Quantized State Simulation of Spiking Neural Networks

In this work, we explore the usage of quantized state system (QSS) methods in the simulation of networks of spiking neurons. We compare the simulation results obtained by these discrete-event algorithms with the results of the discrete time methods in use by the neuroscience community. We found that the computational costs of the QSS methods grow almost linearly with the size of the network, while they grows at least quadratically in the discrete time algorithms. We show that this advantage is mainly due to the fact that QSS methods only perform calculations in the components of the system that experience activity. © 2012, Simulation Councils Inc. All rights reserved.Fil: Grinblat, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Ahumada, Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Kofman, Ernesto Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; Argentin

Sobre la implantación del ciclo de enseñanza básica

Fil: Ahumada, Guillermo. Universidad de Buenos Aires. Facultad de Derecho. Cátedra Finanzas y Derecho Financiero. Buenos Aires, ArgentinaFil: Beveraggi Allende, Walter. Universidad de Buenos Aires. Facultad de Derecho. Cátedra Economía Política. Buenos Aires, Argentin

Reaction between ferrocene-carboxaldehyde and dioxaphospholene: Characterization and crystal structures of an unexpected bisferrocenyldioxolane

CCDC 925532 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via http://www.ccdc.cam.as.uk/data_request/cifInternational audienceReacting an 1:1 stoichiometric molar ratio of ferrocenecarboxaldehyde and 2,2,2-trimethoxy-4,5-dimethyl-1,3,2-dioxaphospholene, neat, at room temperature for one week, leads to the diastereoselective formation of a bis-ferrocenyl 1,3-dioxolane complex 1-(4-methyl-2,5-diferrocenyl-1,3-dioxolan-4-yl)ethanone (1), in 30% isolated yield. The compound has been fully characterized by FT-IR, mono- and two-dimensional 1H and 13C NMR spectroscopy, elemental analysis, and cyclic voltammetry. Complex 1 has also been characterized by single crystal X-ray analysis

Synthesis, characterization and X-ray crystal structures of chiral ferrocene-containing β-diketones

CCDC 922490, 922491, and 922492 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.International audienceThree new chiral ferrocene-containing β-diketones have been synthesized by reacting 1-ferrocenyl ethanol with the corresponding 1,3-diketone reagent MeCOCH2COR (R = Me, 4-C6H4OMe, Fc; Fc = (η5-C5H5)Fe(η5-C5H4)), using cerium(IV) ammonium nitrate (CAN) mediated C-C bond formation. These compounds identified as 3-(1-ferrocenylethyl)-pentane-2,4-dione (1), 1-(4-methoxyphenyl)-2-(1-ferrocenylethyl)-butane-1,3-dione (2), and 1-ferrocenyl-2-(1-ferrocenylethyl)-butane-1,3-dione (3), have been isolated as air and thermally stable microcrystalline solids in 79, 63 and 44% yields, respectively. Compounds 2 and 3 were formed in 63:37 and 88:12 diastereomeric ratios, respectively. They have been fully characterized by elemental analyses, FT-IR spectra, mass spectrometry, and their complete assignments have been conducted using 2D NMR experiments. In addition, their molecular identity and geometry have been confirmed by single-crystal X-ray diffraction, and both solution and solid state measurements have shown that the three complexes exist solely as their diketo tautomers

Deacetylation of chiral ferrocenyl-containing β-diketones promoted by ethylene diamine: Spectroscopic and structural characterization of the fragmentation products

International audienceIt is well known that β-diketones react with primary amines, readily forming thecorresponding Schiff base derivatives. However, in the present case, the chiralferrocenyl-containing β-diketones, 3-(1-ferrocenylethyl)-pentane-2,4-dione (1a), 1-(4-methoxyphenyl)-2-(1-ferrocenylethyl)-butane-1,3-dione (1b), and 1-ferrocenyl-2-(1-ferrocenylethyl)-butane-1,3-dione (1c) react with ethylene diamine under acidicconditions in refluxing toluene to yield, unexpectedly, their deacetylated counterparts,3-ferrocenyl-butane-2-one (2a), 1-(4-methoxyphenyl)-3-ferrocenyl-butane-1-one (2b),and 1,3-bisferrocenyl-butane-2-one (2c), respectively. Such deacetylation reactions areaccompagned by the formation of 2-methyl-2-imidazoline. A reaction mechanisminvolving an intramolecular Michael addition followed by a retro-Mannichrearrangement is suggested. The ketones 2a-c are fully characterized by analytical andspectroscopic methods. Additionally, compounds 2a and 2c are authenticated by singlecrystal X-ray diffraction analysis. The electrochemical behaviour of the bimetalliccomplex 2c is also investigated

Potentiostatically Controlled Olefin Metathesis

A Ru(II) complex supported by an N-heterocyclic carbene annulated to a redox-active naphthoquinone (NQ) was interrogated using a range of potentiodynamic and potentiostatic electrochemical techniques. The complex exhibited two redox processes, one of which was attributed to the Ru(II)IRu(III) couple (E-1/2 = +1.10 V vs a saturated calomel electrode) and the other to the NQJNIQ(-) couple (E-1/2 = -0.62 V). Using potentiostatic coulometry or bulk electrolysis, the application of a fixed negative potential (-0.9S V) to electrodes placed in a dichloromethane solution containing the complex resulted in a reduction reaction. The complex was quantitatively reduced within minutes, as determined by coulometry, and subsequently oxidized to its initial, neutral form through the application of a relatively positive potential (+0.34 V) over similar periods of time. The interconversion process was found to be reversible and used to modulate a series of ring-closing metathesis and ring-opening metathesis polymerization reactions. While relatively high activities were observed when the neutral form of the catalyst was employed, the reaction rates were attenuated upon in situ, potentiostatic reduction. Toggling between relatively negative or positive potentials enabled the aforementioned olefin metathesis reactions to be switched between fast and slow states

Two substrates, three products: Reactions between ferrocene-carboxaldehyde and dioxaphospholene, characterization and crystal structures of oxygenated C3- and C4-chain-containing ferrocenes

CCDC 893249, 893248, and 893250 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.as.uk/data_request/cif.International audienceReactions of aldehydes RCHO with 2,2,2-trimethoxy-4,5-dimethyl-1,3,2-dioxaphospholene are known to form trimethylbiacetyl-aldehyde-phosphite adducts which upon methanolysis gave rise to the corresponding symmetrical 3-R-2,4-pentanediones (R = aryl, alkyl). Reactions between ferrocenecarboxaldehyde and the biacetyl-trimethylphosphite adduct, whatever the experimental conditions used, afforded three new oxygenated C3 and C4 side-chain containing ferrocenyl complexes, namely, 1-ferrocenyl-1,2-propanedione (1, Fc-C(O)C(O)CH3; Fc = (η5-C5H5)Fe(η5-C5H4)), 4-methoxy-4-ferrocenyl-3-hydroxy-3-methyl-2-butanone (2, Fc-CH(OCH3)C(CH3)(OH)C(O)CH3) as a single diastereoisomer, and the ferrocenyl enone 4-ferrocenyl-3-methyl-3-buten-2-one (3, Fc-CHdouble bond; length as m-dashC(CH3)C(O)CH3) with the enone portion adopting the s-trans conformation in the solid state. The compounds readily purified by silica gel packed column chromatography were isolated in 31-44% yields, and their constitution is in agreement with elemental analyses, IR and multinuclear NMR spectroscopy, and electrospray mass spectrometry. Their molecular identity and geometry have been confirmed by single-crystal X-ray diffraction

Extended evaluation of the UPM method for multiclass problems

Multiclass problems are usually of high technological value, but many classification methods are binary in origin. In the last years, several improved solutions based on the combination of simple classifiers were introduced. An interesting solution is based on creating a hierarchy of sub-problems by clustering prototypes of each one of the classes; there- fore the solution is heavily influenced by the label’s information. In this work we analyze a new strategy to solve multiclass problems that makes more use of spatial information than other methods. We construct a hier- archy of subproblems, but opposite to previous developments, based only on spatial information and not using a single prototype for each class. We evaluate the use of different clustering methods (either agglomera- tive or divisive) for this task and also the use two different classifiers (linear SVM and FDA–GenRidge) for each sub-problem (if needed, be- cause in several cases the clustering method directly gives a subset with samples of a single class). We compare the new method with several pre- vious approaches, finding promising results. The good performance of our approach is virtually independent of the classifier coupled to it, which suggest that it success is primarily related to the use of an appropriate clustering strategy.Sociedad Argentina de Informática e Investigación Operativ

Modelado de un Reactor Tubular Horizontal con Condensación, en Estado Estacionario

Se propone una alternativa de modelado de un reactor tubular horizontal de carcasa y tubo, donde la alimentación es completamente gaseosa. Durante el enfriamiento de esta corriente gaseosa, el reactor se modeló como un PFR (Plug Flow Reactor) con servicio de enfriamiento en contracorriente, verificando la disminución de la temperatura con respecto al punto rocío de la mezcla, de modo que permita detectar la sección donde comienza la condensación. A partir de la formación de la fase líquida, la corriente de proceso avanza con un frente bifásico L–V en equilibrio y con reacciones químicas en ambas fases. Una secuencia de múltiples CSTR (Continuous Stirred Tank Reactor) en serie con enfriamiento y en estado estacionario, se propone como modelado del condensador en la etapa de flujo bifásico. La aplicación de este modelo a un equipo de similares características, involucrado en el proceso de producción de ácido nítrico que dispone una empresa en Argentina, permitió la validación del modelado que se propone, a través de la constatación de los valores establecidos por el proveedor de su tecnología. El modelo propuesto predice satisfactoriamente las corrientes resultantes de una operación con las características descriptas