29 May 2013

PhD position in soft matter/biophysics

I am looking for a PhD student (the financing should start in fall 2013). The topic is the experimental study of the interaction between membrane inclusions (part of the ANR project MEMINT). See the offer.

The candidate should have a background in soft matter physics, biophysics or physical chemistry. The project is essentially experimental, involving system formulation, sample preparation and alignment, preliminary characterization and detailed study by small-angle X-ray scattering, using both laboratory and synchrotron sources. Experience with data treatment techniques is not required, but can be an asset.

Your work will fit into a multi-disciplinary collaboration, involving specialists in soft matter physics and biophysics (both experimentalists and theorists) as well as chemists. You should be a quick learner and communicate well.




20 May 2013

Mimologiques - III

Outline of Gérard Genette's Mimologics. This is part III in a series; see part I, part II or part IV.

Chapter 10 – Internal Inflection
  • The discovery of Sanskrit and its resemblance to European languages in the early 19th century (starting with Friedrich Schlegel) undermines the Cratylist position: common features (e.g. the st root for immovability) are now seen as genetic, instead of mimetic. Of course, the primal language could still have a mimetic origin, but now the argument is much weaker.
  •  The introduction of comparative grammar (a term coined by Schlegel) shifts the emphasis from the vocabulary to the syntactic structure of languages and hence from names (nouns) to actions (verbs) and to the auxiliary speech parts. Beginning with Humboldt, grammar becomes a science of relations, and not of nomenclature. At a deeper level, the move is from the designated object to the designating subject; this does not as much falsify Cratylism as render it irrelevant.
  • For Schlegel, Indo-European languages are characterized by internal inflection (expressing meaning by changes in the structure of the root), which is superior to derivation. The corresponding "mobility" of the word is a move away from mimetism.
  • All these advances push Cratylism from the domain of science to that of poetry (as seen in Chapter 8 for Nodier).

12 May 2013

Torsion constant of a rod. Dimensional derivation

Diagram of twisted rodThe torsion constant of a circular rod (the torque needed to twist it by a given angle) is easily calculated from the equations of elasticity. Up to a numerical constant, it can also be derived by dimensional analysis, as shown below.
Consider the rod in Figure a), with radius \(r\), length \(L\) and shear modulus \(G\). Its upper end A is clamped. The torque \(T\) needed to turn the free end B is linear1 in the twist angle \(\theta\):
\begin{equation}
T = \kappa \theta
\label{twist}
\end{equation}
Clearly, \(\theta\) depends on \(r\), \(L\) and \(G\). Are these the only relevant parameters? How about the bulk modulus \(B\), for instance? A non-rigorous way of showing its irrelevance is by considering a material with finite \(B\) and \(G = 0\) (e.g. a liquid): in this case the torsion constant is clearly zero2. We can then write:
\begin{equation}
\kappa = K \, G^a r^b L^c
\label{kappa}
\end{equation}

11 May 2013

Mimologiques - II

Outline of Gérard Genette's Mimologics. This is part II in a series; see part I, part III or part IV.

Chapter 5 – Mimographisms
  •  Besides vocal mimesis (adequacy of sound to object), one can also consider mimography: the symbolism of the shape of the written word, which can correspond to either:
    • directly the represented object (hieroglyph) — ideomimography
    • or to the pronounced sound, for phonetic alphabets (e.g. the letter "o" suggests the shape of the mouth when pronouncing the corresponding sound) — phonomimography. In a second step, the sound itself can of course achieve vocal mimesis.
  •  Phonomimography can concern either the resulting sound or the phonation process that engenders it (the position of the organs of speech).
  •  For Rowland Jones, English was an example of ideomimeography, based on a symbolic interpretation of the alphabet. His project is significant for (in Genette's terms): "joining, via graphism, the Cratylian dream of a mimetic intepretation of actual language and the more modern project of a 'philosophical' artificial language". Words are self-contained and transparent, showing their meaning by direct analysis, without recourse to etymology.

10 May 2013

On the definition of marriage

Priceless:

 A household is a business given over to caring for small, temporarily insane people, a business subject to cash-flow problems, endless legal harassments, run by people who expect to have sex with each other, who occupy the same space, and who go nuts when either party has sex with anyone else. Once in marriage, a lot of people try to get out as fast as religious tradition, poverty, or devotion to children permits.

Clark Glymour, What went wrong? Reflections on science by observation and The Bell Curve, Philosophy of Science, 65(1), 1-32, 1998 (free PDF).

8 May 2013

Mimologiques - I

This is only a brief outline, since the text is very rich and no summary can do it justice. I can only give some reading impressions, but my recommendation is enthusiastic. I read the French original: an English version was published in 1995 under the title Mimologics (see a brief review and a second one.) I haven't read the English text so I cannot comment on the quality of the translation (by Thaïs E. Morgan), but it must have required a huge effort, due to the subject matter but also to the particular style (Genette is not above playing the Cratylian game himself).

This is part I in a series. See also part II, part III or part IV.





Cratylism
Genette's question is (at least) as old as Plato's Cratylus: what is the relation between words and the objects they designate? Is it purely conventional, or does it contain an element of "reflective analogy"? In Plato's dialogue these two positions are defended by Hermogenes and Cratylus, respectively, so the latter point of view came to be known as Cratylism, hence the book's subtitle Voyage in Cratylusland (as rendered by Morgan.)

Genette and Eco
 I read this book in parallel with Umberto Eco's The Search for the Perfect Language, since the two topics are intimately related: to be "perfect" (in one of many senses: Adamic, hieroglyphic, onomatopoeic, practical, universal etc.), a language must use the "proper" term; this is the essence of the Cratylist position. Thus, the two works share many references (from Herodotus to Hjelmslev and from Wallis to Wilkins) but their point of view is completely different: where Eco gives a chronological, encyclopaedic and rather conventional overview, Genette is mostly topical,  eclectic and quirky. This may be the reason Eco only cites Genette once, although conceptually  the latter covers a lot of the same ground as the former (and then some).