UWSpace

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Recent Submissions

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    Fast Kubernetes Orchestration for Dynamic and Ephemeral Workloads
    (University of Waterloo, 2026-05-28) Abbasi Alaei, Ali
    In recent years, Kubernetes has become the primary choice for orchestrating software deployments on distributed clusters. It abstracts the complexities of the underlying infrastructure, enabling developers to focus on application logic rather than low-level resource management. In addition to traditional long-running services, Kubernetes is increasingly used to manage short-lived and latency-sensitive applications, such as serverless functions that demand fast startup and high deployment churn. The problem with using Kubernetes for these use cases is that it sacrifices performance for high reliability and strong consistency, making it less suitable for performance-critical and dynamically scaled environments. This work identifies etcd, the central storage in Kubernetes, as a critical factor influencing performance due to its persistent and strongly consistent operation. A design change for the Kubernetes control plane is proposed and implemented that employs a complementary metadata store, called Sharded Transient Etcd (STE), alongside the persistent etcd in the Kubernetes cluster. STE stores short-lived entities, such as Pod objects, which are critical yet ephemeral resources, in fast, in-memory storage, while retaining persistent etcd for durability-critical data. This design preserves reliability and failure recovery while significantly improving orchestration performance and scalability. An experimental evaluation shows that the prototype doubles deployment throughput, reduces Pod creation latency by 80%, and improves resource efficiency of Kubernetes components by up to 20% without compromising stability or failure recovery. In addition, the results show that the cold start latency of a widely used Kubernetes-based serverless orchestrator is reduced by more than 60%. While this work is focused on Kubernetes, the resulting insight is applicable to orchestration systems in general.
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    Evolution of the northern rockweed, Fucus distichus, in a Regime of Glacial Cycling: Implications for benthic algal phylogenetics
    (Public Library of Science, 2015-12-02) Laughinghouse IV, Hayword Dail; Muller, Kirsten M.; Adey, Walter H.; Lara, Yannick; Young, Robert; Johnson, Gabriel
    Northern hemisphere rockweeds (Fucus) are thought to have evolved in the North Pacific and then spread to the North Atlantic following the opening of the Bering Strait. They have dispersed and widely speciated in the North Atlantic and its tributary seas. Fucus distichus is likely near the ancestral member of this genus, and studies have shown that there are several species/subspecies in this complex (i.e. F. evanescens and F. gardneri). We used phylogenetic and haplotype analyses to test the phylogenetic relationships and biogeography of F. distichus. Our data and subsequent analyses demonstrate that, unlike previous studies that lacked samples from an extensive geographical area of the Arctic and Subarctic, there is a distinct Arctic haplotype that is the source of subspecies in both the North Pacific and North Atlantic. Fucus distichus occupies a low tide zone habitat, and in Arctic/Subarctic regions it is adapted to the severe stress of sea ice coverage and disturbance during many months per year. We hypothesize that the very large geographic area of Arctic and Subarctic rocky shores available to this species during interglacials, supported by large Arctic/Subarctic fringe areas as well as unglaciated refugia during glacial cycles, provided a robust population and gene pool (described by the Thermogeographic Model). This gene pool dilutes that of the more fragmented and area-limited Temperate/Boreal area populations when they are brought together during glacial cycles. We suggest that similar subspecies complexes for a variety of Arctic/Subarctic shore biota should be examined further in this context, rather than arbitrarily being split up into numerous species.
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    Physical characterization of gemini surfactant-based synthetic vectors for the delivery of linear covalently closed (LCC) DNA ministrings
    (Public Library of Science, 2015-11-12) Sum, Chi Hong; Nafissi, Nafiseh; Slavcev, Roderick A.; Wettig, Shawn
    In combination with novel linear covalently closed (LCC) DNA minivectors, referred to as DNA ministrings, a gemini surfactant-based synthetic vector for gene delivery has been shown to exhibit enhanced delivery and bioavailability while offering a heightened safety profile. Due to topological differences from conventional circular covalently closed (CCC) plasmid DNA vectors, the linear topology of LCC DNA ministrings may present differences with regards to DNA interaction and the physicochemical properties influencing DNA-surfactant interactions in the formulation of lipoplexed particles. In this study, N,N-bis(dimethylhexadecyl)-α,ω-propanediammonium(16-3-16)gemini-based synthetic vectors, incorporating either CCC plasmid or LCC DNA ministrings, were characterized and compared with respect to particle size, zeta potential, DNA encapsulation, DNase sensitivity, and in vitro transgene delivery efficacy. Through comparative analysis, differences between CCC plasmid DNA and LCC DNA ministrings led to variations in the physical properties of the resulting lipoplexes after complexation with 16-3-16 gemini surfactants. Despite the size disparities between the plasmid DNA vectors (CCC) and DNA ministrings (LCC), differences in DNA topology resulted in the generation of lipoplexes of comparable particle sizes. The capacity for ministring (LCC) derived lipoplexes to undergo complete counterion release during lipoplex formation contributed to improved DNA encapsulation, protection from DNase degradation, and in vitro transgene delivery.
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    Prevalence and patterns of tobacco use in Bangladesh from 2009 to 2012: Evidence from International Tobacco Control (ITC) study
    (Public Library of Science, 2015-11-11) Nargis, Nigar; Thompson, Mary E.; Fong, Geoffrey T.; Driezen, Pete; Hussain, A. K. M. Ghulam; Ruthbah, Ummul H.; Quah, Anne C. K.; Abdullah, Abu S.
    Background Smoking and passive smoking are collectively the biggest preventable cause of death in Bangladesh, with major public health burden of morbidity, disability, mortality and community costs. The available studies of tobacco use in Bangladesh, however, do not necessarily employ nationally representative samples needed to monitor the problem at a national scale. This paper examines the prevalence and patterns of tobacco use among adults in Bangladesh and the changes over time using large nationally representative comparable surveys. Methods Using data from two enumerations of the International Tobacco Control (ITC) Bangladesh Project conducted in 2009 and 2012, prevalence estimates are obtained for all tobacco products by socio-economic determinants and sample types of over 90,000 individuals drawn from over 30,000 households. Household level sample weights are used to obtain nationally representative prevalence estimates and standard errors. Statistical tests of difference in the estimates between two time periods are based on a logistic regression model that accounts for the complex sampling design. Using a multinomial logit model, the time trend in tobacco use status is identified to capture the effects of macro level determinants including changes in tobacco control policies. Results Between 2009 and 2012, overall tobacco use went down from 42.4% to 36.3%. The decline is more pronounced with respect to smokeless tobacco use than smoking. The prevalence of exclusive cigarette smoking went up from 7.2% to 10.6%; exclusive bidi smoking remained stable at around 2%; while smoking both cigarette and bidi went down from 4.6% to 1.8%; exclusive smokeless tobacco use went down from 20.2% to 16.9%; and both smokeless tobacco use and smoking went down from 8.4% to 5.1%. In general, the prevalence of tobacco use is higher among men, increases from younger to older age groups, and is higher among poorer people. Smoking prevalence is the highest among the slum population, followed by the tribal population, the national population and the border area population, suggesting greater burden of tobacco use among the disadvantaged groups. Conclusions The overall decline in tobacco use can be viewed as a structural shift in the tobacco market in Bangladesh from low value products such as bidi and smokeless tobacco to high value cigarettes, which is expected with the growth in income and purchasing power of the general population. Despite the reduction in overall tobacco use, the male smoking prevalence in Bangladesh is still high at 37%. The world average of daily smoking among men is 31.15. The Tobacco Control Act 2005 and the Amendment have yet to make a significant impact in curbing tobacco usage in Bangladesh. The findings in this paper further suggest that the tobacco control policies in Bangladesh need to include targeted interventions to restrain the use of particular types of tobacco products among specific demographic and socio-economic groups of the population, such as smoked tobacco among men, smokeless tobacco among women, and both smoked and smokeless tobacco among those living in rural areas, those in low socio-economic status and those belonging to the tribal and the slum population.
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    Modeling invasion dynamics with spatial random-fitness due to micro-environment
    (Public Library of Science, 2015-10-28) Manem, V. S. K.; Kaveh, K.; Kohandel, M.; Sivaloganathan, S.
    Numerous experimental studies have demonstrated that the microenvironment is a key regulator influencing the proliferative and migrative potentials of species. Spatial and temporal disturbances lead to adverse and hazardous microenvironments for cellular systems that is reflected in the phenotypic heterogeneity within the system. In this paper, we study the effect of microenvironment on the invasive capability of species, or mutants, on structured grids (in particular, square lattices) under the influence of site-dependent random proliferation in addition to a migration potential. We discuss both continuous and discrete fitness distributions. Our results suggest that the invasion probability is negatively correlated with the variance of fitness distribution of mutants (for both advantageous and neutral mutants) in the absence of migration of both types of cells. A similar behaviour is observed even in the presence of a random fitness distribution of host cells in the system with neutral fitness rate. In the case of a bimodal distribution, we observe zero invasion probability until the system reaches a (specific) proportion of advantageous phenotypes. Also, we find that the migrative potential amplifies the invasion probability as the variance of fitness of mutants increases in the system, which is the exact opposite in the absence of migration. Our computational framework captures the harsh microenvironmental conditions through quenched random fitness distributions and migration of cells, and our analysis shows that they play an important role in the invasion dynamics of several biological systems such as bacterial micro-habitats, epithelial dysplasia, and metastasis. We believe that our results may lead to more experimental studies, which can in turn provide further insights into the role and impact of heterogeneous environments on invasion dynamics.