Consistent SDNs through Network State Fuzzing

The conventional wisdom is that a software-defined network (SDN) operates under the premise that the logically centralized control plane has an accurate representation of the actual data plane state. Nevertheless, bugs, misconfigurations, faults or attacks can introduce inconsistencies that undermine correct operation. Previous work in this area, however, lacks a holistic methodology to tackle this problem and thus, addresses only certain parts of the problem. Yet, the consistency of the overall system is only as good as its least consistent part. Motivated by an analogy of network consistency checking with program testing, we propose to add active probe-based network state fuzzing to our consistency check repertoire. Hereby, our system, PAZZ, combines production traffic with active probes to continuously test if the actual forwarding path and decision elements (on the data plane) correspond to the expected ones (on the control plane). Our insight is that active traffic covers the inconsistency cases beyond the ones identified by passive traffic. PAZZ prototype was built and evaluated on topologies of varying scale and complexity. Our results show that PAZZ requires minimal network resources to detect persistent data plane faults through fuzzing and localize them quickly

Spontaneous and stimulated emission tuning characteristics of a Josephson junction in a microcavity

We have investigated theoretically the tuning characteristics of a Josephson junction within a microcavity for one-photon spontaneous emission and for one-photon and two-photon stimulated emission. For spontaneous emission, we have established the linear relationship between the magnetic induction and the voltage needed to tune the system to emit at resonant frequencies. For stimulated emission, we have found an oscillatory dependence of the emission rate on the initial Cooper pair phase difference and the phase of the applied field. Under specific conditions, we have also calculated the values of the applied radiation amplitude for the first few emission maxima of the system and for the first five junction-cavity resonances for each process. Since the emission of photons can be controlled, it may be possible to use such a system to produce photons on demand. Such sources will have applications in the fields of quantum cryptography, communications and computation

African Traditional Cultural Values and Beliefs: A Driving Force to Natural Resource Management: A Study of Makonde District, Mashonaland West Province, Zimbabwe

Natural resources in Africa are in jeopardy of depletion as a result of increasing demographic pressure and  climate change. Sustainability of the natural resource base can be achieved through adoption of traditional cultural values and beliefs. This research was conducted in Makonde District, Mashonaland West Province of Zimbabwe. The research is qualitative in nature and employs the empirical case study research design through adopting the descriptive approach to data. The research involved description of knowledge, behaviors, perceptions and attitudes of the people in the Makonde District on cultural values and beliefs for the sustainable management of natural resources. The results of the study indicate that cultural norms and values such as totems, taboos, traditional ceremonies, and the formation of the old age group committees as well as the role of the spirit mediums have an impact of the conservation of natural resources namely tree species, water resources, forests, minerals and some sacred groves in Makonde district. Therefore, we recommend that traditional leaders should be a vital cog whenever natural resources management policy is crafted by central government. We also recommend cultural values and belief should be integrated into the development plans of the country. Keywords: natural  resources management, cultural values, beliefs, sustainabilit

Medical device innovation in South Africa: Evolution of collaboration networks (2001-2013)

The evolution of medical device development in South Africa was investigated for the period 2001-2013. Collaboration networks for four sectors - academia, healthcare, industry, and science and support - were derived from a bibliometric study. Centrality measures identified dominant institutions. New actors entering the networks either exhibited preferential attachment to these institutions, or joined the network as part of an isolated cluster. Of the new institutions, foreign collaborators seldom stayed beyond five years, while local institutions seldom left after entering the field. Over the 13-year period, local collaboration activity persisted, while local-foreign collaborations were seen to decline. Over time, the network topology became more akin to that of a small-world network. The findings of the study may support innovation management by guiding institutional strategies for effective collaboration

Evaluation of POSSUM and P-POSSUM as predictors of mortality and morbidity in patients undergoing laparotomy at a referral hospital in Nairobi, Kenya

Background The Physiological and Operative Severity Score for enUmeration of Morbidity and Mortality (POSSUM) and its Portsmouth modification (P-POSSUM) were developed for comparative audit in surgical patients. This study evaluated applicability of these systems in estimating mortality and morbidity risks in a cohort of patients undergoing laparotomy at the national referral hospital in Nairobi, Kenya. Methods Data of 166 patients undergoing laparotomy was subjected to POSSUM and P-POSSUM scoring systems and analyzed using linear and exponential methods. The discrimination power of POSSUM and P-POSSUM as predictors of surgical outcome was measured using the receiver–operating characteristic (ROC) curve. Results The overall observed to expected (O:E) ratio using linear analysis was 0.29:1 (POSSUM) and 0.67:1 (P-POSSUM) while exponential analysis gave an O:E of 0.2:1 (POSSUM) and 0.4:1 (P-POSSUM). The predicted morbidity using POSSUM was 1.09:1 (linear analysis) and 1:1 (exponential analysis). Hosmer–Lemeshow analysis did not show a significant lack of fit with the observed mortality when applied to POSSUM and P-POSSUM. The area under ROC curve was 0.74 (POSSUM) and 0.78 (P-POSSUM). Conclusion Our results support the suitability of P-POSSUM and POSSUM scoring systems to stratify morbidity and mortality risk in our study population

Medical device regulation in South Africa: The Medicines and Related Substances Amendment Act 14 of 2015

The Medicines and Related Substances Amendment Act, 14 of 2015, has brought significant changes in the regulation of medical devices in South Africa. The highlights include the establishment of a regulatory authority, the South African Health Products Regulatory Agency, the introduction of a tier-based licensing and registration system, and restriction of bonusing and sampling in the sale of medical devices. The enactment of the new regulations is a positive development for the South African medical device industry. However, the impact of the regulations will depend on implementation. Conditions that will support the success of the regulations include creating a critical mass of skilled personnel and measures that ensure timely registration. South Africa can learn from the experiences and practices of other countries that have introduced medical device regulations in recent years

A Nonlinear Correlation Measure for Intrusion Detection

The popularity of the Internet supplies attackers with a new means to violate any organizations and individuals. This raises the concerns of the Internet users and research community. One of the effective solutions of addressing this issue is Intrusion Detection System (IDS), which is defined as a type of security tools used to detect any malicious behaviors on computer networks. However, IDSs are commonly prone to high false positive rates. In order to solve this technical challenge, this paper proposes an effective Nonlinear Correlation Coefficient (NCC) based measure, which can accurately extract both linear and nonlinear correlations between network traffic records, for intrusion detection. Then, we demonstrate the effectiveness of our proposed NCC-based measure in extracting correlations by comparing against the Pearsonâs Correlation Coefficient (PCC) based measure. The demonstration is conducted on KDD Cup 99 data set, and the experimental results show that our proposed NCC-based measure not only helps reduce false alarm rate, but also helps distinguish normal and abnormal behaviors efficiently

Ambient noise analysis for characterizing sub-surface dynamic parameters

Ambient noise analysis of horizontal to vertical spectral ratio (HVSR) method has been used widely to provide reliable estimates of the site fundamental frequency and to constrain the inversion of near-surface shear wave velocity. The present paper focuses on the site measurement using the aforementioned analysis by means of the HVSR method for characterizing sub-surface dynamic parameters in the City of Banda Aceh, Indonesia. A Guralp CMG-6TD broadband seismometer was used in this study to cover a wide frequency range from 0.033 Hz to 50 Hz in standard operation. The instrument was deployed at two different sites (i.e. Location#1 of Blang Padang and Location#2 of Stadion Dirmutala) in the City of Banda Aceh for at least 2 hours for ambient noise recording. This continuous of 2 hours' microtremor time series was separated into 30 minutes record from which the site fundamental frequency and shear wave velocity of the measured site were deduced. The later sub-surface dynamic parameter was validated using another technique of reflection seismic. This investigation suggests the fundamental frequency of 0.45 Hz at Location#1 and of 0.65 Hz at Location#2. The estimated shear wave velocity of the top 30 m, Vs,30 of this investigation is 165 m/s at Location#1 and 156 m/s at Location#2. Both the site fundamental frequency and shear wave velocity are important for infrastructure design in the high seismic region of Banda Aceh, Indonesia

Ecosystem services bundles:challenges and opportunities for implementation and further research

Background : the concept of ‘ecosystem services bundles’, i.e. ecosystem services that repeatedly appear together across space and/or time, has been developed and refined as part of an integrated approach to assess interactions between ecosystem services. Nevertheless, published evidence of actual use of bundles in decision-making is lacking. In the light of this gap, a review of what bundle approaches have shown and what they can bring to decision-making is timely. Method : we conducted two separate systematic reviews. The first one addressed emerging issues within what we identify as the diverse utilisation and definition of the concept of ‘bundle’ in the literature. The second one focused on papers dealing with bundles as sets of consistently associated services. Review Synthesis : the review first highlights that the confusion surrounding the term ‘bundle’ in ecosystem services literature threatens to weaken the potential for analysis of bundles to inform decision-making. Then, thanks to the review of peer-reviewed papers that detect bundles as sets of consistently associated services, we analyse the diversity of methodological choices and we detail the interactions observed between different ecosystem services across the literature. We also show that landscape features, socio-economic conditions and institutional factors are all potential drivers for the occurrence of specific bundles in a landscape. Discussion : overall, it appears that the analysis of bundles provides an opportunity to enhance policy effectiveness. Nevertheless, the methodological challenges linked to the identification and interpretation of bundles call for careful and reflective study designs. We anticipate that this review will lead to a better understanding by scientists and practitioners of the potential for bundle studies to inform decision-making