Topology Control for Delay Sensitive Applications in Wireless Sensor Networks

Wakeup scheduling in wireless sensor networks is known as the most effective way to conserve the limited amount of available energy for each sensor node. Such schedules are applicable to protocols of different network layers and often result in higher latency. Tolerance to latency varies greatly depending on the application so that it is low for a large class of delay sensitive applications. In this paper, we present a unified approach in the design of wakeup schedules in different network layers. A new distributed wakeup schedule is introduced in the context of topology control which aims to conserve more energy while not compromising on the delay performance of the system. The proposed protocol addresses the problem of increasing the network longevity for a given upper bound on the average end-to-end delay. In this scheme neither localization nor synchronization is required and only local information about the network topology is used. In addition to its simplicity of implementation, its energy overhead is negligible and it implicitly determines the routing paths. Our simulation results show that the performance of this protocol is close to the optimal schedule and significantly higher than SPAN, an existing topology control mechanism.     

Advanced simulation tool for FeRAM design

Abstract

A ferroelectric capacitor model was derived, and a ferroelectric device library was implemented into SPICE (both PSPICE and HSPICE) simulation tool. With this SPICE model, 1T-1C/2T-2C, or any other ferroelectric circuit, such as FeFET, chain cell, link cell can be simulated accurately and in real-time. Simulations of hysteresis loops, TVS, switching characteristics are shown in this paper.     

Application layer QoS optimization for multimedia transmission over cognitive radio networks

In cognitive radio (CR) networks, the perceived reduction of application layer quality of service (QoS), such as multimedia distortion, by secondary users may impede the success of CR technologies. Most previous work in CR networks ignores application layer QoS. In this paper we take an integrated design approach to jointly optimize multimedia intra refreshing rate, an application layer parameter, together with access strategy, and spectrum sensing for multimedia transmission in a CR system with time varying wireless channels. Primary network usage and channel gain are modeled as a finite state Markov process. With channel sensing and channel state information errors, the system state cannot be directly observed. We formulate the QoS optimization problem as a partially observable Markov decision process (POMDP). A low complexity dynamic programming framework is presented to obtain the optimal policy. Simulation results show the effectiveness of the proposed scheme.     

Getting ready to translate: cytoplasmic maturation of eukaryotic ribosomes

The ribosome is the 'universal ribozyme' that is responsible for the final step of decoding genetic information into proteins. While the function of the ribosome is being elucidated at the atomic level, in comparison, little is known regarding its assembly in vivo and intracellular transport. In contrast to prokaryotic ribosomes, the construction of eukaryotic ribosomes, which begins in the nucleolus, requires >200 evolutionary conserved non-ribosomal trans-acting factors, which transiently associate with pre-ribosomal subunits at distinct assembly stages and perform specific maturation steps. Notably, pre-ribosomal subunits are transported to the cytoplasm in a functionally inactive state where they undergo maturation prior to entering translation. In this review, I will summarize our current knowledge of the eukaryotic ribosome assembly pathway with emphasis on cytoplasmic maturation events that render pre-ribosomal subunits translation competent.     

Effect of Zirconium on the Densification of Reactively Hot‐Pressed Zirconium Carbide

Densification mechanisms involved during reactive hot pressing (RHP) of zirconium carbide (ZrC) have been studied. RHP has been carried out using zirconium (Zr) and graphite (C) powders in the molar ratios 1:0.5, 1:0.67, 1:0.8, and 1:1 at 40 MPa, 800°C–1200°C for different durations. The volume fractions of phases formed, including porosity, are determined from the measured density and from Rietveld analysis. Increased densification with an increasing nonstoichiometry in carbon has been observed. Microstructural and X‐ray diffraction observations coupled with the predictions of a model based on the constitutive laws governing plastic flow of zirconium suggest that the better densification of nonstoichiometric compositions arise from the higher amount of starting Zr and also the longer duration of its availability for plastic flow during RHP. Volume shrinkage due to reaction between Zr and C and the gradual elimination of the soft metal phase limit the final density achievable. Based on these observations, a two‐step RHP carried out at 800°C and 1200°C leads to a better densification than a single RHP at 1200°C.     

Combinatory Effects of Cerium Dioxide Nanoparticles and Acetaminophen on the Liver—A Case Study of Low-Dose Interactions in Human HuH-7 Cells

The interactions between pharmaceuticals and nanomaterials and its potentially resulting toxicological effects in living systems are only insufficiently investigated. In this study, two model compounds, acetaminophen, a pharmaceutical, and cerium dioxide, a manufactured nanomaterial, were investigated in combination and individually. Upon inhalation, cerium dioxide nanomaterials were shown to systemically translocate into other organs, such as the liver. Therefore we picked the human liver cell line HuH-7 cells as an in vitro system to investigate liver toxicity. Possible synergistic or antagonistic metabolic changes after co-exposure scenarios were investigated. Toxicological data of the water soluble tetrazolium (WST-1) assay for cell proliferation and genotoxicity assessment using the Comet assay were combined with an untargeted as well as a targeted lipidomics approach. We found an attenuated cytotoxicity and an altered metabolic profile in co-exposure experiments with cerium dioxide, indicating an interaction of both compounds at these endpoints. Single exposure against cerium dioxide showed a genotoxic effect in the Comet assay. Conversely, acetaminophen exhibited no genotoxic effect. Comet assay data do not indicate an enhancement of genotoxicity after co-exposure. The results obtained in this study highlight the advantage of investigating co-exposure scenarios, especially for bioactive substances.     

Post mortem changes of the elemental composition of autopsy specimens: Variations of K,Na, Mg,Ca, Cl,Fe, Zn,Cu, Mn and Rb in rat liver

Retaining the liver inside the intact dead body for different periods of time at ambient temperature induced significant differences in its weight due to post mortem tissue degeneration. Livers from animals that were frozen at ?15°C also showed significant decrease in weight upon thawing on the third day. The effect of these changes on the concentrations of various elements was reflected differently depending upon the association of the elements with extracellular fluids and intracellular components. Thus, concentration of K was more affected by the lysis of the cell and sustained losses up to 30 per cent in relation to the control values, while the total content was reduced by more than 40 per cent as a result of both lysis and partial liquefaction. For Na, differences ranging from +10 to ?20 per cent in concentrations, and +20 to ?40 per cent in total content were observed which could be explained by fluid movements in and out of the organ. Mg and Cl essentially resembled K and Na, respectively. Ca concentration from the animals exposed to ambient temperature was unpredictable due to its mobilization from the decaying residual food in the GI-Tract. Among the trace elements, variations observed for Fe ranged from ?20 and +40 per cent, while both Cu and Zn were found to fluctuate between ?20 and +20 per cent. The loss observed in the total content in liver for the 5 trace elements studied (Cu, Fe, Mn, Rb and Zn) was found to be about 20 to 40 per cent. Rinsing of the liver samples with distilled water depleted the electrolyte concentration up to 30 per cent. Among the trace elements, while Cu, Fe and Zn were relatively unaffected, the losses were up to 20 per cent both for Mn and Rb. It is concluded that livers autopsied on different days are apt to introduce serious systematic errors and that, it is very important to standardize the sampling time for autopsy cases.     

Mechanism of disinfection: Effect of chlorine on cell membrane functions

To elucidate the mechanism of disinfection by chlorine, its effects on some vital properties associated with cell membrane of Escherchia coli were studied. There was no significant change in Zeta potential at bactericidal doses of chlorine. Treatment with chlorine induced the leakage of macromolecules from the cells indicating the permeability changes of the membrane. Proteins and RNA were detected in the supernatant when the cells were treated with chlorine dose of 1.5 mg 1⁻¹ (100 μg Cl mg⁻¹ N). The presence of DNA was observed only at high chlorine doses. The studies on oxidative phosphorylation of cell free extract indicated the complete cessation of phosphate uptake at a dose of 0.4 mg 1⁻¹ (30 μg Cl mg⁻¹ N). There was about 70% decrease in the oxygen uptake corresponding to chlorine dose of 0.8 mg 1⁻¹.     

Evaluation of two commercial field test kits used for screening of groundwater for arsenic in Northern India

In this study two relatively new arsenic field kits, namely Wagtech Digital Arsenator (WFTK) and Chem-In Corp field test kit (CFTK) for arsenic were evaluated. The response of the two field test kits to known standards (Both As(III) and As(V)) is detailed. In addition around 157 arsenic-contaminated field samples obtained from various locations of Ballia and Kanpur districts, U.P., India were tested using the two kits and the results were compared with the laboratory-based colorimetric method (silver diethyldithiocarbamate method, SDDC). The concentration of arsenic in the 157 samples ranged from 0 to 468 microg l(-1). WFTK is seen to be suitable for measuring arsenic concentration <5-100 microg l(-1) using the digital meter. CFTK was not able to detect As(V) and its usage is cautioned in Uttar Pradesh where As(V) is seen to occur in appreciable concentrations. The Pearson's correlation between the silver diethyldithiocarbamate method and WFTK was found to be 0.87 and for the corresponding correlation with CFTK was 0.41 in the concentration range used in this study. Spearman's rank correlation coefficients comparing the WFTK and CFTK to laboratory measurements in the concentration range of 0-100 microg l(-1) were 0.95 (p<0.001) and 0.64 (p<0.001) respectively.     

Guava (Psidium guajava) leaf powder: novel adsorbent for removal of methylene blue from aqueous solutions

Batch sorption experiments were carried out using a novel adsorbent, guava leaf powder (GLP), for the removal of methylene blue (MB) from aqueous solutions. Potential of GLP for adsorption of MB from aqueous solution was found to be excellent. Effects of process parameters pH, adsorbent dosage, concentration, particle size and temperature were studied. Temperature-concentration interaction effect on dye uptake was studied and a quadratic model was proposed to predict dye uptake in terms of concentration, time and temperature. The model conforms closely to the experimental data. The model was used to find optimum temperature and concentration that result in maximum dye uptake. Langmuir model represent the experimental data well. Maximum dye uptake was found to be 295mg/g, indicating that GLP can be used as an excellent low-cost adsorbent. Pseudo-first-order, pseudo-second order and intraparticle diffusion models were tested. From experimental data it was found that adsorption of MB onto GLP follow pseudo second order kinetics. External diffusion and intraparticle diffusion play roles in adsorption process. Free energy of adsorption (DeltaG degrees ), enthalpy change (DeltaH degrees ) and entropy change (DeltaS degrees ) were calculated to predict the nature of adsorption. Adsorption in packed bed was also evaluated.