Loi de position ou durée vocalique?

Cet article défend la « loi de position », selon laquelle les voyelles françaises en syllabe fermée tendent à s’ouvrir, et les voyelles en syllabe ouverte, à se fermer, contre les arguments de Y.-C. Morin, pour qui la qualité des voyelles françaises se rapporte surtout à leur longueur en français moyen. Il est admis que si elle rend mieux compte du vocalisme de certains parlers français que la thèse de Morin, la soi-disante « loi » admet beaucoup d’exceptions en français académique. On peut pourtant dire la même chose de l’hypothèse Morin, et la « loi » se situe d’ailleurs sur un plan différent, puisqu’elle se rapporte au devenir de la langue, plutôt qu’à son état contemporain.The "loi de position", according to which French vowels tend to open in closed syllables, and close in open ones, is defended against Y.-C. Morin's view that the quality of French vowels is above all related to their length in Middle French. It is admitted that although the "law" accounts more satisfactorily for the vowel-system of some French parlers, there are still many exceptions to it in contemporary standard French. However, the same is true of Morin's hypothesis, and in any case, the "law" operates on a different plane, since it relates to a continuing movement within the language, rather than to its present state

Properties of planetary fluids at high pressure and temperature

In order to derive models of the interiors of Uranus, Neptune, Jupiter and Saturn, researchers studied equations of state and electrical conductivities of molecules at high dynamic pressures and temperatures. Results are given for shock temperature measurements of N2 and CH4. Temperature data allowed demonstration of shock induced cooling in the the transition region and the existence of crossing isotherms in P-V space

Dynamics of the magnetic and structural a -> e phase transition in Iron

We have studied the high-pressure iron bcc to hcp phase transition by simultaneous X-ray Magnetic Circular Dichroism (XMCD) and X-ray Absorption Spectroscopy (XAS) with an X-ray dispersive spectrometer. The combination of the two techniques allows us to obtain simultaneously information on both the structure and the magnetic state of Iron under pressure. The magnetic and structural transitions simultaneously observed are sharp. Both are of first order in agreement with theoretical prediction. The pressure domain of the transition observed (2.4 $\pm$ 0.2 GPa) is narrower than that usually cited in the literature (8 GPa). Our data indicate that the magnetic transition slightly precedes the structural one, suggesting that the origin of the instability of the bcc phase in iron with increasing pressure is to be attributed to the effect of pressure on magnetism as predicted by spin-polarized full potential total energy calculations

Microphysical properties of cold frontal rainbands

Observations have been obtained within an intense (precipitation rates > 50 mm h−1 ) narrow cold-frontal rainband (NCFR) embedded within a broader region of stratiform precipitation. In situ data were obtained from an aircraft which flew near a steerable dual-polarisation Doppler radar. The observations were obtained to characterise the microphysical properties of cold frontal clouds, with an emphasis on ice and precipitation formation and development. Primary ice nucleation near cloud top (−55◦ C) appeared to be enhanced by convective features. However, ice multiplication led to the largest ice particle number concentrations being observed at relatively high temperatures (> −10◦ C). The multiplication process (most likely rime splintering) occurs when stratiform precipitation interacts with supercooled water generated in the NCFR. Graupel was notably absent in the data obtained. Ice multiplication processes are known to have a strong impact in glaciating isolated convective clouds, but have rarely been studied within larger organised convective systems such as NCFRs. Secondary ice particles will impact on precipitation formation and cloud dynamics due to their relatively small size and high number density. Further modelling studies are required to quantify the effects of rime splintering on precipitation and dynamics in frontal rainbands. Available parametrizations used to diagnose the particle size distributions do not account for the influence of ice multiplication. This deficiency in parametrizations is likely to be important in some cases for modelling the evolution of cloud systems and the precipitation formation. Ice multiplication has significant impact on artefact removal from in situ particle imaging probes

Design, fabrication, and test of an SRF cryomodule prototype at Fermilab

In support of the Charged Kaons at the Main Injector (CKM) experiment [1], an SRF cryomodule was designed, assembled, and tested at Fermilab. The cryomodule prototype consists of a single niobium 13-cell 3.9 GHz superconducting RF cavity installed in its horizontal cryostat. The prototype was simplified to hold an additional dummy cavity in place of a second 13-cell SRF cavity. Although this cryomodule was originally intended for beamline deflection in the CKM experiment, this first preliminary test aims to compliment existing vertical 3-cell 3.9 GHz SRF cavity testing and also to gain expertise in the field of SRF testing. The cryomodule's thermal and mechanical design is reported. The test process and instrumentation is described. The first operational cooldown with RF powering is discussed and some cryogenic results are given

Single tube support post thermal analysis and test results

Cold mass structural supports used in prototype Superconducting Super Collider (SSC) 50 mm dipole magnets built at Fermilab and Brookhaven are adaptations of the design developed during the 40 mm design program at Fermilab. The design essentially consists of two composite tubes nested within each other as a means of maximizing the thermal path length. In addition it provides an ideal way to utilize materials best suited for the temperature range over which they must operate. Filament wound S-glass is used between 300K and 80K. Filament wound graphite fiber is used between 80K and 20K and between 20K and 4.5K. An alternate design for supports which uses a single composite tube has been developed at Fermilab and continues to be refined by the industrial contractors. The advantage of the new design is cost reduction due to a significantly simpler assembly and incorporation of many common parts. This report describes the thermal analysis and testing of a single composite tube support post whose function is identical to that of the current reentrant design

Design of the multilayer insulation system for the Superconducting Super Collider 50mm dipole cryostat

The development of the multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) 50 mm collider dipole cryostat is an ongoing extension of work conducted during the 40 mm cryostat program. While the basic design of the MLI system for the 50 mm cryostat resembles that of the 40 mm cryostat, results from measurements of MLI thermal performance below 80K have prompted a re-design of the MLI system for the 20K thermal radiation shield. Presented is the design of the MLI system for the 50 mm collider dipole cryostat, with discussion focusing on system performance, blanket geometry, cost-effective fabrication techniques, and built-in quality control measures that assure consistent thermal performance throughout the SSC accelerator. 16 refs., 8 figs., 2 tabs

Gate-tunable bandgap in bilayer graphene

The tight-binding model of bilayer graphene is used to find the gap between the conduction and valence bands, as a function of both the gate voltage and as the doping by donors or acceptors. The total Hartree energy is minimized and the equation for the gap is obtained. This equation for the ratio of the gap to the chemical potential is determined only by the screening constant. Thus the gap is strictly proportional to the gate voltage or the carrier concentration in the absence of donors or acceptors. In the opposite case, where the donors or acceptors are present, the gap demonstrates the asymmetrical behavior on the electron and hole sides of the gate bias. A comparison with experimental data obtained by Kuzmenko et al demonstrates the good agreement.Comment: 6 pages, 5 figure