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Comment: Re:Cheapest Plan (Score 2) 273

by Mendenhall (#46444073) Attached to: WSJ: Americans' Phone Bills Are Going Up

You missed the good part of the T-Mobile PAYGO plan: once you have paid the $100 once (or accumulated it via smaller payments), all your future added minutes last a year. So if you haven't used $100, you can top off with $50, or even $10, at the end of the first year, and it roll the leftover minutes forward to the next year and add the new minutes. If you buy fewer minutes, you are paying a bit higher price per minute, but you never lose the old minutes as long as you top off. This is why the original purchase of $100 is worth it, since you get the best rate ($0.10/minute).

Also, T-Mobile has great deals on refurb phones often. I bought a Dart (not a great phone, but it works), For $90, which came with a $50 card for minutes. Thus, a useable Android phone for $40. It does support WiFi data tethering, so I can pay the $2 or $3 rate for a day when I need data, and have that for my other devices, too.

Comment: Re:Ridiculous (Score 2) 521

by Mendenhall (#45799391) Attached to: Ford Rolls the Dice With Breakthrough F-150 Aluminum Pickup Truck

There are a number of issues with the calculations here.

First, you estimate that it takes about 1 gallon of gasoline equivalent per pound of aluminum (1800 gallons for 2000 pounds). This then seems to say that the energy cost for aluminum should hover around $3.00/pound (the price of the gasoline), or maybe half that since electricity is cheaper. Maybe $1.50/pound for the energy. It currently sells for $0.75/pound on the spot market, so the energy input is somehow wrong.

Also, if a truck gets 20 miles/gallon, it burns 5000 gallons in 100k miles. If it gets 25 MPG, it burns 4000 gallons in 100k miles, so the difference seems to be about a 1000 gallon improvement in consumption, not a 200 gallon improvement. If your original arithmetic is sound, you would still end up in the hole if you burned the truck at the end, but aluminum is highly recyclable with only a tiny fraction of the original energy, so in the long run I think it comes out ahead even if the original numbers are right. However, I think that with some mis-estimate of the original energy budget, it might come out ahead even on the first pass, without considering recycling.

Comment: Re:Blech (Score 2, Interesting) 214

by Mendenhall (#45177101) Attached to: US Should Cancel Plutonium Plant, Say Scientists

The Union of Concerned Scientists includes some scientists, but is an anti-nuclear political organization. This headline is like saying "Teenagers have unhealthy fantasies playing D&D, say mothers" amd omitting from the headline that "mothers" really refers to "Mothers Against Dungeons and Dragons".

This is not even close to correct about the policies of UCS. See:

http://www.ucsusa.org/nuclear_power/
and
http://www.ucsusa.org/nuclear_power/nuclear-power-and-our-energy-choices/nuclear-power-and-global-warming/house-testimony-on-nuclear.html

They are very strongly looking at nuclear safety issues, but specifically are neither pro-or-con on nuclear power itself. The organization does a great deal of research into all matters related to energy and safety and sustainability issues. They are well aware of the carbon-free nature of nuclear power, and that if it would be managed safely, it could be highly beneficial.

Comment: Re:Different thing altogether... (Score 1) 135

by Mendenhall (#44902519) Attached to: iOS 7 Lock Screen Bug Leaves Certain Apps Vulnerable For Access

I know they are different things, but it was the camera access that got my attention. Disabling Control Panel access, I think, as I mentioned in the original post, avoids the issue. As far as I can tell, there is no way to get to anything on my iPad without unlocking.

The ad hominem about my lacking imagination and/or sense was not needed or polite.

Comment: Easily avoided (Score 1, Informative) 135

by Mendenhall (#44902081) Attached to: iOS 7 Lock Screen Bug Leaves Certain Apps Vulnerable For Access

As soon as I did the iOS7 update, I noticed that you could access the camera from the lock screen, and I didn't want someone taking inappropriate pictures on my iPad if they stole it. There is an option in the settings which controls what features are available from the lock screen. If you turn off the Control Panel access from the lock screen, and everything else, this goes away.

So, it's annoying but not fatal as a security issue. I can't imagine anyone wanting to have the device open for the camera when it is locked. I do wish the options were flexible enough that one could still adjust audio settings with it locked.

Comment: Re:The trouble is Apple bans programming apps (Score 1) 340

by Mendenhall (#44723451) Attached to: For Education, Why TI-83 > iPad

Any app that provides programmability is not allowed....

Well, that would be true if you couldn't get Python 2.7 for iOS. There are, in fact, two different full python implementations of python on the App store. I have used it to run my vxi-11 stack to talk to oscilloscopes and other data acquisition stuff. Works fine. The only annoyance is that you have to cut & paste large programs from email (for now) to get them in. You can edit code in the editor, though, so small programs can be done right in place.

Comment: Light, intermittent prepaid -- t-mobile, is good (Score 1) 286

by Mendenhall (#37030926) Attached to: Verizon Cracks Down On Jailbreak Tethering

I am a t-mobile prepaid customer, with one of their LG Android Optimus-T handsets, which I got for $130 refurb.
I can get legal tethering from them by setting up the phone as a mobile hotspot for $1.50 a day. If
you use it every day, it is quite expensive, but if you just use it a few days a month for travel or
whatever, it is great. They give you 30 MB of very high speed (I think I have seen 1 MB/sec peaks),
and unlimited 2G for the rest of the day. If you are just checking email, or doing bandwidth-restricted
video chat back home for a while, it is plenty.

I juts got back from a conference trip, where the hotel charged $10/day for internet and you
couldn't even get it in the main conference area, and they didn't even have free internet in the
lobby. I spent my $1.50/day, and was able to edit code via ssh, talk to my wife via video chat
for a while, and look at the web. I had to make sure I did the video chat at the beginning of the
session, while I still was under the 30 MB throttling limit.

Comment: Re:Union of Concerned Scientists (Score 2, Informative) 277

by Mendenhall (#33945648) Attached to: Scientists Fight Back In Canada

You do know that the Union of Concerned Scientists has been around since 1969, not since Bush Jr., don't you? Did you read their history on their web site?

They (we, in this case) certainly have been more vocal during the most egregiously anti-scientific administrations, but Bush Jr. wasn't the first.

Comment: Excellent book about Nazi uranium project (Score 3, Informative) 205

by Mendenhall (#31243358) Attached to: Lost Nazi Uranium Found In a Dutch Scrapyard

There is a truly excellent book, "Hitler's Uranium Club" which documents what the Germans themselves said about their efforts. It is edited by Jeremy Bernstein. It is a collection of transcriptions of conversations among the leading German scientists (Heisenberg, Laue, etc., not all of whom were actually doing nuclear physics), who were captured lat in the war and transferred to Farm Hall in England. They were recorded secretly, so what is said is very candid.

Anyone interested in this history should definitely read the book. The conversations run the gamut from very technical, to various fights over social issues.

 

Image

PhD Candidate Talks About the Physics of Space Battles 361

Posted by samzenpus
from the load-photon-torpedoes dept.
darthvader100 writes "Gizmodo has run an article with some predictions on what future space battles will be like. The author brings up several theories on propulsion (and orbits), weapons (explosives, kinetic and laser), and design. Sounds like the ideal shape for spaceships will be spherical, like the one in the Hitchhiker's Guide movie."

Comment: Re:This is NOT a battery, it's a RTG (Score 1) 444

by Mendenhall (#29694591) Attached to: Penny-Sized Nuclear Batteries Developed

If I could get my hands on say an ounce of Pu 238 I could build a RTG that would power my home, all my vehicles, and enable me to quit my job and live of the check my local electricity provider would have to pay me for the excess power I would generate. It would generate full power for ~ 87 years and not only wold I be using the greenest power available I would be providing a community service of disposing of a radioactive material.

OK, you must have a very efficient house. The specific heat output of Pu238 is about 0.5 Watts/gram, so an ounce puts out about 14 Watts. Given 10% RTG efficiency (which is much better than normal), I give you about 1.5 watts from this. Can you run your house on that?

Businesses

The "Dangers" of Free 242

Posted by ScuttleMonkey
from the poor-execution-kills-even-good-business-models dept.
With today's Free Summit broaching the subject of the "dangers" of free, TechDirt has an interesting perusal of why free often can't work without a good business model and why it often gets such a bad reputation. "I tend to wonder if this is really a case of free gone wrong or free done wrong. First, I'm always a bit skeptical of 'free' business models that rely on a 'free' scarcity (such as physical newspapers). While it can work in some cases, it's much more difficult. You're not leveraging an infinite good -- you're putting yourself in a big hole that you have to be able to climb out of. Second, in some ways the model that was set up was a static one where everyone focused on the 'free' part, and no one looked at leapfrogging the others by providing additional value where money could be made. The trick with free is you need to leverage the free part to increase the value of something that is scarce and that you control, which is not easily copied. [...] Still, it's an important point that bears repeating. Free, by itself, is meaningless. Free, with a bad business model, isn't helpful either. The real trick is figuring out how to properly combine free with a good business model, and then you can succeed."

Top Ten Things Overheard At The ANSI C Draft Committee Meetings: (1) Gee, I wish we hadn't backed down on 'noalias'.

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