Algorithmic amplification of politics on Twitter

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.

Political content is a major part of the public conversation on Twitter. Politicians, political organizations, and news outlets engage large audiences on Twitter. At the same time, Twitter employs algorithms that learn from data to sort content on the platform. This interplay of algorithmic content curation and political discourse has been the subject of intense scholarly debate and public scrutiny (1–15). When first established as a service, Twitter used to present individuals with content from accounts they followed, arranged in a reverse chronological feed. In 2016, Twitter introduced machine learning algorithms to render tweets on this feed called Home timeline based on a personalized relevance model (16). Individuals would now see older tweets deemed relevant to them, as well as some tweets from accounts they did not directly follow.Personalized ranking prioritizes some tweets over others on the basis of content features, social connectivity, and user activity. There is evidence that different political groups use Twitter differently to achieve political goals (17–20). What has remained a matter of debate, however, is whether or not any ranking advantage falls along established political contours, such as the left or right (2, 7), the center or the extremes (1, 3), specific parties (2, 7), or news sources of a certain political inclination (21). In this work, we provide systematic quantitative insights into this question based on a massive-scale randomized experiment on the Twitter platform.     

新媒体时代的艾滋病预防与倡导

如何提高人们对艾滋病的认知和减少歧视？在众多的教育渠道中,诸如通过学校、工作场所、职业介绍中心、健康服务中心进行教育等,已大大提高了公众预防艾滋病的意识。其中,大众传媒在推进艾滋病教育工作中发挥了极其重要的作用。当前,新媒体技术的不断涌现,为艾滋病相关知识的传播提供了更多有益的手段和可行的方法。有哪些新媒体技术被纳入了艾滋病防治工作？在抗击艾滋病的项目中,如何采取恰当的新媒体策略？文章对以往艾滋病预防和宣传活动中所运用的新媒体技术进行了回顾和总结,从而帮助决策者和社会各界了解新媒体的使用方法和优势,将其更好地运用到实践中。     

A cross-hazard analysis of terse message retransmission on Twitter

For decades, public warning messages have been relayed via broadcast information channels, including radio and television; more recently, risk communication channels have expanded to include social media sites, where messages can be easily amplified by user retransmission. This research examines the factors that predict the extent of retransmission for official hazard communications disseminated via Twitter. Using data from events involving five different hazards, we identity three types of attributes—local network properties, message content, and message style—that jointly amplify and/or attenuate the retransmission of official communications under imminent threat. We find that the use of an agreed-upon hashtag and the number of users following an official account positively influence message retransmission, as does message content describing hazard impacts or emphasizing cohesion among users. By contrast, messages directed at individuals, expressing gratitude, or including a URL were less widely disseminated than similar messages without these features. Our findings suggest that some measures commonly taken to convey additional information to the public (e.g., URL inclusion) may come at a cost in terms of message amplification; on the other hand, some types of content not traditionally emphasized in guidance on hazard communication may enhance retransmission rates.Under conditions of imminent threat, rapid communication of warning information to the public is a primary strategy for decreasing loss of life and increasing public safety by eliciting protective actions from those at risk (1). For decades, public warnings have been relayed via mass media channels, including radio, broadcast television, and sirens (2). With the advent of social computing, warnings have begun to be disseminated via online social networks (OSNs), where messages can be more easily propagated and amplified by the user population (3–6). Risk amplification via message retransmission in this setting is important because it enables a message to reach individuals beyond the sender’s direct contacts, increasing exposure and potentially leading to lifesaving actions (7). Although such transmission occurs offline as well (8–11), OSNs offer the potential for the rapid retransmission of short messages with higher fidelity—and to more persons—than would typically be feasible via other means.In addition to enabling message diffusion, the clustered structure of most OSNs (12, 13) allows retransmission to expose individuals to the same message multiple times. Multiple exposures to messages have been linked to greater confidence in message veracity (14, 15), which can lead to further sharing (16, 17). Repeated exposures from multiple network ties are often a prerequisite for the spread of information through networks, and are of particular importance for inducing behavioral change (4, 18–20). Under conditions of imminent threat, exposure to a warning message from a trusted source (such as a neighbor, friend, or family member) strongly affects one’s willingness to take protective actions (21, 22). This highlights the need to understand the factors that enhance or suppress the amplification of emergent risk messages within OSNs, with particular attention on the features of the messages themselves. Such an understanding can inform evidence-based strategies to increase message proliferation, thus allowing risk communicators to achieve a higher level of message penetration and/or to increase the number of exposures per person in the impacted population. This research examines message retransmission—commonly referred to as “retweeting”—on Twitter, identifying network, content, and style features that promote the amplification (23) of terse (i.e., content-constrained) messages within five types of hazard events.     

Development of models for predicting biological age (BA) with physical, biochemical, and hormonal parameters

Individual differences are the hallmark of aging. Chronological age (CHA) is known that fails to provide an accurate indicator of the aging but biological age (BA) estimates the functional status of an individual in reference to his or her chronological peers on the basis of how well he or she functions in comparison with others of the same CHA. Therefore, we developed models for predicting BA that can be applicable in clinical practice settings. This was a community-based cross-sectional study. Subjects were recruited from the health promotion center in Korea from 2001 to 2005. Among these, data obtained from the 3575 participants (1302 men and 2273 women) was used for clinical evaluation and statistical analysis. For our test battery we selected 25 parameters among the routine tests. For males, the best models were developed using 15, 7, 5, and 4 of the 25 chosen parameters for total, physical, biochemical and hormonal characteristics, respectively (R(2)=0.62, 0.38, 0.33, and 0.36, respectively). Similar to males, for the females, 14, 6, 8, and 3 parameters were developed as the models (R(2)=0.66, 0.40, 0.42, and 0.37, respectively). Our BA prediction models may be used as supplementary tools adding knowledge in the evaluation of aging status.     

Brief Report: Shared partisanship dramatically increases social tie formation in a Twitter field experiment

Americans are much more likely to be socially connected to copartisans, both in daily life and on social media. However, this observation does not necessarily mean that shared partisanship per se drives social tie formation, because partisanship is confounded with many other factors. Here, we test the causal effect of shared partisanship on the formation of social ties in a field experiment on Twitter. We created bot accounts that self-identified as people who favored the Democratic or Republican party and that varied in the strength of that identification. We then randomly assigned 842 Twitter users to be followed by one of our accounts. Users were roughly three times more likely to reciprocally follow-back bots whose partisanship matched their own, and this was true regardless of the bot’s strength of identification. Interestingly, there was no partisan asymmetry in this preferential follow-back behavior: Democrats and Republicans alike were much more likely to reciprocate follows from copartisans. These results demonstrate a strong causal effect of shared partisanship on the formation of social ties in an ecologically valid field setting and have important implications for political psychology, social media, and the politically polarized state of the American public.     

#GeriMedJC: The Twitter Complement to the Traditional‐Format Geriatric Medicine Journal Club

Twitter is a public microblogging platform that overcomes physical limitations and allows unrestricted participation beyond academic silos, enabling interactive discussions. Twitter‐based journal clubs have demonstrated growth, sustainability, and worldwide communication, using a hashtag (#) to follow participation. This article describes the first year of #GeriMedJC, a monthly 1‐hour live, 23‐hour asynchronous Twitter‐based complement to the traditional‐format geriatric medicine journal club. The Twitter moderator tweets from the handle @GeriMedJC; encourages use of #GeriMedJC; and invites content experts, study authors, and followers to participate in critical appraisal of medical literature. Using the hashtag #GeriMedJC, tweets were categorized according to thematic content, relevance to the journal club, and authorship. Third‐party analytical tools Symplur and Twitter Analytics were used for growth and effect metrics (number of followers, participants, tweets, retweets, replies, impressions). Qualitative analysis of follower and participant profiles was used to establish country of origin and occupation. A semistructured interview of postgraduate trainees was conducted to ascertain qualitative aspects of the experience. In the first year, @GeriMedJC has grown to 541 followers on six continents. Most followers were physicians (43%), two‐thirds of which were geriatricians. Growth metrics increased over 12 months, with a mean of 121 tweets, 25 participants, and 105,831 impressions per journal club. Tweets were most often related to the article being appraised (87.5%) and ranged in thematic content from clinical practice (29%) to critical appraisal (24%) to medical education (20%). #GeriMedJC is a feasible example of using social media platforms such as Twitter to encourage international and interprofessional appraisal of medical literature.     

Virtual Zika transmission after the first U.S. case: who said what and how it spread on Twitter

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On the use of regression analysis for the estimation of human biological age

The present investigation compares three linear regression procedures for the definition of human biological age (bioage). As a model system for bioage definition is used the variations with age of blood hemoglobin (B-hemoglobin) in males in the age range 5095 years. The bioage measures compared are: 1: P-bioage; defined from regression of chronological age on B-hemoglobin results. 2: AC-bioage; obtained by indirect regression, using in reverse the equation describing the regression of B-hemoglobin on age in a reference population. 3: BC-bioage; defined by orthogonal regression on the reference regression line of B-hemoglobin on age. It is demonstrated that the P-bioage measure gives an overestimation of the bioage in the younger and an underestimation in the older individuals. This regression to the mean is avoided using the indirect regression procedures. Here the relatively low SD of the BC-bioage measure results from the inclusion of individual chronological age in the orthogonal regression procedure. Observations on male blood donors illustrates the variation of the AC- and BC-bioage measures in the individual.     

Women in Cardiology: Role of Social Media in Advocacy

Digital and social media have transformed the field of medicine. They are powerful tools that academic and non-academic physicians and healthcare providers are using to influence others, promote ideas, obtain knowledge, disseminate research and communicate with others. The history of advocacy for women in medicine and the role of social media in influencing the choice of women to choose Cardiology as a career and its role in advocacy for Women in Cardiology (WIC) have been reviewed. It has changed the way cardiologists learn, educate, and interact with each other. Social media has proven especially useful in advocating for WIC, but whether it can help improve the numbers of female doctors going into Cardiology remains to be seen. In addition to encouraging women to pursue cardiology, social media has drawn attention to key women’s rights issues affecting practicing female cardiologists.     

Relationship between gamma-irradiation, life span, metabolic rate and accumulation of fluorescent age pigment in the adult male housefly, Musca domestica

The patterns of fluorescent age pigment (FAP) accumulation in response to gamma-irradiation were examined in adult male houseflies under conditions of relatively high and low levels of physical activity. Flies were exposed to 0, 20, 40, and 66 kR and their level of physical activity was altered by permitting or restricting flight activity. Under conditions of high activity the mean life span of flies exposed to 20 kR and 40 kR was greater than in the controls. The mean life span of high activity flies exposed to 66 kR and all groups of low activity irradiated flies was less than the control life span. The force of mortality as indicated by Gompertz slope was greater in high activity controls than in unirradiated flies maintained under low activity conditions. Gompertz slope was similar in corresponding high and low activity groups exposed to radiation. Radiation decreased the rate of FAP accumulation in high activity groups, but increased the rate of FAP accumulation under low activity conditions. The low activity control and low activity flies exposed to 20 kR had a lower FAP accumulation than the corresponding high activity groups at 14 days of age. At this age, low activity groups of flies exposed to 40 kR and 66 kR had concentrations of FAP that were similar to the corresponding high activity groups. These results indicate that radiation exposure decreased longevity by causing damage rather than by increasing the rate of aging.     

Constructing an index of physical fitness age for Japanese elderly based on 7-year longitudinal data: sex differences in estimated physical fitness age

A standardized method for assessing the physical fitness of elderly adults has not yet been established. In this study, we developed an index of physical fitness age (fitness age score, FAS) for older Japanese adults and investigated sex differences based on the estimated FAS. Healthy elderly adults (52 men, 70 women) who underwent physical fitness tests once yearly for 7 years between 2002 and 2008 were included in this study. The age of the participants at the beginning of this study ranged from 60.0 to 83.0 years. The physical fitness tests consisted of 13 items to measure balance, agility, flexibility, muscle strength, and endurance. Three criteria were used to evaluate fitness markers of aging: (1) significant cross-sectional correlation with age; (2) significant longitudinal change with age consistent with the cross-sectional correlation; and (3) significant stability of individual differences. We developed an equation to assess individual FAS values using the first principal component derived from principal component analysis. Five candidate fitness markers of aging (10-m walking time, functional reach, one leg stand with eyes open, vertical jump and grip strength) were selected from the 13 physical fitness tests. Individual FAS was predicted from these five fitness markers using a principal component model. Individual FAS showed high longitudinal stability for age-related changes. This investigation of the longitudinal changes of individual FAS revealed that women had relatively lower physical fitness compared with men, but their rate of physical fitness aging was slower than that of men.     

Age-related de-phosporylation of proteins in dentin: A biological tool for assessment of protein age

Mature tooth dentin has essentially no metabolic activity, and thus post-translational modifications accumulate with aging in this tissue. In the present paper, we have studied age-related covalent changes of human dentin proteins. Dentin phosphoproteins (PP) were extracted and purified using ion exchange chromatography. Collagen was purified by CNBr cleavage and acetic acid extraction. The amino acid composition of the resultant protein preparations was determined by HPLC after post-column derivatization. Likewise the extent of aspartic acid (Asp) racemization was determined in total dentin, dentin collagen and PP. Collagen only displayed small, insignificant changes in amino acid composition and racemization with age. In contrast, PP exhibited significant age-related changes in amino acid composition, cross-linking and racemization. Thus the rate of Asp racemization in PP was 500-fold that found in collagen. Moreover, the phosphoserine (Ser(P)) content in human PP decreases dramatically with age, resulting in almost complete dephosphorylation over a life span. The loss of Ser(P) was accompanied by an increased content of the bifunctional cross-link histidinoalanine consistent with a -elimination pathway. The relative Ser(P) content was highly correlated with dentin age (r² = 0.96). The Ser(P) contents may thus potentially be applied in forensic investigations to deduce human age. The possible role of covalent modifications of the protein matrix in the degradation of mineralized tissue and its implications for the age-related decline of tissue functionality is discussed.     

Women's hierarchies of age and suffering in an Andean community

In the Aymara community of Utani, hierarchical relationships between middle aged and younger women are evident in the cycle of domestic life. An older woman — mother, sister, step mother, mother-in-law — has unquestioned authority as taskmistress over the labor of girls and young women; although very old women no longer wield such power. Post-marital residence patterns and the family life cycle contribute to the hierarchical relationships among women in an extended family household. When women's community-wide prestige is examined, however, a different pattern is apparent. Prestige among female peers is based less on age than on a woman's reputation for being long-suffering. The paper concludes that these two types of female hierarchy complement each other as part of women's adaptation to the exploitations of peasant life.     

Impact of age on care pathways of people living with HIV followed up in hospital

The aging population of people living with human immunodeficiency virus (HIV) (PLWH) is exposed to a widening spectrum of non-AIDS-defining diseases. Thus, our objective was to compare the health care offered to PLWH according to age. We conducted a multicenter cross-sectional study on PLWH who consulted at one of 59 French HIV reference centers from 15th to 19th October 2012. Using our survey questionnaires, PLWH self-reported the medical care they received, whether or not tied to HIV infection monitoring, during the previous year. A total of 650 PLWH participated in the survey (median age 48 years, Interquartile range (IQR) 40–54), of which 95 were aged 60 years or over (14.5%). Compared to younger PLWH, 60-and-over PLWH were more often under complementary health insurance cover and less socially deprived based on the French EPICES (Evaluation of Precarity and Inequalities in Health Examination Centers) score. The elderly PLWH presented more comorbidities and less coinfections with hepatitis viruses. During health care, therapeutic education was less often offered to older PLWH (14% vs. 26%, p?=?.01), but this difference was mainly explained by sociodemographic factors and clinical status. Over the previous 6 months, 74% of PLWH who were followed up in hospital had also consulted another doctor, with a mean of 3.75 consultations (±4.18) without difference between age groups. After adjustment for sociodemographic factors and comorbidities, PLWH over 60 years were more likely to have consulted medical specialists as outpatients in the last 6 months (odds ratio [OR]?=?2.63 [1.11–6.20]). Whatever their age, 13% of PLWH had been refused care on disclosure of their HIV status, and 27% of PLWH still did not disclose their HIV status to some caregivers. Coordinated health care throughout patients’ lives is crucial, as health-care pathways evolve toward outpatient care as the patients get older.     

Independent association between age and circadian systolic blood pressure patterns in adults with hypertension

Previous studies indicate a preliminary association between age and circadian blood pressure (BP) variation. This association would be affected by confounding factors in real‐world populations. The authors investigated whether this is a convincingly independent association in a real‐world population of adults with hypertension. Clinical data and findings of 24‐hour ambulatory BP monitoring were obtained from 297 consecutive adults with hypertension (60.19±0.77 years). BP dipping patterns were categorized based on the percentage of nocturnal BP drop. Multivariate linear regression analysis identified an independent correlation between age and percentage of nocturnal systolic BPdrop (β=−7.296; 95% CI, −10.430 to −4.162 [P<.001]). Reverse dippers were the oldest and extreme dippers were the youngest. A significant age difference was noted among patients grouped into four BP dipping patterns with and without adjustments for sex, body mass index, drugs, diabetes mellitus, smoking, 24‐hour mean heart rate, and 24‐hour mean systolic and diastolic BP.     

P—R间期与年龄和心率的相关性及校正公式

目的：研究Ｐ－Ｒ间期与年龄和心率的相关程度，建立依年龄和心率校正Ｐ－Ｒ间期的线性回归模型。方法：研究４０２３例健康婴儿、儿童及成人（出生至８０岁）Ｐ－Ｒ间期在不同年龄间和不同心率间的差别，用逐步回归分析拟合用年龄和心率校正Ｐ－Ｒ的线性回归模型。结果：证明Ｐ－Ｒ间期与年龄（Ｘ１）和心率（Ｘ２）有明显的相关关系，相关系数（ｒ）分别为０６８０（Ｐ＜００１）和－０６６１（Ｐ＜００１）。获得回归方程Ｙ＾（Ｐ－Ｒ）＝０．１５１＋０．０００５４２Ｘ１（年龄／岁）－００００２９７Ｘ２（心率，次／分），Ｒ＝０．７２６７，Ｓｘｙ＝．０．０１７，Ｘ１和Ｘ２的标准偏回归系数分别为ｂ’１＝０．４２９８和ｂ’２＝－０３５６６。结论：证明该公式（线性回归方程）能可靠的校正年龄及心率对Ｐ－Ｒ间期的影响