Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment Re:Unfortunately no and I have a reason (Score 4, Informative) 244

Reading those books requires high degree of mathematical sophistication, particularly, knowledge of complex analysis, which I lack.

They're just algorithms textbooks. They're hard to read because of when they were written, and the accompanying style. More like pseudo-assembly than high-level pseudo-code.

But, hey, if you want to optimize your search algorithm that uses tape as storage, to take advantage of the new-fangled tape drives that can write backwards as well as forwards, it's the book for you! (Yes, that was really a thing, and an algorithm you'll find in Volume 3: Sorting and Searching.)

Personally, I don't think he does a great job explaining algorithms. I once needed to look up O(n) median for something, tried to understand it from Knuth, gave up on the cryptic text, and understood it right away from CLR (now CLRS). It is an exhaustive catalog, but it's not a great learning tool.

Comment Re:Visual Studio C++ equivalent? (Score 3, Informative) 98

I develop C++ applications mainly for Linux. I use Visual C++ and Xcode (I got accustomed to it after some time) to develop, then I log on Linux to "port" the code with vi, GCC, etc, and add Linux specific features.

Is there a decent GUI for developing on Linux now?

You can use VS on a Windows machine to build/debug on Linux now. You can also run a light version, "VS Code," natively on Linux - it's free and open source, but I don't know how full-featured it is.

Comment Re:No life, cannot evolve there (Score 1) 66

The paper under discussion is a theoretical study not an observational one. They don't claim to have fund - or even looked for - phosphorus. But since we know that phosphorus is produced in the "oxygen burning" phase of large stars (I don't think the Sun will ever get there), and is present in planets (direct analysis on Earth, Moon, Mars and less directly in some asteroids ; spectroscopy as phosphine in the atmospheres of Jupiter and Saturn, e.g. http://www.sciencedirect.com/s...) and in molecular clouds (spectroscopy again, https://www.ncbi.nlm.nih.gov/p...), the there is no reason to not expect to find phosphorus in our putative brown dwarf. More - from the abundance in molecular clouds, we can make reasonable estimates of how much there is.

Though there are a variety of non-volatile phosphorus species (e.g. metal phosphides), the presence of phosphorus in the upper atmosphere of Solar System gas giants sufficiently indicates to me that in hydrogen-helium dominated systems, appreciable amounts of phosphorus would be available. Phosphorus might be a limiting nutrient in such an environment, but it is also in some terrestrial environments (that's why farmers apply "NPK" - nitrogen, phosphorus, potassium - fertilizer by the tonne).

the hoopla over supposed replacement of it with arsenic in a certain bacteria has proven to be false.

That was indeed a false result.

Replace phosphorus with arsenic and you get dead organism.

That way of building life without phosphorus doesn't work. That is not a proof that no way of building life without phosphorus works. (But you'd probably have to do a lot more than just a straight swap of P for As.)

Comment Re:Oceans have life at different layers (Score 1) 66

Oceans have life at different layers, so why not gaseous atmospheres of varying densities?

Except for very temporary, small-scale local "inversions", the density of atmospheres increases as you descend into them. Same physics from 100-odd Kelvin (Jupiter cloud tops) to many thousands of K (O-stars).

OTOH, we still can't spontaneously make life in the lab YET

FTFY

so we don't know all its secrets, and perhaps in reality, our knowledge is very limited (you don't know what you don't know).

We don't know what we don't know, but we do know what we do know in the laboratory - about how to construct enzymes and structures abiotically, in the beaker - and we do know what basal ("primitive") Bacteria and Archaea do in their metabolisms, and the gap is closing fast.

Speaking as a geologist with billion-year old fossils which I collected with my own hands, I'm more confident of seeing the biochemical gap closed than I am of a strong answer to the question "did life evolve a billion, or a half-billion, or a quarter-billion years after formation of the Earth?"

Comment Re:Heard this before. (Score 1) 66

The Integral Trees is a free-falling environment, but it's in the accretion disc of a neutron star, not the atmosphere of a brown dwarf.

It's an interesting exercise in working out an environment, but TBH, far from my favourite bit of Niven. I can barely remember the plot(s), nor even if I've actually read more than a couple of the books.

Comment Re:Mission Impossible 6 (Score 1) 229

The device will include an astable oscillator (driven off the power lines), probably operating in the audio range (because components are cheap. So 1 second after you plug it in, your oscillator has done a couple of thousand cycles and is driving current into the capacitors at the highest voltage it can. How much charge the capacitors can handle will determine how much time it takes to fully charge, but you wouldn't need to plug/ unplug it multiple times.

(I had to repair a 1950s Geiger counter once, which needed a 120V DC battery which fitted into the footprint of a square "lantern battery" - about 65mm square by 120mm tall. These batteries haven't been made since the 1970s, so I had to build a standard rechargeable battery and DC-DC step-up converter into that footprint. Using 1950s technology. Bloody "authenticity" nuts.)

Comment Re:Beware public charging stations... (Score 1) 229

Getting caught Carrying one of these into an airplane may get you a few years behind bars though, as they are close in design to a stun-gun.

FTFY

Since it's full of RF-passive components (the design is inherently for a "physical access" attack, not a "remote access" attack), it's going to look like - a USB device full of blocky electronic components. Even on X-rays. So, you're down to having either a blanket ban on portable electronics air-side, or the judgement and experience of the security staff to recognise the "Chthulu-a-like" logo. So, no protection there then.

Scattering these in the taxi drop-off area of the airport - or even better in the smoker's corner - would provide plausible deniability for anyone caught carrying one. If Big Brother know that you actually brought one already ... well, you've got bigger problems than getting caught with one of these.

Quick look in my flying bag - 9 USB devices of different makes all broadly similar in design to this. Including a couple of USB GSM modems for different countries.

Actually, rigging up an adaptor to turn one of these into a stun-gun ... certainly should be doable. Though with only 220V, would it provide enough belt to actually stun someone? Hurt someone - sure. Be noticeable - well, who here hasn't take a few 240V belts off the mains? Died? Far fewer. It takes something like 40mA across the heart to reliably kill someone, which takes some care to set up. To get 40mA off 220V, you'd need a circuit resistance of less than 5k5 Ohms ; skin resistance is on the order of a megaOhm/m, so you'd need your contacts just a few mm apart. Which would give you penetration of the same sort of distance down into the conductive body tissues. You could annoy someone with this, but causing real damage would be pretty hard.

Comment Re:Bad Headline (Score 1) 563

That's the way it is being used, as a proxy for race.

So when the USofTrump introduces apartheid laws registering people into "black", "white" and "coloured" races, banning miscegenation, defining the amount of "blood" content before you move into a "lower" race (e.g. 1 part in 8, or 1 part in 16 for one non-white great grandparent or great-great grandparent ; not important for combinations not involving white majority), defining the physical characteristics for initial characterisation of the elderly (their descendant's races then being defined) ... have I forgotten any of the significant laws that will be necessary? The details can be found in the law codes of South Africa and several of the US states.

Anyway, once the racial apartheid laws have been passed, the fickleness problems of classification by religion simply won't be necessary.

I think they'll go directly to apartheid, and the "Muslim database" would simply become unnecessary. For example, Richard "Shoe Bomber" Reid would be prevented from flying for being 1 part in 2 black, not because of having converted to Islam in his 20s.

Slashdot Top Deals

A company is known by the men it keeps.

Working...