Provable security of a pairing-free one-pass authenticated key establishment protocol for wireless sensor networks

Designing efficient as well as secure cryptographic protocols for resource-constrained applications is a challenging task. In this paper, we formally analyze the security of an efficient one-pass authenticated key establishment protocol, the 1P-AKE protocol, which is primarily proposed for resource-constrained sensor nodes devices in wireless sensor networks (WSNs). In contrast to the existing identity-based one-pass key establishment protocols, the 1P-AKE protocol does not require any bilinear pairing computation in order to establish a key. This feature makes it really attractive for resource-constrained application environments, such as WSNs, where pairing computations are too expensive. We show that in the random oracle model, the 1P-AKE protocol is a secure authenticated one-pass key establishment protocol under the computational Diffie–Hellman assumption. The performance of the 1P-AKE protocol is also discussed and compared with the existing relevant protocols.     

Comparison of electrothermal and hydride generation atomic absorption spectrometry for the determination of total arsenic in broiler chicken

The purpose of this study was to estimate total arsenic concentration in different tissues (leg, breast, liver and heart) of broiler chicken by hydride generation atomic absorption spectrometry (HGAAS) and graphite furnace atomic absorption spectrometry (GFAAS), prior to microwave assisted acid digestion. The accuracy of the techniques was evaluated by using certified reference material DORM-2. The percentage recoveries of total As were observed as 100.6% and 99.4% for HGAAS and GFAAS, respectively. The precision of the techniques, expressed as relative standard deviation, was observed as 1.71% and 4.18% for HGAAS and GFAAS measurements, respectively. The limits of detection for HGAAS and GFAAS were 0.025 μg/g and 0.052 μg/g, respectively. The concentrations of total arsenic in different tissues of broiler chicken were found in the range of 2.19–5.28, 2.15–5.22, 2.97–7.17 and 2.68–6.36 μg/g for leg, breast, liver and heart tissues, respectively. At a mean level of chicken consumption (60 g/person/day), people may ingest in the range of 72.0–85.1 μg arsenic/person/day from chicken alone.     

Basin Scale Water Resources Systems Modeling Under Cascading Uncertainties

Global change in climate and consequent large impacts on regional hydrologic systems have, in recent years, motivated significant research efforts in water resources modeling under climate change. In an integrated future hydrologic scenario, it is likely that water availability and demands will change significantly due to modifications in hydro-climatic variables such as rainfall, reservoir inflows, temperature, net radiation, wind speed and humidity. An integrated regional water resources management model should capture the likely impacts of climate change on water demands and water availability along with uncertainties associated with climate change impacts and with management goals and objectives under non-stationary conditions. Uncertainties in an integrated regional water resources management model, accumulating from various stages of decision making include climate model and scenario uncertainty in the hydro-climatic impact assessment, uncertainty due to conflicting interests of the water users and uncertainty due to inherent variability of the reservoir inflows. This paper presents an integrated regional water resources management modeling approach considering uncertainties at various stages of decision making by an integration of a hydro-climatic variable projection model, a water demand quantification model, a water quantity management model and a water quality control model. Modeling tools of canonical correlation analysis, stochastic dynamic programming and fuzzy optimization are used in an integrated framework, in the approach presented here. The proposed modeling approach is demonstrated with the case study of the Bhadra Reservoir system in Karnataka, India.     

Structural evolution of a Ta-filament during hot-wire chemical vapour deposition of Silicon investigated by electron backscatter diffraction

We report on the application of electron backscatter diffraction to investigate the structural changes of a tantalum filament operated at typical hot-wire chemical vapour deposition conditions for the synthesis of hydrogenated nanocrystalline silicon. Various tantalum-silicides, identified by electron backscatter diffraction, form preferentially along the length of the filament. The filament has a recrystallized Ta inner core and a TaSi₂ layer encapsulated with a Si layer at the cooler ends. The αTa₅Si₃, metastable Ta₅Si₃ and Ta₂Si phases formed in addition to recrystallized Ta and TaSi₂ at the centre regions. Cracks and porosity were prevalent throughout the length of the filament. The microstructural evolution of the aged tantalum filament can be ascribed to the thermal gradient along the filament length, recrystallization of Ta and the variation of silicon content within the filament.     

Investigation of charge transport mechanism in semiconducting La<Subscript>0.5</Subscript>Ca<Subscript>0.5</Subscript>Mn<Subscript>0.5</Subscript>Fe<Subscript>0.5</Subscript>O<Subscript>3</Subscript> manganite prepared by sol–gel method

Here in, we report the charge transport mechanism in semiconducting La_0.5Ca_0.5Mn_0.5Fe_0.5O₃ (LCMFO) polycrystalline material synthesized via sol–gel auto combustion route. X-ray diffraction (XRD) analysis confirmed the orthorhombic phase of the prepared material. Temperature dependent resistivity and impedance spectroscopy measurements have been carried out to probe the dielectric and electrical conduction mechanism which revealed a change of Mott variable range to the small polaronic hopping conduction mechanism around 303 K. The complex impedance and modulus spectra undoubtedly showed the contribution of both grain and grain boundary effect on the conduction properties of LCMFO. An equivalent circuit [(R_gbQ_gb) (R_gQ_g)] model has been used to address the electrical parameters associated with the different phases (grains and grain boundaries) having different relaxation times. The values of resistances of two phases obtained after fitting the equivalent circuit in the nyquist plot have been analyzed which confirmed the change of conduction mechanism around 303 K. The resultant change in conduction mechanism is also supported by the conductivity plots.     

Hazardous impact of toxic metals on tobacco leaves grown in contaminated soil by ultrasonic assisted pseudo-digestion: multivariate study

Tobacco leaves (Nicotiana tabacum L.), agricultural soil and pollute irrigated lake water samples were collected during 2005–2006 and analyzed for Cd and Ni by electrothermal atomic absorption spectrometry (ETAAS). A simple and efficient procedure was investigated for the complete decomposition of tobacco leaves using ultrasonic assisted acid pseudo-digestion method (UPDM). A Plackett–Burman experimental design was used as a multivariate strategy for the evaluation of seven factors/variables at once, while central composite were used to found optimum values of significant variables. The accuracy of the proposed methods was assessed by analyzing certified reference (CRM); Virginia tobacco leaves (CTA-VTL-2). The results being compared with those obtained by conventional wet acid digestion method. The result obtained by optimized method showed good agreement with the certified values and sufficiently high recovery 97.8 and 98.7% for Cd and Ni, respectively. Under optimal conditions, the detection limits (3σ) were evaluated to be 0.019 μg g⁻¹ for Cd and 0.37 μg g⁻¹ for Ni. The proposed method was successfully applied to the determination of Cd and Ni in raw, processed tobacco and different branded cigarettes samples.     

Temperature-dependence on the optical properties and the phase separation of polymer–fullerene thin films

A detailed study on the thermal transition of poly(3-hexylthiophene) (P3HT) and blends was investigated by differential scanning calorimetry, while the morphological, phase separation and the transformation in the optical properties were probed by thermal-atomic force microscopy (AFM), polarized optical microscopy (POM) and spectroscopic ellipsometry (SE). The inclusion of fullerenes on the polymer structure confirms the formation and evolution of a new endothermic transition at high temperatures. SE revealed that the refractive index and extinction coefficient of the films increased with annealing temperature up to 140 °C due to the suppressed diffusion of PCBM molecules into the blend. Annealing above 140 °C resulted in a decrease in the optical constants due to the formation of large “needle-like” crystals. This is due to the depletion of PCBM clusters near the “needle-like” structures; resulting from the diffusion of the PCBM molecules into the growing PCBM crystals or “needle-like” crystals as is evidenced by in situ thermal-AFM and POM. These findings indicate that annealing temperature of 140 °C is suitable for a P3HT:PCBM film to obtain the desired phase separation for solar cell application.     

Air pollution assessment in urban areas and its impact on human health in the city of Quetta, Pakistan

Nowadays, air over major cities throughout the world has become overburdened with gases produced by automobiles. The death rate due to automobile pollution is increasing rapidly in the metropolitan areas. With passage of time, people realized that polluted air has serious effects on their health, climate and economics. Weather and climate have integrated impact on human activities resulting in worldwide concentration of the particulates of environmental pollution, viz., chlorofluorocarbons, carbon dioxide, methane, nitrogen oxide, lead and several other dust and gaseous particles. Like many other mega cities in the world the ambient air quality of Quetta, Pakistan is also deteriorating nowadays. Automobile exhausts and certain industrial pollutants produce O₃ by photochemical reactions. The particulate matter, particularly less than 10 μm in size, can pass through the natural protective mechanism of human respiratory system and plays an important role in genesis and augmentation of allergic disorders. Sources of air pollution in the area and the unique problem arising out of the emission from the vehicles, industries, etc. have been described. Ambient air quality was monitored along with micrometeorological data and the results are discussed. The status of air pollution in the area has been evaluated and a questionnaire survey was conducted to estimate the allergic symptoms and exposure to assess the respiratory disorders. The data are analyzed to evaluate the critical situation arising out of the emission of air pollutants and the impact on human health due to respirable diseases (RDs) in middle class sub-population (activity-wise) in the area assessed. A strategic air quality management plan has been proposed. For the mitigation of air pollution problems in the city, different measures to be adopted to maintain the balance between sustainable development and environmental management have been discussed. Air pollution has significant effects on exacerbation of asthma, allergy and other respiratory diseases.