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The terrestrial biosphere plays a pivotal role in removing carbon from the atmosphere. The removal processes are primarily affected by the presence of extreme temperature in the atmosphere. Little information is available on carbon removal response by the terrestrial biosphere during extreme temperature events over the Indian region. India has witnessed frequent and intense heatwaves in the recent past, and future projections about the frequency of heatwave occurrence suggest a further increase in the changing climate scenario. This study used surface CO2 flux observations and satellite retrieved columnar and mid-tropospheric CO2 concentrations to understand atmospheric CO2 variability and its transport patterns with anomalously high-temperature events such as heatwave conditions over India. Intensification of temperature up to 32 °C has increased the atmosphere-biosphere CO2 fluxes (carbon sink). But further intensification in temperature (> 32–33 °C), like those observed during heatwaves, tends to drive the ecosystem to act as a CO2 source into the atmosphere due to reduced ability to absorb atmospheric CO2. Such excess CO2 fluxes may lead to change in the atmospheric CO2 concentration via atmospheric circulation or the vertical transport of the air masses from the near-surface to the upper levels in the atmosphere. The satellite observed CO2 concentration is elevated by 2–3 ppm during the heatwave conditions over India. The impact of extreme temperature on the biospheric sink capability in the carbon cycle, leading to an increase in the atmospheric CO2 concentration, is one of the significant outcomes of this study.

Authors:Smrati Gupta1,2*, Yogesh K. Tiwari1, J. V. Revadekar1, Pramit Kumar Deb Burman1, Supriyo Chakraborty1, Palingamoorthy Gnanamoorthy3,41Indian Institute of Tropical Meteorology, Pune, Ministry of Earth Sciences, Govt. of India2Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India3Coastal Systems Research, M. S. Swaminathan Research Foundation, Chennai, India4Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Menglun, ChinaAbstract A significant amount of the major greenhouse gas, carbon dioxide (CO2), released into the atmosphere is sequestered by the terrestrial biosphere. Climatic parameters such as temperature, precipitation, soil moisture, etc., modulate this sequestration capacity or sink in varied limits. A little information is available on the impact of extreme temperatures on the terrestrial biosphere sequestration of atmospheric CO2. This study explores the modulation in the terrestrial sink of CO2 caused by the frequently occurring extreme temperature phenomenon such as heatwaves over the Indian domain. Heatwaves are extreme temperature phenomena extending from the North-west Indian region towards the south-east region, occurring primarily in the pre-monsoon season of March-May (MAM), sometimes prolonged until June. The high intensity and duration of heatwaves during the season lead to the loss of human work capacity, health, economic losses, and even lives. The year 2015 witnessed one of the dreadful heatwave events in recent years, resulting in the loss of more than 2500 human lives within a season owing to heatwaves. The frequency and intensity of heatwaves are projected to increase further soon globally, including India, in the light of global climate change. It is not only of concern for human resources.From the biosphere perspective, the terrestrial sink of CO2 has also been studied to get affected by heatwaves. Temperature is one of the prime factors responsible for photosynthesis and ultimately for the available atmospheric CO2 fixation by the plants. As such, the CO2 fixation by the biosphere is affected during MAM season due to limited reduced soil moisture in this hot and dry season, leading to higher atmospheric CO2 concentrations. In this study, we examine the sub-seasonal variability in the atmospheric CO2 observed within MAM, driven by subdued fixation by ecosystems in the presence of extreme temperature phenomena like heatwaves. Here, available observations of CO2 flux or Net Ecosystem Exchange (NEE) flux from MetFlux India Project funded by the Ministry of Earth Sciences, India, studied in conjunction with the retrieved atmospheric and columnar CO2 concentrations from instruments aboard Atmospheric Infrared Sounder and Orbiting Carbon Observatory-2 satellites during the heatwave period of the year 2015. Our results suggest during a heatwave period, there is an initial increase in carbon uptake by the ecosystem with the temperature rise. But a further rise in temperature after some critical high temperature (~ 32 ͦ C) tends to reduce CO2 uptake compared to the non-heatwave period of the same season. The satellite retrievals also noticed an increase in atmospheric CO2 concentrations by 2-3 ppm during the heatwave period. The impact and feedback of heatwaves on the biospheric component of the carbon cycle is one of the significant outcomes of this study.

This paper presents NANCY, a system that generates adaptive bit rates (ABR) for video and adaptive network coding rates (ANCR) using reinforcement learning (RL) for video distribution over wireless networks. NANCY trains a neural network model with rewards formulated as quality of experience (QoE) metrics. It performs joint optimization in order to select: (i) adaptive bit rates for future video chunks to counter variations in available bandwidth and (ii) adaptive network coding rates to encode the video chunk slices to counter packet losses in wireless networks. We present the design and implementation of NANCY, and evaluate its performance compared to state-of-the-art video rate adaptation algorithms including Pensieve and robustMPC. Our results show that NANCY provides 29.91% and 60.34% higher average QoE than Pensieve and robustMPC, respectively., Comment: Accepted in Globecom, 2020

Industry in all sectors is experiencing a profound digital transformation that puts software at the core of their businesses. In order to react to continuously changing user requirements and dynamic markets, companies need to build robust workflows that allow them to increase their agility in order to remain competitive. This increasingly rapid transformation, especially in domains like IoT or Cloud computing, poses significant challenges to guarantee high quality software, since dynamism and agile short-term planning reduce the ability to detect and manage risks. In this paper, we describe the main challenges related to managing risk in agile software development, building on the experience of more than 20 agile coaches operating continuously for 15 years with hundreds of teams in industries in all sectors. We also propose a framework to manage risks that considers those challenges and supports collaboration, agility, and continuous development. An implementation of that framework is then described in a tool that handles risks and mitigation actions associated with the development of multi-cloud applications. The methodology and the tool have been validated by a team of evaluators that were asked to consider its use in developing an urban smart mobility service and an airline flight scheduling system., 11 pages and 7 images (+1 for the logo). This paper is a postprint of a paper submitted to and accepted for publication in IET Software (Vol. 13 , Iss. 3 , 6 2019) and issubject to Institution of Engineering and Technology Copyright. The copy of record is available at the IET Digital Library

Blast, also known as leaf spot, caused by Pyricularia grisea (teleomorph: Magnaporthe grisea), has emerged as a serious disease affecting both forage and grain production in pearl millet in India. Pathogenic variation was studied in a greenhouse using 25 M. grisea isolates collected from four major pearl-millet-growing states in India (Rajasthan, Haryana, Maharashtra, and Uttar Pradesh) on 10 pearl millet genotypes (ICMB 02444, ICMB 02777, ICMB 06444, ICMB 93333, ICMB 96666, ICMB 97222, ICMB 99444, 863B, ICMR 06222, and ICMB 95444). Differential reactions to the test isolates were recorded on ICMB 02444, ICMB 93333, ICMB 97222, 863B, and ICMR 06222. The 25 isolates were grouped into five different pathotypes based on their reaction types (virulent = score ≥ 4 and avirulent = score ≤ 3 on a 1-to-9 scale). For the identification of resistance sources, a pearl millet mini-core comprising 238 accessions was evaluated under greenhouse conditions against five M. grisea isolates (Pg118, Pg119, Pg56, Pg53, and Pg45) representing the five pathotypes. Of 238 accessions, 32 were found to be resistant to at least one pathotype. Resistance to multiple pathotypes (two or more) was recorded in several accessions, while three accessions (IP 7846, IP 11036, and IP 21187) exhibited resistance to four of the five pathotypes. Four early-flowering (≤50 days) blast-resistant mini-core accessions (IP 7846, IP 4291, IP 15256, and IP 22449) and four accessions (IP 5964, IP 11010, IP 13636, and IP 20577) having high scores (≥7) for grain and green fodder yield potential and overall plant aspect were found to be promising for utilization in pearl millet improvement programs. Identification of five pathotypes of M. grisea and sources of resistance to these pathotypes will provide a foundation for breeding for blast resistance in pearl millet in India.

In-memory cluster computing platforms have gained momentum in the last years, due to their ability to analyse big amounts of data in parallel. These platforms are complex and difficult-to-manage environments. In addition, there is a lack of tools to better understand and optimize such platforms that consequently form the backbone of big data infrastructure and technologies. This directly leads to underutilization of available resources and application failures in such environment. One of the key aspects that can address this problem is optimization of the task parallelism of application in such environments. In this paper, we propose a machine learning based method that recommends optimal parameters for task parallelization in big data workloads. By monitoring and gathering metrics at system and application level, we are able to find statistical correlations that allow us to characterize and predict the effect of different parallelism settings on performance. These predictions are used to recommend an optimal configuration to users before launching their workloads in the cluster, avoiding possible failures, performance degradation and wastage of resources. We evaluate our method with a benchmark of 15 Spark applications on the Grid5000 testbed. We observe up to a 51% gain on performance when using the recommended parallelism settings. The model is also interpretable and can give insights to the user into how different metrics and parameters affect the performance.

Tremendous growth and adoption of cloud based services within IT enterprises has generated important requirements for security provisioning. Users need to evaluate the security characteristics of different providers and their offered services. This generates an additional requirement for methods to compare cloud service providers on the basis of their capabilities to meet security requirements. This paper proposes a novel framework to assess and compare cloud services on the basis of their security offerings, leveraging existing best practices and standards to develop new relevant metrics. We provide comparison yardsticks related to security to evaluate cloud services such that the security robustness of cloud services can be computed using easy to evaluate deconstructed metrics. This paper provides a framework that can be leveraged to provide security enhancement plans both for users and providers.

Novel catalytically active nanocomposite surfaces are fabricated by in situ synthesis of palladium or platinum nanoparticles inside poly(2-vinylpyridine) (P2VP) brushes, used as a nano-reactor. Focusing on the revelation of the interaction of the metal species with P2VP, the immobilization is investigated by X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform IR (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), as well as scanning electron microscopy (SEM) and transmission electron micro­scopy (TEM). Homogeneous distribution of nanoparticles is achieved. The mechanism of nanoparticle formation is investigated by study­ing the influence of particular reaction parameters and the catalytic activity of the nanocomposites is confirmed using a model reaction.

In the application economy, digital business initiatives are at the forefront of the growth strategy of many companies. Cloud based solutions offer a significant competitive advantage for both large companies and SMEs, leading to a rapid increase in the number of Cloud Service Providers (CSP). An important CSP driver is the improvement of consumers’ experience through digital platforms that allow users to access data and services from any location and through multiple channels with assured performance and availability.

International audience; The recent increase in the use of wireless networks for video transmission has led to the increase in the use of rate-adaptive protocols to maximize the resource utilization and increase the efficiency in the transmission. However, a number of these protocols lead to interactions among the users that are subjective in nature and affect the overall performance. In this paper, we present an in-depth analysis of interplay between the wireless network dynamics and video transmission dynamics in the light of subjective perceptions of the end users in their interactions. We investigate video exchange applications in which two users interact repeatedly over a wireless relay channel. Each user is driven by three conflicting objectives: maximizing the Quality of Service (QoS) and Quality of Experience (QoE) of the received video, while minimizing the transmission cost. Non-cooperative repeated games model precisely interactions among users with independent agendas. We show that adaptive video exchange is impossible if the duration of the interaction is determined. However, if the users interact indefinitely, they achieve cooperation via exchange of video streams. Our simulations evidence the tradeoff between users’ QoS and QoE of their received video. The expected duration of the interaction plays a role and draws the region of solution trade-offs. We propose further means of shaping this region using Pareto optimality and user-fairness arguments. This work proposes a concrete game theoretical framework that allows the optimal use of traditional protocols by taking into account thesubjective interactions that occur in practical scenarios.

In recent years, a variety of nano-(micro) scale organic–inorganic composite particles with well defined chemical composition, size and morphology have been fabricated and their applications in wide spectrum of cutting-edge technological areas have been explored. This review is focused on recent developments towards various fabrication methodologies and applications of such colloid based composite particles. Strategies for preparation of nano and micro scale composite materials are presented by choosing as examples hard core based composite particles having core–shell and raspberry-like morphologies and soft core based composite microgels. Applications of these materials in wide range of potential areas are discussed including the fabrication of colloidal crystal arrays, hollow spheres, superhydrophobic surfaces, filler carriers and smart nanomaterials.

We report on the fabrication of three-dimensional colloidal crystal arrays (CCAs) on an underlying substrate via gravity sedimentation of TiO(2)-coated polystyrene (PS) colloidal particles. The beauty of the described system lies in the fact that, obtained CCAs, for the first time, display a photonic band gap in the near-infrared (NIR) region with as much bandwidth (Delta lambda/lambda) as 54-61%. Interestingly, stop band position and bandwidth have been found to be modulated with structural parameters of building blocks such as particle size and thickness of TiO(2) shell, etc. Moreover, no significant change in stop band position was observed with the variation in incidence angle of the light. Theoretical calculations from the simulation studies have been found in agreement with the experimental findings. Journal of Physical Chemistry C

A simple, facile and versatile approach is presented for the preparation of PMMA/ZnO nanocomposite materials, which possess high transparency, no color, good thermal stability, UV absorption and improved mechanical properties. The employed process involved mixing of ZnO nanoparticles dispersed in DMAc with the PMMA matrix dissolved in the same solvent. The effect of ZnO content on the physical properties of the PMMA matrix is studied. A significant improvement in mechanical properties was observed with the incorporation of 0.5 wt.-% ZnO particles. The beauty of the described approach lies in the fact that despite being a simple and facile approach, it offers nano-level (2―5 nm) mixing of ZnO nanoparticles into a polymer matrix.

A simple, fast, and versatile approach to the fabrication of outstanding surface enhanced Raman spectroscopy (SERS) substrates by exploiting the optical properties of the Ag nanoparticles and functional as well as organizational characteristics of the polymer brushes is reported. First, poly(2-(dimethylamino)ethyl methacrylate) brushes are synthesized directly on glassy carbon by self-initiated photografting and photopolymerization and thoroughly characterized in terms of their thickness, wettability, morphology, and chemical structure by means of ellipsometry, contact angle, AFM, and XPS, respectively. Second, Ag nanoparticles are homogeneously immobilized into the brush layer, resulting in a sensor platform for the detection of organic molecules by SERS. The surface enhancement factor (SEF) as determined by the detection of Rhodamine 6G is calculated as 6T10 6 .

In this study, we report on the fabrication of the nanoassemblies consisting of the poly(N-isopropyl acrylamide) (PNIPAAm) brushes immobilized with gold nanoparticles (Au NPs). The employed process involves grafting of the carboxyl terminated PNIPAAm chains on an underlying substrate in a brush conformation followed by the immobilization of surface functionalized Au NPs by means of physical interaction (hydrogen bonding). Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and UV−vis spectroscopy have been employed to characterize the prepared PNIPAAm−Au nanoassemblies. Polymer brushes have been found to suppress the nanoparticles’ aggregation and, hence, facilitate the complete surface coverage. Furthermore, we demonstrated the application of resulting PNIPAAm−Au nanoassemblies in the fabrication of the temperature nanosensors. The employed approach is simple and highly versatile for the modification of macroscopic surfaces with a wide range of NPs.

A novel and versatile approach for the mixing of ZnO nanofillers into a host polymer matrix, poly(ethyl methacrylate) (PEMA), is reported. Firstly, ZnO nanoparticles are deposited onto the surface of polystyrene (PS) colloidal particles in a "raspberry-like" fashion and subsequently obtained PS/ZnO composite particles are mixed into the PEMA matrix in the range of 0.5 to 5 wt.-%. Microscopic analyses reveal a homogenous distribution of PS/ZnO domains into the PEMA matrix even at 5 wt.-% loading level. Thermogravimetric analysis and differential scanning calorimetry results indicate an improvement in thermal stability of PEMA matrix after mixing with PS/ZnO filler particles. A significant enhancement in mechanical properties of PEMA matrix in the presence of PS/ZnO particles has been evidenced by dynamic mechanical analysis and three point bending measurements.

A facile approach for the fabrication of hierarchically nanostructured hollow spheres composed of mixed metal oxides (ZnO−TiO2) has been demonstrated. The employed protocol involves coating of the functionalized polystyrene (PS) template beads with the successive layers of ZnO and TiO2 nanoparticles, respectively, followed by the calcination of resulting PS/ZnO−TiO2 core shell composite particles at elevated temperature. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been employed to evidence the fabrication of the monodisperse, intact, and closed ZnO−TiO2 hollow spheres. Presence of both ZnO and TiO2 phases in the ceramic shell of resulting hollow spheres has been confirmed by electron energy loss mapping analysis. Phase purity of the ZnO and TiO2 phases of the ceramic shell has been studied by X-ray diffraction analysis. Brunauer−Emmett−Teller (BET) method reveals the specific surface area and the average pore diameter of hollow spheres as 59.63 m2/g and 3 nm, respect...

We report on the immobilization of gold nanoparticles on end-functionalized and solvent responsive polystyrene brushes, grafted on an underlying substrate. The presence of gold nanoparticles on polystyrene brushes was confirmed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The resulting polystyrene−Au nanoassemblies have been used as the nanosensors for the detection of a variety of organic solvents in surrounding media. The sensing mechanism is based upon the change in the proximity of the immobilized gold nanoparticles as a consequence of the solvent induced reversible swelling−deswelling of polystyrene chains. The sensing ability was demonstrated by a simple analytic tool, i.e., UV−vis spectroscopy, through a shift in plasmon resonance band of immobilized Au nanoparticles. A dramatic blue shift of 32 nm in the surface resonance band was observed as the surrounding media of Au immobilized polystyrene brushes (Au−PS) was changed from air to the toluene. The described approa...

We report on a facile route for the immobilization of silver nanoparticles (Ag NPs) onto the pH-responsive poly(2-vinylpyridine) (P2VP) brushes. The process involves chemical grafting of P2VP chains on the underlying substrate in brush conformation followed by the in situ synthesis of Ag NPs via chemical reduction of silver nitrate (AgNO3) in the presence of P2VP brushes. The effect of various reaction parameters, such as the employed concentration of AgNO3 salt and reduction time on the immobilization process, has been demonstrated. The quantitative analysis of the loaded amount and surface coverage of the Ag NPs on polymer brushes as a function of the employed AgNO3 salt concentration has been discussed. Immobilization of Ag NPs onto the P2VP brushes has been confirmed by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–vis) spectroscopy. Finally, the system was used to fabricate the nanosensors for detecting the pH of surrounding aqueous medium. The con...

We report on a generic approach for immobilizing quantum dots (CdTe nanoparticles) on thin, fluid films consisting of poly(acrylic acid) (PAA) polymer chains tethered by one end to an underlying substrate in a polymer brush configuration. The protocol involves covalent bonding (amide linkage) between amino groups present on the surface of CdTe nanoparticles and carboxylic groups of PAA polymer chains. The thickness of the PAA polymer brush employed (∼4.5 nm) is comparable to the nanoparticle size. Exploitation of such a thin polymer brush was found to suppress nanoparticle aggregation and facilitates complete surface coverage. Atomic force microscopy (AFM) was used to study the film morphology. Covalent linkage between nanoparticles and polymer brushes was proven by X-ray photoelectron spectroscopy (XPS). The change in the optical properties of the quantum dots after immobilization was studied by photoluminescence spectroscopy and fluorescence microscopy. The results suggest a simple, effective and highly versatile method for modification of various surfaces with different nanoscopic particles.

The aim of this work was the development of a versatile route for the preparation of temperature- and pH-responsive hydrogels with small dimensions. The copolymerization of N,N-dimethylaminoethyl methacrylate with various amounts (5 and 10 mol %) of dimethylmaleimidoethyl methacrylate in solution with 2,2′-azobisisobutyronitrile as an initiator is described. The structural and molecular characterization of the copolymers was performed with proton nuclear magnetic resonance, Fourier transform infrared, and ultraviolet spectroscopy, as well as size exclusion chromatography. Differential scanning calorimetry and thermogravimetry were used for the thermal characterization of the copolymers. Micro- and nanohydrogels of the copolymers were prepared by photocrosslinking. The gels obtained by photocrosslinking were characterized with a combination of surface plasmon resonance and optical waveguide spectroscopy, dynamic light scattering, and scanning electron microscopy. The hydrogels showed temperature- and pH-responsive behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 669–679, 2007

The growth in the number of cloud computing users has led to the availability of a variety of cloud based services provided by different vendors. This has made the task of selecting a suitable set of services quite difficult. There has been a lot of research towards the development of suitable decision support system (DSS) to assist users in making an optimal selection of cloud services. However, existing decision support systems cannot address two crucial issues: firstly, the involvement of both business and technical perspectives in decision making simultaneously and, secondly, the multiple-clouds services based selection using a single DSS. In this paper, we tackle these issues in the light of solving the problem of cloud service discovery. In particular, we present the following novel contributions: Firstly, we present a critical analysis of the state-of-the-art in decision support systems. Based on our analysis, we identify critical shortcomings in the existent tools and develop the set of requirements which should be met by a potential DSS. Secondly, we present a new holistic framework for the development of DSS which allows a pragmatic description of user requirements. Additionally, the data gathering and analysis is studied as an integral part of the proposed DSS and therefore, we present concrete algorithms to assess the data for an optimal service discovery. Thirdly, we assess our framework for applicability to cloud service selection using an industrial case study. We also demonstrate the implementation and performance of our proposed framework using a prototype which serves as a proof of concept. Overall, this paper provides a novel and holistic framework for development of a multiple cloud service discovery based decision support system.

13 pages, 5 figures, supporting information http://dx.doi.org/10.1002/2014JD022687, One of the critical parameters in assessing the global impacts of dimethyl sulfide (DMS) on cloud properties and the radiation budget is the estimation of phytoplankton-induced ocean emissions, which are derived from prescribed, climatological surface seawater DMS concentrations. The most widely used global ocean DMS climatology was published 15 years ago and has recently been updated using a much larger database of observations. The updated climatology displays significant differences in terms of the global distribution and regional monthly averages of sea surface DMS. In this study, we use the ECHAM5-HAMMOZ aerosol-chemistry-climate general circulation model to quantify the influence of the updated DMS climatology in computed atmospheric properties, namely, the spatial and temporal distributions of atmospheric DMS concentration, sulfuric acid concentration, sulfate aerosols, number of activated aerosols, cloud droplet number concentration, and the aerosol radiative forcing at the top of the atmosphere. Significant differences are observed for all the modeled variables. Comparison with observations of atmospheric DMS and total sulfate also shows that in places with large DMS emissions, the updated climatology shows a better match with the observations. This highlights the importance of using the updated climatology for projecting future impacts of oceanic DMS emissions, especially considering that the relative importance of the natural sulfur fluxes is likely to increase due to legislation to “clean up” anthropogenic emissions. The largest estimated differences are in the Southern Ocean, Indian Ocean, and parts of the Pacific Ocean, where the climatologies differ in seasonal concentrations over large geographical areas. The model results also indicate that the former DMS climatology underestimated the effect of DMS on the globally averaged annual aerosol radiative forcing at the top of the atmosphere by about 20%, The Indian Institute of Tropical Meteorology is supported by the Ministry of Earth Sciences, Government of India. S.-J.R. and R.S. acknowledge support from the former Spanish Ministry of Science and Innovation through projects PRISMA and Malaspina 2010

In this chapter, we explore the existing trends in the field of cognitive dual satellite systems (DSS). The cognition in DSS is studied via a proposed cognitive cycle to emphasis upon “brain-empowered” communication. A concrete mapping between the phases of cognitive cycle and the phases of engineering design applied in DSS is also proposed thereby bridging the gap between the abstract and the practical implementation of cognitive techniques. The design of cognitive DSS relies on the system and channel modeling to well-assess the external environment. Hence, this chapter provides an extensive account of models of cognitive DSS for both fixed satellite services and land mobile scenarios. In light of these models, we also present an elaborate taxonomy of cognitive techniques in DSS. This chapter serves as an overview for DSS and applicability of cognition in DSS. It also throws light upon open problems for future research.

The recent increase in demand of high quality video applications over satellite channels has led to widespread research in optimal usage of resources to support the user requirements. Particularly, the satellite links are time varying and hence it is beneficial to adapt the rate of transmission across these links by cross-layer optimization techniques (CL). For video applications, it is required to optimize the transmission rate based on providing maximal data rate, for a high definition video, and also maximize the flow continuity of the video, thereby providing minimal freezing of the video during playback. The Quality of Experience (QoE) driven Cross-layer optimization [1], for point-to-point data transmission across satellite networks is one such example of optimizing the video perceived by the user. Another aspect of the satellite systems is the use of satellites as a relay in communication networks. The natural advantage of satellites of covering a huge geographical region leads to a high ubiquity in satellite services, which is particularly advantageous for video transmission. Although use of satellite as a relay between geographically separated terrestrial terminals is imperative, but the same satellite is used as a relay for multiple terminal pairs simultaneously. This leads to multiplexing of resources for transmission at the satellite relay node. This gives the opportunity of network coding at the relay node. A number of recent advances in the field of network coding (NC) have established it as an efficient routing mechanism which can achieve multicast capacity [2]. Implementation of network coding in satellites has also been studied in [3]. The use of NC with CL techniques is imperative to the new generation technologies and has been studied in [4, 5]. In our previous work [6], we have also explored the joint implementation NC with CL over satellite channels. The network coding opportunities are highly maximized with maximal overhearing of unintended packets at different nodes [7]. Otherwise termed as interference, an intelligent treatment of these overheard packets, can lead to an efficient resource utilization [8]. This overhearing is dependent upon the geographical location of the different user terminals [9]. Therefore, the geographical location of users should be considered in order to implement network coding in satellite services [10]. Inspired by these works, in this paper, we present a joint implementation of QoE-driven cross layer optimization and network coding while taking into account the geographical distribution of users in such a way, that the joint scheme improves the overall QoE of the end-user while optimizing the resource utilization. Our work not only admits a flexibility of supporting heterogeneous user demands in terms of video quality, but also allows a uniform maximization of video quality in terms of both clarity and continuity. We consider both the location as well as demand of the user to

In this paper, we address the implementation of physical layer network coding (PNC) based on compute and forward (CF) in relay networks. It is known that the maximum achievable rates in CF-based transmission is limited due to the channel approximations at the relay. In this work, we propose the integer forcing precoder (IFP), which bypasses this maximum rate achievability limitation. Our precoder requires channel state information (CSI) at the transmitter, but only that of the channel between the transmitter and the relay, which is a feasible assumption. The overall contributions of this paper are three-fold. Firstly, we propose an implementation of CF using IFP and prove that this implementation achieves higher rates as compared to traditional relaying schemes. Further, the probability of error from the proposed scheme is shown to have up to 2 dB of gain over the existent lattice network coding-based implementation of CF. Secondly, we analyze the two phases of transmission in the CF scheme, thereby characterizing the end-to-end behavior of the CF and not only one-phase behavior, as in previous proposals. Finally, we develop decoders for both the relay and the destination. We use a generalization of Bezout’s theorem to justify the construction of these decoders. Further, we make an analytical derivation of the end-to-end probability of error for cubic lattices using the proposed scheme.

In this paper, a novel precoding technique is proposed for implementing Physical layer Network Coding (PNC) based on Compute and Forward (CF). In particular, an integer forcing precoder (IFP) is proposed that avoids the maximum rate achievability limitation due to channel approximation at the receiver in previous proposals [4]–[7]. The probability of error from the proposed scheme is shown to have upto 2dB of gain over the existent lattice network coding based implementation of CF. Further, it is shown that the extra power penalty which is paid due to precoding is upper bounded with finite value. It is also shown that the achievable rate using IFP approaches the upper bound for CF. Our precoder requires Channel State Information (CSI) at the transmitter but only that of the channel between the transmitter and relay, which is a feasible assumption.

This study reports on the fabrication of magnetically responsive hollow titania capsules by confining the superparamagnetic Fe(3)O(4) nanoparticles within a hollow and porous titania (TiO(2)) shell. The employed protocol involves precipitation of titania shell on the magnetite (Fe(3)O(4)) encapsulated polystyrene beads followed by the calcination of resulting composite particles at elevated temperature. Scanning electron microscopy and transmission electron microscopy reveal the presence of a thick, complete but irregular titania shell on the magnetic polystyrene beads after the templating process. Electron energy loss mapping image analysis has been employed to investigate the spatial distribution of titania and magnetite phases of magnetic hollow titania capsules (MHTCs). Magnetic characterization indicates that both titania-coated magnetic polystyrene beads (TMPBs) and MHTCs are superparamagnetic in nature with the saturated magnetizations of 5.6 and 8.1 emu/g, respectively. X-ray diffraction (XRD) analysis reveals that titania shell of these capsules is composed of photoactive anatase phase. Nitrogen adsorption-desorption analysis has been employed to estimate the specific surface area and the average pore diameter of the fabricated hollow structures. Photocatalytic activity of the fabricated MHTCs for the photodegradation of rhodamine 6G dye has been demonstrated and compared with that of bulk titania nanoparticles.

Fabrication of organic-inorganic composite particles with tailored size, shape, and morphology has been attracting great attention from researchers because of their fascinating properties and applications in a variety of potential fields. In this study, we report on the fabrication of PS-In(OH)(3) (polystyrene-indium hydroxide) composite particles by hydrolyzing the In(OC(3)H(7))(3) (indium isopropoxide) salt in the presence of beta-diketone functionalized PS colloidal particles. A systematic investigation of the employed reaction conditions allowed us to tune the morphology, size, and In(OH)(3) content of the PS-In(OH)(3) composite particles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results illustrate that variation in the employed concentration of the In(OC(3)H(7))(3) salt in reaction media can effectively tune the morphology of resulting composite particles between "core-shell" and "raspberry-like". X-ray diffraction (XRD) analysis confirms the phase purity of In(OH)(3) nanoparticles precipitated on the surface of PS beads. Colloidal stability of the composite particles has been found to be reduced with increasing the deposited amount of In(OH)(3) nanoparticles. Thermogravimetric analysis (TGA) suggests a continuous increase in the deposited amount of In(OH)(3) nanoparticles with increasing concentration of In(OC(3)H(7))(3) salt in reaction media. The resulting PS-In(OH)(3) composite particles are envisioned to be used in a myriad of potential applications including fabrication of optoelectronic devices, absorption/separation supporting material, catalysts, and hydrophobic surfaces.

A novel and versatile approach for the mixing of ZnO nanofillers into a host polymer matrix, poly(ethyl methacrylate) (PEMA), is reported. Firstly, ZnO nanoparticles are deposited onto the surface of polystyrene (PS) colloidal particles in a "raspberry-like" fashion and subsequently obtained PS/ZnO composite particles are mixed into the PEMA matrix in the range of 0.5 to 5 wt.-%. Microscopic analyses reveal a homogenous distribution of PS/ZnO domains into the PEMA matrix even at 5 wt.-% loading level. Thermogravimetric analysis and differential scanning calorimetry results indicate an improvement in thermal stability of PEMA matrix after mixing with PS/ZnO filler particles. A significant enhancement in mechanical properties of PEMA matrix in the presence of PS/ZnO particles has been evidenced by dynamic mechanical analysis and three point bending measurements.

Sub-micrometer-sized hollow tantalum oxide (Ta2O5) spheres with tunable shell thickness and void size have been fabricated exploiting P-diketone-functionalized polystyrene (PS) beads as sacrificial templates in a sol-gel process. First, a controlled precipitation of Ta2O5 nanoparticles was carried out on the template surface by hydrolyzing tantalum ethoxide (Ta(OEt)(5)) at room temperature, and subsequently, the polymer core was removed either via chemical treatment with toluene or calcination at 650 degrees C. The thickness of the tantala shell precipitated on the PS core during the coating process was tuned between 100 and 142 nm by varying the concentration of tantala precursor in the reaction media. The obtained Ta2O5-coated PS particles and hollow microspheres were characterized by scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. Due to the unique optical and dielectric properties, these nanostructured materials are envisaged to be used in applications such as novel building blocks for the fabrication of advancedmaterials, surface coatings, catalysts, and drug delivery systems. Langmuir

We report on a generic approach for the preparation of ZnO loaded temperature sensitive hybrid microgels with structural hierarchy. The synthetic process involves controlled hydrolysis of Zn(CH(3)COO)(2)center dot 2H(2)O salt in the presence of poly(N-vinylcaprolactam- co-acetoacetoxyethylmethacrylate) (PVCL-AAEM) microgel templates in 2-propanol. Transmission electron microscopy (TEM) and electron mapping image (EMI) analysis have been employed to prove the presence of ZnO nanoparticles inside the polymeric templates. Dynamic light scattering (DLS) measurements reveal that hybrid microgels display a temperature sensitivity similar to the pure template particles, even at a high loading of ZnO nanoparticles. Changes in size, morphology and physical properties of hybrid microgels as a function of the loading amount of ZnO nanoparticles have been discussed. We demonstrate that these nanostructured materials can effectively be used as transparent UV-shielding materials. In addition, these submicrometre-size hybrid microgels could be applied in the fields of optoelectronic devices, UV-detectors, and photocatalysts. Journal of Materials Chemistry

We report on thermo- and pH-responsive copolymer films consisting of N-isopropylacrylamide (NIPAAm) and different carboxyalkylacrylamides exhibiting switchable swelling states over a wide range of temperatures and pH-values. The copolymers were covalently grafted as brush-like films onto solid substrates. Analysis by quartz crystal microbalance with dissipation monitoring revealed the phase transition behaviour to be sensitively controlled by the balance of polar and non-polar interactions, which could be dissected into the local level of comonomer structure as well as the more global level of copolymer chain composition. Remarkably, the phase transition was determined to be in general lower than in solution, which originated from the higher local polymer concentration of the swollen surface-grafted copolymer layer as explained by the general phase behaviour based on classical theory of polymers in solutions. The different swelling profiles of the environmentally responsive copolymer films are expected to offer valuable options for the design of switchable interfaces as, for instance, applicable for the modulation of model biosystems.