Slashdot Mirror


User: drerwk

drerwk's activity in the archive.

Stories
0
Comments
595
First seen
Last seen
Profile
(view on slashdot.org)

Comments · 595

  1. MTW - GRAVITATION on Ask Slashdot: Math Curriculum To Understand General Relativity? · · Score: 2
    This was the book on General Relativity when I was at Caltech.
    From the preface:

    This is a textbook on gravitation physics (Einstein's "general relativity" or "geometrodynamics"). It supplies two tracks through the subject. The first track is focused on the key physical ideas. It assumes, as a mathematical prerequisite, only vector analysis and simple partial-differential equations.

    It is a really fun book to read at the first track level; especially if you are not on the hook for the homework.

  2. Re:Ironic on Book Review: Ghost In the Wires · · Score: 1

    I have to wonder what the masses did the first guy who brought home fire.

    I'd have to guess that they bound him to a rock and had a giant eagle eat his liver.

    The gods did that, not the masses.

  3. Re:Kind of unsafe? on Company Wants You to Visit Near-Space In Their "Bloon" · · Score: 1

    http://www.designboom.com/weblog/images/images_2/2011/jenny/bloon/bloon05.jpg
    Looks like a pressure capsule.
    Jenny is a lung buster. ( apologies to the Ramones )

  4. Try the Atomic Web browser on Browser Wars Redux: This Time It's the Apps · · Score: 1

    Try the Atomic Web browser which lets you easily set the agent response as Mobile Safari, Mobile Safari - iPhone, Mobile Safari - iPad, Safari Desktop, Wap Device, Firefox 3, IE 6, IE 7, IE 8.
    I only wish I could specify the setting per web site.

  5. Re:Decent idea. on Massive Solar Tower Planned For Arizona · · Score: 1

    It's called a thermal. Arizona has some of the best soaring in the world because of them. I've ridden them up to 14k ft regularly; up to 18k once. Sure, it is different from what would happen if the plant was not there, but not in terms of total energy deposited by the sun on that area.

  6. Re:Actually they didn't on IBM Did Not Invent the Personal Computer · · Score: 1

    I used to hang out at The Personal Computer Place in Mesa, AZ. I assembled a few SWTP 6800 systems, an IMSAI, and I think an ALTAIR for the owner who sold both kits and the assembled products. That was 5th grade, so must have been 1977. I recall him getting his first Apple II, it was awesome.

  7. McAfee Gap Shaft on McAfee CSO Issues Warning On the 'New Cold War' · · Score: 2

    take it as you will

  8. Re:repeatability on Fermi Lab's New Particle Discovery in Question · · Score: 1

    Pretty sure D0 and CDF are each using their own data; different detectors means different data. Maybe the same beam runs though which would give same collision energies.

  9. Re:Nonsense on Could Apple Kill Off Mac OS X? · · Score: 1

    Are you really saying a $300 PC compares to a $2400 Mac Pro?

  10. Re:Nonsense on Could Apple Kill Off Mac OS X? · · Score: 1

    Less than the $3,000 I spent on my Apple II+. Less than the $6,000 I spent on my IIci. About the same as the Powerbook I bought. Each one was well worth the ROI.

  11. Re:Rectification is the hard part on Capturing Solar Power With Antennae · · Score: 1

    Short answer is impedance mismatch. 60Hz has a wavelength of about 3000 miles, and you need a wire about that long to couple and cause radiative dissipation. When you get to THz, pretty much anything bigger than a gnat will now be an antenna. And there are other issue with conductivity being a function of frequency and so on.

  12. Re:Most important point not in summary on Capturing Solar Power With Antennae · · Score: 1
    The P fails to notice that they are not yet able to rectify the current, and hence can not yet get power out, and so the 90% number is only for antenna coupling, not conversion to DC current.

    More extensive research needs to be performed on energy conversion methods to derive overall system electricity generation efficiency.

    It is like saying current solar cells are 90% efficient because 90% of photons are absorbed; it says nothing about the quantum efficiency of conversion. I am willing to bet that the QM Efficiency of the necessary rectifier will be the big loss; though it may only be 50%.

  13. Re:Fine for gas or diesel, on Electromagnetic Automobile Suspension Demonstrated · · Score: 1

    I am not sure about the brakes using only a tablespoon. If I recall on my ID-19 and DS, there is an anti-dive mechanism used during braking and I think it worked by putting more fluid into the front suspension, which not directly due to braking would still cycle the pump.

  14. 23andme does not sequence your DNA on Graphs Show Costs of DNA Sequencing Falling Fast · · Score: 2
    As some ACs have pointed out in response to a few of your posts on this thread, 23andme does not sequence your DNA.
    https://www.23andme.com/you/faqwin/sequencing/
    my emphasis:

    What is the difference between genotyping and sequencing?

    Though you may hear both terms in reference to obtaining information about DNA, genotyping and sequencing refer to slightly different things.

    Genotyping is the process of determining which genetic variants an individual possesses. Genotyping can be performed through a variety of different methods, depending on the variants of interest and resources available. At 23andMe, we look at SNPs, and a good way of looking at many SNPs in a single individual is a recently developed technology called a “DNA chip.”

    Sequencing is a method used to determine the exact sequence of a certain length of DNA. Depending on the location, a given stretch may include some DNA that varies between individuals, like SNPs, in addition to regions that are constant. So sequencing is one way to genotype someone, but not the only way.

    You might wonder, then, why we don't just sequence everyone's entire genome, and find every single genetic variant they possess. Unfortunately, sequencing technology has not yet progressed to the point where it is feasible to sequence an entire genome quickly and cheaply. It took the Human Genome Project over 10 years' work by multiple labs to sequence the three billion base pair genomes of just a few individuals. For now, genotyping technologies such as those used by 23andMe provide an efficient and cost-effective way of obtaining more than enough genetic information for scientists—and you—to study. Copyright © 2007-2011 23andMe, Inc. All rights reserved.

    To be sure you have gained interesting information for your $200, but you have neither your sequence, nor a complete list of differences from a reference human sequence, which of course if you did would give you your sequence.
    23andme only gives you a list of many SNPs.

  15. Re:Interesting idea, horrible article on For California, an Earthquake Early Warning System Is Up and Running · · Score: 5, Insightful

    Without reading the article, it is a computer which then calls the fire department garage doors and they open. The FD will not collapse on the Engines but the door may jam, or not work for lack of electricity. Also some elevators may stop and open at the nearest floor. hospital generators may start. That sort of thing. I am not expecting a text that say duck. I was in Santa Cruz eating dinner for the '89 and it was terrifying. Even though the fire engines got out, the roads were choked and they could not get anywhere. After about 15 minutes, I could count about 6 fires in the distance. I had even heard it might give warning in surgery to pull out instruments and cover the patient to keep dust out.

  16. Re:Leave Steve Jobs Alone on Steve Jobs Health Worries Escalate · · Score: 1

    It is not a secret that he is private about his health^H^H^H^H^H non-apple life, nor am I aware of an instance where he has given false info regarding his health. So, any investor that cares to factor lack of knowledge about Job's health and the resultant uncertainty can do so. No one forces anyone to invest in APPL. Are you really saying the Enquirer is doing this to inform investors? I think it is to sell papers with any vulgar info that works for them.

  17. Re:Frequencies? on 4G Broadband May Jam GPS · · Score: 2

    Look up FourierTransform. A signal of finite length; say a dot or dash, can not be represented by a single frequency. The only way to have a carrier at a single frequency is for that signal to exit over all time. Certainly you can get a narrow band of carrier if you have a longing signal, but as hinted elsewhere, in order to convey an increasing amount of information you have to make your dot and dashes ever shorter, which in turn increases your bandwith both of information and of carrier.

  18. Re:So... on Bill Gates Says Anti-Vaccine Effort Kills Children · · Score: 1

    http://en.wikipedia.org/wiki/Herd_immunity
    Protects un-vaccinated, and those for whom the vaccine did not provide 100% protection.

  19. Re:Class Difference on The Rise and Rise of the Cognitive Elite · · Score: 1

    Not anyone can get a degree from MIT or Caltech, and in both cases if you get in they give really good financial aide. I assume that is true for some number of other similar institutions. I frequently interview MIT grads, and the question is not if they are smart, but can they work in a team.

  20. Re:Class Difference on The Rise and Rise of the Cognitive Elite · · Score: 4, Insightful

    I think one of the key traits the degree shows is the ability to work hard enough and long enough to earn one. A coach of mine told me a man with a plan will beat a genius 90% of the time which is similar to Edison's quote of 99% perspiration. Being intelligent is not enough if you can not finish the work.

  21. Re:Apple II+ disks from 1982. on What's the Oldest File You Can Restore? · · Score: 1

    The IIc was a great machine, 128K, nice color. It was my main machine at Infocom. But my II+ has no RS232, and I did not want to buy an old IIc.

  22. Apple II+ disks from 1982. on What's the Oldest File You Can Restore? · · Score: 2

    I connected the printer out to a linux parallel in, wrote a Linux reader and did a PR#6 on the apple. I've heard of people using the audio out in a similar manner. I'm amazed that the Apple II+ disks seem to be in readable condition.

  23. Re:Summary is wrong - should be 240km/h. on Navy Uses Railgun To Launch Fighter Jet · · Score: 1

    I might buy 6g as possible for a pilot on launch. But I am near certain that 130 kts would fly any carrier based loaded fighter.

  24. Summary is wrong - should be 240km/h. on Navy Uses Railgun To Launch Fighter Jet · · Score: 1

    Good. Now, noticing that 6.3g is too much for the pilot, someone should figure out that the article has 240mph, when it should say 240km/h. So, it is closer to 3g. This pdf has quite a bit more info. http://www.edn.com/contents/images/207108.pdf

  25. iTunes LP was made available on iBook Store Features Leave Indie Publishers Behind · · Score: 3, Informative

    http://www.apple.com/itunes/lp-and-extras/
    I would expect the same in a few months for any iBooks thing.