La aparición del magnetismo en nanopartículas (”quantum dots”) de materiales que normalmente no son magnéticos es considerado como uno de los grandes descubrimientos de la nanotecnología. Nanopartículas que se comportan como imanes permanentes (ferromagnéticas) para memorias de estado sólido basadas en nanoimanes. Muchos investigadores lo creen así. Puede que estén completamente equivocados. Un estudio reciente ha mostrado que el magnetismo en estas nanopartículas es debido a los elementos químicos que se ligan a sus bordes. Han estudiado nanopartículas de cadmio-selenio (CdSe) y han observado que son paramagnéticos (su magnetismo inducido es sólo temporal) y no ferromagnéticos (con magnetismo permanente) como se había afirmado en estudios anteriores. Al no ser imanes permanentes, su utilidad en memorias magnéticas de altísima escala de integración se ve muy mermada. Nos lo cuentan brevemente en “Chemistry: Mini magnets,” Nature 459: 302-303, 21 May 2009 , haciéndose eco del artículo técnico Robert W. Meulenberg et al. “Evidence for Ligand-Induced Paramagnetism in CdSe Quantum Dots,” J. Am. Chem. Soc. 131 : 6888–6889, May 5, 2009 .

Las nanopartículas semiconductoras son extremadamente pequeñas, por ejemplo, las de CdSe tienen un radio medio entre 0.13 y 0.15 nanómetros. Estudios previos han mostrado que muchas nanopartículas exhiben un comportamiento ferromagnético en forma nanocristalina, como las de oro (Au, metal 5d⁹) . ¿Por qué si en forma normal no lo hacen? Se han propuesto diferentes mecanismos físicos para explicar estas propiedades pero no es fácil explicar el porqué. Ciertos estudios atribuyen estas propiedades magnéticas a defectos o errores en el experimento. Lo que se piensa que es un nanocristal puro en realidad no lo es y está ligado a impurezas de origen químico. El nuevo estudio, si se confirma, muestra de forma conclusiva que el magnetismo en las nanopartículas de CdSe se puede manipular (inducirlo y destruirlo) utilizando dopantes químicos, mostrando un comportamiento paramagnético pero no ferromagnético.

Lo dicho, si se confirma este estudio, las ilusiones de muchos por obtener memorias de estado sólido de ultraalta escala de integración se pueden esfumar. ¿A alguien se le ocurrirá como superar esta barrera?

I’ve just come across a really interesting post by a guys named Harry on the place of philosophy in the humanities and the general academic discipline.  The whole post is here. As a teaser, here are two paragraphs that seem to right true:

. . .Philosophy seems to be an outlier within the humanities, just as Linguistics is; we have less in common with the other humanities in terms of the concepts and methods that we deploy, and even the subject matter, than they have with one another (I don’t think I could make the case for that claim in a rigourous way, but I’m convinced its true). Some philosophers, furthermore, seem largely uninterested in any other kind of intellectual endeavour, and this just increases the sense of the other humanists that wee are arrogant; worse still, those of us who are interested in other disciplines frequently look to the sciences and social sciences rather than to the rest of the humanities (speaking for myself, I read history and literature for fun, but I read sociology and economics for work). The final problem philosophers have is, as Jason Stanley points out, that the term “philosopher” has more than one legitimate use in English, such that “it is not unusual for English professors to describe themselves as philosophers”; those who do, in my experience, do not have much contact with people who work in philosophy departments, even when it would be very easy for them to have contact. . .

. . .I doubt the situation is good, either for Philosophy, or for the rest of the humanities. And not only because it makes it hard for philosophers to get grant proposals accepted. I’ve frequently been struck, when reading grant proposals from other humanities disciplines, how they could have been enriched by interaction with philosophers, whose input would have helped people to structure arguments better and perhaps to see problems that they gloss over. When I read proposals with some moral or ethical dimension I almost always know philosophical literature that is accessible and seems to me vital for thinking clearly about the matter at issue, and would help the scholar to distinguish the various reasons they have for thinking something they want to argue for. . .

I’m going to be making the case in a later post that the seemingly irreconcilable differences between the humanities, philosophers, and the sciences are based on these three areas selecting for different cognitive profiles.  In essence, a scientist with a different cognitive profile from a philosopher can’t truly understand the significance of the philosopher’s work, even if he can understand the basic reasoning behind the philosopher’s work.

I stumbled upon this post from Uncertain Principles about the differences between humanities and science writing.

Prof. Orzel is discussing the values of primary versus secondary sources, and why primary sources are not as important in the physical sciences.

He says “The difference here is in what’s being studied. The physical sciences are studying the nature and behavior of the universe, which isn’t something that’s written down. The analogue of reading a primary source would be doing an experiment, not reading anything.

“In most humanities disciplines, though, the text is the point. As a result, the distinction between primary and secondary sources is critical. The whole point of the business is to read and interpret primary sources– trying to produce humanities scholarship without reading the original texts is like trying to do science without experiment or observation. It’s the humanities equivalent of string theory.”

“Thus, I’m not terribly concerned about the failure to read original sources in physics theory.”

Read full post.

Granted I do not study physics theory, but I have to scratch my head at his analysis of the differences between the sciences vs. humanities. In “crossover” disciplines like archaeology and biological anthropology there is a lot of experimenting that is done. Yet it is also considered critical in these disciplines to read the primary source. Taking a secondary source’s word that the original experiment or data was a flop is not good enough. It is  considered vital to read the original researchers paper, to look for clues that the original guy or gal may have missed. And if you can get your hands on a field report, you’ve won the jackpot!

And I honestly believe a lot of confusion would be cleared up if more people actually read Darwin’s theory on evolution.

I suppose it depends on the degree of interpretation going on. When English majors are asked to interpret Dante’s The Divine Comedy, then of course they’re going to have to read the thing, or at least the cliff notes.

But overall I think the Prof. paints too broad a picture. Thoreau, the blogger who started this whole discussion, seems to be a little more open to the idea of reading the original text:

“There’s a lot of history behind [physics theory], with the older theories (usually) being taught first.  We also engage in a ton of hero worship, telling all sorts of stories about the great physicists.  (A few of those stories might even be true!)  Despite all that reliance on history and that culture of revering our great predecessors, we never sit down and read the original works, a habit that would be second nature to a humanities scholar.

“I’m not saying we should always do that, or add a bunch of original works to an already-crowded curriculum.  But it is interesting just how rarely we do it.”

I think that the physical sciences could use a little more historical context, and at least an effort to encourage the kiddos to read the original stuff.

I just handed in the final copies of my thesis this morning. So I’m officially done!

The thesis defense yesterday was embarrasingly bad, I’m so glad they didn’t fail me for it. I was up the whole night before the defense writing a paper for another class, and I didn’t get good sleep on the days before that either. So I went in for the three hour long thesis defense with zero preparation and minimal sleep. And it was bad. It didn’t take 3 minutes before the profs started asking me questions that I had no idea how to answer. I would just freeze up for minutes at a time, and they would have to guide me through every single step of the answer, it was pathetic. I couldn’t even do simple algebra on the darkboard, and I forgot all the physics theory I’ve ever learned, I couldn’t even remember the first law of thermodynamics, let alone any quantum or stat mech! It was that bad.

Well, apart from that anticlimatic end to my college career, I’m kinda feeling quite relaxed.

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Originally uploaded by kgigante

Are you a Superhero? If so, I’m sure you have done a lot of shopping here! Superhero in Training? Then please stop by the Superhero Supply Company to stock up! I guess this is a real store where they actually sell products (not really sure what is in the can of gravity though). You can by a lair as well. Save your pennies!!!

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Originally uploaded by kgigante

This is the cover of a book I bought yesterday at a book fair. It is pretty ‘cute!’ There are characters for many concepts in physics theory. I think my favorite illustration is the one for Schroedinger’s Cat. If I find a picture I can post of that I’ll do that soon. The book is in my classroom so you can check it out any time you wish.  More information here and here.

Archeaologists have found “Eve“.