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Understanding the health perceptions and protective behavioral factors for cannabis edibles in an online community of cannabis users
No full textFrequent cannabis use has been associated with various adverse outcomes, including cannabis use disorder, cognitive decline, psychotic symptoms, and pulmonary issues. Despite these potential harms, daily use of cannabis has been on the rise in young adults and middle-aged adults. While smoking cannabis flower remains the most common method of consumption, alternative forms such as edibles have grown in popularity. Edibles are particularly interesting due to a paradox in users’ health perceptions: edibles are seen as both having the potential to cause harm and as a harm reduction strategy. Many users describe edibles as unpredictable because of difficulties estimating the onset and intensity of their effects, leading to overconsumption and negative experiences like anxiety. At the same time, edibles are often viewed by users as a harm reduction method, mainly because they avoid the lung damage associated with smoking. These perceptions suggest that edibles are riskier or safer than other alternatives, depending on the context and goal of use. This dissertation will examine the subreddit r/trees to explore the conversations about edible use, health perceptions of edible use, and how people protect themselves against the possible negative consequences of edible use. The aims of this dissertation are the following: (1) to explore the discourse around edibles in an online community of cannabis users, (2) to explore the health perceptions of edibles by analyzing an online community of cannabis users, and (3) to explore the strategies that edible users practice minimizing adverse health consequences.
In the first paper, Latent Dirichlet Allocation (LDA), a topic modeling technique, was applied to general discussions in r/trees. Thirty-five topics were identified, including Smoking paraphernalia, Connecting with the community, and Legal status of cannabis. Edibles appeared in two topics: (1) Dosing for edibles and smoking, where users discussed THC/CBD doses and sought dosage advice, and (2) Transforming cannabis, which focused on creating edibles and other cannabis-derived products. These findings show that edibles are a consistent part of broader cannabis conversations, discussed both as a consumption method and as a form of preparation. Topic frequency trends were further analyzed using moving averages.
In the second paper, LDA was applied to posts specifically mentioning edibles or edible products to examine health perceptions and protective behavioral strategies (PBS). Fifteen topics were identified, such as Questions about edibles, Cannabis methods of consumption, and Inviting friends to use cannabis. Health perceptions emerged in three topics: Anxiety after using cannabis, Cannabis methods of consumption, and Medical cannabis use. Word correlations within these topics suggest that users perceive anxiety from overconsumption as a risk of edibles, while reduced anxiety and the absence of lung harm are perceived benefits. PBS appeared in topics such as Edible dosage and concentration and Frequency and tolerance breaks, indicating that users seek dosing advice and take tolerance breaks to manage effects.
Overall, the findings show that cannabis users recognize both risks and benefits of edible use. Perceived benefits include avoiding lung damage and reducing anxiety, while perceived risks center on anxiety from overconsumption. Users employ strategies such as dosage monitoring and tolerance breaks, though these may not effectively prevent adverse outcomes, especially given that people who use cannabis might lack adequate information on the cannabinoid content and evidence that tolerance breaks can sometimes increase hazardous use. Public health professionals could leverage these existing perceptions to develop health education campaigns and policies that prevent overuse and reduce episodes of acute anxiety associated with edible consumption
Microbial community characteristics predict thiamin availability in critical aquatic ecosystems
No full textThiamin (vitamin B1) is required by all living organisms as a coenzyme for central carbon metabolism. Aquatic microbes cycle thiamin and its chemically related congeners – thiamin-related compounds, or TRCs – in unique mechanisms depending on whether they de novo synthesize thiamin or supplement biosynthesis by salvaging TRCs (thiamin auxotrophs) from the extracellular environment. To study connections between microbial communities and TRCs, we paired TRC concentrations plus abiotic data with microbiome compositions in marine and freshwater ecosystems including the Sacramento River watershed, coastal California (CA), and Upper Klamath Basin. In addition to microbiome diversity, we analyzed microbial gene expression with metatranscriptomics and reference genome assemblies in Upper Klamath Basin. We found that thiamin concentrations in the Sacramento River were orders of magnitude lower than those of marine waters. Significant correlations were observed between the relative abundances of microbial taxa and concentrations of thiamin precursor compounds that indicated active biosynthesis, particularly in river hyporheic zones. Coastal CA ecosystems showed evidence that water chemical and physical properties associated with upwelling, such as density and oxygen content, influence how microbial communities cycle TRCs. In both systems, distinct ecological factors correlated with microbiome changes that altered the net exchange of TRCs. TRC concentrations in Upper Klamath Basin, which included measurements of the thiamin antimetabolite bacimethrin, increased concurrently with abundances of harmful algal bloom-forming cyanobacteria (cyanoHABs), implicating these taxa as thiamin producers. CyanoHAB species abundances also strongly correlated with bacimethrin concentrations. The expression of biogeochemically important gene pathways, including thiamin biosynthesis, also positively correlated with the abundance of cyanoHAB species. Across these studied ecosystems, our results are relevant to the health of thiamin-deficient salmonid fish, which may benefit from microbially sourced thiamin to mitigate their deficiency. Data from Upper Klamath Basin also uncovered a novel allelopathic mechanism that could be leveraged by cyanoHAB species to dominate eutrophic watersheds via the inhibition of thiamin auxotrophs in surface waters through bacimethrin production. Altogether, our results have improved our understanding of dissolved TRC distributions and microbial TRC cycling across previously unexplored ecosystems
Architecture, lifecycles, and fluxes of magmatic systems built during ignimbrite flare-ups constrained (mostly) by U-Pb zircon petrochronology
No full textShort periods of intense volcanic flux in continental arcs, known as flare-ups, exert significant leverage on the chemical and architectural evolution of Earth’s continental crust. Refining the characteristics of volcanic systems produced during flare-ups has direct implications for understanding the evolution of Earth’s crust and the production of voluminous ignimbrite eruptions. Numerous eruptions collectively erupted ~15000 km3 of silicic ignimbrite (dense rock equivalent, DRE) between ~10 – 1 Ma in the Altiplano-Puna Volcanic Complex (APVC) of northern Chile, defining an archetypal ignimbrite flare-up. At the central-western edge of the APVC at the foot of the modern volcanic arc, a series of extrusive lava domes and associated ignimbrites form Cerro Chaxas. Chaxas was previously ill-defined but was thought to have a protracted lifecycle between 8.35 – 4.00 Ma and is a potential source vent for the Puripicar supereruption (≥500 km3, dense rock equivalent). This Ph.D. dissertation provides resolution to the magmatic and volcanic history at Chaxas for the purpose of understanding the lifecycles and assemblage of large silicic systems, primarily through the lens of U-Pb petrochronology.
The first two chapters of this Ph.D dissertation deal with fundamentals of U-Pb data collection and reduction, as any interpretation is hinged on the quality of data and its collection. U-Pb geochronology of young zircons (≤10 Ma) is problematic due to non-normally distributed isotopes ratios stemming from low abundance of daughter isotopes; particularly 207Pb. This problem is addressed by treatment of 207Pb/206Pb with the Zero-Inflated Poisson (ZIP) distribution. This is found to improve U-Pb methodology by improving uncertainties on U-Pb dates by up to 12%, and 2% on average. Application of this methodology is available in the open-source software “LaserTRAMZ”, presented in the appendix. Second, objective-induced bias during in-situ spot selection is addressed by comparison of multiple U-Pb datasets and application of quantitative bias. Results show that the interpretation of magmatic systems may be strongly influenced by how spots are selected. Recommendations for generating an unbiased set of U-Pb zircon dates are given.
The third chapter utilizes geochronology and geology to constrain the general volcanology of the series of eruptions that collectively form what is coined here as the Chaxas Volcanic Complex. Eruptions at Chaxas initiated with the 5.49±0.15 Ma Agua Perdida Rhyolite and ended with the 1.22±0.11 Ma Final del Agua Rhyolite, redefining the lifecycle of the Chaxas Volcanic Complex. The source vent for the Puripicar ignimbrite is traced to the area beneath the modern volcanic arc adjacent to Cerro Chaxas. A series of young (~ 100 – 250 ka) lava flows that are stratigraphically above the silicic ignimbrite eruptions at the Chaxas Volcanic Complex form the basal platform to one of the densest volcano clusters in the Central Andes. These lava flows are interpreted as the products of remelted flare-up related intrusions mixed with younger mafic magmas. Results support that crustal priming during construction of large silicic systems promotes formation of volcano clusters that overprint primary spacing of vents in volcanic arcs.
The final two chapters of this dissertation deal with the effect of magmatic flux on the lifecycle and architecture of large silicic systems. Thermal modeling shows that fluxes were significantly higher early in the history of the Chaxas Volcanic Complex. Higher flux corresponds with eruptions that have protracted and complex crystallization histories in zircon as well as higher geochemical variation, whereas eruptions produced during lower flux conditions carry simpler crystal cargo that formed over shorter durations. This finding supports that high flux rates promote longer lifecycles of magma batches that allows them to become geochemically and thermally more complex than their short lived counterparts. Volumes of magmatic addition are also found to be substantially higher during the high-flux period, with >75% of the total volume of the magmatic system being emplaced during the build-up to the Puripicar eruption. Overall, these two chapters underscore that magmatic flux is the primary control on geochemical heterogeneity and architectural characteristics of magmatic systems that drive evolution of Earth’s crust
Eleanor Spears and the unanswered questions of progressivism
No full textEleanor Spears was a Progressive-Era activist who tirelessly worked for patriotic causes during World War I and helped deliver the message of women’s suffrage to her adopted residence of Little Falls, New York. She worked to elect Progressive candidates, presided over the Inglewood, CA branch of the Women’s Christian Temperance Union, headed her local parent-teacher association, and became a socialist. And yet this vibrant, talented woman is completely unknown, with only a small collection of extant papers and a few terse biographical records to show that she ever existed. I correct this historical invisibility by placing Spears in her proper context as an important figure in several local branches of Progressive movements in the twentieth century United States. Chapter 1 covers Eleanor’s early life and suffrage activism starting in 1915, when she joined the New York State Woman Suffrage Party and proved decisive for swinging her home county in favor of suffrage during the 1917 state referendum. I demonstrate Eleanor’s importance to the success of suffrage in Herkimer County, including her visits to rural hamlets and tireless publicity efforts. Chapter 2 explores the many other causes Eleanor became involved in from 1917-1923, including war stamp sales to help support the American government’s involvement in World War I, Red Cross work, and the Woman’s Christian Temperance Union. I
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demonstrate links between Eleanor’s various strands of volunteerism, her “maternalist” philosophy, and her involvement in Americanization work. Chapter 3 reviews Eleanor’s life and activism after her move to California. In it, I discuss her rapid political, social, and religious evolution to become a much different activist than she had been, while still maintaining points of contact with her past activist outlook.
Using a microhistorical methodology, I demonstrate that much of Eleanor’s activism centered around a “maternalist” philosophy of female involvement in the public sphere. I show the historical contradictions embodied in Eleanor’s simultaneous progressive and reactionary political stances, illuminate a picture of ground-level activism in several Progressive movements that Eleanor participated in, and provide further evidence for a “Long Progressive Era” that lasted far beyond a traditional end date of 1920
Trace element abundances in the Rock Canyon Anticline, Pueblo, Colorado, marine sedimentary section and their relationahip to Caribbean plateau construction and oxygen anoxic event 2
Get PDFRapid eruption of submarine lava flows during formation of the Caribbean plateau correlates closely with ocean anoxic event 2 (OAE2), which bracketed the Cenomanian/Turonian boundary (~93.5 Ma). These events also correspond with a positive excursion in carbon isotopic composition of seawater. Hydrothermal activity associated with large-scale submarine volcanism may have been responsible for this abrupt change in ocean chemistry. We determined the distribution of major, minor, and trace element abundances in the Rock Canyon marine sedimentary section (Pueblo, Colorado). After normalizing element concentrations to Zr to remove the variable contribution of terrigenous material to these sediments, we detected an interval of concentrated metal abundance anomalies that coincides with the abrupt beginning of the positive δ¹³C isotope excursion. The metal abundance anomalies indicate that intermittent hydrothermal activity, in the form of both water/rock exchange and magmatic degassing, introduced large concentrations of trace metals into the Cretaceous ocean at the same time that extinctions of benthic species, turnover in plankton communities, and increases in isotopically light organic carbon burial occurred. The stratigraphic position of this interval of trace metal anomalies matches events associated with OAE2 and indicates that intermittent hydrothermal activity on a massive scale triggered abrupt changes in carbon burial and deep ocean oxygen contents
The geochemistry of Atlantic hydrothermal particles
Get PDFParticles were collected from the dilute portion of neutrally buoyant hydrothermal plumes from four Mid-Atlantic Ridge sites (MARK, 23°N; TAG, 26°N; Broken Spur, 29°N; Lucky Strike, 37°N). Comparison of data from proximal portions of the TAG (Atlantic) [German et al., 1991; this study] and North Cleft (Pacific) [Freely et al., 1994] plumes show that oxyanion (e.g., V) is more efficient at TAG, possibly due to a higher proportion of Fe removed as sulfides at North Cleft and/or the more vigorous mixing in the high energy TAG buoyant plume. Chalcophile elements (e.g., Cu) show two stage removal. They are precipitated as sulfides during initial mixing of vent fluids with seawater and are sedimented from the buoyant plume. In the dilute plume they are scavenged from seawater by Fe oxyhydroxides. The REE show continued scavenging in the neutrally buoyant plume and lower levels in 1993 samples compared to 1988 samples [German et al., 1990] suggesting that the amount of scavenging is related to particle recycling.Copyrighted by American Geophysical Union
An optical technique for the measurement of longshore currents
Get PDFWe present an optical method (optical current meter) to measure the longshore
component of nearshore surface currents by measuring the alongshore drift of persistent
sea foam in the surf zone. The method uses short time series of video data collected from
an alongshore array of pixels. These space-time data are first Fourier transformed to a
frequency-wave number spectrum and, finally, to a velocity spectrum. A model of the
velocity spectrum is fit to the observed spectrum to estimate the foam drift velocity.
Confidence intervals and other measures of the input and output data quality are
calculated. Field test comparisons were made against an in situ bidirectional
electromagnetic current meter on the basis of 1 month of video data from the 1997 Sandy
Duck field experiment. The root mean square error between the two approaches was
0.10 m/s. Linear regression analysis showed the gain between the two instruments to not be
statistically different from one. Differences between the surface and interior measurements
were compared to forcing mechanisms that may cause surface velocity shear. Velocity
offsets and alongshore wind stress were well correlated for cases when waves and wind
were not aligned to within ±45°, when wind- and wave-forced currents are reasonably
separable. Calculated wind-dependent surface current shear, modeled as a surface boundary
layer, correlated well with the observed velocity offsets for observations of nonalignment
between wind and waves. This technique can be applied to study large-scale coastal
behavior
Estimates of sea surface height and near-surface alongshore coastal currents from combinations of altimeters and tide gauges
Get PDFPresent methods used to retrieve altimeter data do not provide reliable estimates of
sea surface height (SSH) in the nearshore region, resulting in a measurement gap of
25–50 km next to the coast. In the present work, gridded SSH fields produced by
Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO) in the
offshore region are combined with coastal tide gauge time series of SSH to improve
estimation in that gap along the west coast of the United States in the northern California
Current System between 40° and 45°N and 123.8° and 126°W. To assess the increase
in skill provided by this procedure, the geostrophic alongshore currents, calculated from
the new SSH fields in the gap region, are compared to three in situ, nearshore current
measurements, resulting in correlation coefficients of 0.73–0.83 and standard deviations
of the differences of 11.6–12.6 cm/s, substantially improved from the AVISO-only results.
When the Ekman current components are estimated and added to the geostrophic
currents, comparisons to the 10 m deep acoustic Doppler current profiler velocities are
only slightly improved. The Ekman components make a more significant contribution
when compared to HF radar surface current measurements, providing correlations of
0.94 and standard deviations of the differences of 6.4–9.5 cm/s. These results represent a
dramatic improvement in the quality of the SSH fields and estimated alongshore
currents when additional, realistic SSH data from the coastal region are added.
Here we use coastal tide gauges to provide the additional SSH data but also discuss more
general approaches for altimeter SSH retrievals in coastal regions where tide
gauge data are not available
Time-dependent, wind-driven flow over a shadow midshelf submarine bank
Get PDFDuring summer 2001, high-resolution hydrographic, velocity, and bio-optical surveys
were conducted over Heceta Bank off central Oregon. North of the bank, upwelling
over simple bottom topography exhibited a classic response with a midshelf, baroclinic
coastal jet and upwelled isopycnals. The coastal upwelling jet follows the bank
topography as it widens offshore before reaching the southern end of the bank, where the
shelf break turns almost 90° back toward the coast. The ensuing adjustment involves the
offshelf transport of coastal water and the material it contains. The jet meanders
anticyclonically in the ‘‘lee’’ of the bank before resuming its equatorward path seaward of
the shelf break. A pool of high-chlorophyll (>15 mg m¯³) near-surface water is found in
the low-velocity ‘‘lee’’ region created by the bank. A low-temperature, high-salinity
bottom water pool, supplied primarily from the south, lies over the inshore region of the
bank. This bottom pool is up to 40 m thick and contains elevated levels of
suspended material. By creating an east-west perturbation in the coastal upwelling front,
the flow-topography interaction introduces an alongshore pressure gradient. When
southward upwelling-favorable winds relax, this alongshore pressure gradient can drive
flow back to the north. This leads to northward flow on the inshore side of the bank,
ultimately setting up the potential for recirculation around the entire bank complex on a
timescale of about 10 days. Strong northward winds during summer lead to downwelling
within 15 km of the coast, accompanied by significant (>0.2 m s¯¹) wind-driven
northward currents
Composition and major sources of organic compounds of aerosol particulate matter sampled during the ACE-Asia campaign
Get PDFThe organic compound tracers of atmospheric particulate matter, as well as organic carbon (OC) and elemental carbon (EC), have been characterized for samples acquired during the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) from Gosan, Jeju Island, Korea, from Sapporo, Japan, and from Chichi-jima Island in the western North Pacific, as well as on the National Oceanic and Atmospheric Administration R/V Ronald H. Brown. Total extracts were analyzed by gas chromatography–mass spectrometry to determine both polar and aliphatic compounds. Total particles, organic matter, and lipid and saccharide compounds were high during the Asian dust episode (early April 2001) compared to levels at other times. The organic matter can be apportioned to seven emission sources and to significant oxidationproducing secondary products during long-range transport. Terrestrial natural background compounds are vascular plant wax lipids derived from direct emission and as part of desert sand dust. Fossil fuel utilization is obvious and derives from petroleum product and coal combustion emissions. Saccharides are a major polar (water-soluble) carbonaceous fraction derived from soil resuspension (agricultural activities). Biomass-burning smoke is evident in all samples and seasons. It contributes up to 13% of the total compound mass as water-soluble constituents. Burning of refuse is another source of organic particles. Varying levels of marine-derived lipids are superimposed during aerosol transport over the ocean. Secondary oxidation products increase with increasing transport distance and time. The ACE-Asia aerosols are composed not only of desert dust but also of soil dust, smoke from biomass and refuse burning, and emissions from fossil fuel use in urban areas