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Comment This has been known for years (Score 1) 380

The idea that Gaeten Dugas was "patient zero" was thoroughly debunked soon after it initially circulated. The idea of "patient zero" sprang up because of a paper in the early 1980s ( which implicated Dugas as patient zero. The paper tried to track down AIDS patients' sexual partners, and it included a graph of who had slept with whom. The graph had Gaeten Dugas at the middle of it, connected to all the other AIDS patients through a series of sexual links. Dugas was labelled as node "0", and the others were labelled "1" or "2", etc, depending on how many degrees they were removed from Dugas. (

The paper was mistaken. Although those early AIDS patients were all sexually connected to Dugas by at most a few degrees of separation, that does not imply that they acquired the infection from him. It's known now that HIV has a latency period of more than 8 years in young men before overt illness appears. Most of the early AIDS patients reviewed in that paper had directly or indirectly slept with Dugas only 10.5 months before symptoms started appearing in them, which implies that they had not been infected by him. Those AIDS patients who started getting sick in 1982 probably acquired the infection in the early 1970s, long before the sexual encounters with Dugas outlined in that paper. This has been known for more than 20 years.

The problems with the paper are: 1) a few gay men are highly sexually active and sleep with 100+ partners per year; 2) it takes many years for overt illness to appear; and 3) HIV is not highly infectious. As a result, those early AIDS patients may have had dozens of exposures to the virus over the years before encountering Dugas. Within the gay community there is a smallish subset who are hyper sexually active, and they are all sexually connected to each other, with only a few degrees of separation, at least within a particular city. At that point you're just playing the Kevin Bacon game; you can connect anyone to anyone else, and draw a graph however you like.

Comment Commodore (Score 1) 620

I had a college professor who strongly resisted getting a new computer. He had a commodore PET with 8 KB of ram. He would type his handouts into the PET, but it could only hold about 3 pages of text before running out of RAM, so his handouts would end abruptly (sometimes mid sentence) because he had run out of memory while typing. On the PET, you could create longer documents by establishing a new file when you ran out of RAM, but he usually didn't bother. When he printed the document, he only had an 8 pin printer, so it couldn't print the letters 'g' or 'p' properly. It was hard to read because he would use a mimeograph machine to produce copies after printing,

Comment SF Bay Area (Score 5, Interesting) 940

I've lived in the San Francisco area almost my entire life. In the SF area, the vicious cycle works like this:

1. Some progressive people live in an urban area, and they decide that they cannot stand urban areas, urban development, or tall buildings. They protest any construction, relentlessly, for decades. Any time anybody tries to build anything, the result is protests, lawsuits, and so on. This has been going on since about 1980. As a result, there was almost no housing development in this area for 3 decades despite steadily increasing population and prices. Granted, some construction started about 4 years ago, but it's WAY too late and not nearly enough. (Apparently, the same thing is happening in New York. The most preposterous example of this is people who've moved to Manhattan and decided that they can't stand tall buildings in Manhattan because tall buildings cast shadows).

2. When rents increase, those people who prevented housing construction decide to blame Google, blame Yahoo, and so on, not blame themselves. Remarkably, they start protesting the construction of housing again. I live in Oakland (just east of SF) and there have been protests against building new housing on EMPTY LOTS, during a housing shortage of critical proportions. People show up and start chanting "we want development without displacement!", as if displacement was caused by too much housing.

Recently I walked around the area south of market st, and saw that typical rents for a 1 bedroom are $6000-$7000 per month, and it's not a luxury area at all. Oakland is getting bad too, but not that bad yet. As a result, the progressive faction has now erupted into a fit of hysterical rage and they vomit on buses which transport tech workers to work.

Comment Re:Wikipedia is sometimes wrong (Score 1) 165

No, it works with non-controversial subjects.

Unfortunately, it also works with controversial subjects if the article is obscure enough.

I recently came across a page about a fringe crackpot group which included highly inflated membership estimates (in the millions of members, rather than a more accurate estimate of about 300 members). Since the group was very obscure, the incorrect claim had persisted for years. The only people monitoring the page appeared to be group members.

Comment Re:Wikipedia is sometimes wrong (Score 1) 165

Fortunately, the tools for automatic jerk identification are improving.

If that were true, you wouldn't be able to post on slashdot.

As one of the people who spends time cleaning up stuff like that, it's seriously annoying.

It was a legitimate experiment to an extremely obscure article, and it had no serious negative consequences.

Promoters of wikipedia frequently claim that the source is highly accurate because inaccuracies are rapidly corrected. If they make claims like that, it's legitimate to test whether the claims are true.

Comment Wikipedia is sometimes wrong (Score 4, Informative) 165

As an experiment, I added a spurious and incorrect fact to an obscure wikipedia article, complete with a reference to a document which did not support the claim. It took years before my edit was noticed and reversed.

This only works with obscure articles. The more obscure the article, the less it's checked. If you try inserting something spurious into the page on Obama it will be reversed in about 5 minutes.

Comment Re:Still pretty affordable (Score 1) 393

I don't think that's right. I've known a couple of EV owners in CA who claim that the electricity costs are less than half what gasoline costs, per mile. The Chevy Volt uses 10 KwH of battery capacity to travel approximately 40 miles. That's 0.25 KwH/mi, which is $0.0375 per mile with electricity at $0.15 per KwH (in CA). Gasoline is about $4 gal and can take a car about 35 miles, which is $0.1142 per mile, which is ~3x as expensive as the EV.

Comment Re:Everything old is new again (Score 1) 491

I didn't know that. It's strange that SF owns its own power plant for city services.

I suppose I can act like an economist here, and say that electricity for public services in SF still isn't really free. SF could sell that electricity for 6 cents per KwH, so there's forgone income which should count as a cost.

Comment Re:Container ships (Score 1) 491

I can see why we'd want to stick with bunker fuel for ships, since only ship engines can burn that kind of fuel. It takes huge engines to burn that kind of fuel. As you pointed out, no. 6 bunker fuel isn't liquid at room temperature so it's necessary to pipe the exhaust past the fuel tank in order to melt the fuel, so the fuel will flow into the engine.

Without ships, bunker fuel would kind of be a useless waste, since no other engines can use it. I suppose it could be burned for heat or electricity, but oil is an awfully expensive way doing those things.

I'm more familiar with the economic aspects of the ocean shipping industry, than the engineering side. I wonder if it would be possible to filter out some of the crap that comes out of the smokestack. That way ships could continue to use bunker fuel without harming the health of people around. Something akin to a catalytic converter on cars.

Comment Re:Everything old is new again (Score 5, Interesting) 491

San Francisco has had a fairly extensive trolleybus network since the 1930s. Although only 15 bus lines are trolleybuses, those are the most crowded bus lines, so a significant fraction of bus traffic there is electrified.

It appears that diesel buses cost $450,000, and battery-electric buses cost $825,000, and trolleybuses cost $1m each. Trolleybuses last at least twice as long as diesel buses. The overhead wires cost $2 million per mile and last almost indefinitely, it appears, because I have never seen maintenance being performed on any of them, in contrast to roads and stoplights which are being repaired constantly, and buses which are being replaced often enough.

San Francisco has 300 trolleybuses for 15 lines, and each line is about 6 miles long. Thus the overhead wires cost $180m, the buses cost $300m, and the electricity costs $48m over 24 years. It appears that equivalent diesel buses would cost $270m and use $330m in fuel over 24 years, servicing the same routes (just using the numbers I read from an article and doing the calculation manually). It would appear that trolleybuses cost ~$528m for those routes and diesel buses would cost ~$600m. However, that's not taking into account financing costs etc, which would probably make the trolleybuses more expensive than diesel ones since the upfront cost is higher. Also, this is for routes in San Francisco which are only 6 miles long; the economics may change for suburban routes.

That said, it doesn't seem like the costs are very different whether we choose trolleybuses, diesel buses, or battery-electric buses. It may be slightly more expensive to go electric, but not much.

Comment Re:Container ships (Score 5, Informative) 491

The 15-30 largest container ships in the world (depending on who's estimates you're using) produce more pollution than all the cars combined.

The largest container ships have huge particulate emissions, but that's because there's no regulation on particulate emissions according to international law. It would be difficult to change that, because regulating ships requires an international agreement. That said, it should be done.

However, ships already have extremely low CO2 emissions per ton-mile. They are already extremely fuel-efficient. The largest ships have 1/15th the fuel usage and CO2 emissions per ton-mile as a tractor-trailer truck, and massively better than your car. If you drive one mile to the store to buy an article of clothing, you have emitted vastly more CO2 than was emitted by shipping it halfway around the globe by containership.

You want to reduce emissions? Pay for it to be grown locally instead of on the other side of the globe.

That will have almost no effect on your CO2 emissions.

Comment Re:Law of Large Numbers (Score 1) 442

You missed the point of the post. Lovins was talking about unscheduled downtime like the wind not blowing, or a reactor scramming because of a tremor. He was claiming that renewables were similar to baseload power plants in that they both have unscheduled downtime. I was responding to that.

Of course there is also scheduled maintenance, but that's not what Lovins was talking about. That has no relevance to the discussion of whether storage would be required for renewables. If Lovins was talking about scheduled downtime then his point was even weaker.

Comment Law of Large Numbers (Score 3, Interesting) 442

I think the biggest mistake of the video, is when Lovins says that renewables are no different from baseload power plants, because baseload plants are down some fraction of the time also. He claims that power companies already compensate for downtime of baseload power plants by just having a few extra power plants. He claims that the same thing could be done with renewables.

That's just all wrong, in my opinion. It's a statistical error. Although baseload power plants are down 10-20% of the time, they are down at random. The downtime of any one plant is not correlated with the downtime of any other. As a result, if you have enough plants, then 10-20% of power generation is offline at any given time, as a result of the law of large numbers. That can be compensated for by building a few extra power plants.

With renewables, their downtime is not random. Their downtime is correlated with that of the other plants. For example, when the sun goes down, all solar panels stop working at the same time in a geographic region. Also, when the wind stops blowing (which can happen over a wide area), all windmills in that region will stop working at the same time. This is a much bigger problem than randomly distributed downtime.

If solar panels had randomly distributed downtime, and were as likely to generate power during winter nights as during summer days, then no storage would be required. We could just build more solar panels. This is because the randomly distributed periods of downtime of the solar panels would "cancel out" each other. However, it does not help to build more solar panels for the night time.

That is why renewables require storage.

Comment Re:Ammonia fuel (Score 1) 117

Even if it only made 0.0001% nitric oxide and some kind of catalytic converter caught 95% of that, it would still destroy the environment faster than fossil fuels.

I doubt that. Burning a gallon of gasoline in an internal combustion engine produces about 1.5 grams of NOx, which is more than would be emitted by 0.0001% from ammonia combustion.

And that's if none of the ammonia ever escaped from vehicles, let alone the industrial production and transport.

Ammonia is a basic building block of life and is already produced in huge quantities by bacteria in the soil. Furthermore, it's produced in massive quantities by industry, at a rate of 150 million tonnes per year worldwide. That's more than 20kg per person, per year, worldwide, which is more than any other chemical. No attempt is made to confine that ammonia or prevent it from leaking into the environment. Quite the contrary, that massive quantity of ammonia is injected directly into the soil as fertilizer, or evaporates from window cleaner. The amount we are leaking into the environment right now, is vastly greater than the amount which would leak from the occasional defective fuel tank.

If ammonia is causing some dire environmental effect, worse than global warming, then I've yet to hear about it. I'm not saying you're wrong, but you'd have to provide some evidence for your assertion.

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