Public Perceptions and Discussions of the US Food and Drug Administration's JUUL Ban Policy on Twitter: Observational Study.

BACKGROUND: On June 23, 2022, the US Food and Drug Administration announced a JUUL ban policy, to ban all vaping and electronic cigarette products sold by Juul Labs. OBJECTIVE: This study aims to understand public perceptions and discussions of this policy using Twitter (subsequently rebranded as X) data. METHODS: Using the Twitter streaming application programming interface, 17,007 tweets potentially related to the JUUL ban policy were collected between June 22, 2022, and July 25, 2022. Based on 2600 hand-coded tweets, a deep learning model (RoBERTa) was trained to classify all tweets into propolicy, antipolicy, neutral, and irrelevant categories. A deep learning model (M3 model) was used to estimate basic demographics (such as age and gender) of Twitter users. Furthermore, major topics were identified using latent Dirichlet allocation modeling. A logistic regression model was used to examine the association of different Twitter users with their attitudes toward the policy. RESULTS: Among 10,480 tweets related to the JUUL ban policy, there were similar proportions of propolicy and antipolicy tweets (n=2777, 26.5% vs n=2666, 25.44%). Major propolicy topics included "JUUL causes youth addition," "market surge of JUUL," and "health effects of JUUL." In contrast, major antipolicy topics included "cigarette should be banned instead of JUUL," "against the irrational policy," and "emotional catharsis." Twitter users older than 29 years were more likely to be propolicy (have a positive attitude toward the JUUL ban policy) than those younger than 29 years. CONCLUSIONS: Our study showed that the public showed different responses to the JUUL ban policy, which varies depending on the demographic characteristics of Twitter users. Our findings could provide valuable information to the Food and Drug Administration for future electronic cigarette and other tobacco product regulations.

Relationship Between Product Features and the Prices of e-Cigarette Devices Sold in Web-Based Vape Shops: Comparison Study Using a Linear Regression Model.

BACKGROUND: Open-system electronic cigarette (EC) product features, such as battery capacity, maximum output wattage, and so forth, are major components that drive product costs and may influence use patterns. Moreover, continued innovation and monitoring of product features and prices will provide critical information for designing appropriate taxation policies and product regulations. OBJECTIVE: This study will examine how product features are associated with the prices of devices sold in web-based vape shops. METHODS: We draw samples from 5 popular, US-based, web-based vape shops from April to August 2022 to examine starter kits, device-only products, and e-liquid container-only products. We implemented a linear regression model with a store-fixed effect to examine the association between device attributes and prices. RESULTS: EC starter kits or devices vary significantly by type, with mod prices being much higher than pod and vape pen prices. The prices of mod starter kits were even lower than those of mod devices, suggesting that mod starter kits are discounted in web-based vape shops. The price of mod kits, mod device-only products, and pod kits increased as the battery capacity and output wattage increased. For vape pens, the price was positively associated with the volume size of the e-liquid container. On the other hand, the price of pod kits was positively associated with the number of containers. CONCLUSIONS: A unit-based specific tax, therefore, will impose a higher tax burden on lower-priced devices such as vape pens or pod systems and a lower tax burden on mod devices. A volume- or capacity-based specific tax on devices will impose a higher tax burden on vape pens with a larger container size. Meanwhile, ad valorem taxes pegged to wholesale or retail prices would apply evenly across device types, meaning those with advanced features such as higher battery capacities and output wattage would face higher rates. Therefore, policy makers could manipulate tax rates by device type to discourage the use of certain device products.

Brillouin Klein space and half-turn space in three-dimensional acoustic crystals.

The Bloch band theory and Brillouin zone (BZ) that characterize wave-like behaviors in periodic mediums are two cornerstones of contemporary physics, ranging from condensed matter to topological physics. Recent theoretical breakthrough revealed that, under the projective symmetry algebra enforced by artificial gauge fields, the usual two-dimensional (2D) BZ (orientable Brillouin two-torus) can be fundamentally modified to a non-orientable Brillouin Klein bottle with radically distinct manifold topology. However, the physical consequence of artificial gauge fields on the more general three-dimensional (3D) BZ (orientable Brillouin three-torus) was so far missing. Here, we theoretically discovered and experimentally observed that the fundamental domain and topology of the usual 3D BZ can be reduced to a non-orientable Brillouin Klein space or an orientable Brillouin half-turn space in a 3D acoustic crystal with artificial gauge fields. We experimentally identify peculiar 3D momentum-space non-symmorphic screw rotation and glide reflection symmetries in the measured band structures. Moreover, we experimentally demonstrate a novel stacked weak Klein bottle insulator featuring a nonzero Z2 topological invariant and self-collimated topological surface states at two opposite surfaces related by a nonlocal twist, radically distinct from all previous 3D topological insulators. Our discovery not only fundamentally modifies the fundamental domain and topology of 3D BZ, but also opens the door towards a wealth of previously overlooked momentum-space multidimensional manifold topologies and novel gauge-symmetry-enriched topological physics and robust acoustic wave manipulations beyond the existing paradigms.

Cost Comparison and Spending on Tobacco Products: Evidence from A Nationally Representative Sample of Adult E-Cigarette Users.

Background: Over 20 states and local jurisdictions in the U.S. have imposed e-cigarette taxes. It is important to evaluate how adult vapers, including those who also smoke respond to e-cigarette taxation. The purpose of this study is to examine factors associated with adult vapers' cost perception of e-cigarettes relative to cigarettes and budget allocations between two products. Methods: We recruited a nationally representative sample of 801 adult e-cigarette users in the U.S., who participated in an online survey in April and May 2023. Nested-ordered logit models and ordinary least squares regressions were used in the analysis. Results: On average, monthly e-cigarette spending was $82.22, and cigarette spending was $118.77 among dual users. Less frequent e-cigarette use and higher state-level e-cigarette taxes were associated with perceiving smoking as cheaper than vaping. Age and exclusive use of tank systems were associated with perceiving vaping as cheaper than smoking. Exclusive use of tank systems was also associated with lower e-cigarette spending. Adults who used e-cigarettes more frequently preferred to report weekly budget on e-cigarettes ( p < 0.01), and among dual users, everyday smokers preferred to report weekly (versus monthly) budget on cigarettes compared to someday smokers ( p < 0.001). Conclusion: Among US adult vapers, frequencies of tobacco use and e-cigarette device type are closely related to cost measures; and e-cigarette taxes are associated with cost perception of e-cigarettes relative to cigarettes, suggesting potential financial disincentive for vaping. Policymaker may consider imposing differential taxes by e-cigarette product types due to their different costs to consumers.

Phylogenomics reveal Populusgonggaensis as a hybrid between P.lasiocarpa and P.cathayana (Salicaceae).

High levels of intra-specific polymorphism and frequent hybridisation make it difficult to define species and correctly apply their scientific names. Populus L. is a challenging genus with plentiful natural and artificial hybrids. This study is a part of the project 'Flora of Pan-Himalaya' and aims to determine the taxonomic identity of P.gonggaensis N. Chao & J.R. He and to find out whether it is of hybrid origin. Whole-genome sequencing data were obtained from 57 samples. The SNP matrix was developed for phylogenetic reconstruction, ABBA-BABA statistics, PCA and ADMIXTURE analysis. The results indicate that P.gonggaensis is a spontaneous hybrid between P.lasiocarpa and P.cathayana. This study points out the importance of SNP data and comprehensive analyses for discovering the potential interspecific hybridisation and clarifies the usage of the name. In addition, the lectotype of P.gonggaensis was designated.

How to Identify e-Cigarette Brands Available in the United States During 2020-2022: Development and Usability Study.

BACKGROUND: Prior studies have demonstrated that the e-cigarette market contains a large number of brands. Identifying these existing e-cigarette brands is a key element of market surveillance, which will further assist in policy making and compliance checks. OBJECTIVE: To facilitate the surveillance of the diverse product landscape in the e-cigarette market, we constructed a semantic database of e-cigarette brands that have appeared in the US market as of 2020-2022. METHODS: In order to build the brand database, we searched and compiled e-cigarette brands from a comprehensive list of retail channels and sources, including (1) e-liquid and disposable brands sold in web-based stores, (2) e-cigarette brands sold in brick-and-mortar stores and collected by the Nielsen Retail Scanner Data, (3) e-cigarette brands compiled by Wikipedia, (4) self-reported e-cigarette brands from the 2020 International Tobacco Control Four-Country Smoking and Vaping (ITC 4CV) US survey, and (5) e-cigarette brands on Twitter. We also estimated the top 5 e-cigarette brands by sales volume in brick-and-mortar stores, by the frequency and variety of offerings in web-based shops, and by the frequency of self-reported brands from the 2020 ITC 4CV US survey. RESULTS: As of 2020-2022, a total of 912 e-cigarette brands have been sold by various retail channels. During 2020-2022, the top 5 brands are JUUL, vuse, njoy, blu, and logic in brick-and-mortar stores; blu, king, monster, twist, and air factory for e-liquids in web-based stores; hyde, pod mesh, suorin, vaporlax, and xtra for disposables sold in web-based stores; and smok, aspire, vaporesso, innokin, and eleaf based on self-reported survey data. CONCLUSIONS: As the US Food and Drug Administration enforces the premarket tobacco market authorization, many e-cigarette brands may become illegal in the US market. In this context, how e-cigarette brands evolve and consolidate in different retail channels will be critical for understanding the regulatory impacts on product availability. Our semantic database of e-cigarette brands can serve as a useful tool to monitor product and marketplace development, conduct compliance checks, assess manufacturers' marketing behaviors, and identify regulatory impacts.

The association between excise taxes and smoking and vaping transitions-Findings from the 2016-2020 ITC United States surveys.

BACKGROUND: While a growing number of studies examined the effect of e-cigarette (EC) excise taxes on tobacco use behaviors using cross-sectional surveys or sales data, there are currently no studies that evaluate the impact of EC taxes on smoking and vaping transitions. METHODS: Using data from the US arm of the 2016-2020 International Tobacco Control Four Country Smoking and Vaping Survey (ITC 4CV), we employed a multinomial logit model with two-way fixed effects to simultaneously estimate the impacts of cigarette/EC taxes on the change in smoking and vaping frequencies. RESULTS: Our benchmark model suggests that a 10 % increase in cigarette taxes led to an 11 % reduction in smoking frequencies (p < 0.01), while EC taxes did not have a significant effect on smoking frequencies. CONCLUSION: Our findings suggest that increasing cigarette taxes may serve as an effective means of encouraging people who smoke to cut back on smoking or quit smoking. The impact of increasing EC taxes on smoking transitions is less certain at this time.

Observation of Period-Doubling Bloch Oscillations.

Bloch oscillations refer to the periodic oscillation of a wave packet in a lattice under a constant force. Typically, the oscillation has a fundamental period that corresponds to the wave packet traversing the first Brillouin zone once. Here, we demonstrate, both theoretically and experimentally, the optical Bloch oscillations where the wave packet must traverse the first Brillouin zone twice to complete a full cycle, resulting in a period of oscillation that is 2 times longer than that of usual Bloch oscillations. The unusual Bloch oscillations arise due to the band crossing of valley-Hall topological edge states at the Brillouin boundary for zigzag domain walls between two staggered honeycomb lattices with inverted on-site energy detuning, which are protected by the glide-reflection symmetry of the underlying structures. Our work sheds light on the direct detection of band crossings resulting from intrinsic symmetries that extend beyond the fundamental translational symmetry in topological systems.

Observation of a Higher-Order End Topological Insulator in a Real Projective Lattice.

The modern theory of quantized polarization has recently extended from 1D dipole moment to multipole moment, leading to the development from conventional topological insulators (TIs) to higher-order TIs, i.e., from the bulk polarization as primary topological index, to the fractional corner charge as secondary topological index. The authors here extend this development by theoretically discovering a higher-order end TI (HOETI) in a real projective lattice and experimentally verifying the prediction using topolectric circuits. A HOETI realizes a dipole-symmetry-protected phase in a higher-dimensional space (conventionally in one dimension), which manifests as 0D topologically protected end states and a fractional end charge. The discovered bulk-end correspondence reveals that the fractional end charge, which is proportional to the bulk topological invariant, can serve as a generic bulk probe of higher-order topology. The authors identify the HOETI experimentally by the presence of localized end states and a fractional end charge. The results demonstrate the existence of fractional charges in non-Euclidean manifolds and open new avenues for understanding the interplay between topological obstructions in real and momentum space.

How do users compare the costs between nicotine vaping products and cigarettes? Findings from the 2016-2020 International Tobacco Control United States surveys.

BACKGROUND AND AIMS: Nicotine vaping products (NVPs) can potentially help adult tobacco users quit smoking. This study evaluated how adult consumers compare the costs between NVPs and cigarettes. METHOD: We used data from the US arm of the 2016-2020 International Tobacco Control Four Country Smoking and Vaping (ITC 4CV) surveys to perform a multinomial logit model with two-way fixed effects to measure how perceived cost comparisons are associated with NVP and cigarette taxes, use patterns, NVP device types and individual sociodemographic factors. RESULTS: Higher cigarette taxes are associated with a greater likelihood of perceiving NVPs and cigarettes as costing the same for the overall population and among people who exclusively smoke, and a lower likelihood of perceiving NVPs as more expensive among people who exclusively vape, compared with lower cigarette taxes. Pre-filled cartridge and tank users are more likely to perceive NVPs as less expensive than cigarettes, compared with people who use other types of NVPs. The associations between taxes and perceived cost comparison were more pronounced among males, younger and low-income populations. CONCLUSIONS: Higher cigarette taxes are associated with perceived financial incentives for nicotine vaping products (NVPs) over cigarettes, whereas NVP taxes are not associated with perceived cost comparison between NVPs and cigarettes.

Use of Machine Learning Tools in Evidence Synthesis of Tobacco Use Among Sexual and Gender Diverse Populations: Algorithm Development and Validation.

BACKGROUND: From 2016 to 2021, the volume of peer-reviewed publications related to tobacco has experienced a significant increase. This presents a considerable challenge in efficiently summarizing, synthesizing, and disseminating research findings, especially when it comes to addressing specific target populations, such as the LGBTQ+ (lesbian, gay, bisexual, transgender, queer, intersex, asexual, Two Spirit, and other persons who identify as part of this community) populations. OBJECTIVE: In order to expedite evidence synthesis and research gap discoveries, this pilot study has the following three aims: (1) to compile a specialized semantic database for tobacco policy research to extract information from journal article abstracts, (2) to develop natural language processing (NLP) algorithms that comprehend the literature on nicotine and tobacco product use among sexual and gender diverse populations, and (3) to compare the discoveries of the NLP algorithms with an ongoing systematic review of tobacco policy research among LGBTQ+ populations. METHODS: We built a tobacco research domain-specific semantic database using data from 2993 paper abstracts from 4 leading tobacco-specific journals, with enrichment from other publicly available sources. We then trained an NLP model to extract named entities after learning patterns and relationships between words and their context in text, which further enriched the semantic database. Using this iterative process, we extracted and assessed studies relevant to LGBTQ+ tobacco control issues, further comparing our findings with an ongoing systematic review that also focuses on evidence synthesis for this demographic group. RESULTS: In total, 33 studies were identified as relevant to sexual and gender diverse individuals' nicotine and tobacco product use. Consistent with the ongoing systematic review, the NLP results showed that there is a scarcity of studies assessing policy impact on this demographic using causal inference methods. In addition, the literature is dominated by US data. We found that the product drawing the most attention in the body of existing research is cigarettes or cigarette smoking and that the number of studies of various age groups is almost evenly distributed between youth or young adults and adults, consistent with the research needs identified by the US health agencies. CONCLUSIONS: Our pilot study serves as a compelling demonstration of the capabilities of NLP tools in expediting the processes of evidence synthesis and the identification of research gaps. While future research is needed to statistically test the NLP tool's performance, there is potential for NLP tools to fundamentally transform the approach to evidence synthesis.

The Association Between the License Fee Increase and the Density of Tobacco Retailers in California-A Segmented Interrupted Time-Series Analysis by Income and Race/Ethnicity.

INTRODUCTION: On May 9, 2016, the State of California passed a law to increase the licensing fee for tobacco retailers from a one-time-only fee of $100 to an annual fee of $265, effective on June 9, 2016. This study investigates the association between this fee increase and retailer densities by neighborhood income and race/ethnicity characteristics. METHODS: We obtained quarterly data on the number of active tobacco retailer licenses from 2011 to 2020 in every zip code in California from the California Department of Tax and Fee Administration. These data were then linked to zip code-level income, race/ethnicity, and population measures. We used a single-group segmented interrupted time-series analysis to assess the association between the increase in licensing fees and retailer densities by neighborhood income and race/ethnicity. RESULTS: After the implementation of the annual licensing fees, the retailer density decreased both immediately and gradually. Specifically, the retailer density dropped by 0.47 in the first quarter following the intervention. Compared to the pre-intervention time trend, the retailer density decreased quarterly by 0.05. Furthermore, the impacts of increasing licensing fees were more pronounced in low-income and the majority Black zip codes. CONCLUSIONS: Given that higher smoking prevalence is associated with greater tobacco outlet density, the licensing fee increase could be an effective policy tool to reduce tobacco use among economically disadvantaged and minority Black communities, thereby addressing tobacco-use disparities. IMPLICATIONS: This study used the single-group segmented interrupted time-series analysis to assess the association between the licensing fee increase and tobacco retailer densities by neighborhood income and race/ethnicity. We found that this licensing fee increase was associated with reduced retailer densities and the total number of active retailers right after the implementation. We further found that the annual licensing fee policy had a continuous effect in reducing tobacco retailer densities in all zip codes. The impacts of increasing licensing fees were more pronounced in low-income and majority of Black zip codes.

Soft Biomimetic Fiber-Optic Tactile Sensors Capable of Discriminating Temperature and Pressure.

Tactile sensors with high softness and multisensory functions are highly desirable for applications in humanoid robotics, smart prosthetics, and human-machine interfaces. Here, we report a soft biomimetic fiber-optic tactile (SBFT) sensor that offers skin-like tactile sensing abilities to perceive and discriminate temperature and pressure. The SBFT sensor is fabricated by encapsulating a macrobent fiber Bragg grating (FBG) in an elastomeric droplet-shaped structure that results in two optical resonances associated with the FBG and excited whispering gallery modes (WGMs) propagating along the bent region. Benefiting from the different thermo-optic and stress-optic effects of FBG and WGM resonances, the pressure and temperature can be fully decoupled with a high precision of 0.2 °C and 0.8 mN, respectively. To achieve a compact system for signal demodulation, a single-cavity dual-comb fiber laser is developed to interrogate the SBFT sensor based on dual-comb spectroscopy, which enables fast spectral sampling with a single photodiode. We show that the SBFT sensor is capable of perceiving pressure, temperature, and hardness in touching soft tissues and human skins, demonstrating great promise for soft tissue palpation and human-like robotic perception.

How cigarette excise tax pass-through to prices responds to the uptake and evolution of e-cigarettes (ECs).

BACKGROUND: How excise taxes are passed through to prices determines whether tax policies will be effective in changing smoking behaviours. Though previous literature has documented that cigarette taxes are overly shifted to prices, there is limited evidence on how cigarette tax pass-through to prices is affected by the uptake and evolution of e-cigarettes (ECs) in the US market. OBJECTIVE: This study investigates how cigarette excise tax pass-through rate varied by price levels (the 25th, 50th, and 75th percentile prices) and the uptake and evolution of ECs. METHODS: Tax pass-through rates were assessed using ordinary least squares regressions while controlling for state, year and month fixed effects. Different trends were then tested for the pre-EC uptake era (2006-2011), EC uptake era (2012-2016) and the evolution of nicotine salt-based ECs era (2017 and later). FINDINGS: Cigarette excise taxes were fully shifted to the 25th and 50th percentile prices and overly shifted to the 75th percentile prices at a 1:1.1 rate. While cigarette excise taxes had a continuous impact on raising prices, the tax pass-through rates were lower for lower priced cigarettes, and states imposed lower taxes. CONCLUSIONS: Continuing to raise cigarette taxes may be needed to create financial incentives to encourage people who smoke to switch to ECs. In addition, continuing to raise cigarette taxes and additional pricing policies such as price promotion restrictions are needed to increase retail prices and reduce price minimisation opportunities.

Tobacco purchasing in Australia during regular tax increases: findings from the International Tobacco Control Policy Evaluation Project.

OBJECTIVE: We examined Australian tobacco purchasing trends, the average self-reported price paid within each purchase type and the association between type of tobacco product purchased and participant characteristics, including quit intentions, between 2007 and 2020. METHODS: We analysed data collected from adults who smoked factory-made and/or roll-your-own (RYO) cigarettes in nine waves (2007-2020) of the International Tobacco Control Policy Evaluation Project Australia Survey (nsample=5452, nobservations=11 534). The main outcome measures were type of tobacco products purchased: RYO, carton, pack or pouch size and brand segment. Logistic regression, fit using generalised estimating equations, was estimated the association between the outcome and participant characteristics. RESULTS: The reported price-minimising purchasing patterns increased from 2007 to 2020: any RYO (23.8-43.9%), large-sized pack (2007: 24.0% to 2016: 34.3%); shifting from large-sized to small-sized packs (2020: 37.7%), and economy brand (2007: 37.2% to 2020: 59.3%); shifting from large (2007: 55.8%) to small economy packs (2014: 15.3% to 2020: 48.1%). Individuals with a lower income, a higher nicotine dependence level and no quit intention were more likely to purchase RYO and large-sized packs. CONCLUSION: RYO, large-sized packs and products with a low upfront cost (eg, small RYO pouches and small-sized economy brand packs) may appeal to people on low incomes. Australia's diverse tobacco pack and pouch sizes allow the tobacco industry to influence tobacco purchases. Standardising pack and pouch sizes may reduce some price-related marketing and especially benefit people who have a low income, are highly addicted and have no quit intention.

Synthetic nicotine e-liquids sold in US online vape shops.

Synthetic nicotine (relative to tobacco-derived, or "natural" nicotine) is an emerging feature of e-cigarettes including e-liquids in the online marketplace. This study investigated a total of 11,161 unique nicotine e-liquids sold in online stores in the US during 2021, using keyword matching approach to identify the feature of synthetic nicotine based on product description texts. We showed that in 2021, 2.13% of nicotine-containing e-liquids in our sample were marketed as synthetic nicotine e-liquids. About a quarter of the synthetic nicotine e-liquids that we identified were salt-based; the nicotine strength varied; and those synthetic nicotine e-liquids had a variety of flavor profiles. Synthetic nicotine containing e-cigarettes are likely to remain in the market and manufacturers might market those products as "tobacco-free," to attract consumers who this feature as healthier or less addictive. It is important to monitor synthetic nicotine in the e-cigarette marketplace and assess how this feature influences consumer behaviors.

What types of e-liquid products were more likely to offer price promotions?

INTRODUCTION: The present study empirically examined the association between price discounts and product attributes of e-liquids sold by online retailers. METHODS: We analysed 14 000 e-liquid products from five major online e-cigarette retailers between April and May 2021 to determine the association between price discounts and product attributes such as nicotine level and form, flavour and vegetable glycerine/propylene glycol ratio. A fixed-effects model was used in the analysis and discounts were calculated in US cents/mL of e-liquid volume. RESULTS: Out of 14 407 e-liquid products, 92.5% were offered at a discounted price. On average, the price discount for the 13 324 products that had discounts was 16.84 cents/mL across the five stores. Among the three forms of nicotine (salt, freebase and nicotine free), salt e-liquids had the highest average price discount. CONCLUSION: Our findings suggest that e-liquids with salt nicotine have a higher average price discount when sold online, which may influence consumer purchasing behaviour. Further research is needed to assess the potential impact of these discounts on youth and adult tobacco use. Policymakers may consider implementing measures to limit online price discounts for e-liquids as a means of reducing sales among young people.

Recency measures matter: Variability in reported last use of tobacco and marijuana products among a nationally representative study of U.S. young adults.

INTRODUCTION: Current use of tobacco and marijuana products is largely defined as use within the past 30-days or more recently. These products are not used in the same manner, frequency, or context especially among young adults who are increasingly at risk for poly-product use. The purpose of this study was to examine patterns of most recent product use across select tobacco and marijuana products. MATERIALS AND METHODS: Data used in this study come from a cross-sectional survey conducted among a nationally representative sample of young adults ages 18-34 (n = 1,189) in the U.S. from October-November 2020. Respondents were asked about past product and most recent use of select tobacco/nicotine products (cigarettes, little filtered cigars and cigarillos, large cigars, e-cigarettes, hookah/water pipes) and marijuana products (blunts, e-cigarettes with marijuana, and other products with marijuana). RESULTS: A high proportion of young adults reported having used at least one tobacco (79.6%) or marijuana (68.6%) products. There is variability in the distribution of most recent use across different tobacco and marijuana users even within the past 3 to past 6 months where nearly one in five users of any product report last use. The average number of tobacco/nicotine products used as well as concurrent marijuana use were lowest when looking at those whose most recent use was within the past 30-days. As the measures of most recent use became more broad, the number of tobacco/nicotine products used increased as did the prevalence of concurrent marijuana use which extended through the past 6-months. CONCLUSION: Measures of current use may need to be expanded beyond the past 30-days to include through the past 6-months to better encapsulate usage patterns when considering poly-tobacco and marijuana co-use.

The associations between e-liquid characteristics and its pricing: Evidence from online vape shops.

Given the increase in electronic cigarette use during the past decade, the objectives of this study are to obtain comprehensive product-level information from online vape shops, which are one of the most common outlets for e-cigarette users to purchase vaping products, especially e-liquid products, and to examine the appeal of various e-liquid product attributes to consumers. We used web scraping and estimation of generalized estimating equation (GEE) models to obtain and analyze data from five popular online vape shops that sell nationwide across the US. The outcome measures are e-liquid pricing for the following e-liquid product attributes: nicotine concentration (in mg/ml), nicotine form (nicotine-free, freebase, or salt), vegetable glycerin/propylene glycol (VG/PG) ratio, and a variety of flavors. We find that the pricing for freebase nicotine and nicotine salt products are 1% (p<0.001) lower and 12% higher (p<0.001), respectively, than that for products that do not contain nicotine. For nicotine salt-based e-liquid products specifically, the pricing for a 50/50 VG/PG ratio is 10% (p<0.001) higher than the pricing for a more common 70/30 VG/PG ratio, and the pricing for fruity flavors is 2% (p<0.05) higher than that for tobacco/unflavored products. Regulating the nicotine form in all e-liquid products and fruity flavor in nicotine salt-based products will have a great impact on the market and consumers. The preference for VG/PG ratio varies by product nicotine form. More evidence on typical user patterns of a certain nicotine form (i.e., freebase or salt nicotine) is needed to assess the public health consequences of these regulations.

Evolutionary origin and establishment of a dioecious diploid-tetraploid complex.

Polyploids recurrently emerge in angiosperms, but most polyploids are likely to go extinct before establishment due to minority cytotype exclusion, which may be specifically a constraint for dioecious plants. Here we test the hypothesis that a stable sex-determination system and spatial/ecological isolation facilitate the establishment of dioecious polyploids. We determined the ploidy levels of 351 individuals from 28 populations of the dioecious species Salix polyclona, and resequenced 190 individuals of S. polyclona and related taxa for genomic diversity analyses. The ploidy survey revealed a frequency 52% of tetraploids in S. polyclona, and genomic k-mer spectra analyses suggested an autopolyploid origin for them. Comparisons of diploid male and female genomes identified a female heterogametic sex-determining factor on chromosome 15, which probably also acts in the dioecious tetraploids. Phylogenetic analyses revealed two diploid clades and a separate clade/grade of tetraploids with a distinct geographic distribution confined to western and central China, where complex mountain systems create higher levels of environmental heterogeneity. Fossil-calibrated phylogenies showed that the polyploids emerged during 7.6-2.3 million years ago, and population demographic histories largely matched the geological and climatic history of the region. Our results suggest that inheritance of the sex-determining system from the diploid progenitor as intrinsic factor and spatial isolation as extrinsic factor may have facilitated the preservation and establishment of polyploid dioecious populations.