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Content on Twitter’s home timeline is selected and ordered by personalization algorithms. By consistently ranking certain content higher, these algorithms may amplify some messages while reducing the visibility of others. There’s been intense public and scholarly debate about the possibility that some political groups benefit more from algorithmic amplification than others. We provide quantitative evidence from a long-running, massive-scale randomized experiment on the Twitter platform that committed a randomized control group including nearly 2 million daily active accounts to a reverse-chronological content feed free of algorithmic personalization. We present two sets of findings. First, we studied tweets by elected legislators from major political parties in seven countries. Our results reveal a remarkably consistent trend: In six out of seven countries studied, the mainstream political right enjoys higher algorithmic amplification than the mainstream political left. Consistent with this overall trend, our second set of findings studying the US media landscape revealed that algorithmic amplification favors right-leaning news sources. We further looked at whether algorithms amplify far-left and far-right political groups more than moderate ones; contrary to prevailing public belief, we did not find evidence to support this hypothesis. We hope our findings will contribute to an evidence-based debate on the role personalization algorithms play in shaping political content consumption.

The association of irregular sleep schedules with circadian timing and academic performance has not been systematically examined. We studied 61 undergraduates for 30 days using sleep diaries, and quantified sleep regularity using a novel metric, the sleep regularity index (SRI). In the most and least regular quintiles, circadian phase and light exposure were assessed using salivary dim-light melatonin onset (DLMO) and wrist-worn photometry, respectively. DLMO occurred later (00:08 ± 1:54 vs. 21:32 ± 1:48; p < 0.003); the daily sleep propensity rhythm peaked later (06:33 ± 0:19 vs. 04:45 ± 0:11; p < 0.005); and light rhythms had lower amplitude (102 ± 19 lux vs. 179 ± 29 lux; p < 0.005) in Irregular compared to Regular sleepers. A mathematical model of the circadian pacemaker and its response to light was used to demonstrate that Irregular vs. Regular group differences in circadian timing were likely primarily due to their different patterns of light exposure. A positive correlation (r = 0.37; p < 0.004) between academic performance and SRI was observed. These findings show that irregular sleep and light exposure patterns in college students are associated with delayed circadian rhythms and lower academic performance. Moreover, the modeling results reveal that light-based interventions may be therapeutically effective in improving sleep regularity in this population.

Abstract Study Objectives To examine whether drivers are aware of sleepiness and associated symptoms, and how subjective reports predict driving impairment and physiological drowsiness. Methods Sixteen shift workers (19–65 years; 9 women) drove an instrumented vehicle for 2 hours on a closed-loop track after a night of sleep and a night of work. Subjective sleepiness/symptoms were rated every 15 minutes. Severe and moderate driving impairment was defined by emergency brake maneuvers and lane deviations, respectively. Physiological drowsiness was defined by eye closures (Johns drowsiness scores) and EEG-based microsleep events. Results All subjective ratings increased post night-shift (p < 0.001). No severe drive events occurred without noticeable symptoms beforehand. All subjective sleepiness ratings, and specific symptoms, predicted a severe (emergency brake) driving event occurring in the next 15 minutes (OR: 1.76–2.4, AUC > 0.81, p < 0.009), except “head dropping down”. Karolinska Sleepiness Scale (KSS), ocular symptoms, difficulty keeping to center of the road, and nodding off to sleep, were associated with a lane deviation in the next 15 minutes (OR: 1.17–1.24, p<0.029), although accuracy was only “fair” (AUC 0.59–0.65). All sleepiness ratings predicted severe ocular-based drowsiness (OR: 1.30–2.81, p < 0.001), with very good-to-excellent accuracy (AUC > 0.8), while moderate ocular-based drowsiness was predicted with fair-to-good accuracy (AUC > 0.62). KSS, likelihood of falling asleep, ocular symptoms, and “nodding off” predicted microsleep events, with fair-to-good accuracy (AUC 0.65–0.73). Conclusions Drivers are aware of sleepiness, and many self-reported sleepiness symptoms predicted subsequent driving impairment/physiological drowsiness. Drivers should self-assess a wide range of sleepiness symptoms and stop driving when these occur to reduce the escalating risk of road crashes due to drowsiness. Graphical Abstract

Night-shift workers are at high risk of drowsiness-related motor vehicle crashes as a result of circadian disruption and sleep restriction. However, the impact of actual night-shift work on measures of drowsiness and driving performance while operating a real motor vehicle remains unknown. Sixteen night-shift workers completed two 2-h daytime driving sessions on a closed driving track at the Liberty Mutual Research Institute for Safety: (i) a postsleep baseline driving session after an average of 7.6 ± 2.4 h sleep the previous night with no night-shift work, and (ii) a postnight-shift driving session following night-shift work. Physiological measures of drowsiness were collected, including infrared reflectance oculography, electroencephalography, and electrooculography. Driving performance measures included lane excursions, near-crash events, and drives terminated because of failure to maintain control of the vehicle. Eleven near-crashes occurred in 6 of 16 postnight-shift drives (37.5%), and 7 of 16 postnight-shift drives (43.8%) were terminated early for safety reasons, compared with zero near-crashes or early drive terminations during 16 postsleep drives (Fishers exact: P = 0.0088 and P = 0.0034, respectively). Participants had a significantly higher rate of lane excursions, average Johns Drowsiness Scale, blink duration, and number of slow eye movements during postnight-shift drives compared with postsleep drives (3.09/min vs. 1.49/min; 1.71 vs. 0.97; 125 ms vs. 100 ms; 35.8 vs. 19.1; respectively, P < 0.05 for all). Night-shift work increases driver drowsiness, degrading driving performance and increasing the risk of near-crash drive events. With more than 9.5 million Americans working overnight or rotating shifts and one-third of United States commutes exceeding 30 min, these results have implications for traffic and occupational safety.

In a cluster-randomized trial involving resident physicians working in pediatric ICUs, resident physicians were randomly assigned to schedules that included shifts of 24 hours or more or to schedules with shifts of 16 hours or less. Contrary to the authors’ hypothesis, resident physicians made fewer serious medical errors when they followed the extended schedule.

The Carolingians did nor think that the Franks were the chosen people or had replaced Old Testament Israel at least not in any straightforward sense. They were not alone in that. Although within the limits of this article I have not been able to survey all the relevant evidence, when one sets comparable material from elsewhere in the early medieval West alongside Carolingian texts, similar patterns emerge. The prologue to Alfred the Great's Law Code, for example, begins with the Law of Moses but historicizes it in a similar fashion to how the emperor's speech in Ermoldus's \"In Praise of Louis\" puts Christian distance between the Franks and Israel. For Alfred, Mosaic Law was the starting point of a tradition of legislative activity, which extended, with the coming of Christ, to the apostles providing rules for gentile converts and then to the receipt of Christianity by many peoples (the English among them) who established divinely inspired laws through the holding of synods.95 Alfred's laws claimed authority from participation within this universal process, not from any ideology of the English as \"a new Chosen People\" succeeding Israel. A common framework underlay how early medieval writers utilized ideas of chosenness or identification with Israel, and it was not one that supported the \"idea that God might single out a distinct culture for His special favour.\"97 If historians continue to use the language of chosen peoples and New Israels, they run the risk of misleading their readers about the degree to which claims to exclusive election or divine favor were made by the elite of early medieval ethnic groups. Some scholars have already begun the process of trying to nuance this problematic language, but it must be asked whether it serves any useful purpose at all.98 We need to speak more clearly about the function that references to election and to Israel served in early medieval texts.

A wealth of political writings survives from early Christian Ireland. While traditionally this material has been understood in terms of a dichotomy between \"pagan\" and \"Christian,\" recent scholarship has borrowed the category of the \"secular\" from late antique studies to make sense of early Irish intellectual culture and its political discourses. This article builds on this trend to reveal, through close examination of seventh-century Irish writings, a multitude of differently Christianized discourses existing simultaneously, sometimes even within a single text. Just as the boundary between the \"pagan\" and the \"secular\" was not fixed, so too the boundary between the \"Christian\" and the \"secular,\" giving rise to many different ways late antique Christians (in Ireland and elsewhere) could speak about politics. Much late antique scholarship on the \"secular\" assumes it was a passing phase ending in Christianization, but this research argues that \"secularity\" retained its importance in societies where Christians constantly debated and disagreed over where the boundaries of the \"Christian\" lay.

Abstract Study Objectives: Firefighters’ schedules include extended shifts and long work weeks which cause sleep deficiency and circadian rhythm disruption. Many firefighters also suffer from undiagnosed sleep disorders, exacerbating fatigue. We tested the hypothesis that a workplace-based Sleep Health Program (SHP) incorporating sleep health education and sleep disorders screening would improve firefighter health and safety compared to standard practice. Design: Prospective station-level randomized, field-based intervention. Setting: US fire department. Participants: 1189 firefighters. Interventions: Sleep health education, questionnaire-based sleep disorders screening, and sleep clinic referrals for respondents who screened positive for a sleep disorder. Measurements and Results: Firefighters were randomized by station. Using departmental records, in an intention-to-treat analysis, firefighters assigned to intervention stations which participated in education sessions and had the opportunity to complete sleep disorders screening reported 46% fewer disability days than those assigned to control stations (1.4 ± 5.9 vs. 2.6 ± 8.5 days/firefighter, respectively; p = .003). There were no significant differences in departmental injury or motor vehicle crash rates between the groups. In post hoc analysis accounting for intervention exposure, firefighters who attended education sessions were 24% less likely to file at least one injury report during the study than those who did not attend, regardless of randomization (OR [95% CI] 0.76 [0.60, 0.98]; χ2 = 4.56; p = .033). There were no significant changes pre- versus post-study in self-reported sleep or sleepiness in those who participated in the intervention. Conclusions: A firefighter workplace-based SHP providing sleep health education and sleep disorders screening opportunity can reduce injuries and work loss due to disability in firefighters.