Study of the Depolarized Light Scattering Spectra of Supercooled Liquids by a Simple Mode-Coupling Model

By using simple mode coupling equations, we investigate the depolarized light scattering spectra of two so-called "fragile" glassforming liquids, salol (phenylsalicylate) and CKN (Ca_{0.4}K_{0.6}(NO_3)_{1.4}), measured by Cummins and coworkers. Nonlinear integrodifferential equations for the time evolution of the density-fluctuations autocorrelation functions are the basic input of the mode coupling theory. Restricting ourselves to a small set of such equations, we fit the numerical solution to the experimental spectra. It leads to a good agreement between model and experiment, which allows us to determine how a real system explores the parameter space of the model, but it also leads to unrealistic effective vertices in a temperature range where the theory makes critical asymptotic predictions. We finally discuss the relevance and the range of validity of these universal asymptotic predictions when applied to experimental data on supercooled liquids.Comment: 31 LaTeX pages using overcite.sty, 10 postscript figures, accepted in J. Chem. Phy

A Pressure-Induced Incommensurate Phase in Ammonium Hydrogen Oxalate Hemihydrate

We report evidence for the existence of a new incommensurate phase in a crystal of ammonium hydrogen oxalate hemihydrate. This phase is remarkable in two aspects: it exists only above a critical pressure Pc, and the incommensurate wave vector, which is parallel to the vector c* of the reciprocal lattice, has the largest variation ever reported, varying continuously from 0.147c* at 4.3 kbar to ~ 0.25c* at the maximum pressure (8 kbar) used to date

Výzvy vyvolané aplikací mezinárodního humanitárního práva na informační válku

In wartime, information is essential and decisive for the conduct of hostilities. It is the foundational element of intelligence, the basis of the war narrative galvanising the society but also, a weapon. International humanitarian law acknowledged the strategic importance of information, regulating the involvement of spy and journalists in armed conflicts. Information has gained an increasing place in the military strategy and in the academic debates because of various factors, including the development of new information technologies, the emergence of the phenomenon of 'information warfare', the growing interest of the political analysts for 'hybrid warfare' after the Crimean crisis in 2013 and the sociological context of 'post-truth'. In a context of ever-changing technological environment, the application of the current international humanitarian legal framework to information warfare is full of challenges and raises unanswered questions. Hence, this dissertation aims at answering the following question: how do the specificities of contemporary information warfare challenge the application of international humanitarian law? This question is particularly relevant now for several reasons. First, one has gained hindsight on marking events of information operations, including the attack on the...Katedra bezpečnostních studiíDepartment of Security StudiesFakulta sociálních vědFaculty of Social Science

Compensation des fluctuations de la source lumineuse d'un spectromètre à détection par photomultiplicateur

Description d'un montage simple qui s'inspire d'un schéma dû à Clink [1] et dont le fonctionnement s'est révélé très satisfaisant, si la lumière est modulée

The challenges raised by the application of International Humanitarian Law to information warfare

In wartime, information is essential and decisive for the conduct of hostilities. It is the foundational element of intelligence, the basis of the war narrative galvanising the society but also, a weapon. International humanitarian law acknowledged the strategic importance of information, regulating the involvement of spy and journalists in armed conflicts. Information has gained an increasing place in the military strategy and in the academic debates because of various factors, including the development of new information technologies, the emergence of the phenomenon of 'information warfare', the growing interest of the political analysts for 'hybrid warfare' after the Crimean crisis in 2013 and the sociological context of 'post-truth'. In a context of ever-changing technological environment, the application of the current international humanitarian legal framework to information warfare is full of challenges and raises unanswered questions. Hence, this dissertation aims at answering the following question: how do the specificities of contemporary information warfare challenge the application of international humanitarian law? This question is particularly relevant now for several reasons. First, one has gained hindsight on marking events of information operations, including the attack on the..

The low frequency Raman spectrum in relation to the phase transition of KH3(SeO3)2

The low frequency Raman spectrum of KTS has been recorded and analysed above Tc at 1 bar and 8 kbars, in the B3g geometry which corresponds to the low temperature static deformation. The spectra clearly show the existence of a proton mode below 50 cm-1; the analysis shows that quantum effects and the proton coupling with an optic mode around 40 cm-1 play minor roles in the transition mechanism. On the contrary, the interaction between the protons turns out to be classical in nature, their dynamics is of the relaxation type (with a relaxation time τ = (27 cm-1)-1) and their coupling with the B3g deformation is very important : all those effects stress the large difference between KH2PO4 and KTS in spite of the large sensitivity, to deuteration, of their critical temperature Tc.Le spectre Raman de basse fréquence de KTS a été mesuré et analysé au-dessus de Tc à 1 bar et 8 kbars, dans la géométrie B3g correspondant à la déformation statique de basse température. Les spectres montrent clairement l'existence d'un mode de proton au-dessous de 50 cm-1 1 et l'analyse établit que les effets quantiques et le couplage des protons avec un mode optique vers 40 cm-1 ne jouent guère de rôle dans le mécanisme de la transition. En revanche, il s'avère que l'interaction entre les protons est de type classique, que ces derniers ont une dynamique relaxationnelle (avec un temps de relaxation τ = (27 cm -1)-1) et que leur couplage avec la déformation B3g est très important : toutes ces propriétés soulignent la grande différence entre KH2PO4 et KTS malgré la grande sensibilité, à la deutération, de leurs températures critiques Tc

Dispositifs pour l'enregistrement graphique du quotient de deux tensions continues et variables

Analyse d'un procédé classique dans lequel on remplace la tension de référence d'un potentiomètre enregistreur par la tension « Dénominateur ». Le calcul montre que le fonctionnement est inacceptable lorsque cette dernière varie dans de grandes proportions et on décrit alors un montage dans lequel cet inconvénient est supprimé. Une réalisation pratique s'est montrée satisfaisante

Spectres de vibration et symétrie des cristaux de perchlorate de baryum Ba(Cl O4)2, 3H2O

A detailed study of the Raman scattering spectrum leads to the choice of the point group 6 instead of 6/m.L'étude détaillée du spectre de diffusion Raman conduit à attribuer à ces cristaux le groupe de symétrie 6 et non 6 /m.Krauzman Michel, Mathieu Jean-Paul, Poulet Henri. Spectres de vibration et symétrie des cristaux de perchlorate de baryum Ba(Cl O4)2, 3H2O. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 95, 5, 1972. pp. 538-540