gcol

Norman: "By itself the string moves little air and has no "acoustic reality"". I like that. How about "That old string don't mean a thing if it ain't got no ping" (I am crudely paraphrasing a line from an old jazz classic). For me, a string is simply the notional boundary envelope of the sum total of harmonic energies that make it ping. It is as physically unreal as the notion of a single bounded physical particle. As a 3 dimensional object may appear different according to the angle from which it is viewed, so the shape and length of a notional string may change too. In my overly simplistc way, it seems to me that particles and strings are the same thing. Both peceptions may be useful to a point, but bedrock theories based solely on either are likely to lead to dead ends, methinks.

Both Iran and powerful factions within Iraq consider they have a common enemy. Why is it surprising for them to cooperate? It would be illogical for them not to. With Saddam removed, one of Iraq's "natural" enemies disappeared. It has therefore identified a new enemy and customer base for its arms industry, two requirements it has learned from the U.S. industry. Now I do not wish Iran well in any of its activities, but it beggars belief that anyone can find them surprising. To defeat your enemy, you have to understand them and imagine yourself in their shoes. Is this perhaps a secret of military strategy taught only in staff college?

A working practical application, around for many years, has been in model aeroplane engines. The gas is stored using air in plastic bottles, or carbon dioxide from sparklet bulbs. One of the practical problems is for the engine or pressure valve to freeze. Such an engine appears to me to be half of a refrigeration cycle, afterall. Then there is the mechanical inefficiency of compressing your gas in the first place.

I think the very principle of rationing through taxation is wrong. It is, however, the easiest, cheapest and most bureaucratic profitable way. This is why it is the time-honoured kneejerk establishment response. During times of wartime emergency shortages, the even handed and democratic solution was through rationing, though this did impose a heavy administrative burden. Rationing through taxation imposes an inequitable burden on those least able to pay, while, regarding energy consumption in particular, giving the rich and profligate carte blanche to continue to burn up planetary resources at criminal speed. When I see legislation by the most energy consuming and wasteful countries that for example restricts "by choice" air travel and low mpg road transport, I will know that the problem is being taken seriously, but until then the political spin that keeps big business money flowing has my utter contempt.

Yes, Norm, they must be digitally driven. There is the catch, gotcha!

Would not, in a million years dare to presume to educate you, Norman. There is a mountain of net info on stepper motors, and I suggested tooth belt drive as non-slip alternative alternative to gear trains. I handcut my own gears. If they strip, it is because I have chosen the wrong material or wrong tooth size for the motor to load application, or deliberate overload when testing to destruction. If yours strip, it is poor design or jamming of the load (perforated drum), or even inadequate lubrication. I have to say I don't automatically trust plastic gears in sealed plastic boxes designed for toys, hobbyists or the low-cost DIY trade. They are made down to a price. Not designed to last the decades your pianos are expected to last.

I suppose you have already considered using a stepper motor and toothed belt drive, with digital speed control?

I'm done now, in that case.

And surely only two surfaces that do not deform under pressure from each other can have "pure" friction? If a small area of dense material presses on a softer, and creates a dent or well, surface friction is not the only counter-movement force to be considered? (This goes back to the original question?) A cartoon explanation? Do you mean like rubber sheets and bowling balls to explain gravity? There are more cartoon explanations in physics than there are episodes of Mickey Mouse. What is wrong with another one?

I spelled it wrong. It is now called stiction, and the term is commonly accepted as having been "invented" in the 90's in connection with hard disk drives, (breaking a "goo" bond between head and platter) though it was known to me long before that in connection with the idea I am floating. Don't know about limiting friction, seems more sensible to call it initial friction. How about the case of two surfaces having a sharp crystalline structure of equal topography, thus interlocking. Much force required to initiate movement, but once moving the surfaces will bounce over each other, no? Seems to me the greater the weight acting on the two surfaces, the greater initial mechanical unlocking force required, as distinct from ongoing movement friction. I am really asking out of curiousity, not giving an answer. I think there is more to friction than meets the eye.

I wonder if people confuse friction and "sticktion"? By sticktion I mean the initial force (not inertia) required to initiate movement between two surfaces, and friction the ongoing resistance to continued motion. Take two rough surfaces with equal roughness. At rest, the roughness will tend to interlock. Once moving (having overcome sticktion) the rough surfaces will not have time to interlock, the surfaces roughness tending to bounce over itself. In fact, with a given combination and type of roughness, there may be an optimum "unsticking" velocity. Sticktion is an engineering fact. Sometimes it is called rolling resistance as when a cartwheel requires a lot of effort to roll it out of a rut, but once moving it will tend to bounce over other ruts with no more real friction than if it were on a smooth road.

The radiology (x-ray) department in my local general hospital changed from crt to lcd some years ago. Cant be too bad if they are good enough for examining x-ray pictures and CAT scans. Nevertheless, for me there is/was some subjective vibrancy to the old crt screen that is now lost.

There is a lot of truth in that, I have noticed a gradual change in tone, too. The drop-off also seemed to coincide with the sanitization and censorship of the theology section. A clear case of one plus one plainly making two. To have to open up and scan through two forums is trebly tedious....one plus one now makes three. Or in other words, the bath is now clean and empty of water, but it is obvious to me where the missing baby went....down the plughole Contributions by resident experts has dropped off, and some seem to have gone missing completely. I wonder if the site administrators are aware, but dont want to admit their error or wash their private linen in public?

I took the question as symptomatic of a possible ditching of traditional party principles, and wondered just how far a party can shift before honesty demands a rename. Older, traditional democrats had a position on conscription possibly dating back to the flag burners of the Vietnam war era, but the trend towards concensus politics has betrayed them. New politics rquires new names.

Water filter manufacturers always talk up its effectiveness in conjunction with activated carbon, yet I have come across "independant" research that says its benefit is less clearcut, and some pathogens can become resistant. Here is one quote "In its ionic colloid state, silver is recognized as a germicide, or in some cases as a bacteriostatic. It is believed that silver is able to disable the particular enzyme that pathogenic bacteria and fungi use for oxygen metabolism, thus suffocating them. Other pathogens are destroyed by the electric charge on the silver particles, causing their internal protoplast to collapse, and still others are rendered unable to reproduce. Parasites are also killed while in their egg stage. " Silver contamination of potable water can be a health hazard, however. The literature seems confusing, there appears to be no definitive answer. Anyone else got an opinion?

In the U.K., when Blair decided to ditch all traditional Labour values in order to seize the middle ground for electoral purposes he renamed his party (new labour) and some jokers are toying with renaming Camerons party as "not the conservative party". Time for a dose of honesty in the U.S, perhaps. How about New Republican and Not The Democrats, then they can play musical chairs to get their bums on the few remaining chairs of the political middle ground.

I have often wondered about the psychological motivation behind tattooing and self-mutilation in general, having never been attracted to either, personally. In respect of prison tattoos, what little reading I have done on the subject indicates the inmates desire to conform with fellow convict peer pressure, while rebelling against mainstream society. The tattoo in this narrow case performs both functions. Unfortunately, as a leopard cannot change his spots, so an ex-con cannot change his tattoed skin. Rather like the mark of Cain, it is with him forever. I dont understand the present trend for more women to be tattooed, as traditionally it was associated with membership of the oldest profession. When I see a woman with tattooes, I always secretly wonder.....

Gib65: Thanks for the timely reminder of the original question. I am genuinely hard-put to think of a religion which is inherently bad to the point of being dangerous. True, it is not too difficult cherrypick out of context parts of many religions and thus subvert the original philosophy to selfish ends. This does not make the religion bad, just some extremist practitioners. I have many friends of different religions, none of them bad people, or I would not count them as friends. Weird, eccentric, puzzling, mildly crazy, incomprehensible perhaps but I love them all for the variety they bring to the party. None of those things are dangerously bad. I would go as far as to say that the statement "all religions are bad" shows a dangerously bad, extremist, and unbalanced attitude of mind. I know no-one personally who holds such views. There are however a few on these forums, and sometimes I wonder about their overall mental health.

Message from the lobster people of planet Zorg: We have no cerebral cortex, yet have conquered the problems of interstellar travel. Based on the information in this thread, we are modifying our mass-destruction weapons to cause you maximum pain and suffering when we invade in the name of lobstermanity. Signed, Golden Claws.

My position: Any religion is bad to the extent that it disagrees with your own. Works every time for me.

I saw an episode of "mythbusters" recently where a sheet of glass between a bodyheat source and an infra red detector rendered the detector ineffective. Are you sure that glass will transmit the energy spectrum you want? My oven door is glass, it remains relatively cool whatever the oven temperature.

Gathering evidence, publishing it, starting lawsuits, rousing the indignation of pet-lovers, that is the sort of campaign I could go along with. I dont see quite how such activities improve pet food, unless it is to enhance profits by seeing just how low in basic ingredient quality they can go without actually killing pets. All in all, not a justifiable activity for animal experimentation. It benefits no-one and nothing except the corporate bottom line. If the business were to fail in the face of stricter regulation, I would lose no sleep. (But then I am not a shareholder).

Have you considered brake fluid? boils from 150 upwards depending on grade, designated in Dot units, up to about 200c. Lower if contaminated with water. Dont know about colour.

[quote=In My Memory; IMM scampers off to find a life... Bye bye, have a nice long journey.....

Alens/aliens, well spotted. But in revenge I ask what is a poltican? Oh, I get it, polticans are called alens. Nice to imagine that an alien visitation would be non-political, but how would you stop the b******s sticking their noses in?