The effects of Facebook and Instagram on the 2020 election: A deactivation experiment.

We study the effect of Facebook and Instagram access on political beliefs, attitudes, and behavior by randomizing a subset of 19,857 Facebook users and 15,585 Instagram users to deactivate their accounts for 6 wk before the 2020 U.S. election. We report four key findings. First, both Facebook and Instagram deactivation reduced an index of political participation (driven mainly by reduced participation online). Second, Facebook deactivation had no significant effect on an index of knowledge, but secondary analyses suggest that it reduced knowledge of general news while possibly also decreasing belief in misinformation circulating online. Third, Facebook deactivation may have reduced self-reported net votes for Trump, though this effect does not meet our preregistered significance threshold. Finally, the effects of both Facebook and Instagram deactivation on affective and issue polarization, perceived legitimacy of the election, candidate favorability, and voter turnout were all precisely estimated and close to zero.

Buckling forces and the wavy folds between pleural epithelial cells.

Cell shapes in tissues are affected by the biophysical interaction between cells. Tissue forces can influence specific cell features such as cell geometry and cell surface area. Here, we examined the 2-dimensional shape, size, and perimeter of pleural epithelial cells at various lung volumes. We demonstrated a 1.53-fold increase in 2-dimensional cell surface area and a 1.43-fold increase in cell perimeter at total lung capacity compared to residual lung volume. Consistent with previous results, close inspection of the pleura demonstrated wavy folds between pleural epithelial cells at all lung volumes. To investigate a potential explanation for the wavy folds, we developed a physical simulacrum suggested by D'Arcy Thompson in On Growth and Form. The simulacrum suggested that the wavy folds were the result of redundant cell membranes unable to contract. To test this hypothesis, we developed a numerical simulation to evaluate the impact of an increase in 2-dimensional cell surface area and cell perimeter on the shape of the cell-cell interface. Our simulation demonstrated that an increase in cell perimeter, rather than an increase in 2-dimensional cell surface area, had the most direct impact on the presence of wavy folds. We conclude that wavy folds between pleural epithelial cells reflects buckling forces arising from the excess cell perimeter necessary to accommodate visceral organ expansion.

Evolving topological order in the postnatal visceral pleura.

BACKGROUND: Changes in epithelial cell shape reflects optimal cell packing and the minimization of surface free energy, but also cell-cell interactions, cell proliferation, and cytoskeletal rearrangements. RESULTS: Here, we studied the structure of the rat pleura in the first 15 days after birth. After pleural isolation and image segmentation, the analysis demonstrated a progression of epithelial order from postnatal day 1 (P1) to P15. The cells with the largest surface area and greatest shape variability were observed at P1. In contrast, the cells with the smallest surface area and most shape consistency were observed at P15. A comparison of polygonal cell geometries demonstrated progressive optimization with an increase in the number of hexagons (six-sided) as well as five-sided and seven-sided polygons. Analysis of the epithelial organization with Voronoi tessellations and graphlet motif frequencies demonstrated a developmental path strikingly distinct from mathematical and natural reference paths. Graph Theory analysis of cell connectivity demonstrated a progressive decrease in network heterogeneity and clustering coefficient from P1 to P15. CONCLUSIONS: We conclude that the rat pleura undergoes a striking change in pleural structure from P1 to P15. Further, a geometric and network-based approach can provide a quantitative characterization of these developmental changes.

Preoperative Workup of Patients With Excessive Central Airway Collapse: Does Stent Evaluation Serve a Role?

BACKGROUND: Tracheobronchoplasty (TBP) is a definitive anatomic intervention for patients with severe symptomatic expiratory central airway collapse. Although stent evaluations have been described for surgical workup, current literature does not address if improvement during stent evaluation is sustained after TBP. We compared health-related quality of life (HRQOL) and functional status responses after airway stenting to those post-TBP. METHODS: A retrospective review was performed in patients with severe expiratory central airway collapse who underwent stent evaluation followed by TBP from January 2004 to December 2019. Baseline, poststent, 3- and 12-month postoperative HRQOL scores, and functional status were analyzed with statistical tests as appropriate. RESULTS: One hundred twenty patients underwent a stent evaluation and TBP. Baseline and stent evaluation measurements were compared with statistically and clinically significant differences in the Cough Quality-of-life Questionnaire (CQLQ) (55 vs. 68, P <0.01), Modified Medical Research Council (mMRC) 0 to 2 (90% vs. 47%, P <0.01), 6-minute walk test (6MWT) (1301 ft vs. 1138 ft, P <0.01). Improvements in the HRQOL and functional status were maintained from stent evaluation to 3 months postoperatively [CQLQ 55 vs. 54, P =0.63; mMRC 0 to 2 (87% vs. 84%), P =0.39; 6MWT 1350 ft vs. 1314 ft, P =0.33], and 12 months postoperatively [CQLQ 54 vs. 54, P =0.91; mMRC 0 to 2 (95% vs. 86%), P =0.74; 6MWT 1409 ft vs. 1328 ft, P =0.13]. The magnitude of change between the data was not significantly different between the stent evaluation, 3-, and 12 months postoperative. Predicted forced expiratory volume in 1-second measurements at baseline, after stent placement, 3 months, and 12 months post-TBP were 74%, 79%, 73%, and 73%, respectively, and not clinically significant. CONCLUSIONS: Improvement after stent evaluation and the magnitude of improvement may be predictive of postoperative outcomes up to 1 year after surgery.

Partisan conflict over content moderation is more than disagreement about facts.

Social media companies have come under increasing pressure to remove misinformation from their platforms, but partisan disagreements over what should be removed have stymied efforts to deal with misinformation in the United States. Current explanations for these disagreements center on the "fact gap"-differences in perceptions about what is misinformation. We argue that partisan differences could also be due to "party promotion"-a desire to leave misinformation online that promotes one's own party-or a "preference gap"-differences in internalized preferences about whether misinformation should be removed. Through an experiment where respondents are shown false headlines aligned with their own or the opposing party, we find some evidence of party promotion among Democrats and strong evidence of a preference gap between Democrats and Republicans. Even when Republicans agree that content is false, they are half as likely as Democrats to say that the content should be removed and more than twice as likely to consider removal as censorship.

Like-minded sources on Facebook are prevalent but not polarizing.

Many critics raise concerns about the prevalence of 'echo chambers' on social media and their potential role in increasing political polarization. However, the lack of available data and the challenges of conducting large-scale field experiments have made it difficult to assess the scope of the problem1,2. Here we present data from 2020 for the entire population of active adult Facebook users in the USA showing that content from 'like-minded' sources constitutes the majority of what people see on the platform, although political information and news represent only a small fraction of these exposures. To evaluate a potential response to concerns about the effects of echo chambers, we conducted a multi-wave field experiment on Facebook among 23,377 users for whom we reduced exposure to content from like-minded sources during the 2020 US presidential election by about one-third. We found that the intervention increased their exposure to content from cross-cutting sources and decreased exposure to uncivil language, but had no measurable effects on eight preregistered attitudinal measures such as affective polarization, ideological extremity, candidate evaluations and belief in false claims. These precisely estimated results suggest that although exposure to content from like-minded sources on social media is common, reducing its prevalence during the 2020 US presidential election did not correspondingly reduce polarization in beliefs or attitudes.

How do social media feed algorithms affect attitudes and behavior in an election campaign?

We investigated the effects of Facebook's and Instagram's feed algorithms during the 2020 US election. We assigned a sample of consenting users to reverse-chronologically-ordered feeds instead of the default algorithms. Moving users out of algorithmic feeds substantially decreased the time they spent on the platforms and their activity. The chronological feed also affected exposure to content: The amount of political and untrustworthy content they saw increased on both platforms, the amount of content classified as uncivil or containing slur words they saw decreased on Facebook, and the amount of content from moderate friends and sources with ideologically mixed audiences they saw increased on Facebook. Despite these substantial changes in users' on-platform experience, the chronological feed did not significantly alter levels of issue polarization, affective polarization, political knowledge, or other key attitudes during the 3-month study period.

Asymmetric ideological segregation in exposure to political news on Facebook.

Does Facebook enable ideological segregation in political news consumption? We analyzed exposure to news during the US 2020 election using aggregated data for 208 million US Facebook users. We compared the inventory of all political news that users could have seen in their feeds with the information that they saw (after algorithmic curation) and the information with which they engaged. We show that (i) ideological segregation is high and increases as we shift from potential exposure to actual exposure to engagement; (ii) there is an asymmetry between conservative and liberal audiences, with a substantial corner of the news ecosystem consumed exclusively by conservatives; and (iii) most misinformation, as identified by Meta's Third-Party Fact-Checking Program, exists within this homogeneously conservative corner, which has no equivalent on the liberal side. Sources favored by conservative audiences were more prevalent on Facebook's news ecosystem than those favored by liberals.

Reshares on social media amplify political news but do not detectably affect beliefs or opinions.

We studied the effects of exposure to reshared content on Facebook during the 2020 US election by assigning a random set of consenting, US-based users to feeds that did not contain any reshares over a 3-month period. We find that removing reshared content substantially decreases the amount of political news, including content from untrustworthy sources, to which users are exposed; decreases overall clicks and reactions; and reduces partisan news clicks. Further, we observe that removing reshared content produces clear decreases in news knowledge within the sample, although there is some uncertainty about how this would generalize to all users. Contrary to expectations, the treatment does not significantly affect political polarization or any measure of individual-level political attitudes.

Facilitated Transport across Glycocalyceal Barriers in the Chick Chorioallantoic Membrane.

Targeted drug delivery to visceral organs offers the possibility of not only limiting the required dose, but also minimizing drug toxicity; however, there is no reliable method for delivering drugs to the surface of visceral organs. Here, we used six color tracers and the chick chorioallantoic membrane (CAM) model to investigate the use of the heteropolysaccharide pectin to facilitate tracer diffusion across the glycocalyceal charge barrier. The color tracers included brilliant blue, Congo red, crystal violet, indocyanine green, methylene blue, and methyl green. The direct application of the tracers to the CAM surface or embedding tracers into linear-chain nanocellulose fiber films resulted in no significant diffusion into the CAM. In contrast, when the tracers were actively loaded into branched-chain pectin films, there was significant detectable diffusion of the tracers into the CAM. The facilitated diffusion was observed in the three cationic tracers but was limited in the three anionic tracers. Diffusion appeared to be dependent on ionic charge, but independent of tracer size or molecular mass. We conclude that dye-loaded pectin films facilitated the diffusion of color tracers across the glycocalyceal charge barrier and may provide a therapeutic path for drug delivery to the surface of visceral organs.

Randomized controlled trial investigating use of submucosal injection of EverLift™ in rates of complete resection of non-pedunculated 4-9 mm polyps.

INTRODUCTION: Currently, cold snare polypectomy (CSP) without submucosal injection is recommended for removing polyps < 10 mm. Use of viscous submucosal agents has not been previously evaluated in CSP. We investigate the potential role of EverLift™ (GI Supply, Pennsylvania) in CSP. METHODS: The study is a single-center prospective randomized non-inferiority clinical trial evaluating CSP of non-pedunculated 4-9 mm polyps, with or without submucosal injection of EverLift™. Patients 18-80 years of age presenting for colonoscopy were recruited. Eligible polyps underwent block randomization to CSP with or without EverLift™. Following CSP, two biopsies were performed at the CSP site margin. The primary non-inferiority outcome was complete resection rate, defined by absence of residual polyp in the margin biopsies (non-inferiority margin -10%). RESULTS: A total of 291 eligible polyps underwent CSP, with 142 removed using EverLift™. There was similar polyp size and distribution of pathology between the two groups. Overall, there was a low rate of positive margins with (1.4%) or without submucosal injection (2.8%), with no significant difference in complete resection (difference 1.28%, 95% CI: -2.66 to 5.42%), demonstrating non-inferiority of EverLift™ injection. Use of EverLift™ significantly increased CSP time (109.8 vs 38.8 s, p < 0.0001) and frequency of use of hemostatic clips (13.4 vs 3.6%, p = 0.002). CONCLUSION: Submucosal injection of EverLift™ was non-inferior to CSP of 4-9 mm polyps without injection and increased time for resection as well as use of hemostatic clips to control acute bleeding. Our results suggest that polypectomy of 4-9 mm polyps can be safely performed without submucosal injection of EverLift™.

Randomized Controlled Trial Investigating Cold Snare and Forceps Polypectomy Among Small POLYPs in Rates of Complete Resection: The TINYPOLYP Trial.

INTRODUCTION: Optimizing complete resection during colonoscopy is important because residual neoplastic tissue may play a role in interval cancers. The US Multi-Society Task Force recommends diminutive (≤5 mm) and small (6-9 mm) polyps be removed by cold snare polypectomy (CSP). However, evidence is less clear whether CSP retains significant advantage over cold forceps polypectomy (CFP) for polyps ≤3 mm. METHODS: This study is a single-center prospective noninferiority randomized clinical trial evaluating CFP and CSP for nonpedunculated polyps ≤3 mm. Patients 18 years and older undergoing colonoscopy for any indication were recruited. During each colonoscopy, polyps underwent block randomization to removal with CFP or CSP. After polypectomy, 2 biopsies were taken from the polypectomy margin. The primary noninferiority outcome was the complete resection rate, defined by absence of residual polyp in the margin biopsies. RESULTS: A total of 179 patients were included. Patients had similar distribution in age, sex, race/ethnicity, as well as indication of procedure. A total of 279 polyps ≤3 mm were identified, with 138 in the CSP group and 141 in the CFP group. Mean polypectomy time was longer for CSP compared with CFP (42.3 vs 23.2 seconds, P < 0.001), although a higher proportion of polyps removed by CFP were removed in more than 1 piece compared with CSP (15.6 vs 3.6%, P < 0.001). There were positive margin biopsies in 2 cases per cohort, with a complete resection rate of 98.3% in both groups. There was no significant difference in cohorts in complete resection rates (difference in complete resection rates was 0.057%, 95% confidence interval: -4.30% to 4.53%), demonstrating noninferiority of CFP compared with CSP. DISCUSSION: Use of CFP was noninferior to CSP in the complete resection of nonpedunculated polyps ≤3 mm. CSP required significantly more time to perform compared with CFP. CFP should be considered an acceptable alternative to CSP for removal of polyps ≤3 mm.

The digital repression of social movements, protest, and activism: A synthetic review.

Repression research examines the causes and consequences of actions or policies that are meant to, or actually do, raise the costs of activism, protest, and/or social movement activity. The rise of digital and social media has brought substantial increases in attention to the repression of digital activists and movements and/or to the use of digital tools in repression, which is spread across many disciplines and areas of study. We organize and review this growing welter of research under the concept of digital repression by expanding a typology that distinguishes actions based on actor type, whether actions are overt or covert, and whether behaviors are shaped by coercion or channeling. This delineation between broadly different forms of digital repression allows researchers to develop expectations about digital repression, better understand what is "new" about digital repression in terms of explanatory factors, and better understand the consequences of digital repression.

Loosening the belt on magnetic sphincter augmentation indications: does body mass index matter?

BACKGROUND: Magnetic sphincter augmentation (MSA) is an effective treatment for gastroesophageal reflux disease (GERD). However, the impact of obesity on MSA outcomes is unknown. The objective of this study was to evaluate the effectiveness of MSA in patients with GERD and obesity. METHODS: A retrospective cohort study was performed of consecutive patients who underwent laparoscopic MSA at three high-volume centers from 2016 to 2019. Patients were grouped into four cohorts according to the World Health Organization body mass index (BMI) classification: BMI < 25 (normal weight), BMI 25-29.9 (overweight), BMI 30-34.9 (obese class I), and BMI > 35 (obese class II-III). Preoperative, operative, and postoperative data were compared between groups. RESULTS: A total of 621 patients underwent laparoscopic MSA during the study period. Follow-up with endoscopy or video esophagram was available for 361 patients (58%) with a median follow-up of 15.4 months. Baseline characteristics of the groups were similar except the BMI > 35 group had more females and a higher preoperative median DeMeester score. There were no significant differences in outcomes between normal weight, overweight, and obese patient groups undergoing MSA. All groups experienced significant reductions in acid suppressive medication use, low GERD-HRQL scores, low DeMeester scores, few intraoperative and postoperative complications, and low rates of hiatal hernia recurrence after MSA. CONCLUSIONS: Magnetic sphincter augmentation is safe and effective in improving GERD symptoms, reducing esophageal acid exposure, and preventing hiatal hernia recurrence, irrespective of patient BMI. MSA should be considered an acceptable treatment option for obese patients with GERD.

Screenomics: A Framework to Capture and Analyze Personal Life Experiences and the Ways that Technology Shapes Them.

Digital experiences capture an increasingly large part of life, making them a preferred, if not required, method to describe and theorize about human behavior. Digital media also shape behavior by enabling people to switch between different content easily, and create unique threads of experiences that pass quickly through numerous information categories. Current methods of recording digital experiences provide only partial reconstructions of digital lives that weave - often within seconds - among multiple applications, locations, functions and media. We describe an end-to-end system for capturing and analyzing the "screenome" of life in media, i.e., the record of individual experiences represented as a sequence of screens that people view and interact with over time. The system includes software that collects screenshots, extracts text and images, and allows searching of a screenshot database. We discuss how the system can be used to elaborate current theories about psychological processing of technology, and suggest new theoretical questions that are enabled by multiple time scale analyses. Capabilities of the system are highlighted with eight research examples that analyze screens from adults who have generated data within the system. We end with a discussion of future uses, limitations, theory and privacy.

Predictive factors for adenoma detection rates: a video study of endoscopist practices.

Background and study aims In 2015, the American Society for Gastrointestinal Endoscopy (ASGE) and American College of Gastroenterology (ACG) Task Force on Quality in Endoscopy deemed adenoma detection rate (ADR) the most important quality measure for colonoscopy. There has been much interest in factors that can increase ADR. To date, however, few studies have looked at what intra-procedural endoscopist practices are associated with improving ADR. We conducted a retrospective review of colonoscopy videos to evaluate intra-procedural practices that could be associated with ADR. Methods Videos were recorded of colonoscopies performed between September and December 2017 at the Palo Alto Veterans Affairs Health Care System. Colonoscopies for screening and surveillance were included for video review. Factors assessed included withdrawal time, intra-procedural cleaning, inspection technique, and other variables (colon distention, removal of equivocal/hyperplastic polyps). A series of multiple regression analyses was conducted on variables of interest before running a final model of significant predictors. Results A total of 130 videos were reviewed from nine endoscopists whose ADRs ranged between 37.5 % and 73.7 %. The final regression model was significant (F = 15.35, df = 2, P  = 0.0044), R 2  = 0.8365) with close inspection of behind folds and quality of cecal inspection being the factors highly correlated with predicting ADR. Withdrawal and inspection times, colonic wall distention, removal of equivocal/hyperplastic polyps, quality of rectal inspection, suctioning, and washing were factors moderately correlated with predicting ADR. Conclusions We found that behind-fold inspection and a meticulous cecal inspection technique were predictive of a high ADR.

Coronavirus Disease 2019 (COVID-19): A Modeling Study of Factors Driving Variation in Case Fatality Rate by Country.

Background: The novel Severe Acute Respiratory Syndrome Coronavirus-2 has led to a global pandemic in which case fatality rate (CFR) has varied from country to country. This study aims to identify factors that may explain the variation in CFR across countries. Methods: We identified 24 potential risk factors affecting CFR. For all countries with over 5000 reported COVID-19 cases, we used country-specific datasets from the WHO, the OECD, and the United Nations to quantify each of these factors. We examined univariable relationships of each variable with CFR, as well as correlations among predictors and potential interaction terms. Our final multivariable negative binomial model included univariable predictors of significance and all significant interaction terms. Results: Across the 39 countries under consideration, our model shows COVID-19 case fatality rate was best predicted by time to implementation of social distancing measures, hospital beds per 1000 individuals, percent population over 70 years, CT scanners per 1 million individuals, and (in countries with high population density) smoking prevalence. Conclusion: Our model predicted an increased CFR for countries that waited over 14 days to implement social distancing interventions after the 100th reported case. Smoking prevalence and percentage population over the age of 70 years were also associated with higher CFR. Hospital beds per 1000 and CT scanners per million were identified as possible protective factors associated with decreased CFR.

Thalidomide Use Reduces Risk of Refractory Gastrointestinal Bleeding in Patients with Continuous Flow Left Ventricular Assist Devices.

Gastrointestinal (GI) bleeding is a common complication seen in patients with implanted continuous flow left ventricular assist devices (CF-LVAD), often attributed to arteriovenous malformations (AVMs). Whether thalidomide reduces recurrent GI bleeding risk in CF-LVAD patients has been incompletely evaluated. We conducted a retrospective review of all CF-LVAD patients at our institution with GI bleeding from AVMs who had a trial both off and on thalidomide. The primary endpoint was time to rebleed, while secondary endpoints included overall GI bleeding events, packed red blood cell (PRBC) transfusion requirements, and adverse events related to thalidomide. We report on 24 patients with recurrent AVM-associated GI bleeding who met criteria for and received thalidomide therapy, of which 17 had sufficient follow-up to be ultimately included for final analysis. We found the risk of rebleeding was significantly reduced in those on thalidomide therapy versus off (hazard ratio = 0.23, p = 0.022). The median number of GI bleeds per year was reduced from 4.6 to 0.4 (p = 0.0008) and the PRBC requirement was lower (36.1 vs. 0.9 units per year, p = 0.004) in those on thalidomide therapy. The adverse event rate with thalidomide was 59%, with symptoms resolution in most following dose reduction without increased bleeding. Thalidomide reduced the risk of AVM-associated GI rebleeding, number of bleeding events, and PRBC requirements in CF-LVAD patients. When initiating therapy, potential side effects and overall clinical context should be considered.