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.

January 6 arrests and media coverage do not remobilize conservatives on social media.

Social media's pivotal role in catalyzing social movements is widely acknowledged across scientific disciplines. Past research has predominantly explored social media's ability to instigate initial mobilization while leaving the question of its capacity to sustain these movements relatively uncharted. This study investigates the persistence of movement activity on Twitter and Gab following a substantial on-the-ground mobilization event catalyzed by social media-the StoptheSteal movement culminating in the January 6th Capitol attack. Our findings indicate that the online communities active in the January 6 mobilization did not display substantial remobilization in the subsequent year. These results highlight the fact that further exploration is needed to understand the factors shaping how and when movements are sustained by social media. In this regard, our study provides valuable insights for scientists across diverse disciplines, on how certain social media platforms may contribute to the evolving dynamics of collective action.

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.

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.

Prospective randomized controlled trial of water exchange plus cap versus water exchange colonoscopy in unsedated veterans.

BACKGROUND AND AIMS: Water exchange (WE) and cap-assisted colonoscopy separately have been shown to reduce pain during insertion in unsedated patients. We hypothesized that compared with WE, WE cap-assisted colonoscopy (WECAC) could significantly lower real-time maximum insertion pain (RTMIP). METHODS: Veterans without escort were recruited, randomized, blinded, and examined at 3 U.S. Veterans Affairs sites. The primary outcome was RTMIP, defined as the highest segmental pain (0 = no pain, 10 = most severe pain) during insertion. RESULTS: Randomization (WECAC, 143; WE, 137) produced an even distribution of a racially diverse group of men and women of low socioeconomic status. The intention-to-treat analysis reported results of WECAC and WE for cecal intubation (93% and 94.2%, respectively), mean RTMIP (2.9 [standard deviation {SD}, 2.5] and 2.6 [SD, 2.4]), proportion of patients with no pain (28.7% and 27.7%), mean insertion time (18.6 minutes [SD, 15.6] and 18.8 minutes [SD, 15.9]), and overall adenoma detection rate (48.3% and 55.1%); all P values were >.05. When RTMIP was binarized as "no pain" (0) versus "some pain" (1-10) or "low pain" (0-7) versus "high pain" (8-10), different significant predictors of RTMIP were identified. CONCLUSIONS: Unsedated colonoscopy was appropriate for unescorted veterans. WE alone was sufficient. Adding a cap did not reduce RTMIP. Patient-specific factors and application of WE with insertion suction of infused water contributed to high and low RTMIP, respectively. For unescorted patients, selecting those with low anxiety, avoiding low body mass index, history of depression or self-reported poor health, and complying with the steps of WE can minimize RTMIP to ensure success of unsedated colonoscopy. (Clinical trial registration number: NCT03160859.).

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.

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™.

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.

Outcomes of screening and surveillance in people with two parents affected by colorectal cancers: experiences from the Familial Bowel Cancer Service.

BACKGROUND: The Familial Bowel Cancer Service at The Royal Melbourne Hospital was started in 1980 in order to offer bowel cancer screening services to those felt to be at a higher risk of CRC due to their family history, and upon registration in this service, patients gave consent for recording of their individual and familial medical history as pertaining to colorectal cancer in the FamBIS database. Using the FamBIS database, we sought to understand whether the subpopulation of individuals in whom both parents were diagnosed with colorectal cancer carried a higher risk of colorectal cancer or neoplastic polyps and should therefore undergo more intensive screening above that of the average-risk individual. METHODS: We conducted a single-centre retrospective cohort-study of adults (18 years of age and older) in the FamBIS database, with review of their medical histories as pertaining to CRC diagnosis, screening, and surveillance from 1980 to 2015. RESULTS: We identified and reviewed the medical histories of 96 registrants from 62 unique families. Registrants began screening as early as 24 years of age, with the mean age of first screening being at 44.6 ± 10.7 years old. The mean duration of screening was 17.3 ± 10.1 years, and through their screening period, registrants underwent an average of 11.5 ± 9.1 FOBTs and 4.4 ± 3.1 colonoscopies or sigmoidoscopies.Over the course of screening, 41 (42.7%) registrants were found to have at least one neoplasm of any kind (including adenomas, advanced adenomas, and CRC) as their first positive colonoscopic finding. In total, 12 (12.5%) of the registrants were found to have an advanced neoplasm over the course of screening and surveillance, while only 2 patients were found to be diagnosed with CRC. CONCLUSIONS: The prevalence rates for neoplasms, advanced neoplasms, and CRC in our current study were statistically significantly higher compared with those seen in average-risk populations. This supports the importance of more intensive screening for this subpopulation in preventing colorectal cancers, as well as pre-and early-cancerous neoplasms.

Worldwide Practice Patterns in Lynch Syndrome Diagnosis and Management, Based on Data From the International Mismatch Repair Consortium.

BACKGROUND & AIMS: Families with a history of Lynch syndrome often do not adhere to guidelines for genetic testing and screening. We investigated practice patterns related to Lynch syndrome worldwide, to ascertain potential targets for research and public policy efforts. METHODS: We collected data from the International Mismatch Repair Consortium (IMRC), which comprises major research and clinical groups engaged in the care of families with Lynch syndrome worldwide. IMRC institutions were invited to complete a questionnaire to characterize diagnoses of Lynch syndrome and management practice patterns. RESULTS: Fifty-five providers, representing 63 of 128 member institutions (49%) in 21 countries, completed the questionnaire. For case finding, 55% of respondents reported participating in routine widespread population tumor testing among persons with newly diagnosed Lynch syndrome-associated cancers, whereas 27% reported relying on clinical criteria with selective tumor and/or germline analyses. Most respondents (64%) reported using multigene panels for germline analysis, and only 28% reported testing tumors for biallelic mutations for cases in which suspected pathogenic mutations were not confirmed by germline analysis. Respondents reported relying on passive dissemination of information to at-risk family members, and there was variation in follow through of genetic testing recommendations. Reported risk management practices varied-nearly all programs (98%) recommended colonoscopy every 1 to 2 years, but only 35% recommended chemoprevention with aspirin. CONCLUSIONS: There is widespread heterogeneity in management practices for Lynch syndrome worldwide among IMRC member institutions. This may reflect the rapid pace of emerging technology, regional differences in resources, and the lack of definitive data for many clinical questions. Future efforts should focus on the large numbers of high-risk patients without access to state-of-the-art Lynch syndrome management.

Noninfectious immune-mediated uveitis and ocular inflammation.

Noninfectious uveitis encompasses a diverse group of ocular inflammatory disorders that share an underlying immune etiology and may be associated with systemic disease or confined primarily to the eye. Uveitis is commonly classified by anatomical location of inflammation into anterior, intermediate, posterior, and panuveitis. The treatment of noninfectious uveitis consists of corticosteroids, immunosuppressive agents, and surgically placed steroid implants. We review the epidemiology, immunopathology, and clinical features of several noninfectious immune-mediated uveitides, including HLA-B27 acute anterior uveitis, juvenile idiopathic arthritis, intermediate uveitis, sarcoidosis, Behcet's disease, Vogt-Koyanagi-Harada syndrome, sympathetic ophthalmia, and white dot syndromes. We also discuss the stepwise approach to medical treatment of immune-mediated uveitis as well as the characteristics, safety, and efficacy of immunosuppressive agents used to treat ocular inflammatory disease.

The Surgical Renaissance: Advancements in Video-Assisted Thoracoscopic Surgery and Robotic-Assisted Thoracic Surgery and Their Impact on Patient Outcomes.

Minimally invasive thoracic surgery has advanced the treatment of lung cancer since its introduction in the 1990s. Video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracic surgery (RATS) offer the advantage of smaller incisions without compromising patient outcomes. These techniques have been shown to be safe and effective in standard pulmonary resections (lobectomy and sub-lobar resection) and in complex pulmonary resections (sleeve resection and pneumonectomy). Furthermore, several studies show these techniques enhance patient outcomes from early recovery to improved quality of life (QoL) and excellent oncologic results. The rise of RATS has yielded further operative benefits compared to thoracoscopic surgery. The wristed instruments, neutralization of tremor, dexterity, and magnification allow for more precise and delicate dissection of tissues and vessels. This review summarizes of the advancements in minimally invasive thoracic surgery and the positive impact on patient outcomes.

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.

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.

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.

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.

Adherence to Recommendations for Repeat Surveillance After Publication of New Postpolypectomy Guidelines.

Background and Aims: The 2012 and 2020 US Multi-Society Task Force postpolypectomy guidelines have recommended progressively longer surveillance intervals for patients with low-risk adenomas (LRAs). These guidelines require data from past colonoscopies. We examined the impact of the 2012 guidelines for second surveillance on clinical practice, including the availability of prior colonoscopy data, with the aim of informing the implementation of the 2020 guidelines. Methods: We identified surveillance colonoscopies at Stanford Health Care and the Palo Alto Veterans Affairs Health Care System in 3 periods: preguideline (March-August 2012), postguideline (January-June 2013), and delayed postguideline (July-September 2017). We collected data on the most recent previous colonoscopy, findings at the study entry surveillance colonoscopy, and recommendations for subsequent surveillance. Results: Among 977 patients, the most recent prior colonoscopy data were available in 78% of preguideline, 78% of postguideline, and 61% of delayed postguideline cases (P < .001). The fraction of surveillance colonoscopy reports that deferred recommendations awaiting pathology increased from 6% to 11% in preguideline and postguideline to 59% in delayed postguideline cases (P < .001). Overall adherence to guidelines for subsequent surveillance was similar in all 3 periods (54%-67%; P = .089). In the postguideline and delayed postguideline periods combined, a 10-year subsequent surveillance interval was recommended in 0 of 29 cases with LRA followed by normal surveillance colonoscopy. Conclusion: In patients undergoing surveillance, prior colonoscopy data were not always available and recommendations were often deferred awaiting pathology. Adherence to subsequent surveillance guidelines was suboptimal, especially for LRA followed by normal colonoscopy. Strategies addressing these gaps are needed to optimize implementation of the updated 2020 postpolypectomy guidelines.

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.