Slashdot Mirror

Actually it doesn't matter how well any one extractor works as they can easily be interconnected in series for multistage operation as described by Continuous Liquid-Liquid Extraction Via an Improved Centrifugal Contactor; you could even power the thing with a SEADOG pump/generator.

Qualitatively, what you'd expect from climate change is more precipitation (because there's more evaporation)

While I'm not a climatologist (I tend towards quantum physics), I'm not sure you can make that assertion. The formula for evaporation has myriad factors, including but not limited to heat. (The actual formula is W = [A + (B)(V)](Pw - Pa)/Hv). It was stated in a BBC Horizon documentary entitled Global Dimming that the more important factor was the amount of sunlight that hits the water, rather than temperature. In addition, the Horizon episode explains that there is both an observed decrease in evaporation and rainfall based on fine particulate matter in the atmosphere.

The exposed/not exposed distinction is based on entire grains, not single silver atoms. [...] grains are binary - exposed or unexposed, whereas a digital camera pixel has multiple levels

That is incorrect.

Quoting Chemistry of Photography, linked upthread:

When an exposed film is placed in a developer solution, the grains that contain silver nuclei are reduced much faster than those that do not. The more nuclei present in a given grain (i.e., the greater the exposure of that grain), the faster the reaction with developer and the darker the image at that site in the film. Factors such as temperature, concentration of the developer, pH, and the total number of nuclei in each grain determine the extent of development and the intensity of free silver (blackness) deposited in the film emulsion in a given time.

The process of development expands the initial free silver sites produced by incident photons, but is not normally allowed to proceed until the free silver consumes an entire singly-exposed grain (that would be phenomenally overdeveloping the film). Thus, the final amount of free silver in a grain is (not exactly linearly) proportional to the number of photons that have struck the grain, up to some limiting number of photons at which the entire grain will be saturated after development (such a grain is completely overexposed).

If you've ever heard of "pushing" a film, which is overdevelopment to compensate for underexposure, this works by allowing free silver regions in grains with a fewer number of photon strikes to grow larger (and the film to appear more "grainy" in the end). This would be impossible if the grains were only "on" or "off" as you claim. Overdevelopment wouldn't be able to activate unexposed grains anything but randomly, and the exposed grains would always be "on," no matter how long they were developed. You could make an argument that this is simply diffusion over the developer allowing for a larger number of active grains to be developed, but that would not account for the visible change in developed grain size.

Are you sure you understand silver-halide exposure? You're aware that individual grains are NOT either "exposed" or "unexposed". Instead, a certain number of silver nuclei in each crystal (or grain) will be present depending on how many photons the grain was exposed to. Developing helps amplify the effect, causing more of the grain to be "exposed", but by no means is it "all" or "none". Read about the chemistry of film here. In short, though, it's pretty darn analog.

In fluid processing industries, CSO is also a TLA for "car-sealed-open" (from old railroad car sealing technology; opposite is "car-sealed-closed", naturally) which refers to a valve which is locked in the open position, able to spew whatever content is in the pipes. Or tubes or trucks.

you could have just linked to http://www.cheresources.com/photochem.shtml or at least given a reference instead of just pasting like you got that off the top of your head =p

• one source
• other source
• search

*BZZT*

Sorry Fizzy, wrong answer. Show our wonderful contestent his consolation prize.

Well Bob, he has a choice today; they include

http://www.heatpipe.com/heatpipes.htm/
or
http://www.cheresources.com/htpipes.shtml/
or even *gasp*
http://www.benchtest.com/heat_pipe1.html

So you see, when being a dick on slashdot, make sure you've done your homework.

Just lots of them on a microscopic scale.

"Environmental Acceptability - Because fuel cells are so efficient, CO2 emissions are reduced for a given power output. The fuel cell is quiet, emitting only 60 decibels at 100 feet. Emissions of SOx and NOx are 0.003 and 0.0004 pounds/megawatt-hour respectively. Fuel cells can be designed as water self-sufficient. "

The complete reaction is explained there as well.

Not so great. Heat pipes work BETTER than copper of similar volume, by a substantial factor. That's why they are used instead of copper for the kinds of applications you are talking about.

Weird but true.

More info here and here.

"Water cooled" makes it sound like these Toshibas are the Porches of the laptop world (as opposed to the air cooled VWs). What we're probably talking about here are heat pipes based on water (it happens to have a really high heat of vaporization, the right viscosity, and a big change in contact angle- for the meniscus). They've been used in laptops for years, mostly to get heat up on that big fin called a screen that you flip up whenever you use one.

Check out: http://www.cheresources.com/htpipes.shtml
for more info on how these guys work. The key deal is that they don't require a pump to move the water, 'cause the heat does that work itself :^)

My experience is with the silicon micromachined versions of these. There are all sorts of problems they can develop (angle sensitivity, vapor lock...), but comercial versions work well, and have been around for decades, though they're not as small as you'ld like.

Currently folks at Stanford are working on electro-osmotic pumps for these exchangers to increase their efficiency/size ratio:
http://www.stanford.edu/group/micr oheat/hex.html
(use google if stanford fails to load like it did for me).

enjoy,
Kurth