Mitigating the Impact of Faults in Unreliable Memories for Error-Resilient Applications

Inherently error-resilient applications in areas such as signal processing, machine learning and data analytics provide opportunities for relaxing reliability requirements, and thereby reducing the overhead incurred by conventional error correction schemes. In this paper, we exploit the tolerable imprecision of such applications by designing an energy-efficient fault-mitigation scheme for unreliable data memories to meet target yield. The proposed approach uses a bit-shuffling mechanism to isolate faults into bit locations with lower significance. This skews the bit-error distribution towards the low order bits, substantially limiting the output error magnitude. By controlling the granularity of the shuffling, the proposed technique enables trading-off quality for power, area, and timing overhead. Compared to error-correction codes, this can reduce the overhead by as much as 83% in read power, 77% in read access time, and 89% in area, when applied to various data mining applications in 28nm process technology.

Design and deployment of secure, robust, and resilient SDN Controllers

The scale of the Software-Defined Network (SDN) Controller design problem has become apparent with the expansion of SDN deployments. Initial SDN deployments were small-scale, single controller environments for research and usecase testing. Today, enterprise deployments requiring multiple controllers are gathering momentum e.g. Google’s backbone network, Microsoft’s public cloud, and NTT’s edge gateway. Third-party applications are also becoming available e.g. HP SDN App Store. The increase in components and interfaces for the evolved SDN implementation increases the security challenges of the SDN controller design. In this work, the requirements of a secure, robust, and resilient SDN controller are identified, stateof-the-art open-source SDN controllers are analyzed with respect to the security of their design, and recommendations for security improvements are provided. This contribution highlights the gap between the potential security solutions for SDN controllers and the actual security level of current controller designs.

Strategies to improve the accuracy of vision measurement by teachers in rural Chinese secondary schoolchildren: Xichang Pediatric Refractive Error Study (X-PRES) report no. 6.

OBJECTIVE: To assess and improve the accuracy of lay screeners compared with vision professionals in detecting visual impairment in secondary schoolchildren in rural China. METHODS: After brief training, 32 teachers and a team of vision professionals independently measured vision in 1892 children in Xichang. The children also underwent vision measurement by health technicians in a concurrent government screening program. RESULTS: Of 32 teachers, 28 (87.5%) believed that teacher screening was worthwhile. Sensitivity (93.5%) and specificity (91.2%) of teachers detecting uncorrected presenting visual acuity of 20/40 or less were better than for presenting visual acuity (sensitivity, 85.2%; specificity, 84.8%). Failure of teachers to identify children owning but not wearing glasses and teacher bias toward better vision in children wearing glasses explain the worse results for initial vision. Wearing glasses was the student factor most strongly predictive of inaccurate teacher screening (P < .001). The sensitivity and specificity of the government screening program detecting low presenting visual acuity were 86.7% and 28.7%, respectively. CONCLUSIONS: Teacher vision screening after brief training can achieve accurate results in this setting, and there is support among teachers for screening. Screening of uncorrected rather than presenting visual acuity is recommended in settings with a high prevalence of corrected and uncorrected refractive error. Low specificity in the government program renders it ineffective.

Attitudes of students, parents, and teachers toward glasses use in rural China.

OBJECTIVE:

To use focus groups to understand barriers to glasses use among children in rural China.

METHODS:

Separate focus groups were conducted between December 17, 2007, and August 5, 2008, for the following 3 groups at each of 3 schools in rural China: children aged 14 to 18 years with myopia of less than -0.5 diopters in both eyes, those children's parents, and those children's teachers. Participants were also asked to rank their responses to questions about glasses use. The focus group transcripts were coded independently by 2 investigators using qualitative data management software.

RESULTS:

Respondents of all 3 types indicated that glasses purchase and wear should be delayed in children with early myopia and might be harmful to the eyes. Parents and students reported being uncertain about children's actual myopia status and whether glasses should be worn. Parents ranked their most common reason for not buying glasses as being "too busy with work," whereas "too expensive" ranked low. Inconvenience was ranked as an important reason for not wearing glasses among all 3 student groups. "Accuracy of lens power" was the first-ranked requirement for glasses among all student groups, whereas "new and attractive styles" was ranked last by all. All 3 types of respondents believed that wearing glasses or failing to wear them might worsen myopia.

CONCLUSIONS:

Educational programs are needed to address significant knowledge gaps in families and schools about glasses use in rural China. Cost and the need for attractive styles may not be significant barriers to use in this setting, raising the possibility of paying for such programs through cost recovery.

Heterogeneous error-resilient scheme for spectral analysis in ultra-low power wearable electrocardiogram devices

Wearable devices performing advanced bio-signal analysis algorithms are aimed to foster a revolution in healthcare provision of chronic cardiac diseases. In this context, energy efficiency is of paramount importance, as long-term monitoring must be ensured while relying on a tiny power source. Operating at a scaled supply voltage, just above the threshold voltage, effectively helps in saving substantial energy, but it makes circuits, and especially memories, more prone to errors, threatening the correct execution of algorithms. The use of error detection and correction codes may help to protect the entire memory content, however it incurs in large area and energy overheads which may not be compatible with the tight energy budgets of wearable systems. To cope with this challenge, in this paper we propose to limit the overhead of traditional schemes by selectively detecting and correcting errors only in data highly impacting the end-to-end quality of service of ultra-low power wearable electrocardiogram (ECG) devices. This partition adopts the protection of either significant words or significant bits of each data element, according to the application characteristics (statistical properties of the data in the application buffers), and its impact in determining the output. The proposed heterogeneous error protection scheme in real ECG signals allows substantial energy savings (11% in wearable devices) compared to state-of-the-art approaches, like ECC, in which the whole memory is protected against errors. At the same time, it also results in negligible output quality degradation in the evaluated power spectrum analysis application of ECG signals.

Applied behaviour analysis: What do teachers of students with autism spectrum disorder know

With rising numbers of school-aged children with autism educated in mainstream classrooms and applied behaviour analysis (ABA) considered the basis of best practice, teachers’ knowledge in this field has become a key concern for inclusion. Self-reported knowledge of ABA of special needs teachers (n=165) was measured and compared to their actual knowledge of ABA demonstrated in accurate responses to a multiple-choice test. Findings reported here show that teachers’ self-perceived knowledge exceeded actual knowledge and that actual knowledge of ABA was not related to training received by government agency. Implications for teacher training are discussed.

How do clinicians become teachers? A communities of practice perspective.

There is widespread acceptance that clinical educators should be trained to teach, but faculty development for clinicians is undermined by poor attendance and inadequate learning transfer. As a result there has been growing interest in situating teacher development initiatives in clinical workplaces. The relationship between becoming a teacher and clinical workplace contexts is under theorised. In response, this qualitative research set out to explore how clinicians become teachers in relation to clinical communities and institutions. Using communities of practice (CoP) as a conceptual framework this research employed the sensitising concepts of regimes of competence and vertical (managerial) and horizontal (professional) planes of accountability to elucidate structural influences on teacher development. Fourteen hospital physicians completed developmental timelines and underwent semi-structured interviews, exploring their development as teachers. Despite having very different developmental pathways, participants’ descriptions of their teacher identities and practice that were remarkably congruent. Two types of CoP occupied the horizontal plane of accountability i.e. clinical teams (Firms) and communities of junior doctors (Fraternities). Participants reproduced teacher identities and practice that were congruent with CoPs’ regimes of competence in order to gain recognition and legitimacy. Participants also constructed their teacher identities in relation to institutions in the vertical plane of accountability (i.e. hospitals and medical schools). Institutions that valued teaching supported the development of teacher identities along institutionally defined lines. Where teaching was less valued, clinicians adapted their teacher identities and practices to suit institutional norms. Becoming a clinical educator entails continually negotiating one’s identity and practice between two potentially conflicting planes of accountability. Clinical CoPs are largely conservative and reproductive of teaching practice whereas accountability to institutions is potentially disruptive of teacher identity and practice.