934 resultados para distributed denial-of-service attack


Relevância:

100.00% 100.00%

Publicador:

Resumo:

This article uses a qualitative approach to elicit the views of 31 professionals who provide services to vulnerable young men. The findings reveal six key themes following focus group interviews: (i) the importance of masculinity in explaining problematic behaviour; (ii) the misuse of alcohol and drugs; (iii) alienation and social isolation; (iv) concerns about suicide and self-harm; (v) the quality of existing services; and (vi) recommendations for changes to services. Service providers generally acknowledged the social context in explaining these behaviours and argued for enhanced services and a more developed skills base in working with vulnerable young men. 

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We present a mathematically rigorous Quality-of-Service (QoS) metric which relates the achievable quality of service metric (QoS) for a real-time analytics service to the server energy cost of offering the service. Using a new iso-QoS evaluation methodology, we scale server resources to meet QoS targets and directly rank the servers in terms of their energy-efficiency and by extension cost of ownership. Our metric and method are platform-independent and enable fair comparison of datacenter compute servers with significant architectural diversity, including micro-servers. We deploy our metric and methodology to compare three servers running financial option pricing workloads on real-life market data. We find that server ranking is sensitive to data inputs and desired QoS level and that although scale-out micro-servers can be up to two times more energy-efficient than conventional heavyweight servers for the same target QoS, they are still six times less energy efficient than high-performance computational accelerators.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Interesting wireless networking scenarios exist wherein network services must be guaranteed in a dynamic fashion for some priority users. For example, in disaster recovery, members need to be able to quickly block other users in order to gain sole use of the radio channel. As it is not always feasible to physically switch off other users, we propose a new approach, termed selective packet destruction (SPD) to ensure service for priority users. A testbed for SPD has been created, based on the Rice University Wireless open-Access Research Platform and been used to examine the feasibility of our approach. Results from the testbed are presented to demonstrate the feasibility of SPD and show how a balance between performance and acknowledgement destruction rate can be achieved. A 90% reduction in TCP & UDP traffic is achieved for a 75% MAC ACK destruction rate.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The alkali activation of waste products has become a widespread topic of research, mainly due to environmental benefits. Portland cement and alkali-activated mortar samples were prepared to compare their resistance to silage effluent which contains lactic acid. The mechanism of attack on each sample has also been investigated.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Service user and carer involvement (SUCI) in social work education in England is required by the profession’s regulator, the Health and Care Professions Council. However, a recent study of 83 HEIs in England reported that despite considerable progress in SUCI, there is no evidence that the learning derived from it is being transferred to social work practice. In this article we describe a study that examines the question: ‘What impact does SUCI have on the skills, knowledge and values of student social workers at the point of qualification and beyond?’ Students at universities in England and Northern Ireland completed online questionnaires and participated in focus groups, spanning a period immediately pre-qualification and between six to nine months post-qualification. From our findings, we identify four categories that influence the impact of service user involvement on students’ learning: student factors; service user and carer factors; programme factors; and practice factors; each comprises of a number of sub-categories. We propose that the model developed can be used by social work educators, service user and carer contributors and practitioners to maximise the impact of SUCI. We argue that our findings also have implications for employment-based learning routes and post-qualifying education.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Chloride-induced corrosion of steel in reinforced concrete structures is one of the main problems affecting their durability, but most previous research projects and case studies have focused on concretes without cracks or not subjected to any structural load. Although it has been recognised that structural cracks do influence the chloride transport and chloride induced corrosion in reinforced concrete structures, there is little published work on the influence of micro-cracks due to service loads on these properties. Therefore the effect of micro-cracks caused by loading on chloride transport into concrete was studied. Four different stress levels (0%, 25%, 50% and 75% of the stress at ultimate load – fu) were applied to 100 mm diameter concrete discs and chloride migration was measured using a bespoke test setup based on the NT BUILD 492 test. The effects of replacing Portland cement CEMI by ground granulated blast-furnace slag (GGBS), pulverised fuel ash (PFA) and silica fume (SF) on chloride transport in concrete under sustained loading were studied. The results have indicated that chloride migration coefficients changed little when the stress level was below 50% of the fu; however, it is desirable to keep concrete stress less than 25% fu if this is practical. The effect of removing the load on the change of chloride migration coefficient was also studied. A recovery of around 50% of the increased chloride migration coefficient was found in the case of concretes subjected to 75% of the fu when the load was removed.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The modulation of neural activity in visual cortex is thought to be a key mechanism of visual attention. The investigation of attentional modulation in high-level visual areas, however, is hampered by the lack of clear tuning or contrast response functions. In the present functional magnetic resonance imaging study we therefore systematically assessed how small voxel-wise biases in object preference across hundreds of voxels in the lateral occipital complex were affected when attention was directed to objects. We found that the strength of attentional modulation depended on a voxel's object preference in the absence of attention, a pattern indicative of an amplificatory mechanism. Our results show that such attentional modulation effectively increased the mutual information between voxel responses and object identity. Further, these local modulatory effects led to improved information-based object readout at the level of multi-voxel activation patterns and to an increased reproducibility of these patterns across repeated presentations. We conclude that attentional modulation enhances object coding in local and distributed object representations of the lateral occipital complex.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Tese dout., Engenharia Electrónica e Computação, Universidade do Algarve, 2009

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This book gives the history of the South Carolina Chapter 61 of the Telephone Pioneers of America from 1960-2010. These volunteers repair talking book machines for the South Carolina State Library Talking Book Services.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Research on how customers engage in the co-creation processes envisaged by the Servicedominant logic paradigm is currently limited and even less work has been published on frameworks for organizations to manage the co-creation process. This conceptual paper examines a particular aspect of co-creation: co-production as a result of the application of self-service technology (SST). We propose a conceptual framework for co-production, which emphasizes the need to understand productivity from the point of view of the customer, and demonstrate how this can be applied in both consumer (b2c) and interorganizational(b2b) contexts. We conclude that service organizations might benefit from clearly identifying co-production with task-performance, and co-creation with the valueattributing aspects of the customer service experience. Both aspects generate a range of design and management challenges for suppliers particularly the need to understand the cocreation process 'outputs' desired by customers and the full costs of moving away from person to person interaction.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Wireless sensor networks (WSNs) emerge as underlying infrastructures for new classes of large-scale networked embedded systems. However, WSNs system designers must fulfill the quality-of-service (QoS) requirements imposed by the applications (and users). Very harsh and dynamic physical environments and extremely limited energy/computing/memory/communication node resources are major obstacles for satisfying QoS metrics such as reliability, timeliness, and system lifetime. The limited communication range of WSN nodes, link asymmetry, and the characteristics of the physical environment lead to a major source of QoS degradation in WSNs-the ldquohidden node problem.rdquo In wireless contention-based medium access control (MAC) protocols, when two nodes that are not visible to each other transmit to a third node that is visible to the former, there will be a collision-called hidden-node or blind collision. This problem greatly impacts network throughput, energy-efficiency and message transfer delays, and the problem dramatically increases with the number of nodes. This paper proposes H-NAMe, a very simple yet extremely efficient hidden-node avoidance mechanism for WSNs. H-NAMe relies on a grouping strategy that splits each cluster of a WSN into disjoint groups of non-hidden nodes that scales to multiple clusters via a cluster grouping strategy that guarantees no interference between overlapping clusters. Importantly, H-NAMe is instantiated in IEEE 802.15.4/ZigBee, which currently are the most widespread communication technologies for WSNs, with only minor add-ons and ensuring backward compatibility with their protocols standards. H-NAMe was implemented and exhaustively tested using an experimental test-bed based on ldquooff-the-shelfrdquo technology, showing that it increases network throughput and transmission success probability up to twice the values obtained without H-NAMe. H-NAMe effectiveness was also demonstrated in a target tracking application with mobile robots - over a WSN deployment.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

IEEE International Conference on Cyber Physical Systems, Networks and Applications (CPSNA'15), Hong Kong, China.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The purpose of this qualitative research study was to foster an understanding of the rehabilitation counselling practice offamilies of the brain-injured. Specifically, the study explores the perceptions of stakeholders in regards to the degree of satisfaction with the quality of service received. Questionnaires were administered, and semi-structured, openended interviews were conducted, with six participating families (n=8). Preliminary data were collected via two instruments: (i) the Family Participant Questionnaire, consisting of participants' sample characteristics, information pertaining to the history of the family, details of the injury, and information relating to the type, use, and need offamily services utilized; and (ii) the Community Integration Questionnaire, a measurement of the degree of social displacementllevel of community integration of the injured family member. Utilizing the procedural steps outlined by Colaizzi's (1978) method of protocol analysis, recommendations for a future program based on related and current family needs are discussed in detail. Substantiating and supporting information are offered to rehabilitation practitioners, educational planners, and policymakers alike, concerning the degree of satisfaction with rehabilitative service, and the means of improving upon the overall quality of health care to families of the brain-injured. Implications for clinical practice and research are also raised for discussion.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The reaction of tris(pentafluorophenyl)phosphine [5] with the nucleophiles dimethyl formamide (DMF), hexamethylphosphoric triamide (HMPA), diethyl formamide (DEF), hexaethylphosphoric triamide (HEPA), hydrazine, N,N-dimethyl hydrazine (in presence and/or absence of KF), phenylhydrazine, ammonium hydroxide, formamide, aniline, sodium hydrogen sulfide, and hexaethylphosphorous triamide was investigated. The reaction of [5] with DMF and HMPA gave the same product, namely tris-[4-(N,N-dimethylamino)-2,3,5,6-tetrafluorophenyl]phosphine [12] but in higher yield in the case of HMPA. Compound (5] also reacted with DEF to give tris[4-(N,N-diethylamino)-2,3,5,6-tetrafluorophenyl] phosphine [14]. When [51 was treated with HEPA, it gave a mixture of bis(pentafluorophe~yl)-(N,N-diethylamino-tetrafluorophenyl)phosphine, pentafluorophenyl-bis-(N,N-diethylamino-tetrafluorophenyl)phosphine and tris (N,N-diethylamino-tetrafluorophenyl)phosphine. Treatment of [5] with aqueeus hydrazine solution in excess ethanol gave tris(4-hydrazo-2,3,4,6-tetrafluorophenyl)phosphine [1s1 in high yield while reaction with aqueous hydrazine led to C-P cleavage and production of tetrafluorophenyl hydrazine. With N,N-dimethyl hydrazine, [5] gave tris(4-N,N-dimethylhydrazine-2,3,5,6-tetrafluorophenyl) phosphine {20j. The latter could be obtained in higher yield and shorter reaction time, by the addition of KF. The reaction of compound {51 with phenylhydrazine in THF gave bis(pentafluorophe~yl)-4-S-phenylhydrazino- 2,3,5,6-tetrafluorophenyl phosphine [22] in low yield. Reaction of [5] with ammonium hydroxide in THF at high pressure in the presence of KF gave tris-~4-amino-2,3,5,6-tetrafluorophenyl)phosphine [25]. Similarly, formamide led to a mixture of (C6F4NHZ)3P, (C6F4NHZ)ZPC6FS, (C6F4NHZ)ZPC6F4NHCHO, and C6F4NHZP(C6Fs)(C6F4NHCHO). When [5] was treated with aniline, a mixture of mono-, di-, and tri-substituted products was obtained. Sodium hydrogen sulfide in ethylene glycol/ pyridine led to C-P cleavage and the isolation of pentafluorobenzene and tetrafluorothiophenol. Reaction of [5] and its oxide [35] with different alkoxides in the corresponding alcohols led mainly to C-P bond cleavage products, with the exception of one case where sodium methoxide was used in ether, and which led to tris-(4-methoxy-2,3,9,6-tetrafluorophenyl)phosphine [37]. On the basis of various spectroscopic data, it was concluded that the para position in compound [5] was generally the favoured site of attack.