Markov modeling of moving target defense games

We introduce a Markov-model-based framework for Moving Target Defense (MTD) analysis. The framework allows modeling of broad range of MTD strategies, provides general theorems about how the probability of a successful adversary defeating an MTD strategy is related to the amount of time/cost spent by the adversary, and shows how a multi-level composition of MTD strategies can be analyzed by a straightforward combination of the analysis for each one of these strategies. Within the proposed framework we define the concept of security capacity which measures the strength or effectiveness of an MTD strategy: the security capacity depends on MTD specific parameters and more general system parameters. We apply our framework to two concrete MTD strategies

A Rate-Compatible Sphere-Packing Analysis of Feedback Coding with Limited Retransmissions

Recent work by Polyanskiy et al. and Chen et al. has excited new interest in using feedback to approach capacity with low latency. Polyanskiy showed that feedback identifying the first symbol at which decoding is successful allows capacity to be approached with surprisingly low latency. This paper uses Chen's rate-compatible sphere-packing (RCSP) analysis to study what happens when symbols must be transmitted in packets, as with a traditional hybrid ARQ system, and limited to relatively few (six or fewer) incremental transmissions. Numerical optimizations find the series of progressively growing cumulative block lengths that enable RCSP to approach capacity with the minimum possible latency. RCSP analysis shows that five incremental transmissions are sufficient to achieve 92% of capacity with an average block length of fewer than 101 symbols on the AWGN channel with SNR of 2.0 dB. The RCSP analysis provides a decoding error trajectory that specifies the decoding error rate for each cumulative block length. Though RCSP is an idealization, an example tail-biting convolutional code matches the RCSP decoding error trajectory and achieves 91% of capacity with an average block length of 102 symbols on the AWGN channel with SNR of 2.0 dB. We also show how RCSP analysis can be used in cases where packets have deadlines associated with them (leading to an outage probability).Comment: To be published at the 2012 IEEE International Symposium on Information Theory, Cambridge, MA, USA. Updated to incorporate reviewers' comments and add new figure

A new species in the major malaria vector complex sheds light on reticulated species evolution

Complexes of closely related species provide key insights into the rapid and independent evolution of adaptive traits. Here, we described and studied Anopheles fontenillei sp.n., a new species in the Anopheles gambiae complex that we recently discovered in the forested areas of Gabon, Central Africa. Our analysis placed the new taxon in the phylogenetic tree of the An. gambiae complex, revealing important introgression events with other members of the complex. Particularly, we detected recent introgression, with Anopheles gambiae and Anopheles coluzzii, of genes directly involved in vectorial capacity. Moreover, genome analysis of the new species allowed us to clarify the evolutionary history of the 3La inversion. Overall, An. fontenillei sp.n. analysis improved our understanding of the relationship between species within the An. gambiae complex, and provided insight into the evolution of vectorial capacity traits that are relevant for the successful control of malaria in Africa

A South African developmental state: the significance of state capacity

This study uses secondary literature and primary sources to explore the significance of state capacity in proposals to build a South African developmental state. Its main aim is to get a deeper understanding of state capacity as a significant ingredient in building a successful developmental state. The analysis is based on the postulation that no country can successfully build a developmental state without the necessary state capacity. The study surveys the literature on developmental states, explores the key attributes/institutional benchmarks of a developmental state and draws out findings about what accounts for a successful developmental state. One of the key conclusions drawn from the literature is that in order for a state to be a successful developmental state, it needs to be institutionally configured in such a way that it possesses the capacity to formulate and implement policies successfully. Using theoretical benchmarks propounded by scholars as a point of reference, the study establishes how we should understand state capacity and shows that such state capacity is a necessary precondition for a successful developmental state. Following from this analysis, it explores how the South African government has to come into grips with the issue of state capacity in its quest to build a South African developmental state. The failure of post-1994 macro and micro economic reform strategies to address the principal challenges of poverty, unemployment and underdevelopment indicates that successful implementation of any policy is dependent on state capacity

Criteria for successful separation by continuous electrophoresis and electrochromatography in blocks and columns

By analysis of some important process variables, criteria for successful separation by continuous electrophoresis and electrochromatography in packed beds are derived. A general theory correlating power input, residence time and temperature rise in cylindrical and rectangular geometries is presented. The limitation of the separating capacity by transverse diffusion effects is shown to be predictable in terms of other operational conditions. These separation criteria appear to be in agreement with experimental evidence, and may find analytical as well as preparative application

Spatially-Coupled Precoded Rateless Codes

Raptor codes are rateless codes that achieve the capacity on the binary erasure channels. However the maximum degree of optimal output degree distribution is unbounded. This leads to a computational complexity problem both at encoders and decoders. Aref and Urbanke investigated the potential advantage of universal achieving-capacity property of proposed spatially-coupled (SC) low-density generator matrix (LDGM) codes. However the decoding error probability of SC-LDGM codes is bounded away from 0. In this paper, we investigate SC-LDGM codes concatenated with SC low-density parity-check codes. The proposed codes can be regarded as SC Hsu-Anastasopoulos rateless codes. We derive a lower bound of the asymptotic overhead from stability analysis for successful decoding by density evolution. The numerical calculation reveals that the lower bound is tight. We observe that with a sufficiently large number of information bits, the asymptotic overhead and the decoding error rate approach 0 with bounded maximum degree

Implementing change in primary care practice: lessons from a mixed-methods evaluation of a frailty initiative

© 2018, BJGP Open. Background: The NHS is facing increasing needs from an aging population, which is acutely visible in the emerging problem of frailty. There is growing evidence describing new models of care for people living with frailty, but a lack of evidence on successful implementation of these complex interventions at the practice level. Aim: This study aimed to determine what factors enable or prevent implementation of a wholesystem, complex intervention for managing frailty (the PACT initiative) in the UK primary care setting. Design & setting: A mixed-methods evaluation study undertaken within a large clinical commissioning group (CCG). Design and analysis was informed by normalisation process theory (NPT). Method: Data collection from six sites included: observation of delivery, interviews with staff, and an online survey. NPT-informed analysis sought to identify enablers and barriers to implementation of change. Results: Seven themes were identified. PACT was valued by professionals and patients but a lack of clarity on its aims was identified as a barrier to implementation. Successful implementation relied on champions pushing the work forward, and dealing with unanticipated resistance. Contracts focused on delivery of service outcomes, but these were sometimes at odds with professional priorities. Implementation followed evidence-informed rather than evidence-based practice, requiring redesign of the intervention and potentially created a new body of knowledge on managing frailty. Conclusion: Successful implementation of complex interventions in primary care need inbuilt capacity for flexibility and adaptability, requiring expertise as well as evidence. Professionals need to be supported to translate innovative practice into practice-based evidence

Exploring experiences in peer mentoring as a strategy for capacity building in sexual reproductive health and HIV service integration in Kenya.

BACKGROUND: The Integra Initiative designed, tested, and adapted protocols for peer mentorship in order to improve service providers' skills, knowledge, and capacity to provide quality integrated HIV and sexual and reproductive health (SRH) services. This paper describes providers' experiences in mentoring as a method of capacity building. Service providers who were skilled in the provision of FP or PNC services were selected to undergo a mentorship training program and to subsequently build the capacity of their peers in SRH-HIV integration. METHODS: A qualitative assessment was conducted to assess provider experiences and perceptions about peer mentoring. In-depth interviews were conducted with twelve mentors and twenty-three mentees who were trained in SRH and HIV integration. Interviews were recorded, transcribed, and imported to NVivo 9 for analysis. Thematic analysis methods were used to develop a coding framework from the research questions and other emerging themes. RESULTS: Mentorship was perceived as a feasible and acceptable method of training among mentors and mentees. Both mentors and mentees agreed that the success of peer mentoring largely depended on cordial relationship and consensus to work together to achieve a specific set of skills. Mentees reported improved knowledge, skills, self-confidence, and team work in delivering integrated SRH and HIV services as benefits associated with mentoring. They also associated mentoring with an increase in the range of services available and the number of clients seeking those services. Successful mentorship was conditional upon facility management support, sufficient supplies and commodities, a positive work environment, and mentors selection. CONCLUSION: Mentoring was perceived by both mentors and mentees as a sustainable method for capacity building, which increased providers' ability to offer a wide range of and improved access to integrated SRH and HIV services

Absorptive capacity and knowledge transfer : an exploratory model for university-led research institutes (RIs) and small and medium enterprises (SMEs) : a 152.800 thesis presented in partial fulfilment of the requirements of the degree of Masters of Business Studies in Management at Massey University

'Absorptive capacity' is a construct used to define an organisation's ability to exploit knowledge that is available internally and externally. The construct is very popular within management research and has been used to describe the absorptive capacity of a range of strategic Multinational Corporation partners through to whole regions of countries. SMEs account for over 95% of businesses throughout the world. They provide innovation, productivity and economic growth, but because of their size and resources cannot afford to carry out costly Research and Development (R&D). They therefore need to be able to harness the intellectual property from universities through University-led Research institutes. This thesis uses the construct of absorptive capacity to propose a theoretical model to analyse the knowledge transfer from a University-led Research Institute (RI) to an SME, when the SME is commercialising a product or process the RI has developed. The application of absorptive capacity in this context would allow SME researchers and managers to develop understanding of how this knowledge transfer is affected by internal and external factors. The importance of continued government funding to ensure the collaboration between SMEs and RIs is highlighted. This research design is highly exploratory resulting in a range of future research suggestions for future hypothesis generation. Most important of these are suggestions for determining, defining and developing the organisational determinants of absorptive capacity. This will allow a prescriptive analysis of how knowledge transfer occurs between the SME and RI and how managers can foster organisational absorptive capacity for successful knowledge transfer. Additionally, the temporal aspect of the SME and RI relationship could be explored, such as the impact of the initial experience on the ease and length of future knowledge transfer relationships. Also, researchers could study the change in the SME's knowledge requirements from the RI as the SME's organisational structure grows

Expanding taxable capacity and reaching revenue potential : cross-country analysis

An effective tax system is fundamental for successful country development. The first step to understand public revenue systems is to establish some commonly agreed performance measurements and benchmarks. This paper employs a cross-country study to estimate tax capacity from a sample of 104 countries during 1994-2003. The estimation results are then used as benchmarks to compare taxable capacity and tax effort in different countries. Taxable capacity refersto the predicted tax-gross domestic product ratio that can be estimated with the regression, taking into account a country's specific economic, demographic, and institutional features. Tax effort is defined as an index of the ratio between the share of the actual tax collection in gross domestic product and the predicted taxable capacity. The authors classify countries into four distinct groups by their level of actual tax collection and attained tax effort. This classification is based on the benchmark of the global average of tax collection and a tax effort index of 1 (when tax collection is exactly the same as the estimated taxable capacity). The analysis provides guidance for countries with various levels of tax collection and tax effort.Taxation&Subsidies,Debt Markets,Public Sector Economics&Finance,Emerging Markets,Economic Theory&Research