The visibility based Tapered Gridded Estimator (TGE) for the redshifted 21-cm power spectrum

We present the improved visibility based Tapered Gridded Estimator (TGE) for the power spectrum of the diffuse sky signal. The visibilities are gridded to reduce the computation, and tapered through a convolution to suppress the contribution from the outer regions of the telescope's field of view. The TGE also internally estimates the noise bias, and subtracts this out to give an unbiased estimate of the power spectrum. An earlier version of the 2D TGE for the angular power spectrum $C_{\ell}$ is improved and then extended to obtain the 3D TGE for the power spectrum $P({\bf k})$ of the 21-cm brightness temperature fluctuations. Analytic formulas are also presented for predicting the variance of the binned power spectrum. The estimator and its variance predictions are validated using simulations of $150 \, {\rm MHz}$ GMRT observations. We find that the estimator accurately recovers the input model for the 1D Spherical Power Spectrum $P(k)$ and the 2D Cylindrical Power Spectrum $P(k_\perp,k_\parallel)$, and the predicted variance is also in reasonably good agreement with the simulations.Comment: 19 pages, 13 figures. Accepted for publication in MNRAS. The definitive version will be available at http://mnrasl.oxfordjournals.org

Effect of dust and anthropogenic aerosols on columnar aerosol optical properties over Darjeeling (2200 m asl), Eastern Himalayas, India

Background: The loading of atmospheric particulate matter (aerosol) in the eastern Himalaya is mainly regulated by the locally generated anthropogenic aerosols from the biomass burning and by the aerosols transported from the distance sources. These different types of aerosol loading not only affect the aerosol chemistry but also produce consequent signature on the radiative properties of aerosol. Methodology/Principal Findings: An extensive study has been made to study the seasonal variations in aerosol components of fine and coarse mode aerosols and black carbon along with the simultaneous measurements of aerosol optical depth on clear sky days over Darjeeling, a high altitude station (2200 masl) at eastern Himalayas during the year 2008. We observed a heavy loading of fine mode dust component (Ca2+) during pre-monsoon (Apr - May) which was higher by 162 than its annual mean whereas during winter (Dec - Feb), the loading of anthropogenic aerosol components mainly from biomass burning (fine mode SO4 2- and black carbon) were higher (76 for black carbon and 96 for fine mode SO4 2-) from their annual means. These high increases in dust aerosols during pre-monsoon and anthropogenic aerosols during winter enhanced the aerosol optical depth by 25 and 40, respectively. We observed that for every 1 increase in anthropogenic aerosols, AOD increased by 0.55 during winter whereas for every 1 increase in dust aerosols, AOD increased by 0.46 during pre-monsoon. Conclusion/Significance: The natural dust transport process (during pre-monsoon) plays as important a role in the radiation effects as the anthropogenic biomass burning (during winter) and their differential effects (rate of increase of the AOD with that of the aerosol concentration) are also very similar. This should be taken into account in proper modeling of the atmospheric environment over eastern Himalayas

Exploring strategies for classification of external stimuli using statistical features of the plant electrical response

This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this record.Plants sense their environment by producing electrical signals which in essence represent changes in underlying physiological processes. These electrical signals, when monitored, show both stochastic and deterministic dynamics. In this paper, we compute 11 statistical features from the raw non-stationary plant electrical signal time series to classify the stimulus applied (causing the electrical signal). By using different discriminant analysis-based classification techniques, we successfully establish that there is enough information in the raw electrical signal to classify the stimuli. In the process, we also propose two standard features which consistently give good classification results for three types of stimuli--sodium chloride (NaCl), sulfuric acid (H₂SO₄) and ozone (O₃). This may facilitate reduction in the complexity involved in computing all the features for online classification of similar external stimuli in future.The work reported in this paper was supported by project PLants Employed As SEnsor Devices (PLEASED), EC grant agreement number 296582

Forward and Inverse Modelling Approaches for Prediction of Light Stimulus from Electrophysiological Response in Plants

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.In this paper, system identification approach has been adopted to develop a novel dynamical model for describing the relationship between light as an environmental stimulus and the electrical response as the measured output for a bay leaf (Laurus nobilis) plant. More specifically, the target is to predict the characteristics of the input light stimulus (in terms of on-off timing, duration and intensity) from the measured electrical response - leading to an inverse problem. We explored two major classes of system estimators to develop dynamical models - linear and nonlinear - and their several variants for establishing a forward and also an inverse relationship between the light stimulus and plant electrical response. The best class of models are given by the Nonlinear Hammerstein-Wiener (NLHW) estimator showing good data fitting results over other linear and nonlinear estimators in a statistical sense. Consequently, a few set of models using different functional variants of NLHW has been developed and their accuracy in detecting the on-off timing and intensity of the input light stimulus are compared for 19 independent plant datasets (including 2 additional species viz. Zamioculcas zamiifolia and Cucumis sativus) under similar experimental scenario.The work reported in this paper was supported by project PLants Employed As SEnsor Devices (PLEASED), EC grant agreement number 296582

Drift Removal in Plant Electrical Signals via IIR Filtering Using Wavelet Energy

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Plant electrical signals often contains low frequency drifts with or without the application of external stimuli. Quantification of the randomness in plant signals in a stimulus-specific way is hindered because the knowledge of vital frequency information in the actual biological response is not known yet. Here we design an optimum Infinite Impulse Response (IIR) filter which removes the low frequency drifts and preserves the frequency spectrum corresponding to the random component of the unstimulated plant signals by bringing the bias due to unknown artifacts and drifts to a minimum. We use energy criteria of wavelet packet transform (WPT) for optimization based tuning of the IIR filter parameters. Such an optimum filter enforces that the energy distribution of the pre-stimulus parts in different experiments are almost overlapped but under different stimuli the distributions of the energy get changed. The reported research may popularize plant signal processing, as a separate field, besides other conventional bioelectrical signal processing paradigms.This work was supported by EU FP7 project PLants Employed As SEnsor Devices (PLEASED), EC grant agreement number 296582

BRINE SHRIMP CYTOTOXIC ACTIVITY OF 50% AQUEOUS ETHANOLIC LEAF EXTRACT OF CALOTROPIS PROCERA R. BR

Objective: The objective of this work entails a preliminary screening of 50% aqueous ethanolic leaf extract of Calotropis procera for locating antitumoractivity.Methods: 50% aqueous ethanolic extract, obtained from dried powdered plant material of C. procera was partitioned sequentially in petroleumether, benzene, and chloroform. Each fraction thus obtained was concentrated in a vacuum evaporator. The residual mass was collected separatelyand dissolved in propylene glycol. The three samples were subjected to brine shrimp cytotoxic assay to locate if there may be any positive responseof antitumor activity.Result: It was found that the sample obtained from chloroform extract responded positively in brine shrimp test and showed lethal concentration(LC50 at which 50% individual dies) at the concentration of 5 mg/ml. Benzene extract showed LC at the concentration of 15 mg/ml and petroleumether showed LC50 at the concentration of 20 mg/ml.Conclusion: Proves the presence of antitumor phytochemicals in C. procera.Keywords: Antitumor compounds, Brine shrimp, Calotropis procera, Cytotoxic activity

Microbiological examination of milk in Tarakeswar, India with special reference to coliforms

A study was carried out to assess the milk quality in Tarakeswar, India with special reference to coliforms. By standard plate count (SPC) method, out of ten raw milk samples, the microbial colonies were found to be high in six samples and the colony content was low in rest four samples. Inpasteurized milk samples, the colonies were low in seven samples and high in three samples. The methylene blue test performed for raw milk samples showed that out of ten samples, the five samples were poor, two samples were fair, two samples were good and only one sample was found to be anexcellent. Out of ten pasteurized samples, nine samples were of good quality and one was found to be excellent. Bacterial colony was found to be opaque and metallic sheen in colour prepared from five raw milk samples, and by biochemical characterization it was identified as Escherichia col

Biotechnological potential of natural food grade biocolorants

Color becomes the most sensitive part of any commodity not only for its appeal but also it enhances consumer acceptability. In addition, the color of a food substance is important to indicate its freshness and safety that are also indices of good aesthetic and sensorial values. For natural color and additives, adherence to the norms of biosafety protocol, are limited. The demand for natural source of such compounds is increasing day by day because of awareness of positive health benefit out of natural compounds. It therefore, necessitates looking into natural sources of food grade colorants and their use potentials. It is found more justified to use the term biocolorant instead of biopigment. Since pigments are mostly water insoluble with exceptions of certain pigments of biological origin. This article includes the advancements of process development and other biotechnological aspects of natural food grade colorants

The incidence of liver injury in Uyghur patients treated for TB in Xinjiang Uyghur autonomous region, China, and its association with hepatic enzyme polymorphisms nat2, cyp2e1, gstm1 and gstt1.

BACKGROUND AND OBJECTIVE: Of three first-line anti-tuberculosis (anti-TB) drugs, isoniazid is most commonly associated with hepatotoxicity. Differences in INH-induced toxicity have been attributed to genetic variability at several loci, NAT2, CYP2E1, GSTM1and GSTT1, that code for drug-metabolizing enzymes. This study evaluated whether the polymorphisms in these enzymes were associated with an increased risk of anti-TB drug-induced hepatitis in patients and could potentially be used to identify patients at risk of liver injury. METHODS AND DESIGN: In a cross-sectional study, 2244 tuberculosis patients were assessed two months after the start of treatment. Anti-TB drug-induced liver injury (ATLI) was defined as an ALT, AST or bilirubin value more than twice the upper limit of normal. NAT2, CYP2E1, GSTM1 and GSTT1 genotypes were determined using the PCR/ligase detection reaction assays. RESULTS: 2244 patients were evaluated, there were 89 cases of ATLI, a prevalence of 4% 9 patients (0.4%) had ALT levels more than 5 times the upper limit of normal. The prevalence of ATLI was greater among men than women, and there was a weak association with NAT2*5 genotypes, with ATLI more common among patients with the NAT2*5*CT genotype. The sensitivity of the CT genotype for identifying patients with ATLI was 42% and the positive predictive value 5.9%. CT ATLI was more common among slow acetylators (prevalence ratio 2.0 (95% CI 0.95,4.20) )compared to rapid acetylators. There was no evidence that ATLI was associated with CYP2E1 RsaIc1/c1genotype, CYP2E1 RsaIc1/c2 or c2/c2 genotypes, or GSTM1/GSTT1 null genotypes. CONCLUSIONS: In Xinjiang Uyghur TB patients, liver injury was associated with the genetic variant NAT2*5, however the genetic markers studied are unlikely to be useful for screening patients due to the low sensitivity and low positive predictive values for identifying persons at risk of liver injury

Surfactants, its applications and effects on environment

Surfactant is being considered as a very demandable molecule in the field of chemistry. This paper reviews most important factors especially the uses of surfactants and their effects on environment. Evaluation of surfactants are based on examining the ability of the surfactant to maintain lower interfacial tension between target contaminant and water, satisfying lower CMCs, and sustaining lower sorption and precipitation to target substrate. Surfactant mixtures of anionic and nonionic surfactant are shown to be excellent candidates for robust surfactant cleaners. Keywords: Surfactant; Interfacial tension; Critical micelle Concentration; Anionic surfactant; Nonionic surfactant DOI: 10.3126/bibechana.v7i0.4047 BIBECHANA 7 (2011) 61-6