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Sunday, April 29, 2007
Guest Post: Bill Zajc
To put those remarks in some context, I was a child of the late 1950's and 1960's. Optimism about science and technology was everywhere (or so it seemed to me), and you couldn't help (or so it seemed to me) to be fascinated with space exploration, nuclear power, 'electronic brains', and so on. It's hard to convey that zeitgeist today. Some sense of it comes through in Homer Hickam's wonderfully evocative Rocket Boys; another avenue is simply to peruse the advertisements in the magazines of the era. It's hard to beat the effect of being led out into your backyard by your father to stare out a satellite tracing its path across the night sky (I am guessing it was an Echo satellite as we could see it without binoculars or telescope.)
In retrospect, I suppose our household would have been classified 'lower' middle-class as well as 'non-intellectual': my father was an auto mechanic, my mother a homemaker and nurse; both worked damn hard to make ends meet, so for this and other reasons no music lessons, foreign languages, philosophical discussions, or great books. But there were books everywhere in the house, more than enough to stimulate my lifelong love of reading and learning. I recall the excitement each week when my mother brought home a new volume of The Golden Book Encyclopedia, which was being sold as some sort of promotion through the A&P grocery stores. And I can still picture the cover of what I think was Volume 4, with its weird green background (now confirmed through the magic of Google, see photo to the right) and an image of a chemist holding a test tube up to his eye. Right then, in first grade, I knew that's what I wanted to do, and the subsequent childhood variations (pilot, astronaut, engineer, architect) about that path were never very large.
I was careful to put 'non-intellectual' in quotations above. To be sure, my Golden Book Encyclopedia was a far cry from Julian Schwinger systematically working his way through the Encyclopedia Britannica and then the New York Public Library. But I was still very proud when I used my Golden Book knowledge when I was 5 or 6 to explain to my father's friends what the differential was on a car and why you needed it. This tight coupling between "book learning" and understanding the real world around us is precisely the intellectual engagement which so fascinates me and which drove me to experimental physics. I know that I would be a much better experimentalist if I had 1% of my father's (trade school derived) mastery of mechanics, electricity, plumbing, heating and cooling systems, etc., and as a result I have a real antipathy towards those who use a very narrow definition of 'intellectual' to establish some sort of academic hierarchy (see also Chanda's post on the silly genre prejudices about 'fundamental' physics versus more applied studies).
The hard work of my parents meant that we were able to live in solidly middle class suburbs (of Milwaukee, Wisconsin), and therefore take advantage of a fairly good public school system. Given that I was oriented towards science from a very early age, the most likely perturbation would have been away from this state (after all, what fraction of high school graduates become practicing scientists?), but I encountered very few bad teachers along the way. Somehow in first grade I was directed towards a book on how rockets work, which tried to explain action and reaction by what happens when you a squeeze a bar of soap and it squirts out of your hands. Hardly the best explanation, but even in questioning it I was learning something. In second grade I found a wonderful book of science experiments you can do (I recall it was from UNESCO; I bet this is it). I now know it confused air drag with air pressure, so it wasn't perfect, but following its instructions to study evaporation or make a working barometer was fascinating. I think it was this same book that also led to my first safety violation in experimental physics: In describing how sound propagates in dense materials, it noted that American Indians were able to detect oncoming trains many miles (kilometers) away by placing their ears directly on the railroad track. Well, on my walk to school I crossed a railroad track, so I had to do the experiment, and this was duly reported to the teacher by a classmate, who wrote a very concerned note to my parents (my protestations of scientific persecution not withstanding). Her mistake was giving the note to me to bring home; my mistake was throwing it in the ditch... Somehow the subsequent fallout from these cascading bad decisions didn't deter me from continuing my pursuit of science.
Other than this isolated incident, the pattern of encouragement from these 'ordinary' schools continued. A 4th teacher who introduced me to different number systems. A 5th grade teacher who gave me a 'programmed learning' book on rudimentary set theory. A 6th grade teacher who taught me about logarithms and how to use a slide rule. A shop teacher in 9th grade who taught us about phase in AC circuits (really! And I still remember his description of the vectors in the R and L directions as being like horses of different strength, the resultant is the direction the wagon is going to go...).
I know Chanda and others mentioned the role of science fiction (in particular Robert Heinlein) in expanding their horizons; this was also true for me. Heinlein's oft-repeated Calculus Made Easy). I'm sure that it was also through Heinlein that I first became aware of some place called Caltech, which quickly became the place I wanted to go to college. This became even more true after I attended a NSF-sponsored summer institute in nuclear physics at MacMurray College, where I was introduced to the Feynman Lectures on Physics. I was so grateful when my parents let me purchase my own copy from the University of Wisconsin bookstore, especially given the extravagant price at the time ($9.95 for volumes I and II, $8.50 for volume III; these same very tattered hardbound volumes are within an arm's length as I type).
In reading Yidun Wan's post I was struck by his statement "So again, I have to say: 'I simply followed my destiny.'" I often feel that I have done the same, but in the sense that a light ray being bent by a lens is following its 'destiny'. That is, a very definite principal of least action on my part has combined with some extraordinary luck to position me where I am today. I applied to only three undergraduate schools (Caltech, Reed and Wisconsin), only one(!) graduate school, did not have to actively seek my first postdoc, and was asked to apply for the Columbia position I currently hold. At each of the stops along this path I was the beneficiary of some extraordinary mentoring (Caltech- Tom Tombrello, Berkeley- Ken Crowe; Pennsylvania- Sherman Frankel, Columbia- Shoji Nagamiya).
At the same time, it would be unwise for me to minimize the enormous amount of hard work required for a life in science. If you are simply a careerist, then there are far easier ways to make much more money. You have to have sort of personality that 'forces' you to invests the time (sitzfleisch) because you there is something you really want to know about Nature. There is ample evidence that this discovery process must be the most addictive substance around- in a typical career you get only a few 'hits' of the drug, but they are easily enough to keep you going. In my case, I would estimate one or two such hits on my thesis, one as a postdoc and perhaps two as a junior faculty member. The incredible thing about my time on the PHENIX experiment at RHIC is that the hits just keep coming. It's been an honor and a privilege to be associated with such an enterprise, and I can't wait to see what's in our next data set.
The superficial words I've written here perhaps convey a trajectory of extraordinary luck, beginning with a stable childhood located in the sweet spot of the space age. Indeed that's how I think of my career (so far). And of course the very pinnacle of the space age was July 20, 1969, when Neil Armstrong stepped out of the Lunar Module and spoke his immortal words. I vividly recall watching this on a small black-and-white television outdoors on a boat dock in Ontario, and taking immense pride in the praise of our Canadian hosts "You Yanks really did it right". Yet that joy was tempered with enormous grief, as my brother Mike, two years my junior, avid rocketeer and constant companion in tinkering, model building and general boyhood carousing, was not there to share in the moment, having been killed in a traffic accident just a month previous. I am not one for (public) introspection, and initially did not intend to include these remarks. But after some thought I decided that if I was to take advantage of Bee's hospitality and honestly describe those influences that led me to physics, I should avoid selection effects and include all those things that impact on the human condition. While it's clear to me that I had been interested in science and mathematics from my earliest days, it was not until Mike's death that I realized it was time to take this thing called school seriously in order to reach the opportunities that were out there. Only now do I realize (thinking about things as a parent) how difficult is must have been just two years later for my parents to send me off to a school they had never heard of 2000 miles from home. I take some comfort in knowing that the presence of my younger brother Steve at home was a great source of comfort to them as their prodigal son wandered through academia to his current position.
I already mentioned taking advantage of Bee's hospitality, and don't wish to further abuse the reader's interest, so I will avoid rambling on about many other thoughts that preoccupy me (that status of heavy ion physics, why I became an experimentalist, working in large collaborations, academic prejudice against alternative career paths, etc.) But no account of why I am who I am today would be complete without acknowledging the tremendous support of my loving wife Mary, and the joy we take from our sons Thomas and Kevin. I am hardly a role model for parent of the year, but I find inspiration from the existence proofs out there of those who combine a life in science with exceptional parenting. It is possible, and it provides a wonderful and essential balance to the intensity of scientific investigation.
Bill Zajc is a physics professor at Columbia University. He received his BS in physics from the California Institute of Technology in 1975, and his PhD in physics from the University of California at Berkeley in 1982. From 1997 to 2006 he was the spokesperson of the PHENIX experiment at RHIC. Since stepping down as spokesperson last December, he has been using his newly-found free time to answer the mail messages he has been neglecting for the previous decade.
See also the previous contributions to the inspiration-series by
and my related guest post at Asymptotia 'Sabine Hossenfelder: My Inspiration' (also available as pdf-file).
Henri Poincaré
Today is the birthday of Henri Poincaré. Physicist know the Poincaré group of translations and Lorentz transformations, and the Poincaré conjecture about the topology of 3-spheres became widely known last year as the one millennium problem that has been its proofed by a reclusive Russian named Perelman.
But the man behind these concepts is probably not as well know as he deserves to be, considering that he contributed enormously to diverse areas of mathematics and physics. He is better known in France, where he was born on April 29, 1854, in Nancy in Lorraine, but beware: If you see a place, or street in France called Poincaré, it is most probably named after his cousin Raymond Poincaré, who was premier minister and president of the French Republic in 1913-1920.
In physics, Henri Poincaré is most famous for his contributions to the three-body problem, and, of course, to the theory of the electron and the special theory of relativity.
Poincaré discussing with Marie Curie at the 1911 Solvay Congress, while Einstein stands behind. (Source: Solvay Congress 1911)
It is not so easy today to form an unbiased opinion of what Poincaré achieved with respect to relativity, and to give a fair tribute to his and Einstein's respective work and results. That's in part because his original papers about the special theory of relativity are not easily available - I had been searching for a long time before finding some scanned copies to have a glimpse in his 1905 paper, "Sur la dynamique de l'electron", Comptes Rendues 140, 1504-8, and his 1906 paper "Sur la dynamique de l'electron", Rendiconti del Circolo matematico di Palermo 21, 129-176.
It seems that although Poincaré stated a version of the principle of relativity, understood the problems involving simultaneity, formulated the group property of the Lorentz transformations, and postulated the invariance of the laws of physics with respect to different inertial frames, he stayed convinced that all this was a consequence of the detailed dynamics of matter in the rest frame of the ether. A good description of the current understanding of this issue by a historian of science is The Mystery of the Einstein Poincaré Connection, by Olivier Darrigol in Isis 95 (2004) 614–626. Alas, his birthday is to short, even using apparent time, to read all these papers, or the book by Galison, Einstein's Clocks, Poincaré's Maps, which discusses all these topics and contains a biographical sketch of Henri Poincaré...
TAGS: Henri Poincaré, physics, relativity
Saturday, April 28, 2007
FORTRAN at 50, inventor John Backus passed away
For example, I had never heard before of John Backus, until I read his obituary in this week's Nature (subscription required). He was the creator of FORTRAN, the first higher programming language. He passed away on March 17, 2007, at the age of 82. There have been several obituaries published before, i.e. in New York Times, the
The Sydney Morning Herald, or the Guardian.
Backus tried, quite unsuccessfully, to become a chemical engineer and a medical doctor, before he found his vocation in mathematics. Around the time he was finishing his a Master's degree from Columbia University, he visited a showroom exhibition of IBM, where the company presented its latest computers. He talked to some of the representatives there, and at the end of the day, he had a job at IBM.
At that time, in the early 1950s, IBM had started to build and sell computers in series. While hardware thus was more easily available - at least for big universities and companies, or governmental institutions - the problem of programming these computers became critical. Programs had to be written in machine code, in the series of zeros and ones the computer could understand, and this was a tedious and error-prone task, which required much training and could done only by experts.
The IBM 704 computer room at Lawrence Livermore, October 1956. The FORTRAN compiler was developed by John Backus to write programs for this computer. (Source: Lawrence Livermore National Laboratory, Historical Computer Photos
So, Backus had the idea to develop a program that would be able to translate some formal description of an algorithm into the right series of zeros and ones, the machine code the computer would operate with. This was how FORTRAN; the FORmula TRANslator, came into being. The FORTRAN compiler was released for general use with the IBM 704 computer just 50 years ago, in April 1957.
The title page of the IBM 704 Fortran Manual with an autograph by John Backus himself and the names of the people who worked on the first Fortran compiler. (Source: www.fortran.com)
By some curious coincidence, I never actually used FORTRAN for scientific computing. I had landed on an island of C/C++, while everyone else around me was constantly relying on FORTRAN for running simulations or coding small programs to find a quick numerical solution to some mathematical problem. I only realised that it had some funny formal features, for example with respect to the line length, which made me some headaches when I once tried to write a small program in FORTRAN. But once you realise that, actually, this compiler is a reliable tool back from the stone age of electronic computing, you probably can be tolerant with such idiosyncracies.
More about Backus can be found in the IBM Archives.
Here is an iteresting text about The history of the FORTRAN programming language.
Tags: John Backus, FORTRAN
Friday, April 27, 2007
Without Time
I have a friend (who shell remain unnamed, but you occasionally find him in the comment section...) with the habit to always come to late, at least 15 minutes. He is the truest academic that I know, and the 15 minutes are a part of his personality.
Here at PI, coming to late to a seminar or a meeting is significantly tougher, because your BlackBerry beeps relentlessly and reminds you of your slackness (that's the true reason why we get one). But still, it is possible to be late. The easiest way to achieve it is to make a detour via the kitchen to grab a coffee. (You must know that our executive director Howard Burton made 'the importance of coffee and good food' really clear to the architects, and so it became a priority for the building, as you can read here. )
If that coffee detour doesn't take enough time, it is advisable to take the elevator, which - as everybody will confirm - is the slowest elevator in the whole world. But this too is of course not a bug but a feature, and belongs to the design of the building: the intention is to support communication among researchers in 'an abundance of natural light' and so on and so forth.
Indeed, even with the BlackBerry we are pretty successful with the delay tactics I'd say. In fact, hardly any seminar or colloquium starts in time. But actually, I can't recall any institute or department for theoretical physics where this was the case...
... except back in Germany, where we'd just always start late in time. It is called the 'academic quarter' (das Akademische Viertel) and it's announced with a c.t. after the seminar time - an abbreviation for 'cum tempore', the Latin expression for 'with time'. That is, 3 c.t. means actually 3:15. The exceptions are meetings announced with s.t., meaning 'sine tempore' , Latin for 'without time'. I found this nice photo on Wikipedia which shows a plate at Lund University (Sweden) announcing the entry into the realm of academia
For me, one of the most obvious differences between Europe and North America is how much faster time seems to run over here. Most of the time, I am not in time, but without time, even if not outside time. |
And now I've successfully killed time. Weekend is close, and on Friday we have our wine and cheese... (the importance of good food, you know).
A nice weekend to all of you, hopefull one 'with time' :-)
Aside: My lesson of the day is that Google has something called SafeSearch that you should turn off before you expect to find any hits for a term containing 'cum'. But if you do so, you'll find a truly astonishing amount of Latin texts.
Wednesday, April 25, 2007
Happy Birthday Wolfgang Pauli
Therefore, the lunch remark of the day is: did you know that today is Wolfgang Pauli's birthday?
Wolfgang Pauli was born on April 25th, 1900 in Vienna. After receiving his early education in Vienna, he studied at the University of Munich under Arnold Sommerfeld. He obtained his doctor's degree in 1921 and spent a year at the University of Göttingen as assistant to Max Born and a further year with Niels Bohr at Copenhagen. (What I always liked most about quantum mechanics is that I know how to pronounce all the names of the people.)
Pauli is most famous for the exclusion principle which states that identical fermions (like electrons) can not occupy the same state. Thus, fermionic stuff can not clump together arbitrarily, and has an inherent stiffness. Among other things, the Pauli exclusion principle explains why electrons form nice shells around the atom core instead of all sitting in the lowest level, thus explaining the variety of chemical elements.
Wolfgang Pauli received the Nobel Price in 1945 "for the discovery of the Exclusion Principle, also called the Pauli Principle".
There are a lot of entertaining stories around Pauli, which is why he makes a good lunch topic. Among other things, he was known for spoiling experiments by simply being present in the room, an effect that was dubbed the 'Pauli-effect'. Allegedly, Otto Stern even banned Pauli from his laboratory to avoid the Pauli-effect, despite their friendship.
Wolfang Pauli was also known for ruthlessly criticising the work of his colleagues, from which the famous quotation stems
"This isn't right. This isn't even wrong."
("Das ist nicht nur nicht richtig, es ist nicht einmal falsch!")
Now let me publish this post... just in time for lunch. Have a toast to Pauli!
Monday, April 23, 2007
The nabla symbol is used in maths (and physics of course) to denote a differential operator. It was introduced by Hamilton around 1837. Its name apparently goes back to a joke by Maxwell. According to Wikipedia, W. Thomson wrote in 1884:
"I took the liberty of asking Professor Bell whether he had a name for this symbol and he has mentioned to me nabla, a humorous suggestion of Maxwell's. It is the name of an Egyptian harp, which was of that shape"
I am kind of glad he didn't suggest to use the Greek name 'psaltery' as I admittedly have no idea how to pronounce it. You might be interested to hear though that it makes an appearance in the bible, Psalm 33:2
"Rejoice in the LORD, O ye righteous: for praise is comely for the upright.
Praise the LORD with harp: sing unto him with the psaltery and an instrument of ten strings. "
The word 'operator' is a very sophisticated expression for a thing that assigns things to things. The telephone operator for example, assigns incoming calls to the desired connection. Its correct mathematical notation is
An operator can be almost everything. Your kid who never tidies up is an operator that assigns toys to places in your living room. If you buy tickets for the opera, the online booking system is an operator that assigns seats to the audience.
A differential operators specifically acts on functions by differentiating them. The nabla for example, when applied to a scalar field, gives the gradient of that field. If you think about the scalar field as an altitude in a mountain range, then the gradient points towards the direction where the increase is the steepest.
Operators are the core concept of quantum mechanics. Quantities that in a classical theories are functions, like the position or energy of an object, become operators. To make something useful out of them, they now have to act on a function - that being the purpose of an operator. In quantum mechanics, it is the well-known wave-function that they act on.
But the usefulness of the operator concept is that one can deal with them on their own without applying them all the time. It's a bit like replacing 'classical' money with a credit card. If you want to see something 'real' you have to 'apply' it to an ATM to get cash. Most often the result is quantized, say, you can only get multiples of $10 or so. You also typically have an offset, a smallest possible amount that you can get. But for most cases, you are fine dealing with the card itself. You have to be a bit careful though if you use it together with other cards, say the club card (payback card, member card, VIP card, whatever) from your local groceries. For your total, it matters in which order you present them at the register. We say that the operators don't commute: the result depends on the order of use.
The nabla is essentially the operator that, when acting on the wave-function, gives the momentum. That is, up to a constant - in this case a relevant constant. But this may be subject of another post.
Saturday, April 21, 2007
Einstein's Bees
Anyway, I only knew that because the recent bee-problem was pointed out to me already last summer, I think by Lubos (I couldn't find the comment though). What is new this April is that the bee-problem got a catchy name: the colony collapse disorder (already on Wikipedia), and is blamed on mobile phones by The Independent: Are mobile phones wiping out our bees?. They argue with the results of a study by German researchers at Landau University:
"Now a limited study at Landau University has found that bees refuse to return to their hives when mobile phones are placed nearby. Dr Jochen Kuhn, who carried it out, said this could provide a "hint" to a possible cause."
The word 'limited' already sounds very suspicious, and indeed the link is more than weak. For one, it is extremely implausible that this effect should have set in rather suddenly last summer. Mobile phone nets have gradually been extended over a far longer period of time. Also, it is very unlikely that such a mobile phone disorientation 'spreads out' as it seems to have done from the USA to Europe, this doesn't make sense at all:
"The alarm was first sounded last autumn, but has now hit half of all American states. The West Coast is thought to have lost 60 per cent of its commercial bee population, with 70 per cent missing on the East Coast.
CCD has since spread to Germany, Switzerland, Spain, Portugal, Italy and Greece. And last week John Chapple, one of London's biggest bee-keepers, announced that 23 of his 40 hives have been abruptly abandoned."
But more importantly, mobile phones are rarely placed in bee hives. If one tries to find out what the researchers from Landau did, it turns out they indeed placed the 'base station of a mobile phone' directly in the bee hive. Now, if you don't speak German, let me be precise here: the German word commonly used for the English 'mobile phone' (or cell phone) is not 'Mobiltelefon', but 'Handy' (also written 'Händi' in best Denglish). The device the researchers used is not a cell phone, but a cordless home phone. What was placed directly in the bee hive was the base station of that phone.
An very conscise description of their experiment is available online. Unfortunately, it is (except for the abstract) in German. But even if you don't speak German, look at the pictures and illustrations
Verhaltensänderung der Honigbiene Apis mellifera unter elektromagnetischer Exposition
There is follow-up article in Spiegel who tried to clarify the misinterpretation of the researcher's results (again in German unfortunately): Werden Bienen tot telefoniert? (Are Bees phoned to death?), which also quotes Prof. Jürgen Tautz, bee-researcher at the university Würzburg: "I am sure: a healthy, not stressed, bee colony will not be affected by cell phone networks."
Ah - I just realized this wasn't even the reason for me writing. No, I meant to comment on the quotation that has been attributed to Albert Einstein in this context:
"If the bee disappeared off the surface of the globe then man would only have four years of life left. No more bees, no more pollination, no more plants, no more animals, no more man."
("Wenn die Biene von der Erde verschwindet, dann hat der Mensch nur noch vier Jahre zu leben; keine Bienen mehr, keine Bestäubung mehr, keine Pflanzen mehr, keine Tiere mehr, keine Menschen mehr.")
If one does a Google search on 'Einstein Bees' it gives 981,000 results today (two days ago it was only 893,000).
I've read a lot of Einstein stuff, and I can't recall I ever came across something remotely like this. Nowhere could I find a source for this alleged quotation. It seems it goes back to this article by Walter Haefeker (see last paragraph), but there it ends without a reference. It is not listed in any book with Einstein quotations. There are various other people who have pointed out that this quotation is most likely made-up, at least completely unconfirmed see e.g. here, here, or here.
Update April 21st: See also Lubos' post.
Update April 29th: Gelf-Magazine has an article about the alleged Einstein quotation titled 'Albert Einstein, Ecologist?' which confirms my doubts about its authenticity
"Roni Grosz, curator of the Albert Einstein Archives of the Hebrew University in Jerusalem, tells Gelf, "There is no proof of Einstein ever having said or written it." While Grosz notes that it is extremely difficult to disprove a quote, he "could not remember even one reference to bees in Einstein's writings."
Friday, April 20, 2007
Local Warming
Er isses
Frühling läßt sein blaues Band
Wieder flattern durch die Lüfte
Süße, wohlbekannte Düfte
Streifen ahnungsvoll das Land
Veilchen träumen schon,
Wollen balde kommen
Horch, von fern ein leiser Harfenton!
Frühling, ja du bist's!
Dich hab ich vernommen!
Thursday, April 19, 2007
Temporary Blackberry Trouble
Blackberry the gadget is, of course, the first wireless handheld organizer that was able to receive and send email. It's an invention of the Waterloo, Ontario, based company Research in Motion, and earned them a lot of money. So much, indeed, that RIM president and co-chair Mike Lazarides could afford donating $50 million to the University of Waterloo to help establish the Institute for Quantum Computing, and $100 million to establish the Perimeter Institute for Theoretical Physics.
That's the reason why scientist working at the Perimeter get equipped with one of these gadgets once they take over their positions there. And from my somewhat limited experience, these BlackBerries can be quite invasive, as concerns your way of living, since it may happen that you are constantly disturbed by beeps signaling newly incoming emails you have to read immediately ;-).
What brings me back to blackberry, the fruit. Take, for example, this thicket of blackberries:
It is, actually, at the edge of the garden of my parents house. The shrubs provide great fruits in August, and they make a great, impenetrable fence against your neighbours. However, if you do not take care, your lawn is invaded without mercy by this species, and soon, you cannot access anymore the apple trees. It gives you a really cool impression of the hedge around the castle of Dornröschen. So, it's a good idea to peck out the blackberry shrubs entering the garden from time to time, and to make sure to leave no roots behind... That's actually how I spend last weekend, when I visited my mother and she had already prepared a quite a long list of things to do in the garden...
The lesson from this is clear: Blackberries are delicious, and BlackBerries are great. You just should make sure they don't take over your garden :-)
Figure Credits: Wikipedia
TAGS: BlackBerries, blackberries
Wednesday, April 18, 2007
To promote spring feelings, 3Dchem has chosen SEX to be the molecule of the month March 2007: you can play around with different positions using their nice java applet.
According to the NICNAS fact-sheet, everything that contains more than 20% SEX is hazardous:
"Under normal conditions (20°C), there is enough moisture in the air to cause SEX to form carbon disulphide, a highly flammable, toxic gas that is readily absorbed through the skin. [...] It is poisonous but there is a lack of information about its health effects.
SEX is readily absorbed by the skin and is a skin and eye irritant [...].
Signs of high exposure are dizziness, tremors, difficulty breathing, blurred vision [...]. It causes severe skin, eye and respiratory irritation."
So, be careful...
Monday, April 16, 2007
Wireless Power
After a week or so, I gave up. It then occurred to me maybe one or the other reader of our blog understands more about the technical details, so here is what I found out with a lot of open questions.
The issue is how wireless power for home use could work. That is, we are typically talking about distances of some meters or so, over which we want to transmit energy to power technological devices (say, your cellphone), preferably without roasting every human in the room.
To set the base, energy can of course be transmitted without wires. There are generally two ways how this can work:
One is to use electromagnetic radiation. E.g. your microwave does that. Actually, every bulb does that. The problem with this energy transport is if you want to use it over useful distances you either have a sender that broadcasts the energy into all directions, and a receiver that picks up only a part of it. This means a lot of energy is just lost. Or you focus the sender's radiation on the receiver, which means for moving targets you have to track them. (The microwave is a box that avoids radiation loss by reflection, and you don't want to sit in it).
The other possibility is using inductive coupling. In this case, energy is transferred from a sender to the receiver by using the very near field, and the radiation loss is negligible. This technique works pretty good and very efficiently and is in fact used to recharge many devices. The problem is that it only works on really short distances (say, a centimeter or so).
Neither of both ways sounds very useful for wireless power at home. Now, while I was scanning through these articles, I found out that there are currently two ideas on the market that rely on different schemes.
A) The one has been proposed by a group of physicists from MIT, Marin Soljacic (assistant professor of physics), Aristeidis Karalis, and John Joannopoulos (professor of physics). They have a paper on the arxiv about it: physics/0611063. I could also find these slides from a talk one of them (M. Soljacic) gave. There is a news article on BBC, and the story has been echoed with slight alterations, e.g. here, here, or here.
B) The other one is the technology used by a company called Powercast. They have a website that you find here. It it almost void of any information. They have a form that you can fill out and they send you some pdf-files. These again hardly contain any information (except some general explanation about the allowed limits on power density). If you don't want to fill out the form [1], the pdf's are here: 1,2,3,4. They apparently have presented their device on the consumer electronics show 2007, see e.g. here, here, here, or here (they are all more or less identical).
Let me first comment on A: The paper says they propose an 'efficient wireless non-radiative mid-range energy transfer'. Efficient means there is little energy loss. Mid-range means it potentially operates on the distances that we are interested in. Non-radiative means it doesn't use radiation. The idea that they build up upon is a resonance effect. You know that from your car. Your engine causes vibrations, and if you accelerate their frequency changes. If the frequency of the vibration coincides with the resonance frequency of some parts in your car (say the CDs in the glove box) they will also start to vibrate. This does extract energy from the engine, just that for the car this is a totally negligible (though annoying) effect.
Now the technique of A proposes to use a receiver and sender system that are resonant objects. In addition to that they state that they do not use the radiation field for this. Note that a field can very well be time-dependent (oscillating) without actually having an energy flow to far distances. For the sender and receiver they consider two examples: disks and loops. The paper does hardly contain any calculation, it seems there isn't very much one can do analytically with these boundary conditions. But electrodynamics can be treated numerically without too much complications, so that's what they have done. Figure 2 from physics/0611063 shows how that field would look like for the two disks (sorry, I removed the figure due to copyright reasons, see update note below).
Interesting is also Figure 6 which shows how the field gets distorted by a wall (to the right), and by a by sample (the square) that simulates a human (again, sorry, I removed the displayed figure, please check the paper) . In both cases, there is not too much distortion which is really promising. As they write 'the system performance deteriorates [...] only by acceptably small amounts'.
I was wondering why the 'human' isn't placed between the disks, wouldn't you too? But I have to say I find it actually reasonable. As long as you don't hit the resonance frequency you probably don't distort the field too much. A human body is very unlikely to contain resonating parts. Though I wouldn't want to have a pacemaker in such a room. More generally, one should ask how other technological (and metal) objects affect the field. Also, what does the field look like if sender and receiver are not parallel to each other?
But okay, I thought, great. So far I can make sense out of this. But this is the static configuration, in which case there is not really a sender or receiver. It's just two coupled systems. But to describe the realistic situation, one disk (loop) has to be the source that 'powers' the other one. The above figure is perfectly symmetric, so it can't describe this situation.
In particular the question is where is the energy flow localized in that case? I mean, energy is a locally conserved quantity. It has to get from the sender to the receiver somehow. My naive guess would have been, it takes place in that cylindrical part of space whose end-caps are the sender and receiver - this intuition relying on the simple fact that photons like to travel in straight lines. I was looking for something like the Poynting vector of that field, but couldn't find anything. The only 'explanation' I found was from Howstuffworks, which says:
"Electricity, traveling along an electromagnetic wave, can tunnel from one coil to the other as long as they both have the same resonant frequency. The effect is similar to the way one vibrating trumpet can cause another to vibrate."
This, excuse me, is simply bullshit [2]. We're talking about a classical system, energy doesn't just 'tunnel' somewhere. The vibrating trumpet transfers its energy via air molecules. Try it without air, you'll see. (You also find the tunnel-explanation in the BBC News article). In this article at physorg, you will find the statement 'Most of the energy not picked up by a receiver would be reabsorbed by the emitter' which doesn't make sense to me either. Photons don't just turn around and fly back if they were not absorbed.
The reason why this puzzles me is that their paper considers as an example a 'useful extracted power' (p. 15) of 10 W (p.16). Now I would expect this power to be transferred between the two loops, that is, it for a diameter of 30 cm, it is distributed over a surface of roughly 1000 cm2. Distributing the power over a surface that large does of course significantly lower the power density relative to that of a cable. But still one finds a power density of 10 mW/cm2 (The FCC limit e.g. in the frequency range 30-300 MHz is 0.2 mW/cm2). One can of course make the loops larger, just that - if you ask me - already a diameter of 30cm doesn't appear so very handy to me.
In addition to this, I have tried to recall how these resonance effects work. In the symmetric configuration (none of both is a source), there is a phase shift between the oscillations of both coupled systems, and energy is transferred periodically from the one to the other. On the average, this does not lead to an energy flow. In case energy is 'used' on one side, an average flow will take place. However, the energy of the total field is typically significantly larger than the fraction that is transferred. I am not sure I understand all the details, but it seems to me that indeed the extracted energy is only a small fraction of the total field. Then, the power density of the total field is even larger than the above estimate, even though a large part of it does not lead to an effective energy flow, but just goes back and forth [3].
I looked at the slides from the talk, and it seems to me that the configurations examined there indeed have a source and a receiver. But since I didn't hear the talk I am not sure, and again I couldn't find anything about the energy transfer. So I wrote an email to the guy who posted the paper on the arxiv, Aristeidis Karalis. He kindly explained:"Think of two penduli connected with a spring. If you move one, energy will be moved to the other and then back and so on. The energy stays in the system and does not leak out. It just jumps from one to the other back and forth." I am not sure I can make more sense out of 'jump' than out of 'tunnel'.
I repeated my question on where the energy flow takes place, but it seems I exhausted his patience at some point (well, I know, I can be really annoying). Interesting is also what he wrote regarding my question why the human sample wasn't placed between the plates:
"The system of dielectric disks is more affected from extraneous objects than the system of loops. I initially made calculations for the 'human' between the two disks, and the numbers were still viable but worse. Therefore, I chose the positioning presented in the paper, because for application where humans are present most probably the loops would be used, while for applications where disks would be used (e.g. optical regime) the materials have much smaller indices and losses."
But as I said above, I actually believe that a human wouldn't make a big distortion because it's unlikely to hit the resonance frequency.
I then looked who's who on this photo, and I thought maybe it would be more helpful to ask Dr. Marin Soljacic. So I wrote him an email, but he didn't reply - at least not yet[4]. And this is where this story ends.
Then let me summarize what I think about A. If there really is very little energy loss, then it seems to me this energy flow has to take place around the axis between sender and receiver and is roughly distributed over a surface of their diameter. If the efficiency of that is indeed almost independent of the sender's and receiver's relative positions and orientations, this means it is somewhat like an automatically working tracking mechanism. The problem is then that the energy density shouldn't be too high between sender and receiver. (Or you'd want to make sure you don't get in the way.) I am not too good with numbers (famous for loosing factors of 106 or so). So I don't know - given the limits on the power density are fulfilled - how long would it take to charge the average device [5]?
Now to B: In essence the idea is using a broadcaster that operates in 900-MHz range with acceptably small power density. They call that the 'omnidirectional power beacon' and it 'will recharge devices within about a 1-meter range' [source]. This energy can be received by a device they call 'power-harvester'. Since there are constraints on the allowed power density, the field can not be too large which means one can only use it to power really small devices. As they say:
"We have a technology that's here today, with FCC approval, that sends RF signals through the air to power very low- power devices directly or to recharge battery-powered devices," said Powercast vice president Keith Kressin. "Our wireless systems can recharge batteries in any consumer device smaller than a cell phone, from up to a meter away." [source]
It seems they actually have working products, and had a demonstration that impressed many people last month. I have to say though, I don't think I would want to work in an office where LED lights start gleaming through energy they extract from the radiation field around me. No matter if you tell me the limits are compatible with what the government demands.
"You can forget their orientation, forget the use of coils; just watch the LED get brighter the closer you place your device to the Powercaster."
This technology seems to have been developed mainly by Dr. Marlin Mickle and collaborators from Pittsburgh. I checked some of his publications, to find out how efficient this power transfer would be. I found a lot technological details about antennas, but not what I was looking for (I could not access all of the papers). If you do better than I, please let me know.
Besides me feeling uneasy with sitting in that power transmitting field, my problem with B is that I am afraid there might be a considerable loss into radiation. In particular, unlike this article from the Alternative Consumer says, this can hardly be very 'green' . The Alternative Consumer essentially repeats Powercast's information sheet that says nice things like 'Powercast Reduces High-tech Waste' because 'Continuous recharging of batteries via the Powercast Wireless Power Platform has the potential to reduce the huge waste stream of batteries to a mere trickle'. Indeed, instead of rechargeable batteries you then use the power-beacon and -harvester, and instead of transmitting power with negligible loss via a cable you radiate it generously into your apartment where most of it goes byebye to outer space.
In addition, I wonder what happens if the guy in the apartment below me installs a 'power beacon' it his ceiling. And my neighbor to the right. And to the left...
To summarize: I wouldn't buy neither A nor B.
Update, April 17th: Yesterday, I sent an email to one of the authors of physics/0611063, Aristeidis Karalis, asking whether it is okay that I display the figures from paper. He replied that the paper is in the publication process and asked me to remove the figures. I was kind of afraid that would happen. So, I am sorry for the inconvenience, but you'll have to look at the pdf-file.
Footnote 1: You can fill in the address fields with x, it works. They sent only the requested files and no spam.
Footnote 2: The use of the expression 'tunneling' is most likely due to a misunderstanding. The electromagnetic field configuration of the proposed system makes use of the Whispering Gallery modes which have an exponentially decaying tail. From the solution of the wave-equation this is similar to the tunnel-effect in quantum mechanics. Just that in electrodynamics the amplitude is that of the electromagnetic field and not - as in quantum mechanics - a probability amplitude. The typical 'tunnel effect' in which a particle 'jumps' through a classically forbidden region has nothing to do with the above described resonance.
Footnote 3: As Stefan pointed out in this comment, the ratio between the transferred power and that of the total field is of order 1000, which means the total power density would be in the kiloWatt range - far above the allowed FCC limits.
Footnote 4: Yes, I checked the junk folder. I found it indeed possible that PI's highly efficient filter discards MIT-senders as spam.
Footnote 5: As my husband just taught me, with a power of 1.5 W it takes 2 hours to charge a common battery of type AA. That is, the transmitted power they considered is very realistic to applications, and going below it makes the scenario considerably less appealing. To meet the limits on the power density, you either have to wait 100 hours, or increase to diameter of the loops to a meter or so.
Sunday, April 15, 2007
Leonhard Euler 300
Leonhard Euler (1707 - 1783) in a 1753 portrait by Emanuel Handmann
(Öffentliche Kunstsammlung Basel, via MacTutor)
Euler has left his imprint in all branches of mathematics, and created some new ones, such as graph theory. He also contributed to physics, astronomy, and engineering - Wikipedia has a list of about 50 topics that are named after him. Ed Sandifer, in the February 2007 issue of his monthly column "How Euler did it", presents Euler's Greatest Hits in mathematics. Wow - so many stuff you have probably heard about: the polyhedral formula, the Königsberg bridge problem, the product formula, the Euler-Lagrange equations... Lubos has a nice post on the relevance of many of Euler's discoveries for string theory.
And, of course, there is the famous formula
about which whole books have been written. When I was thinking about something a tiny bit original to post about Euler, I thought I might try to trace the origin of this formula in Euler's writings. Mathworld gives as source of the full Euler identity
page 104 of Introductio in Analysin Infinitorum, Vol. 1. Lausanne, 1748. Now, this can be searched for in the Euler Archive, and we find it as entry E101: the Introduction to the Analysis of the Infinite, volume 1, where "Euler lays the foundations of modern mathematical analysis". The original text is available online from gallica.fr, and here is what we read on page 104:
There it is: From this can be seen how imaginary exponential quantities are reduced to sines and cosines of real arguments. It is
It's written in a now old-fashioned notation - in fact, the notation "i" was introduced only in 1777 by, guess whom, Euler - and in an even more old-fashioned language - but what it says is timeless!
There are several web sites commemorating Euler's birthday, for example at theMathematical Association of America, the Euler Society, and the Leonhard Euler Tercentenary - Basel 2007.
The Euler biographies at Wikipedia and MacTutor have much information and many interesting links. If you want to read a book about Euler's life and time, Leonhard Euler by Emil A. Fellmann has not too much maths and no technical details at all - but it is a very readable biography, has a good choice of illustrations, and conveys a lively picture of a 18th century life in science and mathematics. And there is even a comic about Euler.
TAGS: Leonhard Euler, Imaginary Numbers
Saturday, April 14, 2007
Black Hole Session
Still, I was really running behind with preparing the talk. The problem was when I realized I actually had time to talk about whatever I wanted, I could not decide on what to talk about. Then I recalled what I found the most exciting when I was a student were not all the things that were known, but the open problems that were left for us to explore. So I thought, instead of talking about all the things we know I would - somewhat unusual for a scientific talk - focus on what we don't know, and where the frontiers of our knowledge currently are. Thus, the title of the talk
Frontiers of our Knowledge
Abstract: Theoretical and experimental physics work hand in hand to broaden our understanding about the universe that we live in and man's place in the world. In the 21st century, nature has given us quite some puzzles to solve, in the microscopic (particle physics) as well as in the macroscopic (cosmology) range. These open questions at the threshold of the unknown have lead theoretical physicists to formulate possible solutions whose experimental tests are awaited soon. I will talk about these current limits to our knowledge, and about the insights that new experiments like the Large Hadron Collider can provide us with. A central point will be the possibility of large extra dimensions and black hole production at the LHC.
If you want to classify my current state of mind, I'd say I'm an high energy physicist trying to become a cosmologist. I think that in the soon future more interests will shift from particle physics towards cosmology, which right now I find a tremendously exciting area. So in my talk I wanted to talk about both, cosmology and particle physics, especially also the areas where they overlap e.g. dark matter searches, and what that has to do with the 'big' questions like: Where do we come from? What are we made of? (Why am I spending my Saturday at work?)
Well, at least that was the idea. But I have never before given a talk about cosmology (I don't even know what an 'erg' is. Luckily, nobody asked.) I was really kind of nervous (in addition you should know that this lecture starts at 10am, and I didn't have any coffee because due to some problem with the key cards I couldn't get into my office.)
PI's public outreach program is organized by Damian Pope, who told me the format is rather casual, and the physics knowledge of the audience often pretty mixed. So I thought the best would be not to use too many equations, but to really explain every detail (be honest, usually you don't do that since everybody has seen this figure a million times). Bruno made a very nice introduction, and I looked at the large seminar room getting fuller with people. You're not going to believe it, but soon all seats were taken. In fact, after 15 minutes, Damian asked me to interrupt my talk so we could change into the big lecture hall. As I said to Bruno: I think I'm in the wrong movie.
As you can guess, my timing for the talk was a complete disaster. I had to skip the biggest part of the second half, and I had to promise I would put the slides online, so here they are:
Frontiers of our Knowledge (Powerpoint Presentation, ~20 MB)
I am afraid the size of the file is rather large because it has a lot of photos. I have thrown out the movies that I showed, you can download them here:
I believe in recycling, so part of what I told today is based on posts I have written here, in particular Dark Matter, The World's Largest Microscope, Anomalous Alignments in the Cosmic Microwave Background (piecewise), Micro Black Holes and Extra Dimensions.
People had a lot of questions. The best question was without doubt: Do you know what caused the big bang? It was a good question, because it didn't ask what caused it, but if I know it. It happens only rarely that I can clearly answer a question with yes or, in this case, with no.
If I find the time, I will write a summary of the talk sometime next week, if you will find it, then you will find it here.
Overall seen, giving the lecture was a great experience. In fact, I volunteered to do it again...
Friday, April 13, 2007
Einstein reloaded
Einstein on the beach in Santa Barbara, 1933 (?) (Santa Barbara Historical Society, and Caltech Archives)
It seems that Isaacsons book is strong about Einstein's time in the US, but I am not sure if I want to take the time to read through another 700+ pages Einstein biography. I found Jürgen Neffes recent book a very good reading, with a well-balanced mix of the man and the science, and taking into account now available sources about Einstein's personal life. An English translation is about to appear as "Einstein: A Biography". And for a comprehensive and authoritative exposition of Einstein's scientific work, I still know of no match to Abraham Pais' "Subtle is the Lord".
Einstein with astronomer Charles St. John at the Mt. Wilson Observatory in 1931, examining the apparatus for the (unsuccessful) measurement of the gravitational redshift in the solar spectrum. (The Observatories of the Carnegie Institution of Washington, in: Centennial History of the Carnegie Institution of Washington, p. 142)
Anyway, the TIME magazine excerpt of Walter Isaacsons book is accompanied by a sort of "Einstein FAQ": 20 Things You Need to Know About Einstein, answering questions from "Was Einstein a slow learner as a child?" (he was slow in learning how to speak) and "Did Einstein flunk math?" ("I never failed in mathematics") over "Why did it take so long for Einstein to get a Nobel Prize?" (a longer story) to "Was Einstein disillusioned at the end?" (no, he wasn't).
It is definitely worth a click, if only for the wonderful collection of photos, most of which are not those that one usually sees!
TAGS: Albert Einstein, Biography
Thursday, April 12, 2007
Is time an illusion?
From the comment section:
Roberto: The unidirectional time in the equations of physics is constructed from the original, circular time.
(now that explains everything)
Guest: does time really exist? Not in the least. Time is a construct. Created by mankind to assert ourselves over the other dimensions. We have freed ourself from the laws of physics and created a new prison, time.
(Gee, I didn't even notice we freed ourselves from the laws of physics. That's what can happen if you live in a small city in west Ontario - someone could have told me!)
Guest: if you ever get the opportunity, use DMT (dimethyltryptamine). you will see far beyond the illusion of time and realize many things that cannot be expained.
(Fat chance)
Guest: Time is an invention of convenience. Kind of like x^^0 = 1 .
(Aside: this is not an invention of convenience but a consequence of smoothness)
Guest: It's a tautological question. Time is what's measured by a clock, just as intelligence is what's measured by an IQ test.
(Comes back to the point that the question, as formulated, is essentially empty.)
Eric: Human sentience requires this illusion to give us the illusion of free will.
Robert: there is no such thing as time, instead it should be thought of as the cycle of mater and energy from light to total entropy to highly energized quantum materials which all together form the macro world
(thats what happens if you 'think horizontally')
Pierre: If we are going to think about time, shouldn't we first ask ourselves "are thoughts real?".
(I link therefore I am).
Jeff M: It doesn't matter - the question is moot.
(Thanks to Jeff M for enriching my vocabulary, I agree. Will try to use 'moot' from now on instead of 'nonsense'.)
pachorazy: if we change our perception of time can we change how fast we age?
(and how do you measure 'fast' if not with 'time'?)
Stuart: I suppose that it does not matter. Time is how we perceive it. What it may theoretically be has no effect on how it IS for us. So... it is what it is.
letibenson: Time is an allusion and here is why-- our congress can tell us when we need to set our clocks forward or back by an hour. If time was real it would be out of there hands
tculp: If we break down the question, we have an initial question - what is illusion?
Time flies like an arrow, fruit flies like a banana. (From the book "Instant Physics")
Alex: Time is a man-made idea, it is a construct of human society used to make life more convenient and easy.
Gary: It might be time to go back to the Greek philosophical definition of the universe and work our way forward again.
(have fun, say hello if you arrive in the 21st century)
Robert: the fascination that many people have these days with wanting to believe that everything happens all at once, there really is no time.
JD Bailey: Time is not an illusion. Time is a multidimensional relationship.
Jim: Life is illusion and time comes from life.
Ric: One of the secrets of TIME, which I have realized, is that TIME itself is the constant we call "infinity".
Erika: And what about killing time?
Jana: Time is fake. Have a nice day.:)


text:
This week, take in some history and get pampered at one of Delaware's most historic villages.
Where: The Inn at Montchanin Village & Spa. 514 Montchanin Rd., Montchanin, DE. 302-888-2133 or www.montchanin.com
The DuPont Suite - Advertisement -
What's special: This 19th-century hamlet in the Brandywine Valley is listed on the National Register and has received numerous awards. The property offers a slice of historical heaven with 21st-century perks. It's home to 11 meticulously restored buildings dating from 1799 to 1919 surrounded by beautiful gardens. Twenty-eight unique guestrooms and suites are appointed with period furniture. The suites have spacious sitting rooms with fireplaces, private gardens, and marble baths. The on-site Krazy Kat's Restaurant is housed in a renovated blacksmith's shop complete with one of the original forges — it's known as much for its creative cuisine as its whimsical décor. The inn, a member of the Select Registry: Distinguished Inns of North America™, is close to museums, shopping, wineries, golf courses, battlefields, and historic sites.
The deal: Stay one night and get 50 percent off the second night's stay when booking from Sunday to Wednesday. Guestrooms range from $192 to $244 and suites from $290 to $399 (tax not included).
When: Valid through October, 2010

subset: commoncrawl


text:
Great Tutorial / Book for Python
Geschreven door
op .On my quest to adapt my programming skills to the Python language, I ran across a great ebook / tutorial, Dive Into Python. Although it has some pretty complicated examples, where I would have preferred simple examples, it's still a great resource. It is written for experienced programmers in mind, so it's not supposed to be easy... just effective.


text:
The ContextMenu Package
The ContextMenu package is a suite of tools for controlling and customizing the display of context-sensitive menus in Maple. When a user selects a Maple expression, a menu appears in the Context Panel with a customized set of actions that can be performed on this expression. This is a context-sensitive menu. The user may then choose one of the listed actions and the associated command is invoked on the selected object. With the ContextMenu package, you have the option of building an entirely new set of context-sensitive menus or adding to the existing set of menus. The package enables you to add entries to context menus, disable and re-enable existing menu entries, set the criteria governing when an entry should appear, and programmatically test the behavior of your customized menu system.
The following is a brief introduction to some of the key features of the ContextMenu package. For more information, consult the ContextMenu help page.
Building a Context Menu module
The information necessary for building a set of context-sensitive menus is encapsulated in a context menu module. This is a Maple module with a specific set of package commands for adding to and customizing the menu.
The built-in context menu module is accessible as ContextMenu[CurrentContext] .
type( CurrentContext, `module` );
To create a customized context menu system, you must begin by creating a context menu module. This can be done in either of two ways.
First, you can create a brand new, empty module with the ContextMenu[New] command.
CM1 := New():
type(CM1, `module`);
Alternatively, you can make a copy of an existing context menu module and add to the entries already present, with the module's Copy command. The following example illustrates how to make a copy of the Maple built-in context menu module, ContextMenu[CurrentContext]:
CM2 := CurrentContext[Copy]():
type(CM2, `module`);
Customizing a Context Menu module
Adding An Entry
Having created a context menu module, you naturally want to customize it. Adding an entry to the context menu with the Add command is quite easy.
CM1[Entries][Add]( "Multiply by 2", "2 * %EXPR", numeric);
The above entry has added an entry "Multiply by 2" to the set of entries in the context menu module CM1. The third parameter, numeric, indicates that this menu entry should appear in the context menu only if the object that was selected had this type. The second parameter describes the action (multiplication by 2) that should be printed in the worksheet if this entry is selected. The symbol %EXPR is a special placeholder for the selected object.
Submenus and Batch Additions
It is useful to group related menu actions in a submenu. You can specify a submenu with the optional submenu parameter to Add. The following places the "List To Set" menu entry in a submenu, which is accessible from the top-level menu by the name "Conversions".
CM1[Entries][Add]( "List To Set", "convert(%EXPR, set)", list, submenu=["Conversions"] ):
However, when filling a submenu with several entries, it becomes tedious to supply the submenu parameter each time, so the tool to use is AddMultiple. This allows you to add several menu entries at once while passing the same optional parameters to each.
CM1[Entries][AddMultiple]( ["List To Array", "Array( %EXPR )", list], ["List To Expression Sequence", "op(%EXPR)", list], ["List To Product", "convert(%EXPR, `*`)", list], ["List To Sum", "convert(%EXPR, `+`)", list], submenu=["Conversions"] ):
Installation, Use, and Saving
Having customized your context menu module, you can now install it as the active menu system with the
ContextMenu[Install] command. After installation, your customized menus should appear when
selecting Maple output.
Test that the context menu has been properly installed by selecting the output of the following commands.
[1, 3.0, q, Pi, 7/2, {a,c}];
Once you have customized your context menu system, you can save it to a Maple repository for later access. This is accomplished with the ContextMenu[Save] command.
Note: For the following example to work, the directory "/home/maple/lib" must be replaced with the name of lib directory of the Maple installation or with the name of a directory containing a writable Maple archive, see ?march.
Save(CM1, "/home/maple/lib");
Further Customization: Inside a Context Menu module
To learn more of the features offered by the ContextMenu package, it is necessary to acquaint yourself with the structure of a context menu module.
The most important part of a context menu module is, understandably, its collection of menu entries. The Entries subpackage of a context menu module stores the entries to be displayed together with their criteria for display. The most frequently used commands are Add and AddMultiple , which permit new entries to be added to the context menu system.
Also useful are Disable, which prevents an entry from appearing in a context menu until explicitly re-enabled, and Enable, which enables or re-enables a disabled entry.
CM1[Entries][Disable]( "Multiply by 2" ); CM1[Entries][Disable]( ["Conversions", "List To Sum"] );
CM1[Entries][Enable]( ["Conversions", "List To Sum"] );
A query is a Maple procedure that retrieves some piece of information about the selected object. Queries are generally used to specify additional tests, beyond the type check, for a menu entry to pass in order to be displayed. However, they may also be used by other queries and by entry generators. The most frequently used commands in the Queries subpackage are Add and Run.
CM1[Queries][Add]( "Variables", proc(e) indets(e, 'name') end proc );
CM1[Queries][Add]( "NumVariables", proc(e) nops(CM1:-Queries:-Run("Variables", e)) end proc );
When writing context-sensitive menus, it is frequently necessary to request some piece of information from the user that is dependent on the selected expression in some way. For example, given the expression x*y, if you select a menu entry Differentiate, you might expect to be asked to choose which of the two variables to differentiate by.
This functionality is provided by the EntryGenerators subpackage. Essentially, an entry generator is a procedure that accepts an expression and returns a list of menu entries. The following demonstrates the creation and use of an entry generator. Like the placeholder %EXPR, you can specify placeholders for values returned by an entry generator with the names %ARG1, %ARG2, ....
CM1[EntryGenerators][Add]( "VariableList", proc(e) local x; [seq([ convert(x, 'string'), [x] ], x=indets(e, 'name'))] end proc );
CM1[Entries][Add]( "Differentiate", "diff( %EXPR, %ARG1 )", algebraic, entry_generator = "VariableList" ):
You can test that the entry generator above works properly by selecting the output below.
See Also
ContextMenu, ContextMenu[CurrentContext], ContextMenu[Install] , ContextMenu[New]
Return to Index for Example Worksheets
Download Help Document


text:
From April 11th to May 14th at the Showroom Puntoluce
Underwater Design by Giancarlo Zema is the attractive exhibition promoted by Puntoluce, the showroom of Roberto Catellani in the heart of Bergamo, renowned as a reference point for good lighting. This perfect location will let the organic creatures of the architect Giancarlo Zema move and grow through an ideal seabed: the sinuous Leaf Collection in DuPont™ Corian® and the mysterius Bright Wood Collection for Avanzini Group, able to suggest unique and surprising atmosphere; the sprightly Ring Collection, table chair and stool for Giovannetti, that with its object-holder holes sprouts from the rocky bottom; the sculptural pressure Collection, two tone porcelain glasses and bottle-holder for Bosa; the smart SimoGi, rounded object-holder in DuPont™ Corian® for Bsolid; then, in the sea swim the coloured fishes of the Fish radiator for Runtal and the Shark handles for Ghidini. An extraordinary opportunity to introduce the public preview of the last creation in DuPont™ Corian® for LumineXence, the new floor lamp named "Octopus" of the architect from Rome always attracted by the sea world.
More images & Colors : Click on image to Enlarge


text:
Published by The Theosophical Publishing House, Chennai
Om ! That (Brahman) is infinite, and this (universe) is infinite.
The infinite proceeds from the infinite.
(Then) taking the infinitude of the infinite (universe),
It remains as the infinite (Brahman) alone.
Om ! Let there be Peace in me !
Let there be Peace in my environment !
Let there be Peace in the forces that act on me !
I-i-1-6. In the beautiful city of Ayodhya, in the centre of a pavilion set with gems, together with Sita, Bharata, Lakshmana and Satrughna, was Rama seated, glorified day and night by sages like Sanaka, Vasistha and Suka as well as other devotees, unchanging witness of thousands of modifications of the intellect, delighted in contemplating his own form. At the end of this Samadhi, Hanuman asked with devotion, 'O Rama, you are the supreme being, of the nature of Sat, Chid and Ananda. I desire to know your nature truly for liberation. Please tell me how I can be released from bondage without strain.
I-i-7-14. Rama: Well asked. I shall tell you. I am well established in Vedanta.
Hanuman: What is Vedanta and where is it ?
Rama: The Vedas in all their great extent are my breath, Vedanta is well grounded in them, like oil in sesamum.
Hanuman: How many are the Vedas and how many branches do they have ? Of these what are the Upanishads ?
Rama: Vedas are four, Rig-Veda etc., many branches and Upanishads exist in them. Rig-Veda has 21 branches and Yajus has 109. Sama has 1000 and Atharva has 50. Each branch has one Upanishad. Even by reading one verse of them with devotion, one gets the status of union with me, hard to get even by sages.
I-i-15-17. Hanuman: Rama, sages speak differently: some say there is only one kind of liberation. Others say it can be got by worshipping your name and by the Taraka mantra at Kashi. Others speak of Sankhya-Yoga and Bhakti-Yoga, the enquiry into Vedanta-Vakyas etc.
I-i-18-23. Rama: Liberation is of four kinds: Salokya etc. But the only real type is Kaivalya. Anybody even though leading a wicked life, attains Salokya, not other worlds, by worshipping my name. Dying in the sacred Brahmanala in Kashi, he will get the Taraka-mantra and also liberation, without rebirth. On dying anywhere (else) in Kashi, Maheshvara will utter the Taraka-mantra in his right ear. He gets Sarupya with me as his sins are washed away.
The same is called Salokya and Sarupya. Persevering in good conduct, with mind fixed upon me, loving me as the Self of all, the twice-born gets nearer to me – This is called the three forms of liberation. Salokya, Sarupya and Samipya.
I-i-24-25. Meditating on my eternal form as prescribed by the Teacher, one will surely achieve identity with me like the insects changing into the bee. This alone is the liberation of identity (Sayujya) yielding the bliss of Brahman.
All these four kinds of Mukti will be got by worshipping Me.
I-i-26-29. But by what means is the Kaivalya kind of Moksha got ? The Mandukya is enough; if knowledge is not got from it, then study the Ten Upanishads. Getting knowledge very soon, you will reach my abode. If certainty is not got even then, study the 32 Upanishads and stop. If desiring Moksha without the body, read the 108 Upanishads. Hear their order.
I-i-30-39. 1. Isa
2. Kena
3. Katha
4. Prasna
5. Munda
6. Mandukya
7. Taittiri
8. Aitareya
9. Chandogya
10. Brihadaranyaka
11. Brahma
12. Kaivalya
13. Jabala
14. Svetasva
15. Hamsa
16. Aruni
17. Garbha
18. Narayana
19. Paramahamsa
20. Amritabindu
21. Amritanada
22. Atahrvasirah
23. Atharvasikha
24. Maitrayini
25. Kaushitakibrahmana
26. Brihajjabala
27. Nrisimhatapini
28. Kalagnirudra
29. Maitreya
30. Subala
31. Kshurika
32. Mantrika
33. Sarvasara
34. Niralamba
35. Sukarahasya
36. Vajrasuchika
37. Tejobindu
38. Nadabindu
39. Dhyanabindu
40. Brahmavidya
41. Yogatattva
42. Atmabodha
43. Naradaparivrajaka
44. Trisikhi
45. Sita
46. Yogachudamani
47. Nirvana
48. Mandalabrahmana
49. Dakshinamurti
50. Sarabha
51. Skanda
52. Tripadvibhuti-Mahanarayana
53. Advayataraka
54. Ramarahasya
55. Ramatapani
56. Vasudeva
57. Mudgala
58. Sandilya
59. Paingala
60. Bhiksu
61. Mahat
62. Sariraka
63. Yogasikha
64. Turiyatita
65. Sannyasa
66. Paramahamsaparivrajaka
67. Akshamalika
68. Avyakta
69. Ekakshara
70. Annapurna
71. Surya
72. Akshi
73. Adhyatma
74. Kundika
75. Savitri
76. Atma
77. Pasupata
78. Parabrahma
79. Avadhutaka
80. Tripuratapini
81. Devi
82. Tripura
83. Katharudra
84. Bhavana
85. Rudrahridaya
86. Yoga-kundali
87. Bhasma
88. Rudraksha
89. Ganapati
90. Darsana
91. Tarasara
92. Mahavakya
93. Panchabrahma
94. Pranagnihotra
95. Gopalatapini
96. Krishna
97. Yajnavalkya
98. Varaha
99. Satyayani
100. Hayagriva
101. Dattatreya
102. Garuda
103. Kalisamtarana
104. Jabali
105. Saubhagyalakshmi
106. Sarasvatirahasya
107. Bahvricha
108. Muktika
I-i-40-43. These destroy three kinds of Bhavana (regarding) body, senses and mind respectively as identified with Atman. The best of Brahmanas will become Jivanmuktas if they study upto the destruction of Prarabdha, these 108 Upanishads from a Guru along with the Shanti-pada. Then, in course of time they will get Vedeha-mukti, surely.
I-i-44-52. These 108 are the essence of all Upanishads and can cut away all sins by merely hearing once. These cause release whether read with or without knowledge. One may give away a kingdom, wealth etc., to one who asks, but not these 108 to just anyone – to an unbeliever (nastika), ungrateful, of bad conduct, one against devotion to me, deluded by wrong scripture or lacking devotion to the Guru.
But they shall be taught to one devoted to service, devotee, of good conduct, birth and wisdom. He should be well tested. A Rik verse on this: the goddess of knowledge came to a Brahmana and said 'Protect me, I am your treasure, do not teach me to one who is jealous, dishonest and deceitful – then I shall powerful, but give it to one who is learned, careful, wise and celibate, after examining him'.
I-ii-1. Then Maruti asked Sri Ramachandra thus: Please relate to me separately the Shanti-mantras of the different Vedas, Rig etc.
Sri Rama then said: "My speech rests on my mind … †[Vanme-Manasi….]. This is the Shanti-mantra of the following ten Upanishads forming part of the Rig-Veda:
1. Aitareya
2. Kaushitakibrahmana
3. Nadabindu
4. Atmabodha
5. Nirvana
6. Mudgala
7. Akshamalika
8. Tripura
9. Saubhagyalakshmi
10. Bahvricha
I-ii-2. "That (which lies beyond) is full†[Purnamada ….] – and so on: This is the Shanti-mantra of the following Nineteen Upanishads, forming part of the Sukla-Yajur-Veda:
1. Isavasya
2. Brihadaranyaka
3. Jabala
4. Hamsa
5. Paramahamsa
6. Subala
7. Mantrika
8. Niralamba
9. Trisikhibrahmana
10. Mandalabrahmana
11. Advayataraka
12. Paingala
13. Bhiksu
14. Turiyatita
15. Adhyatma
16. Tarasara
17. Yajnavalkya
18. Satyayani
19. Muktika
I-ii-3. "May (the Brahman of the Upanishads) protect us both†[Sahanavavatu …] – and so on: This is the Shanti-mantra of the following Thirty-Two Upanishads, forming part of the Krishna-Yajur-Veda:
1. Kathavalli
2. Taittiriyaka
3. Brahma
4. Kaivalya
5. Svetasvatara
5. Garbha
6. Narayana
7. Amritabindu
8. Amritanada
9. Kalagnirudra
10. Kshurika
11. Sarvasara
12. Sukarahasya
13. Tejobindu
14. Dhyanabindu
15. Brahmavidya
16. Yogatattva
17. Dakshinamurti
18. Skanda
19. Sariraka
20. Yogasikha
21. Ekakshara
22. Akshi
23. Avadhuta
24. Katharudra
25. Rudrahridaya
26. Yoga-kundalini
27. Panchabrahma
28. Pranagnihotra
29. Varaha
30. Kalisamtarana
31. Sarasvatirahasya
I-ii-4. "May the unseen powers nourish†[Apyayantu ….] – and so on: This is the Shanti-mantra of the following Sixteen Upanishads forming part of the Sama-Veda:
1. Kena
2. Chandogya
3. Aruni
4. Maitrayani
5. Maitreya
6. Vajrasuchika
7. Yogachudamani
8. Vasudeva
9. Mahat
10. Sannyasa
11. Avyakta
12. Kundika
13. Savitri
14. Rudrakshajabala
15. Darsana
16. Jabali
I-ii-5. "May we hear with our ears the auspicious truths of the Vedanta†[Bhadram-Karnebhih…] – and so on: This is the Shanti-mantra of the following Thirty-One Upanishads of the Atharva-Veda:
1. Prasna
2. Mundaka
3. Mandukya
4. Atahrvasiras
5. Atharvasikha
6. Brihajjabala
7. Nrisimhatapini (Purvottara)
8. Naradaparivrajaka
9. Sita
10. Sarabha
11. Tripadvibhuti-Mahanarayana
12. Ramarahasya
13. Ramatapini (Purvottara)
14. Sandilya
15. Paramahamsaparivrajaka
16. Annapurna
17. Surya
18. Atma
19. Pasupatabrahmana
20. Parabrahma
21. Tripuratapini
22. Devi
23. Bhavana
24. Bhasmajabala
25. Ganapati
26. Mahavakya
27. Gopalatapini (Purvottara)
28. Krishna
29. Hayagriva
30. Dattatreya
31. Garuda
I-ii-6. Men who are seekers after Liberation and well-equipped with the four requisite means ! Approach properly, with gifts in the hands, a good teacher who is dedicated, belonging to a good family, well-versed in the Vedas, interested in the scriptures, of good quality, straightforward, interested in the welfare of all creatures, compassionate and learn in the prescribed manner the one hundred and eight Upanishads; study them through listening, reflection and deep absorption continuously; the accumulated Karmas will be dissolved, the three kinds of bodies (gross, subtle and causal) are abandoned and like the ether of the pot when released from its Upadhi, rise to the level of fullness called Videha-mukti. This indeed is the Absolute Liberation (Kaivalya-mukti). That is why even those in the Brahma-loka, get identity with Brahman after listening to the Upanishads from his mouth. And for everyone Absolute Liberation is stated to be (attainable) only through knowledge; not through Karma rituals, not through Sankhya-Yoga or worship. Thus the Upanishad.
II-i-1. Then Hanuman asked Ramachandra: What is this Jivanmukti, Videha-mukti ? What is the authority, means of success and purpose ? Rama said: For a person there is bondage from doer-ship, enjoyer-ship, pleasure, pain etc., — their prevention is liberation in the body. Videha-mukti (liberation without the body) is from the destruction of Prarabdha (operative) karma, like the space in a pot released from the conditioning (enclosing) pot. For both the authority is the 108 Upanishads. The purpose is eternal happiness through the stopping of the misery of doer-ship etc. This can be achieved by human effort just as a son is got by putra-kama sacrifice, wealth by trade etc., and heaven by jyotistoma.
II-ii-1-9. There are these verses: Human effort is said to be of the two kinds: For and against the Shastras – the former gives disaster, the latter the ultimate reality. True knowledge does not come to one from latent impressions through the world, Shastras and the body. Such impressions are two-fold: good and bad; if you are induced by the good, you shall reach me gradually but quickly; the bad ones involved lead to trouble and should be overcome with effort. The river of impression flowing through good and bad paths, must be turned into the good path with human effort – One should fondle the mind-child with human effort. When by means of practice, good impressions arise, then the practice has been fruitful. Even when this is in doubt, practice only the good tendencies – there shall be no fault.
II-ii-10-15. The destruction of impressions, cultivation of knowledge and destruction of the mind, when practised together for long will yield fruit. If not practised together, there will be no success even after hundreds of years, like mantras which are scattered. When these three are practised long, the knots of the heart surely are broken, like lotus fibre and the stalk. The false impression of worldly life is got in a hundred lives and cannot be destroyed without long practice. So avoid desire of enjoyment as a distance with effort and practise the three.
II-ii-16. The wise know that the mind is bound by the impressions, it is liberated when released well from them. So, O Hanuman, practice the destruction of mental impression, quickly.
II-ii-17-18. When impressions die out, the mind becomes put out like a lamp. Whoever gives up impressions and concentrates on Me without strain, he becomes Bliss.
II-ii-19-23. Whether he concentrates on actions or not, when he avoids all the desires of the heart, he is doubtlessly liberated. He has nothing to gain from action or inaction. If his mind is not freed from impressions even Samadhi and Japa cannot give fruit. The highest place cannot be got without silence free from impressions. Sense organs like the eye go towards external objects without voluntary impression but because of the latent impression just as the eye falls voluntarily without attachment on external objects, so the man of wisdom operates in work.
II-ii-24-31. The sages know that Vasana comprises all objects generated by creative faculty of the mind in attaining or avoiding them. The very unsteady mind which is the cause of birth, old age and death is generated by desire for objects in excess. By the influence of Vasana there is the pulsation of Prana, from it comes Vasana (again) like seed and sprout. For the tree of the human mind, the pulsation and Vasana are two seeds – when one dies both die. Latent impressions stop operating through detached behaviour, avoidance of worldly thought and realization that the body is mortal.
The mind becomes non-mind by giving up Vasanas. When the mind does not think, then arises mindlessness giving great peace; so long as your mind has not fully evolved, being ignorant of the supreme reality, perform what has been laid down by the teacher, Shastra and other sources. Then with impurity ripened (and destroyed) and Truth understood, you should give up even the good impressions.
II-ii-32-37. In a Jivanmukta the destruction of the mind is with form – in a Videhamukta it is formless – when you achieve it, the mind with qualities like friendliness will surely attain peace. The mind of the Jivanmukta has no rebirth.
The mind is the root of the tree of Samsara which has thousands of sprouts, branches, fruits etc. I take the mind to be nothing but construction; make it dry in such a way that the tree also is dried up.
II-ii-38-47. There is only one means for overpowering mind. Shooting up of one's mind is one's undoing, its destruction is good fortune. The mind of the knower is destroyed, it is a chain for the ignorant. As long as the mind is not defeated by means of firm practice, the impressions jump in the heart like ghosts at night.
The impressions of enjoyment die, like lotus in winter, for one whose mental pride is reduced and the senses – the enemies – are defeated. One should at first conquer the mind, hands locked in hands, teeth set on teeth and limbs subdued. The mind cannot be conquered without defectless reasoning (methods) by merely sitting, just as an elephant in rut without a goad. The reasons (methods) well-nourished in mind-conquest are knowledge of Vedanta, contact with good people, giving up impressions and stopping of the pulsation of Prana. Those who ignore these and control the mind by force, throw away the lamp and search in darkness by means of soot, also (try to) bind an elephant in rut by lotus fibre.
II-ii-48-50. The tree of mind, bearing the weight of the creepers of thought, has two seeds: the pulsation of Prana and strong impressions. All pervasive consciousness is shaken by the pulsation of Prana – In contrast, by means of concentration the knowledge arises. The Dhyana, its means, is now imparted. Dissolving thought totally in the reverse order, think only of the remaining pure consciousness.
II-ii-51-56. After the Apana sets and before Prana arises in the heart, there exists the state of Kumbhaka (immobility) experienced by Yogins. Kumbhaka in the external form is the fullness of Prana after in-breath disappears and out-breath arises. By repeatedly practising meditation of Brahman without ego, Samprajnata Samadhi will be got. The Asamprajnata Samadhi, loved by Yogins, is (from) the mind giving great bliss after (all) the mental modifications (thoughts) die away. It is valued by sages, being the spirit devoid of the light (of ego), of the mind (of dream) and of the intellect (in deep sleep). This concentration is other than what is not Brahman. Full above, below and in the middle the essence of goodness – this state, prescribed by the Upanishads, is the ultimate reality.
II-ii-57-60. Latent impression is that unexamined grasping of objects by persistent imagination. What one brings into being, through intense dispassion by one's self, is realized quickly, devoid of opposite impressions. Influenced by impressions, a person looks upon those things as reality by the peculiarity of the impressions, the ignorant person sees the spirit wrongly though it does not lose its own nature.
II-ii-61-68. The impure impression binds, the pure destroys birth. The impure one is solid ignorance and ego, causes rebirth. The restful state is like the roasted seed, giving up the (sprout of) rebirth. Can the inner light be sought with chewing the cud of many Shastras, uselessly ? One who remains alone giving up perception as well as non-perception is himself the Brahman – A person cannot know Brahman by merely learning the four Vedas and Shastras, as the ladle cannot taste the food.
If a person does not get detachment by the bad smell of his own body, what other cause of detachment can be taught ? The body is very impure – the soul is pure. When one knows the difference, what purification need be prescribed ? Bondage is by impressions, Moksha is their destruction – you give them up as well as the desire for Moksha.
II-ii-69-71. Give up mental impressions of objects and cultivate pure impressions like friendship; then, discarding even these while acting according to them, putting down all desires, have only the impression of consciousness. Give up these too along with mind and intellect; concentrate only on me.
II-ii-72-77. Contemplate me as devoid of sound, touch, form, taste and smell, eternal, indestructible, without name and family, destroying all suffering, the nature of vision like the sky, the one syllable Om, unsmearing though omnipresent, unique, without bondage, forward, across, above, below, I fill ever place.
Unborn, ageless, shining by myself, not the cause nor effect, ever contented when the body dies away, giving up the state of Jivanmukta, one enter the Videhamukti stage.
So says the Rik: That supreme place of Vishnu the sages see ever – like an eye extended in heaven. The wise and awakened persons, free from emotions, keep it alight.
Om – This is the Upanishad.
Om ! That (Brahman) is infinite, and this (universe) is infinite.
The infinite proceeds from the infinite.
(Then) taking the infinitude of the infinite (universe),
It remains as the infinite (Brahman) alone.
Om ! Let there be Peace in me !
Let there be Peace in my environment !
Let there be Peace in the forces that act on me !
Here ends the Muktikopanishad belonging to the Sukla-Yajur-Veda.


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If you want to be a great leader who attracts quality people, the key is to become a person of quality yourself. Leadership is the ability to attract someone to the gifts, skills and opportunities you offer as an owner, as a manager, as a parent. Leadership is the great challenge of life.
What's important in leadership is refining your skills. All great leaders keep working on themselves until they become effective. Here's how:
- Learn to be strong but not impolite.
It is an extra step you must take to become a powerful, capable leader with a wide range of reach. Some people mistake rudeness for strength. It's not even a good substitute. - Learn to be kind but not weak.
We must not mistake weakness for kindness. Kindness isn't weak. Kindness is a certain type of strength. We must be kind enough to tell someone the truth. We must be kind enough and considerate enough to lay it on the line. We must be kind enough to tell it like it is and not deal in delusion. - Learn to be bold but not a bully.
It takes boldness to win the day. To build your influence, you've got to walk in front of your group. You've got to be willing to take the first arrow, tackle the first problem, discover the first sign of trouble. Like the farmer, if you want any rewards at harvest time, you have got to be bold and face the weeds and the rain and the bugs straight on. You've got to seize the moment. - Learn to be humble but not timid.
You can't get to the high life by being timid. Some people mistake timidity for humility. But humility is a virtue; timidity is a disease. It's an affliction. It can be cured, but it is a problem. Humility is almost a God-like word—a sense of awe, a sense of wonder, an awareness of the human soul and spirit, an understanding that there is something unique about the human drama versus the rest of life. Humility is a grasp of the distance between us and the stars, yet having the feeling that we're part of the stars. - Learn to be proud but not arrogant.
It takes pride to build your ambitions. It takes pride in your community. It takes pride in a cause, in accomplishment. But the key to becoming a good leader is to be proud without being arrogant. Do you know the worst kind of arrogance? Arrogance from ignorance. It's intolerable. If someone is smart and arrogant, we can tolerate that. But if someone is ignorant and arrogant, that's just too much to take. - Learn to develop humor without folly.
In leadership, we learn that it's OK to be witty but not silly; fun but not foolish. - Learn to deal in realities.
Deal in truth. Save yourself the agony of delusion. Just accept life as it is—the whole drama of life. It's fascinating.
Life is unique. Leadership is unique. The skills that work well for one leader may not work at all for another. However, the fundamental skills of leadership can be adopted to work well for just about everyone: at work, in the community and at home.


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St. Martin-in-the-Fields Episcopal Church shares our weekly worship bulletin and announcements as a downloadable PDF. All our worship services during Pentecost will use Rite II from the Book of Common Prayer.
Scriptures for the sixth Sunday after Pentecost
Helpful resources
- Book of Common Prayer (BCP online)
- 1982 hymnal
Did you miss a sermon? Sermons are here. You can watch video, listen to audio, or download an MP3 to your phone or tablet and listen on the go.


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Therefore, if a part needs to be replaced, only original spare should be used. In this way only can we guarantee that your WOLFF will perform as efficiently and safely as always.
WOLFF Parts – Spare Parts International in Heilbronn, with its own warehouse, as well as short decision making paths to the production and service teams, guarantee the efficient handling of your spare parts requests.
WOLFFKRAN GmbH
Austrasse 72, 74076 Heilbronn
+49 7131 9815 0
+49 7131 9815 355


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Where High Quality Doesn't Cost You More
The highest quality hardwood cabinets — solid cherry wood, maple, and oak — are always available and affordably priced at Golden Cabinets, home of Hawaii's largest inventory of fine solid wood kitchen and bath cabinetry.
Wide selections of finely crafted designs, styles and finishes are featured at the Golden Cabinets Inc. showroom located at 2959 Koapaka St.
Cabinets, shelves, moldings and drawers are all available in rich cherry wood, warm maple, classic oak and white finishes. No particle board, plastic or laminates are incorporated into these solidly built natural wood products. All are fitted with handsome, heavy duty, stainless steel fixtures and precision hinges.
The cabinet doors come in a variety of styles, including solid wood and wood with framed glass insets to show off your fine crystal and dinnerware. There is also a choice of glass panels — clear, frosted and etched. A variety of designs to accommodate all kitchen layouts, such as corner cabinets with fold-out doors and Lazy Susans, and cabinets with roll-out shelves, plus vanities and vanity accessories for the bath, can be viewed in the showrooms.
"Cabinets are the first thing you see when you walk into a kitchen, so whether you are building new or remodeling, you want to be sure you are making the right choice," said Golden Cabinets owner Wen Wen Cao.
"And there's no long wait between ordering and installation — one week after you place your order, the cabinets of your choice will be delivered or can be picked up by your contractor.
"We also offer free assembly and design services … just provide the rough dimensions of the room, and we can lay out a cabinet design and configuration for you on the computer in a matter of minutes. Then, if you approve of the basic layout and estimate, we will go to the job site and make the final measurements.
"Because we specialize in cabinets, we have the expertise to help you create a more beautiful and functional kitchen … at a price you can afford."
For information and directions to the showroom, which is open from 8 a.m. to 5 p.m. Monday through Saturday, call Golden Cabinets at 836-8181.


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When you choose Genie® products, you get more than equipment designed for reliability, easy operation, convenient service and uncompromising safety. You also get tailored service and support from a team that understands your challenges. We believe our job is to make your business better. From small portable material lifts to telehandlers, scissor lifts, telescopic and articulating booms, Genie® products offer you exceptional performance, safety and reliability.
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Access fall arrest equipment is available for sale at Professional Safety Services (UK) Ltd through our sales department. We have a wide variety of equipment offer a comprehensive choice for any equipment gaps you may have. Because of this we have continued increase our internal stock levels.
A device which comprises of a retractable lifeline made from synthetic fibre rope, webbing or wire rope that is stored on a reel within a protective housing. The reel is spring-biased so as to wind the retractable lifeline in. Hence, this ensures that the lifeline is always under light tension to give the shortest possible length between the housing and the user. The lifeline tension allows the user to move freely around the work area. Retrieval device comprise of an emergency winch handle for extraction of personal. Because the unit is PPE, it must be inspected in the event of the emergency winch being used.
A tripod is designed to be a temporary anchor in fall protection systems. They need to confirm to standard CE EN795 class B and offer a stable platform for confined space entry to be carried out. Because of this they are a essential part of confined space entry kit.
Winches are typically used to lower and raise workers under tension. Man riding equipment must conform to the standard CE EN 1496 and CE EN 796 for them to be classified as personal protection equipment and not machinery. Hence many pieces of equipment can be mixed up when it comes to selecting the correct equipment in man lifting environments.
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The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.


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The following video is a great example of this philosophy. I added a bunch of pastels onto some KnitPicks Bare Stroll fingering weight yarn (Affiliate Link) and felt like something was missing. I have a container where I combine random acid dye powders leftover from projects (which at the time was mostly Forest Green) and added speckles onto the yarn. This tied the whole thing together, and I think the results are stunning.
The only downside to using leftover dyes is that sometimes I create some colorways that are so beautiful I'd love to recreate them. Recreation is hard when you're not aware of the acidity and proportions of different dyes used. Sometimes the dyebath is fresh for these videos, but frequently I'm using leftover exhausted baths, or presoaks... basically anything that I can reuse!
Want to see more Leave No Dye Behind videos? Check out the following playlist! This is a non-numbered series of videos that show up in random order. Sometimes they're tied to the video where I mixed the dyes, and other times I have no idea where the leftovers came from. No matter what, we have a ton of fun!
This post contains some KnitPicks affiliate links, which means that I earn a commission off of any sales through my link. I have been a KnitPicks affiliate since Fall 2017.


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Celebrate Mother's Day with stories, games, activities and more!
Get ready to celebrate Mother's Day on May 11th! It's a day to show your love and appreciation for mothers and mother figures. Did you know that in US and Canada this holiday is celebrated on the second Sunday of May, but in other countries it can be celebrated on different dates? Join the celebration and head on to animatedmothersday.com, here you will find out about the history of this holiday "The Original Story of Mother's Day", play some fun games and get some cool downloadable activities.
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Grandstream Networks, Inc. is an award-winning designer and ISO 9001 certified manufacturer of next generation IP voice & video products for broadband networks. Grandstream's products deliver superb sound and picture quality, rich telephony features, full compliance with industry standards, and broad interoperability with most service providers and 3rd party SIP based VoIP products. Grandstream is consistently recognized in the VoIP industry for their innovation, affordability and superior value in their products.
Incorporated in 2002, Grandstream has been growing profitably and rapidly since 2003, its first year of product shipment. Grandstream has experienced a strong 2-digit year-over-year compound annual growth rate (CAGR) in revenue since 2003. Grandstream has a comprehensive and expanding portfolio of innovative IP voice and video products, top tier customers, large deployed base, and established distribution channels worldwide.
Grandstream Networks is a private company headquartered in Brookline, MA with offices in Los Angeles, Dallas and China.
Speed Advance is Grandstream's Reseller locatetd in Dubai and whole middle east countries like UAE, Pakistan, Afghanistan and Iraq.


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19th Century French Tapestry
Size: 6'3" x 4'9"
Our antique tapestries date from the 16th-19th century. These items are one of a kind or in limited quantity. We guarantee the authenticity of our listing, and if you have any questions regarding the item above, you can contact our office at (212) 752-0995 and look for Suzanne C. Nagy for expert opinion.
The absence of a condition statement does not imply that the lot is in perfect condition or completely free from wear and tear, imperfections, or the effects of aging. Condition requests can be obtained by contacting us. Any condition statement given as a courtesy to a client is only an opinion and should not be treated as a statement of fact.
Color Disclaimer: Actual colors may vary due to the lighting that was used when taking photos. We try to edit our photos to show the samples as life-like as possible, but we cannot guarantee that the color you see accurately portrays the product's true color.