Two structural adaptations for regulating transmitter release at lobster neuromuscular synapses

The distal accessory flexor muscle (DAFM) in the lobster (Homarus americanus) walking leg consists of 5 muscle fiber bundles. All five bundles, one proximal, one distal, and 3 medial, are innervated by one excitatory and one inhibitory motor neuron. Both neurons release more transmitter on the distal bundle than on the proximal bundle. The aim of our studies was to investigate the structural basis of this differentiation. Thin sections cut at 50 microns intervals showed a similar number of excitatory synapses on the two bundles. Freeze-fracture views of excitatory synapses showed that synapse size, active zone number per synapse, and intramembrane particle density in the postsynaptic membrane are similar proximally and distally. Active zones at synapses on the distal bundle are larger and contain about 50% more large intramembrane particles, which are thought to include the voltage-gated Ca2+ channels that couple the action potential to transmitter release, than their counterparts on the most proximal bundle. This difference in channel number appears to produce a disproportionate increase in the probability of transmitter release sufficient to account for most of the proximal-distal disparity in the amplitude of the excitatory postsynaptic potential. In contrast, staining the inhibitor for antibodies to the inhibitory neurotransmitter, GABA, showed that it forms more varicosities on the distal bundle than on the proximal bundle. Because most of the synapses are located in the varicosities, differences in synapse number likely regulate the proximal-distal disparity in the amount of inhibitory transmitter released. Therefore, the regional differentiation in the amount of transmitter released in the DAFM appears to be based on two distinct mechanisms. In the inhibitor, transmitter release appears to be regulated differentially by differences in synapse number. In the excitor, transmitter release appears to be regulated differentially from a similar number of synapses by differences in active zone structure.     

Yield optimization for complex reactor systems

For complex reactions, the choice of reactor type is important for attaining optimum product yields. Strategies for specifying reactor types have beenIn this paper, product yield in a Van de Vusse reaction scheme has been studied for a wide range of the rate constants, in a reactor system consisting     

Comparative Study of the Different Variants of the DV-Hop Based Node Localization Algorithms for Wireless Sensor Networks

Wireless Personal Communications - Node localization is one of the essential services where sensor nodes in the wireless sensor network collaborate to provide location information of sensor nodes...     

Virtual modeling of an ankle foot orthosis for correction of foot abnormality

Clubfoot is a challenging structural foot abnormality in babies and generally occurs at birth or during childhood. Due to this the abnormal posturing of the foot causes the babies to turn the ankle inward and walk along the outside edges of the foot. In medical science it is known as “congenital talipes equino varus” (CTEV). Computer modeling of prosthesis and orthosis is a perspective method for optimal design and gait is a terminology related to walking patterns of human subject.     

Development of simulated emotion speech database for excitation source analysis

The work presented in this paper is focused on the development of a simulated emotion database particularly for the excitation source analysis. The presence of simultaneous electroglottogram (EGG) recordings for each emotion utterance helps to accurately analyze the variations in the source parameters according to different emotions. The work presented in this paper describes the development of comparatively large simulated emotion database for three emotions (Anger, Happy and Sad) along with neutrally spoken utterances in three languages (Tamil, Malayalam and Indian English). Emotion utterances in each language are recorded from 10 speakers in multiple sessions (Tamil and Malayalam). Unlike the existing simulated emotion databases, instead of emotionally neutral utterances, emotionally biased utterances are used for recording. Based on the emotion recognition experiments, the emotions elicited from emotionally biased utterances are found to show more emotion discrimination as compared to emotionally neutral utterances. Also, based on the comparative experimental analysis, the speech and EGG utterances of the proposed simulated emotion database are found to preserve the general trend in the excitation source characteristics (instantaneous F0 and strength of excitation parameters) for different emotions as that of the classical German emotion speech-EGG database (EmoDb). Finally, the emotion recognition rates obtained for the proposed speech-EGG emotion database using the conventional mel frequency cepstral coefficients and Gaussian mixture model based emotion recognition system, are found to be comparable with that of the existing German (EmoDb) and IITKGP-SESC Telugu speech emotion databases.     

Expressive speech synthesis: a review

The objective of the present work is to provide a detailed review of expressive speech synthesis (ESS). Among various approaches for ESS, the present paper focuses the development of ESS systems by explicit control. In this approach, the ESS is achieved by modifying the parameters of the neutral speech which is synthesized from the text. The present paper reviews the works addressing various issues related to the development of ESS systems by explicit control. The review provided in this paper include, review of the various approaches for text to speech synthesis, various studies on the analysis and estimation of expressive parameters and various studies on methods to incorporate expressive parameters. Finally the review is concluded by mentioning the scope of future work for ESS by explicit control.     

Some Thermodynamic Aspects of the Oxides of Chromium

To understand Cr emissions from slag melts to a vapor phase, an assessment of the stabilities of the chromium oxides at high temperatures has been carried out. The objective of the present study is to present a set of consistent data corresponding to the thermodynamic properties of the oxides of chromium, with special reference to the emission of hexavalent chromium from slags. In the current work, critical analysis of the experimental data available and a third analysis in the case of Cr₂O₃ have been carried out. Commercial databases, Fact Sage and ThermoCalc along with NIST-JANAF Thermochemical Tables, have been used for the analysis and comparisons of the results that are presented. The significant discrepancies in the available data have been pointed out. The data from NIST-JANAF Thermochemical Tables have been found to provide a set of consistent data for the various chromium oxides. An Ellingham diagram and the equations for the ΔG° (standard Gibbs free energy change) of formation of CrO _x have been proposed. The present analysis shows that CrO₃(g) is likely to be emitted from slag melts at high oxygen partial pressures.     

Significantly high electromagnetic shielding effectiveness in polypyrrole synthesized by eco-friendly and cost-effective technique

A facile and eco-friendly synthesis of polypyrrole from monomer pyrrole using nominal amount of ferric chloride hexahydrate (FeCl₃.6H₂O) oxidant in aqueous solution by chemically oxidative polymerization method has been reported. The use of aqueous solvent and ferric chloride hexahydrate salt in polypyrrole synthesis have an eco-friendly route favorable for the production of polypyrrole in large quantities. The synthesized polypyrrole samples exhibit good electrical conductivity (2 S/cm) and yield of 80% for reaction time of 8 hr at 5°C. Quality and properties of polypyrrole samples have been thoroughly investigated with varying reaction time and temperature while other synthesis parameters like molar ratio of oxidant to monomer, oxidant concentration, and solvent were kept constant. X-ray diffraction analysis of polypyrrole with a shorter reaction time shows the presence of iron oxide (Fe₂O₃) peaks. The complete reaction may not occur at shorter reaction times due to which residual ferric ions converted into Fe₂O₃. X-ray photoelectron spectroscopy measurement of polypyrrole also confirms the formation of Fe₂O₃. Appropriate selection of reaction time and temperature produced pure phase polypyrrole with high yield and good conductivity. Synthesized polypyrrole by our eco-friendly and cost-effective technique exhibits prominent electromagnetic shielding effectiveness value of 30 dB in the X-band (8–12 GHz).