Longer Duration Of Time Research Articles

Environmental challenges in the Caspian Sea and international responsibility of its littoral states

The main challenges facing the environment of the Caspian Sea include the water level rise, environmental pollutions, the entrance of exotic species to the Caspian Sea, loss of the flora reservoirs and eutrophication. These challenges forced the coastal states to conclude the Framework Convention on the Protection of the Marine Environment of the Caspian Sea in 2003. The long duration of time taken to adopt this convention and its two protocols, non-significance of two other protocols , the competition over energy issues in the sea and conflict of opinions concerning the legal regime have affected the level of cooperation among five coastal states in this field. This analytical-descriptive study seeks to answer this fundamental question: “What is the responsibility of the Caspian littoral states for environmental damage?” With the reviews, we can say that the Caspian Sea’s coastal states are responsible individually or collectively for their own omission and actions resulting in the environmental damages. They have to recover damages through the restitution or the compensation. It should be noted that the speed up of argument over the legal regime may reduce the environmental problems of the sea.

Integrated Sized-Based Buffer Management Policy for Resource-Constrained Delay Tolerant Network

Delay tolerant network is a type of network where the end-to-end path is not available from source to destination due to the node mobility, dynamic topology and network partitioning or such a path is highly unstable and may split almost immediately after it has been explored. In this background, existing ad hoc routing protocols would be unsuccessful. Therefore, the concept of store-carry-forward mechanism is utilized by introducing a new layer on the top of transport layer called as bundle layer. The bundle layer store message(s) in a finite size buffer for the long duration of time. As a result, node buffer runs out of space and drop messages to overcome congestion. In this paper, we aim to schedule the node buffer by using local knowledge-based buffer management policies called as best message-size selections buffer management policy. We have utilized the local information available in message header such as message-size to control the drop of messages. The evaluation of proposed policy with the existing DOA, DLA, LIFO, MOFO, N-drop and SHLI have been analyzed in ONE simulator in terms of reducing message drop, overhead, latency and raising the delivery ratio.

Detection of Peptides with Different Charges and Lengths by Using the Aerolysin Nanopore

AbstractThe aerolysin nanopore has a high sensitivity for molecular sensing, owing to its super‐narrow diameter and highly charged lumen structure. Here, taking advantages of its high sensitivity, we investigated peptides with comparable size and mass but different charges. Based on the blockade current and duration time, we found that the charge distribution at the entrance of the aerolysin nanopore governs the capture of peptides. Moreover, peptides with the same charge density but different lengths were measured by the aerolysin nanopore. In comparison to the short peptides, longer peptides gave a larger blockade current and a longer duration time. Our findings demonstrate that both the charge and length of peptides affect the translocation process simultaneously, which improve our understanding of peptides’ translocation through the aerolysin nanopore and suggest that aerolysin is an excellent candidate for peptides/protein sequencing.

Headphone listening habits, hearing thresholds and listening levels in Swedish adolescents with severe to profound HL and adolescents with normal hearing

Objective: Research has minimally focussed on the music listening habits and preferred sound volumes among adolescents with severe to profound congenital HL. Listening to music played at loud sound volumes and for a long duration of time could imply risks of worsening the HL. Therefore, it is important to investigate the listening habits in adolescents with HL. The aim of the present study was to describe the use of personal music devices, subjective estimated sound levels, measured sound levels, listening habits, and hearing symptoms in adolescents with severe to profound hearing loss compared with adolescents with normal hearing.Design: The study was conducted in two steps. First, a questionnaire was given to students with or without hearing loss. In step two, hearing and sound level measurements were made in a subsample from both groups.Study sample: The study sample were based on 112 seventeen-year-old students with severe to profound hearing loss and 279 adolescents with normal hearing. Hearing thresholds and listening levels was measured on two subsamples based on 29 adolescents with severe to profound hearing loss and 50 adolescents from the group with normal hearing.Results: The results showed that adolescents with severe to profound hearing loss listened to significantly louder sound levels for longer periods. For both groups, those listening at louder sound levels had poorer hearing thresholds. This finding is especially alarming for subjects with hearing loss. Among those listening above 85 dB per occasion, the sound level ranged between 85.8 dB up to 109 dB for those with hearing loss, whereas the sound level ranged between 85.5 dB and 100 dB for those with normal hearing.Conclusions: Adolescents with congenital hearing loss used portable music devices in the same manner as adolescents with normal hearing. However, adolescents with hearing loss listened to louder sound volumes most likely to compensate for their hearing loss, which significantly increases the risk of further damage to their hearing. From a hearing rehabilitation perspective it could be concluded that aspect of music listening habits should be focussed in order to prevent noise induced hearing loss among individuals with congenital hearing loss.

Modified Light Weight distributed QoS Algorithm for wide area ad hoc networks

SummaryThe direction and velocity of a node are the most important parameters to create a valuable path in ad hoc networks. A valuable path is one that has a longer life time and more durability than others. As we know, the durability of a path is under the influence of the nodes' velocity. This paper proposes an algorithm to provide QoS in ad hoc networks. The proposed algorithm entitled Modified Light Weight distributed QoS Algorithm, considering the direction and relative velocity of the nodes and predicting the value of link durability, chooses a path with longer duration time, minimizes the link breaks, and improves QoSs. We implemented it in a simulation environment by using the Network Simulator Version 2 software and evaluated the effectiveness of it in packet delivery ratio, packet delivery latency, average end‐to‐end delay, routing overhead, and dropped packets. The simulation results demonstrate that Modified Light Weight distributed QoS Algorithm improves the QoS parameters in ad hoc networks.

The Detection Method of Escherichia coli in Water Resources: A Review

This article reviews several approaches for Escherichia coli (E. coli) bacteria detection from conventional methods, emerging method and goes to biosensor-based techniques. Detection and enumeration of E. coli bacteria usually required long duration of time in obtaining the result since laboratory-based approach is normally used in its assessment. It requires 24 hours to 72 hours after sampling to process the culturing samples before results are available. Although faster technique for detecting E. coli in water such as Polymerase Chain Reaction (PCR) and Enzyme-Linked Immunosorbent Assay (ELISA) have been developed, it still required transporting the samples from water resources to the laboratory, high-cost, complicated equipment usage, complex procedures, as well as the requirement of skilled specialist to cope with the complexity which limit their wide spread practice in water quality detection. Recently, development of biosensor device that is easy to perform, portable, highly sensitive and selective becomes indispensable in detecting extremely lower consolidation of pathogenic E. coli bacteria in water samples.

Developing natural lakes for socio-economic development: the case of Nike lake Enugu state, Nigeria

The study examined the potentials and viability of Nike Lake, Enugu state for sustainable economic development in Enugu East Local Government area and its environs. The Nike Lake was purposively selected based on the location attributes and the potentials as identified during the reconnaissance survey. Data collection was through interviews and visitors’ records from Nike resort hotel registry. The level of accommodation patronage was also determined through secondary information of the hotel. The findings clearly show a fluctuation and unstable trend within the years under consideration (2011 and 2016). The study observed that if the resort is fully developed, packaged and advertised, there would be a rapid influx of visitors who would viz-a-vis boosts the socio-economic advancement of the state. Furthermore, it was discovered from the study population that the utilization of Nike lake resort is basically for film shooting, leisure and the snapping of pictures. This represented 30, 20 and 16% respectively. However, 76% of the visitors rated the lake hotel as not good and efficient to attract much economic activity as there were no events that could hold visitors for a long duration of time within the resort. Meanwhile, the study also established that lake resorts are vital tourist resource or asset that can be used to promote tourism at any destination and as such efforts must be made to develop and promote lake resorts in Nigeria.

Modeling of Return Strokes With Their Initiation Processes Under Consideration

We developed an engineering return-stroke model specifically for studying the effects of return-stroke initiation processes. In the model, two current waves with identical wave shapes propagate upward and downward at two independent speeds from a height-variable return-stroke initiation point. Using that model and several results recently observed on the lightning return-stroke initiation processes, we have studied the electromagnetic fields produced by a return stroke at a horizontal distance from the strike termination point. It is shown that, depending on the front steepness of the current waveform, the presence of the downward return-stroke current wave may result in a visible initial peak in the rising portion of the return-stroke-produced field waveforms. A larger initiation height appears to result in an initial field peak with a larger amplitude, and also longer duration time. Moreover, a larger downward return-stroke speed tends to produce a sharper initial field peak.

Analysis of some reliability measures of single-unit systems subject to abnormal environmental conditions and arbitrary distribution for failure and repair activities

This article analyzes the effect of abnormal environmental conditions on various reliability measures. After the continuous operation of single-unit systems for a long duration of time these systems cannot be restored again in a younger state after the failure of the system. The unit does not remain as new after repair. This phenomenon is known as degradation and the unit after repair is called degraded unit. Preventive maintenance is a proactive method to tackle and overcome from these types of problems. For this purpose, a stochastic model is developed for single-unit systems by using semi-Markov process. There is a single server who inspects the failed unit after failed to check the feasibility of repair and replacement. If repair is not feasible then unit is replaced with some replacement time. The failed unit after repair becomes degraded and degraded failed unit is replaced by new one. All time distributions are arbitrary distributed like Weibull distribution with common shape parameter and different scale parameters. The switching devices are instantaneous. The system is observed at suitable regenerative epochs to obtain various measures of system effectiveness of interest to system designers and operation managers.

The JCMT Transient Survey: Stochastic and Secular Variability of Protostars and Disks In the Submillimeter Region Observed over 18 Months

Abstract We analyze results from the first 18 months of monthly submillimeter monitoring of eight star-forming regions in the JCMT Transient Survey. In our search for stochastic variability in 1643 bright peaks, only the previously identified source, EC 53, shows behavior well above the expected measurement uncertainty. Another four sources—two disks and two protostars—show moderately enhanced standard deviations in brightness, as expected for stochastic variables. For the two protostars, this apparent variability is the result of single epochs that are much brighter than the mean. In our search for secular brightness variations that are linear in time, we measure the fractional brightness change per year for 150 bright peaks, 50 of which are protostellar. The ensemble distribution of slopes is well fit by a normal distribution with σ ∼ 0.023. Most sources are not rapidly brightening or fading at submillimeter wavelengths. Comparison against time-randomized realizations shows that the width of the distribution is dominated by the uncertainty in the individual brightness measurements of the sources. A toy model for secular variability reveals that an underlying Gaussian distribution of linear fractional brightness change σ = 0.005 would be unobservable in the present sample, whereas an underlying distribution with σ = 0.02 is ruled out. Five protostellar sources, 10% of the protostellar sample, are found to have robust secular measures deviating from a constant flux. The sensitivity to secular brightness variations will improve significantly with a sample over a longer time duration, with an improvement by factor of two expected by the conclusion of our 36 month survey.

Multi-constraints reliable multicast routing protocol for group communications in MANETs

Mobile ad hoc network (MANET) is a distributed wireless network with highly dynamic topology. So, the nodes keep moving in and out of the network instantly. A path formed between two distant nodes through several intermediate nodes cannot be maintained for a long duration of time. But, the availability of the link between any two nodes can be predicted up to a certain extent by using the available resources in the network, such as the power, bandwidth and delay, etc. Even then the guaranteed data delivery through the path cannot be made. Therefore, reliable multicast routing in MANET is a challenging issue. Thus, in this paper, we have proposed to design a multi-constrained reliable multicast routing protocol (MRMRP) using network coding. This technique builds the reliable path between the source and a multicast receivers. The reliable path between the nodes will be constructed by estimating residual power,bandwidth and delay then network coding scheme is used to recover the lost packet during data transmission. Results of our experiments show the performance improvements in terms of Quality of Service (QoS) metrics such as end-to-end delay, control overhead, packet loss and delivery ratio in comparison with an MAODV and routing technique proposed by Chi et al.

Dynamic Clustering and Cluster Head Selection for Energy Optimization under Wireless Sensor Network

Wireless sensor network is a field of networking that has been used for sensing information from environment. In WSN the sensor nodes are attached to a battery for sensing information. Each node utilizes three types of energy during its lifetime over the network. These energies are sensing energy, transmission or receiving energy and idle energy. During the sensing information the nodes consumes energy and transmission energy is used to transmit a data over a distance. Idle energy is that when node is not working but remains in on state. Due to deployment of WSN in unreachable area energy is main constraint for network to be cost effective.The major issue is network lifetime that must be increase so that network performs for long duration of time and provide cost effective for an n organization. To overcome this issue various methods had been proposed, chaining, pegasis, clustering and chain head selection are one of these methods.

Vesicular Systems Containing Curcumin and Their Applications in Respiratory Disorders - A Mini Review.

Vesicular systems like nanotechnology and liposomes are gaining tremendous attention lately in the field of respiratory diseases. These formulations enhance bioavailability of the drug candidate, which could be achieved through a novel drug delivery mechanism. Moreover, the therapeutic potential achieved through these systems is highly controllable over long durations of time providing better efficacy and patient compliance. The objective of this paper is to review the recent literature on vesicular drug delivery systems containing curcumin. We have collated and summarized various recent attempts made to develop different controlled release drug delivery systems containing curcumin which would be of great interest for herbal, formulation and biological scientists. There are several vesicular nanotechnological techniques involving curcumin which have been studied recently, targeting pulmonary diseases. Different vesicular systems containing curcumin are being studied for their therapeutic potential in different respiratory diseases. There has been a renewed interest in formulations containing curcumin recently, primarily owing to the broad spectrum therapeutic potential of this miracle substance. Various types of formulations, containing curcumin, targeting different bodily systems have recently emerged and, nevertheless, the search for newer frontiers with this drug goes on. This mini review, in this direction, tries to highlight the key research interventions employing vesicular systems of drug delivery with curcumin.

Mechanical behavior of FRP confined steel tubular columns under impact

This paper presents experimental and analytical results of fiber reinforced polymer (FRP) confined steel tubular columns under transverse impact loads. Influences of applied impact energy, thickness of FRP jacket and impact position were discussed in detail, and then the impact responses of FRP confined steel tubes were compared with bare steel tubes. The test results revealed that the FRP jacket contributes to prevent outward buckling deformation of steel at the clamped end and inward buckling of steel at the impact position. For the given applied impact energy, specimens wrapped with one layer and three layers of FRP have the lower peak impact loads than those of the bare steel tubes, whereas specimens wrapped with five layers of FRP exhibit the higher peak impact loads. All the FRP confined steel tubular specimens displayed a longer duration time than the bare steel tubes under the same magnitude of impact energy, and the specimen wrapped with one layer of FRP had the longest duration time. In addition, increasing the applied impact energy leads to the increase of peak impact load and duration time, whereas increasing the distance of impact position from the clamped end results in the decrease of peak impact load and the increase of duration time. The dynamic analysis software Abaqus Explicit was used to simulate the mechanical behavior of FRP confined steel tubular columns, and the numerical results agreed well with the test data. Analytical solution for lateral displacement of an equivalent cantilever beam model subjected to impact load was derived out. Comparison of analytical and experimental results shows that the maximum displacement can be precisely predicted by the present theoretical model.

Surface Modification of Zinc Oxide by 3-aminopropyltiethoxysilane and a Comparative Study of Effect of Corrosion on Carbon Steel With Epoxy Containing Graphene Oxide-Zinc Oxide (GO-ZnO) Hybrids

The use of coupling agent, 3-aminopropyltiethoxysilane (APTES) in the silanization reaction with metal oxides plays an important role to ensure that additional chemical modification can successfully be achieved. Studies have shown that introducing metal oxides onto graphene oxide sheets can improve the dispersion of sheets in a polymeric matrix, contributing to its excellent anti-corrosion properties. Hence, two methods of APTES attachment has been explored, where the first method utilizes a reflux process to introduce siloxane bonds to the ZnO NP surface; the latter usesuse of ultrasonication to stimulate the functionalization of ZnO NPs. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) were employed to characterize the APTES-Functionalized ZnO and the precipitation on the surface of GO sheets. The effect of GO-ZnO produced by the different types of functionalized ZnO on the corrosion protection and barrier performance of epoxy coating was investigated by electrochemical impedence spectroscopy (EIS). The results revealed that the long duration of reaction time provided by the reflux method managed to increase the number of siloxane bonds on the ZnO surface, allowing more amine groups to be attached onto the GO sheets and thus improve the corrosion resistance of epoxy.

Intelligent Scheduling of Thermostatic Devices for Efficient Energy Management in Smart Grid

Residential, commercial, and industrial buildings have been reported to consume a large portion of the generated energy. With the introduction of smart grid and its energy optimization techniques, it is now possible to efficiently manage and control consumers’ energy usage to fulfil their demands with the existing energy generation infrastructure, which otherwise seems to be a backbreaking challenge. This paper presents an efficient energy management solution for buildings with a large number of thermostatic devices (air conditioners) that maintain the temperature of different thermal zones in a predefined range. The primary objective of this paper is to schedule the thermostatic devices in order to reduce total energy consumption by these devices when they are in operation for a very long duration of time, while maintaining the other constraints. We formulate it as a graph problem where minimum mean cycle will provide the desired solution. The proposed methodology ensures that at no point in time the power consumption goes beyond a certain peak power consumption limit. We also enhance the methodology to reduce peak load consumption. Furthermore, a fast greedy approach has been developed to efficiently scale up the aforementioned scheduling scheme for a large number of devices. Experimental results show that significant improvements can be obtained by the proposed approaches over existing algorithms in reducing average energy consumption.

Time-aware service-classified spectrum defragmentation algorithm for flex-grid optical networks

Abstract By employing sophisticated routing and spectrum assignment (RSA) algorithms together with a finer spectrum granularity (namely frequency slot) in resource allocation procedures, flex-grid optical networks can accommodate diverse kinds of services with high spectrum-allocation flexibility and resource-utilization efficiency. However, the continuity and the contiguity constraints in spectrum allocation procedures may always induce some isolated, small-sized, and unoccupied spectral blocks (known as spectrum fragments) in flex-grid optical networks. Although these spectrum fragments are left unoccupied, they can hardly be utilized by the subsequent service requests directly because of their spectral characteristics and the constraints in spectrum allocation. In this way, the existence of spectrum fragments may exhaust the available spectrum resources for a coming service request and thus worsens the networking performance. Therefore, many reactive defragmentation algorithms have been proposed to handle the fragmented spectrum resources via re-optimizing the routing paths and the spectrum resources for the existing services. But the routing-path and the spectrum-resource re-optimization in reactive defragmentation algorithms may possibly disrupt the traffic of the existing services and require extra components. By comparison, some proactive defragmentation algorithms (e.g. fragmentation-aware algorithms) were proposed to suppress spectrum fragments from their generation instead of handling the fragmented spectrum resources. Although these proactive defragmentation algorithms induced no traffic disruption and required no extra components, they always left the generated spectrum fragments unhandled, which greatly affected their efficiency in spectrum defragmentation. In this paper, by comprehensively considering the characteristics of both the reactive and the proactive defragmentation algorithms, we proposed a time-aware service-classified (TASC) spectrum defragmentation algorithm, which simultaneously employed proactive and reactive mechanisms in suppressing spectrum fragments with the awareness of services’ types and their duration times. By dividing the spectrum resources into several flexible groups according to services’ types and limiting both the spectrum allocation and the spectrum re-tuning for a certain service inside one specific spectrum group according to its type, the proposed TASC defragmentation algorithm cannot only suppress spectrum fragments from generation inside each spectrum group, but also handle the fragments generated between two adjacent groups. In this way, the proposed TASC algorithm gains higher efficiency in suppressing spectrum fragments than both the reactive and the proactive defragmentation algorithms. Additionally, as the generation of spectrum fragments is retrained between spectrum groups and the defragmentation procedure is limited inside each spectrum group, the induced traffic disruption for the existing services can be possibly reduced. Besides, the proposed TASC defragmentation algorithm always re-tunes the spectrum resources of the service with the maximum duration time first in spectrum defragmentation procedure, which can further reduce spectrum fragments because of the fact that the services with longer duration times always have higher possibility in inducing spectrum fragments than the services with shorter duration times. The simulation results show that the proposed TASC defragmentation algorithm can significantly reduce the number of the generated spectrum fragments while improving the service blocking performance.

Conductive vancomycin-loaded mesoporous silica polypyrrole-based scaffolds for bone regeneration

Bone tissue engineering is considered an alternative approach for conventional strategies available to treat bone defects. In this study, we have developed bone scaffolds composed of hydroxyapaptite (HAp), gelatin and mesoporous silica, all recognized as promising materials in bone tissue engineering due to favorable biocompatibility, osteoconductivity and drug delivery potential, respectively. These materials were coupled with conductive polypyrrole (PPy) polymer to create a novel bone scaffold for regenerative medicine. Conductive and non-conductive scaffolds were made by slurry casting method and loaded with a model antibiotic, vancomycin (VCM). Their properties were compared in different experiments in which scaffolds containing PPy showed good mechanical properties, higher protein adsorption and higher percentage of VCM release over a long duration of time compared to non-conductive scaffolds. Osteoblast cells were perfectly immersed into the gelatin matrix and remained viable for 14 days. Overall, new conductive composite bone scaffolds were created and the obtained results strongly verified the applicability of this conductive scaffold in drug delivery, encouraging its further development in tissue engineering applications.

Impacts of Summer Extreme Precipitation Events on the Hydrothermal Dynamics of the Active Layer in the Tanggula Permafrost Region on the Qinghai‐Tibetan Plateau

AbstractThe characteristics of long‐term variation for extreme precipitation events were analyzed at the Tanggula site in the continuous permafrost regions of the Qinghai‐Tibetan Plateau (QTP). In addition, the impacts of extreme precipitation events in summer on soil thermal‐moisture dynamics were also investigated. The results showed that local extreme precipitation indices fluctuated significantly and that the trend magnitudes of local very wet days (R95p), annual total wet‐day precipitation (PRCPTOT), number of heavy precipitation days (R10mm), maximum length of dry spell (CDD), and simple daily intensity index (SDII) were larger than those of the western QTP, other regions of China, and even the global average. The freeze‐thaw cycling in the local active layer occurred from October to the next September during 2006 to 2014. The influence of extreme precipitation event in summer on local soil hydrothermal conditions could reach soil depths up to 105 cm or so, and these were more pronounced than with light or moderate precipitation events. Soil temperature reacted more promptly to local extreme precipitation events than did soil moisture. The rate at which local soil temperature fell after an extreme precipitation event was greater than the rate of increasing temperature on nonprecipitation days. Moreover, the amount of precipitation received during extreme precipitation events had a greater effect on local soil moisture and temperature than duration time for these events. Consecutive extreme precipitation events with a longer duration time did not necessarily to have a greater effect than a single precipitation event with a shorter duration. Finally, the thawing process of active layer and local water migration modes could also affect the response of soil hydrothermal conditions to an extreme precipitation event to a large extent.

Chemical engineering of a lipid nano-scaffold for the solubility enhancement of an antihyperlipidaemic drug, simvastatin; preparation, optimization, physicochemical characterization and pharmacodynamic study

This project was designed to extract anti-hyperlipidaemic activity of simvastatin for the longer duration of time and the solubility enhancement of this BCS class II drug was also sought by preparing nanostructured lipid carrier (NLC). The method for NLC preparation involved melt-emulsification followed by ultrasonication. The developed formulation was optimized by 3-level, 3-factor Box–Behnken design. The independent variables were % lipid mixture, % surfactant and sonication time (minutes). The responses selected were particle size, PDI and entrapment efficiency. The optimized formulation had particle size 114.62 ± 5.65, PDI 0.210 ± 0.034 and entrapment efficiency 85.20 ± 7.98%. The optimized formulation was further characterized by TEM and SEM. Spherical shape and nano size distribution of the optimized formulation were confirmed by SEM and TEM, respectively. The DSC of optimized formulation hints for the loss of crystalline nature of drug whereas the FT-IR spectra reveal that there is no interaction between drug and excipients when incorporated in NLC. The drug release from the NLC was biphasic (burst release was followed by sustained release). The kinetic of drug release followed Fickian diffusion with Korsmeyer–Peppas model. When the antihyperlipidaemic activity of SMV-NLC was compared with SMV-suspension, it was found that SMV-NLC significantly decreased the total cholesterol and triglyceride level by 2.77 and threefolds, respectively.