Statistical modeling of speech Poincaré sections in combination of frequency analysis to improve speech recognition performance

This paper introduces a combinational feature extraction approach to improve speech recognition systems. The main idea is to simultaneously benefit from some features obtained from Poincare? section applied to speech reconstructed phase space (RPS) and typical Mel frequency cepstral coefficients (MFCCs) which have a proved role in speech recognition field. With an appropriate dimension, the reconstructed phase space of speech signal is assured to be topologically equivalent to the dynamics of the speech production system, and could therefore include information that may be absent in linear analysis approaches. Moreover, complicated systems such as speech production system can present cyclic and oscillatory patterns and Poincare? sections could be used as an effective tool in analysis of such trajectories. In this research, a statistical modeling approach based on Gaussian mixture models (GMMs) is applied to Poincare? sections of speech RPS. A final pruned feature set is obtained by applying an efficient feature selection approach to the combination of the parameters of the GMM model and MFCC-based features. A hidden Markov model-based speech recognition system and TIMIT speech database are used to evaluate the performance of the proposed feature set by conducting isolated and continuous speech recognition experiments. By the proposed feature set, 5.7% absolute isolated phoneme recognition improvement is obtained against only MFCC-based features.     

Spin‐1 Bose Hubbard Model with Nearest Neighbour Extended Interaction

A spinor () Bose gas is studied in presence of a density‐density interaction through a mean field approach and a perturbation theory for either sign of the spin dependent interaction, namely the antiferromagnetic (AF) and the ferromagnetic cases. In the AF case, the charge density wave (CDW) phase appears to be sandwiched between the Mott insulating (MI) and the supersolid phases for small values of the extended interaction strength. But the CDW phase completely occupies the MI lobe when the extended interaction strength is larger than a certain critical value related to the width of the MI lobes and hence opens up the possibilities of spin singlet and nematic CDW insulating phases. In the ferromagnetic case, the phase diagram shows similar features as that of the AF case and are in complete agreement with a spin‐0 Bose gas. The perturbation expansion calculations nicely corroborate the mean field phase results in both these cases. Further, we extend our calculations in presence of a harmonic confinement and obtained the momentum distribution profile that is related to the absorption spectra in order to distinguish between different phases.     

First-derivative spectrophotometric determination of salicylic acid in aspirin

Salicyclic acid has been determined in aspirin powder and tablets by first-derivative spectrophotometry at 316 nm with base-line correction, with a coefficient of variation less than 1%.     

The use of the first-derivative curves of absorption spectra in quantitative analysis

The first-derivative curves of u.v.—visible spectra (ΔE/Δλ ) are useful in quantitative analysis. A base-line technique and its algebraic version are reported for (i) the correction of quadratic irrelevant absorption, and (ii) the determination of a substance in the presence of another with overlapping spectra. The method is illustrated by the determination of atropine sulphate in the presence of phenyl-mercury(II) nitrate. The results obtained suggest that the method warrants careful study over a wide field of applications.     

Spiroquinazoline support studies: methods for the preparation of imidazoloindolines from oxindoles

Two methods for the annulation of glycine to the 1 and 2 positions of oxindoles are described. The first method involves introduction of an α-azidoacetyl group on the oxindole nitrogen followed by an intramolecular Staudinger reaction to complete the annulation. The second method involves acylation of the oxindole nitrogen with an N-Cbz-glycine derivative followed by reduction of the oxindole carbonyl group and subsequent cyclization to provide an imidazoloindoline.     

Fresh evidence for proposed zwitterionic intermediates

A new selective and sensitive method for the detection of aliphatic amines has been developed with chloride-form anion-exchange resins and 2,4-dinitrotoluene. The reaction with tertiary amines can only be explained in terms of hitherto postulated zwitterionic intermediates.     

Highly Selective and Sensitive Triiodide PVC‐Membrane Electrode Based on a New Charge‐Transfer Complex of Bis(2,4‐Dimethoxybenzaldehyde)butane‐2,3‐Dihydrazone with Iodine

In this work, a highly selective membrane triiodide sensor based on a new charge‐transfer complex of bis(2,4‐dimethoxybenzaldehyde)butane‐2,3‐dihydrazone with iodine (Iodide Charge Transfer complex: ICT) as membrane carrier is introduced. The influences of five different solvent mediators on sensitivity and selectivity of the proposed sensor were considered. The best performance was obtained with the membrane composition containing 30% poly (vinyl chloride), 63% DBP, 5% ICT and 2% HTAB. The electrode shows a Nernstian behavior over a very wide triiodide ion concentration range (1.0 × 10^?7‐1.0 × 10^?2 M), and a detection limit value of 8.0 × 10^?8 M. The effect of pH on the potentiometric response of the sensor was also studied, and it was found that the response of the electrode is independent of the pH of the solution in the pH range of 4.0–10. The proposed sensor has a very fast response time (< 12 s), and good selectivities relative to a wide variety of common inorganic and organic anions, including iodide, acetate, bromide, chloride, fluoride, nitrite, nitrate, sulfite, sulfate, cyanide and thiocyanate. In fact the selectivity behavior of the proposed triiodide ion‐selective electrode shows great improvements compared to the previously reported electrodes for triiodide ion. The proposed membrane sensor can be used for at least 6 months without any divergence in the potentials. The electrode was successfully applied as an indicator electrode in the titration of triiodide with thiosulfate ion.     

Determination of nanomolar concentrations of phosphate in freshwaters using flow injection with luminol chemiluminescence detection

A simple and rapid flow injection (FI) method is reported for the determination of phosphate (as molybdate reactive P) in freshwaters based on luminol chemiluminescence (CL) detection. The molybdophosphoric heteropoly acid formed by phosphate and ammonium molybdate in acidic conditions generated chemiluminescence emission via the oxidation of luminol. The detection limit (3× standard deviation of blank) was 0.03 μg P l⁻¹ (1.0 nM), with a sample throughput of 180 h⁻¹. The calibration graph was linear over the range 0.032–3.26 μg P l⁻¹ (r²=0.9880) with relative standard deviations (n=4) in the range 1.2–4.7%. Interfering cations (Ca(II), Mg(II), Ni(II), Zn(II), Cu(II), Co(II), Fe(II) and Fe(III)) were removed by passing the sample through an in-line iminodiacetate chelating column. Silicate interference (at 5 mg Si l⁻¹) was effectively masked by the addition of tartaric acid and other common anions (Cl⁻, SO₄²⁻, HCO₃⁻, NO₃⁻ and NO₂⁻) did not interfere at their maximum admissible concentrations in freshwaters. The method was applied to freshwater samples and the results (26.1±1.1–62.0±0.4 μg P l⁻¹) were not significantly different (P=0.05) from results obtained using a segmented flow analyser method with spectrophotometric detection (24.4±4.45–84.0±16.0 μg P l⁻¹).     

Determination,by dynamic surface-tension analysis,of the molar mass of proteins denatured in guanidine thiocyanate

A drop-based dynamic surface-tension detector (DSTD) has been used to study the dynamic surface tension behavior of proteins denatured in guanidine thiocyanate (GndSCN). The dynamic surface tension at the air–liquid interface is obtained by measuring the internal pressure of drops that grow and detach at a specified rate. In the method the sample of interest is injected and subsequently flows to the DSTD-sensing capillary tip. For this work, a novel DSTD calibration procedure utilizing two distinct mobile phases is applied. Here, the mobile phases are aqueous with different constituents, for example GndSCN and phosphate buffer, either added or omitted. The dual-mobile phase calibration procedure gives the analyst the capability of making protein measurements in a GndSCN–phosphate buffer mobile phase, while measuring a calibration standard in another mobile phase, such as water, in which the surface tension of the calibration standard is readily available. Results are presented with drop volumes of either 2 L (i.e. 2-s drops) or 7 L (i.e. 7-s drops) for proteins varying in molar mass from 12,000 to 330,000 g mol^–1. We demonstrate that the DSTD can be used to determine the molar mass of proteins denatured in GndSCN. The method applies a regime where the denatured protein is detected by surface-active properties, and selectivity with regard to molar mass is contained in the dynamic component of the DSTD signal. The dynamic surface pressure signals of the denatured proteins suggest that diffusion plays a large role in the kinetics of the surface activity. The limit of detection for the denatured proteins studied ranged from 3 mg L^–1 to 14 mg L^–1. The DSTD, coupled with the novel dual-mobile phase calibration procedure, can be used to investigate the fundamental properties of proteins. Insight into the behavior at the air–liquid interface for native and denatured proteins is achieved; this is a novel tool for studying protein denaturation, complementary to other common approaches such as spectroscopy and calorimetry. Furthermore, the reported method could be widely applied to the study of effects on the interfacial properties of proteins after a variety of chemical and physical modifications that are possible with the dual-mobile phase calibration procedure.