Packet Arrival Analysis in Wireless Sensor Networks

Distributed sensor networks have been discussed for more than 30 years, but the vision of Wireless Sensor Networks (WSNs) has been brought into reality only by the rapid advancements in the areas of sensor design, information technologies, and wireless networks that have paved the way for the proliferation of WSNs. The unique characteristics of sensor networks introduce new challenges, amongst which prolonging the sensor lifetime is the most important. WSNs have seen a tremendous growth in various application areas including health care, environmental monitoring, security, and military purposes despite prominent performance and availability challenges. Clustering plays an important role in enhancement of the life span and scalability of the network, in such applications. Although researchers continue to address these grand challenges, the type of distributions for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. Modelling the behaviour of the networks becomes essential for estimating the performance metrics and further lead to decisions for improving the network performance, hence highlighting the importance of identifying the type of inter-arrival distributions at the cluster head. In this paper, we present extensive discussions on the assumptions of exponential distributions in WSNs, and present numerical results based on Q-Q plots for estimating the arrival distributions. The work is further extended to understand the impact of end-to-end delay and its effect on inter-arrival time distributions, based on the type of medium access control used in WSNs. Future work is also presented on the grounds that such comparisons based on simple eye checks are insufficient. Since in many cases such plots may lead to incorrect conclusions, demanding the necessity for validating the types of distributions. Statistical analysis is necessary to estimate and validate the empirical distributions of the arrivals in WSNs

Building a Sustainable Comprehensive Multiple Myeloma Program in Western Kenya

Despite improved treatment strategies for multiple myeloma (MM), patient outcomes in low- and middle-income countries remain poor, unlike high-income countries. Scarcity of specialized human resources and diagnostic, treatment, and survivorship infrastructure are some of the barriers that patients with MM, clinicians, and policymakers have to overcome in the former setting. To improve outcomes of patients with MM in Western Kenya, the Academic Model Providing Access to Healthcare (AMPATH) MM Program was set up in 2012. In this article, the program's activities, challenges, and future plans are described distilling important lessons that can be replicated in similar settings. Through the program, training on diagnosis and treatment of MM was offered to healthcare professionals from 35 peripheral health facilities across Western Kenya in 2018 and 2019. Access to antimyeloma drugs including novel agents was secured, and pharmacovigilance systems were developed. Finally, patients were supported to obtain health insurance in addition to receiving peer support through participation in support group meetings. This article provides an implementation blueprint for similar initiatives aimed at increasing access to care for patients with MM in underserved areas

Retrospective Analysis of Presentation, Treatment, and Outcomes of Multiple Myeloma at a Large Public Referral Hospital in Eldoret, Kenya

Purpose: Treatment patterns and survival outcomes of patients with multiple myeloma (MM) in Kenya have not been adequately characterized. The objectives of this study were to describe the clinical, laboratory, and imaging findings at diagnosis, to describe the treatment offered, and to determine the survival outcomes of patients with MM over an 11-year period. Patients and methods: A retrospective chart review was carried out for all patients who were diagnosed and treated for MM at Moi Teaching and Referral Hospital from 2009 to 2019. The Kaplan-Meier method was used to estimate survival. Factors affecting survival were identified using univariate and multivariate analyses. Results: A total of 221 patient charts were analyzed of which 124 belonged to male patients (56.1%). The median age at diagnosis was 61 years. Bone pain was the most common presenting complaint observed in 69.6% of 194 patients assessed. Out of 102 patients who received imaging studies, 60 (58.8%) had lytic lesions, 30 (29.4%) had fractures, whereas 30 (29.4%) had spinal cord compression. Anemia, renal failure, and hypercalcemia were observed in 87/187 (46.5%), 22/161 (13.7%), and 23/42 (54.8%) patients, respectively. Thalidomide and dexamethasone (65.2%); bortezomib, thalidomide, and dexamethasone (14.6%); and melphalan and prednisolone (11.9%) were the most prescribed initial chemotherapy regimens among 219 patients analyzed. Overall survival at 1 and 5 years was 70% and 21%, respectively; median overall survival was 29.0 months. In multivariate analysis, male sex (hazard ratio [HR] 1.9), baseline anemia (HR 1.8), and baseline renal failure (HR 3.2) were associated with significantly shorter survival. Conclusion: Survival outcomes were poor despite increased use of multiagent-based chemotherapy regimens. Greater access to available diagnostics and treatments is required to achieve rational treatment and increased survival

falciparum dihydrofolate reductase and

Trends in drug resistance codons in Plasmodiu

First report of banana bunchy top disease caused by Banana bunchy top virus in Uganda

Banana bunchy top virus (BBTV) that causes banana bunchy top disease (BBTD) is ranked among the top 100 invasive species in the world. Despite being omnipresent in the Democratic Republic of Congo (DR Congo) and South-Western Rwanda for over 2 decades, BBTV had not been reported in neighbouring Uganda. However, in 2020, banana plants with BBTD characteristic symptoms were observed in Arua City located in the North Western part of Uganda, bordering DR Congo. BBTV in these plants was confirmed using PCR and the comparison of the genomic DNA nucleotide sequence with nucleotide sequences in NCBI data base (https://www.ncbi.nlm.nih.gov/). The gDNA nucleotide sequence had 98-99% similarity with BBTV isolates form different countries in Africa, Asia, South Pacific and the USA. These results constitute the first confirmation of BBTD in Uganda. This infection is anticipated to have been introduced from DR Congo, mainly through infected planting materials. Once established, BBTD is very difficult to control on small-scale farms. It is therefore crucial to urgently understand the current spread of the virus, determine its risk to banana production in Uganda and devise proactive measures for its management

An Analytical Model for Bounded WSNs with Unreliable Cluster Heads and Links

In Wireless Sensor Networks (WSNs), performance and availability are important in providing Quality of Service (QoS). WSNs are prone to failures that may result from software and hardware malfunctions, battery drain, tampering and link failures. In addition, sensors are resource constrained in terms of inadequate processing capacity, limited storage memory and restricted power supply. Alternating sensor operations between sleep and active modes whilst saving energy, has also introduced more challenges to the performance and dependability of WSN systems. This paper therefore seeks to investigate performance and availability concerns resulting from link and node failures in addition to the buffer restrictions and challenges caused by alternating sensor operations between active and sleep states. First, a finite queue capacity analytical model integrating performance and availability in the presence of node and channel failures and repairs is developed. Using the model, we analyse performance and availability of WSNs in terms of network throughput, delays and dependability. Finally, the model is used to evaluate tradeoffs between performance metrics. The analytical solutions using Spectral Expansion and Kolmogorov Forward equations as well as the simulation results are in good agreement

T-Cell Responses to COVID-19 Vaccines and Breakthrough Infection in People Living with HIV Receiving Antiretroviral Therapy

People living with HIV (PLWH) can exhibit impaired immune responses to vaccines. Accumulating evidence indicates that PLWH, particularly those receiving antiretroviral therapy, mount strong antibody responses to COVID-19 vaccines, but fewer studies have examined cellular immune responses to the vaccinations. Here, we used an activation-induced marker (AIM) assay to quantify SARS-CoV-2 spike-specific CD4+ and CD8+ T cells generated by two and three doses of COVID-19 vaccines in 50 PLWH receiving antiretroviral therapy, compared to 87 control participants without HIV. In a subset of PLWH, T-cell responses were also assessed after post-vaccine breakthrough infections and/or receipt of a fourth vaccine dose. All participants remained SARS-CoV-2 infection-naive until at least one month after their third vaccine dose. SARS-CoV-2 infection was determined by seroconversion to a Nucleocapsid (N) antigen, which occurred in 21 PLWH and 38 control participants after the third vaccine dose. Multivariable regression analyses were used to investigate the relationships between sociodemographic, health- and vaccine-related variables, vaccine-induced T-cell responses, and breakthrough infection risk. We observed that a third vaccine dose boosted spike-specific CD4+ and CD8+ T-cell frequencies significantly above those measured after the second dose (all p 0.1), but CD8+ T-cell responses were modestly lower in PLWH after the third dose (p = 0.02), an observation that remained significant after adjusting for sociodemographic, health- and vaccine-related variables (p = 0.045). In PLWH who experienced a breakthrough infection, median T-cell frequencies increased even higher than those observed after three vaccine doses (p < 0.03), and CD8+ T-cell responses in this group remained higher even after a fourth vaccine dose (p = 0.03). In multivariable analyses, the only factor associated with an increased breakthrough infection risk was younger age, which is consistent with the rapid increase in SARS-CoV-2 seropositivity that was seen among younger adults in Canada after the initial appearance of the Omicron variant. These results indicate that PLWH receiving antiretroviral therapy mount strong T-cell responses to COVID-19 vaccines that can be enhanced by booster doses or breakthrough infection.Medicine, Faculty ofNon UBCFamily Practice, Department ofMedicine, Department ofPathology and Laboratory Medicine, Department ofReviewedFacultyResearche

Antimalarial Drug Sensitivity Profile of Western Kenya Plasmodium falciparum Field Isolates Determined by a SYBR Green I in vitro Assay and Molecular Analysis

In vitro drug sensitivity and molecular analyses of Plasmodium falciparum track drug resistance. DNA-binding fluorescent dyes like SYBR Green I may allow field laboratories, proximal to P. falciparum collection sites, to conduct drug assays. In 2007–2008, we assayed 121 P. falciparum field isolates from western Kenya for 50% inhibitory concentrations (IC50) against 6 antimalarial drugs using a SYBR Green I in vitro assay: 91 immediate ex vivo (IEV) and 30 culture-adapted, along with P. falciparum reference clones D6 (chloroquine [CQ] sensitive) and W2 (CQ resistant). We also assessed P. falciparum mdr1 (Pfmdr1) copy number and single nucleotide polymorphisms (SNPs) at four codons. The IC50s for IEV and culture-adapted P. falciparum isolates were similar, and approximated historical IC50s. For Pfmdr1, mean copy number was 1, with SNPs common at codons 86 and 184. The SYBR Green I assay adapted well to our field-based laboratory, for both IEV and culture-adapted P. falciparum, warranting continued use