Search results for "angle"
showing 10 items of 1921 documents
Entanglement dynamics in a spin star system
2009
The implementation of more and more efficient nanodevices exploitable in applicative contexts like for example quantum computers often requires a highly challenging miniaturizing process aimed at packing a huge number of point-like basic elements whose dynamics mimics indeed that of a qubit. Stimulated by such a requirement, over the last few years theoretical schemes using the language of the spin ½ system models have been investigated. The main reason is that besides the simple dynamical behaviour of each elementary constituent these Hamiltonian models do indeed capture basic ingredients of several physical situations differing one another mainly for the numerical values of some relevant …
Brewster angle microscopy and X-ray GID studies of morphology and crystal structure in monolayers of N-tetradecyl-γ,δ-dihydroxypentanoic acid amide
1997
First-order phase transitions from the low-density fluidlike phase to the condensed phase of monolayers of N-tetradecyl-γ,δ-dihydroxypentanoic acid amides at the air−water interface have been studied by π−A isotherms, Brewster angle microscopy (BAM), and synchrotron X-ray grazing incidence diffraction (GID). The thermodynamic differences between enantiomeric and racemic monolayers are too small to be measured. However, chiral discrimination is observable in the macroscopic domain morphology by BAM. The domains of the condensed phase grow dendritically. The characteristic shapes of domains of the pure S and R enantiomers are mirror images of each other. The domains of the racemic mixture are…
Crystal structure of meso-tetrakis(4-nitrophenyl)porphyrin nitrobenzene disolvate
2014
The porphyrin core of the title centrosymmetric compound, C44H26N8O8·2C6H5NO2, is approximately planar, the maximum deviation being 0.069 (3) Å. The planes of the benzene rings of the nitrophenyl substituents are almost perpendicular to the porphyrin mean plane, making dihedral angles of 73.89 (9) and 89.24 (9)°. The two pyrrole ring H atoms are equally disordered over the four pyrrole ring N atoms. In the crystal, weak C—H...O and C—H...N hydrogen bonds link the porphyrin molecules into a three-dimensional supramolecular network. The nitrobenzene solvent molecules are linked by weak C—H...O hydrogen bonds into supramolecular chains propagating along thea-axis direction.
Neutrino oscillation studies with IceCube-DeepCore
2016
IceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make…
How neutron scattering experiments can target the structure and dynamics of milk proteins?
2016
International audience; The powerful of neutron scattering techniques to characterize structure and dynamics of milk proteins is illustrated. Small angle neutron scattering and reflectivity are used to determine the structure and the interactions between milk proteins in solution, during gelation processes, or the protein structure at different interfaces. Experiments performed by inelastic and quasielastic neutron scattering allow one to observe the dynamics of water and proteins showing the major role of hydration on the dynamics of milk proteins.
Electrooptic beam deflection with latex
1988
The use of latex in electrooptic devices is proposed. The static non linearity coefficient is shown to be approximatively 200 times the optical one. The theory of a beam deflector is developed and an explicit expression is given for the deflection angle versus the physical parameters of the sample Utilisation de suspensions aqueuses de latex dans un dispositif electro-optique. On montre que le coefficient statique de non-linearite devrait etre 200 fois plus eleve que le coefficient optique. Application a un deflecteur optique
The third planet
1992
This paper examines the conceptions of planetary phenomena related to temperature change as held by primary school teacher trainees at the Department of Teacher Education of Jyvaskyla University. The data were collected by means of an essay test, supplemented by interviews. The results show that very few students have internalized these phenomena in accordance with present‐day scientific concepts. The significance of the Earth's sphericity seems particularly obscure. The influence of the angle of inclination of the Earth's axis is misunderstood. Similarly, temperature differences are erroneously attributed to the distance from the sun of the Earth or of a particular place. The students do n…
Améliorer l'école
2006
06003; "L'idée que l'école peut s'améliorer n'est pas qu'un acte de foi. Les recherches empiriques en sciences sociales mettent en évidence que l'école agit à partir d'un contexte social qui en détermine fortement les effets mais que, dans un contexte semblable, certaines approches pédagogiques, certains établissements, certains systèmes éducatifs produisent des effets différents : des élèves faibles moins faibles, des inégalités sociales moins élevées. La recherche en sciences sociales peut contribuer à cette amélioration de plusieurs façons, à la condition de se rappeler que la transformation radicale de l'école n'est pas possible, que les obstacles rencontrés par les élèves ne sont pas d…
La régulation de l'éducation en France et dans les pays anglo-saxons. Une comparaison
2004
The autonomy of the schools increased in most educational systems for the last twenty years. So, educational systems had to implement regulation policies in order to orient the action of the agents towards the nation's aims. While England and the United States implemented a regulation by results (incentives linked to school's or teacher's results), France relies on a regulation by process (incentives to implement ‘pedagogical forms' which are supposed to be relevant). These two policies are described, then they are confronted with regard to their internal coherence and tensions, with in mind the question of the French model being a viable one, able to offer an option to the anglo-saxon mode…
13C NMR Spin−Lattice Relaxation and Conformational Dynamics in a 1,4-Polybutadiene Melt
2001
We have performed molecular dynamics (MD) simulations of a melt of 1,4-polybutadiene (PBD, 1622 Da) over the temperature range 400-273 K. 13 C NMR spin-lattice relaxation times (T 1 ) and nuclear Overhauser enhancement (NOE) values have been measured from 357 to 272 K for 12 different resonances. The T 1 and NOE values obtained from simulation C-H vector P 2 (t) orientational autocorrelation functions were in good agreement with experiment over the entire temperature range. Analysis of conformational dynamics from MD simulations revealed that T 1 depends much less strongly on the local chain microstructure than does the mean conformational transition time. Spin-lattice relaxation for a give…