Using redundancy to cope with failures in a delay tolerant network

We consider the problem of routing in a delay tolerant net-work (DTN) in the presence of path failures. Previous work on DTN routing has focused on using precisely known network dy-namics, which does not account for message losses due to link failures, buffer overruns, path selection errors, unscheduled de-lays, or other problems. We show how to split, replicate, and erasure code message fragments over multiple delivery paths to optimize the probability of successful message delivery. We provide a formulation of this problem and solve it for two cases: a 0/1 (Bernoulli) path delivery model where messages are ei-ther fully lost or delivered, and a Gaussian path delivery model where only a fraction of a message may be delivered. Ideas from the modern portfolio theory literature are borrowed to solve the underlying optimization problem. Our approach is directly relevant to solving similar problems that arise in replica place-ment in distributed file systems and virtual node placement in DHTs. In three different simulated DTN scenarios covering a wide range of applications, we show the effectiveness of our ap-proach in handling failures

Relationship between health-related quality of life and respiratory health status among coal-based sponge iron plant workers in Barjora, India

Background: Many coal-based sponge iron plant workers have poor health-related quality of life in general, and specifically a poor respiratory health status. However, the relationship between their health-related quality of life and respiratory health status is unknown. Aim: This study investigated the relationship between health related quality of life, measured using the EuroQol- 5D (EQ5D), and respiratory health status, measured using the St. George’s Respiratory Questionnaire (SGRQ), among coal-based sponge iron plant workers in Barjora, India. Method: A cross-sectional study was conducted among coalbased sponge iron plant workers in Barjora, and complete data were available on 252 participants. Spearman’s rank correlation coefficients were reported to show the strength of relationship between health-related quality of life and respiratory health status. Results and conclusion: Significant correlations were found between all EQ5D dimensions/visual analogue scale (VAS) and all SGRQ scores except between EQ5D-VAS and SGRQ-activity. A range of correlations was found. They were moderate between EQ5D-anxiety/depression and SGRQ-symptom, EQ5D-VAS and SGRQ-symptom, and EQ5D-anxiety/depression and SGRQ-total, but weak between all the other factors

Simplifying fault diagnosis in locally managed rural WiFi networks

The last three years have seen a lot of work in making WiFi-enabled Long Distance (WiLD) networking a reality in rural areas. Generally these networks are managed by non-local users who cannot guarantee long term support beyond a pi-lot. For long term operational sustainability, it is essential that maintenance duties be transferred to local administra-tors. In this paper, we argue that the research agenda should expand into areas of simplified diagnosis solutions as an en-abler for locally managed WiLD networks. Motivated by real faults we have seen in our own deployment at the Aravind Eye Hospital, we propose a framework to simplify diagnosis and show some initial results towards this direction. Categories and Subject Descriptor

Hardware speech recognition for user interfaces in low cost, low power devices

We propose a system architecture for real-time hardware speech recognition on low-cost, power-constrained devices. The system is intended to support real-time speech-based user interfaces as part of an effort to bring Information and Communication Technologies (ICTs) to underdeveloped regions of the world. Our system architecture exploits a shared infrastructure model. The computationally intensive task of speech model training and retraining is performed offline by shared servers, while the actual recognition of speech is conducted on low-cost hand-held devices using custom hardware. The recognizer is extremely flexible and can support multiple languages or dialects with speaker-independent recognition.Dynamic loading of speech models is used for changing language grammar and retraining, while reprogramming is used to support evolution of recognition algorithms. The focus on small sets of words (at one time) reduces the complexity, cost and power consumption. We design the speech decoder, the central component of the recognizer, and we validate it via a prototype FPGA implementation. We then use ASIC synthesis to estimate power and size for the design. Our evaluations demonstrate an order of magnitude improvement in power compared with optimized recognition software running on a low-power embedded general-purpose processor of the same technology and of similar capabilities. The synthesis also estimates the area of the design to be about 2.5mm 2, showing potential for lower cost. In designing and testing our recognizer we use datasets in both English and Tamil languages

WiLDNet: Design and Implementation of High Performance WiFi Based Long Distance Networks

WiFi-based Long Distance (WiLD) networks with links as long as 50–100 km have the potential to provide connectivity at substantially lower costs than traditional approaches. However, real-world deployments of such networks yield very poor end-to-end performance due to two reasons. First, the current 802.11 MAC protocol has fundamental shortcomings when used over long-distances. Second, WiLD networks can exhibit high and variable loss characteristics, thereby severely limiting end-to-end throughput. This paper describes the design, implementation and evaluation of WiLDNet, a system that overcomes these two problems and provides enhanced end-to-end performance in WiLD networks. To address the protocol shortcomings, WiLDNet makes several essential changes to the 802.11 MAC protocol, but continues to rely on standard WiFi network cards. To better handle losses and improve link utilization, WiLDNet uses an adaptive lossrecovery mechanism using FEC and bulk acknowledgements. Based on a real-world deployment, WiLDNet provides a 2–5 fold improvement in TCP/UDP throughput (along with significantly reduced loss-rates) in comparison to the best throughput achievable by conventional 802.11 MAC. WiLDNet can also be configured to adapt to a range of end-to-end performance requirements (bandwidth, delay, loss, jitter).

Blunt traumatic dissection of right coronary artery presenting with acute inferior wall myocardial infarction: Dilemma in management

Thirty-nine year male had a history of road traffic accident with polytrauma. At emergency room he started having chest pain with ventricular tachycardia. He was subsequentially diagnosed with right coronary artery dissection secondary to blunt trauma which is an extremely rare cause of inferior wall myocardial infarction. After some dilemmas, he was ultimately treated with intravascular ultrasound guided coronary angioplasty with stenting and had an uneventful recovery