Increased specialization within the forestry industry has led to the rise of a distinct industry known as forestry services. Whereas logging historically encompassed this work, a separate population increasingly participates in the remote grooming and tree planting of forest lands. Physically demanding, dangerously hazardous, and low paying, forestry services work in the Pacific Northwest predominantly employs Mexican and Central American immigrants. As an extension of my honors project at the UW School of Nursing, I examined how occupational injury among this group of workers with correlates with attitudes that workers and employers hold about their work environments. Performing a secondary analysis using survey interview data collected by the UW Pacific Northwest Agricultural Safety & Health Center, and the Northwest Forest Worker Center, I identified top risk perceptions and barriers to workplace safety as reported by workers, as well as by a set of employers and supervisors. Not only was there variation in the prevalence of worker injury between different employers, there was also variation in the perceived attitudes about workplace safety. In future research, it will be possible to link the experiences of workers with the attitudes and policies of those who employ them.

APOBEC3G (A3G) is a host protein that acts as a cytidine deaminase to inhibit HIV replication as part of the innate immune system. A3G has been shown to cause Guanine to Adenosine hypermutation. This host protein cannot deaminate the proviral HIV DNA because of the HIV accessory protein Vif. The Vif protein interrupts the antiviral activity of A3G by inducing ubiquitination and degradation via the host proteasome. In this project, we investigated the deamination ability of A3G and deamination inhibition ability of Vif in vivo. While much of the published work on A3G has involved the investigation of Vif-induced A3G degradation, bacterial models have also revealed a degradation-independent mechanism of A3G inactivation by Vif. We looked for direct inhibition of A3G deamination ability by Vif in vivo. We found that the deamination of the proviral genome was correlated with the concentration of A3G in both NL4-3 and NL4-3 (vif-) strains. Unexpectedly, we observed deamination in the viral genome, in NL4-3 at higher concentration. In comparison, packaging of A3G into NL4-3(vif-) virions caused much larger amount of deamination than in Vif-expressing NL4-3 virions. In the case of wild-type NL4-3, the virus remained infectious despite significant levels of deamination. This represents a novel phenomenon that suggests that the Vif protein has an additional function within the viral replication cycle. Our results, although preliminary, set the stage for a more extensive analysis that may provide novel insights into the biological function of Vif. By studying A3G and Vif interactions in vivo, we are getting closer to understanding the viral replication cycle as it occurs in the human body. By understanding the complete range of function of Vif, new antiviral therapies could be developed to target Vif.

The electrochemical growth of single-crystalline germanium (Ge) nanowires has been previously demonstrated in an aqueous solution for use in complementary metal oxide semiconductor (CMOS) technologies. The motivation for growing these nanowires using electrodeposition is to improve the purity of germanium nanowires relative to traditional synthetic methods. However, nanomaterial growth has been shown to be highly sensitive to both oxygen and water and can lead to impurities, surface layers or morphology changes. . We have grown germanium nanowires in anhydrous organic solution in a nitrogen blanketed electrochemical cell. We have then compared the morphology and material properties of the wires grown in aqueous solution to the wires grown in organic solution to determine the effects of water and oxygen on the wire growth. Improving nanomaterial growth will help in having more efficient computers and cell phones by improving semiconductors.

Palms are a keystone species in tropical rainforests and are thought of as a model species due to their abundance and taxonomic diversity. Because over 90% of palm species diversity is concentrated in the tropical and subtropical biomes today, palm fossils are traditionally interpreted as indicators of warm and wet climate. However, recent work suggests that, in the past, palms may have played an important role also in other biomes. Palms produce great amounts of phytoliths (hardened silica bodies precipitated in and around plant cells), which, after the plant dies, are incorporated into the soil or sediment and preserved as fossils. Importantly, phytoliths are found in many environments where leaf impressions and other macrofossil are typically absent. Palm phytoliths are therefore a valuable potential source of information to reconstruct phylogenetic relationships and interpret the ecology of fossil palms and, by inference, paleoenvironments.Unfortunately, very little work has been done to comprehensively assess how much information about palm taxonomy and ecology can be inferred by palm phytolith morphology. To remedy this, we are conducting a morphometric study of palm phytoliths across the palm phylogenetic tree. We collected leaf samples from 80 palm taxa from herbaria and botanical gardens, then extracted phytoliths using strong oxidants and acids to decompose organic materials. Through measurement of their overall shape and size, as well as the density, size, and shape of phytolith ornamentation we hope to improve overall taxonomic resolution of the palm fossil record. In addition, for each of the taxa we recorded several habitat, climate, and ecology variables to test for biogeographical and ecological signal in palm phytolith morphology.

Climate change is an issue that affects every region of the world, but it has a disproportionate impact on coastal communities and developing countries. Fitting both of these criteria, Costa Rica is extremely vulnerable to the impacts of climate change. Currently, Costa Ricans are known for living “pura vida”, or the pure life, and the country consistently ranks #1 on the Happy Planet Index, a global index of sustainable wellbeing. The main goal of my study was to assess how closely a relationship with the environment impacts one’s perception of success. As an intern for Frontier Programs in Costa Rica, I engaged in conservation research in the Osa Peninsula, subsequently interviewing twenty locals to attempt to answer how environmental relationships and definitions of success are intertwined. Frontier Programs’ goal is to seek out conservation hotspots and work with locals to empower them in future conservation action. My results support the argument that a connection to the environment affects factors people use to define success: happiness, health, and job security. Costa Rica is already feeling the effects of climate change and a loss of biodiversity, and further degradation of this unique natural area has the potential to lead to a decreased connection to nature. This creates a compelling argument for enhancing the climate resiliency of Costa Rica. Closer to home, my work could be extended to make the case that Americans can increase their overall perceptions of success by developing closer relationships with the natural world. 

Pooideae is the largest grass subfamily, comprising over one third of all grass species. Pooid grasses are dominant in C3 grasslands which were once more widespread, but today are restricted to temperate or high elevation areas. During the last 8 million years, many C3 Pooideae were replaced by C4 grasses as regional climates became hotter and drier at low- to mid latitudes, or by forests when local conditions became wetter. Understanding when and where C3 grasslands first formed and when they were replaced by tropical C4 grasslands or forests is important for reconstructing global ecosystems and tracking climate change through time. Since grass macrofossils are rare, microfossils, particularly phytoliths (solid silica particles formed in plant tissue), which can persist in soils for millions of years, are the best paleontological evidence for the presence and abundance of different grasses through time. Grass phytoliths form highly regular shapes which may be specific to clades at low taxonomic levels; however, phytolith shape variation in Pooideae has not been analysed using quantitative methods. To better understand differences in shape within the subfamily, we extracted phytoliths from 36 representative Pooideae species. The phytoliths were imaged using confocal microscopy, and processed into 3D surface meshes for geometric morphometric analysis. We used the meshes as a reference collection to compare similarly processed fossil phytoliths from paleontological sites. Our goal was to use quantitative methods to confirm that the fossil phytoliths were correctly assigned to Pooideae and then to classify the phytoliths to lower taxonomic levels when possible. We used these results to infer a new time sequence for Pooideae evolution. In the future, this reference collection could be used to study domestication and spread of agriculturally important species in the subfamily (e.g., wheat, rye and oats).

Keeping exotic pets carries considerable risk for both the animals and their owners. Unlike with domesticated pets, acessibility to appropriate veterinary services and adequate care information for exotic animals are often minimal and difficult to obtain. Exotic animal laws vary considerably state-by-state, and even county-by-county; leaving generous loopholes for irresponsible and impulsive animal ownership. In this literature review, I've surveyed the physical and psychological impact that captivity has on exotic pets, as well as the health and safety risks posed on humans by the prevalence of zoonotic disease. I have also investigated the plausible options for decreasing the popularity of exotic pet ownership. High mortality rates, inadequate nutrition and living enclosures, and poor socialization have demostrated that exotic animals are at significant risk of not receiving the care they require. Literature on various exotic animals laws from across the United States show that enforceable, well-communicated laws, as well as easily accessible information on exotic animals concerning their associated diseases can be effective in discouraging people from owning exotic animals. Cohesive interstate laws are needed for easier enforcement, and legally requiring pets wholesalers to explicitly publicize the health and safety risks of owning exotic animals would go a long way in decreasing the popularity of owning exotic pets. 

Chalcopyrite copper iron sulfide (CuFeS2) nanocrystals have gained recent interest due to their metal-like optical response, despite their complete lack of free charge carriers. These novel optical characteristics make CuFeS2 an intriguing material for a variety of applications, including photovoltaics and photothermal applications. Unfortunately, synthesis of high quality CuFeS2 nanoparticles is difficult due to the difference in the reactivity of the two cations, often resulting in binary or polydisperse nanocrystals. To gain better control over nanocrystal morphology, we synthesized CuFeS2 nanocrystals via a hot injection method and studied the effect of the cation precursor ratio on the resulting properties of the nanocrystals. Transmission electron microscopy, X-ray diffraction, and UV-vis-NIR spectroscopy were used to analyze the nanocrystal composition, morphology, and optical characteristics. Based on the characterization data, a 1:2 molar ratio of copper to iron precursor was optimal for producing high quality, monodisperse CuFeS2 nanocrystals. These developments in morphological control will aid in future studies of quasi-static resonances in these materials.

Increased levels of atmospheric carbon dioxide (CO2) reduce the nutritional content of rice grains, particularly iron (Fe) and zinc (Zn). Rice serves as a staple food crop for more than two billion people across the world; substantial portions of these rice-dependent populations also suffer from iron and zinc deficiencies. In rice, the effect of increased CO2 on Fe and Zn differs between cultivars. With better mechanistic understanding as to why, informed plant breeding and cultivar selection is a likely path towards ameliorating this problem. Little is known about the mechanisms behind CO2-induced reduction of grain nutrition. Increased CO2 changes the pH of rice paddy soil, facilitating the release of cations (including Fe and Zn), which leads to increased uptake to above ground plant tissues. However, this does not result in increased concentrations of these compounds in the rice grain. Several explanations have been advanced for this paradox, but most work on the topic has relied on free-air carbon enrichment (FACE) installations, which cannot control many potentially important variables. In particular, reduced transpiration under elevated CO2 may obscure differences between CO2-induced carbohydrates. Additionally, the fine-scale impacts of elevated CO2 on the rice rhizosphere have been poorly studied. Our study is attempting to close these knowledge gaps: we have grown rice plants under elevated and current CO2 conditions, while maintaining even transpiration between treatments via controlled relative humidity. We have paired these experimental manipulations with oxygen optode-based visualizations of the undisturbed rice rhizosphere, which has directed accurate soil sampling of rhizosphere and bulk soil porewater samples for analysis of pH, redox, total organic carbon (TOC), and quantification of Fe, As, Ca, Mg, and Zn. Our study seeks to better understand the mechanistic role of increased CO2 on the rice rhizosphere, and its downstream effect on rice grain nutrient quality.

Nanowires have shown significant promise as high-capacity, conversion-type lithium-ion battery negative electrodes. Investigating the local properties of these materials during cycling has primarily been done via in-situ transmission electron microscopy or synchrotron-based techniques. Both techniques require highly specialized equipment that is not readily available. Atomic force microscope (AFM)-based measurements of electronic and ionic transport offer another alternative. However, analyzing these electrode materials via AFM has proven difficult due to the large surface variations in Z-height and the flexibility of the wires, which can trap and damage AFM tips. Therefore, sample preparation becomes critical. In this study we screened a variety of preparation methods including epoxies and resins and from those results, determined successful methods to prepare and ultramicrotome samples to create thin slices of electrode that can support analysis via AFM. These images allow for the elucidation of surface characteristics to support future surface functionalization and show that AFM can be applied to the imaging of these types of electrode materials to obtain nanoscale properties. A stronger understanding of local properties in these materials is critical to future developments that are highly anisotropic and require nanostructures.

Phytoliths are microscopic silica bodies that form in many plants. Being resistant to organic decomposition, they can be used to track plant evolution and past vegetation changes. Although they were traditionally considered as non-functional cellular by-products, recent studies suggest that phytoliths may have photonic, structural, nutritional and defensive benefits in plant growth and survival. Grasses, which are large terrestrial producers of biogenic silica, are the suitable model system for studying the adaptive significance of silica accumulation in plants. Identification of phytoliths within the plants (for studying function) and inside the sediments (for studying evolution of vegetation) have so far been limited to optical microscopy-based methods where fluorescent dyes are commonly used to increase contrast between silica bodies and plant tissue. Due to their non-specific nature, however, fluorescent dyes often accumulate in different parts of the cells and silicified tissues, causing false positives and leading to incomplete staining and difficulties to construct 3D structures. With exquisite molecular recognition and assembly properties, solid-binding peptide tags (dubbed GEPIs) are surface functionalization moieties that can be chimerized with fluorescent and utilized as material-specific probes to selectively label variety of inorganic materials at surfaces and within interfaces. Our goal is to develop peptide-based phytolith-specific fluorescent probes to identify and delineate phytolith shapes with high precision and in situ. Using phytoliths-specific peptides probes, designed and chimerized with fluorescent molecules, our goal is to incubate different grass species, and visualize them using laser-confocal microscopy. We hypothesize that the novel molecular construct enable specific detection of phytoliths in situ. The method we are developing will offer a unique solution for fast and accurate identification and 3D organization of inorganic nano- and micro-structures in tissues from living plants and in paleontological samples.