election 2012 roundup : four faculty members on this year ' s campaign henry and gertrude rothschild professor of computer science q. tell us about your project and how it relates to the election. over the course of the last year, we have been collecting data from online political forums, twitter and different kinds of online discussions. we have also collected news. the program we have created identifies influencers. we look to identify who was able to change people ’ s minds and how ; where sentiment shifted ; and what arguments people found persuasive. and we look to correlate shifts in sentiment with events as reported in the news. q. how does it work? the systems detect influence using several programs that perceive components of influence. for example, one program can detect in online discussions whether a participant feels positively, negatively or neutral towards a topic and whether other people on the forum agree or disagree. we use machine - learned algorithms that recognize sentiment based on the way language is used — for instance, negative or positive expressions such as “ i like ” or “ i hate. ” the computer uses all of these cues to identify that this person is in favor of a particular claim or this other person is opposed. we have another algorithm that can detect whether someone is making a claim about a particular topic. and we can detect when someone is attempting to persuade people to go along with their opinion. then we can look at how those arguments change the sentiment of others or the direction of the conversation. when we put them all together, we can determine whether somebody is being influential and when they change other people ’ s opinions. we are still building these systems and plan to look at other kinds of information, such as age and gender. q. how would this relate to the national discourse? we might use it to analyze how people reacted to particular events, which events were important in determining opinions, and how in online social media, influence played a role in determining outcomes. so we might look at whether changes in opinion are correlated to a particular event in the news, like the recent attack in libya. there might be a discussion about health care on a forum, and you might have two people taking different sides about whether obamacare is helpful or not. by looking at what claims are made and who agrees or disagrees, we can identify whether one person was able to influence other people. also, we can look at the influence of obama or people who work for him, what they are reported to have said, how often it was mentioned in the forums and what effect that had


can identify whether one person was able to influence other people. also, we can look at the influence of obama or people who work for him, what they are reported to have said, how often it was mentioned in the forums and what effect that had on people ’ s sentiments. i would note that our programs are not perfect, they have error rates. these are hard problems, and they are not easily solved. our error rates can go from 10 to 30 percent depending on the component and the data. q. what is your overall goal? ultimately, we want to be looking across quite a few forums to see what is happening. we can aggregate that information to find out how influence is expressed in different genres, which forums are most influential, how influences changes over time, who within a forum is most influential and how do they get people to agree. ultimately, we want to be able to detect influence for a variety of purposes such as advertising or online problem solving. q. how did you get interested in this field? i did my undergrad at brown in comparative literature. so i had an interest in language at that point. i did both french and english, and looked at all time periods. i loved james joyce and baudelaire. a lot of my friends were doing computer science and were very enthusiastic about it. so towards my senior year i began taking course in computer science. i learned at the end of undergraduate that there was a field where you could combine computers and language. i heard university of pennsylvania had a great program in it, and i went there to do a phd with aravind joshi one of the pioneers in the field of natural language processing. — interview by adam piore four columbia faculty were awarded sloan research fellowships by the alfred p. sloan foundation. they are mark churchland, assistant professor of neuroscience ; wei min, assistant professor of chemistry ; simha sethumadhavan, associate professor of computer science ; and wei zhang, assistant professor of mathematics. alondra nelson, associate professor of sociology, won the 2012 book award from the association for humanist sociology for body and soul : the black panther party and the fight against medical discrimination.


modelling southern ocean krill population dynamics : biological processes generating fluctuations in the south georgia ecosystem murphy, eugene j. ; reid, keith. 2001 modelling southern ocean krill population dynamics : biological processes generating fluctuations in the south georgia ecosystem. marine ecology progress series, 217. 175 - 189. 10. 3354 / meps217175full text not available from this repository. variability is a key feature of the pelagic ecosystems of the southern ocean and an important aspect of the variation is fluctuation in the abundance of krill euphausia superba dana, the major prey item of many of the higher predators. direct impacts of variability in the large - scale physical environment, such as changes in ocean circulation, have been suggested as the main factor generating the observed fluctuations. so far, however, there has been little quantitative assessment of the importance of krill population dynamics in the observed variation. here, analyses of a model of krill population development and predator diet data from south georgia have been used to examine seasonal changes in the population structure of krill. the krill population model was combined with a size - based selection function and used to generate expected length - frequency distributions in the predator diet through a summer season. comparison of the model solutions with the predator diet data indicates that the model can reproduce the observed pattern of variation and emphasizes that adult population changes are a key aspect of the interannual fluctuations observed during some years. low krill abundance was associated with reduced representation of the 3 + age group ( 3 to 4 yr old ), whereas when krill were abundant the 3 + age class was the major age group present. the seasonal changes in the population structure in the predator diet involve a complex interaction of relative year class strength, timing of immigration, fluctuations in growth rates and dynamic predatorselective effects. development of the model to examine the interactive effects of changing krill growth and mortality rates will be a valuable next step. the dominance of the changes in krill population age structure underlines the fact that to understand the variability of the south georgia ecosystem we must identify the major factors generating variability in population dynamics throughout the scotia sea. | programmes : | | bas programmes > antarctic science in the global context ( 2000 - 2005 ) > dynamics and management of ocean ecosystems | | additional keywords : | | ecosystem, krill, ocean, model, population dynamics, predators, diet data, interannual, variability, allochthonous, southern ocean | | date made live : | | 24 oct 2012 12 : 49 |


them. tell everyone you know that " lookup " is not a verb. you will make a pedant ( me ) happy. you will earn the respect of grammar nazis. most importantly, you will know the truth. magnanimousness demands that i offer solutions, or correct forms of some of the common abuses of " lookup " here are some suggestions, assuming you prefer " lookup " as a word rather than take a more conservative approach and insist the proper form is " look up " or " look - up. " | can you lookup? | | can you look up? | | i tried to lookup.... | | i tried to look up.... | | enter your name at the lookup prompt. | | ( this is acceptable ) | | please lookup again. | | please look up again. | you can also continue your education by learning about other words that are not verbs. for entertainment you can read a sarcastic rebuttal to the argument that lookup really is a verb and the language simply has evolved. thanks to mark pettit for the corrections to the " checkout " page. thanks to nathanial jones for the observation of phrasal verbs. thanks to someone whose email i deleted before i could record his name for his suggestion to add a note on prepositions. thanks to john goodman for the correction on " carryout " in the index.


skip over navigation guide and features guide and features science, technology, engineering and mathematics featured early years foundation stage ; us kindergarten featured uk key stage 1 & 2 ; us grades 1 - 4 featured uk key stage 3 - 5 ; us grades 5 - 12 featured uk key stage 1, us grade 1 & 2 featured uk key stage 2 ; us grade 3 & 4 featured uk key stages 3 & 4 ; us grade 5 - 10 featured uk key stage 4 & 5 ; us grade 11 & 12 what ' s to notice? stage : 1, 2, 3, 4 and 5 article by lynne mcclure the theme for is about ' actions on objects '. all of the activities we have devised involve some kind of noticing, and several of them involve new interactivities which we think promote lots of opportunities to notice. john mason, our guest editor this month, has written a lot about the ' discipline of noticing ' and how important it is to the understanding of the deeper structures of mathematics. so what does this mean and how can we help our students get better at it - how can we ' educate awareness '? rather than think abstractly about this, let ' s consider what it looks like in some of this month ' s offerings. add and take - away path can be construed as an exercise in adding up and taking away. one might also think of it as a very early introduction to vectors. but the task has been devised so that the problem solver is almost forced to notice something. perhaps two totals being the same might be a coincidence, but if the children are encouraged to try some others they notice that so long as they fix the start and end of a path, the total will always be the same. to adults that may be obvious but to small children it is far from being so and they can be quite surprised. the teacher ' s role here is in offering a structured task which has lots of flexibility so that the children can choose any routes they like. and then the big question - what do they notice and why do they think this happened? i really like area and perimeter. children so often get these muddled up, usually because they meet them at different times in their school career, so setting a task where they intentionally have to attend to both simultaneously is a good way of confronting the confusion. the usual questions students are asked are about knowing a formula and calculating the value of either area or perimeter but here the questions are of a different nature. they force the child to look at the relationship between the shape, its


way of confronting the confusion. the usual questions students are asked are about knowing a formula and calculating the value of either area or perimeter but here the questions are of a different nature. they force the child to look at the relationship between the shape, its area and its perimeter. long thin shapes may have a small area and a large perimeter for example ; shapes with bits cut out may have a very small area and a very big perimeter - so the structure and property of the shape itself become the important ideas. and the variants can be used as consolidation games. in each case the students have to notice the commonalities, framed in the multiplication operation, so that they can deduce what whole number factors go where. similar noticings have to take place in. because many of the questions differ only slightly, asking which piece of the answer gives the most information demands noticing, which leads to a clearer understanding of the structure of the question. whilst i was focused on this, two activities from previous months came to mind. is a task we published last month. the team have been using it a lot with students recently ( you can see videos of this ), and have refined their thinking about how it might be used, and the sorts of questions to ask. the students are invited to perform a certain action ( tilting a square ) and asked what they notice. the teacher ' s role is in helping them to attend to similarities and differences - and in this case the way that these are recorded by the teacher on the board helps the students to notice in a way that they may not have done if they had recorded in other ways. one of my favourite tools on the nrich site is you ' ll need to read the instructions first, but as an interactivity to model actions, and successive actions, on objects, it ' s an engaging option. lots of deciding what to attend to and how to record it. in all of these tasks - and the others this month - ' actions on objects ' change something. learners get caught up in the detective work of trying to fathom what it is that makes a difference, and sometimes whether the order of actions matters. if you ' re short of something to do and want to refine your own noticing skill, try 18 - hole light golf. it could become addictive. meet the team the nrich project aims to enrich the mathematical experiences of all learners. to support this aim, members of the nrich team work in a wide range of capacities, including providing professional development for teachers wishing to embed


with " serious " ) is a mythical greek god with a fish - tail and a man ' s torso. the vehicle was named in a nationwide contest open to high school and college students. the mariana trench forms the boundary between two tectonic plates, where the pacific plate is subducted beneath the small mariana plate. it is part of the pacific ring of fire, a 40, 000 - kilometer ( 25, 000 - mile ) area where most of the world ' s volcanic eruptions and earthquakes occur. at 11, 000 meters, its depth is about the height a commercial airliner flies. to reach the trench, nereus dove nearly twice as deep as research submarines are capable of, and had to withstand pressures 1, 000 times that at earth ' s surface - - crushing forces similar to those on the surface of venus, according to dana yoerger of whoi and louis whitcomb of johns hopkins university, who developed the vehicle ' s navigation and control system and conducted successively deeper dives to test nereus. " we couldn ' t be prouder of the stunning accomplishments of this dedicated and talented team, " said susan avery, president and director of whoi. " with this engineering trial successfully behind us, we ' re eager for nereus to become widely used to explore the most inaccessible reaches of the ocean. with no part of the deep seafloor beyond our reach, it ' s exciting to think of the discoveries that await. " only two other vehicles have succeeded in reaching the mariana trench : the u. s. navy - built bathyscaphe trieste, which carried jacques piccard and don walsh there in 1960, and the japanese - built robot kaiko, which made three unmanned expeditions to the trench between 1995 and 1998. trieste was retired in 1966 and kaiko was lost at sea in 2003. the nereus engineering team believed that a tethered robot using traditional technologies would be prohibitively expensive to build and operate. so they used unique technologies and innovative methods to strike a balance between size, weight, materials cost and functionality. building on previous experience developing tethered robots and autonomous underwater vehicles ( auvs ), the team fused the two approaches together to develop a hybrid vehicle that could fly like an aircraft to survey and map broad areas, then be converted quickly into a remotely operated vehicle ( rov ) that can hover like a helicopter near the seafloor to conduct experiments or to collect biological or rock samples. the tethering system presented one of the greatest challenges in developing a cost - effective ro


into a remotely operated vehicle ( rov ) that can hover like a helicopter near the seafloor to conduct experiments or to collect biological or rock samples. the tethering system presented one of the greatest challenges in developing a cost - effective rov capable of reaching these depths. traditional robotic systems use a steel - reinforced cable made of copper to power the vehicle, and optical fibers to enable information to be passed between the ship and the vehicle. if such a cable were used to reach the mariana trench, it would snap under its own weight before it reached that depth. to solve this challenge, the nereus team adapted fiber - optic technology developed by the navy ' s space and naval warfare systems center pacific to carry real - time video and other data between the nereus and the surface crew. similar in diameter to a human hair and with a breaking strength of only eight pounds, the tether is composed of glass fiber with a very thin protective jacket of plastic. nereus brings approximately 40 kilometers ( 25 miles ) of cable in two canisters the size of large coffee cans that spool out the fiber as needed. by using this very slender tether instead of a large cable, the team was able to decrease the size, weight, complexity and cost of the vehicle. another weight - saving advance of the vehicle is its use of ceramic spheres for flotation, rather than the much heavier traditional syntactic foam used on vehicles like the submersible alvin or the rov jason. each of nereus ' s two hulls contains between 700 and 800 of the 9 - centimeter ( 3. 5 - inch ) hollow spheres that are precisely designed and fabricated to withstand crushing pressures. whoi engineers also developed a hydraulically operated, lightweight robotic manipulator arm that could operate under intense pressure. with its tandem hull design, nereus weighs nearly 3 tons in air and is about 4. 25 meters ( 14 feet ) long and approximately 2. 3 meters ( nearly 8 feet ) wide. it is powered by more than 4, 000 lithium - ion batteries. they are similar to those used in laptop computers and cell phones, but have been carefully tested to be used safely and reliably under the intense pressure of the depths. " these and future discoveries by nereus will be the result of its versatility and agility - - it ' s like no other deep submergence vehicle, " said tim shank, a biologist at whoi who is aboard the expedition. " it allows vast areas to be explored with great


sparks - st. elmo ' s fire instructor / speaker : prof. walter lewin last time i mentioned to you that charge resides at the surface of solid conductors but that it ' s not uniformly distributed. perhaps you remember that, unless it happens to be a sphere. and i want to pursue that today. if i had a solid conductor which say had this shape and i ' m going to convince you today that right here, the surface charge density will be higher than there. because the curvature is stronger than it is here. and the way i want to approach that is as follows. suppose i have here a solid conductor a which has radius r of a and very very far away, maybe tens of meters away, i have a solid conductor b with radius r of b and they are connected through a conducting wire. if they are connected through a conducting wire, then it ' s equipotential. they all have the same potential. i ' m going to charge them up until i get a charge distribution qa here and i get qb there. the potential of a is about the same that it would be if b were not there. because b is so far away that if i come with some charge from infinity in my pocket that the work that i have to do to reach a per unit charge is independent of whether b is there or not, because b is far away, tens of meters, if you can make it a mile if you want to. and so the potential of a is then the charge on a divided by 4 pi epsilon 0 the radius of a. but since it is an equipotential because it ' s all conducting, this must be also the potential of the sphere b, and that is the charge on b divided by 4 pi epsilon 0 r of b. and so you see immediately that the q, the charge on b, divided by the radius of b, is the charge on a divided by the radius on a. and if the radius of b were for instance 5 times larger than the radius of a, there would be 5 times more charge on b than there would be on a. but if b has a 5 times larger radius, then its surface area is 25 times larger and since surface charge density, sigma, is the charge on a sphere divided by the surface area of the sphere, it is now clear that if the radius of b is 5 times larger than a, it ' s true that the charge on b is 5 times the charge on a, but the surface charge density on b is


by the surface area of the sphere, it is now clear that if the radius of b is 5 times larger than a, it ' s true that the charge on b is 5 times the charge on a, but the surface charge density on b is now only one - fifth of the surface charge density of a because its area is 25 times larger and so you have this - - the highest surface charge density at a than you have at b. 5 times higher surface charge density here than there. and i hope that convinces you that if we have a solid conductor like this, even though it ' s not ideal as we have here with these two spheres far apart, that the surface charge density here will be larger than there because it has a smaller radius. it ' s basically the same idea. and so you expect the highest surface charge density where the curvature is the highest, smallest radius, and that means that also the electric field will be stronger there. that follows immediately from gauss ' s law. if this is the surface of a conductor, any conductor, a solid conductor, where the e field is 0 inside of the conductor, and there is surface charge here, what i ' m going to do is i ' m going to make a gaussian pillbox, this surface is parallel to the conductor, i go in the conductor, and this now is my gaussian surface, let this area be capital a, and let ' s assume that it is positive charge so that the electric field lines come out of the surface like so, perpendicular to the surface. always perpendicular to equipotential, so now if i apply gauss ' s law which tells me that the surface integral of the electric flux throughout this whole surface, well, there ' s only flux coming out of this surface here, i can bring that surface as close to the surface as i want to. i can almost make it touch the conductor. so everything comes out only through this surface, and so what comes out is the surface area a times the electric field e. the a and e are in the same direction, because remember e is perpendicular to the surface of the equipotentials. and so this is all there is for the surface integral, and that is all the charge inside, well the charge inside is of course the surface charge density times the area a, divided by epsilon 0, this is gauss ' s law. and so you find immediately that the electric field is sigma divided by epsilon 0. so whenever you have a conductor if you


inside is of course the surface charge density times the area a, divided by epsilon 0, this is gauss ' s law. and so you find immediately that the electric field is sigma divided by epsilon 0. so whenever you have a conductor if you know the local surface charge density you always know the local electric field. and since the surface charge density is going to be the highest here, even though the whole thing is an equipotential, the electric field will also be higher here than it will be there. i can demonstrate this to you in a very simple way. i have here a cooking pan and the cooking pan, i used to boil lobsters in there, it ' s a large pan. the cooking pan i ' m going to charge up and the cooking pan here has a radius, whatever it is, maybe 20 centimeters, but look here at the handle, how very small this radius is, so you could put charge on there and i ' m going to convince you that i can scoop off more charge here where the radius is small than i can scoop off here. i have here a small flat spoon and i ' m going to put the spoon here on the surface here and on the surface there and we ' re going to see from where we can scoop off the most charge. still charged from the previous lecture. so here, we see the electroscope that we have seen before. i ' m going to charge this cooking pan with my favorite technique which is the electrophorus. so we have the cat fur and we have the glass plate. i ' m going to rub this first with the cat fur, put it on, put my finger on, get a little shock, charge up the pan, put my finger on, get another shock, charge up the pan, and another one, charge up the pan, make sure that i get enough charge on there, rub the glass again, put it on top, put my finger on, charge, once more, and once more. let ' s assume we have enough charge on there now. here is my little spoon. i touch here the outside here of the can - - of the pan. and go to the electroscope and you see a little charge. it ' s very clear. what i want to show you now it ' s very qualitative is that when i touch here the handle, it ' s a very small radius, that i can take off more charge. there we go. that ' s all i wanted to show you. so you


you now it ' s very qualitative is that when i touch here the handle, it ' s a very small radius, that i can take off more charge. there we go. that ' s all i wanted to show you. so you ' ve seen now in front of your own eyes for the first time that even though this is a conductor that means that it is an equipotential, that the surface charge density right - - right here is higher than the surface charge density here. only if it is a sphere of course for circle symmetry reasons will the charge be uniformly distributed. if the electric field becomes too high we get what we call electric breakdown. we get a discharge into the air. and the reason for that is actually quite simple. if i have an electron here and this is an electric field, the electron will start to accelerate in this direction. the electron will collide with nitrogen and oxygen molecules in the air and if the electron has enough kinetic energy to ionize that molecule then one electron will become two electrons. the original electron plus the electron from the ion. and if these now start to accelerate in this electric field, and if they collide with the molecules, and if they make an ion, then each one will become two electrons, and so you get an avalanche. and this avalanche is an electric breakdown and you get a spark. when the ions that are formed become neutral again they produce light and that ' s what you see. that ' s the light that you see in the spark. and so sparks will occur typically at the - - at sharp points - - at areas where the curvature is strong, whereby the radius is very small, that ' s where the electric fields are the highest. how strong should the electric field be? well, we can make a back of the envelope calculation. if you take air of 1 atmosphere, dry air, at room temperature, then the - - the electron on average, on average, will have to travel about 1 micron, which is 10 to the - 6 meters, between the collisions with the molecules, it ' s just a given. sometimes a little more, sometimes a little less. because it ' s a random process of course. to ionize nitrogen, to ionize oxygen, takes energy. to ionize an oxygen molecule takes twelve - and - a - half electron volts. and to ionize nitrogen takes about 15 electron volts. what is an electron volt? well, an electron volt is a teeny weeny little amount


ionize an oxygen molecule takes twelve - and - a - half electron volts. and to ionize nitrogen takes about 15 electron volts. what is an electron volt? well, an electron volt is a teeny weeny little amount of energy. it ' s 1. 6 times 10 to the - 19 joules. electron volt is actually a very nice unit of energy. because once you have an electron and it moves over a potential difference of one volt, it gains in kinetic energy, that ' s the definition of an electron volt, it gains 1 electron volt. it ' s the charge of the electron, which is 1. 6 times 10 to the - 19 coulombs, multiplied by 1 volt. and that gives you then the energy, 1 electron volt. and so what it means then - - let ' s assume that this number is 10 electron volts. we only want a back of the envelope calculation. so we want the electron to move over a potential difference delta v which is roughly 10 volts and we want it to do that over a distance delta x which is 10 to the - 6 meters, that ' s your 1 micron. and if that happens you ' ll get this enough kinetic energy in the electron to cause an ion. so what electric field is required for that, that is delta v, the potential difference, divided by the delta x, so that is 10 divided by 10 to the - 6, so that ' s about 10 to the 7 volts per meter. that ' s a very strong electric field. in reality when we measure the electric fields near breakdown, it is more like 3 million volts per meter. but it ' s still very close. this was only a back of the envelope calculation. so very roughly at 1 atmosphere air, room temperature, when the air is dry, we get electric breakdown at about 3 million volts per meter. when the ions neutralize you see light, that ' s why sparks can be seen. they heat the air, they produce a little pressure wave, so you can also hear noise. if you had two parallel plates and you would bring those plates closely together and suppose they had a potential difference of 300 volts, then you would reach an electric field of 3 million volts per meter when the distance d is about one tenth of a millimeter. so that ' s when you expect spontaneous discharge between these two plates. in practice however it probably will happen when the plates are further apart than one


field of 3 million volts per meter when the distance d is about one tenth of a millimeter. so that ' s when you expect spontaneous discharge between these two plates. in practice however it probably will happen when the plates are further apart than one tenth of a millimeter. and the reason for that is that there is no such thing as perfect plates. the plates have imperfections. that means there are always areas on the plate which are not flat, which are a little bit like what you see there, small radius, and that ' s of course where the electric field then will be larger and that ' s where the discharge will occur first. however, if you touch the doorknob and you get a spark, you feel a spark, and you look at the spark and you see that when you ' re 3 millimeters away from the doorknob that the spark develops, you can s - pretty sure that the potential difference between you and the door was of the order of 10000 volts, several thousand volts, at least. because over 3 millimeters it requires 10000 volts to get the 3 million volts per meter. when you comb your hair or when you take your shirt off you get little sparks, you can hear them and if it ' s dark you can see them, and you can be sure that at the sharp ends of this hair, of the fabric, that you have developed electric fields of the order of 3 million volts per meter. and then you get the automatic breakdown. now of course high voltage alone doesn ' t necessarily kill you. what - - what - - what matters is not so much the voltage to get killed but it ' s the current that goes through you. and current is charge per unit time. and so in si units it would be coulombs per second. for which we write a capital a which stands for ampere, the man who did a tremendous amount of research in this area, a frenchman. and so if you touch the doorknob the instantaneous current may actually be quite high. it may be an ampere even, but it may only last for 1 millisecond. and so that ' s not going to kill you. we all know that when you comb your hair that you don ' t die and you also know that when you take your shirt off even though you may hear the sparks that that ' s not lethal. so maybe in a future lecture we can discuss in some more details what it does take to actually execute someone electrically


' t die and you also know that when you take your shirt off even though you may hear the sparks that that ' s not lethal. so maybe in a future lecture we can discuss in some more details what it does take to actually execute someone electrically which is very unpleasant but nevertheless we would have to evaluate how long the current should last, how strong the current should be and then also during which parts of the body the current would cause lethal reactions. so i want to be a little bit more quantitative now uh and deepen our knowledge of the van de graaff. slowly we ' re going to understand how the van de graaff works. and today i want to calculate with you how much charge we can put on the van de graaff and what the maximum potential is at the surface. if we charge up the van de graaff, with charge q, then the potential of the surface is an equipotential, is q divided by 4 pi epsilon 0 r. and the electric field right here at the surface would be q divided by 4 pi epsilon 0 r squared. so in this case of spherical symmetry we have that the potential v equals e times r. but we know that e cannot exceed 3 million volts per meter. and so that gives you now a limit on the potential that we can give the van de graaff. so if you substitute in here 3 million volts per meter you can calculate what potential you can maximally reach for a given sphere with a given radius. and if we here have the radius and we here have the voltage, then if the radius of the sphere were 3 millimeters then you could not exceed a voltage of 10 kilovolts. if you did you would get this automatic electric breakdown. you would get a spark. if you have a sphere of 3 centimeters that would be 100 kilovolts and our van de graaff, which has a radius of 30 centimeters, would therefore be 1 million volts. and you could not exceed that. and in practice in fact this one doesn ' t even make it to 1 million volts. the sphere is not perfect. there are imperfections of the sphere. there are areas which have so - to - speak sharp points and so we won ' t make it to 1 million volts. we get a breakdown maybe at a few hundred thousand, maybe 300000 volts. you can now also calculate what the maximum charge is on the van de graaff. because if the maximum potential is 300000 vol


to 1 million volts. we get a breakdown maybe at a few hundred thousand, maybe 300000 volts. you can now also calculate what the maximum charge is on the van de graaff. because if the maximum potential is 300000 volts, you know the radius is. 3 meters, so you can calculate now what the maximum charge is that you can put on the van de graaff using that equation, will give you 10 microcoulombs. and so the maximum potential for our van de graaff is of the order of 300000 volts. so this gives you now a feeling, a quantitative feeling, for numbers, for what the - - can i put this down? so that gives you an idea of what our van de graaff can do, and later we will understand how the charge gets there. but at least you have some feeling now for potentials, and for the charges that are involved. if here ' s my van de graaff and i approach the van de graaff with a sphere which is connected to the earth and if this van de graaff had positive charge on it then the sphere will become negatively charged through induction and so you get field lines which go from the van de graaff to this object, always perpendicular to the equipotentials, so they go like this, and so the electric field here will probably be the strongest, and so the spark will then develop between this sphere and the van de graaff provided that you were close enough. so that you do achieve a electric field close to this sphere of about 3 million volts per meter. and i will show you that later, you will see more sparks today than you ' ve ever seen before in your life, but i want you to appreciate a little bit more about the sparks about lightning before uh i demonstrate that. so you get a little bit more out of it. if i approach the van de graaff not with the sphere but i would walk to the van de graaff being very courageous like this, i ' m also a pretty good conductor, i ' m also connected with the earth, then the chances are that the spark would develop first between my nose and the van de graaff, because that is the smallest curve, the sharpest curvature, the smallest radius, or certainly my head, would be a good candidate for being hit first. if i approach the van de graaff like this with my hand stretched, then chances are of course that


the smallest curve, the sharpest curvature, the smallest radius, or certainly my head, would be a good candidate for being hit first. if i approach the van de graaff like this with my hand stretched, then chances are of course that the sparks will first develop between my fingertips. because it ' s a very small radius and they ' re very close to the vandegraaff, and so that ' s where the discharge will occur. so before we will enjoy some of this, you will enjoy it, i will enjoy it less, um i want to talk a little bit about lightning with you first. because what you ' re going to see in a way is a form of lightning. there are 400000 thunderstorms every day on average on earth. there are about 100 lightning flashes every second. the top of a thundercloud becomes positive and the bottom becomes negative. the physics of that is not so easy, and probably incomplete, and i will not go into the details of the physics, but it does have to do with the flow of water drops. they become elongated, they can become charged because of friction, and they can break off, and they can transport charge. i will simply give you some facts. and so i will accept the fact that the cloud is going to be charged. this is the cloud. positive at the top, negative at the bottom. and here is the earth. because of induction, the earth of course will therefore become positively charged here, and so we ' re going to see field lines, electric field lines, which go from the earth to the cloud, always perpendicular to the equipotentials, something like this. i ' ll give you some dimensions, uh this may be something like 5 kilometers, this vertical distance d is about 1 kilometer. these are typical numbers, of course, it can vary enormously from thunderstorm to thunderstorm. and this height is something typically like 10 kilometers. and this allows us now to make some very interesting calculations to get some feeling for the potential difference between the cloud and the earth. that ' s the first thing we can do. if we make the simplifying assumption that the electric field is more or less constant here, it ' s like having two parallel plates, where the electric field is constant between them, then the potential difference delta v between the bottom of the cloud and the earth, is simply the electric field times the distance d. so this becomes e times d. but if the breakdown occurs at 3 million vol


the electric field is constant between them, then the potential difference delta v between the bottom of the cloud and the earth, is simply the electric field times the distance d. so this becomes e times d. but if the breakdown occurs at 3 million volts per meter - - by the way that ' s dry air, when it - - when there is a thunderstorm it ' s probably not so dry, but let ' s take the 3 million volts per meter, so we get 3 times 10 to the 6, that is for e, and the distance between the cloud and the earth let ' s take 1 kilometers. so that ' s 10 to the 3rd meters, so we get of the order of 3 billion volts between the earth and the clouds. and the values that are typically measured are several hundred million to 1 billion volts, so it is not all that different. you expect that the potential is probably less than what we have calculated because clearly uh these are not flat surfaces, there are trees, here on the ground, there are buildings on the ground, which are like sharp points, where the electric field will be locally higher, and so you will get a discharge at these sharp points first. and that means the potential difference between the cloud and the earth could then be less than the 3 billion that we have calculated here. it ' s only a back of the envelope calculation. the details of the physics of the discharge very complicated. but i want to share with you some facts without giving detailed explanations. the start of the lightning begins when electrons begin to flow from the cloud to the earth. they form a funnel, which is about 1 to 10 meters in diameter and we call that the step leader. the step leader moves about 100 miles per second and so it comes down in about 5 milliseconds. 5 milliseconds from here to here and it takes about half a coulomb to the earth. half a coulomb, for about 5 milliseconds, that means the current is about 100 amperes. the step leader creates a channel of ionized air, full of ions and full of electrons, which is an extremely good conductor. and with - - when this step leader reaches the ground there is this highly conductive channel and the electrons can now very quickly flow from this channel to the ground. and that starts first right here at the surface of the earth. that ' s where the electrons will first go to the earth. and then successively electrons which are higher up in the channel will


can now very quickly flow from this channel to the ground. and that starts first right here at the surface of the earth. that ' s where the electrons will first go to the earth. and then successively electrons which are higher up in the channel will make it down to the earth. and so you ' re going to see electrons going through the channel to the earth but first the electrons are closer to the earth than the electrons farther away and then even farther away. and this is actually where most of the action occurs. the current is now enormously high, 10000 to some 100000 amperes, and you heat the air, get a tremendous amount of light, the ions recombine and you get pressure, heat can produces pressure, and there comes your thunder. and so most of the action is not in the step leader but is in the second phenomenon, which we call the return stroke. which is from the earth to the cloud. and the speed of that return stroke is about 10 to 20 percent of the speed of light. during the return stroke there is about 5 coulombs exchange between the cloud and the earth, and 5 coulombs is a sizable fraction of the total charge that was on the cloud - - on the cloud the first place - - to start with. after a return stroke, maybe 20 milliseconds later, this whole process can start again. you can get a step leader. and you can get the return stroke. however, the step leader will now follow exactly the same path that was made before because that ' s where the air is ionized so that ' s where the conductivity is very high, so that ' s the easiest way to go. and this process can recur 5, 10, maybe 15 times. so what a - appears to you as one lightning bolt in fact could be 10 flashes back and forth between the cloud and the earth. and the - - the real light is not in the step leader, that ' s very little light, but the real light is in the return strokes. so 10 return strokes, which may be 20, 30, 40 milliseconds apart, appear to you and to me only as one flash, which would take place maybe in as little as a tenth of a second. and during these 5 or 10 return strokes you exchange between the cloud and the earth maybe a total of 25 to 50 coulombs, and that of course will lower the potential difference. and if the potential difference becomes too low then the process stops. you have


these 5 or 10 return strokes you exchange between the cloud and the earth maybe a total of 25 to 50 coulombs, and that of course will lower the potential difference. and if the potential difference becomes too low then the process stops. you have to wait now for the clouds to charge up again. and then lightning will strike again. and that can take anywhere from maybe 4, 5, 10, 20 seconds. and then you get another lightning bolt. the study of these - - of this process, of the step leader and of the return stroke, can be done with a camera, which is called the boys camera. let me first explain to you in detail - - in principle how it works. if this is the area on the film that is exposed by your lens suppose that i move the film at a very high speed to the left and suppose the step leader comes down and it sees some light from the step leader, then i may see on the film this. and from here to here would then be the 5 milliseconds which it takes the step leader to go from the cloud to the earth. now the return stroke takes place with way higher speed and so i see a tremendous amount of light because there ' s a lot of light in the return stroke. and of course this is very steep. because it goes 100 times faster up than the step leader came down. and so you can measure these times and so you can get the speed of the return stroke. and then later in time, maybe 30, 40 seconds later, on the film, you may see another return stroke. and you may see another one. and so you can see then how long the time was between the return strokes and you can also calculate their speeds. with a real camera it ' s not really the film that is moving but it is the - - the lens that is moving, and the way these pictures are taken, and i will show you one, is if this is photographic plate, then it is the camera that moves over the plate with a um very high speed, about 3000 revolutions per minute, and so you would get these - - this information then not horizontally but you get it spread out over the film. but you get the same information, you can calculate speeds and times. during the past decade, new forms of lightning have been discovered which occur way above the clouds. way higher up. red colors have been seen. red sprites they are called. and also blue jets. the light is very faint and it occurs only for a


past decade, new forms of lightning have been discovered which occur way above the clouds. way higher up. red colors have been seen. red sprites they are called. and also blue jets. the light is very faint and it occurs only for a very short amount of time. it ' s very difficult to photograph. i have not been able to get good slides for today. however, i did see some pictures on the web. and when you log into the web, when you visit the web 8. 02 which you should, then i give you directions how to access slides pictures of the red sprites and of the blue jets. the physics of that is not very well understood. it ' s being researched very heavily. but it ' s way above the clouds. there are also other forms of electric breakdown, of discharge. they are different in the sense that it ' s not an individual spark. but there is a continuous flow of - - of - - of charge. it occurs always from very sharp points. so there is a continuous current actually going on. and some of that you may have seen but you may not remember when we used a carbon arc here. we had two carbon arcs, two carbon rods, and we had a potential difference between them and we got a discharge between them which caused a tremendous amount of light, which we used for projection purposes. so a carbon arc discharge is such a form of discharge whereby you have a continuous current. it ' s not just sparks. if you take grass or trees or brushes for that matter, with thunderstorm activity, they can go into this discharge at their sharp tips. and we call this brush discharge, we call it st. elmo ' s fire, it ' s all the same thing, it ' s also called corona discharge. i normally call it corona discharge. it produces light because the ions when they neutralize produce light. heat makes sound, pressure, and so you can hear this cracking noise of the corona discharges. an airplane that flies or a car that drives, there is friction with the air, and any form of friction can charge things up. and so it ' s not uncommon at night that you can see this corona discharge from the tip of the wings of an airplane. i ' ve also seen it from cars. corona discharge from cars. which charge themselves up simply by driving through the air. the air flow would charge them up. you can hear it, cracking, and you can see it sometimes if it ' s dark enough, you see some


from cars. corona discharge from cars. which charge themselves up simply by driving through the air. the air flow would charge them up. you can hear it, cracking, and you can see it sometimes if it ' s dark enough, you see some light. in general it ' s bluish light. something completely on the side, going back to the lightning bolts, lightning bolts, the discharge, the moving electrons, can cause radio waves. and these radio waves you can receive on your car radio. and all of you have experienced this. driving around, lightning very far away, you can hear it on the radio. so that ' s telling you that there is lightning going on somewhere. after a thunderstorm, something that many of you may not have experienced because in the cities there is always - - always exhaust from cars, that spoils everything, but when you ' re out in the country after a thunderstorm there ' s a very special smell in the air. i love it. and that ' s ozone. o2, o2 in lightning becomes o3. and o3 has a wonderful smell, and you can really smell that. it ' s very typical. i hope that most of you sooner or later in life will have that experience. go to the country after a thunderstorm and you can really smell this ozone. let ' s now look at some slides. the first slide that you will see is one very classic slide made by gary ladd, at kitt peak observatory in arizona, uh what i like about this is that uh these are the observatories, the telescopes, in the domes, and of course when you ' re an astronomer, this is the kind of weather that you can do without. but nevertheless it happens. uh you see here return strokes, the light is definitely due to the return strokes, it ' s very bright. these are step l - leaders that never made it to the earth, and if a step leader doesn ' t make it to the earth you don ' t get a return stroke and so the light as you can see here is much less. and what you think here is only one bolt is probably at least 10, 5 to 10, maybe 15, flashes. all right next slide please. here you see the result of a boys camera exposure. for those of you who are sitting in front you can recognize maybe the empire state building here. and the empire state building is hit here by lightning at the very tip, that ' s the sharp edge, that ' s


of a boys camera exposure. for those of you who are sitting in front you can recognize maybe the empire state building here. and the empire state building is hit here by lightning at the very tip, that ' s the sharp edge, that ' s where you expect it to be hit. this is not taken when the camera was rotating. this is just the exposure the way you and i would see it. not moving camera but here you see the result of the rotating boys camera. and this is the same flash. so here you see the return stroke, the - - the light from the step leader is too faint. you can ' t see that. so here is the return stroke and then this time separation may be 30 or 40 milliseconds, see another stroke, you see another one, and another one, so there ' s 6 here, looks like you see a double one here. and so you have 6 or 7 of these return strokes. and this is the way that you can study speeds and how much charge actually is exchanged between these uh between the clouds and in this case the empire state building. uh the next slide shows you a corona discharge in the laboratory this is a high voltage supply with a very sharp tip - - tip here at the end, the sharp point, and here you see not individual sparks, you don ' t call this lightning but this is what you would call the st. elmo ' s fire, the corona discharge is bluish light. and in fact when you are close to this power supply you can also smell the ozone. it also produces locally ozone. and you can see it. if you make it dark in the laboratory you can see some bluish light. uh when i was a graduate student i had to build power supplies, high voltage power supplies, and i remember when my soldering job was not a very good job that means when i take the solder ironing off then i could draw a little sharp point, the solder, and that would then later cause me problems with corona discharge, that means i would have to redo the soldering so that the radius of the solder joint would become larger, so no sharp points. that ' s enough for the slides right now. benjamin franklin invented the lightning rod. his idea was that through the lightning rod you would get a continuous discharge, corona discharge, between the cloud and the building. and therefore you would keep the potential difference low. and so there would be no danger of lightning. and so he advised king george


idea was that through the lightning rod you would get a continuous discharge, corona discharge, between the cloud and the building. and therefore you would keep the potential difference low. and so there would be no danger of lightning. and so he advised king george the third to put these sharp points on the royal palace and on uh powder houses, ammunition, storage places for ammunition. there was a lot of opposition against franklin. uh they argued that uh a lightning rod will only attract lightning. and that the effect of the discharge, lowering the potential difference, would be insignificant. but nevertheless the king followed franklin ' s advice and after the sharp rods, the lightning rods, were placed, there was a lightning bolt that hit one of the ammunition places at pearl fleet, but there was very little damage. and so we now know that on the one hand the discharge is indeed insignificant. and so the opposition was correct. and in fact you do attract lightning, unlike what franklin had hoped for. however, if your lightning rod is thick enough that it can handle the high current, which is 10000 or 100000 amperes, then the current will go through the lightning rod and therefore there will not be an explosion. so it will not hit the building. so it will be confined to the lightning rod. and so it worked but for different reasons than franklin had in mind, but he had the right intuition. was a very great scientist, and great statesman. and so his lightning rod survived up to today. so now i want to return to the van de graaff and show you some of the things that we have discussed. and the first thing that i would want to do is create some sparks. i run the van de graaff and i will approach it with this small sphere, small radius, and as i come closer and closer, the electric field will build up here and then i would predict that if sparks fly over, that they would go between the van de graaff and this uh this sphere. this sphere is grounded. and so any current that will flow will flow not through walter lewin but will go through the ground, so there ' s no danger that anything will happen to me. at least not yet. you already hear some cracking noise. that means there are already sparks flying around inside there. it ' s very hard to avoid, there are always some sharp edges in there that we cannot remove. this is not an ideal instrument. but i still think i will be able to show you some lightning. by coming closer.


around inside there. it ' s very hard to avoid, there are always some sharp edges in there that we cannot remove. this is not an ideal instrument. but i still think i will be able to show you some lightning. by coming closer. there we go. so what you think is only one spark may well be several like these return strokes, the way i described with lightning. so what you ' re seeing here now is that the electric field locally has become larger than 3 million volts per meter and then you ' re going to this discharge phenomenon that we described, and that gives you then - - that gives you the lightning. what i will do now is i would like you to experience - - although it may not be so fascinating for you - - to experience a corona discharge between a very sharp point that i have here, extremely sharp, and the van de graaff. and the only way that i can convince you that there is indeed going to be a discharge between this point and the van de graaff is by approaching the van de graaff and this cracking noise that you hear now will disappear. and the reason why it will disappear is that if i get a corona discharge between the tip and the van de graaff it will drain current, it will lower the potential and so that cracking noise will disappear. so the sparks which are now flying over will not fly over anymore. you will not be able to see the light. it ' s - - there ' s too much light here. although i can probably see at the tip here this blue light. so i ' m going to approach the van de graaff now. it ' s almost as if i had a lightning rod and i ' m not worried at all because if any current starts flowing it goes through this rod, which is like a lightning rod to the earth. so i ' m not worried at all. i just am very brave, very courageous, approaching the v - the van de graaff, and i want you to listen to that cracking noise. that cracking noise will disappear when i ' m going to be - - draw a current through this sharp point. oh, boy, there i go. and the cracking stops. and i can actually see here some glowing discharge, bluish. will be impossible for you to see. i can come closer, i ' m not worried. and so i ' m draining charge now off the van de graaff thereby lowering the potential of the van de graaff and so


bluish. will be impossible for you to see. i can come closer, i ' m not worried. and so i ' m draining charge now off the van de graaff thereby lowering the potential of the van de graaff and so these crazy sparks that occur here can no longer occur. but now they will. can you hear them? and now you can ' t. if i were crazy then i would develop a corona discharge between the van de graaff and myself. one way i could do that is by approach it with my fingertips as i mentioned earlier, but that may be a little bit too dangerous because i may draw a spark, i may be hit by lightning, which is the last thing that i would want today. however, a corona discharge using these tinsels may be less dangerous. so i get a continuous flow of current which now unfortunately doesn ' t go through the lightning rod but now it goes straight through my body. and i can assure you that i can feel that. it ' s probably a very low current. it may be only a few microamperes. but it ' s not funny. it ' s not pleasant. but anything for my students, what the hell. there we go. ya ya ya ya ya. you see tinsels, i ' m now in a corona discharge and i feel the current through my fingers, it ' s a continuous discharge now. this is st. you can ' t h - ah, there was lightning. boy, you got something for your 27000 dollars. so you saw both corona discharge and you saw lightning. boy, you were luckier than the - - than the first class by the way. clearly lightning can be dangerous, lightning can cause a fire, it can excite, it can explode fumes, if you gas your car just the flow of gasoline can charge up the nozzle, friction can charge things up, that ' s why the nozzle is always grounded, because a spark could cause a major explosion. if you fill a balloon with hydrogen then the flow of hydrogen is friction, can charge up the balloon and a spark can then ignite the hydrogen. and this has led to a classic tragic accident, it ' s a long time ago. but it ' s so classic that i really have to show this to you. hitler was very proud of his large airships. they ' re named after graf zeppelin the germans called them the zeppelins, we call them dirigibles or blimps. and


this post has been first published on access - info : open government data and is actually circulating various e - mailing lists. i think it is a really important initiative and worth reblogging it. open government data project : research project by access info and the open knowledge foundation, in collaboration with the open society information program, to map out and evaluate the current state of initiatives to promote access to government data in formats that can be freely used, reused, and distributed by anyone. the project will also identify the obstacles to accessing and reusing public data and recommendations for future initiatives to address these. on this page you can read more about the issue and find out how you can get involved in the project. what is open government data? the release of databases and other collections of information by government departments in formats that can be freely used, reused and distributed. release is generally proactive, without the need for access to information requests. - an example : in 2007, the uk government released a database with locations of bicycle accidents around the country. this information was linked by members of the public to maps, making it possible for cyclists to plan safer journeys avoiding the black spots. - another example : in australia, in january 2010, government released the national public toilet map which shows the location of more than 14, 000 public and private public toilet facilities with data such as opening hours, availability of baby changing rooms, and accessibility for people with disabilities. sounds funny? think of the possibilities : associations of disabled persons can provide a database for their members to plan journeys ; mothers could access a service by mobile phone to locate the nearest baby changing room. read more in a good article from the economist ( 4 february 2010 ) data and transparency : of governments and geeks what are governments doing to promote this? there are currently a number of exciting initiatives to release government data in bulk, these include : - united states : on 21 may 2009 the us government launched data. gov whose purpose is to give direct public access to machine - readable datasets generated by the executive branch of the us federal government. an initial 47 datasets are on line, of the thousands planned for release. - united kingdom : working with tim berners - lee, one of the inventors of the world wide web, the uk government has created data. gov. uk, a single online access point for government data, launched on 21 january 2010. - australia : the data. australia. gov. au website encourages users to “ make government information even more useful by mashing -


released in formats that can ’ t be read by computers is difficult to reuse. information is held in proprietary formats which users have to buy. data is subject to copyright or released under restrictive licences. these are issues which are being researched under this project and will be the subject of recommendations for future campaigns by activists from the access to information and open government data communities what does this mean for the access to information community? for full enjoyment of the right of access to information and the related right to freedom of expression, people need to have access to government data in formats which can be used by anyone – so preferably in open source formats – and free from copyright, licences, and other restrictions on reuse. if government data is provided to the public in formats which mean that it cannot easily be reused, processed, or have value added, then the right to information is seriously undermined. it sounds rather technical! sometimes it is. as the economist article says, this is “ a geek ’ s dream : plenty for creative types to work on, but a bit baffling to the lay person. ” this project aims to demystify open government data issues and break through the jargon, so that they can be understood by access to information activists and other human rights campaigners. what will be done under this project? access info and the open knowledge foundation will identify and analyse the main initiatives related to open government data. we will analyse what this means for the right of access to information and for other developing fields such as e - government ( electronic access to public services ) and e - democracy ( electronic participation in government decision - making and electronic voting ). based on the research and analysis we will develop recommendations for future activities which could be carried out by the open government data, access to information, and e - government communities together. how do i get involved? go to the open government data project website and tell us about your campaigns or government initiatives in your country. the deadline for sending us information is 15 march 2010. we will then be producing a mapping report with info on the next phase of the campaign. there will be an international meeting to launch the report and discuss next steps in london on 22 april 2010. write to the project coordinators to tell us about your projects and to join the project : - helen darbishire, access info, helen [ at > access - info. org - jonathan gray, open knowledge foundation, at jonathan. gray < at ] okfn. org why is open government data important? 1


on november 25, 1952, three months after returning from england, pauling finally made a serious stab at a structure for dna. the immediate spur was a caltech biology seminar given by robley williams, a berkeley professor who had done some amazing work with an electron microscope. through a complicated technique he was able to get images of incredibly small biological structures. pauling was spellbound. one of williams ' s photos showed long, tangled strands of sodium ribonucleate, the salt of a form of nucleic acid, shaded so that three - dimensional details could be seen. to pauling the strands appeared cylindrical. he guessed then, looking at these black - and - white slides in the darkened seminar room, that dna was likely to be a helix. no other conformation would fit both astbury ' s x - ray patterns of the molecule and the photos he was seeing. even better, williams was able to estimate the sizes of structures on his photos, and his work showed that each strand was about 15 angstroms across. pauling was interested enough to ask him to repeat the figure, which williams qualified by noting the difficulty he had in making precise measurements. the next day, pauling sat at his desk with a pencil, a sheaf of paper, and a slide rule. new data that summer from alexander todd ' s laboratory had confirmed the linkage points between the sugars and phosphates in dna ; other work showed where they connected to the bases. pauling was already convinced from his earlier work that the various - sized bases had to be on the outside of the molecule ; the phosphates, on the inside. now he knew that the molecule was probably helical. these were his starting points for a preliminary look at dna. he still lacked critical data - he had no decent x - ray images, for instance, and no firm structural data on the precise sizes and bonding angles of the base - sugar - phosphate building blocks of dna - but he went with what he had. it was a mistake. after a few pages of theorizing, using sketchy and sometimes incorrect data, pauling became convinced - as watson and crick had been at first - that dna was a three - stranded structure with the phosphates on the inside. unfortunately, he had no rosalind franklin to set him right.


physical environment is subject to continuous modification from natural causes, such as tectonic forces, temperature extremes, fire, wind and river erosion, vegetation processes, and animal action. no less than natural agents, human actions can result in widespread and irreversible environmental change. many of these processes occur insidiously over prolonged periods. in such instances, the effects often are cumulative. other human actions may be more sudden and concentrated, resulting in immediate and noticeable change. whether continuous or precipitous, these human actions frequently have degraded the affected environment. the nineteenth century, a time of british consolidation in gangetic india, witnessed both types of phenomena. traditional environmental alterations continued, while imported technologies introduced new, more threatening agents of change. agents of continuous change the banaras region, like most of the gangetic plain, has been continuously populated for some twenty - five hundred years. in the process local residents established an important urban center, maintained its streets and buildings, connected it to other communities, supplied its industrial needs, and fed its population. throughout this time human occupation affected the surroundings in a variety of ways. land use and resource depletion. over the centuries while banaras city grew, its inhabitants exploited the adjoining terrain and its resources. they cultivated the land to near capacity ; hunted wildlife ; raised livestock ; and extracted timber, fuel, stone, sand, clay, and groundwater. those materials and supplies which were unavailable locally were imported and brought in by road or stream. as banaras continued to grow and prosper, surrounding lands strained to supply the rising needs of the city and its visitors. by 1800 the region ' s resource base was becoming strained. the town itself was built on the site of the legendary forest of bliss. but by the nineteenth century, according to diana eck, townspeople retained only memories of the once luxuriant woods. one central neighborhood came to be known as the " cut - down forest " ( eck 1982 : 29 ). in the countryside, too, large tracts had been cleared for farming, leaving only isolated trees and planted groves. the extensive fields in place by 1800 blanketed what was once a natural habitat of dense forest. the original cover included stands of valuable trees, such as sal ( shorea robusta ) shisham ( dalbergia sissoo ), jaman ( eugenia jambolana ), mahua ( bassia latifolia ), ber ( ziziphus jujuba ), pipal ( ficus religiosa


the bereghinya planitia quadrangle ( v - 8 ) of venus is bounded by 25º and 50º n. latitude, 0º and 30º e. longitude. it is one of 62 quadrangles covering the entire planet at a scale of 1 : 5, 000, 000. the quadrangle derives its name from the plains region bereghinya planitia, most of which falls within the boundaries of the quadrangle. bereghinya are benevolent protective female spirits in east slavic mythology. these spirits were considered as guardians of the home, and traditional homes commonly had carvings of bereghinya around their windows. in addition, these spirits were associated with riverbanks, so some of them were envisioned as being women with fish tails, similar to mermaids. the bereghinya planitia quadrangle comprises mostly plains materials that have been highly modified by younger structures, mostly related to coronae. the map area contains all or part of 22 named coronae, 4 named deformation belts, and 2 major lava channel systems having extensive associated volcanic flows. in addition, other valles, a deformation belt, and coronae occur within the quadrangle but are unnamed. the quadrangle hosts 24 impact craters and 6 bright splotches believed due to explosive destruction of bolides in the atmosphere. many of the impact craters have associated dark halos or parabolas, and four are accompanied by fields of secondary craters. also present is a complex array of faults, fractures, and wrinkle ridges. the quadrangle is geologically the quadrangle is geologically interesting primarily because of the large population of coronae, many of which are connected to each other by belts of closely spaced, complex wrinkle ridges producing a spiderlike pattern in which the " bodies " are coronae and the " legs " are the connecting belts. these coronae were named " arachnoids " by members of the soviet venera team. the problems of more than local interest include the kinematics and dynamics of the arachnoids, the structural and volcanic evolution of the coronae, and the age of the widespread background plains relative to structures and other material units. download this map as a pdf document ( 44 x 35 inches ; 28. 4 mb ) download the accompanying pamphlet as a 19 - page pdf document ( 304 kb ) | help | pdf help | geopubs main page | other planetary maps | | privacy statement | disclaimer | accessibility | | geologic division | astrogeology research program | this


- manual testing - test management - test automation - test templates - testing resources types of testing - page 3 contd.. adhoc testing is a commonly used term for software testing performed without planning and documentation. the tests are intended to be run only once, unless a defect is discovered. exploratory testing is a method of manual testing that is described as simultaneous learning, design and execution. testing which covers all combination ' s of input values and preconditions for an element of the software under test. a sanity test is a narrow regression test that focuses on one or a few areas of functionality. sanity testing is usually narrow and deep. testing few functions / parameters and checking all their main features. in which one can perform testing on an overall application ( all features ) initially to check whether the application is proper in terms of availability and usability. sanity testing is done by test engineer. in software industry, smoke testing is a wide and shallow approach whereby all areas of the application are tested, without getting into too deep. smoke testing originated in the hardware testing practice of turning on a new piece of hardware for the first time and considering it a success if it does not catch fire and smoke. when a build is received, a smoke test is run to ascertain if the build is stable and it can be considered for further testing. smoke testing is done by developer or white box engineers. soak testing involves testing a system with a significant load extended over a significant period of time, to discover how the system behaves under sustained use. for example, in software testing, a system may behave exactly as expected when tested for 1 hour. however, when it is tested for 3 hours, problems such as memory leaks cause the system to fail or behave randomly.


seen at the air force space and missile museum at cape canaveral air force station, florida — it ’ s a model of the dinosaur dynasoar space plane : likely the most poorly - named program ever conceived, the dynasoar ( for dynamic soaring ) was an early attempt at making a reusable manned space plane — essentially a mini - shuttle, and in some sense a follow - on to the x - 15 experimental aircraft. first proposed in 1957, the u. s. air force saw this single - seat craft as their way into space — and assigned it a dizzying future array of tasks. variants were discussed for reconnaissance, long - range weapons delivery, and even in - orbit warfare ( the soviets were planning similar vehicles at the time, so this was hardly unilateral thinking ). ultimately, the program wound down in 1963, victim of an unclear mission, escalating costs, and a hostile political environment — just months away from completion of the first flight - worthy vehicle. in its early days, dynasoar was hobbled by the eisenhower administration ’ s desire to avoid military competition with nasa ’ s mission of manned orbital flight. once the kennedy administration was in place, defense secretary mcnamara ultimately cancelled dynasoar in favor of military use of the gemini spacecraft that nasa was then developing ( although it too would soon be cancelled ).


let us now turn our attention to the theological teachings of the jahmiyya, [ who trace their name and origin to jahm ibn safwan abu muhriz ]. peculiar to jahm ibn safwan is the assertion that, although certain effects may appear to be produced by human causation, it is only in a metaphorical sense [ ' ala ' l - majaz ] that the origin of such effects can be attributed to the human being, not as a matter of reality [ la ' ala ' l - haqiqa ]. [ in other words, to attribute any action to a human being is merely a figure of speech ], just as it is when one says : " the date palm grew tall, and the fruit ripened. " he always refused to profess the doctrine that allah is cognizant of things prior to their coming into existence [ ' alim bi ' l - ashya ' i qabla kawniha ]. he maintained that the garden of paradise and the fire of hell will eventually cease to exist. he also denied the reality of the [ divine ] attributes [ sifat ]. the theological school [ madhhab ] founded by jahm was located in a town called tirmidh, or, according to some authorities, in marw. he is the author of a literary work on the negation of the [ divine ] attributes. he was put to death by muslim ibn ahwad al - marwani.


note : the following is a brief six - page excerpt from a 60 page chapter on the origins of the american empire at the end of world war ii. the chapter, nearly complete, is one of several chapters in a book being funded and facilitated through the people ’ s book project, which is aimed at producing a multi - volume book on a modern history of institutions and ideas of power and resistance. included within the volumes are : the emergence of nation - states, capitalism, and central banking ; the rise of the european empires and colonization ; the emergence of new dynastic powers, namely the banking and industrial families of the rothschilds, rockefellers, morgans, et. al. ; the development of the mass education system as a means of social control ; the emergence and evolution of university education, the social sciences, and the formation of new concepts of social control and methods of social engineering ; the development, purpose, and effects of philanthropic foundations on society ; the emergence and evolution of the consumer culture, advertising, public relations, and advanced systems of propaganda ; the development of the ‘ modern institutional society ’, with an examination of the different brands in communist, fascist, and liberal democratic states ; the development and intent of the welfare state, social services, and management of the poor ; the effect of two world wars, and the formation of the american empire with its political, military, intelligence, economic, financial, and cultural apparatus and institutions of expansion, including the american foundations, think tanks, world bank, imf, un, nato, cia, pentagon, etc. ; the role of international think tanks like the bilderberg group and the trilateral commission in shaping and re - shaping world order and expanding dominance and control of the world ; the formation of an apparatus of global governance and the ideology of globalism ; population control and the environmental movement ; and finally the emergence, evolution, and role of science, technology, psychology, and psychiatry on the development of a global scientific dictatorship … and what we can do to change all of this! the above is not even an exhaustive list of the scope of this multi - volume book. over 500 pages has been written thus far, and there is a great deal more to go, at which point the end result will be broken up into relevant sections as a complete volume on the modern history of ideas and institutions of power in our world, asking and answering the questions : what is the nature of our global society? how did we get here? who brought us here? when did this begin? where


and other favors, ” yet, contends schlesinger, “ these are marginal to the subject of direct control, ” and instead, “ far from ruling an empire in the old sense, ” america “ has become the virtual prisoner of its client states. ” some other commentators referred to america as a “ virtual ” or even “ inadvertent ” imperial power. the notion of america as a “ reluctant imperialist ” or a “ benevolent empire ” is not a new one. this has been the mainstay within the academic literature and policy - planning circles to both advocate for and justify the existence of american domination of the world. the concept of the reluctant, yet benevolent great power presents an image of a dutiful personage coming to the aid of those in need, following the responsibility which is derived from great power ; that america ’ s rise to economic prominence – also seen as the product of free and democratic initiative and ideals ( thus negating america ’ s long history of being a slave state and subsequently a brutal industrial society ) – was the precursor to america being thrown the title of ‘ global power, ’ and with that title bestowed upon it – like a child - king still unsure of his own abilities to rule – took up the activities of a global power with a desire to bring the rest of the world the same altruistic truths and enlightened ideals which made america flourish so ; that america ’ s gift to the world was to spread freedom and democracy, in the economic, political, and social spheres. this myth has been a constant foundation for the advocacy and justification of empire. its importance rests most especially on the ideals and global public opinion which prevailed as the great european empires waned and ultimately collapsed through two world wars. the colonized peoples of the world had had enough of empire, had suffered so immeasurably and consistently under its tutelage, that the concept of empire was so discredited in the eyes of the world ’ s majority as to be incapable of justifying in the formal imperial - colonial sense. at home, america ’ s domestic political situation and public opinion had been largely isolationist, seeking to refrain from an expansive foreign policy, leading many american presidents and strategists to bemoan the struggle for empire beyond the continent on the reluctance of the american people and congress to pursue aggressive expansionism ( save for the expansion across the continent, wiping out native american populations for american lebensraum and the slow, increasing expression of trans - sovereign rights in latin america


lebensraum ) throughout the western hemisphere and beyond, as well as trade and “ economic integration ” with the far east and the british empire / commonwealth blocs. the report stated bluntly, “ as a minimum, the american ‘ national interests ’ involved the free access to markets and raw materials in the british empire, the far east, and the entire western hemisphere. ” this was the foundation for the grand area designs of the council in the post - war world. the grand area project emphasized that for america to manage the “ grand areas ” of the world, multilateral organizations would be needed to help facilitate “ appropriate measures in the fields of trade, investment, and monetary arrangements. ” the study further emphasized the need to maintain “ military supremacy ” in order to help facilitate control of these areas. as the council ’ s 1940 report to the u. s. state department stated : “ the foremost requirement of the united states in a world in which it proposes to hold unquestioned power is the rapid fulfillment of a program of complete re - armament, ” which would “ involve increased military expenditures and other risks. ” while the grand area project was made and designed for the united states during world war ii, it included plans for the post - war world, and included continental europe in its designs following the assumed defeat of germany. thus, as economist ismael hossein - zadeh wrote, “ making the grand area global. ” the idea behind the “ grand area ” was “ even more grandiose – one world economy dominated by the united states, ” and the study itself suggested that the grand area “ would then be an organized nucleus for building an integrated world economy after the war. ” as shoup and minter wrote in their study of the council, imperial brain trust, “ the united states had to enter the war and organize a new world order satisfactory to the united states. ” benevolent, indeed. following pearl harbor and the u. s. entry into the war, the council concluded as early as 1941 that the defeat of the axis powers was simply a matter of time. as such, they were advancing their plans for the post - war world, expanding the grand area to : include the entire globe. a new world order with international political and economic institutions was projected, which would join and integrate all of the earth ’ s nations under the leadership of the united states. the unification of the whole world was now the aim of the council [ on foreign relations ] and government planners. as a part of this planning process,


which would join and integrate all of the earth ’ s nations under the leadership of the united states. the unification of the whole world was now the aim of the council [ on foreign relations ] and government planners. as a part of this planning process, the u. s. department of state formed the advisory committee on postwar foreign policy in late december of 1941, of which the first document that was produced, “ stressed the danger of another world depression and the need to provide confidence in world economic stability. ” thus, “ the united states had to be involved with the internal affairs of the key industrial and raw materials - producing countries. ” a key question in this was, as one postwar planner articulated, “ how to create purchasing power outside of our country which would be converted into domestic purchasing power through exportation. ” the idea was about “ devising appropriate institutions ” which would fulfill this role, ultimately resting with the formation of the imf and the international bank for reconstruction and development ( later known as the world bank ). the postwar planners had to continually construct an idea of an international order, directed by the united states, which would not so easily resemble the formal colonial period or its methods of exerting hegemony. recommendations of the council suggested that such new international financial institutions were necessary in terms of “ stabilizing currencies and facilitating programs of capital investment for constructive undertakings in backward and underdeveloped regions. ” these plans included for the establishment of an international reconstruction finance corporations and an “ international investment agency which would stimulate world trade and prosperity by facilitating investment in development programs the world over. ” these plans were drafted in recommendations and given to president roosevelt and the department of state. one council member suggested that, “ it might be wise to set up two financial institutions : one an international exchange stabilization board and one an international bank to handle short - term transactions not directly concerned with stabilization. ” thus, the council drafted in 1941 and 1942 plans that would result in the formation of the world bank and the international monetary fund ( imf ), which formally emerged from the 1944 bretton woods conference, an event that is commonly acknowledged as the “ birthplace ” of the world bank and imf, thus ignoring their ideological origins at the council on foreign relations two - to - three years prior. the internal department committees established in the department of state and treasury were well represented by council members who drew up the final plans for the creation of these two major institutions. whereas the league of nations had been a major objective of the rockefeller foundation and carnegie


, no. 2, spring 1999 ), page 356. ibid, pages 358 - 359. cfr, war and peace. cfr history : http : / / www. cfr. org / about / history / cfr / war _ peace. html joan roelofs, foundations and public policy : the mask of pluralism ( new york : state university of new york press, 2003 ), page 74. ismael hossein - zadeh, the political economy of u. s. militarism ( new york : palgrave macmillan, 2006 ), pages 43 - 45. ibid, page 45. ibid, page 46. laurence h. shoup and william minter, imperial brain trust : the council on foreign relations and united states foreign policy ( authors choice press, new york : 2004 ), page 118. ismael hossein - zadeh, the political economy of u. s. militarism ( new york : palgrave macmillan, 2006 ), page 48. ibid, pages 49 - 51. laurence h. shoup and william minter, imperial brain trust : the council on foreign relations and united states foreign policy ( authors choice press, new york : 2004 ), pages 166 - 167. ibid, pages 168 - 169. joan roelofs, foundations and public policy : the mask of pluralism ( new york : state university of new york press, 2003 ), page 159. ismael hossein - zadeh, the political economy of u. s. militarism ( new york : palgrave macmillan, 2006 ), page 51. laurence h. shoup and william minter, imperial brain trust : the council on foreign relations and united states foreign policy ( authors choice press, new york : 2004 ), pages 169 - 171. joan roelofs, foundations and public policy : the mask of pluralism ( new york : state university of new york press, 2003 ), page 160.


those of us with even a passing interest in science are used to the idea that computers play a central role in understanding physics and chemistry, especially high - powered computation used in areas such as weather prediction and molecular visualization. however, over the past few years, a new target for that computation has emerged and begun to attract media attention. it ' s called computational biology ( or more catchy, bioinformatics ) and it refers to the digital storage, categorization, and analysis of biological data. if your most recent encounter with biology took place in high school, you may be surprised by any such crossover with computing. although i always found it fascinating, i remember biology never quite having the rigor of its counterparts in the science curriculum. some cells did this, other cells had that, and different organisms did all sorts of strange things, especially when dissected by over - enthusiastic schoolchildren. but there seemed to be few universal principles equivalent in scope to newton ' s equations or the periodic table of elements. digitizing life - - thanks to the wonders of molecular biology, many such fundamentals are now known to exist. an overview of some of the basics should give an impression of what is involved - bear in mind that we ' re dealing with the natural world in all its complexity, so everything that follows has been vastly simplified. life as we know it is encoded in a set of long molecules called dna, identical copies of which are found in every cell in a living organism such as a human being. everything that happens within an organism can be traced back to its dna - just like the hard disk in a computer. in humans, each cell contains 46 separate dna molecules called chromosomes, analogous perhaps to hard disk partitions. your chromosomes contain a mixture of information duplicated from those of your parents, which is one reason why you inherited so many of their characteristics. any one dna molecule consists of a series of connected nucleotides forming a chain that can run to lengths of many millions. there are only four possible nucleotides, so any dna molecule can be represented as a sequence using only four letters. this is where the digitization begins - the entire set of chromosomes for a human being can be stored in a few gigabytes of space ( even less after compression ) and you can even download a recent draft to your own computer. according to present - day understanding, only a fraction of your dna has a purpose - the other 98 percent or so is affectionately named " junk. " the meaningful bits, known as


) and you can even download a recent draft to your own computer. according to present - day understanding, only a fraction of your dna has a purpose - the other 98 percent or so is affectionately named " junk. " the meaningful bits, known as genes, are short stretches scattered unevenly throughout the chromosomes ( think of them as fragmented program files, if you like ). they can be pretty hard to find - we currently have confirmed the existence of about 15, 000 human genes, but scientists are still bickering over the total number - most estimates lie around 30, 000. there ' s even a sweepstakes where you can add your own guess. genes are interesting because machinery in the cell translates them into another type of molecule called proteins. these proteins perform the organism ' s real metabolic work and can be thought of as currently running programs. a protein molecule contains a series of connected amino acids forming a chain, similar to how nucleotides make up dna. however, in contrast to dna, proteins are made from 20 different amino acids and are rarely more than a few thousand such elements in length. sequences of proteins are another type of digital data that bioinformatics regularly deals with. how are these proteins able to do all the work set out for them : building cells, transporting materials, sending signals and carefully managing each cell ' s energy factory? when released into a cell ' s watery innards, proteins fold up upon themselves, forming a huge variety of shapes that make them connect to other proteins and molecules in specific ways, catalyzing any number of chemical reactions. trying to work out which shape a particular protein sequence will fold into is an extremely difficult problem. a biannual contest called casp ( a shortened acronym for critical assessment of techniques for protein structure prediction ) is held between different research groups around the world, and ibm is building its fastest ever supercomputer to work on it, at a hoped - for rate of no more than one protein per year. again, this is just a basic overview. if you ' re thirsting for more information on molecular genetics, the u. s. human genome project has published a good online primer. open - sourcing the human being - - with the basic biology lesson out of the way, let ' s talk about how bioinformatics applies to the real world. one bioinformatics application you ' ve probably heard of is the human genome project. its seemingly simple goal is to read the roughly three billion nucleotides that make up the


talk about how bioinformatics applies to the real world. one bioinformatics application you ' ve probably heard of is the human genome project. its seemingly simple goal is to read the roughly three billion nucleotides that make up the human set of chromosomes. this is made possible by the fact that, even though there are millions of points at which healthy human dna sequences can differ from one another, every one of us is identical in the other 99. 9 percent of points. if you find that scary ( or perhaps inspiring ), remember that your dna is also about 99 percent identical to the chimp at your local zoo. discussions on the genome project began in 1984, but it was not until 1995 that the work began in earnest via an international collaboration of publicly funded laboratories in the united states, united kingdom, france, japan, germany, and china. the public project moved along slowly until 1999 when celera genomics, a private venture, joined the fray. armed with an improved experimental method and gobs of computing power, celera promised to complete a first draft of the genome within a year. after much politicized mud slinging, a deal was made and the two groups ' results were published simultaneously in february 2001. what does all this have to do with bioinformatics? for a start, computers were required to store and index the resulting sequences and make them available to researchers around the world over the internet. but the real algorithmic problem stemmed from the way in which dna molecules have to be read. in the biological world, there is no such thing as a debugger which lets you freeze a cell and poke around inside, observing and manipulating at will. instead, a series of steps must be cleverly combined for a scientist to gain access to a desired item of information. for any dna molecule, only about the first 1, 000 nucleotides can be ascertained using available laboratory techniques. longer sequences are scanned by making several copies of the molecule and breaking these up randomly into short fragments, each of which is read separately. the original order of these fragments is lost, so, after reading them, there remains the task of reconstructing the original sequence. it ' s not unlike trying to rebuild an encyclopedia using a few photocopies which have been run through an office shredder - the number of possibilities to be tried is vast. forget about trying to do it by hand - celera ' s draft build required about a week of running time on a 56 -


bioinformatics applications run over the internet. unix ' s stable and efficient implementation of tcp / ip, in conjunction with the free apache web server, make it ideal for providing these web - based services. for some idea of what ' s available, take a look at the site of the american national center for biotechnology information. it should be fairly obvious where this takes us : mac os x, soon to be the mainstream macintosh operating system, is not only based on unix but provides full support for all of its tools - perl, grep, and apache included. on its own, this does not necessarily place it ahead of other unix platforms. but if we add the fact that it contains a modern user interface and runs desktop applications such as microsoft office and modern web browsers, it ' s not hard to see why mac os x is a natural choice for bioinformatics servers and desktops. this has been noted in several places, including an o ' reilly network article and an apple viewpoint article. it ' s also proven to be more than wishful thinking : genentech, the company that ordered 1, 000 new imacs ( and whose chairman and ceo is one of apple ' s board members ), is one of the founders of the biotechnology industry. a further bonus for macs is that the powerpc g4 processor, with its velocity engine processing unit, is ideal for many types of biological computations. blast ( short for basic local alignment search tool ) is probably the most popular bioinformatics tool available today. it takes the sequence of a dna or protein molecule as input and searches for other known molecules which are likely to be connected in evolutionary origin or biological function. apple ' s advanced computation group, in collaboration with others, developed a high - throughput version of blast, which they claim makes a dual 1 ghz power mac g4 up to five times faster than a pc with a 2 ghz pentium 4 processor. fast blast searches are crucial to today ' s biologists. try this at home - - there is at least one way in which all mac users can get involved in computational biology. a project named folding @ home, developed in the same style as u. c. berkeley ' s alien - searching seti @ home, lets you contribute to a distributed effort to calculate the physical structure of protein sequences. folding @ home ' s mac os x client, a screensaver and application, is now available and provides a real - time graphical view of the structures being tested. that aside,