Simultaneous speech coding and de-noising in a dictionary based quantized CS framework

Speech compression or speech coding is inevitable for effective communication of speech signals in resource limited scenarios and researcher’s have been working on achieving lower and lower transmission bit rates (BR) without much compromise on the quality of speech. Medium BR hybrid speech coding schemes have gained much interest in the recent years with most of them based on CELP, the basic medium bit-rate coding scheme. In this work, we provide an insight to the capabilities of compressive sensing (CS) in speech processing and propose a novel idea in the quantized framework. Three major aspects demonstrated in this paper are (1) Inherent de-noising of noisy speech by the CS based coder along with compression (2) Quantization of CS measurements to achieve medium transmission bit-rates and (3) Enhancement of quality and compression performance of the coder with better sparse representations of speech using dictionaries. The results indicate that the proposed scheme offers better compression in comparison with basic Gaussian codebook CELP. The CS scheme has the added advantage of inherent noise suppression and provides more robustness to background noise in comparison with parameter extraction based medium bit-rate speech coding systems.     

Higher order spectra analysis of breast thermograms for the automated identification of breast cancer

Breast cancer is a leading cancer affecting women worldwide. Mammography is a scanning procedure involvingX‐rays of the breast. It causes discomfort and may cause high incidence of false negatives. Breast thermography is a new screening method of breast that helps in the early detection of cancer. It is a non‐invasive imaging procedure that captures the infrared heat radiating off from the breast surface using an infrared camera. The main objective of this work is to evaluate the use of higher order spectral features extracted from thermograms in classifying normal and abnormal thermograms. For this purpose, we extracted five higher order spectral features and used them in a feed‐forward artificial neural network (ANN) classifier and a support vector machine (SVM). Fifty thermograms (25 each of normal and abnormal) were used for analysis.SVM presented a good sensitivity of 76% and specificity of 84%, and theANN classifier demonstrated higher values of sensitivity (92%) and specificity (88%). The proposed system, therefore, shows great promise in automatic classification of normal and abnormal breast thermograms without the need for subjective interpretation.     

ThyroScreen system: high resolution ultrasound thyroid image characterization into benign and malignant classes using novel combination of texture and discrete wavelet transform

Using right equipment and well trained personnel, ultrasound of the neck can detect a large number of non-palpable thyroid nodules. However, this technique often suffers from subjective interpretations and poor accuracy in the differential diagnosis of malignant and benign thyroid lesions. Therefore, we developed an automated identification system based on knowledge representation techniques for characterizing the intra-nodular vascularization of thyroid lesions. Twenty nodules (10 benign and 10 malignant), taken from 3-D high resolution ultrasound (HRUS) images were used for this work. Malignancy was confirmed using fine needle aspiration biopsy and subsequent histological studies. A combination of discrete wavelet transformation (DWT) and texture algorithms were used to extract relevant features from the thyroid images. These features were fed to different configurations of AdaBoost classifier. The performance of these configurations was compared using receiver operating characteristic (ROC) curves. Our results show that the combination of texture features and DWT features presented an accuracy value higher than that reported in the literature. Among the different classifier setups, the perceptron based AdaBoost yielded very good result and the area under the ROC curve was 1 and classification accuracy, sensitivity and specificity were 100%. Finally, we have composed an Integrated Index called thyroid malignancy index (TMI) made up of these DWT and texture features, to facilitate distinguishing and diagnosing benign or malignant nodules using just one index or number. This index would help the clinicians in more quantitative assessment of the thyroid nodules.     

Automated classification of patients with coronary artery disease using grayscale features from left ventricle echocardiographic images

Coronary Artery Disease (CAD), caused by the buildup of plaque on the inside of the coronary arteries, has a high mortality rate. To efficiently detect this condition from echocardiography images, with lesser inter-observer variability and visual interpretation errors, computer based data mining techniques may be exploited. We have developed and presented one such technique in this paper for the classification of normal and CAD affected cases. A multitude of grayscale features (fractal dimension, entropies based on the higher order spectra, features based on image texture and local binary patterns, and wavelet based features) were extracted from echocardiography images belonging to a huge database of 400 normal cases and 400 CAD patients. Only the features that had good discriminating capability were selected using t-test. Several combinations of the resultant significant features were used to evaluate many supervised classifiers to find the combination that presents a good accuracy. We observed that the Gaussian Mixture Model (GMM) classifier trained with a feature subset made up of nine significant features presented the highest accuracy, sensitivity, specificity, and positive predictive value of 100%. We have also developed a novel, highly discriminative HeartIndex, which is a single number that is calculated from the combination of the features, in order to objectively classify the images from either of the two classes. Such an index allows for an easier implementation of the technique for automated CAD detection in the computers in hospitals and clinics.     

High surface area sol–gel nano silica as a novel drug carrier substrate for sustained drug release

Among various carrier materials for drug delivery, silica has been found to be significant for loading and sustained release of the drug. In the present study, the antibiotic gentamicin was incorporated in various amounts on to a silica matrix, using a sol–gel subcritical drying route. Crack free silica rods with a length of 1–1.5 cm, diameter of 0.5 cm and density of 1.35 g/cm³ incorporated with gentamicin were obtained. The incorporation of gentamicin into the silica matrix was revealed by FTIR. The adsorption–desorption isotherms and pore size distribution were studied in detail. The drug elution patterns were analysed and show a biphasic mode of release. After the initial burst release, a constant release pattern is observed. A release value above the minimum inhibitory concentration (MIC) is always maintained. The amount of drug released is higher than that of many other bioactive ceramic materials. An attempt has been made to correlate the functional properties with the porosity features.     

Effect of halogen substitution on azo-naphthol dye based poly(alkyloxymethacrylate)s and their Z-scan measurements

A series of photo addressable polymers bearing azo-naphthol moiety in the polymer side chain containing polymethacrylate backbone were synthesized for NLO applications. Various halogen atoms were substituted in the para position of the side chain azobenzene, and the effects of the substituents were investigated. The polymers were characterized by UV, FT-IR, ¹H-NMR and ¹³C-NMR spectroscopy. The photoisomerization property of all the polymers shows a clear dependence on the size of the halogen, indicating the rate of the switching time in the increasing order of F > Cl > Br > I. The glass transition temperature and thermal stability of the polymers were analyzed by DSC and TGA respectively. The third order nonlinear optical properties of the polymer film were measured by the Z-scan technique using Ar-ion laser and exhibited negative optical nonlinearity. The results revealed that these polymers possess potential applications in nonlinear optics and the value of nonlinear susceptibility for the iodine substituted polymer is higher than the other halogen substituted polymers chosen in the study.     

A comparative study of radioprotection by Ocimum flavonoids and synthetic aminothiol protectors in the mouse

The radioprotective effects of two flavonoids, orientin (Ot) and vicenin (Vc), obtained from the leaves of Ocimum sanctum, and the synthetic compounds WR-2721 and MPG (2-mercaptopropionyl glycine) have been compared by examining chromosome aberration in cells of bone marrow in irradiated mice. Healthy adult Swiss mice were injected intraperitoneally (i.p.) with 50 micrograms kg-1 body weight of Ot or Vc; 20 mg kg-1 of MPG; 150 mg kg-1 of WR-2721 or double distilled water (DDW). They were exposed to whole body irradiation of 2.0 Gy gamma radiation 30 min later. After 24 h, chromosomal aberrations were studied in the bone marrow of the femur by routine metaphase preparation after colchicine treatment. Radiation (2 Gy) increased the number of aberrant cells from less than 1% in controls to almost 20%. Pre-treatment with all the protective compounds resulted in a significant reduction in the percentage of aberrant metaphases as well as in the different types of aberration scored. Vc produced the maximum reduction in percent aberrant cells while MPG was the least effective; Ot and WR-2721 showed an almost similar effect. However, WR-2721 was the most effective against reduction of complex an almost similar effect. However, WR-2721 was the most effective against reduction of complex aberrations, followed by Vc. Neither flavonoids had any systemic toxicity, even at 200 mg kg-1 body weight. Considering the low dose needed for protection and the high margin between the effective and toxic doses, the ocimum flavonoids may be promising for human radiation protection.     

Synthesis and characteristic studies on pure and nano silver oxide-doped polypyrrole for supercapacitor application

Journal of Materials Science: Materials in Electronics - Polypyrrole (PPy) has higher conductivity than other conducting polymers. As the cost is lower than carbon-based electrodes, PPy is...     

Optical properties of Eu<Superscript>3+</Superscript> activated SrLa<Subscript>2</Subscript>O<Subscript>4</Subscript> red-emitting phosphors for WLED applications

The SrLa_2?xO₄:xEu³⁺ phosphors are synthesized through high-temperature solid-state reaction method at 1473 K with various doping concentration. Their phase structures, absorption spectra, and luminescence properties are investigated by X-ray diffraction (XRD), UV–Vis spectrophotometer and photoluminescence spectrometry. The intense absorption of SrLa_2?xO₄:xEu³⁺ phosphors have occurred around 400 nm. The prominent luminescence spectra of the prepared phosphors exhibited bright red emission at 626 nm. The doping concentration 0.12 mol% of Eu³⁺ is shown to be optimal for prominent red emission and chromaticity coordinates are x?=?0.692, y?=?0.3072. Considering the high colour purity and appropriate emission intensity of Eu³⁺ doped SrLa₂O₄ can be used as red phosphors for white light emitting diodes (WLEDs).