Analog Circuit Fault Detection Using Location of Poles

A method for detection of parametric faults occurring in linear analog circuits based on location of poles of the Circuit Under Test (CUT) is proposed. In the proposed method, the value of each component of the CUT is varied within its tolerance limit using monte carlo simulation. The upper and lower bounds of magnitude, phase angle, real part and imaginary part of all poles of the CUT are obtained. While testing, the locations of poles are obtained. If any one or more of the poles lies outside the tolerance limit then the CUT is declared faulty. The effectiveness of the proposed method is validated through two benchmark circuits like second order sallenkey band pass filter and fourth order leapfrog low pass filter.     

Electric control of magnon frequencies and magnetic moment of bismuth ferrite thin films at room temperature

Here, we report the tuning of room-temperature magnon frequencies from 473 GHz to 402 GHz (14%) and magnetic moment from 4 to 18 emu∕cm(3) at 100 Oe under the application of external electric fields (E) across interdigital electrodes in BiFeO(3) (BFO) thin films. A decrease in magnon frequencies and increase in phonon frequencies were observed with Magnon and phonon Raman intensities are asymmetric with polarity, decreasing with positive E (+E) and increasing with negative E (-E) where polarity is with respect to in-plane polarization P. The magnetoelectric coupling (α) is proved to be linear and a rather isotropic α?=?8.5?×?10(-12) sm(-1).     

Fish bone structure based data aggregation and routing in wireless sensor network: multi-agent based approach

Wireless sensor networks (WSNs) are constrained by limited node (device) energy, low network bandwidth, high communication overhead and latency. Data aggregation alleviates the constraints of WSN. In this paper, we propose a multi-agent based homogeneous temporal data aggregation and routing scheme based on fish bone structure of WSN nodes by employing a set of static and mobile agents. The primary components of fishbone structure are backbone and ribs connected to both sides of a backbone. A backbone connects a sink node and one of the sensor nodes on the boundary of WSN through intermediate sensor nodes. Our aggregation scheme operates in the following steps. (1) Backbone creation and identifying master centers (or nodes) on it by using a mobile agent based on parameters such as Euclidean distance, residual energy, backbone angle and connectivity. (2) Selection of local centers (or nodes) along the rib of a backbone connecting a master center by using a mobile agent. (3) Local aggregation process at local centers by considering nodes along and besides the rib, and delivering to a connected master center. (4) Master aggregation process along the backbone from boundary sensor node to the sink node by using a mobile agent generated by a boundary sensor node. The mobile agent aggregates data at visited master centers and delivers to the sink node. (5) Maintenance of fish bone structure of WSN nodes. The performance of the scheme is simulated in various WSN scenarios to evaluate the effectiveness of the approach by analyzing the performance parameters such as master center selection time, local center selection time, aggregation time, aggregation ratio, number of local and master centers involved in the aggregation process, number of isolated nodes, network lifetime and aggregation energy. We observed that our scheme outperforms zonal based aggregation scheme.     

TMAO Suppresses Megalin Expression and Albumin Uptake in Human Proximal Tubular Cells Via PI3K and ERK Signaling

Trimethylamine-N-oxide (TMAO) is a uremic toxin, which has been associated with chronic kidney disease (CKD). Renal tubular epithelial cells play a central role in the pathophysiology of CKD. Megalin is an albumin-binding surface receptor on tubular epithelial cells, which is indispensable for urine protein reabsorption. To date, no studies have investigated the effect of TMAO on megalin expression and the functional properties of human tubular epithelial cells. The aim of this study was first to identify the functional effect of TMAO on human renal proximal tubular cells and second, to unravel the effects of TMAO on megalin-cubilin receptor expression. We found through global gene expression analysis that TMAO was associated with kidney disease. The microarray analysis also showed that megalin expression was suppressed by TMAO, which was also validated at the gene and protein level. High glucose and TMAO was shown to downregulate megalin expression and albumin uptake similarly. We also found that TMAO suppressed megalin expression via PI3K and ERK signaling. Furthermore, we showed that candesartan, dapagliflozin and enalaprilat counteracted the suppressive effect of TMAO on megalin expression. Our results may further help us unravel the role of TMAO in CKD development and to identify new therapeutic targets to counteract TMAOs effects.     

Secure Remote User Mutual Authentication Scheme with Key Agreement for Cloud Environment

Authentication schemes are widely used mechanisms to thwart unauthorized access of resources over insecure networks. Several smart card based password authentication schemes have been proposed in the literature. In this paper, we demonstrate the security limitations of a recently proposed password based authentication scheme, and show that their scheme is still vulnerable to forgery and offline password guessing attacks and it is also unable to provide user anonymity, forward secrecy and mutual authentication. With the intention of fixing the weaknesses of that scheme, we present a secure authentication scheme. We show that the proposed scheme is invulnerable to various attacks together with attacks observed in the analyzed scheme through both rigorous formal and informal security analysis. Furthermore, the security analysis using the widely-accepted Real-Or-Random (ROR) model ensures that the proposed scheme provides the session key (SK) security. Finally, we carry out the performance evaluation of the proposed scheme and other related schemes, and the result favors that the proposed scheme provides better trade-off among security and performance as compared to other existing related schemes.

     

Impedance studies of polycrystalline tin oxide

Polycrystalline SnO₂ samples prepared in the laboratory were irradiated with 2 MeV He ions having doses of 3.62 × 10¹⁵ ion/cm². The ac small-signal electrical data acquired for the polycrystalline SnO₂ in the frequency (f) range 100 Hz ≤ f ≤ 1 MHz and temperature (T) range 26°C ≤ T ≤ 100°C revealed one semicircular relaxation in the impedance plane for the He implanted sample. However, two semicircular relaxations were obtained in the same plane for the samples without He implantation. The He implantation indicated enhancement in the donor density in the polycrystalline SnO₂ as depicted via terminal conductance (or resistance). An erratum to this article can be found at     

Imperfections and impurity phases in flux grown RCrO3 (R = La,Yb) single crystals

Results of scanning electron microscopy (SEM) and energy dispersive X-ray analytical (EDAX) investigations, conducted on some elevated structures displayed by flux grown rare earth orthochromite, RCrO₃ (R = La, Yb) crystals, are presented. The peculiar structures exhibited by crystal surfaces indicate imperfections and impurity phases. EDAX of elevated structures reveals the various phases to be composed of lead associated materials which may probably be either Pb₂CrO₅ or Pb₂OF₂ (flux). Other secondary crystallization of impurity phases, ROF (R = La, Yb) is illustrated in the case of RCrO₃ (R = La, Yb) crystals. The elevated structures illustrate their non-stoichiometric behaviour. Precipitation of impurity phases and formation of imperfections during the growth of RCrO₃ (R = La, Yb) crystals and their effect on the crystalline quality is discussed.     

Radiation dose from dissolved radon in potable waters of the Bangalore environment,South India

Potable waters from various locations of the Bangalore environment were investigated for their ²²²Rn concentrations by the emanometry method. About 94 groundwater (borewell) samples were analysed for ²²²Rn concentrations and found to vary in the range 5.3–283.4 Bq L^?1 with a mean value of 87 Bq L^?1. Frequency distribution showed the ²²²Rn concentration in a large number of samples in the range of 0–50 Bq L^?1. From the measured concentrations, the effective doses (lung and stomach) for the population of the region were estimated. The effective dose was found to vary from 42.6 to 2280.2 µSv y^?1 with a mean value 702.5 µSv y^?1. The effect of boiling of water showed a drastic reduction in the ²²²Rn concentration. The results of the present investigation are systematically analysed, compared with the literature values and discussed.     

Production of Starch Saccharifying Enzyme (Glucoamylase) in Solid Cultures

A laboratory process was established for the production of glucoamylase (amyloglucosidase) enzyme by Aspergillus niger (RRL isolate), using wheat bran of mixed particle size as main carbon source in solid cultures. The experimental studies were carried out in 500 ml conical flasks and subsequently in tray fermenters in static conditions. Experiments were conducted to monitor the impact of initial moisture content of the substrate as well as the steam cooking of the substrate on different atmospheric pressure on the productivity of the enzyme. An initial moisture level of 50–55% was found optimum for glucoamylase production when fermentation was carried out for 96h. Cooking of substrate at 1056 kg/cm² under steam for 30 min gave most desirable qualities in substrate.