Follow Slashdot stories on Twitter


Forgot your password?
Note: You can take 10% off all Slashdot Deals with coupon code "slashdot10off." ×

Comment Re:Might want to read the fine print... (Score 4, Interesting) 159

This is fine - they're not pretending those impacts don't happen, they are just not what they're studying. They are asking "What does the fallout do to people some distance from the accident?"

The exposure people get early in the accident and very close to the reactors depends hugely on the nature of the accident. At Chernobyl, there were many firefighters within meters of an exposed critical core, resulting in a large toll from acute radiation sickness. At Fukushima, the cores ceased to be critical seconds after the quake and tens of minutes before the tsunami, and radiation was only released days later, so there was no acute radiation sickness.

By contrast, the effect of the fallout is much less dependent on the nature of the accident, just on how much radioactive material was released*. It can sensibly be studied without specifying details of how the accident happened.

* There is some dependence: the relative quantity of short lived isotopes such as Iodine-131 in the fallout depends somewhat on how long the radioactive material was contained prior to release.

Comment Causation? (Score 5, Insightful) 87

The more niche your research topic, the longer the title has to be to describe it, and correspondingly the fewer people will be interested. Compare, for example, "A New Hierarchy of Phylogenetic Models Consistent with Heterogeneous Substitution Rates" with "The Origin of Chemical Elements". While one will be much more cited that the other, the reason isn't the title length.

Comment Re:We had one, it was called the Shuttle. (Score 4, Informative) 71

For the cost of one shuttle launch you could more than pay for SpaceX's entire development program so far. For two launches you could pay for their development so far plus the extra they'll need to finish the Dragon capsule and "man-rate" the system, and still have some money left over for a couple of launches (each of which can carry as many crew as the shuttle.)

(I'm taking the cost of a shuttle launch as about $1.5B. Lower values can be argued for, adjust the above as needed for your preferred cost.)

For a few more shuttle launches and a several year wait, Blue Origins would likely be able to field a man-rated rocket, if you want multiple space taxi companies to chose from. ULA could do it too, but that would probably cost you ten shuttle launches.

The shuttle was hideously expensive and needed to go.

Comment Re:Bullshit (Score 1) 100

It isn't clear to me whether they collect heat and use some heat engine, or whether they use a small area of high cost high efficiency high temperature photovoltaic cells. As I've complained elsewhere, the articles provide almost no detail. There is mention of cooling water, but either possibility could use that.

Comment Re:No details (Score 2) 100

You'd use differential GPS. Wikipedia says this has accuracy of 10cm in the best case. Whether that is good enough for this application I'm not sure. Given that affordability is a big part of their goal, if they were taking this approach they'd not attach a GPS to each mirror, but rather have two receivers that they used for a callibration stage and then wouldn't be needed again unless something shifted. You'd need to know orientation as well as location for the mirrors.

I doubt this is what they're doing, but who knows.

Comment No details (Score 4, Informative) 100

TFA is lacking in details about how this works, but if you follow the link you get to a Guardian article which is lacking in details, but links to the projects website which excessively uses gratuitous Javascript and is lacking in details.

They talk about "plonkability" - that the mirror structures can just be plonked on the ground and will 'just work'. This suggests to me that somewhere in their system is some intelligence or calibration which is able to notice where each mirror is relative to the target and adapt its pointing accordingly. Their photos show the target tower having two rectangular surfaces pointed towards the mirrors. I suspect the plane white surface is there to aid mirror pointing calibration in some way, but I don't know.

Comment A few more links (Score 2) 80

TFA was very short on detail, so I went looking for more. Unfortunately, there seems not to be much more out there - everyone is reporting on the same short-on-detail presentation. Here's a few which seemed to me to have something to add:
kitguru has more pictures
pcworld has pictures of actual silicon (not that it has any visible detail)
digitaltrends has some interesting commentary (last two paragraphs).

Comment TPP minus USA? (Score 4, Interesting) 258

Although it is hard to know because of the secrecy, it seems like there is a whole lot of stuff around 'intellectual property' and corporations getting to sue governments over policy changes which has been pushed hard by the USA and opposed not quite as hard by everyone else. So there is lots of stuff that objectionable to everyone but the USA. (Given that the USA parliaments haven't been allowed to see the TPP, possibly not even they want it. This could be stuff wanted only by the USA negotiators, not the country.)

What I want to see is USA kicked out of the TPP, then renegotiate to get rid of all the bad stuff USA pushed in. After that, the USA can negotiate for a late entry into the agreement. They can propose all this IP stuff, and the rest of us can consider whether we that badly want USA in the TPP.

That is pretty much a pipe dream, but more realistically: I'd like to see the governments of all participating countries go through all the provisions and state how strongly they are for or against them. If there are any bits that are liked only by negotiators, this would show them up.

It really worries me that this is secretly negotiated by people with almost no democratic oversight and will be presented as a monolithic take-it-or-leave-it with greater effective force than the laws of the participating nations.

Buying into the TPP is effectively accepting a huge lump of laws you had almost no say over and are almost impossible to modify in future.

Comment What is the evidence? (Score 1) 272

What is the basis for these new announcements? What do we know now that we didn't several days ago?

I can see an advance from "it looks very much like a 777 flaperon" to "we've inspected it closely and it absolutely is a 777 flaperon". Is that all that there is?

I'd expect such a significant piece to have a serial number and/or quality inspection stamps that could be traced back to a specific part installed into a known plane - but I've not heard anything about such a trace back.

Comment Re:Why does anyone care? (Score 2) 117

You can use high powered lasers in short pulses to compress and heat a fuel pellet to achieve fusion. A particular approach called fast ignition requires a petawatt pulse. Given that the laser is named LFEX for "Laser for Fast Ignition Experiments", it is a good bet this is what it is for.

(My expertise in this is limited to having had an inkling which Wikipedia article to look in for the answer. Further input from real experts is welcome.)

"More software projects have gone awry for lack of calendar time than for all other causes combined." -- Fred Brooks, Jr., _The Mythical Man Month_