230 research outputs found
The sparse Blume-Emery-Griffiths model of associative memories
We analyze the Blume-Emery-Griffiths (BEG) associative memory with sparse
patterns and at zero temperature. We give bounds on its storage capacity
provided that we want the stored patterns to be fixed points of the retrieval
dynamics. We compare our results to that of other models of sparse neural
networks and show that the BEG model has a superior performance compared to
them.Comment: 23 p
Gradation of Algebras of Curves by the Winding Number
We construct a new grading on the Goldman Lie algebra of a closed oriented
surface by the winding number. This grading induces a grading on the HOMFLY-PT
skein algebra and related algebras. Our work supports the conjectures of B.
Cooper and P. SamuelsonComment: Changed acknowledgments and Definition 2.
Full spectroscopic characterization of an hydrolytically stable and colored Ti(IV)-precursor in solution
Study of Xenon Mobility in the Two Forms of MIL-53(Al) Using Solid-State NMR Spectroscopy
The
Al-based metalâorganic framework (MOF) MIL-53Â(Al) exhibits
a structural transition between a large-pore (<i>lp</i>)
form and a narrow-pore (<i>np</i>) one. Such change is induced
by temperature, external pressure, or the adsorption of guest molecules. <sup>129</sup>Xe solid-state NMR experiments under static and magic-angle
spinning (MAS) conditions have been used to study the <i>lp</i>â<i>np</i> transition in MIL-53Â(Al) initially loaded
with xenon gas under a pressure of 5 Ă 10<sup>4</sup> Pa (at
room temperature). The conversion of the <i>lp</i> form
into the <i>np</i> one when the temperature decreases from
327 to 237 K and the reopening of the pores below 230 K are then observed.
Furthermore, <sup>1</sup>H â <sup>129</sup>Xe cross-polarization
under MAS (CPMAS) experiments demonstrate the possibility to observe
the <i>np</i> phase at <i>T</i> †230 K,
while the <i>lp</i> one is unseen because the xenon residence
time is too short for successful cross-polarization transfer. Moreover,
even for the <i>np</i> phase at 199 K, the xenon atoms still
exhibit significant motion on time scale faster than a few milliseconds.
We prove the exchange of Xe atoms between the <i>lp</i> and <i>np</i> forms at room temperature with the two-dimensional (2D) <sup>129</sup>Xe EXchange SpectroscopY (EXSY) NMR method. Using <sup>129</sup>Xe selective inversion recovery (SIR) experiments, the rate for this
exchange has been measured at 43 ± 6 s<sup>â1</sup>
Clusters et polymÚres de coordination: Spéciation et transfert de radionucléides
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Installation EPICUR : Les MOFs (Metal-Organic Frameworks) : Des materiaux innovants et rĂ©sistants pour lâindustrie nuclĂ©aire
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Utilisation de matĂ©riaux poreux pour la capture et dĂ©sactivation dâagents toxiques et pathogĂšnes
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