18 resultados para Local and Wide Area Network

em Aston University Research Archive


Relevância:

100.00% 100.00%

Publicador:

Resumo:

B-ISDN is a universal network which supports diverse mixes of service, applications and traffic. ATM has been accepted world-wide as the transport technique for future use in B-ISDN. ATM, being a simple packet oriented transfer technique, provides a flexible means for supporting a continuum of transport rates and is efficient due to possible statistical sharing of network resources by multiple users. In order to fully exploit the potential statistical gain, while at the same time provide diverse service and traffic mixes, an efficient traffic control must be designed. Traffic controls which include congestion and flow control are a fundamental necessity to the success and viability of future B-ISDN. Congestion and flow control is difficult in the broadband environment due to the high speed link, the wide area distance, diverse service requirements and diverse traffic characteristics. Most congestion and flow control approaches in conventional packet switched networks are reactive in nature and are not applicable in the B-ISDN environment. In this research, traffic control procedures mainly based on preventive measures for a private ATM-based network are proposed and their performance evaluated. The various traffic controls include CAC, traffic flow enforcement, priority control and an explicit feedback mechanism. These functions operate at call level and cell level. They are carried out distributively by the end terminals, the network access points and the internal elements of the network. During the connection set-up phase, the CAC decides the acceptance or denial of a connection request and allocates bandwidth to the new connection according to three schemes; peak bit rate, statistical rate and average bit rate. The statistical multiplexing rate is based on a `bufferless fluid flow model' which is simple and robust. The allocation of an average bit rate to data traffic at the expense of delay obviously improves the network bandwidth utilisation.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Target-specific delivery has become an integral area of research in order to increase bioavailability and reduce the toxic effects of drugs. As a drug-delivery option, trigger-release liposomes offer sophisticated targeting and greater control-release capabilities. These are broadly divided into two categories; those that utilise the local environment of the target site where there may be an upregulation in certain enzymes or a change in pH and those liposomes that are triggered by an external physical stimulus such as heat, ultrasound or light. These release mechanisms offer a greater degree of control over when and where the drug is released; furthermore, targeting of diseased tissue is enhanced by incorporation of target-specific components such as antibodies. This review aims to show the development of such trigger release liposome systems and the current research in this field.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

These case studies from CIMA highlight the need to embed risk management within more easily understood behaviours, consistent with the overall organisational culture. In each case, some form of internal audit team provides either an oversight function or acts as an expert link in that feedback loop. Frontline staff, managers and specialists should be completely aligned on risk, in part just to ensure that there is a consistency of approach. They should understand instinctively that good performance includes good risk management. Tesco has continued to thrive during the recession and remains a robust and efficient group of businesses despite the emergence of potential threats around consumer spending and the supply chain. RBS, by contrast, has suffered catastrophic and very public failures of risk management despite a large in-house function and stiff regulation of risk controls. Birmingham City Council, like all local authorities, is adapting to more commercial modes of operation and is facing diverse threats and opportunities emerging as a result of social change. And DCMS, like many other public sector organisations, has to handle an incredibly complex network of delivery partners within the context of a relatively recent overhaul of central government risk management processes. Key Findings: •Risk management is no longer solely a financial discipline, nor is it simply a concern for the internal control function. •Where organisations retain a discrete risk management cadre – often specialists at monitoring and evaluating a range of risks – their success is dependent on embedding risk awareness in the wider culture of the enterprise. •Risk management is most successful when it is explicitly linked to operational performance. •Clear leadership, specific goals, excellent influencing skills and open-mindedness to potential threats and opportunities are essential for effective risk management. •Bureaucratic processes and systems can hamper good risk management – either as a result of a ‘box-ticking mentality’ or because managers and staff believe they do not need to consider risk themselves.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The protection of cyberspace has become one of the highest security priorities of governments worldwide. The EU is not an exception in this context, given its rapidly developing cyber security policy. Since the 1990s, we could observe the creation of three broad areas of policy interest: cyber-crime, critical information infrastructures and cyber-defence. One of the main trends transversal to these areas is the importance that the private sector has come to assume within them. In particular in the area of critical information infrastructure protection, the private sector is seen as a key stakeholder, given that it currently operates most infrastructures in this area. As a result of this operative capacity, the private sector has come to be understood as the expert in network and information systems security, whose knowledge is crucial for the regulation of the field. Adopting a Regulatory Capitalism framework, complemented by insights from Network Governance, we can identify the shifting role of the private sector in this field from one of a victim in need of protection in the first phase, to a commercial actor bearing responsibility for ensuring network resilience in the second, to an active policy shaper in the third, participating in the regulation of NIS by providing technical expertise. By drawing insights from the above-mentioned frameworks, we can better understand how private actors are involved in shaping regulatory responses, as well as why they have been incorporated into these regulatory networks.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We have proposed a novel robust inversion-based neurocontroller that searches for the optimal control law by sampling from the estimated Gaussian distribution of the inverse plant model. However, for problems involving the prediction of continuous variables, a Gaussian model approximation provides only a very limited description of the properties of the inverse model. This is usually the case for problems in which the mapping to be learned is multi-valued or involves hysteritic transfer characteristics. This often arises in the solution of inverse plant models. In order to obtain a complete description of the inverse model, a more general multicomponent distributions must be modeled. In this paper we test whether our proposed sampling approach can be used when considering an arbitrary conditional probability distributions. These arbitrary distributions will be modeled by a mixture density network. Importance sampling provides a structured and principled approach to constrain the complexity of the search space for the ideal control law. The effectiveness of the importance sampling from an arbitrary conditional probability distribution will be demonstrated using a simple single input single output static nonlinear system with hysteretic characteristics in the inverse plant model.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Feminist Translation Studies: Local and Transnational Perspectives situates feminist translation as political activism. Chapters highlight the multiple agendas and visions of feminist translation and the different political voices and cultural heritages through which it speaks across times and places, addressing the question of how both literary and nonliterary discourses migrate and contribute to local and transnational processes of feminist knowledge building and political activism. This collection does not pursue a narrow, fixed definition of feminism that is based solely on (Eurocentric or West-centric) gender politics—rather, Feminist Translation Studies: Local and Transnational Perspectives seeks to expand our understanding of feminist action not only to include feminist translation as resistance against multiple forms of domination, but also to rethink feminist translation through feminist theories and practices developed in different geohistorical and disciplinary contexts. In so doing, the collection expands the geopolitical, sociocultural and historical scope of the field from different disciplinary perspectives, pointing towards a more transnational, interdisciplinary and overtly political conceptualization of translation studies.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The present thesis investigates targeted (locally and systemically) delivery of a novel group of inhibitors of enzyme transglutaminases (TGs). TGs are a widely distributed group of enzymes that catalyse the formation of isopeptide bonds between the y-carboxamide group of protein-bound glutamines and the a-amino group of protein-bound lysines or polyamines. The first group of the novel inhibitors tested were the tluorescently labelled inhibitors of Factor XIIIa (FXIIIa). These small, non-toxic inhibitors have the potential to prevent stabilisation of thrombi by FXIIIa and consequently increase the natural rate of thrombolysis, in addition it reduces staphylococcal colonisation of catheters by inhibiting their FXIIIa¬mediated cross-linking to blood clot proteins on the central venous catheter (CVCs) surface. The aim of this work was to incorporate the FXIIIa inhibitor either within coating of polyurethane (PU) catheters or to integrate it into silicone catheters, so as to reduce the incidence of thrombotic occlusion and associated bacterial infection in CVCs. The initial work focused on the incorporation of FXIIIa inhibitors within polymeric coatings of PU catheters. After defining the key characteristics desired for an effective polymeric-coating, polyvinylpyrrolidone (PVP), poly(lactic-co-glycolic acid) (PLGA) or their combination were studies as polymers of choice for coating of the catheters_ The coating was conducted by dip-coating method in a polymer solution containing the inhibitor. Upon incubation of the inhibitor-and polymer-coated strips in buffer, PVP was dissolved instantly, generating fast and significant drug release, whilst PLGA did not dissolve, yielding a slow and an insufficient amount of drug release. Nevertheless, the drug release profile was enhanced upon employing a blend solution of PVP and PLGA. The second part of the study was to incorporate the FXIIIa inhibitor into a silicone elastomer; results demonstrated that FXIIIa inhibitor can be incorporated and released from silicone by using citric acid (CA) and sodium bicarbonate (SB) as additives and the drug release rate can be controlled by the amount of incorporated additives in the silicone matrix. Furthermore, it was deemed that the inhibitor was still biologically active subsequent to being released from the silicone elastomer strips. Morphological analysis confirmed the formation of channels and cracks inside the specimens upon the addition of CA and SB. Nevertheless, the tensile strength, in addition to Young's modulus of silicone elastomer strips, decreased constantly with an increasing amount of amalgamated CA/ SB in the formulations. According to our results, incorporation of FXIIIa inhibitor into catheters and other medical implant devices could offer new perspectives in preventing bio-material associated infections and thrombosis. The use of tissue transglutaminase (T02) inhibitor for treating of liver fibrosis was also investigated. Liver fibrosis is characterized by increased synthesis and decreased degradation of the extracellular matrix (ECM). Transglutaminase-mediated covalent cross-linking is involved in the stabilization of ECM in human liver fibrosis. Thus, TG2 inhibitors may be used to counteract the decreased degradation of the ECM. The potential of a liposome based drug delivery system for site specific delivery of the fluorescent TG2 inhibitor into the liver was investigated; results indicated that the TG2 inhibitor can be successfully integrated into liposomes and delivered to the liver, therefore demonstrating that liposomes can be employed for site-specific delivery of TG2 inhibitors into the liver and TG2 inhibitor incorporating liposomes could offer a new approach in treating liver fibrosis and its end stage disease cirrhosis.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Recent work has highlighted the potential of sol-gel-derived calcium silicate glasses for the regeneration or replacement of damaged bone tissue. The work presented herein provides new insight into the processing of bioactive calcia-silica sol-gel foams, and the reaction mechanisms associated with them when immersed in vitro in a simulated body fluid (SBF). Small-angle X-ray scattering and wide-angle X-ray scattering (diffraction) have been used to study the stabilization of these foams via heat treatment, with analogous in situ time-resolved data being gathered for a foam immersed in SBF. During thermal processing, pore sizes have been identified in the range of 16.5-62.0 nm and are only present once foams have been heated to 400 degrees C and above. Calcium nitrate crystallites were present until foams were heated to 600 degrees C; the crystallite size varied from 75 to 145 nm and increased in size with heat treatment up to 300 degrees C, then decreased in size down to 95 rim at 400 degrees C. The in situ time-resolved data show that the average pore diameter decreases as a function of immersion time in SBF, as calcium phosphates grow on the glass surfaces. Over the same time, Bragg peaks indicative of tricalcium phosphate were evident after only 1-h immersion time, and later, hydroxycarbonate apatite was also seen. The hydroxycarbonate apatite appears to have preferred orientation in the (h,k,0) direction.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Many cognitive neuroscience studies show that the ability to attend to and identify global or local information is lateralised between the two hemispheres in the human brain; the left hemisphere is biased towards the local level, whereas the right hemisphere is biased towards the global level. Results of two studies show attention-focused people with a right ear preference (biased towards the left hemisphere) are better at local tasks, whereas people with a left ear preference (biased towards the right hemisphere) are better at more global tasks. In a third study we determined if right hemisphere-biased followers who attend to global stimuli are likely to have a stronger relationship between attention and globally based supervisor ratings of performance. Results provide evidence in support of this hypothesis. Our research supports our model and suggests that the interaction between attention and lateral preference is an important and novel predictor of work-related outcomes. © 2012 Copyright Psychology Press Ltd.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Purpose: Although significant amounts of vertical misalignment could have a noticeable effect on visual performance, there is no conclusive evidence about the effect of very small amount of vertical disparity on stereopsis and binocular vision. Hence, the aim of this study was to investigate the effects of induced vertical disparity on local and global stereopsis at near. Materials and Methods: Ninety participants wearing best-corrected refraction had local and global stereopsis tested with 0.5 and 1.0 prism diopter (Δ) vertical prism in front of their dominant and non-dominant eye in turn. This was compared to local and global stereopsis in the same subjects without vertical prism. Data were analyzed in SPSS.17 software using the independent samples T and the repeated measures ANOVA tests. Results: Induced vertical disparity decreases local and global stereopsis. This reduction is greater when vertical disparity is induced in front of the non-dominant eye and affects global more than local stereopsis. Repeated measures ANOVA showed differences in the mean stereopsis between the different measured states for local and global values. Local stereopsis thresholds were reduced by 10s of arc or less on average with 1.0Δ of induced vertical prism in front of either eye. However, global stereopsis thresholds were reduced by over 100s of arc by the same 1.0Δ of induced vertical prism. Conclusion: Induced vertical disparity affects global stereopsis thresholds by an order of magnitude (or a factor of 10) more than local stereopsis. Hence, using a test that measures global stereopsis such as the TNO is more sensitive to vertical misalignment than a test such as the Stereofly that measures local stereopsis. © 2014 Informa Healthcare USA, Inc. All rights reserved: reproduction in whole or part not permitted.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We analyze the performance through numerical simulations of a new modulation format: serial dark soliton (SDS) for wide-area 100-Gb/s applications. We compare the performance of the SDS with conventional dark soliton, amplitude-modulation phase-shift keying (also known as duobinary), nonreturn-to-zero, and return-to-zero modulation formats, when subjected to typical wide-area-network impairments. We show that the SDS has a strong chromatic dispersion and polarization-mode-dispersion tolerance, while maintaining a compact spectrum suitable for strong filtering requirement in ultradense wavelength-division-multiplexing applications. The SDS can be generated using commercially available components for 40-Gb/s applications and is cost efficient when compared with other 100-Gb/s electrical-time-division-multiplexing systems.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The traffic carried by core optical networks grows at a steady but remarkable pace of 30-40% year-over-year. Optical transmissions and networking advancements continue to satisfy the traffic requirements by delivering the content over the network infrastructure in a cost and energy efficient manner. Such core optical networks serve the information traffic demands in a dynamic way, in response to requirements for shifting of traffics demands, both temporally (day/night) and spatially (business district/residential). However as we are approaching fundamental spectral efficiency limits of singlemode fibers, the scientific community is pursuing recently the development of an innovative, all-optical network architecture introducing the spatial degree of freedom when designing/operating future transport networks. Spacedivision- multiplexing through the use of bundled single mode fibers, and/or multi-core fibers and/or few-mode fibers can offer up to 100-fold capacity increase in future optical networks. The EU INSPACE project is working on the development of a complete spatial-spectral flexible optical networking solution, offering the network ultra-high capacity, flexibility and energy efficiency required to meet the challenges of delivering exponentially growing traffic demands in the internet over the next twenty years. In this paper we will present the motivation and main research activities of the INSPACE consortium towards the realization of the overall project solution. © 2014 Copyright SPIE.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Previous research suggests that changing consumer and producer knowledge structures play a role in market evolution and that the sociocognitive processes of product markets are revealed in the sensemaking stories of market actors that are rebroadcasted in commercial publications. In this article, the authors lend further support to the story-based nature of market sensemaking and the use of the sociocognitive approach in explaining the evolution of high-technology markets. They examine the content (i.e., subject matter or topic) and volume (i.e., the number) of market stories and the extent to which content and volume of market stories evolve as a technology emerges. Data were obtained from a content analysis of 10,412 article abstracts, published in key trade journals, pertaining to Local Area Network (LAN) technologies and spanning the period 1981 to 2000. Hypotheses concerning the evolving nature (content and volume) of market stories in technology evolution are tested. The analysis identified four categories of market stories - technical, product availability, product adoption, and product discontinuation. The findings show that the emerging technology passes initially through a 'technical-intensive' phase whereby technology related stories dominate, through a 'supply-push' phase, in which stories presenting products embracing the technology tend to exceed technical stories while there is a rise in the number of product adoption reference stories, to a 'product-focus' phase, with stories predominantly focusing on product availability. Overall story volume declines when a technology matures as the need for sensemaking reduces. When stories about product discontinuation surface, these signal the decline of current technology. New technologies that fail to maintain the 'product-focus' stage also reflect limited market acceptance. The article also discusses the theoretical and managerial implications of the study's findings. © 2002 Elsevier Science Inc. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Computerised production control developments have concentrated on Manufacturing Resources Planning (MRP II) systems. The literature suggests however, that despite the massive investment in hardware, software and management education, successful implementation of such systems in manufacturing industries has proved difficult. This thesis reviews the development of production planning and control systems, in particular, investigates the causes of failures in implementing MRP/MRP II systems in industrial environments and argues that the centralised and top-down planning structure, as well as the routine operational methodology of such systems, is inherently prone to failure. The thesis reviews the control benefits of cellular manufacturing systems but concludes that in more dynamic manufacturing environments, techniques such as Kanban are inappropriate. The basic shortcomings of MRP II systems are highlighted and a new enhanced operational methodology based on distributed planning and control principles is introduced. Distributed Manufacturing Resources Planning (DMRP), was developed as a capacity sensitive production planning and control solution for cellular manufacturing environments. The system utilises cell based, independently operated MRP II systems, integrated into a plant-wide control system through a Local Area Network. The potential benefits of adopting the system in industrial environments is discussed and the results of computer simulation experiments to compare the performance of the DMRP system against the conventional MRP II systems presented. DMRP methodology is shown to offer significant potential advantages which include ease of implementation, cost effectiveness, capacity sensitivity, shorter manufacturing lead times, lower working in progress levels and improved customer service.