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* Posts by Chemist

1879 posts • joined 24 Mar 2010

Royal astro-boffin to MPs: Stop thinking about headlines

Chemist
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"those food additives are"

Incidently the most dangerous contaminants of food are natural, although generally caused by poor storage etc. Materials like aflatoxins ( must be less than 20 ppb in food) make many man-made poisons, let alone food additives, look quite bland.

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Chemist
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"Carcenogens in food are a massively more important issue"

Carcinogens in food ARE an important issue - but are they actually a significant risk?

Lots of things are easy to measure to measure to extremely low levels e.g certain chemicals and ionizing radiation. Problem is assessing the consequences.

With carcinogens a 'predicitive' test that has been used widely is the Ames test named after its inventor, which actually show the mutagenic effect of a chemical. Find an active and the supposition was that almost no level was 'safe'

Years later Bruce Ames published a long review of carcinogenic challenges and demonstrated that biological systems have a threshold level below which almost no damage is important and the system generally self-repairs.

So carcinogens are important but the risks are probably far lower than the popular perception.

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US Navy preps railgun for tests

Chemist
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Of course

if you make it into a sieve it will sink but it seems rather far fetched to assume that it will be hit a sufficient number of times BELOW the waterline. If its a small vessel then game over and if the projectile hits something heavy or critical that it can vaporise/ be vaporised by then ditto.

100000 tons takes a lot of sinking with small holes.

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Chemist
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It still has to hit something solid

Most modern warships have relatively thin hulls. Such a slim projectile needs to hit something with substantial mass to impart a good proportion of its energy otherwise it will just go through like a rifle bullet through paper. There might be local damage but it could easily be insignificant to a ship-sized object.

Its also an unguided shell equivalent so it need to follow a ballistic curve and allow for the curvature of the earth. This is likely to increase errors in aiming.

For close quarter defence there might be a different picture.

I calculate the 1 ton kinetic energy as ~1.5MJ so there is a large mismatch somewhere

(Imperial AND SI units - urrgh!!)

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Raspberry Pi ship date slips

Chemist
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The open source for x264 ...

is readily available e.g.

ftp://ftp.videolan.org/pub/x264/snapshots/last_x264.tar.bz2

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Chemist
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I assume x264 is an option ?

No hardware assisted encoding but I use it for 1080/50p encoding and it works well, if rather slowly, on anything less then top-notch kit. Playback on VDPAU/Nvidia assisted decode is excellent using ~5-10% cpu even on an old dual core AMD 64

There certainly have been ARM versions

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Boffins crack superconducting graphene's melting mystery

Chemist
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Ah !

You need to use liquid crystal glasses NOT beer goggles

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Chemist
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Regular arrays like that

can produce that effect. I've spent a lot of time looking at 3D chemical graphics of various types over the last 30 years and have got used to the games they can play. If you cross your eyes or defocus them you might well find the images shift around to give the impression that you are looking from below. Try changing the size or darkening the room.

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Demand for safety kitemark on software stepped up

Chemist
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Re : a dozen people

Thanks for that, pity it was so small.

Having done this quiz I guess one problem is that it isn't against the clock so I had plenty of time to scrutinize the pages and particularly the URLs. In some ways it was easy to spot the phishing sites but verifying that a genuine site was genuine was harder - spot the phish and you're done but on the 'good' sites it took more searching to convince me that there wasn't some trick.

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Chemist
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Re: http://www.opendns.com/phishing-quiz

But how many people did your survey cover ?

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Chemist
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"If you looked at the email"

Not on my system mate

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Five ways Microsoft can rescue Windows Phone

Chemist
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"The market needs the competition."

Just like the desktop ?

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MasterCard joins Visa in pushing PINs into America

Chemist
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French motorway tolls

Just card in/out - no PIN

Spent ~£380 recently going Calais-Switzerland-Riviera-Auvergne-Calais with the largest single item ~£40 all without PIN or signature - I guess they have the reg. plate captured though.

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OFFICIAL: Smart meters won't be compulsory

Chemist
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Quite the reverse here

Both electricity/gas I put the readings in on-line, bill gets paid by DD, meterman turns up about a week later. Being going on for ~ 2/3 years

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Trojan smuggles out nicked blueprints as Windows Update data

Chemist
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Sorry BigYin

It didn't read like a joke

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Chemist
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@Vic

Same here

OpenSUSE 11.4

sudo version 1.7.6p2

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Star Trek tractor beam to save Earth from asteroid Armageddon

Chemist
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"Anything that claims to be edgy should be taken outside and shot."

Edgy :-

"daringly innovative; on the cutting edge. "

Your point is ?

And I have been on this site for a number of years. And there does seem to be a tendency for posters to get their facts wrong - often wildly so.

Recently someone claimed that the NEO was 6 miles in diameter where most info sources were saying ~11m or bus sized

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Chemist
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"near miss was something over 6 miles in diameter, "

er ? 11 metres is closer

BBC

"The asteroid, estimated to be about 11m (36ft) in diameter, was first detected on Wednesday."

CBS

"A small asteroid the size of a city bus zoomed between Earth and the moon's orbit Friday (Jan. 25)"

I agree about the nuck though

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Chemist
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"since the electromagnetic force is tiny compared to the force due to gravity and mass"

Quite the reverse.

A charged comb will lift a feather ( against the force of gravity) but the uncharged comb doesn't

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Chemist
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Re : "Put a huge solar parachute or sail on the damn thing."

I think the problem is that the rock is most to be both an irregular shape and likely to be tumbling so to attach any form of propulsion to it and then stabilize and steer it is going to be mighty hard

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Chemist
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@John Smith 19

It does sound fanciful doesn't it ?. Nevertheless that is exactly what is being proposed in the document referenced in the article under the title "Gravity Tractor"

"..minimize fuel consumption and maximize the asteroid’s deflection? What are the trade-offs between the mass of the tractor, the distance between the tractor and the NEO, the control laws, and the time required to produce the required deflection? Reliability is a crucial issue given the long periods (several years to a decade) typically required for gravity traction to produce the required deflection. What are the requirements for autonomous spacecraft control procedures to manage hovering station keeping and maintain stability of the traction system over a long period of time in the (verynearby) presence of an irregular rotating mass?"

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Chemist
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"parking a massive object"

That is indeed what is being proposed although the object would have active propulsion to slowly 'tow' the NEO away from a collision course.

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Chemist
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To be frank

There are enough misguided souls on this site who seem to believe almost anything they are told. It's one thing to be a lively, edgy tech. site - quite another to be an off-shoot of the Daily Mail

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Chemist
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"tractor beam"

Will you STOP using this wildly inaccurate description of the actual proposal !

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Dumb salesmen are hurting us – Nokia CEO

Chemist
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"that in any sufficiently complex software system........everything open source."

e.g. the Linux kernel Oh wait !

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Met Office cuts off Linux users with new weather widgets

Chemist
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"knowing full well that Linux support never has been high on..."

And yet we still use it - I wonder why

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Chemist
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"Foresight is cheaper than development "

Agree entirely.

As a Linux only user I might be devastated by this news except I don't use Met Office widget for Firefox anyway.

"but that involves at least one more click than usual" - er ? Bookmarks anyone ?

As for iPlayer - simples use get_iplayer instead

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Boffins make graphene micro-distillery

Chemist
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"how it would let water through but not helium "

It's not clear to me how the layers are orientated bu it looks as though the graphene sheets are stacked "vertically" |||||| so that the water has to move along between the sheets. If these have hydrophilic groups and have dimensions that just allows water to move through the spaces then other materials may well have problems as there will be a strong tendency for water to fill the spaces and repel any other molecules. In this situation the water will behave quite differently to bulk water - it'll be more like a sloppy ice where every water molecule that evaporates from the low humidity end will need to be replaced from the high end to maintain the energetics.

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Chemist
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selectively allows H2O to pass

I guess it well might. Even chemistry is different with deuterium. The rates of reactions are generally slower and drugs with a hydrogen replaced by deuterium at a point of metabolism are usually metabolised significantly more slowly.

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Newt Gingrich wants Moon to be 51st US state

Chemist
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Re : After burning up on re-entry !

So some people think that a heat shield, steering mechanism and parachutes are going to be feasible for 20000 tonnes of iron ore or whatever

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Chemist
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"a dynamic governor at moon base alpha"

To manage all the telephone sanitizers and hairdressers that'll be arriving soon after.

HHGG

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Untangling the question of antimatter mass

Chemist
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Unfortunately...

the article keeps banging on about mass difference e.g " live long enough to measure the positron’s mass" or "one such possibility – that matter and antimatter have different mass."

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Chemist
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Now I'm just a chemist but ..

We know the mass of an electron - if the energy from electron/positron collision is not twice the equivalent of the electron mass then doesn't that give the answer directly ?

Any physicist care to comment ?

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Node.js sees Windows compatibility as key to success

Chemist
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Exactly

The other quote :"Cross-platform support is essential to avoid being locked into a particular technology.”

Like Office ?

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Poll: Linux's big data guzzling worries melt away

Chemist
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If half a million Linux devices are activated every day

Sorry I find that a poor example - the data isn't "under one roof" and available to anyone on the CERN network.

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Chemist
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CERN

The LHC is going to generate 15PB of data per year.

Their GRID computer :-

Number of machines: 14,972 processors with 64,623 cores running Linux

Some facts about storage capacity (November 2011):

Tape: 41 PB of data, including non LHC data. (Source)

Disk: 62K hard drives with a total capacity of 62660 TiB. RAID is used to increase redundancy and stability. (Source)

That sounds like quite big data

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Microsoft blames poor Windows sales on PC slump

Chemist
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"I've noticed a trend of people my age and up (30+)"

I've noticed it too.

Maybe it's the fact that they have hardly been exposed to anything else.

When I think of the bare board micros , ROM Basic, .... Amiga, Forth, PC, Linux that I've been exposed to as an amateur let alone the terminal/mainframe, PDP11, VAX, Linux workstations and farms in my professional life I guess anyone 50+ has lived through a lot of changes.

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Chemist
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"And I acquire another quick box "

Ditto but with OpenSuse on it

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Windows 8 will show where it likes to be touched

Chemist
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Definitely not Intel inside..

but otherwise I can't check as the waste bin in question is ~900 miles away at the mo.

May have been "Designed for WIndows XP" or some such nonsense.

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Chemist
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last PC laptop I bought

I used the "Windows inside" sticker to adorn the lid of a waste bin

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Sikorsky plays killer copter sim on SGI Altix UV 1000

Chemist
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SGI Altix UV

It's SUSE or Red Hat Linux or Windows that are available.

From SGI's website

"SGI UV runs unmodified versions of SUSE Linux Enterprise Server as well as Red Hat Enterprise Linux. Microsoft Windows Server 2008 R2 is also supported across the product line"

Not found any mention of IRIX

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NT daddy turns his hand to Xbox

Chemist
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"Your average software guy doesn't have hardware skills"

Maybe not but he will know what he would really like to do and can ask the hardware people to consider possible solutions - think of blitters and barrel shifters etc.

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EU asks why credit cards are so expensive

Chemist
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"As for toll roads"

Paying French motorway tolls is MUCH faster with a card, most people seem to be in the long queue for cash. No PIN needed just card in/out

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Chemist
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"I use it rarely and pay it off as soon as possible"

As indeed do I by variable DD with the exception that I use it as much as possible because the CC company gives cash-back - OK only £75 or 0.5% of all the spend but it's in the right direction

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Windows 8 hardware rules 'derail user-friendly Linux'

Chemist
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"hobby operating system "

That's the 'hobby' system that's used for most supercomputers, a good proportion of servers, most scientific computing, and a good/great proportion of embedded systems & phones ?

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Chemist
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"three years on three different laptops"

I'm genuinely sorry you've had these problems (and of course we're not going to fix them here ) but I can only repeat that my experiences have been universally positive.

Now I'm not an IT professional, although I've been around computers all my working life, and like many scientists need to program out of necessity. As well I build my personal machines and other hardware, so I'm not, perhaps, your average non-IT person either.

I'd suggest using an OpenSuse live-CD so that you can see if your hardware is working before trying to install.

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Chemist
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"who actually compute for a living"

Agreed, before I retired I had a Linux dual Xeon workstation with seriously expensive 3D graphics hardware and so did the ~~100 other computational chemists in the company. This was all backed by a Unix fileserver and several Linux compute farms of ~1024.

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Chemist
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Just to expand that ...

I've installed Linux on about 30 computers over the years since ~1995. Since ~2000 I've never had any problems with installation (usually Suse or OpenSuse but others as well).

Presently I have a Lenovo Celeron laptop on which I'm writing this via a USB 3G dongle, an Asus netbook which also takes the dongle, a dual-core atom fileserver with Samsung laser printer, a single core AMD 64 with a 4:3 display and a dual-core AMD 64 with a 16:9 display, and a dual core Intel at our Swiss holiday home with another 16:9 display

I don't think I could get more diverse than that lot.

Not one problem even with the dongle.

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