133 research outputs found
Liveness-Based Garbage Collection for Lazy Languages
We consider the problem of reducing the memory required to run lazy
first-order functional programs. Our approach is to analyze programs for
liveness of heap-allocated data. The result of the analysis is used to preserve
only live data---a subset of reachable data---during garbage collection. The
result is an increase in the garbage reclaimed and a reduction in the peak
memory requirement of programs. While this technique has already been shown to
yield benefits for eager first-order languages, the lack of a statically
determinable execution order and the presence of closures pose new challenges
for lazy languages. These require changes both in the liveness analysis itself
and in the design of the garbage collector.
To show the effectiveness of our method, we implemented a copying collector
that uses the results of the liveness analysis to preserve live objects, both
evaluated (i.e., in WHNF) and closures. Our experiments confirm that for
programs running with a liveness-based garbage collector, there is a
significant decrease in peak memory requirements. In addition, a sizable
reduction in the number of collections ensures that in spite of using a more
complex garbage collector, the execution times of programs running with
liveness and reachability-based collectors remain comparable
Attaching DNA to Nanoceria: Regulating Oxidase Activity and Fluorescence Quenching
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Applied Materials and Interfaces copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see Pautler, R., Kelly, E. Y., Huang, P.-J. J., Cao, J., Liu, B., & Liu, J. (2013). Attaching DNA to Nanoceria: Regulating Oxidase Activity and Fluorescence Quenching. ACS Applied Materials & Interfaces, 5(15), 6820–6825. https://doi.org/10.1021/am4018863Cerium oxide nanoparticles (nanoceria) have recently emerged as a nanozyme with oxidase activity. In this work, we present a few important interfacial properties of nanoceria. First, the surface charge of nanoceria can be controlled not only by adjusting pH but also by adsorption of simple inorganic anions. Adsorption of phosphate and citrate gives negatively charged surface over a broad pH range. Second, nanoceria adsorbs DNA via the DNA phosphate backbone in a sequence-independent manner; DNA adsorption inhibits its oxidase activity. Other anionic polymers display much weaker inhibition effects. Adsorption of simple inorganic phosphate does not have the inhibition effect. Third, nanoceria is a quencher for many fluorophores. These discoveries provide an important understanding for further use of nanoceria in biosensor development, materials science, and nanotechnology.University of Waterloo ||
Canadian Foundation for Innovation ||
Natural Sciences and Engineering Research Council ||
Ontario Ministry of Research and Innovation |
Immunomodulation by Different Types of N-Oxides in the Hemocytes of the Marine Bivalve Mytilus galloprovincialis
The potential toxicity of engineered nanoparticles (NPs) for humans and the environment represents an emerging issue. Since the aquatic environment represents the ultimate sink for NP deposition, the development of suitable assays is needed to evaluate the potential impact of NPs on aquatic biota. The immune system is a sensitive target for NPs, and conservation of innate immunity represents an useful basis for studying common biological responses to NPs. Suspension-feeding invertebrates, such as bivalves, are particularly at risk to NP exposure, since they have extremely developed systems for uptake of nano and microscale particles integral to intracellular digestion and cellular immunity. Evaluation of the effects of NPs on functional parameters of bivalve immunocytes, the hemocytes, may help understanding the major toxic mechanisms and modes of actions that could be relevant for different NP types in aquatic organisms.In this work, a battery of assays was applied to the hemocytes of the marine bivalve Mytilus galloprovincialis to compare the in vitro effects of different n-oxides (n-TiO2, n-SiO2, n-ZnO, n-CeO2) chosen on the basis of their commercial and environmental relevance. Physico-chemical characterization of both primary particles and NP suspensions in artificial sea water-ASW was performed. Hemocyte lysosomal and mitochondrial parameters, oxyradical and nitric oxide production, phagocytic activity, as well as NP uptake, were evaluated. The results show that different n-oxides rapidly elicited differential responses hemocytes in relation to their chemical properties, concentration, behavior in sea water, and interactions with subcellular compartments. These represent the most extensive data so far available on the effects of NPs in the cells of aquatic organisms. The results indicate that Mytilus hemocytes can be utilized as a suitable model for screening the potential effects of NPs in the cells of aquatic invertebrates, and may provide a basis for future experimental work for designing environmentally safer nanomaterials
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