Core Ideas
Hot water extractable and microaggregate C explained 60% of soil C change over time.
Hot water extractable and microaggregate N explained 47% of soil N change over time.
No significant ...soil order effects on changes in C and N in fractions.
Storage of C and N within aggregates is important for long‐term stabilization of soil organic matter (SOM). We investigated whether changes in C and N associated with physical soil fractions and the hot water extractable pool were correlated to changes in topsoil C and N over three decades. Archived soil samples from three soil orders collected from 46 sites across New Zealand were physically fractionated and the aggregate abundance (and C and N contents) of fractions determined; hot water extractable C (HWC) and hot water extractable N (HWN) were also measured. Together the change of C and N in hot water extractable SOM, microaggregate within macroaggregate, and free microaggregate fractions explained 60 and 47% of the change in whole soil C and N, respectively. Soil order was not a significant factor in the model suggesting that similar processes were operating in all three soil types. In summary, the development of strategies that enhance the storage of labile SOM and microaggregates could reverse the trend of loss of SOM and its associated ecosystems services.
Summary
The mobile cloud computing (MCC) has enriched the quality of services that the clients access from remote cloud‐based servers. The growth in the number of wireless users for MCC has further ...augmented the requirement for a robust and efficient authenticated key agreement mechanism. Formerly, the users would access cloud services from various cloud‐based service providers and authenticate one another only after communicating with the trusted third party (TTP). This requirement for the clients to access the TTP during each mutual authentication session, in earlier schemes, contributes to the redundant latency overheads for the protocol. Recently, Tsai et al have presented a bilinear pairing based multi‐server authentication (MSA) protocol, to bypass the TTP, at least during mutual authentication. The scheme construction works fine, as far as the elimination of TTP involvement for authentication has been concerned. However, Tsai et al scheme has been found vulnerable to server spoofing attack and desynchronization attack, and lacks smart card‐based user verification, which renders the protocol inapt for practical implementation in different access networks. Hence, we have proposed an improved model designed with bilinear pairing operations, countering the identified threats as posed to Tsai scheme. Additionally, the proposed scheme is backed up by performance evaluation and formal security analysis.
Recently, Tsai et al have presented a bilinear‐pairing based multi‐server authentication (MSA) protocol, to eliminate the involvement of trusted third party from mutual authentication. However, the scheme has been found vulnerable to server spoofing attack and desynchronization attacks. It also lacks smart card‐based user verification, which renders the protocol inapplicable for practical deployment. Hence, we have proposed an improved model, countering the identified threats as posed to Tsai scheme. Moreover, our scheme is backed up by performance evaluation and formal security analysis.
Nitrification inhibitors, such as dicyandiamide (DCD), have been shown to decrease leaching from urea- and ammonium-based fertilisers and from urine patches in grazed pastures. To date there have ...been few studies on effects of nitrification inhibitors on non-target soil microbiota. This pot trial examined the short-term effects of DCD on the activity and diversity of both target (ammonium-oxidising bacteria and archaea) and non-target soil microbial populations. Bovine urine at a rate equivalent to 600kgurine-Nha−1 with or without DCD at 30kgha−1 was applied to pots planted with perennial ryegrass. This rate of DCD was typical of the amount applied to pasture in New Zealand, although this annual rate may be spread over several applications carried out over 2–3 months. The single high rate application was used to provide a “worst case scenario” to assist detection of potential impacts of DCD application to non-target soil microflora. Treatments also included DCD alone and untreated control pots. Soil used was a Horotiu sandy loam and pots were maintained at 80% WHC in a controlled-environment room at 12°C/16h (day) and 8°C/8h (night). Soil mineral N, hot water extractable C and N concentrations, soil pH, microbial biomass C and N, and DCD persistence were measured at regular intervals. Diversity and composition of the overall soil bacterial community were analysed by serial analysis of ribosomal sequence tags (SARST). Effects on ammonium-oxidising bacterial and archaeal communities were monitored more closely by determining the size of these populations using real-time PCR and their transcriptional activity by comparing RNA-denaturing gradient gel electrophoresis (DGGE) profiles following RT-PCR of the amoA gene. Changes in soil pH and mineral N following application of urine in the pot trial reflected patterns typically demonstrated in the field. Application of DCD to soil did not change the diversity of the soil bacterial community, with the four predominant phyla (Proteobacteria, Actinobacteria, Acidobacteria and Firmicutes) remaining in proportions that were similar to control soils. In contrast, urine application to soil resulted in a significant increase in members of Firmicutes, some of which are relatively stress tolerant. In line with the SARST results, shifts in the structure of the active component of the general soil bacterial community were detected in the urine and urine+DCD treatments only, further suggesting DCD had little impact on the overall soil bacterial activity. In contrast the microbes targeted by DCD, the ammonium-oxidising bacteria, were significantly affected by DCD with reductions in population size and altered activity. Ammonium-oxidising archaea, however, showed no response to application of DCD to soil, and were only minimally affected by application of urine. The results suggest that application of DCD to pasture is a relatively benign intervention that has an important role to play in mitigating the environmental hazards imposed by ongoing land use intensification.
Sign languages are a fundamental source of communication for the deaf community, generated through movements of the human body. Similar to the natural languages, sign languages vary from region to ...region, and from nation to nation. Pakistan sign language (PSL) is inspired by Urdu, national language of Pakistan. It has 38 alphabet signs, and out of them, 36 are represented by the static hand gestures. Automatic recognition of a sign language helps in interaction between the hearing and deaf individuals. The number of quality efforts in context of Pakistan sign language recognition is quite limited, leaving a fair room for addressing open issues of research, i.e., (i) efficient hand detection under complex backgrounds and (ii) extracting signer independent feature vector that should not only be discriminant for all the PSL alphabets but reduced dimension as well. In this research, recognition of PSL static alphabets is addressed where the task of hand localization is accomplished through faster regional-convolutional neural networks (faster R-CNN). Feature extraction is achieved through presenting symmetric mean-based binary patterns (sMBP) that extend uniform local binary patterns. The proposed feature vector not only suppresses the noise but preserves the rotation invariance as well. Classification task is accomplished through error correction output codes (ECOC)-based support vector machines using linear, polynomial and radial basis function kernels with one-vs-one and one-vs-all modalities. The proposed technique is validated through PSL dataset, created by seven native signers, having 7174 images. The comparative results clearly demonstrate the authority of the proposed technique over all of its baseline and competitor techniques.
Many Internet of Things (IoT) applications have been developed and implemented on unreliable wireless networks like the delay tolerant network (DTN); however, efficient data transfer in DTN is still ...an important issue for the IoT applications. One of the application areas of DTN is vehicular delay tolerant network (VDTN) where the network faces communication disruption due to lack of end‐to‐end relay route. It is challenging as some of the nodes show selfish behavior to preserve their resources like memory and energy and become noncooperative. In this article, an honesty‐based democratic scheme (HBDS) is introduced where vehicles with higher honesty level are elected as heads—during the process. Vehicles involved in the process would maximize their rewards (reputation) through active participation in the network activities, whereas vehicles with noncooperative selfish behavior are punished. The honesty level of the heads is analyzed using Vickrey, Clarke, and Groves (VCG) model. The mathematical model and algorithms developed in the proposed HBDS technique are simulated using the VDTNSim framework to evaluate their efficiency. The performance results show that the proposed scheme dominates current schemes in terms of packet delivery probability, packet delivery delay, number of packets drop, and overhead ratio.
In this article, an honesty‐based democratic scheme (HBDS) is introduced where vehicles with higher honesty level are elected as heads—during the process. Vehicles involved in the process would maximize their rewards (reputation) through active participation in the network activities, whereas vehicles with noncooperative selfish behavior are punished.
Summary
With limited resources, overutilization is a challenging issue in the emerging system of smart devices, resulting in higher costs, poor performance and low prices due to service level ...agreement (SLA) violations. These factors extremely annoy the customers as well as providers. External resources are hired to overcome the resources scalability challenges; however, external resources cause higher delay, running time, and transfer cost. The lift in delay explicitly means more cost and more customers dissatisfaction. The delay and transfer cost increases with geographical distance and overutilization. In this article, a mechanism is proposed to make efficient migration decisions to external cloud service providers (CSPs) to minimize the delay, running time, and transfer cost by searching an optimum data center (DC), where the resources may be taken with optimum conditions. The Cloud Analyst is extended to simulate the proposed framework. Results were calculated for three different phenomena, where hiring the resources from underutilized DC decreases the running time to 0.237 ms; however, the response time and transfer cost increases to 499 ms and 0.228 $, respectively; similarly, getting the resources of nearest DC drops the delay time and transfer cost to 80 ms and 0.065 $ respectively; however, the execution time increases to 0.500 ms. The proposed framework optimized the delay time, execution time and transfer cost to 50 ms, 0.237 ms, and 0.065 $, respectively.
Overutilization with limited resources is a challenging issue in the emerging world of smart devices. In this article, a mechanism is proposed to make efficient migration decisions to external cloud service providers (CSPs) to minimize the delay, running time, and transfer cost. The simulation result shows that delay, running time, and transfer cost is decreased as the CSPs are selected according to the proposed algorithm decisions.
The need for Lightweight cryptography is on the rise as transition has been made from wired to wireless network. Wireless systems inherently are insecure and resource (power) constrained, to deal ...with these constraints, many techniques for symmetric and asymmetric cryptography are defined. One such important developement is Signcryption to achieve message confidentiality, integrity, sender and message authentication, non repudiation, forward secrecy as well as unforgeability,and public verifiability. Since Signcryption combines the signature and encryption therefore the cost is very less in comparison to those schemes based on the signature then encryption. Many signcryption schemes have been proposed based on El-Gamal, RSA and ECC till today. This paper highlights limitations of the existing ECC based schemes using signcryption. These limitations include some missing security aspects as well as high computation power requirement, more communication overhead incurred and large memory requirements. Further it proposes an efficient lightweight signcryption scheme based on HECC which fulfills all the security requirements. The scheme reduced significant amounts of computation, communication costs and message size as compared to existing signcryption schemes making it the good candidate for environments suffer from the resource limitation problems.
This study critically reviews the IaaS clouds development on revenue maximization since 2012 to answer these research queries; (i) What are the main influential factors towards revenue maximization ...in the cloud market? (ii) What are the main challenges and resistance towards revenue maximization in cloud computing? and (iii) What are the possible solutions and potentials to these hurdles in cloud computing? The data was analyzed and the influencing factors of revenue maximization were classified into seven distinct categories, that is, the performance of the services, service level agreement and penalties management, resources scalability, resources utilization and scheduling, customers' satisfaction, cost, and pricing management, as well as advertisement and auction. These parameters are investigated in detail and new dynamics for researchers in the field of the cloud are discovered. These studies are compared against each other for the seven distinct categories and solutions are proposed for the clouds' obstacles to revenue maximization. Furthermore, in the light of the findings and revenue maximization categories, the main limitations, challenges, true potential, and new directions towards revenue maximization are explored.
Main revenue factors are categorized as service level agreement and penalty management, resource scalability, customer satisfaction and management, resource utilization and provision, cost and price management, and advertising and auction. These parameters are investigated in detail and new dynamics for researchers in the field of the cloud are discovered.
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