RESUMO
Prioritizing the heterogeneous traffic for Wireless Sensor Networks (WSNs) imposes an important performance challenge for Internet of Things (IoT) applications. Most past preemptive MAC schemes are based on scheduling the high priority packets earlier than those of lower priority. However, in a majority of these schemes, high priority traffic must wait for the ongoing transmission of lower priority traffic due to the non-availability of an interruption mechanism. This paper presents the design and high-level implementation details of a fragmentation scheme (FROG-MAC) for heterogeneous traffic in WSN. FROG-MAC aims at guaranteeing quick transmission of high priority/emergency traffic by interrupting ongoing on channel transmissions. High level implementation of FROG-MAC has been developed in MATLAB as a proof of concept. Traffic of two priorities was generated and a single hop star topology of 100 nodes was used for the experiments. Effect of the proposed fragmentation scheme has been evaluated on delay and Packet Drop Ratio (PDR) for both traffic types, by varying the packet size and fragment size. Simulation results have suggested that with the increasing packet size, the delay and PDR increase for both traffic types. When fragmentation was applied, the performance of high priority traffic significantly improved as compared to the low priority for both the parameters, delay and PDR. Furthermore, it has been found that decreasing the fragment size for low priority traffic results in reducing the delay for high priority traffic.
RESUMO
OBJECTIVE: To determine Sustained Viral Response (SVR) to Interferon (IFN) and ribavirin therapy in chronic hepatitis C patients of genotype 2 and 3. STUDY DESIGN: Case series. PLACE AND DURATION OF STUDY: The Garden Clinic, Lahore, from June 1997 to August 2007. METHODOLOGY: All patients of both genotypes 2 and 3 receiving combination therapy were included. Standard IFN with ribavirin was started in 648 (90%) patients of genotype 2 and 3, whereas 73 (10%), all genotype 3 received pegylated IFN. Outcome parameters including End of Treatment Response (ETR) [negative PCR at the end of therapy], sustained viral response (SVR) [negative PCR both at the end of treatment and 6 months later] and relapse (PCR negative at the end of treatment but positive 6 months later) were determined. Data were analyzed using student's t-test and Chi-square. RESULTS: A total of 721 patients of genotype 2 and 3 were evaluated with male to female ratio of 1.78:1 and mean age 39.8 +/- 9.17 years. Twenty six (3.6%) patients were of genotype 2, while 695 (96.4%) had genotype 3. Six hundred and ten patients (84.6%) completed therapy, as per protocol, whereas 58 (8.04%) had therapy beyond 6 months. SVR was 72.7% with better outcome in genotype 2 (80%) than in 3 (72%) and in those on pegylated IFN and ribavirin (85%) than patients on standard IFN-based therapy (71.1%). Relapse was seen in 116 (16.1%) and 80 (11.1%) were non-responders. Patients with baseline ALT 2-4 x UNL had better SVR than patients with ALT < 2x UNL (p-value 0.01). CONCLUSION: Genotype 3 was the predominant type of virus in the studied patients. SVR patients was 72.7%. Outcome was better with high baseline ALT and pegylated interferon combination therapy.
