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"Nowak, Sarah"
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Comparing covariation among vaccine hesitancy and broader beliefs within Twitter and survey data
Over the past decade, the percentage of adults in the United States who use some form of social media has roughly doubled, increasing from 36 percent in early 2009 to 72 percent in 2019. There has been a corresponding increase in research aimed at understanding opinions and beliefs that are expressed online. However, the generalizability of findings from social media research is a subject of ongoing debate. Social media platforms are conduits of both information and misinformation about vaccines and vaccine hesitancy. Our research objective was to examine whether we can draw similar conclusions from Twitter and national survey data about the relationship between vaccine hesitancy and a broader set of beliefs. In 2018 we conducted a nationally representative survey of parents in the United States informed by a literature review to ask their views on a range of topics, including vaccine side effects, conspiracy theories, and understanding of science. We developed a set of keyword-based queries corresponding to each of the belief items from the survey and pulled matching tweets from 2017. We performed the data pull of the most recent full year of data in 2018. Our primary measures of belief covariation were the loadings and scores of the first principal components obtained using principal component analysis (PCA) from the two sources. We found that, after using manually coded weblinks in tweets to infer stance, there was good qualitative agreement between the first principal component loadings and scores using survey and Twitter data. This held true after we took the additional processing step of resampling the Twitter data based on the number of topics that an individual tweeted about, as a means of correcting for differential representation for elicited (survey) vs. volunteered (Twitter) beliefs. Overall, the results show that analyses using Twitter data may be generalizable in certain contexts, such as assessing belief covariation.
Journal Article
Optimal non-pharmaceutical pandemic response strategies depend critically on time horizons and costs
The COVID-19 pandemic has called for swift action from local governments, which have instated non-pharmaceutical interventions (NPIs) to curb the spread of the disease. The swift implementation of social distancing policies has raised questions about the costs and benefits of strategies that either aim to keep cases as low as possible (suppression) or aim to reach herd immunity quickly (mitigation) to tackle the COVID-19 pandemic. While curbing COVID-19 required blunt instruments, it is unclear whether a less-transmissible and less-deadly emerging pathogen would justify the same response. This paper illuminates this question using a parsimonious transmission model by formulating the social distancing lives vs. livelihoods dilemma as a boundary value problem using calculus of variations. In this setup, society balances the costs and benefits of social distancing contingent on the costs of reducing transmission relative to the burden imposed by the disease. We consider both single-objective and multi-objective formulations of the problem. To the best of our knowledge, our approach is distinct in the sense that strategies emerge from the problem structure rather than being imposed a priori. We find that the relative time-horizon of the pandemic (i.e., the time it takes to develop effective vaccines and treatments) and the relative cost of social distancing influence the choice of the optimal policy. Unsurprisingly, we find that the appropriate policy response depends on these two factors. We discuss the conditions under which each policy archetype (suppression vs. mitigation) appears to be the most appropriate.
Journal Article
Modification and de novo design of non-ribosomal peptide synthetases using specific assembly points within condensation domains
Non-ribosomal peptide synthetases (NRPSs) are giant enzyme machines that activate amino acids in an assembly line fashion. As NRPSs are not restricted to the incorporation of the 20 proteinogenic amino acids, their efficient manipulation would enable microbial production of a diverse range of peptides; however, the structural requirements for reprogramming NRPSs to facilitate the production of new peptides are not clear. Here we describe a new fusion point inside the condensation domains of NRPSs that results in the development of the exchange unit condensation domain (XUC) concept, which enables the efficient production of peptides, even containing non-natural amino acids, in yields up to 280 mg l
. This allows the generation of more specific NRPSs, reducing the number of unwanted peptide derivatives, but also the generation of peptide libraries. The XUC might therefore be suitable for the future optimization of peptide production and the identification of bioactive peptide derivatives for pharmaceutical and other applications.
Journal Article
Home and wild food procurement were associated with improved food security during the COVID-19 pandemic in two rural US states
Both food insecurity and home and wild food procurement (HWFP), including gardening, increased in many countries during the COVID-19 pandemic; yet little evidence has demonstrated what impact HWFP had on food security. Using data from a representative sample of nearly 1000 residents in the two most rural US states (Vermont and Maine) conducted via an online survey in Spring/Summer 2021, as well as matching techniques, we compare food security outcomes among households who did and did not participate in HWFP in the first year of the pandemic. Nearly 60% of respondents engaged in HWFP in some way during the first year of the pandemic, with food insecure households more likely to do HWFP. Furthermore, HWFP early in the COVID-19 pandemic is associated with improved food security in the 9-12 months later, though these improvements were primarily associated with newly, not chronically, food insecure households. Newly and chronically food insecure households were more likely to want to continue these activities in the future, but also exhibited greater barriers to land access and costs associated with these activities. These results suggest that HWFP may provide food security improvements for certain households that utilize them, especially during crisis situations. Future research about HWFP should continue to explore multiple HWFP strategies, their barriers, and their potentially myriad relationships to food security, diet, and health outcomes, especially with longitudinal data.
Journal Article
Modeling the impact of school reopening on SARS-CoV-2 transmission using contact structure data from Shanghai
Mathematical modeling studies have suggested that pre-emptive school closures alone have little overall impact on SARS-CoV-2 transmission, but reopening schools in the background of community contact reduction presents a unique scenario that has not been fully assessed.
We adapted a previously published model using contact information from Shanghai to model school reopening under various conditions. We investigated different strategies by combining the contact patterns observed between different age groups during both baseline and \"lockdown\" periods. We also tested the robustness of our strategy to the assumption of lower susceptibility to infection in children under age 15 years.
We find that reopening schools for all children would maintain a post-intervention R
< 1 up to a baseline R
of approximately 3.3 provided that daily contacts among children 10-19 years are reduced to 33% of baseline. This finding was robust to various estimates of susceptibility to infection in children relative to adults (up to 50%) and to estimates of various levels of concomitant reopening in the rest of the community (up to 40%). However, full school reopening without any degree of contact reduction in the school setting returned R
virtually back to baseline, highlighting the importance of mitigation measures.
These results, based on contact structure data from Shanghai, suggest that schools can reopen with proper precautions during conditions of extreme contact reduction and during conditions of reasonable levels of reopening in the rest of the community.
Journal Article
Social Network Effects of Nonlifesaving Early-Stage Breast Cancer Detection on Mammography Rates
We estimated the effect of anecdotes of early-stage, screen-detected cancer for which screening was not lifesaving on the demand for mammography.
We constructed an agent-based model of mammography decisions, in which 10 000 agents that represent women aged 40 to 100 years were linked together on a social network, which was parameterized with a survey of 716 women conducted through the RAND American Life Panel. Our model represents a population in equilibrium, with demographics reflecting the current US population based on the most recent available census data.
The aggregate effect of women learning about 1 category of cancers-those that would be detected but would not be lethal in the absence of screening-was a 13.8 percentage point increase in annual screening rates.
Anecdotes of detection of early-stage cancers relayed through social networks may substantially increase demand for a screening test even when the detection through screening was nonlifesaving.
Journal Article
Maximum angle of stability of a wet granular pile
Anyone who has built a sandcastle recognizes that adding liquid to the sand grains increases the overall stability. However, measurements of the stability in wet granular materials often conflict with theory and with each other. The friction-based Mohr-Coulomb model distinguishes between granular friction and interparticle friction, but uses the former without providing a physical mechanism. A frictionless model for the geometric stability of dry particles on the surface of a pile is in excellent agreement with experiment. However, the same model applied to wet grains overestimates the stability and predicts no dependence on system size. Here we take a frictionless liquid-bridge model and perform a stability analysis within the pile. We reproduce our experimentally observed dependence of the stability angle on system size, particle size and surface tension. Furthermore, we account for past discrepancies in experimental reports by showing that sidewalls can significantly increase the stability of granular material.
Journal Article
Parents’ goals for and perceptions of alphabet books
This study examined parents’ goals for reading ABC books with their children and their perceptions of page features. Factor analysis of a questionnaire answered by 225 parents of junior and senior kindergarten students revealed four goals for reading alphabet books. In order of importance as rated by parents the goals were: Learning to Read, Enjoyment and Bonding, Learning from Books, and Soothing the Child. Maternal education, number of ABC books owned, and ABC book reading frequency were related to parents’ goals. When viewing ABC pages, parents rated pages with little text, simple illustrations, and letter sound-word consistency as more appropriate for fulfilling purposes related to learning to decode than pages with a lot of text, complex illustrations, and letter sound-word violations. These perceptions are congruent with previous research and experts’ advice. However, parents rated pages with more complex illustrations as more appropriate for enjoyment, potentially putting books with complex illustrations at cross purposes with the previous goals.
Journal Article