Recent content by Pieter Kuiper

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    Who had the means and motive to use Polonium-210 as a weapon?

    So it seems it was not sushi, but tea. Hot tea. About doses: http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/01/11/npoison111.xml
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    Who had the means and motive to use Polonium-210 as a weapon?

    "Litvinenko's killers used polonium worth $10m" http://www.timesonline.co.uk/article/0,,3-2509789,00.html Desinformation, of course. Here is a company that makes antistatic devices based on polonium: http://www.nrdstaticcontrol.com/FAQ.asp According to the Swedish newsper 'Ny Teknik', NRD...
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    Who had the means and motive to use Polonium-210 as a weapon?

    Some new numbers on Scaramella's dose from http://www.bloomberg.com/apps/news?pid=20601102&sid=ae13ie5Ij2oY&refer=uk : So they were asking good questions, but the answers do not really add upp - as the reporter seems to be very well aware of.
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    Who had the means and motive to use Polonium-210 as a weapon?

    Finally I found a number about the dose - a massive overdose: http://www.timesonline.co.uk/article/0,,2087-2484295_1,00.htmlEdit: And Scaramella is now reported saying: At first his radioaktivity was not detectable... Maybe doctors told him that he has five times the maximum allowable burdy...
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    Who had the means and motive to use Polonium-210 as a weapon?

    From a good article in the New York Times: http://news.google.com/news/url?sa=t&ct=uk/0-2&fp=45724b49d5e1b4b9&ei=9a9yRcfzK8SGwwGIuNGKCQ&url=http%3A//www.nytimes.com/2006/12/03/weekinreview/03broad.html&cid=1111251378 (requires registration)
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    Who had the means and motive to use Polonium-210 as a weapon?

    Professor Nick Priest says a giga-becquerel ("no more than a few micrograms"). http://www.newscientisttech.com/article/dn10668-exspys-polonium-poisoning-suggests-sophistication.html "A lethal dose for ingestion or inhalation by a human being would be between 500 and 5,000 microcuries, according...
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    Who had the means and motive to use Polonium-210 as a weapon?

    I was wondering how much one would need for a lethal dose. From a link that I found on Wikipedia: "Rats injected intravenously with a lethal amount of 210-Po (1.45 MBq/kg body mass) died within 14-44 days." http://dx.doi.org/10.1080/095530097143338 I would guess that this is of the same order...
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    That guy who made his own reactor

    There also exists a tv documentary: http://www.imdb.com/title/tt0378468/ Quite interesting. If there really was in increase of the thorium activity, it must be attributed to the growing amounts of radioactive thorium progeny after Hahn had isolated the material from lantern mantles.
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    Excite Rotational & Vibrational Energies Simultaneously

    In a gas at room temperature, molecules will be in many states with different rotational states with rotational angelar momentum larger than zero. Now, if they absorb an IR-photon, the moment of inertia will change. Angular momentum is conserved, så the rotational frequency must change...
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    20 Years of High Temp Superconductors

    You mean liquid nitrogen (at those temperatures there is noise). Helium is required when one wants to make strong magnets of these materials.
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    Which Bond is Stronger: Metallic or Covalent?

    Covalent bonding is also important in transition metals. It is difficult to distinguish between these contribution. It is all calculated by the same programs. When considering bonds, one might take into consideration that carbon i diamond only has only four bonds to nearest neighbours, where...
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    Understanding Electron Binding Energy for Multi-Electron Atoms

    One can do total-energy calculations of atoms and molecules (Density Functional Theory). From the differences, one can compute ionization energies and excitation energies.
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    How does light travel through air molecules?

    No. You can see this at a surface: some is reflected. In point scattering (of an individual molecule) there will be scattering in all direction. But only in the forward direction, contributions will be in phase. The description of light as a stream of photons complicates this kind of questions...
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    How does light travel through air molecules?

    It is actually not so simple. Air is mostly empty space, but so is iodine vapor, which is rather brown. In a wave picture, the electric field induces an electrical polarization of the molecule. Unless there is absorption, this polarization is out of phase with the driving field. The...
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    Energy distribution and Maxwell speed distribution

    There is only one state with energy zero, but in three dimensions there is a "sphere" of states with energies larger than zero. The surface of this sphere increases with energy.
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