make a diagnosis as quickly as possible. tests may include : - exam of nervous system - computed tomography ( ct ) scan — a type of x - ray that uses a computer to make pictures of the brain - ct angiogram — a type of ct scan which evaluates the blood vessels in the brain and / or neck - magnetic resonance imaging ( mri ) scan — a test that uses magnetic waves to make pictures of the brain - magnetic resonance angiography ( mra ) scan — a type of mri scan which evaluates the blood vessels in the brain and / or neck - angiogram — a test that uses a catheter ( tube ) and x - ray machine to assess the heart and its blood supply - heart function tests ( eg, electrocardiogram, echocardiogram ) - doppler ultrasound — a test that uses sound waves to examine the blood vessels - blood tests - tests to check the level of oxygen in the blood - kidney function tests - tests to evaluate the ability to swallow immediate treatment is needed to potentially : - dissolve a clot causing an ischemic stroke - stop the bleeding during a hemorrhagic stroke in some cases, oxygen therapy is needed. medicines may be given right away for an ischemic stroke to : - dissolve clots and prevent new ones from forming - thin blood - control blood pressure - reduce brain swelling - treat an irregular heart rate cholesterol medicines called statins may also be given. for a hemorrhagic stroke, the doctor may give medicines to : -


new ones from forming - thin blood - control blood pressure - reduce brain swelling - treat an irregular heart rate cholesterol medicines called statins may also be given. for a hemorrhagic stroke, the doctor may give medicines to : - work against any blood - thinning drugs that you may regularly take - reduce how your brain reacts to bleeding - control blood pressure - prevent seizures for an ischemic stroke, procedures may be done to : - reroute blood supply around a blocked artery - remove the clot or deliver clot - dissolving medicine ( embolectomy ) - remove fatty deposits from a carotid artery ( major arteries in the neck that lead to the brain ) ( carotid artery endarterectomy ) - widen carotid artery and add a mesh tube to keep it open ( angioplasty and stenting ) for a hemorrhagic stroke, the doctor may : - remove a piece of the skull ( craniotomy ) to relieve pressure on the brain and remove blood clot - place a clip on or a tiny coil in the aneurysm to stop it from bleeding a rehabilitation program focuses on : - physical therapy — to regain as much movement as possible - occupational therapy — to assist in everyday tasks and self - care - speech therapy — to improve swallowing and speech challenges - psychological therapy — to help adjust to life after the stroke to help reduce your chance of having a stroke, take the following steps : - exercise regularly. - eat a healthy diet that includes fruit, vegetables, whole grains, and fish. - maintain a healthy weight. - if you drink alcohol, drink only in moderation ( 1 - 2 drinks per day ). - if you smoke, quit. - if you have a chronic condition, like high blood pressure or diabetes, get proper treatment. - if recommended by your doctor, take a low - dose aspirin every day. - if you are at risk for having a stroke, talk to your doctor about taking statin medicines. - reviewer : rimas lukas, md - review date : 06 / 2012 - - update date : 00 / 61 / 2012 -


the thick durable sea ice that routinely cloaked much of the arctic ocean in colder decades in the 20th century is increasingly relegated to a few clotted places along northern canada and greenland, according to the latest satellite analysis of the warming region. the following video gives you a fascinating view of one patch of sea ice through 90 days, provided by a webcam left behind by researchers who annually set up camp near the north pole to check ocean and ice conditions up close. the new analysis, published in the journal of geophysical research on tuesday, is the latest of many findings supporting the idea that the region has shifted to a new state in which seasonal ice, which forms in winter and melts in the summer, dominates. this is the main reason biologists have concerns for the long - term welfare of polar bears, which have a harder time sustaining their weight and reproducing when summertime ice is thin. at the same time, the shift bodes well for shippers, like the german company beluga, that have plans to start sending goods from asia to northern europe through the fabled, but long impassible, northern sea route over russia. the study, conducted by scientists from nasa, the university of washington and the california institute of technology estimated changes from 2003 to 2008 in the total volume and thickness of what ’ s called multi - year ice, the yards - thick floes that can persist through a summer ( here ’ s some video i shot while standing on a mix of old and thinner ice in 2003 ), and seasonal ice, which can grow to 6 feet in thickness in winter but vanishes in summer. for a look at how this summer ’ s arctic sea - ice season may unfold, visit sea ice outlook 2009, where more than a dozen groups of ice researchers are posting experimental forecasts of how the ice is likely to fare. there ’ s a strong consensus that the season will see much less sea ice than the average for the period monitored by satellites ( from 1979 onward ), but is unlikely to see the extent of open water measured in 2007. to get a sense of how the views of arctic experts have coalesced around a rising human influence on the region ’ s climate, you can scan previous stories from 2001, 2005, and 2007 on ice trends and possible causes.


as a graduate student working for ligo ( the laser interferometer gravitational wave observatory ), one of my responsibilities was maintaining date - time code, including accounting for leap seconds, and calculating dates and time thousands of years in the past. what is a leap second? well, the earth ' s rotation rate is slowing down. so, as time goes on the length of the day is longer. this rate is very slow. every few years, the added length must be taken into account, much like the leap day takes into account that the orbital period of the earth around the sun is not exactly 365 days. when a leap second must be inserted is not predictable. the international earth rotation and reference systems service is tasked with making observations of the earth, and producing a twice - yearly report on whether a leap second is due to be added. this comes out by email, and on their website. the report gives a 6 - month or so lead time before the leap second is inserted, at midnight on jan 1 and on jul 1. so, apparently, a leap second was inserted last night : all standard atomic clocks around the world paused for a second. this caused all sorts of havoc with computers and networking devices, causing lots of sites to go down. notably, google was prepared.


richards, m. p. and schulting, r. j. and hedges, r. e. m. ( 2003 ) ' sharp shift in diet at onset of neolithic. ', nature., 425 ( 6956 ). p. 366. the introduction of domesticated plants and animals into britain during the neolithic cultural period between 5, 200 and 4, 500 years ago is viewed either as a rapid event1 or as a gradual process that lasted for more than a millennium2. here we measure stable carbon isotopes present in bone to investigate the dietary habits of britons over the neolithic period and the preceding 3, 800 years ( the mesolithic period ). we find that there was a rapid and complete change from a marine - to a terrestrial - based diet among both coastal and inland dwellers at the onset of the neolithic period, which coincided with the first appearance of domesticates. as well as arguing against a slow, gradual adoption of agriculture and animal husbandry by mesolithic societies, our results indicate that the attraction of the new farming lifestyle must have been strong enough to persuade even coastal dwellers to abandon their successful fishing practices. | full text : | | full text not available from this repository. | | publisher web site : | | http : / / dx. doi. org / 10. 1038 / 425366a | | record created : | | 07 apr 2009 | | last modified : | | 21 jul 2010 16 : 58 | | social bookmarking : | | export : endnote, zotero | bibtex | | usage statistics | | look up in googlescholar | find in a uk library |


a few weeks ago, i traveled to israel with my ten - year - old daughter sage, to participate in the olive harvest. this was my long - awaited opportunity to do hands - on research for a picture book i ’ m writing and illustrating about an ancient olive tree. i couldn ’ t wait to roll up my sleeves and get out in the olive grove. there ’ s something special about hands - on research. in this age of unprecedented convenience, we have the technological ability to access information from all over the world in a matter of seconds. but information obtained this way can lack authenticity, and often appears out of context. rarely do i have the opportunity to physically experience what i ’ m drawing or writing about. but there ’ s no substitute for direct experience when it comes to bringing a story to life. the morning after we arrived at kibbutz gezer, a half a dozen olive pickers gathered by the side of the road that encircles the kibbutz. inside the circle, the homes for approximately 400 people are clustered together. outside the circle are grassy meadows ; a baseball field ; swimming pool ; a field of eggplants ; a tel – an ancient town filled in over the centuries by debris until it becomes a flat - topped, man - made hill, now the site of an archeological excavation – and of course, the olive groves. hundreds of trees of approximately 30 years of age stood in grassy rows. most were heavy with fruit, their branches drooping under the weight of colorful clusters of olives. the harvest technique is simple : we spread black plastic tarps under the trees, and used small hand - held rakes to “ comb ” the olives from the branches. most of the fruit could be reached either from the ground or by climbing a few steps up the trunk. the trees are pruned to stay low, and the limbs are encouraged to spread out like a basket, so that every part of the tree receives maximum sunlight. it is said that if an olive tree is pruned properly, there ’ s enough space between the branches to allow a bird to fly through. olive trees are uniquely dependent upon humans for this pruning – they cannot thrive without it. an olive tree that is well - pruned can continue to regenerate from its roots virtually indefinitely, with a lifespan of two thousand years or even longer. thus the olive tree has been a symbol of renewal for millennia. olive fruits are firm and smooth, with a chalky skin that turns shiny when you rub


. and israel was retaliating with “ operation pillar of cloud ”, a targeted defensive operation that took place the week we were there. truly, israel is a land of paradox – of cultural, artistic and spiritual riches ; unparalleled innovations in education, medicine, agriculture, technology, and energy conservation – not to mention wonderful people – yet israel is also a troubled place, with internal rifts, economic problems, and seemingly - intractable conflicts with its arab neighbors. traveling in israel, it is not unusual to feel conflicting emotions. even as we worked in such a bucolic place as the olive grove, we were all aware of the location of the closest bomb shelter, which had been unlocked that week for rapid entry. and we all knew that beyond the “ green line ” ( the disputed border between israel and the west bank ), palestinians were harvesting olive trees just like ours. this is not the first century, or even the first millennium, in which olive trees have been implicated in matters of territorial conflict. for the olive tree is native to a region that is rife with inescapable complexities. rooted in a shifting tapestry of peoples and conquests, the olive tree stands constant as a living organism of renewal and peace. i loved the olive grove, and got into a groove with my yellow rake. the conversation was lively : there were kibbutz members who had come to help, along with dogs of all shapes and sizes. there were friends from jerusalem, a traveling post - grad student from the u. s., and visitors from norway. everyone was in good spirits as we gathered up the tarps and poured the fruit into crates. these would be taken to the olive press at nearby latroun. an olive press is a huge industrial machine that is necessarily communal ; no one can own their own olive press. at latroun, we saw jews and arabs alike waiting for the yield of their harvest, chatting in english, hebrew, and arabic as the olives were pressed, separated by centrifuge into pomace and oil, and finally decanted into containers. the leftover “ mash ” of fiber and pits is sometimes pressed into dry cakes to be burned as fuel – a great idea! hours after the picking was done, at the end of the day i returned to the olive grove to sketch. i did pencil drawings and brush drawings, trying to capture the shapes of the trees, the texture of the leaves. i tested a few colors, and tried to catch the


, at the end of the day i returned to the olive grove to sketch. i did pencil drawings and brush drawings, trying to capture the shapes of the trees, the texture of the leaves. i tested a few colors, and tried to catch the contour of the land. birds twittered from opposite sides of the grove, calling to each other. dogs barked in the distance as the sun went down, mingled with the sound of a child ’ s laughter. in the hush that followed, the peace of the olive grove was palpable. my daughter sat beside me with her own drawing book, both of us sitting on torn pieces of cardboard on the ground while we sketched. she drew a twisted olive trunk, then switched to fashion designs. i hope when she grows up, she ’ ll remember that day. in addition to the jug of fresh olive oil i brought home, i also harvested something else : photos, sketches, notes, and memories. these impressions from my week of picking olives will be gathered and pressed, spun and separated into the many components of a book. this book has taken its time to ripen and grow, but i hope in the end it will be worth it. the more i learn about olives, the more there is to know – from cultivation techniques to nutritional and medicinal benefits, from historical facts to political implications. and the more i learn about olives, the more i love them. special thanks to dani livney and all the wonderful folks at kibbutz gezer for making this trip possible. we hope to return next year to pick olives again! חג החנוכה שמח! we are about to celebrate chanukah, the festival of light that remembers each year the miracle of oil – olive oil – in a story that is rooted a mere bike ride ’ s distance from gezer. the maccabean graves in nearby modi ’ in is where the hasmoneans, who ruled a jewish dynasty in israel, have been buried in the ground for more than 2, 100 years. some of the olive trees that lived then are still alive today. happy holidays to all –


what is fracking? it ’ s not the latest teenage slang word ; it describes a mining process that is polluting our earth and making people sick. food & water watch explains : to frack an oil or gas well, a massive volume of water, sand, and chemicals is injected underground at high pressure to break up rock formations, allowing oil or gas to flow up the well. fracking threatens the air we breathe, the water we drink, the communities we love, and the climate on which we depend. mothers are rallying against this horrible practice! in fact, they are outraged the practice is considered for use around schools, let alone their homes. food & water watch explains and asks you to take action! mothers in the community of erie, colorado, are working desperately to stop a giant oil and gas company from fracking next to their kids ’ elementary school. they ’ ve asked encana, a giant oil and gas company, to abandon this one well and protect their children, but the company refuses. fracking is associated with increased truck traffic, dangerous chemicals as well as air and water contamination. it ’ s hard to believe encana would even consider fracking near an elementary school – worse, its hard to believe that regulatory systems in colorado have failed to prevent this from happening. and yet, encana has gone through all of the proper channels and has the green light to start fracking on may 26th. i have heard so many people express support of oil and shale gas mining on american soil who do not understand the issue of fracking. they believe the false job promises of domestic oil production not realizing how their very water and air are being dangerously contaminated. fracking is one of the biggest environmental crises facing this country! it ’ s poisoning our drinking water, even making it flammable! propublica explains : for the first time, a scientific study has linked natural gas drilling and hydraulic fracturing with a pattern of drinking water contamination so severe that some faucets can be lit on fire … “ this study provides eye - opening scientific evidence about methane contamination and the risks that irresponsible natural gas drilling poses for drinking water supplies, ” said congressman maurice hinchey, d - n. y. “ it provides yet another reason why more study of the environmental and health risks associated with hydraulic fracturing is needed. ” hinchey is one of several democratic members of congress who recently re - introduced the frac act, which calls for public disclosure of the chemicals used underground. the bill, which is currently


handbook of engaged learning projects subject / content area : science, language arts, math, and social target audience : this multigrade level unit will involve third and sixth grade students. this is an interactive, interdisciplinary, thematic project. this is appropriate for students at all ability levels. program requires hardware / software for internet access. project goal : when posed with the problem of destruction of the rainforest, students will develop interpersonal skills, research skills, content objectives, technical skills, and higher order thinking skills. learner outcomes : through cooperative activities, students will be able to : - demonstrate the ability to collect data using various technologies ( internet, cd rom, computer software / hardware, and e - mail ). - analyze the impact of specific human activities on the destruction of tropical rainforests. - organize and analyze collected information gained through interaction - explain the important biological, social, and aesthetic values of the tropical rainforest to their environment. alignment with standards ( national - science standards : 7, 15, 18 - language arts : 1, 3, 4, 5, 7, 9, 10, 11 - math : 4, 6 - geography : 1, 2, 4, 8, 14, 16, 18 assessment of students : students ' performance will be assessed formatively through teacher observations. students and teachers will cooperatively develop a rubric for the final product. summative evaluation will include self - evaluation and teacher evaluation. author : patti furlano, joyce nelson, teri rakes and amy willis, braceville elementary school, braceville, il. of engaged learning projects sponsored by fermi national accelerator laboratory education office and friends of fermilab. funded by the north central regional technology in education consortium based at the north central regional educational laboratory ( ncrel ). created : august, 1997


( cnn ) - - michael jackson was on to something when he sang that " a - b - c " is " simple as ' do re mi. ' " music helps kids remember basic facts such as the order of letters in the alphabet, partly because songs tap into fundamental systems in our brains that are sensitive to melody and beat. that ' s not all : when you play music, you are exercising your brain in a unique way. " i think there ' s enough evidence to say that musical experience, musical exposure, musical training, all of those things change your brain, " says dr. charles limb, associate professor of otolaryngology and head and neck surgery at johns hopkins university. " it allows you to think in a way that you used to not think, and it also trains a lot of other cognitive facilities that have nothing to do with music. " the connection between music and the brain is the subject of a symposium at the association for psychological science conference in chicago this weekend, featuring prominent scientists and grammy - winning bassist victor wooten. they will discuss the remarkable ways our brains enable us to appreciate, remember and play music, and how we can harness those abilities in new ways. there are more facets to the mind - music connection than there are notes in a major scale, but it ' s fascinating to zoom in on a few to see the extraordinary affects music can have on your brain. whether it ' s " somewhere over the rainbow " or " somebody that i used to know, " or even " bad romance " or " bohemian rhapsody, " it ' s easy to get part of a song stuck in your head, perhaps even a part that you don ' t particularly like. it plays over and over on repeat, as if the " loop " button got stuck on your music player. scientists think of these annoying sound segments as " ear worms. " they don ' t yet know much about why they happen, but research is making headway on what ' s going on. the songs that get stuck in people ' s heads tend to be melodically and rhythmically simple, says daniel levitin, a psychologist who studies the neuroscience of music at mcgill university in montreal, quebec. it ' s usually just a segment of the song, not the entire thing from beginning to end. a common method of getting rid of an ear worm is to listen to a different song - - except, of course, that song might plant itself in your thoughts for awhile. " what we think is going on is that the neural circuits


to end. a common method of getting rid of an ear worm is to listen to a different song - - except, of course, that song might plant itself in your thoughts for awhile. " what we think is going on is that the neural circuits get stuck in a repeating loop and they play this thing over and over again, " levitin said. in rare cases, ear worms can actually be detrimental to people ' s everyday functioning, levitin said. there are people who can ' t work, sleep or concentrate because of songs that won ' t leave their heads. they may even need to take the same anti - anxiety medications given to people with obsessive - compulsive disorder, drugs that relax the neural circuits that are stuck in an infinite loop. how we evolved to remember music given how easily song snippets get stuck in our heads, music must be linked to some sort of evolutionary adaptation that helped our ancestors. bone flutes have been dated to about 40, 000 to 80, 000 years ago, so people were at least playing music. experts assume that people were probably singing before they went to the trouble of fashioning this instrument, levitin said. in judaism, the torah was set to music as a way to remember it before it was written down. " the structures that respond to music in the brain evolved earlier than the structures that respond to language, " levitin said. levitin points out that many of our ancestors, before there was writing, used music to help them remember things, such as how to prepare foods or the way to get to a water source. these procedural tasks would have been easier to remember as songs. today, we still use songs to teach children things in school, like the 50 states. what about remembering how to play music? when you sit down at the piano and learn how to play a song, your brain has to execute what ' s known as a " motor - action plan. " it means that a sequence of events must unfold in a particular order, your fingers must hit a precise pattern of notes in order. and you rehearse those motor movements over and over, strengthening the neural circuits the more you practice. but musicians who memorize how to play music often find they can ' t just begin a remembered piece at any point in the song. the brain has a certain number of entry nodes in the motor - action plan, so you can only access the information from particular points in the song. " even though it feels like it ' s in your fingers,


at any point in the song. the brain has a certain number of entry nodes in the motor - action plan, so you can only access the information from particular points in the song. " even though it feels like it ' s in your fingers, it ' s not, " levitin said. " it ' s in the finger representation in your head. " music and pleasure music is strongly associated with the brain ' s reward system. it ' s the part of the brain that tells us if things are valuable, or important or relevant to survival, said robert zatorre, professor of neurology and neurosurgery at montreal neurological institute. one brain structure in particular, called the striatum, releases a chemical called dopamine in response to pleasure - related stimuli. imaging of the brain can reveal this process is similar to what happens in your brain in response to food or sex. but unlike those activities, music doesn ' t have a direct biological survival value. " it ' s not obvious that it should engage that same system, " zatorre said. musicians can ' t see inside their own brains, but they ' re aware of moments of tension and release in pieces, and that ' s what arrangers of music do. zatorre and colleagues did an experiment where they used whatever music participants said gave them pleasure to examine this dopamine release. they excluded music with words in order to focus on the music itself rather than lyrics - - the melodic structure, for example. at the point in a piece of music when people experience peak pleasure, part of the brain called the ventral striatum releases dopamine. but here ' s something even more interesting : dopamine is released from a different brain area ( the dorsal striatum ) about 10 to 15 seconds before the moment of peak pleasure. why would we have this reaction before the most pleasurable part of the piece of music? the brain likes to investigate its environment and figure out what ' s coming next, zatorre explains. " as you ' re anticipating a moment of pleasure, you ' re making predictions about what you ' re hearing and what you ' re about to hear, " he said. " part of the pleasure we derive from it is being able to make predictions. " so if you ' re getting such a strong dopamine rush from music - - it could even be comparable to methamphetamines, zatorre said - - why not make drug addicts listen to music? it ' s


" so if you ' re getting such a strong dopamine rush from music - - it could even be comparable to methamphetamines, zatorre said - - why not make drug addicts listen to music? it ' s not quite that simple. neuroscientists believe there ' s basically one pleasure mechanism, and music is one route into it. drugs are another. but different stimuli have different properties. and it ' s no easier to tell someone to replace drugs with music than to suggest eating instead of having sex - - these are all pleasurable activities with important differences. rocking to the beat did you know that monkeys can ' t tap their feet to songs, or recognize beats? it appears that humans are the only primates who move to the beat of music. aniruddh patel at the neurosciences institute in san diego, california, speculates that this is because our brains are organized in a different way than our close species relatives. grooving to a beat may be related to the fact that no other primates can mimic complex sounds. curiously, some birds can mimic what they hear and move to beats. patel ' s research with a cockatoo suggests the beat responses may have originated as a byproduct of vocal mimicry, but also play a role in social bonding, patel said. armies train by marching to a beat, for instance. group dancing is a social activity. there also are studies showing that when people move together to a beat, they ' re more likely to cooperate with each other in nonmusical tasks than if they ' re not in synch. " some people have theorized that that was the original function of this behavior in evolution : it was a way of bonding people emotionally together in groups, through shared movement and shared experience, " patel said. another exciting arena of research : music with a beat seems to help people with motor disorders such as parkinson ' s disease walk better than in the absence of music - - patients actually synchronize their movements to a beat, patel said. " that ' s a very powerful circuit in the brain, " he said. " it can actually help people that have these serious neurological diseases. " there ' s also some evidence to suggest that music can help alzheimer ' s patients remember things better, and that learning new skills such as musical instruments might even stave off dementia. there still needs to be more research in these areas to confirm, but limb is hopeful about the prospect of musical engagement as a way to prevent


s patients remember things better, and that learning new skills such as musical instruments might even stave off dementia. there still needs to be more research in these areas to confirm, but limb is hopeful about the prospect of musical engagement as a way to prevent, or at least delay, dementia. " that ' s a pretty amazing thing that, from sound, you can stimulate the entire brain, " limb said. " if you think about dementia as the opposite trend, of the brain atrophying, i think there ' s a lot of basis to it. " music and emotions you may associate particular songs with events in your life - - green day ' s " good riddance ( time of your life ) " might remind you of your graduation day, if you had a graduation in the 1990s or 2000s, for example. despite variation in any given person ' s life experience, studies have shown that music listeners largely agree with one another when it comes to the emotions presented in a song. this may be independent of lyrics ; musical sounds themselves may carry emotional meaning, writes cornell university psychologist carol krumhansl in current directions in psychological science. educational shows such as " sesame street " have been tapping into the power of music to help youngsters remember things for decades. even babies have been shown to be sensitive to beats and can recognize a piece of music that they ' ve already heard. advertisers exploit music in many commercials to make you excited about products. as a result, you may associate songs with particular cars, for instance. here ' s one way you might not already be using music : making a deliberate effort to use music to alter mood. listen to something that makes you energetic at the beginning of the day, and listen to a soothing song after an argument, levitin says. music as a language victor wooten of bela fleck and the flecktones isn ' t a scientist, but he has thought a lot about the process of learning to play music. for him, introducing a child to music shouldn ' t be different from the way a child begins speaking. " i just approach music as a language, because it is, " wooten said. " it serves the same purpose. it ' s a form of expression. a way for me to express myself, convey feelings, and sometimes it actually works better than a written or verbal language. " traditionally, a child learns to play music by being taught how an instrument works, and learning to play easy pieces that they practice over and over. they might also play music


feelings, and sometimes it actually works better than a written or verbal language. " traditionally, a child learns to play music by being taught how an instrument works, and learning to play easy pieces that they practice over and over. they might also play music with other beginners. all the rules come first - - notes, chords, notation - - before they play. but with language, young children never know that they ' re beginners, wooten said. no one makes them feel bad when they say a word incorrectly, and they ' re not told to practice that word dozens of times. why should it be different with music? " if you think about trying to teach a toddler how to read, and the alphabet, and all that stuff, before they can speak, we ' d realize how silly that really is, " wooten said. " kids most of the time quit, because they didn ' t come there to learn that. they came to learn to play. " he remembers learning to play music in an immersive way, rather than in a formulaic sequence of lessons. when he was born, his four older brothers were already playing music and knew they needed a bass player to complete the band. " my brothers never said, ' this is what you ' re going to do, ' " he said. wooten took this philosophy and created summer camps to get kids excited about music in a more natural way. " it ' s rare that i ever meet a musician who doesn ' t agree that music is a language. but it ' s very rare to meet a musician that really treats it like one. " there you have it : music that gets stuck in your head can be annoying, but it also serves a multitude of other purposes that benefit you. if you treat it like a language, as wooten suggests, you might learn new skills and reap some of the brain health benefits that neurologists are exploring. it ' s more complicated than " a, b, c, " but that ' s how amazing the mind can be.


ece497 project ideas we have both mini projects and projects in ece497. mini projects involved finding something interested in the beagle world and installing it to your beagle and demoing it to the class. you would also create a wiki page documenting what you did to get it installed. often you may find multiple efforts do to something, for example there are a few efforts to port android on the beagle. your task is to figure out which one should be used. generally mini projects won ' t require you to write new code ; however they are the background work that may lead to a full project. you should do a couple mini projects for the class. generally they are done alone, but working in pairs is ok. these will be about 1 / 3 of your grade and should be done in the first 5 weeks or so. only one full project is done for the class and it ' s done with a team of 3 or 4. these projects can take a mini project ( or a whole new idea ) and add to it. the goal is to have your work contribute to the open source world. any code is generated will be kept on github and a bitbake receipt will be created to automatically download and create the object files. what follows are - places to look for project ideas - feel free to add your own suggestions. - mini project ideas - add your own suggestions, and do some of them. mark the ones you ' ve done. - full project ideas sources for project ideas here are some links where you ' ll find ideas for your project. - etechdays community lightning talks, this is a one - day web - based conference where many project ideas are presented. one of our 2009 - 2010 senior design projects was found here. - official list of beagle projects, there are many beagle specific projects listed here. many are inactive. list your project here once it running. - augmented reality project, here ' s an idea that i think we can do on the beagle. rather than using augmented reality glasses, i ' d suggest we use a ti dlp pico projector. here ' s ar running on the beagle. - android, this is one of a couple of efforts to port google ' s android os to the beagle. - beagleboard / ideas - 2009 google summer code ideas 2009. mini project ideas | mark a. yoder | | jack ma | | work up an example of controlling the pwm registers from the shell. | |


the beagle. - beagleboard / ideas - 2009 google summer code ideas 2009. mini project ideas | mark a. yoder | | jack ma | | work up an example of controlling the pwm registers from the shell. | | pwm via the shell | | mark a. yoder | | weather station | | ultrasonic weather | | mark a. yoder | | mike yuhas | | interface the beagleboard with an srf08 ultrasonic ranger over i2c | | ultrasonic ranger | | mark a. yoder | | compile the powervr examples | | powervr insider sdk downloads | | mark a. yoder | | work up some gstreamer ps eye demos | | gstreamer ps eye demos and ridgerun | | mark a. yoder | | douglas selby | | get ti ' embedded speech recognizer installed and demo the examples. | | ti embedded speech recognizer | | mark a. yoder | | david zitnik | | demo last year ' s ti speech project. i have a microphone amplifier and mike you can use. | | ece597 project pywikireader | | mark a. yoder | | stephen mayhew | | find who is doing what with kinect on the beagle and install and run it. | | google - beagleboard kinect | | mark a. yoder | | greg harrison | | i have several sony playstation eye web cams and i have examples of how to pull video from them via v4l2 ( ece497 davinci workshop labs ). the eye also has a 4 microphone array. i don ' t know how to get audio from it. figure out how. this may expand to a full project if there is no solution out there. | | google - beagleboard playstation eye microphone array | | mark a. yoder | | find some examples of how to use cmem. cmem is an api and library for managing one or more blocks of physically contiguous memory. it also provides address translation services ( e. g. virtual to physical translation ) and user - mode cache management apis. it ' s used for managing the shared memory between the arm and the dsp on the processor. i ' ve been unable to find examples of how to use it. | | cmem overview | | mike lester | | connect to your beagleboard using ethernet over usb. this allows your beagleboard to share


dsp on the processor. i ' ve been unable to find examples of how to use it. | | cmem overview | | mike lester | | connect to your beagleboard using ethernet over usb. this allows your beagleboard to share the host computer ' s internet connection and allow you to connect via vnc / ssh without the need for an external router / switch. this should make development much easier. | | vnc | | brian hulette | | experiment with audio synthesis and / or sampling / processing. you could either synthesize and play a few tones to generate a song, or have the beagle sample an audio signal then process and output it to create a sort of effects pedal. | | david mcginnis | | david mcginnis | | look into connecting the beagleboard to a phone or headphones using bluetooth. this could involve either outputting audio and taking in audio from a bluetooth headset, allowing you to have audio i / o with the beagleboard, or could involve connecting with phones automatically as they come into range of the beagleboard, allowing for an automatic attendence registration system, among other things. | | david bliss | | david bliss | | get a video stream from a ps eye, and identify the relevant device files. | | playstation _ eye # cite _ note - linux _ support - 32 | | william gerth | | william gerth | | explore the possibility of implementing openaos on the beagle, to make a portable media player and etc. | | http : / / www. openaos. org / | | joel carlson | | lacking a serial port and don ' t have a usb - serial converter? why not find a way to make the beagleboard boot over a usb console connection? | | beagleboard xm u - boot without serial | | joel carlson | | joel carlson | | depending on what one is working on, it might be useful to mount the beagleboard root filesystem over nfs. the link to the right does that using a usb - ethernet connection, but one that just runs over an ethernet cable would be nice. | | mount beagleboard root filesystem over nfs via usb here ' s an example of mounting dfs / afs on the beagle | lei liu | | lei liu | | build communication with fpga via usb port. | | aaron bamberger | | aaron bamberger | | play around with the beagle


an example of mounting dfs / afs on the beagle | lei liu | | lei liu | | build communication with fpga via usb port. | | aaron bamberger | | aaron bamberger | | play around with the beagleboard ' s various spi and i2c ports, and get it to talk to some simple spi and i2c peripherals, such as a 7 - segment display driver or small lcd panel | | jay dial | | jay dial | | look into the parallel computing possibilities of the beagleboard. see how difficult it would be to get two beagleboards to communicate properly for parallel computing. | | how to make a beagleboard elastic r beowulf cluster | | randy billingsley | | randy billingsley | | configure wlan on the beagle board using a wireless usb adapter | | mike fuson | | mike fuson | | get xbmc working on the beagle. | | xbmc wiki page | | sam allen | | port android to beagle | | it ' s done. check out this. | | mark a. yoder | | yifei li | | change the splash screen to a rose logo when the beagle starts up | | how to change angstrom boot logo in beagleboard | | mark a. yoder | | ziyi zhang | | do remote debugging with eclipse. my page needs updating. | | ece497 installing the eclipse ide | | mark a. yoder | | investigate eigen. eigen is a c + + template library for linear algebra : matrices, vectors, numerical solvers, and related algorithms. explicit vectorization is performed for sse 2 / 3 / 4, arm neon, and altivec instruction sets, with graceful fallback to non - vectorized code. this means it should run fast on the beagle. how fast does it run? has anyone used it on the beagle? | | eigen. tuxfamily. org | | mark a. yoder | | find what libraries are available for the dsp side of the dm 3730 and write some examples that use them. | | c64x + dsp library ( dsplib ) | | mark a. yoder | | convert the oss labs to use the new alsa drivers | | alsa tutorials | | mark a. yoder | | dig into the dss drivers. the


library ( dsplib ) | | mark a. yoder | | convert the oss labs to use the new alsa drivers | | alsa tutorials | | mark a. yoder | | dig into the dss drivers. the omap display subsystem supports rotation and mirroring, but the mirror and rotate files in / sys / devices / platform / omapdss / display x don ' t work. find the code that implements them see if you can figure out what ' s wrong. | | dss2 | | jack ma | | install an rt kernel on beagleboard. if successful, this could turn into a full project for exploring rt system and application. | | jack ma | | interface beagleboard with a gps device to read location information. if successful, see if it ' s possible build a ( small ) app that downloads appropriate map from google map and shows the beagleboard ' s location. | | jack ma | | install a vpn server on beagleboard. | | guanqun wang | | run beagle board with a small lcd display | | yifei li | | demo a beaglelight program that could synchronize leds with music. | | http : / / processors. wiki. ti. com / index. php / beaglelight | | mona yan | | mona yan | | display beagleboard orientation by using accelerometer and opengl. | | team members | | project title | | description | | mark a. yoder | | 3d structured light using dlp® technology | | create 3d maps using a dlp pico and the beagle. | | mark a. yoder | | beagle midi | | make the beagle synthesize midi files. | | mark a. yoder | | beagle power management | | work up some power management demos. | edit this page to add projects you would like to do. if you aren ' t in the class, add ideas you would like to see done by class members. | team members | | project title | | description | | mark a. yoder | | ti embedded speech recognizer | | port ti ' s fixed - point speech recognizer to the dsp. it currently runs on the arm. | | mark a. yoder | | kinect | | here and here are some interesting things people are doing with kinects. maybe we could port it to the beagle. |


the dsp. it currently runs on the arm. | | mark a. yoder | | kinect | | here and here are some interesting things people are doing with kinects. maybe we could port it to the beagle. | | mike lester | | accelerometer - based auto - leveled projection | | several projects have been started to add accelerometer support to the beagleboard. this project would involve getting an accelerometer installed and working, perhaps using a trainer board, as well the ti pico projector. the orientation data from the accelerometer would be used to rotate, skew, keystone the projected image in order to keep it level and normalized. | | aaron bamberger | | kinect based 3d scanner | | build some sort of motorized gantry that allows the kinect to be rotated around ( and possibly from top to bottom ) of an arbitrary object. the motors would be controlled using the beagleboard ' s i2c or spi interfaces. use libfreenect to capture depth information from every side of the object as the kinect rotates around the object. use this data and opengl to build a 3d model of the scanned object | | mark a. yoder | | port windsk6 to the beagle | | windsk6 is a windows program that talks to a ti ' c6711 dsk and performs many interesting audio effects. this project would implement the code running on the windows side on the arm. the arm could capture a frame of audio and send it to the dsp for processing. the arm could then send the processed audio to the speakers. c6run would be used to interact with the dsp. | | david bliss | | automated die tester | | make a device that can roll a die, and keep statistics on how random the die is. the build can either be very complex, or very simple, depending on how you define " rolling a die ". the software doesn ' t necessarily have to know what the numbers mean, it just has to be able to uniquely identify the sides. | | stephen mayhew | | set - playing system | | set is a relatively simple card game that lends itself nicely to image recognition and computer play. the layout is not very structured, and the game play is pretty simple. this project would incorporate image recognition, projection of possible moves ( using the pico projector ), and maybe even speech synthesis, and recognition. for example,


computer play. the layout is not very structured, and the game play is pretty simple. this project would incorporate image recognition, projection of possible moves ( using the pico projector ), and maybe even speech synthesis, and recognition. for example, if someone didn ' t know how to play set, then the board could take them through a tutorial, asking questions of the user as it went along ( " if i have these 2 cards, what 3rd card would make a set? " ). this would make for an interesting demo at conferences. | | michael fuson | spectrum analyzer | | create a real - time audio spectrum analyzer on the beagleboard. project page | | team members | | project title | | description | | yannick polius | | pywikireader | | this project is mostly software, with the hardware element being the use of the dsp. the idea is to tie together three technologies : speech recognition, speech synthesis, and internet access in order to create an interface capable of orating information to the user based on a vocal command. the implementation i have in mind is to use the pocket sphinx speech recognition engine to first understand what the user wants through speech, such as " rose - hulman ". once the speech is translated, the software can execute a wikipedia search to pull said item ' s page. most of the important info is contained within the introductory paragraph, so the software will take only that chunk and feed it into the flite speech synthesis engine. the end result is a simple machine with " mother box " like usability, that is, no interaction besides what is natural to the user ( speaking ) should be necessary to retrieve the information. | | paul morrison | 3d chess with networking | | this project would simulate a hand - held chess game, and the game would allow two player games using two beagleboards over a network connection. the graphics would use the beagle ' s powervr sgx for hardware accelerated graphics by using opengl. in addition to 3d graphics and networking, a third portion of the project would be to optimize the boot time because a chess computer should start up quickly. | | tom most | sumo robot | | the goal of this project is to create a robot capable of competing in the 3. 0 kg weight class of a sumo competition ( an example ). this would have minor hardware and electronics elements, but would focus on communication with sensors using the beagleboard and the linux kernel. at minimum, this involves sensors


competing in the 3. 0 kg weight class of a sumo competition ( an example ). this would have minor hardware and electronics elements, but would focus on communication with sensors using the beagleboard and the linux kernel. at minimum, this involves sensors to detect the edge of the ring and the opposing robot. this would likely be implemented using sharp ir rangefinders, a ultrasonic rangefinders, and ideally a camera. sumo rules. | | ece597 network based mp3 player | | network based mp3 player. the beagle will be programmed using a custom, protocol for transferring files from a network based server ( x86 pc ) to a beagle. speakers will be attached to the beagle, where the file will be played back. possible extensions are a lcd for displaying id3 tag information, and buttons for user interaction ( next track, previous track, etc. ) on the gpio interface. | | chris routh j. cody collins greg jackson keqiong xin | ece597 : auto hud | | use the beagle board to run image recognition on a camera feed located inside a car, and then signaling to the driver via a pico projector various objects of interest. | | adam jesionowski | adding sense to beagle ( see beagleboard / gsoc / ideas ) | | sensory aware applications are becoming more mainstream with the release of the apple iphone. this project would combine both hw and sw to add sensory awareness to beagle. first, additional modules such as gps, 3 - axis accelerometers, gyroscopes, temperature sensors, humidity sensors, pressure sensors, etc, would be added to beagle to compliment the microphone input in order to allow sensing of the real world environment. then sw apis would need to be layered on top to allow easy access to the sensory data for use by applications. | | mitch garvin | interactive pong | | run classic pong, projecting the screen and using a camera to track user ' s hands for input. |


before her enlistment as an ss auxiliary, she worked at an office in berlin. on january 31, 1941, margot dreschel arrived at ravensbruck concentration camp to receive guard training. at first she was an aufseherin, a lower - ranking female guard at ravensbruck camp in charge of interned women. she trained under oberaufseherin ( senior overseer ) johanna langefeld in 1941, and quickly became an ss - rapportfuhrerin ( report overseer ), a higher - ranked guard. on april 27, 1942, dreschel was selected for transfer to the newly opened auschwitz ii – birkenau concentration camp in occupied poland. dreschel began her duties at birkenau in august 1942 as soon as the women ' s camp was established there, with women transferred from auschwitz to birkenau during expansion. she served under maria mandel and worked as an associate of dr mengele. dreschel was also head of all camp offices in auschwitz. dreschel ' s appearance was reportedly repellent, as one female auschwitz prisoner recounted : " camp leader dreschel was there, her buck teeth sticking out, even when her mouth is closed. " inmates described her as vulgar, thin and ugly. after the war, many survivors testified of her notoriously brutal beatings. she carried out indoor selections wearing a white coat and white gloves, disguised as a doctor. once mrs drechaler [ dreschler ] came, with her huge bloodhound, undressed everybody, took away even our shoes, and we had to stand for hours completely naked, none of us were thinking of life any more, the gas chamber seemed unavoidable. — war crimes trials. protocol 3309, ss female overseers in auschwitz she regularly moved between the auschwitz i camp and birkenau, and involved herself in selections of women and children to be sent to the gas chambers. on november 1, 1944, she went to flossenburg concentration camp as an oberaufseherin - and as trainer of enlisted overseers. in january 1945, she was moved back to the ravensbruck subcamp at neustadt - glewe, and fled from there in april 1945 as nazi germany surrendered. in may 1945, several former auschwitz prisoners recognized her on a road from pirna to bautzen in the russian zone, and took her to the russian military police. the soviets condemned her to death and executed her in may or june 1945 by hanging


novgorod first chronicle | | this article relies largely or entirely upon a single source. ( september 2011 ) | the novgorod first chronicle ( russian : новгородская первая летопись ) or the chronicle of novgorod, 1016 - 1471 is the most ancient extant chronicle of the novgorod republic. it reflects a tradition different from the kievan primary chronicle. as was first demonstrated by aleksey shakhmatov, the later editions of the chronicle reflect the lost primary kievan code ( начальныи киевскии свод ) of the late 11th century, which contained much valuable data suppressed in the later primary chronicle. the earliest extant copy of the chronicle is the so - called synod scroll, dated to the second half of the 13th century, first printed in 1841 and currently preserved in the state historical museum. it is the earliest known manuscript of a major east slavic chronicle, predating the laurentian codex of the primary chronicle by almost a century. in the 14th century, the synod scroll was continued by the monks of the yuriev monastery in novgorod. other important copies of the novgorod first chronicle include the academic scroll ( 241 lists, 1444 ), commission scroll ( 320 lists, mid - 15th century ), trinity scroll ( 1563 ), and tolstoy scroll ( 208 lists, 1720s ).


| | this article needs additional citations for verification. ( march 2011 ) | nuclear meltdown is an informal term for a severe nuclear reactor accident that results in core damage from overheating. the term is not officially defined by the international atomic energy agency or by the u. s. nuclear regulatory commission. however, it has been defined to mean the accidental melting of the core of a nuclear reactor, and is in common usage a reference to the core ' s either complete or partial collapse. " core melt accident " and " partial core melt " are the analogous technical terms for a meltdown. a core melt accident occurs when the heat generated by a nuclear reactor exceeds the heat removed by the cooling systems to the point where at least one nuclear fuel element exceeds its melting point. this differs from a fuel element failure, which is not caused by high temperatures. a meltdown may be caused by a loss of coolant, loss of coolant pressure, or low coolant flow rate or be the result of a criticality excursion in which the reactor is operated at a power level that exceeds its design limits. alternately, in a reactor plant such as the rbmk - 1000, an external fire may endanger the core, leading to a meltdown. once the fuel elements of a reactor begin to melt, the fuel cladding has been breached, and the nuclear fuel ( such as uranium, plutonium, or thorium ) and fission products ( such as cesium - 137, krypton - 88, or iodine - 131 ) within the fuel elements can leach out into the coolant. subsequent failures can permit these radioisotopes to breach further layers of containment. superheated steam and hot metal inside the core can lead to fuel - coolant interactions, hydrogen explosions, or water hammer, any of which could destroy parts of the containment. a meltdown is considered very serious because of the potential, however remote, that radioactive materials could breach all containment and escape ( or be released ) into the environment, resulting in radioactive contamination and fallout, and potentially leading to radiation poisoning of people and animals nearby. nuclear power plants generate electricity by heating fluid via a nuclear reaction to run a generator. if the heat from that reaction is not removed adequately, the fuel assemblies in a reactor core can melt. a core damage incident can occur even after a reactor is shut down because the fuel continues to produce decay heat. a core damage accident is caused by the loss of sufficient cooling for the nuclear fuel within the reactor core. the reason may be one


melt. a core damage incident can occur even after a reactor is shut down because the fuel continues to produce decay heat. a core damage accident is caused by the loss of sufficient cooling for the nuclear fuel within the reactor core. the reason may be one of several factors, including a loss - of - pressure - control accident, a loss - of - coolant accident ( loca ), an uncontrolled power excursion or, in reactors without a pressure vessel, a fire within the reactor core. failures in control systems may cause a series of events resulting in loss of cooling. contemporary safety principles of defense in depth ensure that multiple layers of safety systems are always present to make such accidents unlikely. the containment building is the last of several safeguards that prevent the release of radioactivity to the environment. many commercial reactors are contained within a 1. 2 - to - 2. 4 - metre ( 3. 9 to 7. 9 ft ) thick pre - stressed, steel - reinforced, air - tight concrete structure that can withstand hurricane - force winds and severe earthquakes. - in a loss - of - coolant accident, either the physical loss of coolant ( which is typically deionized water, an inert gas, nak, or liquid sodium ) or the loss of a method to ensure a sufficient flow rate of the coolant occurs. a loss - of - coolant accident and a loss - of - pressure - control accident are closely related in some reactors. in a pressurized water reactor, a loca can also cause a " steam bubble " to form in the core due to excessive heating of stalled coolant or by the subsequent loss - of - pressure - control accident caused by a rapid loss of coolant. in a loss - of - forced - circulation accident, a gas cooled reactor ' s circulators ( generally motor or steam driven turbines ) fail to circulate the gas coolant within the core, and heat transfer is impeded by this loss of forced circulation, though natural circulation through convection will keep the fuel cool as long as the reactor is not depressurized. - in a loss - of - pressure - control accident, the pressure of the confined coolant falls below specification without the means to restore it. in some cases this may reduce the heat transfer efficiency ( when using an inert gas as a coolant ) and in others may form an insulating " bubble " of steam surrounding the fuel assemblies ( for pressurized water reactors ). in the latter case, due to localized heating of the "


efficiency ( when using an inert gas as a coolant ) and in others may form an insulating " bubble " of steam surrounding the fuel assemblies ( for pressurized water reactors ). in the latter case, due to localized heating of the " steam bubble " due to decay heat, the pressure required to collapse the " steam bubble " may exceed reactor design specifications until the reactor has had time to cool down. ( this event is less likely to occur in boiling water reactors, where the core may be deliberately depressurized so that the emergency core cooling system may be turned on ). in a depressurization fault, a gas - cooled reactor loses gas pressure within the core, reducing heat transfer efficiency and posing a challenge to the cooling of fuel ; however, as long as at least one gas circulator is available, the fuel will be kept cool. - in an uncontrolled power excursion accident, a sudden power spike in the reactor exceeds reactor design specifications due to a sudden increase in reactor reactivity. an uncontrolled power excursion occurs due to significantly altering a parameter that affects the neutron multiplication rate of a chain reaction ( examples include ejecting a control rod or significantly altering the nuclear characteristics of the moderator, such as by rapid cooling ). in extreme cases the reactor may proceed to a condition known as prompt critical. this is especially a problem in reactors that have a positive void coefficient of reactivity, a positive temperature coefficient, are overmoderated, or can trap excess quantities of deleterious fission products within their fuel or moderators. many of these characteristics are present in the rbmk design, and the chernobyl disaster was caused by such deficiencies as well as by severe operator negligence. western light water reactors are not subject to very large uncontrolled power excursions because loss of coolant decreases, rather than increases, core reactivity ( a negative void coefficient of reactivity ) ; " transients, " as the minor power fluctuations within western light water reactors are called, are limited to momentary increases in reactivity that will rapidly decrease with time ( approximately 200 % - 250 % of maximum neutronic power for a few seconds in the event of a complete rapid shutdown failure combined with a transient ). - core - based fires endanger the core and can cause the fuel assemblies to melt. a fire may be caused by air entering a graphite moderated reactor, or a liquid - sodium cooled reactor. graphite is also subject to accumulation of wigner energy, which can overhea


the core and can cause the fuel assemblies to melt. a fire may be caused by air entering a graphite moderated reactor, or a liquid - sodium cooled reactor. graphite is also subject to accumulation of wigner energy, which can overheat the graphite ( as happened at the windscale fire ). light water reactors do not have flammable cores or moderators and are not subject to core fires. gas - cooled civilian reactors, such as the magnox, ungg, and agcr type reactors, keep their cores blanketed with non reactive carbon dioxide gas, which cannot support a fire. modern gas - cooled civilian reactors use helium, which cannot burn, and have fuel that can withstand high temperatures without melting ( such as the high temperature gas cooled reactor and the pebble bed modular reactor ). - byzantine faults and cascading failures within instrumentation and control systems may cause severe problems in reactor operation, potentially leading to core damage if not mitigated. for example, the browns ferry fire damaged control cables and required the plant operators to manually activate cooling systems. the three mile island accident was caused by a stuck - open pilot - operated pressure relief valve combined with a deceptive water level gauge that misled reactor operators, which resulted in core damage. light water reactors ( lwrs ) before the core of a light water nuclear reactor can be damaged, two precursor events must have already occurred : - a limiting fault ( or a set of compounded emergency conditions ) that leads to the failure of heat removal within the core ( the loss of cooling ). low water level uncovers the core, allowing it to heat up. - failure of the emergency core cooling system ( eccs ). the eccs is designed to rapidly cool the core and make it safe in the event of the maximum fault ( the design basis accident ) that nuclear regulators and plant engineers could imagine. there are at least two copies of the eccs built for every reactor. each division ( copy ) of the eccs is capable, by itself, of responding to the design basis accident. the latest reactors have as many as four divisions of the eccs. this is the principle of redundancy, or duplication. as long as at least one eccs division functions, no core damage can occur. each of the several divisions of the eccs has several internal " trains " of components. thus the eccs divisions themselves have internal redundancy – and can withstand failures of components within them. the three mile island accident was a compounded


occur. each of the several divisions of the eccs has several internal " trains " of components. thus the eccs divisions themselves have internal redundancy – and can withstand failures of components within them. the three mile island accident was a compounded group of emergencies that led to core damage. what led to this was an erroneous decision by operators to shut down the eccs during an emergency condition due to gauge readings that were either incorrect or misinterpreted ; this caused another emergency condition that, several hours after the fact, led to core exposure and a core damage incident. if the eccs had been allowed to function, it would have prevented both exposure and core damage. during the fukushima incident the emergency cooling system had also been manually shut down several minutes after it started. if such a limiting fault were to occur, and a complete failure of all eccs divisions were to occur, both kuan, et al and haskin, et al describe six stages between the start of the limiting fault ( the loss of cooling ) and the potential escape of molten corium into the containment ( a so - called " full meltdown " ) : - uncovering of the core – in the event of a transient, upset, emergency, or limiting fault, lwrs are designed to automatically scram ( a scram being the immediate and full insertion of all control rods ) and spin up the eccs. this greatly reduces reactor thermal power ( but does not remove it completely ) ; this delays core becoming uncovered, which is defined as the point when the fuel rods are no longer covered by coolant and can begin to heat up. as kuan states : " in a small - break loca with no emergency core coolant injection, core uncovery [ sic ] generally begins approximately an hour after the initiation of the break. if the reactor coolant pumps are not running, the upper part of the core will be exposed to a steam environment and heatup of the core will begin. however, if the coolant pumps are running, the core will be cooled by a two - phase mixture of steam and water, and heatup of the fuel rods will be delayed until almost all of the water in the two - phase mixture is vaporized. the tmi - 2 accident showed that operation of reactor coolant pumps may be sustained for up to approximately two hours to deliver a two phase mixture that can prevent core heatup. " - pre - damage heat up – " in the absence of a two - phase mixture going through the core


operation of reactor coolant pumps may be sustained for up to approximately two hours to deliver a two phase mixture that can prevent core heatup. " - pre - damage heat up – " in the absence of a two - phase mixture going through the core or of water addition to the core to compensate water boiloff, the fuel rods in a steam environment will heat up at a rate between 0. 3 °c / s ( 0. 5 °f / s ) and 1 °c / s ( 1. 8 °f / s ) ( 3 ). " - fuel ballooning and bursting – " in less than half an hour, the peak core temperature would reach 1, 100 k ( 1, 520 °f ). at this temperature the zircaloy cladding of the fuel rods may balloon and burst. this is the first stage of core damage. cladding ballooning may block a substantial portion of the flow area of the core and restrict the flow of coolant. however complete blockage of the core is unlikely because not all fuel rods balloon at the same axial location. in this case, sufficient water addition can cool the core and stop core damage progression. " - rapid oxidation – " the next stage of core damage, beginning at approximately 1, 500 k ( 2, 240 °f ), is the rapid oxidation of the zircaloy by steam. in the oxidation process, hydrogen is produced and a large amount of heat is released. above 1, 500 k ( 2, 240 °f ), the power from oxidation exceeds that from decay heat ( 4, 5 ) unless the oxidation rate is limited by the supply of either zircaloy or steam. " - debris bed formation – " when the temperature in the core reaches about 1, 700 k ( 2, 600 °f ), molten control materials [ 1, 6 ] will flow to and solidify in the space between the lower parts of the fuel rods where the temperature is comparatively low. above 1, 700 k ( 2, 600 °f ), the core temperature may escalate in a few minutes to the melting point of zircaloy [ 2, 150 k ( 3, 410 °f ) ] due to increased oxidation rate. when the oxidized cladding breaks, the molten zircaloy, along with dissolved uo2 [ 1, 7 ] would flow downward and freeze in the cooler, lower region of the core. together with solidified control materials from earlier down - flows, the relocated zircaloy and uo2 would form the lower crust of a developing


[ 1, 7 ] would flow downward and freeze in the cooler, lower region of the core. together with solidified control materials from earlier down - flows, the relocated zircaloy and uo2 would form the lower crust of a developing cohesive debris bed. " - ( corium ) relocation to the lower plenum – " in scenarios of small - break locas, there is generally a pool of water in the lower plenum of the vessel at the time of core relocation. release of molten core materials into water always generates large amounts of steam. if the molten stream of core materials breaks up rapidly in water, there is also a possibility of a steam explosion. during relocation, any unoxidized zirconium in the molten material may also be oxidized by steam, and in the process hydrogen is produced. recriticality also may be a concern if the control materials are left behind in the core and the relocated material breaks up in unborated water in the lower plenum. " at the point at which the corium relocates to the lower plenum, haskin, et al relate that the possibility exists for an incident called a fuel - coolant interaction ( fci ) to substantially stress or breach the primary pressure boundary when the corium relocates to the lower plenum of the reactor pressure vessel ( " rpv " ). this is because the lower plenum of the rpv may have a substantial quantity of water - the reactor coolant - in it, and, assuming the primary system has not been depressurized, the water will likely be in the liquid phase, and consequently dense, and at a vastly lower temperature than the corium. since corium is a liquid metal - ceramic eutectic at temperatures of 2, 200 to 3, 200 k ( 3, 500 to 5, 300 °f ), its fall into liquid water at 550 to 600 k ( 530 to 620 °f ) may cause an extremely rapid evolution of steam that could cause a sudden extreme overpressure and consequent gross structural failure of the primary system or rpv. though most modern studies hold that it is physically infeasible, or at least extraordinarily unlikely, haskin, et al state that that there exists a remote possibility of an extremely violent fci leading to something referred to as an alpha - mode failure, or the gross failure of the rpv itself, and subsequent ejection of the upper plenum of


al state that that there exists a remote possibility of an extremely violent fci leading to something referred to as an alpha - mode failure, or the gross failure of the rpv itself, and subsequent ejection of the upper plenum of the rpv as a missile against the inside of the containment, which would likely lead to the failure of the containment and release of the fission products of the core to the outside environment without any substantial decay having taken place. breach of the primary pressure boundary there are several possibilities as to how the primary pressure boundary could be breached by corium. - steam explosion as previously described, fci could lead to an overpressure event leading to rpv fail, and thus, primary pressure boundary fail. haskin, et al. report that in the event of a steam explosion, failure of the lower plenum is far more likely than ejection of the upper plenum in the alpha - mode. in the even of lower plenum failure, debris at varied temperatures can be expected to be projected into the cavity below the core. the containment may be subject to overpressure, though this is not likely to fail the containment. the alpha - mode failure will lead to the consequences previously discussed. - pressurized melt ejection ( pme ) it is quite possible, especially in pressurized water reactors, that the primary loop will remain pressurized following corium relocation to the lower plenum. as such, pressure stresses on the rpv will be present in addition to the weight stress that the molten corium places on the lower plenum of the rpv ; when the metal of the rpv weakens sufficiently due to the heat of the molten corium, it is likely that the liquid corium will be discharged under pressure out of the bottom of the rpv in a pressurized stream, together with entrained gases. this mode of corium ejection may lead to direct containment heating ( dch ). severe accident ex - vessel interactions and challenges to containment haskin, et al identify six modes by which the containment could be credibly challenged ; some of these modes are not applicable to core melt accidents. - dynamic pressure ( shockwaves ) - internal missiles - external missiles ( not applicable to core melt accidents ) standard failure modes if the melted core penetrates the pressure vessel, there are theories and speculations as to what may then occur. in modern russian plants, there is a " core catching device " in the


missiles ( not applicable to core melt accidents ) standard failure modes if the melted core penetrates the pressure vessel, there are theories and speculations as to what may then occur. in modern russian plants, there is a " core catching device " in the bottom of the containment building, the melted core is supposed to hit a thick layer of a " sacrificial metal " which would melt, dilute the core and increase the heat conductivity, and finally the diluted core can be cooled down by water circulating in the floor. however there has never been any full - scale testing of this device. in western plants there is an airtight containment building. though radiation would be at a high level within the containment, doses outside of it would be lower. containment buildings are designed for the orderly release of pressure without releasing radionuclides, through a pressure release valve and filters. hydrogen / oxygen recombiners also are installed within the containment to prevent gas explosions. in a melting event, one spot or area on the rpv will become hotter than other areas, and will eventually melt. when it melts, corium will pour into the cavity under the reactor. though the cavity is designed to remain dry, several nureg - class documents advise operators to flood the cavity in the event of a fuel melt incident. this water will become steam and pressurize the containment. automatic water sprays will pump large quantities of water into the steamy environment to keep the pressure down. catalytic recombiners will rapidly convert the hydrogen and oxygen back into water. one positive effect of the corium falling into water is that it is cooled and returns to a solid state. extensive water spray systems within the containment along with the eccs, when it is reactivated, will allow operators to spray water within the containment to cool the core on the floor and reduce it to a low temperature. these procedures are intended to prevent release of radiation. in the three mile island event in 1979, a theoretical person standing at the plant property line during the entire event would have received a dose of approximately 2 millisieverts ( 200 millirem ), between a chest x - ray ' s and a ct scan ' s worth of radiation. this was due to outgassing by an uncontrolled system that, today, would have been backfitted with activated carbon and hepa filters to prevent radionuclide release. however in case of fukushima incident this design also at least partially failed : large amounts of highly radioactive water were produced and


system that, today, would have been backfitted with activated carbon and hepa filters to prevent radionuclide release. however in case of fukushima incident this design also at least partially failed : large amounts of highly radioactive water were produced and nuclear fuel has possibly melted through the base of the pressure vessels. cooling will take quite a while, until the natural decay heat of the corium reduces to the point where natural convection and conduction of heat to the containment walls and re - radiation of heat from the containment allows for water spray systems to be shut down and the reactor put into safe storage. the containment can be sealed with release of extremely limited offsite radioactivity and release of pressure within the containment. after a number of years for fission products to decay - probably around a decade - the containment can be reopened for decontamination and demolition. unexpected failure modes another scenario sees a buildup of hydrogen, which may lead to a detonation event, as happened for three reactors during fukushima incident. catalytic hydrogen recombiners located within containment are designed to prevent this from occurring ; however, prior to the installation of these recombiners in the 1980s, the three mile island containment ( in 1979 ) suffered a massive hydrogen explosion event in the accident there. the containment withstood the pressure and no radioactivity was released. however, in fukushima recombiners did not work due the absence of power and hydrogen detonation breached the containment. speculative failure modes one scenario consists of the reactor pressure vessel failing all at once, with the entire mass of corium dropping into a pool of water ( for example, coolant or moderator ) and causing extremely rapid generation of steam. the pressure rise within the containment could threaten integrity if rupture disks could not relieve the stress. exposed flammable substances could burn, but there are few, if any, flammable substances within the containment. another theory called an ' alpha mode ' failure by the 1975 rasmussen ( wash - 1400 ) study asserted steam could produce enough pressure to blow the head off the reactor pressure vessel ( rpv ). the containment could be threatened if the rpv head collided with it. ( the wash - 1400 report was replaced by better - based [ original research? ] newer studies, and now the nuclear regulatory commission has disavowed them all and is preparing the overarching state - of - the - art reactor consequence analyses [ soarca ] study - see the disclaimer in nureg - 115


newer studies, and now the nuclear regulatory commission has disavowed them all and is preparing the overarching state - of - the - art reactor consequence analyses [ soarca ] study - see the disclaimer in nureg - 1150. ) it has not been determined to what extent a molten mass can melt through a structure ( although that was tested in the loss - of - fluid - test reactor described in test area north ' s fact sheet ). the three mile island accident provided some real - life experience, with an actual molten core within an actual structure ; the molten corium failed to melt through the reactor pressure vessel after over six hours of exposure, due to dilution of the melt by the control rods and other reactor internals, validating the emphasis on defense in depth against core damage incidents. some believe a molten reactor core could actually penetrate the reactor pressure vessel and containment structure and burn downwards into the earth beneath, to the level of the groundwater. by 1970, there were doubts about the ability of the emergency cooling systems of a nuclear reactor to prevent a loss of coolant accident and the consequent meltdown of the fuel core ; the subject proved popular in the technical and the popular presses. in 1971, in the article thoughts on nuclear plumbing, former manhattan project ( 1942 – 1946 ) nuclear physicist ralph lapp used the term " china syndrome " to describe a possible burn - through, after a loss of coolant accident, of the nuclear fuel rods and core components melting the containment structures, and the subsequent escape of radioactive material ( s ) into the atmosphere and environment ; the hypothesis derived from a 1967 report by a group of nuclear physicists, headed by w. k. ergen. the geographic, planet - piercing concept of the china syndrome derives from the misperception that china is the antipode of the united states ; to many americans, it is the “ the other side of the world ”. moreover, the hypothetical transit of a meltdown product to the other side of the earth ( i. e. china ) ignores the fact that the earth ' s gravity tends to pull all masses towards its center. assuming a meltdown product could persist in a mobile molten form for long enough to reach the center of the earth ; gravity would prevent it continuing to the other side. other reactor types other types of reactors have different capabilities and safety profiles than the lwr does. advanced varieties of several of these reactors have the potential to be inherently safe. candu reactors candu reactors, canadian - invented de


to the other side. other reactor types other types of reactors have different capabilities and safety profiles than the lwr does. advanced varieties of several of these reactors have the potential to be inherently safe. candu reactors candu reactors, canadian - invented deuterium - uranium design, are designed with at least one, and generally two, large low - temperature and low - pressure water reservoirs around their fuel / coolant channels. the first is the bulk heavy - water moderator ( a separate system from the coolant ), and the second is the light - water - filled shield tank. these backup heat sinks are sufficient to prevent either the fuel meltdown in the first place ( using the moderator heat sink ), or the breaching of the core vessel should the moderator eventually boil off ( using the shield tank heat sink ). other failure modes aside from fuel melt will probably occur in a candu rather than a meltdown, such as deformation of the calandria into a non - critical configuration. all candu reactors are located within standard western containments as well. gas - cooled reactors one type of western reactor, known as the advanced gas - cooled reactor ( or agcr ), built by the united kingdom, is not very vulnerable to loss - of - cooling accidents or to core damage except in the most extreme of circumstances. by virtue of the relatively inert coolant ( carbon dioxide ), the large volume and high pressure of the coolant, and the relatively high heat transfer efficiency of the reactor, the time frame for core damage in the event of a limiting fault is measured in days. restoration of some means of coolant flow will prevent core damage from occurring. other types of highly advanced gas cooled reactors, generally known as high - temperature gas - cooled reactors ( htgrs ) such as the japanese high temperature test reactor and the united states ' very high temperature reactor, are inherently safe, meaning that meltdown or other forms of core damage are physically impossible, due to the structure of the core, which consists of hexagonal prismatic blocks of silicon carbide reinforced graphite infused with triso or quadriso pellets of uranium, thorium, or mixed oxide buried underground in a helium - filled steel pressure vessel within a concrete containment. though this type of reactor is not susceptible to meltdown, additional capabilities of heat removal are provided by using regular atmospheric airflow as a means of backup heat removal, by having it pass through a heat exchanger and rising into the atmosphere due to convection, achieving full residual heat


is not susceptible to meltdown, additional capabilities of heat removal are provided by using regular atmospheric airflow as a means of backup heat removal, by having it pass through a heat exchanger and rising into the atmosphere due to convection, achieving full residual heat removal. the vhtr is scheduled to be prototyped and tested at idaho national laboratory within the next decade ( as of 2009 ) as the design selected for the next generation nuclear plant by the us department of energy. this reactor will use a gas as a coolant, which can then be used for process heat ( such as in hydrogen production ) or for the driving of gas turbines and the generation of electricity. a similar highly advanced gas cooled reactor originally designed by west germany ( the avr reactor ) and now developed by south africa is known as the pebble bed modular reactor. it is an inherently safe design, meaning that core damage is physically impossible, due to the design of the fuel ( spherical graphite " pebbles " arranged in a bed within a metal rpv and filled with triso ( or quadriso ) pellets of uranium, thorium, or mixed oxide within ). a prototype of a very similar type of reactor has been built by the chinese, htr - 10, and has worked beyond researchers ' expectations, leading the chinese to announce plans to build a pair of follow - on, full - scale 250 mwe, inherently safe, power production reactors based on the same concept. ( see nuclear power in the people ' s republic of china for more information. ) experimental or conceptual designs some design concepts for nuclear reactors emphasize resistance to meltdown and operating safety. the pius ( process inherent ultimate safety ) designs, originally engineered by the swedes in the late 1970s and early 1980s, are lwrs that by virtue of their design are resistant to core damage. no units have ever been built. power reactors, including the deployable electrical energy reactor, a larger - scale mobile version of the triga for power generation in disaster areas and on military missions, and the triga power system, a small power plant and heat source for small and remote community use, have been put forward by interested engineers, and share the safety characteristics of the triga due to the uranium zirconium hydride fuel used. the hydrogen moderated self - regulating nuclear power module, a reactor that uses uranium hydride as a moderator and fuel, similar in chemistry and safety to the triga, also possesses these extreme safety and stability characteristics, and has attracted a good deal