file compression is to perform some algorithm on the file that reduces it in size but the reverse of the algorithm will return it to its original form. in data files, the compression and decompression must be lossless which means that the data must be returned to its exact form. there are various methods to do this : some hardware implementations and some software. the most popular ones that are implemented in hardware usually use a limpel - ziv algorithm to look for repeating sequences over a set span of data ( the run ) and replace that with special identifying information. compression does save space but may take extra time ( latency ). video and music data are typically already compressed. the compression rates are usually very high because of the data and the fact that a lossy compression algorithm is used. it can be lossy ( meaning that all bits may not be decompressed exactly ) because it won ' t be noticeable with video or music. zip files are the result of software compression. another compression round on already compressed data will probably not yield any substantial gain. evaluator group, inc. editor ' s note : do you agree with this expert ' s response? if you have more to share, post it in our storage networking forum at http : / / searchstorage. discussions. techtarget. com / webx? 50 @ @. ee83ce4 or e - mail us directly at firstname. lastname @ example. org. this was first published in december 2001


may 20, 2009 the cook islands are closely associated to new zealand. air new zealand is the only air carrier that flies directly from the u. s. to the cook islands. as you will see below, the cook islands use the nzd as their currency. despite some 90, 000 visitors a year to the capital island, rarotonga, the cook islands are largely unspoiled by tourism. there are no high - rise hotels, only four beach buggies and very little hype. the cook islands offer a rare opportunity for an authentic island holiday. there are a total of 15 islands in the heart of the south pacific spread over 850, 000 square miles with a population of approximately 15, 000. the islands most visited are rarotonga and aitutaki which are only 140 miles apart. cook island history ru, from tupua ’ i in french polynesia, is believed to have landed on aitutaki, and tangiia, also from french polynesia, is believed to have arrived on rarotonga around 800 ad. similarly, the northern islands were probably settled by expeditions from samoa and tonga. cook island climate cooled by the gentle breezes of the pacific, the climate of these islands is sunny and pleasant. roughly speaking, there are two seasons : from november through may the climate is hot and humid, and from june through october the climate is warm and dry. most of the rain falls during the hot season, but there are also many lovely sunny days during these months, with refreshing trade - winds. cook island geography the cook islands consists of two main groups, one in the north and one in the south. the southern group is nine “ high ” islands mainly of volcanic origin although some are virtually atolls. the majority of the population lives in the southern group. the northern group comprises six true atolls. cook island southern group aitutaki, atiu, mangaia, manuae, mauke, mitiaro, palmerston, rarotonga ( the capital island ), takutea. cook island northern group manihiki, nassau, tongareva ( penrhyn ) also known as mangarongaro, pukapuka, rakahanga, suwarrow cook island time zones rarotonga and aitutaki are in the same time zone. cook island currency new zealand dollar. cook island language english and cook island maori. call the “ island travel gal ” at 800 644 - 6659 or email email @ example. com to secure


classroom activities for teaching sedimentary geologythis collection of teaching materials allows for the sharing of ideas and activities within the community of geoscience teachers. do you have a favorite teaching activity you ' d like to share? please help us expand this collection by contributing your own teaching materials. subject : sedimentary geology results 1 - 4 of 4 matches chemical and physical weathering field and lab experiment : development and testing of hypotheses part of activities lisa greer, washington and lee university this exercise combines an integrated field and laboratory experiment with a significant scientific writing assignment to address chemical and physical weathering processes via hypothesis development, experimental... demystifying the equations of sedimentary geology part of activities larry lemke, wayne state university this activity includes three strategies to help students develop a deeper comfort level and stronger intuitive sense for understanding mathematical expressions commonly encountered in sedimentary geology. each can... digital sandstone tutorial part of activities kitty milliken, university of texas at austin, the the tutorial petrographic image atlas is designed to give students more exposure to petrographic features than they can get during organized laboratory periods. red rock and concretion models from earth to mars : teaching diagenesis part of activities margie chan, university of utah this activity teaches students concepts of terrestrial diagenesis ( cementation, fluid flow, porosity and permeability, concretions ) and encourages them to apply those concepts to new or unknown settings, including...


- exam wrappers. as david thompson describes the process, " exam wrappers required students to reflect on their performance before and after seeing their graded tests. " the first four questions, completed just prior to receiving their graded test, asked students to report the time they spent preparing for the test, their methods of preparation, and their predicted test grade. after reviewing their graded test, students completed the final three reflection questions, including a categorization of test mistakes and a list of changes to implement in preparation for the next test. thompson then collected and made copies of the wrappers returned them to the students several days later, reminding them to consider what they planned to do differently or the same in preparation for the upcoming test. thompson reports that each reflection exercise required only 8 - 10 minutes of class time. clara hardy and others also describes uses exam wrappers. - reading reflections. as karl wirth writes, reading reflections, effectively outlined by david bressoud ( 2008 ), are designed to address some of the challenges students face with college - level reading assignments. students submit online reading reflections ( e. g., using moodle or blackboard ) after completing each reading assignment and before coming to class. in each reflection, students summarize the important concepts of the reading and describe what was interesting, surprising, or confusing to them. the reading reflections not only encourage students to read regularly before class, but they also promote content mastery and foster student development of monitoring, self - evaluation, and reflection skills. for the instructor, reading reflections facilitate " just - in - time " teaching and provide invaluable insights into student thinking and learning. according to wirth, expert readers are skilled at using a wide range of strategies during all phases of reading ( e. g., setting goals for learning, monitoring comprehension during reading, checking comprehension, and self - reflection ), but most college instruction simply assumes the mastery of such metacognitive skills. - knowledge surveys. many members of the group were influenced by karl wirth ' s work on " knowledge surveys " as a central strategy for helping students think about their thinking. knowledge surveys involve simple self - reports from students about their knowledge of course concepts and content. in knowledge surveys, students are presented with different facets of course content and are asked to indicate whether they know the answer, know some of the answer, or don ' t know the answer. faculty can use these reports to gauge how confident students feel in their understanding of course material at the beginning or end of a course, before


asked to indicate whether they know the answer, know some of the answer, or don ' t know the answer. faculty can use these reports to gauge how confident students feel in their understanding of course material at the beginning or end of a course, before exams or papers, or even as graduating seniors or alumni. kristin bonnie ' s report relates how her students completed a short knowledge survey ( 6 - 12 questions ) online ( via google forms ) on the material covered in class that week. rather than providing the answer to each question, students indicated their confidence in their ability to answer the question correctly ( i know ; i think i know ; i don ' t know ). students received a small amount of credit for completing the knowledge survey. she used the information to review material that students seemed to struggle with. in addition, a subset of these questions appeared on their exam – the knowledge survey therefore served as a review sheet. wirth notes that the surveys need not take much class time and can be administered via paper or the web. the surveys can be significant for clarifying course objectives, structure, and design. for students, knowledge surveys achieve several purposes : they help make clear course objectives and expectations, are useful as study guides, can serve as a formative assessment tool, and, perhaps most critically, aid in their development of self - assessment and metacognitive skills. for instructors, the surveys help them assess learning gains, instructional practices, and course design.


free the cans! working together to reduce waste in a blog about how people share, it ’ s worth the occasional reference to the bizarre ways that people don ’ t share. is it safe to say we live in a society that places great value on independence, private property, personal space, and privacy? even sometimes extreme value? is that why people at an 8 - unit apartment building in oakland, ca have separate caged stalls for eight separate trash cans? i know it ’ s not nice to stare, but i walked by these incarcerated cans and could not help myself. i returned with my camera, so that i could share my question with the world : why can ’ t people share trash cans or a single dumpster? or, at the very least, why can ’ t the cans share driveway space? the zero waste movement has come to the bay area and it calls for a new use for these eight cages. here are my suggestions : - turn two of those cages into compost bins. fill one with grass, leaves, and vegetable scraps, let it decompose for six months, then start filling the second bin in the meantime. - put in a green can, which is what oakland uses to collect milk cartons, pizza boxes, yard trimmings, and all food to send it to the municipal composting facility. if your city doesn ’ t do this yet, tell them it ’ s a great idea and they could be as cool and cutting edge as oakland. - put in one or two recycling cans for glass, plastic, cardboard, paper, aluminum, etc. - put out a free stuff box for unwanted clothing and household items. the neighbors could sort through it each week, and later put it out on the curb for passers - by to explore. take what ’ s left to goodwill or a comparable donation spot. - put in a few small bins for various items that can be recycled, such asbatteries and electronics, which can then be taken to an electronics recycling center every month or two. styrofoam can be brought to a local packaging store or ceramics business that accepts used packaging material. or, if you accumulate a bunch of plastic bags, take them to a store or to some other place that accepts used ones. - put in one trash can. by the time you compost, recycle, re - use, redistribute, and take a few other measures to reduce your waste, you ’ ll have almost no trash each week.


excerpts for thames : the biography the river as fact it has a length of 215 miles, and is navigable for 191 miles. it is the longest river in england but not in britain, where the severn is longer by approximately 5 miles. nevertheless it must be the shortest river in the world to acquire such a famous history. the amazon and the mississippi cover almost 4, 000 miles, and the yangtze almost 3, 500 miles ; but none of them has arrested the attention of the world in the manner of the thames. it runs along the borders of nine english counties, thus reaffirming its identity as a boundary and as a defence. it divides wiltshire from gloucestershire, and oxfordshire from berkshire ; as it pursues its way it divides surrey from middlesex ( or greater london as it is inelegantly known ) and kent from essex. it is also a border of buckinghamshire. it guarded these once tribal lands in the distant past, and will preserve them into the imaginable future. there are 134 bridges along the length of the thames, and forty - four locks above teddington. there are approximately twenty major tributaries still flowing into the main river, while others such as the fleet have now disappeared under the ground. its " basin, " the area from which it derives its water from rain and other natural forces, covers an area of some 5, 264 square miles. and then there are the springs, many of them in the woods or close to the streams beside the thames. there is one in the wood below sinodun hills in oxfordshire, for example, which has been described as an " everlasting spring " always fresh and always renewed. the average flow of the river at teddington, chosen because it marks the place where the tidal and non - tidal waters touch, has been calculated at 1, 145 millions of gallons ( 5, 205 millions of litres ) each day or approximately 2, 000 cubic feet ( 56. 6 cubic metres ) per second. the current moves at a velocity between 1u2 and 23u4 miles per hour. the main thrust of the river flow is known to hydrologists as the " thalweg " ; it does not move in a straight and forward line but, mingling with the inner flow and the variegated flow of the surface and bottom waters, takes the form of a spiral or helix. more than 95 per cent of the river ' s energy is lost in turbulence and friction. the direction of the flow of the thames is therefore quixotic. it might be assumed that it


bottom waters, takes the form of a spiral or helix. more than 95 per cent of the river ' s energy is lost in turbulence and friction. the direction of the flow of the thames is therefore quixotic. it might be assumed that it would move eastwards, but it defies any simple prediction. it flows north - west above henley and at teddington, west above abingdon, south from cookham and north above marlow and kingston. this has to do with the variegated curves of the river. it does not meander like the euphrates, where according to herodotus the voyager came upon the same village three times on three separate days, but it is circuitous. it specialises in loops. it will take the riparian traveller two or three times as long to cover the same distance as a companion on the high road. so the thames teaches you to take time, and to view the world from a different vantage. the average " fall " or decline of the river from its beginning to its end is approximately 17 to 21 inches ( 432 to 533 mm ) per mile. it follows gravity, and seeks out perpetually the simplest way to the sea. it falls some 600 feet ( 183 m ) from source to sea, with a relatively precipitous decline of 300 feet ( 91. 5 m ) in the first 9 miles ; it falls 100 ( 30. 4 m ) more in the next 11 miles, with a lower average for the rest of its course. yet averages may not be so important. they mask the changeability and idiosyncrasy of the thames. the mean width of the river is given as 1, 000 feet ( 305 m ), and a mean depth of 30 feet ( 9 m ) ; but the width varies from 1 or 2 feet ( 0. 3 to 0. 6 m ) at trewsbury to 51u2 miles at the nore. the tide, in the words of tennyson, is that which " moving seems asleep, too full for sound and foam. " on its flood inward it can promise benefit or danger ; on its ebb seaward it suggests separation or adventure. it is one general movement but it comprises a thousand different streams and eddies ; there are opposing streams, and high water is not necessarily the same thing as high tide. the water will sometimes begin to fall before the tide is over. the average speed of the tide lies between 1 and 3 knots ( 1. 15 and 3. 45 miles


opposing streams, and high water is not necessarily the same thing as high tide. the water will sometimes begin to fall before the tide is over. the average speed of the tide lies between 1 and 3 knots ( 1. 15 and 3. 45 miles per hour ), but at times of very high flow it can reach 7 knots ( 8 miles per hour ). at london bridge the flood tide runs for almost six hours, while the ebb tide endures for six hours and thirty minutes. the tides are much higher now than at other times in the history of the thames. there can now be a difference of some 24 feet ( 7. 3 m ) between high and low tides, although the average rise in the area of london bridge is between 15 and 22 feet ( 4. 5 and 6. 7 m ). in the period of the roman occupation, it was a little over 3 feet ( 0. 9 m ). the high tide, in other words, has risen greatly over a period of two thousand years. the reason is simple. the south - east of england is sinking slowly into the water at the rate of approximately 12 inches ( 305 mm ) per century. in 4000 bc the land beside the thames was 46 feet ( 14 m ) higher than it is now, and in 3000 bc it was some 31 feet ( 9. 4 m ) higher. when this is combined with the water issuing from the dissolution of the polar ice - caps, the tides moving up the lower reaches of the thames are increasing at a rate of 2 feet ( 0. 6 m ) per century. that is why the recently erected thames barrier will not provide protection enough, and another barrier is being proposed. the tide of course changes in relation to the alignment of earth, moon and sun. every two weeks the high " spring " tides reach their maximum two days after a full moon, while the low " neap " tides occur at the time of the half - moon. the highest tides occur at the times of equinox ; this is the period of maximum danger for those who live and work by the river. the spring tides of late autumn and early spring are also hazardous. it is no wonder that the earliest people by the thames venerated and propitiated the river. the general riverscape of the thames is varied without being in any sense spectacular, the paraphernalia of life ancient and modern clustering around its banks. it is in large part now a domesticated river, having been tamed and controlled by many generations. it


of the thames is varied without being in any sense spectacular, the paraphernalia of life ancient and modern clustering around its banks. it is in large part now a domesticated river, having been tamed and controlled by many generations. it is in that sense a piece of artifice, with some of its landscape deliberately planned to blend with the course of the water. it would be possible to write the history of the thames as a history of a work of art. it is a work still in slow progress. the thames has taken the same course for ten thousand years, after it had been nudged southward by the glaciation of the last ice age. the british and roman earthworks by the sinodun hills still border the river, as they did two thousand years before. given the destructive power of the moving waters, this is a remarkable fact. its level has varied over the millennia - - there is a sudden and unexpected rise at the time of the anglo - saxon settlement, for example - - and the discovery of submerged forests testifies to incidents of overwhelming flood. its appearance has of course also altered, having only recently taken the form of a relatively deep and narrow channel, but its persistence and identity through time are an aspect of its power. yet of course every stretch has its own character and atmosphere, and every zone has its own history. out of oppositions comes energy, out of contrasts beauty. there is the overwhelming difference of water within it, varying from the pure freshwater of the source through the brackish zone of estuarial water to the salty water in proximity to the sea. given the eddies of the current, in fact, there is rather more salt by the essex shore than by the kentish shore. there are manifest differences between the riverine landscapes of lechlade and of battersea, of henley and of gravesend ; the upriver calm is in marked contrast to the turbulence of the long stretches known as river of london and then london river. after new bridge the river becomes wider and deeper, in anticipation of its change. the rural landscape itself changes from flat to wooded in rapid succession, and there is a great alteration in the nature of the river from the cultivated fields of dorchester to the thick woods of cliveden. from godstow the river becomes a place of recreation, breezy and jaunty with the skiffs and the punts, the sports in port meadow and the picnic parties on the banks by binsey. but then by some change of light it becomes dark green, surrounded


becomes a place of recreation, breezy and jaunty with the skiffs and the punts, the sports in port meadow and the picnic parties on the banks by binsey. but then by some change of light it becomes dark green, surrounded by vegetation like a jungle river ; and then the traveller begins to see the dwellings of oxford, and the river changes again. oxford is a pivotal point. from there you can look upward and consider the quiet source ; or you can look downstream and contemplate the coming immensity of london. in the reaches before lechlade the water makes its way through isolated pastures ; at wapping and rotherhithe the dwellings seem to drop into it, as if overwhelmed by numbers. the elements of rusticity and urbanity are nourished equally by the thames. that is why parts of the river induce calm and forgetfulness, and others provoke anxiety and despair. it is the river of dreams, but it is also the river of suicide. it has been called liquid history because within itself it dissolves and carries all epochs and generations. they ebb and flow like water. the river as metaphor the river runs through the language, and we speak of its influence in every conceivable context. it is employed to characterise life and death, time and destiny ; it is used as a metaphor for continuity and dissolution, for intimacy and transitoriness, for art and history, for poetry itself. in the principles of psychology ( 1890 ) william james first coined the phrase " stream of consciousness " in which " every definite image of the mind is steeped... in the free water that flows around it. " thus " it flows " like the river itself. yet the river is also a token of the unconscious, with its suggestion of depth and invisible life. the river is a symbol of eternity, in its unending cycle of movement and change. it is one of the few such symbols that can readily be understood, or appreciated, and in the continuing stream the mind or soul can begin to contemplate its own possible immortality. in the poetry of john denham ' s " cooper ' s hill " ( 1642 ), the thames is a metaphor for human life. how slight its beginning, how confident its continuing course, how ineluctable its destination within the great ocean : hasting to pay his tribute to the sea, like mortal life to meet eternity. the poetry of the thames has always emphasised its affiliations with human purpose and with human realities


course, how ineluctable its destination within the great ocean : hasting to pay his tribute to the sea, like mortal life to meet eternity. the poetry of the thames has always emphasised its affiliations with human purpose and with human realities. so the personality of the river changes in the course of its journey from the purity of its origins to the broad reaches of the commercial world. the river in its infancy is undefiled, innocent and clear. by the time it is closely pent in by the city, it has become dank and foul, defiled by greed and speculation. in this regress it is the paradigm of human life and of human history. yet the river has one great advantage over its metaphoric companions. it returns to its source, and its corruption can be reversed. that is why baptism was once instinctively associated with the river. the thames has been an emblem of redemption and of renewal, of the hope of escaping from time itself. when wordsworth observed the river at low tide, with the vista of the " mighty heart " of london " lying still, " he used the imagery of human circulation. it is the image of the river as blood, pulsing through the veins and arteries of its terrain, without which the life of london would seize up. sir walter raleigh, contemplating the thames from the walk by his cell in the tower, remarked that the " blood which disperseth itself by the branches or veins through all the body, may be resembled to these waters which are carried by brooks and rivers overall the earth. " he wrote his history of the world ( 1610 ) from his prison cell, and was deeply imbued with the current of the thames as a model of human destiny. it has been used as the symbol for the unfolding of events in time, and carries the burden of past events upon its back. for raleigh the freight of time grew ever more complex and wearisome as it proceeded from its source ; human life had become darker and deeper, less pure and more susceptible to the tides of affairs. there was one difference raleigh noticed in his history, when he declared that " for this tide of man ' s life, after it once turneth and declineth, ever runneth with a perpetual ebb and falling stream, but never floweth again. " the thames has also been understood as a mirror of morality. the bending rushes and the yielding willows afford lessons in humility and forbearance ; the humble weeds along its banks have been praised for their lowliness


never floweth again. " the thames has also been understood as a mirror of morality. the bending rushes and the yielding willows afford lessons in humility and forbearance ; the humble weeds along its banks have been praised for their lowliness and absence of ostentation. and who has ventured upon the river without learning the value of patience, of endurance, and of vigilance? john denham makes the thames the subject of native discourse in a further sense : though deep, yet clear ; though gentle, yet not dull ; strong without rage ; without o ' erflowing, full. this suggests that the river represents an english measure, an aesthetic harmony to be sought or wished for, but in the same breath denham seems to be adverting to some emblem of englishness itself. the thames is a metaphor for the country through which it runs. it is modest and moderate, calm and resourceful ; it is powerful without being fierce. it is not flamboyantly impressive. it is large without being too vast. it eschews extremes. it weaves its own course without artificial diversions or interventions. it is useful for all manner of purposes. it is a practical river. when robert menzies, an erstwhile australian prime minister, was taken to runnymede he was moved to comment upon the " secret springs " of the " slow english character. " this identification of the land with the people, the characteristics of the earth and water with the temperament of their inhabitants, remains a poignant one. there is an inward and intimate association between the river and those who live beside it, even if that association cannot readily be understood. from the hardcover edition.


teach your child the importance of good sportsmanship. not too long ago, my 10 - year - old daughter ' s indoor soccer team finished their game and lined up to do the traditional end - of - game walk with the other team. if your own child has ever played in a team sport, you likely have seen this walk a hundred times before. win or lose, each member of the team is expected to essentially tell the other players they did well and good game. this is a classic way to end a game on a positive note and to exhibit good sportsmanship, win or lose. the opposing team in this case, however, had a unique way of showing their good sportsmanship. they all licked their hands before holding them out for our own girls to " low - five " as they walked down the line. our girls saw this, and they refused to touch the other girls ' slimy, slobbery, germ - ridden hands. you may be wondering if our girls ' team beat this other team. the truth is that they beat the other team pretty harshly, but there is no score that would justify the level of poor sportsmanship that the other team exhibited. as a parent, i can only hope the parents or coach on the other team reprimanded their girls for this unsportsmanlike behavior. this is not the kind of behavior any parent would be proud to see in their own child. however, this is just one of many ways unsportsmanlike behavior is exhibited. from tears on the field to pushing, shoving, " trash talking " and more, there are many different behaviors that are associated with poor sportsmanship. the fact is that good sportsmanship is a quality that can play a role in your child ' s ability to react to other situations throughout life. competition may occur on the field, but it also plays a part in the college admission process, a run for a place on the school board, the job application process and so much more. teaching your child how to be a good sport now can help him or her to handle wins and losses throughout life with grace. so how can you help your child build a healthy " win - or - lose " attitude? a positive parental role model no parent takes pride in seeing other players, either from their child ' s own team or on the opposing team, be better than their own child. parents simply want their child to be the best. however, somewhere between the desire to see your kid to aim for the stars and the truth of reality is the


child ' s own team or on the opposing team, be better than their own child. parents simply want their child to be the best. however, somewhere between the desire to see your kid to aim for the stars and the truth of reality is the fact that there always will be someone or some team that is better. as a parent, you can talk negatively about these better players or better teams, or you can talk positively about them. you can use these interactions with better competition to point out areas where your own child can improve and to teach your child to respect those with skills and talents that are worthy of respect. this is a great opportunity to teach your child to turn lemons into lemonade. you win some, you lose some very few children really are the best at what they do. there is always someone who either is better now or who is working hard to be better in the near future. a team that was on top this season may not be the top team the next season. while you want your child to work hard and strive to win, it is unrealistic to expect a child or his or her team to win all of the time. children will inevitably be disappointed after a loss. this is understandable and justified, especially if he or she has been working hard and did his or her personal best. as a parent, your response to a loss is every bit as important as your response to a win. the fact is that an entire team can play their best, and they may simply be out - matched. teaching kids that losses do happen, even when they try their hardest, can help them to cope with their defeat. show them that you are proud of their performance and effort at each game rather than letting the tally mark under the " w " column dictate this. a lesson learned the fact is that a child or a team simply will not improve very quickly when they are blowing out the competition on a regular basis. to be the best, you have to play the best. you have to be challenged by the best, and sometimes this means a loss will occur. within each game, whether a win or loss, lies an opportunity for growth, development and improvement. after each game, regardless of the outcome, talk to your child about what he or she did well and what he or she thinks could have been done better. rather than tell your child what you think, ask your child his or her personal opinion on the matter and what the coach said. then, remind your child that these are areas that he


groundhogs, as a species, have a large range in size. there are the medium - sized rodents i grew up with, averaging around 4 kg, and groundhogs — like a certain phil — that are probably more like 14 kg. this is the likely source of my earlier confusion, as that ' s a huge discrepancy in size. evidently, it ' s all in the diet, much like humans. where i grew up, in rural northern minnesota, we called the groundhog a woodchuck ; i thought that the groundhog was some fat cat, east coast, liberal rodent. as it would turn out, they are actually one in the same creature — marmota monax, a member of the squirrel family. woodchucks spend a lot of their time in burrows. it is their safe haven from their many predators, and they are quick to flee to it at the first sign of danger. they will sometimes emit a loud whistle on their way to alert others in the area that something is awry. groundhogs enjoy raiding our gardens and digging up sod, thereby destroying what we ' ve spent countless hours toiling upon. look for groundhog signs. you might not even know there is a groundhog around until your garden has been devoured or your tractor damaged by a collapsed groundhog den. things to look for are large nibble marks on your prized veggies, gnaw marks on the bark of young fruit trees, root vegetables pulled up ( or their tops trimmed off ), groundhog - sized holes ( 25 – 30 cm ) anywhere near your garden, or mounds of dirt near said holes. if you see these signs, take action. don ' t wait or it will be too late! if you know it will be a problem and do nothing, you can ' t blame the animal. set groundhog traps. this technique takes some skill as you need to be able to pick a spot in the path of the animal, camouflage it, and mask your strong human scent. setting a spring trap, whether coil or long - spring, is usually just a matter of compressing the springs and setting a pin that keeps the jaws open into the pan or trigger. make sure your trap is anchored securely with a stake. check your traps often, and dispatch the animal quickly and humanely. shooting them in the head or a hearty whack to the head with club will do the trick. if you can ' t deal with this, you have no business


. check your traps often, and dispatch the animal quickly and humanely. shooting them in the head or a hearty whack to the head with club will do the trick. if you can ' t deal with this, you have no business setting traps. call a professional. guns kill groundhogs. i have never shot a groundhog. i rarely have had problems with them, and they move so damned fast it is difficult to get a shot off. if i had to, i know how i would do it. first, be sure it is legal in your area, and be sure to follow gun safety protocols. after that, it ' s just a matter of learning where your target is going to be comfortable and let their guard down. i would follow their tracks back to their den, find a spot downwind to sit with a clear shooting lane, and make sure nothing you shouldn ' t hit with a bullet is down range. then, i would wait, my sights set on the den, until the groundhog stuck its head up — quick and easy. demolish the groundhog burrows. if you find a couple holes around your yard, they are likely the entrances to an elaborate tunnel maze carved into the earth beneath you. about all you can do, short of digging the whole mess up, is to try and fill it in from the top side. first, fill it with a bunch of rocks and then soil — make sure to really pack it in. this will make it difficult for the groundhog to reclaim its hole without a lot of work. you probably want to do this in tandem with other control methods such as trapping, shooting, or fumigating to prevent the groundhog from just digging a new hole. do some landscaping and build barriers. as with the control of many pests, it is advisable to keep a yard free of brush, undercover, and dead trees. these types of features are attractive to groundhogs as cover, and without it, they are less likely to want to spend time there. if you want to keep a groundhog out of an area, consider a partially buried fence. this will require a lot of work, but it is going to help a lot. make sure it extends up at least a meter, and that it is buried somewhere around 30 cm deep. angle the fencing outward 90 degrees when you bury it, and it will make digging under it a very daunting task for your furry friend. try using fumigants to kill groundhogs.


it is buried somewhere around 30 cm deep. angle the fencing outward 90 degrees when you bury it, and it will make digging under it a very daunting task for your furry friend. try using fumigants to kill groundhogs. what is nice about this product is that you can kill the animal and bury it all in one stroke. the best time to do this is in the spring when the mother will be in the den with her still helpless young. also, the soil will likely be damp, which helps a lot. you should definitely follow the directions on the package, but the way they usually work is that you cover all but one exit, set off the smoke bomb, shove it down the hole, and quickly cover it up. check back in a day or two to see if there is any sign of activity, and if so, do it again or consider a different control method. it is important that you don ' t do this if the hole is next to your house or if there is any risk of a fire. poisons are a last resort. i am not a fan of poisons because it is difficult to target what will eat said poison in the wild. also, you are left with the issue of where the groundhog will die and how bad it will smell if it is somewhere under your house. or, if it is outside somewhere, who will be affected by eating the dead animal? where does it end? if you want to use poison, you ' re on your own. use live traps. this is a good option for those of you not too keen on killing things. try jamming the door open and leaving bait inside for the taking a couple of times so they get used to it. then, set it normally and you ' ve got your groundhog ( or a neighborhood cat ). now what? the relocation is just as important ; you need to choose a place that is far away from other humans and can likely support a groundhog. good luck. predator urine. the idea is simple : form a perimeter around an area you want to protect. if the groundhog doesn ' t recognize the smell as a natural predator, it is probably not going to work too well. look for brands that have wolf and bobcat urine. apply regularly, or as the manufacturer recommends. remember, if it rains, the urine has probably washed away. repellents. another popular method involves pepper - based repellents. these deter groundhogs by tasting horrible and burning their mucous membranes.


in my next few blogs, i will provide an overview of voltage source converter ( vsc ) hvdc technology and its suitability for smart grids operation and control discussed. vsc hvdc is based upon transistor technology and was developed in the 1990 ′ s. the switching element is the insulated gate bipolar thyristor ( igbt ), which can be switched on and off by applying a suitable voltage to the gate ( steering electrode ). because of the more switching operations, and the nature of the semiconductor devices itself, the converter losses are generally higher than those of hvdc classic converters. vsc hvdc is commonly used with underground or submarine cables with a transfer capacity in the range of 10 – 1000 mw, and is suitable to serve as a connection to a wind farm or supply a remote load. vsc hvdc technology has very fast steer and control functionality and is suitable for meshed networks. it is characterised by compactness of the converter stations, due to the reduced need for ac harmonic filters and reactive power compensation. power flow reversal in vsc systems is achieved by reversal of the current, whereas in hvdc classic systems the voltage polarity has to change. an important consequence of this voltage source behavior is the ability to use cheaper and easier to install xlpe cables, instead of the mass - impregnated cables that are needed for hvdc classic. currently, only twelve vsc hvdc projects are in service. a few examples include : estlink, which connects estonia to finland ( 350 mw ), and borwin1, connecting an offshore wind farm to northern germany ( 400 mw ). both are equipped with ±150 kv submarine cables, and the trans bay project in california ( 400 mw ) that consists of 90 km ±200 kv submarine cable. most projects have submarine cable, but some projects include long lengths of underground cable, such as murraylink ( 220 mw, 177 km underground cable ), and nord e. on 1 ( 400 mw, 75km underground cable ). the 500 mw east - west interconnector between ireland and great britain, operating at ±200 kv, is scheduled to go into service in 2012. a 2000 mw 65 km cable interconnector ±320kv as part of the trans european network — between spain and france — is scheduled for commissioning in 2013, and will represent the highest power rating for a vsc hvdc system installed at this time. make sure to check back next


the operations layer defines the operational processes and procedures necessary to deliver information technology ( it ) as a service. this layer leverages it service management concepts that can be found in prevailing best practices such as itil and mof. the main focus of the operations layer is to execute the business requirements defined at the service delivery layer. cloud - like service attributes cannot be achieved through technology alone and require a high level of it service management maturity. change management process is responsible for controlling the life cycle of all changes. the primary objective of change management is to eliminate or at least minimize disruption while desired changes are made to services. change management focuses on understanding and balancing the cost and risk of making the change versus the benefit of the change to either the business or the service. driving predictability and minimizing human involvement are the core principles for achieving a mature service management process and ensuring changes can be made without impacting the perception of continuous availability. standard ( automated ) change non - standard ( mechanized ) change it is important to note that a record of all changes must be maintained, including standard changes that have been automated. the automated process for standard changes should include the creation and population of the change record per standard policy in order to make sure auditability. automating changes also enables other key principles such as : the service asset and configuration management process is responsible for maintaining information on the assets, components, and infrastructure needed to provide a service. critical configuration data for each component, and its relationship to other components, must be accurately captured and maintained. this configuration data should include past and current states and future - state forecasts, and be easily available to those who need it. mature service asset and configuration management processes are necessary for achieving predictability. a virtualized infrastructure adds complexity to the management of configuration items ( cis ) due to the transient nature of the relationship between guests and hosts in the infrastructure. how is the relationship between cis maintained in an environment that is potentially changing very frequently? a service comprises software, platform, and infrastructure layers. each layer provides a level of abstraction that is dependent on the layer beneath it. this abstraction hides the implementation and composition details of the layer. access to the layer is provided through an interface and as long as the fabric is available, the actual physical location of a hosted vm is irrelevant. to provide infrastructure as a service ( iaas ), the configuration and relationship of the components within the fabric must be understood, whereas the details of the configuration within the vms hosted by the fabric are irrelevant. the configuration management system (


is irrelevant. to provide infrastructure as a service ( iaas ), the configuration and relationship of the components within the fabric must be understood, whereas the details of the configuration within the vms hosted by the fabric are irrelevant. the configuration management system ( cms ) will need to be partitioned, at a minimum, into physical and logical ci layers. two configuration management databases ( cmdbs ) might be used ; one to manage the physical cis of the fabric ( facilities, network, storage, hardware, and hypervisor ) and the other to manage the logical cis ( everything else ). the cms can be further partitioned by layer, with separate management of the infrastructure, platform, and software layers. the benefits and trade - offs of each approach are summarized below. cms partitioned by layer cms partitioned into physical and logical table 2 : configuration management system options partitioning logical and physical ci information allows for greater stability within the cms, because cis will need to be changed less frequently. this means less effort will need to be expended to accurately maintain the information. during normal operations, mapping a vm to its physical host is irrelevant. if historical records of a vm ’ s location are needed, ( for example, for auditing or root cause analysis ) they can be traced through change logs. the physical or fabric cmdb will need to include a mapping of fault domains, upgrade domains, and live migration domains. the relationship of these patterns to the infrastructure cis will provide critical information to the fabric management system. the release and deployment management processes are responsible for making sure that approved changes to a service can be built, tested, and deployed to meet specifications with minimal disruption to the service and production environment. where change management is based on the approval mechanism ( determining what will be changed and why ), release and deployment management will determine how those changes will be implemented. the primary focus of release and deployment management is to protect the production environment. the less variation is found in the environment, the greater the level of predictability – and, therefore, the lower the risk of causing harm when new elements are introduced. the concept of homogenization of physical infrastructure is derived from this predictability principle. if the physical infrastructure is completely homogenized, there is much greater predictability in the release and deployment process. while complete homogenization is the ideal, it may not be achievable in the real world. homogenization is a continuum. the closer an environment gets to complete homogeneity,


predictability in the release and deployment process. while complete homogenization is the ideal, it may not be achievable in the real world. homogenization is a continuum. the closer an environment gets to complete homogeneity, the more predictable it becomes and the fewer the risks. full homogeneity means not only that identical hardware models are used, but all hardware configuration is identical as well. when complete hardware homogeneity is not feasible, strive for configuration homogeneity wherever possible. figure 2 : homogenization continuum the scale unit concept drives predictability in capacity planning and agility in the release and deployment of physical infrastructure. the hardware specifications and configurations have been pre - defined and tested, allowing for a more rapid deployment cycle than in a traditional data center. similarly, known quantities of resources are added to the data center when the capacity plan is triggered. however, when the scale unit itself must change ( for example, when a vendor retires a hardware model ), a new risk is introduced to the private cloud. there will likely be a period where both n and n - 1 versions of the scale unit exist in the infrastructure, but steps can be taken to minimize the risk this creates. work with hardware vendors to understand the life cycle of their products and coordinate changes from multiple vendors to minimize iterations of the scale unit change. also, upgrading to the new version of the scale unit should take place one fault domain at a time wherever possible. this will make sure that if an incident occurs with the new version, it can be isolated to a single fault domain. homogenization of the physical infrastructure means consistency and predictability for the vms regardless of which physical host they reside on. this concept can be extended beyond the production environment. the fabric can be partitioned into development, test, and pre - production environments as well. eliminating variability between environments enables developers to more easily optimize applications for a private cloud and gives testers more confidence that the results reflect the realities of production, which in turn should greatly improve testing efficiency. the virtualized infrastructure enables workloads to be transferred more easily between environments. all vms should be built from a common set of component templates housed in a library, which is used across all environments. this shared library includes templates for all components approved for production, such as vm images, the gold os image, server role templates, and platform templates. these component templates are downloaded from the shared library and become the building blocks of the


shared library includes templates for all components approved for production, such as vm images, the gold os image, server role templates, and platform templates. these component templates are downloaded from the shared library and become the building blocks of the development environment. from development, these components are packaged together to create a test candidate package ( in the form of a virtual hard disk ( vhd ) that is uploaded to the library. this test candidate package can then be deployed by booting the vhd in the test environment. when testing is complete, the package can again be uploaded to the library as a release candidate package – for deployment into the pre - production environment, and ultimately into the production environment. since workloads are deployed by booting a vm from a vhd, the release management process occurs very quickly through the transfer of vhd packages to different environments. this also allows for rapid rollback should the deployment fail ; the current release can be deleted and the vm can be booted off the previous vhd. virtualization and the use of standard vm templates allow us to rethink software updates and patch management. as there is minimal variation in the production environment and all services in production are built with a common set of component templates, patches need not be applied in production. instead, they should be applied to the templates in the shared library. any services in production using that template will require a new version release. the release package is then rebuilt, tested, and redeployed, as shown below. figure 3 : the release process this may seem counter - intuitive for a critical patch scenario, such as when an exploitable vulnerability is exposed. but with virtualization technologies and automated test scripts, a new version of a service can be built, tested, and deployed quite rapidly. variation can also be reduced through standardized, automated test scenarios. while not every test scenario can or should be automated, tests that are automated will improve predictability and facilitate more rapid test and deployment timelines. test scenarios that are common for all applications, or the ones that might be shared by certain application patterns, are key candidates for automation. these automated test scripts may be required for all release candidates prior to deployment and would make sure further reduction in variation in the production environment. knowledge management is the process of gathering, analyzing, storing, and sharing knowledge and information within an organization. the goal of knowledge management is to make sure that the right people have access to the information they need to maintain a private cloud. as operational


. knowledge management is the process of gathering, analyzing, storing, and sharing knowledge and information within an organization. the goal of knowledge management is to make sure that the right people have access to the information they need to maintain a private cloud. as operational knowledge expands and matures, the ability to intelligently automate operational tasks improves, providing for an increasingly dynamic environment. an immature approach to knowledge management costs organizations in terms of slower, less - efficient problem solving. every problem or new situation that arises becomes a crisis that must be solved. a few people may have the prior experience to resolve the problem quickly and calmly, but their knowledge is not shared. immature knowledge management creates greater stress for the operations staff and usually results in user dissatisfaction with frequent and lengthy unexpected outages. mature knowledge management processes are necessary for achieving a service provider ’ s approach to delivering infrastructure. past knowledge and experience is documented, communicated, and readily available when needed. operating teams are no longer crisis - driven as service - impacting events grow less frequent and are quickly resolves when they do occur. when designing a private cloud, development of the health model will drive much of the information needed for knowledge management. the health model defines the ideal states for each infrastructure component and the daily, weekly, monthly, and as - needed tasks required to maintain this state. the health model also defines unhealthy states for each infrastructure component and actions to be taken to restore their health. this information will form the foundation of the knowledge management database. aligning the health model with alerts allows these alerts to contain links to the knowledge management database describing the specific steps to be taken in response to the alert. this will help drive predictability as a consistent, proven set of actions will be taken in response to each alert. the final step toward achieving a private cloud is the automation of responses to each alert as defined in the knowledge management database. once these responses are proven successful, they should be automated to the fullest extent possible. it is important to note, though, that automating responses to alerts does not make them invisible and forgotten. even when alerts generate a fully automated response they must be captured in the service management system. if the alert indicates the need for a change, the change record should be logged. similarly, if the alert is in response to an incident, an incident record should be created. these automated workflows must be reviewed regularly by operations staff to make sure the automated action achieves the expected result. finally, as the environment changes over time


, if the alert is in response to an incident, an incident record should be created. these automated workflows must be reviewed regularly by operations staff to make sure the automated action achieves the expected result. finally, as the environment changes over time, or as new knowledge is gained, the knowledge management database must be updated along with the automated workflows that are based on that knowledge. the goal of incident management is to resolve events that are impacting, or threaten to impact, services as quickly as possible with minimal disruption. the goal of problem management is to identify and resolve root causes of incidents that have occurred as well as identify and prevent or minimize the impact of incidents that may occur. pinpointing the root cause of an incident can become more challenging when workloads are abstracted from the infrastructure and their physical location changes frequently. additionally, incident response teams may be unfamiliar with virtualization technologies ( at least initially ) which could also lead to delays in incident resolution. finally, applications may have neither a robust health model nor expose all of the health information required for a proactive response. all of this may lead to an increase in reactive ( user initiated ) incidents which will likely increase the mean - time - to - restore - service ( mtrs ) and customer dissatisfaction. this may seem to go against the resiliency principle, but note that virtualization alone will not achieve the desired resiliency unless accompanied by highly mature it service management ( itsm ) maturity and a robust automated health monitoring system. the drive for resiliency requires a different approach to troubleshooting incidents. extensive troubleshooting of incidents in production negatively impacts resiliency. therefore, if an incident cannot be quickly resolved, the service can be rolled back to the previous version, as described under release and deployment. further troubleshooting can be done in a test environment without impacting the production environment. troubleshooting in the production environment may be limited to moving the service to different hosts ( ruling out infrastructure as the cause ) and rebooting the vms. if these steps do not resolve the issue, the rollback scenario could be initiated. minimizing human involvement in incident management is critical for achieving resiliency. the troubleshooting scenarios described earlier could be automated, which will allow for identification and possible resolution of the root much more quickly than non - automated processes. but automation may mask the root cause of the incident. careful consideration should be given to determining which troubleshooting steps should be automated and which require human analysis. human analysis


identification and possible resolution of the root much more quickly than non - automated processes. but automation may mask the root cause of the incident. careful consideration should be given to determining which troubleshooting steps should be automated and which require human analysis. human analysis of troubleshooting if a compute resource fails, it is no longer necessary to treat the failure as an incident that must be fixed immediately. it may be more efficient and cost effective to treat the failure as part of the decay of the resource pool. rather than treat a failed server as an incident that requires immediate resolution, treat it as a natural candidate for replacement on a regular maintenance schedule, or when the resource pool reaches a certain threshold of decay. each organization must balance cost, efficiency, and risk as it determines an acceptable decay threshold – and choose among these courses of action : the benefits and trade - off of each of the options are listed below : option 4 is the least desirable, as it does not take advantage of the resiliency and cost reduction benefits of a private cloud. a well - planned resource pool and reserve capacity strategy will account for resource decay. option 1 is the most recommended approach. a predictable maintenance schedule allows for better procurement planning and can help avoid conflicts with other maintenance activities, such as software upgrades. again, a well - planned resource pool and reserve capacity strategy will account for resource decay and minimize the risk of exceeding critical thresholds before the scheduled maintenance. option 3 will likely be the only option for self - contained scale unit scenarios, as the container must be replaced as a single scale unit when the decay threshold is reached. the goal of request fulfillment is to manage requests for service from users. users should have a clear understanding of the process they need to initiate to request service and it should have a consistent approach for managing these requests. much like any service provider, it should clearly define the types of requests available to users in the service catalog. the service catalog should include an sla on when the request will be completed, as well as the cost of fulfilling the request, if any. the types of requests available and their associated costs should reflect the actual cost of completing the request and this cost should be easily understood. for example, if a user requests an additional vm, its daily cost should be noted on the request form, which should also be exposed to the organization or person responsible for paying the bill. it is relatively easy to see the need for adding resources, but more difficult to see when a resource is no longer needed. a process for identifying and removing unused v


, which should also be exposed to the organization or person responsible for paying the bill. it is relatively easy to see the need for adding resources, but more difficult to see when a resource is no longer needed. a process for identifying and removing unused vms should be put into place. there are a number of strategies to do this, depending on the needs of a given organization, such as : the benefits and trade - offs of each of these approaches are detailed below : option 4 affords the greatest flexibility, while still working to minimize server sprawl. when a user requests a vm, they have the option of setting an expiration date with no reminder ( for example, if they know they will only be using the workload for one week ). they could set an expiration deadline with a reminder ( for example, a reminder that the vm will expire after 90 days unless they wish to renew ). lastly, the user may request no expiration date if they expect the workload will always be needed. if the last option is chosen, it is likely that underutilized vms will still be monitored and owners notified. finally, self - provisioning should be considered, if appropriate, when evaluating request fulfillment options to drive towards minimal human involvement. self - provisioning allows great agility and user empowerment, but it can also introduce risks depending on the nature of the environment in which these vms are introduced. for an enterprise organization, the risk of bypassing formal build, stabilize, and deploy processes may or may not outweigh the agility benefits gained from the self - provisioning option. without strong governance to make sure each vm has an end - of - life strategy, the fabric may become congested with vm server sprawl. the pros and cons of self - provisioning options are listed in the next diagram : the primary decision point for determining whether to use self - provisioning is the nature of the environment. allowing developers to self - provision into the development environment greatly facilitates agile development, and allows the enterprise to maintain release management controls as these workloads are moved out of development and into test and production environments. a user - led community environment isolated from enterprise mission - critical applications may also be a good candidate for self - provisioning. as long as user actions are isolated and cannot impact mission critical applications, the agility and user empowerment may justify the risk of giving up control of release management. again, it is essential that in such a scenario, expiration timers are


##ing. as long as user actions are isolated and cannot impact mission critical applications, the agility and user empowerment may justify the risk of giving up control of release management. again, it is essential that in such a scenario, expiration timers are included to prevent server sprawl. the goal of access management is to make sure authorized users have access to the services they need while preventing access by unauthorized users. access management is the implementation of security policies defined by information security management at the service delivery layer. maintaining access for authorized users is critical for achieving the perception of continuous availability. besides allowing access, access management defines users who are allowed to use, configure, or administer objects in the management layer. from a provider ’ s perspective, it answers questions like : from a consumer ’ s perspective, it answers questions such as : access management is implemented at several levels and can include physical barriers to systems such as requiring access smartcards at the data center, or virtual barriers such as network and virtual local area network ( vlan ) separation, firewalling, and access to storage and applications. taking a service provider ’ s approach to access management will also make sure that resource segmentation and multi - tenancy is addressed. resource pools may need to be segmented to address security concerns around confidentiality, integrity, and availability. some tenants may not wish to share infrastructure resources to keep their environment isolated from others. access management of shared infrastructure requires logical access control mechanisms such as encryption, access control rights, user groupings, and permissions. dedicated infrastructure also relies on physical access control mechanisms, where infrastructure is not physically connected, but is effectively isolated through a firewall or other mechanisms. the goal of systems administration is to make sure that the daily, weekly, monthly, and as - needed tasks required to keep a system healthy are being performed. regularly performing ongoing systems administration tasks is critical for achieving predictability. as the organization matures and the knowledge management database becomes more robust and increasingly automated, systems administration tasks is no longer part of the job role function. it is important to keep this in mind as an organization moves to a private cloud. staff once responsible for systems administration should refocus on automation and scripting skills – and on monitoring the fabric to identify patterns that indicate possibilities for ongoing improvement of existing automated workflows.


published may 2008 properly located digital signage in high traffic areas on school campuses provides students and faculty with a convenient resource to stay up to date about the latest school news and activities. signage in education by anthony d. coppedge technology gets high marks. digital media and communications have come to play a vital role in people ’ s everyday lives, and a visit to the local k - 12 school, college or university campus quickly illustrates the many ways in which individuals rely on audio and visual technologies each day. the shift from analog media to digital, represented by milestones ranging from the replacement of the walkman by the mp3 player to the dtv transition currently enabling broadcasts beyond the home to mobile devices, has redefined the options that larger institutions, including those in our educational system, have for sharing information across the campus and facilities. flexible and efficient digital signage, in particular, is proving to be a flexible and efficient tool for delivering specific and up - to - date information within the educational environment. as a high - resolution, high - impact medium, it lives up to the now - widespread expectation that visual media be crisp and clear, displayed on a large screen. although the appeal of implementing digital signage networks does stem, in part, from plummeting screen prices and sophisticated content delivery systems, what ’ s equally or more important is that digital signage provides valuable information to the people who need it, when and where they need it. on school campuses — whether preschool, elementary, high school or post - secondary institutions — it does so effectively, for both educational purposes and for the security and safety of staff, administration and the student body as a whole. school campuses have begun leveraging digital signage technology in addition to, or in place of, printed material, such as course schedules, content and location ; time - sensitive school news and updates ; maps and directions ; welcome messages for visitors and applicants ; and event schedules. digital signage simplifies creation and delivery of multiple channels of targeted content to different displays on the network. although a display in the college admissions office might provide prospective students with a glimpse into student life, for example, another display outside a lab or seminar room might present the courses or lectures scheduled for that space throughout the day. this model of a distribution concept illustrates a school distributing educational content over a public tv broadcast network. at the k - 12 level, digital signage makes it easy to deliver information such as team or band practice schedules, or to post the cafeteria menu and give students information encouraging sound food choices. digital signage in the preschool and day


public tv broadcast network. at the k - 12 level, digital signage makes it easy to deliver information such as team or band practice schedules, or to post the cafeteria menu and give students information encouraging sound food choices. digital signage in the preschool and daycare setting makes it easy for teachers and caregivers to share targeted educational programming with their classes. among the most striking benefits of communicating through digital signage is the quality of the pictures and the flexibility with which images, text and video can be combined in one or more windows to convey information. studies have shown that dynamic signage is noticed significantly more often than are static displays and, furthermore, that viewers are more likely to remember that dynamic content. though most regularly updated digital signage content tends to be text - based, digital signage networks also have the capacity to enable the live campus - wide broadcast of key events : a speech by a visiting dignitary, the basketball team ’ s first trip to the state or national tournament, or even the proceedings at commencement and graduation. when time is short, it ’ s impractical to gather the entire student body in one place or there simply isn ’ t the time or means to deliver the live message in any other way. the ability to share critical information to the entire school community, clearly and without delay, has made digital signage valuable as a tool for emergency response and communications. parents, administrators, teachers and students today can ’ t help but be concerned about the school ’ s ability to respond quickly and effectively to a dangerous situation, whether the threat be from another person, an environmental hazard, an unpredictable weather system or some other menace. digital signage screens installed across a school campus can be updated immediately to warn students and staff of the danger, and to provide unambiguous instructions for seeking shelter or safety : where to go and what to do. although early digital signage systems relied on ip - based networks and point - to - point connections between a player and each display, current solutions operate on far less costly and much more scalable platforms. broadcast - based digital signage models allow content to be distributed remotely from a single data source via transport media, such as digital television broadcast, satellite, broadband and wimax. the staff member responsible for maintaining the digital signage network can use popular content creation toolsets to populate both dynamic and static displays. this content is uploaded to a server that, in turn, feeds the digital signage network via broadcast, much like datacasting, to the receive site for playout. by slotting specific content into predefined


both dynamic and static displays. this content is uploaded to a server that, in turn, feeds the digital signage network via broadcast, much like datacasting, to the receive site for playout. by slotting specific content into predefined display templates, each section with its own playlist, the administrator can schedule display of multiple elements simultaneously or a single - window static, video or animated display. the playlist enables delivery of the correct elements to the targeted display both at the scheduled time and in the appropriate layout. in networks with multicast - enabled routers, the administrator can schedule unique content for displays in different locations. in the case of delivering emergency preparedness or response information across a campus, content can be created through the same back - office software used for day - to - day digital signage displays. within the broadcast - based model, three components ensure the smooth delivery of content to each display. a transmission component serves as a content hub, allocating bandwidth and inserting content into the broadcast stream based on the schedule dictated by the network ’ s content management component. content is encapsulated into ip packets that, in turn, are encapsulated into mpeg2 packets for delivery. generic content distribution model for digital signage solution. the content management component of the digital signage network provides for organization and scheduling of content, as well as targeting of that content to specific receivers. flexibility in managing the digital signage system enables distribution of the same emergency message across all receivers and associated displays, or the delivery of select messages to particular displays within the larger network. with tight control over the message being distributed, school administrators can immediately provide the information that students and staff in different parts of the campus need to maintain the safest possible environment. receivers can be set to confirm receipt of content, in turn assuring administrative and emergency personnel that their communications are, in fact, being conveyed as intended. on the receiving end, the third component of the system, content, is extracted from the digital broadcast stream and fed to the display screen. the relationships that many colleges and universities share with public tv stations provide an excellent opportunity for establishing a digital signage network. today, the deployed base of broadcast - based content distribution systems in public tv stations is capable of reaching 50 % of the us population. these stations ’ dtv bandwidth is used not only for television programming, but also to generate new revenues and aggressively support public charters by providing efficient delivery of multimedia content for education, homeland security and other public services. educational institutions affiliated with such broadcasters already have


these stations ’ dtv bandwidth is used not only for television programming, but also to generate new revenues and aggressively support public charters by providing efficient delivery of multimedia content for education, homeland security and other public services. educational institutions affiliated with such broadcasters already have the technology, and much of the necessary infrastructure, in place to launch a digital signage network. in taking advantage of the public broadcaster ’ s content delivery system, the college or university also can tap into the station ’ s existing links with area emergency response agencies. as digital signage technology continues to evolve, educational institutions will be able to extend both urgent alerts and more mundane daily communications over text and email messaging. smart content distribution systems will push consistent information to screens of all sizes, providing messages not only to displays, but also to the cell phones and pdas so ubiquitous in us schools. the continued evolution of mph technology will support this enhancement in delivery of messages directly to each student. mph in - band mobile dtv technology leverages atsc dtv broadcasts to enable extensions of digital signage and broadcast content directly to personal devices, whether stationary or on the move. rather than rely on numerous unrelated systems, such as ringing bells, written memos and intercom announcements, schools can unify messaging and its delivery, in turn reducing the redundancy involved in maintaining communications with the student body. an effective digital signage network provides day - to - day benefits for an elementary school, high school, college or university while providing invaluable emergency communications capabilities that increasingly are considered a necessity, irrespective of whether they get put to the test. the selection of an appropriate digital signage model depends, of course, on the needs of the organization. educational institutions share many of the same concerns held by counterparts in the corporate world, and key among those concerns is the simple matter of getting long - term value and use out of their technical investments. however, before even addressing the type of content the school wishes to create and distribute, the systems integrator, consultant or other av and media professional should work with the eventual operators of the digital signage network to identify and map out the existing workflow. once the system designer, integrator or installer has evaluated how staff currently work in an emergency to distribute information, he then can adjust established processes and adapt them to the digital signage model. the administrative staff who will be expected to update or import schedules to the digital signage system will have a much lower threshold of acceptance for a workflow that is completely unfamiliar or at odds with all their previous experience.


adapt them to the digital signage model. the administrative staff who will be expected to update or import schedules to the digital signage system will have a much lower threshold of acceptance for a workflow that is completely unfamiliar or at odds with all their previous experience. an intuitive, easy - to - use system is more likely to be used in an emergency if it has become familiar in everyday practice. turnkey digital signage solutions provide end - to - end functionality without forcing users and integrators to work with multiple systems and interfaces. the key in selecting a vendor lies in ensuring that they share the same vision and are moving in the same direction as the end user. in addition to providing ease of use, digital signage solutions for the education market also must provide a high level of built - in security, preventing abuse or misuse by hackers, or by those without the knowledge, experience or authority to distribute content over the network. because the network is a conduit for emergency messaging, its integrity must be protected. so, the installer must not only identify the number of screens to be used and where, but also determine who gets access to the system and how that access remains secure. scalable systems that can grow in number of displays or accommodate infrastructure improvements and distribution of higher - bandwidth content will provide the long - term utility that makes the investment worthwhile. by going into the project with an understanding of existing infrastructure, such as cabling, firewalls, etc., and the client ’ s goals, the professional is equipped to advise the customer as to the necessity, options and costs for enhancing or improving on that infrastructure. as with any other significant deployment of av technology, the installation of a digital signage network also requires knowledge of the site, local building codes, the availability of power and so forth. ralph bachofen, senior director of product management and marketing, triveni digital, has more than 15 years of experience in voice and multimedia over internet protocol ( ip ), telecommunications and the semiconductor business. the infrastructure requirements of a school in deploying a digital signage network will vary, depending on the type of content being delivered through the system. hd and streaming content clearly are bandwidth hogs, whereas tickers and other text - based messages put a low demand on bandwidth. most facilities today are equipped with gigabit ethernet networks that can handle the demands of live video delivery and lighter content. however, even bandwidth - heavy video can be delivered by less robust networks, as larger clips can be “ trickled ” over time to the


today are equipped with gigabit ethernet networks that can handle the demands of live video delivery and lighter content. however, even bandwidth - heavy video can be delivered by less robust networks, as larger clips can be “ trickled ” over time to the site, as long as storage on the unit is adequate. there is no set standard for the bandwidth required, just as there is no single way to use a digital signage solution. it all depends on how the system will be used, and that ’ s an important detail to address up front. most digital signage solutions feature built - in content - creation tools and accept content from third - party applications, as well. staff members who oversee the system thus can use familiar applications to create up - to - date content for the school ’ s digital signage network. this continuity in workflow adds to the value and efficiency of the network in everyday use, reducing the administrative burden while serving as a safeguard in the event of an emergency. for educational institutions, the enormous potential of the digital signage network can open new doors for communicating with students and staff, but only if it is put to use effectively. comprehensive digital signage solutions offer ease of use to administration, deliver clear and useful messaging on ordinary days and during crises, and feature robust design and underlying technology that supports continual use well into the future.


how we found the missing memristor the memristor - - the functional equivalent of a synapse - - could revolutionize circuit design image : bryan christie design thinking machine this artist ' s conception of a memristor shows a stack of multiple crossbar arrays, the fundamental structure of r. stanley williams ' s device. because memristors behave functionally like synapses, replacing a few transistors in a circuit with memristors could lead to analog circuits that can think like a human brain. it ’ s time to stop shrinking. moore ’ s law, the semiconductor industry ’ s obsession with the shrinking of transistors and their commensurate steady doubling on a chip about every two years, has been the source of a 50 - year technical and economic revolution. whether this scaling paradigm lasts for five more years or 15, it will eventually come to an end. the emphasis in electronics design will have to shift to devices that are not just increasingly infinitesimal but increasingly capable. earlier this year, i and my colleagues at hewlett - packard labs, in palo alto, calif., surprised the electronics community with a fascinating candidate for such a device : the memristor. it had been theorized nearly 40 years ago, but because no one had managed to build one, it had long since become an esoteric curiosity. that all changed on 1 may, when my group published the details of the memristor in nature. combined with transistors in a hybrid chip, memristors could radically improve the performance of digital circuits without shrinking transistors. using transistors more efficiently could in turn give us another decade, at least, of moore ’ s law performance improvement, without requiring the costly and increasingly difficult doublings of transistor density on chips. in the end, memristors might even become the cornerstone of new analog circuits that compute using an architecture much like that of the brain. for nearly 150 years, the known fundamental passive circuit elements were limited to the capacitor ( discovered in 1745 ), the resistor ( 1827 ), and the inductor ( 1831 ). then, in a brilliant but underappreciated 1971 paper, leon chua, a professor of electrical engineering at the university of california, berkeley, predicted the existence of a fourth fundamental device, which he called a memristor. he proved that memristor behavior could not be duplicated by any circuit built using only the


professor of electrical engineering at the university of california, berkeley, predicted the existence of a fourth fundamental device, which he called a memristor. he proved that memristor behavior could not be duplicated by any circuit built using only the other three elements, which is why the memristor is truly fundamental. memristor is a contraction of ” memory resistor, ” because that is exactly its function : to remember its history. a memristor is a two - terminal device whose resistance depends on the magnitude and polarity of the voltage applied to it and the length of time that voltage has been applied. when you turn off the voltage, the memristor remembers its most recent resistance until the next time you turn it on, whether that happens a day later or a year later. think of a resistor as a pipe through which water flows. the water is electric charge. the resistor ’ s obstruction of the flow of charge is comparable to the diameter of the pipe : the narrower the pipe, the greater the resistance. for the history of circuit design, resistors have had a fixed pipe diameter. but a memristor is a pipe that changes diameter with the amount and direction of water that flows through it. if water flows through this pipe in one direction, it expands ( becoming less resistive ). but send the water in the opposite direction and the pipe shrinks ( becoming more resistive ). further, the memristor remembers its diameter when water last went through. turn off the flow and the diameter of the pipe ” freezes ” until the water is turned back on. that freezing property suits memristors brilliantly for computer memory. the ability to indefinitely store resistance values means that a memristor can be used as a nonvolatile memory. that might not sound like very much, but go ahead and pop the battery out of your laptop, right now — no saving, no quitting, nothing. you ’ d lose your work, of course. but if your laptop were built using a memory based on memristors, when you popped the battery back in, your screen would return to life with everything exactly as you left it : no lengthy reboot, no half - dozen auto - recovered files. but the memristor ’ s potential goes far beyond instant - on computers to embrace one of the grandest technology challenges : mimicking the functions of a brain. within a decade, memristors could let us emulate


recovered files. but the memristor ’ s potential goes far beyond instant - on computers to embrace one of the grandest technology challenges : mimicking the functions of a brain. within a decade, memristors could let us emulate, instead of merely simulate, networks of neurons and synapses. many research groups have been working toward a brain in silico : ibm ’ s blue brain project, howard hughes medical institute ’ s janelia farm, and harvard ’ s center for brain science are just three. however, even a mouse brain simulation in real time involves solving an astronomical number of coupled partial differential equations. a digital computer capable of coping with this staggering workload would need to be the size of a small city, and powering it would require several dedicated nuclear power plants. memristors can be made extremely small, and they function like synapses. using them, we will be able to build analog electronic circuits that could fit in a shoebox and function according to the same physical principles as a brain. a hybrid circuit — containing many connected memristors and transistors — could help us research actual brain function and disorders. such a circuit might even lead to machines that can recognize patterns the way humans can, in those critical ways computers can ’ t — for example, picking a particular face out of a crowd even if it has changed significantly since our last memory of it. the story of the memristor is truly one for the history books. when leon chua, now an ieee fellow, wrote his seminal paper predicting the memristor, he was a newly minted and rapidly rising professor at uc berkeley. chua had been fighting for years against what he considered the arbitrary restriction of electronic circuit theory to linear systems. he was convinced that nonlinear electronics had much more potential than the linear circuits that dominate electronics technology to this day. chua discovered a missing link in the pairwise mathematical equations that relate the four circuit quantities — charge, current, voltage, and magnetic flux — to one another. these can be related in six ways. two are connected through the basic physical laws of electricity and magnetism, and three are related by the known circuit elements : resistors connect voltage and current, inductors connect flux and current, and capacitors connect voltage and charge. but one equation is missing from this group : the relationship between charge moving through a circuit and the magnetic flux surrounded by that circuit — or more subtly, a mathematical doppelganger defined by faraday ’


and capacitors connect voltage and charge. but one equation is missing from this group : the relationship between charge moving through a circuit and the magnetic flux surrounded by that circuit — or more subtly, a mathematical doppelganger defined by faraday ’ s law as the time integral of the voltage across the circuit. this distinction is the crux of a raging internet debate about the legitimacy of our memristor [ see sidebar, ” resistance to memristance ” ]. chua ’ s memristor was a purely mathematical construct that had more than one physical realization. what does that mean? consider a battery and a transformer. both provide identical voltages — for example, 12 volts of direct current — but they do so by entirely different mechanisms : the battery by a chemical reaction going on inside the cell and the transformer by taking a 110a ¿ ¿ v ac input, stepping that down to 12 v ac, and then transforming that into 12 v dc. the end result is mathematically identical — both will run an electric shaver or a cellphone, but the physical source of that 12 v is completely different. conceptually, it was easy to grasp how electric charge could couple to magnetic flux, but there was no obvious physical interaction between charge and the integral over the voltage. chua demonstrated mathematically that his hypothetical device would provide a relationship between flux and charge similar to what a nonlinear resistor provides between voltage and current. in practice, that would mean the device ’ s resistance would vary according to the amount of charge that passed through it. and it would remember that resistance value even after the current was turned off. he also noticed something else — that this behavior reminded him of the way synapses function in a brain. even before chua had his eureka moment, however, many researchers were reporting what they called ” anomalous ” current - voltage behavior in the micrometer - scale devices they had built out of unconventional materials, like polymers and metal oxides. but the idiosyncrasies were usually ascribed to some mystery electrochemical reaction, electrical breakdown, or other spurious phenomenon attributed to the high voltages that researchers were applying to their devices. as it turns out, a great many of these reports were unrecognized examples of memristance. after chua theorized the memristor out of the mathematical ether, it took another 35 years for us to intentionally build the device at hp labs, and we only really understood the device about two years ago


examples of memristance. after chua theorized the memristor out of the mathematical ether, it took another 35 years for us to intentionally build the device at hp labs, and we only really understood the device about two years ago. so what took us so long? it ’ s all about scale. we now know that memristance is an intrinsic property of any electronic circuit. its existence could have been deduced by gustav kirchhoff or by james clerk maxwell, if either had considered nonlinear circuits in the 1800s. but the scales at which electronic devices have been built for most of the past two centuries have prevented experimental observation of the effect. it turns out that the influence of memristance obeys an inverse square law : memristance is a million times as important at the nanometer scale as it is at the micrometer scale, and it ’ s essentially unobservable at the millimeter scale and larger. as we build smaller and smaller devices, memristance is becoming more noticeable and in some cases dominant. that ’ s what accounts for all those strange results researchers have described. memristance has been hidden in plain sight all along. but in spite of all the clues, our finding the memristor was completely serendipitous. in 1995, i was recruited to hp labs to start up a fundamental research group that had been proposed by david packard. he decided that the company had become large enough to dedicate a research group to long - term projects that would be protected from the immediate needs of the business units. packard had an altruistic vision that hp should ” return knowledge to the well of fundamental science from which hp had been withdrawing for so long. ” at the same time, he understood that long - term research could be the strategic basis for technologies and inventions that would directly benefit hp in the future. hp gave me a budget and four researchers. but beyond the comment that ” molecular - scale electronics ” would be interesting and that we should try to have something useful in about 10 years, i was given carte blanche to pursue any topic we wanted. we decided to take on moore ’ s law. at the time, the dot - com bubble was still rapidly inflating its way toward a resounding pop, and the existing semiconductor road map didn ’ t extend past 2010. the critical feature size for the transistors on an integrated circuit was 350 nanometers ; we had a long way to go before atomic sizes would become a


resounding pop, and the existing semiconductor road map didn ’ t extend past 2010. the critical feature size for the transistors on an integrated circuit was 350 nanometers ; we had a long way to go before atomic sizes would become a limitation. and yet, the eventual end of moore ’ s law was obvious. someday semiconductor researchers would have to confront physics - based limits to their relentless descent into the infinitesimal, if for no other reason than that a transistor cannot be smaller than an atom. ( today the smallest components of transistors on integrated circuits are roughly 45 nm wide, or about 220 silicon atoms. ) that ’ s when we started to hang out with phil kuekes, the creative force behind the teramac ( tera - operation - per - second multiarchitecture computer ) — an experimental supercomputer built at hp labs primarily from defective parts, just to show it could be done. he gave us the idea to build an architecture that would work even if a substantial number of the individual devices in the circuit were dead on arrival. we didn ’ t know what those devices would be, but our goal was electronics that would keep improving even after the devices got so small that defective ones would become common. we ate a lot of pizza washed down with appropriate amounts of beer and speculated about what this mystery nanodevice would be. we were designing something that wouldn ’ t even be relevant for another 10 to 15 years. it was possible that by then devices would have shrunk down to the molecular scale envisioned by david packard or perhaps even be molecules. we could think of no better way to anticipate this than by mimicking the teramac at the nanoscale. we decided that the simplest abstraction of the teramac architecture was the crossbar, which has since become the de facto standard for nanoscale circuits because of its simplicity, adaptability, and redundancy. the crossbar is an array of perpendicular wires. anywhere two wires cross, they are connected by a switch. to connect a horizontal wire to a vertical wire at any point on the grid, you must close the switch between them. our idea was to open and close these switches by applying voltages to the ends of the wires. note that a crossbar array is basically a storage system, with an open switch representing a zero and a closed switch representing a one. you read the data by probing the switch with a small voltage. like everything else at the nanoscale, the switches