Narrow band quantitative and multivariate electroencephalogram analysis of peri-adolescent period

ABSTRACT: BACKGROUND: The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). RESULTS: The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0--20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. CONCLUSIONS: The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages.     

Many-component limit of the quantum Potts model

The q-component quantum Potts model is solved exactly in the limit q→∞. The resulting free energy and its first partial derivatives (order parameters) are shown to be identical to the corresponding mean-field expressions taken in the same limit.     

Pyrrolidine-2,3-dione, 1-allylpyrrolidine-2,3-dione and 1-ethoxypyrrolidine-2,3-dione

Authentic pyrrolidine-2,3-dione has been prepared by two different routes. It is shown that the material previously reported is actually a hydrolysis product, 4-amino-2-oxobutyric acid. 1-Allyl- and 1-ethoxypyrroli-dine-2,3-dione have been prepared as N-protected pyrrolidine-2,3-diones potentially useful in synthesis.     

Reflection equations and exactly solvable lattice spin models

Reflection equations are used to obtain families of commuting double-row transfer matrices for interaction-round-a-face (IRF) models with fixed and free boundary conditions. We illustrate our methods for the Andrews-Baxter-Forrester (ABF) models which areL-state models associated with the quantum groupU _q (su(2)) at a root of unity. We construct elliptic solutions to the reflection equations for the ABF models by a procedure which uses fusion to build the solutions starting from a trivial solution.Presented at the 5th International Colloquium on Quantum Groups: Quantum Groups and Integrable Systems, Prague, 20–22 June 1996.On leave from Department of Mathematics, University of Melbourne, Parkville, Victoria 3052, Australia.The authors thank Vladimir Rittenberg for his kind hospitality at Bonn. This work was supported by the Australian Research Council.     

Integrated microelectrode array and microfluidics for temperature clamp of sensory neurons in culture

A device for cell culture is presented that combines MEMS technology and liquid-phase photolithography to create a microfluidic chip that influences and records electrical cellular activity. A photopolymer channel network is formed on top of a multichannel microelectrode array. Preliminary results indicated successful local thermal control within microfluidic channels and control of lamina position over the electrode array. To demonstrate the biological application of such a device, adult dissociated dorsal root ganglion neurons with a subpopulation of thermally-sensitive cells are attached onto the electrode array. Using laminar flow, dynamic control of local temperature of the neural cells was achieved while maintaining a constant chemical culture medium. Recording the expected altered cellular activity confirms the success of the integrated device.     

Isomorphous replacement in nylon 6 by 4-aminomethylcyclohexanecarboxylic acid

It was desired to determine the effect of geometric configuration on the ability of 4-aminomethylcyclohexanecarboxylic acid (AMCC) to “isomorphously” replace ε-aminocaproic acid residues in nylon 6. However, we found that cis-AMCC isomerized to the more thermodynamically stable trans isomer during copolymerization with caprolactam (CL) and also during homopolymerization. A 20/80 cis/trans ratio of AMCC residues was found in the 50:50 copolyamides regardless of whether a high-cis (72/28) or high-trans (15/85) AMCC was used. Powder x-ray diagrams showed similar interplanar spacings for the copolyamides made from both high-cis and high-trans AMCC. The x-ray study also showed that the nylon 6 lattice can accommodate less than 30 mole-% AMCC residues before a new structure appears. DTA and TGA data of the CL:AMCC copolyamide showed that AMCC raised the melting point, T_g, T_c, and stability of nylon 6.     

Aromatic polyamides. XI. Effect of the halogen substitution on the thermal and flammability behavior of poly(1,4-phenylene terephthalamide)

This article concerns the synthesis and characterization of poly(1,4-phenylene terephthalamide) and halogenated derivatives thereof. It was found that the halogen substitution affected significantly the thermal characteristic and flame resistance of that polyamide. In a nonoxygen atmosphere two-step decomposition process for the halogenated, while only one-step for unsubstituted polyamides were observed. The results supported the previous suggestion, that in the case of the halogenated polyamides the char yield enhancement and the flame resistance improvement are associated with halogen release and ring-forming reactions during their pyrolysis.     

Thermal properties of wholly aromatic polyamides

Various wholly aromatic polyamides based on m-and p-phenylene diamines and isophthaloyl and terephthaloyl chloride have been synthesized and their thermal properties and oxygen index values have been studied. The effect of different substituents on the aromatic ring of the diamine have been explored by comparing their differential thermal analysis (DTA) and thermogravimetric analysis (TGA) behavior, their relative char yields at 700°C, and their oxygen indices. The ? Cl, ? NO₂, and ? OH substituted polyamides have been found to produce the highest char yields. The high char yields are probably associated with crosslinking occurring at high temperatures. Attempts at correlating char yield with oxygen index indicated enhancement for the chlorosubstituted aramids.