seriously disabled

There is some concern that the LHC could produce stable strangelets, elementary particles of a substance thought by some physicists to live in the core of a neutron star.

Wikipedia says that there is no danger of the LHC producing stable stranglets because the probability of the creation of stranglets decreases at higher temperatures. Here another reference written for the layman says the same.

What I don't get is why does the probability of the creation of strangelets decreases at higher temperatures when inside the core of a neutron star temperatures can reach 10 billion kelvin but there stranglets are supposed to be produced?

According to Wikipedia nanoelectronics holds the promise of making computer processors more powerful than are possible with conventional semiconductor fabrication techniques.

A number of approaches are currently being researched, including new forms of nanolithography, as well as the use of nanomaterials such as nanowires or molecular logic gates in place of traditional CMOS components. Field effect transistors have been made using both semiconducting carbon nanotubes and with heterostructured semiconductor nanowires.

More on this topic:

http://en.wikipedia.org/wiki/Nanoelectronics

http://www.tutorialsweb.com/nanotech/page-5.htm

http://www.springerlink.com/content/p1l7m7x66075741g/

because thats what they called it. maybe it reminded the guy of some sort of seed dispenser and so he called it that and the name just stuck. this stuff happens.

But if the rotating cylinder looks something like this,

then how do the seeds remain on the walls of the cylinder? Why do they not simply fall from the walls and mix with the propellant fluid?

The answer is in your question (in parenthesis).

But why is it called a seed?

In the wikipedia article on solar thermal rockets they write that: "Direct solar heating involves exposing the propellant directly to solar radiation. The rotating bed concept is one of the preferred concepts for direct solar radiation absorption; it offers higher specific impulse than other direct heating designs by using a retained seed (tantalum carbide or hafnium carbide) approach. The propellant flows through the porous walls of a rotating cylinder, picking up heat from the seeds, which are retained on the walls by the rotation. The carbides are stable at high temperatures and have excellent heat transfer properties."

What is a retained seed? Is it a crystal?

I fail to see how this could be a weapon of mass destruction, please elaborate if you have anything specific to collaborate this.

 

Cosmic rays routinely hit the earth at energies many orders of magnitude greater than the energies from the LHC, and there are no problems from these. The LHC is buried deep underground, there is simply no way for any particles or energy from the LHC to be focused anywhere except the specific location of the LHC. People who are not standing within the LHC (and access to it is, I'm sure, restricted), then are safe from the radiation and particles generated by it. Frankly, there is no possibility of harm from the LHC.

So does Ivan Gorelik's theory on magnetic holes (aka magnetic trap) raise a serious risk or is it plain crack?

Do you have any idea how little of an element can be made via a particle accelerator? Even if it was the most toxic thing know, it would pretty much be harmless due to such a small quantity. Also, they don't call them atom smashers for nothing.

I also don't think the LHC is so dangerous as Ivan Gorelik makes it out to be. However I do believe the LHC is potentially a world class weapon of mass destruction, whereas all possibilities need to be taken seriously because we're really entering into new territory here.

Ivan Gorelik (aka Magnetic) thinks the LHC could produce a magnetic trap, also called a magnetic hole which would consume the earth in a few minutes. Respectful physicists call him a clown and in this case I really hope the clown is dead wrong.

The definition of the Coloumb is the amount of electric charge transported in one second by a steady current of one ampere. Mathematically it's written as:

[math]1 \mathrm{C} = 1 \mathrm{A} \cdot 1 \mathrm{s}[/math] or [math]1 \tfrac C s \cdot 1\mathrm{s}[/math]

The defintion of Ampere is one coulomb of charge going past a given point per second: [math]\rm 1 A=1\tfrac Cs[/math]

My question is: Why is the defintion of the Coloumb not written as [math]1 \mathrm{C} = \frac{1\mathrm{A}}{\mathrm{s}}[/math]

An international team of researchers may, just may, have made a radical breakthrough that could rewrite physics and chemistry textbooks.

They claim to have discovered a naturally occurring element with an atomic number (number of protons) of 122 — 30 notches on the periodic table ahead of uranium, long considered the heaviest naturally occurring element.

For decades, physicists have been making artificial elements in supercolliders, only to see most of their creations disintegrate within a short time.

Most elements above atomic number 100 are inherently unstable and get progressively more usntable as you travel upward. The highest discovered one, ununoctium or atomic number 118, has a half-life of 89 milliseconds.

But according to theory, there exists an "island of stability" further out along the periodic table where certain configurations of protons and neutrons would create superheavy but also superstable elements.

So a team led by Amnon Marinov of the Hebrew Univ. of Jerusalem took a different approach. They figured that if superheavy, superstable elements really are possible, then they ought to already exist in nature.

Taking a relatively large amount of thorium, a natural element with the atomic number 90, they fired each and every nucleus in the pile through a mass spectrometer, which catches the atomic weight of nuclei (protons plus neutrons) by analyzing how beams of ions pass through them.

The two isotopes of thorium, with atomic weights of 230 and 232, were most abundant, as were various impurities in the sample.

But there was something else—something with an atomic weight of 292, something never before seen.

The researchers aren't certain, but they figure their unknown substance probably has an atomic number of 122, whose slot on the periodic table already has the temporary name "ununbibium," or "one-two-two-bium."

They also figure its half-life is at least 100 million years—meaning the shores of the long-sought "island of stability" may finally have been reached.

They're ruled out various errors, and are ready to defend their paper, posted Thursday on the math and physics Web site arXiv.org:

Superheavy element found

The hunt for superheavy elements has focused banging various heavy nuclei together and hoping they’ll stick. In this way, physicists have extended the periodic table by manufacturing elements 111, 112, 114, 116 and 118, albeit for vanishingly small instants. Although none of these elements is particularly long lived, they don’t have progressively shorter lives and this is taken as evidence that islands of nuclear stability exist out there and that someday we’ll find stable superheavy elements.

But if these superheavy nuclei are stable, why don’t we find them already on Earth? Turns out we do; they’ve been here all along. The news today is that a group led by Amnon Marinov at the Hebrew University of Jerusalem has found the first naturally occuring superheavy nuclei by sifting through a large pile of the heavy metal thorium.

What they did was fire one thorium nucleus after another through a mass spectrometer to see how heavy each was. Thorium has an atomic number of 90 and occurs mainly in two isotopes with atomic weights of 230 and 232. All these showed up in the measurements along with a various molecular oxides and hydrides that form for technical reasons.

But something else showed up too. An element with a weight of 292 and an atomic number of around 122. That’s an extraordinary claim and quite rightly the team has been diligent in attempting to exclude alternative explanations such as th epresence of exotic molecules formed from impurities in the thorium sample or from the hydrocarbon in oil used in the vacuum pumping equipment). But these have all been ruled out, say Marinov and his buddies.

What they’re left with is the discovery of the first superheavy element, probably number 122.

What do we know about 122? Marinov and co say it has a half life in excess of 100 million years and occurs with an abundance of between 1 and 10 x10^-12, relative to thorium, which is a fairly common element (about as abundant as lead).

Theorists have mapped out the superheavy periodic table and 122 would be a member of the superheavy actinide group. It even has a name: eka-thorium or unbibium. Welcome to our world!

This may well open the flood gates to other similar discoveries. Uranium is the obvious next place to look for superheavy actinides. I’d bet good money that Marinov and his pals are eyeballing the stuff as I write.

The paper, “Evidence for a long-lived superheavy nucleus with atomic mass number A = 292 and atomic number Z @ 122 in natural Th” is available here:

Source:

http://arxiv.org/pdf/0804.3869v1

http://www.rdmag.com/News/2008/04/Researchers-claim--discovery-of-superheavy-element--ldquo;unbibium-rdquo;/

http://www.scientificconcerns.com/Forums/viewtopic.php?f=2&t=2053&hilit=superheavy&start=20

My question is: Could the LHC produce new superheavy elements which don't decay and which could pose a risk to us?

I didn't know where to put it but I think it belongs best to electronics.

In How a Projector works? they write that the composite video and S-video signals are routed to a Video Decoder circuit. Most digital projectors include a video decoder and a light engine. The video decoder converts video data received by the projector into pixel and color data.

My question is: How exactly does the video decoder do this conversion?

Ok I get it now. Thanks a lot for the explanation guys!

What does the prefix 0x (as in 0x565) mean in the hexadecimal numeral system? What is this prefix for?

Similar phenomenon are at play when we crave other things like proteins or foods with certain minerals/vitamins.

So what is the similar phenomenon in this case?

It really doesn't(calories are just a unit of energy). It does, however know if it's lacking sugar, but that's rather irrelevant to the craving. If we only craved high calorie food when we're low, the US wouldn't look like it does.

So how does the body know it's lacking sugar or that it needs certain foods?

It's mostly personal preference, but there is an evolved tendency toward craving food with a high caloric density.

Ok thanks but how does the body know it's lacking calories?

How does the body know what it wants or needs to eat? Whether it wants piza, a hamburger or a steak?

How does the body know it is missing those things or whether it's lacking certain vitamins or minerals found in certain foods?

How does the brain form a full-color mental image of an object, person or event when the relevant object, event, or scene is not actually present to the senses?

But why does the light need to be polarized in the first place?

So you can display color images — varying levels of R, G and B allow you to display many colors.

 

A static system isn't able to assess the technical level of its audience, and HSW is reaching out to a more basic audience. That doesn't make them a fraud.

 

Wikipedia has more

 

http://en.wikipedia.org/wiki/Liquid_crystal_display

But what is the orientation film for?

What type of screen would you like to know about? (I'd also suggest having a look at howstuffworks.com)

Liquid crystal screens of course.

And after a quick internet search I came up with this image:

What I don't completely understand is what the color filters are for?

Howstuffworks is a fraud. They explain things in a very simplistic level but they don't delve enough into the technical details. They don't explain the underlying physics of liquid crystal displays and they don't explain what the materials of the screen are made of.

I know that each pixel is composed of 3 subpixels. But what are the three subpixels on the screen made of? What is their internal structure?

In digital-to-analog converters, what is charge redistribution? Does it have something to do with switched capacitors?

In the book Liquid crystal display drivers: techniques and circuits by David J.R. Cristaldi, on page 210 they mention something called an offset compensated redistribution DAC?

Could someone explain what an offset compensated redistribution DAC is?

Formal spec can mean a lot of things.

 

It almost sounds like you want a C++ model checker:

 

http://www.cprover.org/cbmc/

 

Aside from that, you cannot formally specify C++ programs, because C++ is a quasi-superset of C, and C has "dangerous" semantics.

But what is a quasi-superset and what is dangerous semantics?

Is this for a class?

No it's not for a class. It's just something I'm interested knowing.

If you want to write a formal specification of a program written in C++ or Java, then how can you know the logic of the C++ program you've written?

I searched the Internet for books which rigorously teach the subjects of semantics of programming languages and formal specification and I couldn't find any and the three I did find are not rigorous and are quite out of date.

Merged post follows:

I'll phrase my question differently.

Let's say I wrote a program in C++. How do I create a formal specification of the program I've written?

Two popular specification languages are the Z notation and VDM (Vienna Development Method). So if I wrote my program in C++, does it mean I have to translate the C++ program to Z notation or VDM? But how do I do that?

Do I need to know the semantics of C++ in order to do this? I searched the net for books which teach the semantics of C++ but couldn't find any.