| 1. |
- Buitrago-Garcia, Diana, et al.
(författare)
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Occurrence and transmission potential of asymptomatic and presymptomatic SARS-CoV-2 infections : Update of a living systematic review and meta-analysis
- 2022
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Ingår i: PLoS Medicine. - : Public Library of Science (PLoS). - 1549-1277 .- 1549-1676. ; 19:5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Debate about the level of asymptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection continues. The amount of evidence is increasing and study designs have changed over time. We updated a living systematic review to address 3 questions: (1) Among people who become infected with SARS-CoV-2, what proportion does not experience symptoms at all during their infection? (2) What is the infectiousness of asymptomatic and presymptomatic, compared with symptomatic, SARS-CoV-2 infection? (3) What proportion of SARS-CoV-2 transmission in a population is accounted for by people who are asymptomatic or presymptomatic?Methods and findings: The protocol was first published on 1 April 2020 and last updated on 18 June 2021. We searched PubMed, Embase, bioRxiv, and medRxiv, aggregated in a database of SARS-CoV-2 literature, most recently on 6 July 2021. Studies of people with PCR-diagnosed SARS-CoV-2, which documented symptom status at the beginning and end of follow-up, or mathematical modelling studies were included. Studies restricted to people already diagnosed, of single individuals or families, or without sufficient follow-up were excluded. One reviewer extracted data and a second verified the extraction, with disagreement resolved by discussion or a third reviewer. Risk of bias in empirical studies was assessed with a bespoke checklist and modelling studies with a published checklist. All data syntheses were done using random effects models. Review question (1): We included 130 studies. Heterogeneity was high so we did not estimate a mean proportion of asymptomatic infections overall (interquartile range (IQR) 14% to 50%, prediction interval 2% to 90%), or in 84 studies based on screening of defined populations (IQR 20% to 65%, prediction interval 4% to 94%). In 46 studies based on contact or outbreak investigations, the summary proportion asymptomatic was 19% (95% confidence interval (CI) 15% to 25%, prediction interval 2% to 70%). (2) The secondary attack rate in contacts of people with asymptomatic infection compared with symptomatic infection was 0.32 (95% CI 0.16 to 0.64, prediction interval 0.11 to 0.95, 8 studies). (3) In 13 modelling studies fit to data, the proportion of all SARS-CoV-2 transmission from presymptomatic individuals was higher than from asymptomatic individuals. Limitations of the evidence include high heterogeneity and high risks of selection and information bias in studies that were not designed to measure persistently asymptomatic infection, and limited information about variants of concern or in people who have been vaccinated.Conclusions: Based on studies published up to July 2021, most SARS-CoV-2 infections were not persistently asymptomatic, and asymptomatic infections were less infectious than symptomatic infections. Summary estimates from meta-analysis may be misleading when variability between studies is extreme and prediction intervals should be presented. Future studies should determine the asymptomatic proportion of SARS-CoV-2 infections caused by variants of concern and in people with immunity following vaccination or previous infection. Without prospective longitudinal studies with methods that minimise selection and measurement biases, further updates with the study types included in this living systematic review are unlikely to be able to provide a reliable summary estimate of the proportion of asymptomatic infections caused by SARS-CoV-2.
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| 2. |
- Çevik, Müge, et al.
(författare)
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Sosyal Medya Analitiği [Social Media Analytics] : Twitter için Büyük Veri Yaklaşımı [Big Data Approach for Twitter]
- 2015
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Konferensbidrag (refereegranskat)abstract
- Bu çalışma, büyük veri analizini sosyal medya araştırmalarında kullanımı için yöntem önerisinde bulunmaktadır. Büyük veri araştırmalarında, tümden gelim ya da tüme varım yerine alternatif olarak “abduction” yaklaşımı kullanılabilir (Kitchin, 2014). Bu yaklaşımda veri, en iyi açıklamanın çıkarılması açısından araştırmanın başlangıcından sonuçlanmasına kadar geçen her aşamada dikkat edilmesi gereken önemli bir unsurdur. Sosyal medya araştırmalarında veri hacmi büyüklüğü ve verinin oluşum hızının yüksekliği sebebiyle, büyük veri analizi benimsenen yöntemler arasında öne çıkmaktadır (Jacob, 2009). Bu bağlamda, sosyal medya araştırmalarında analitik ve yapısal bir yöntemin takip edilmesi, araştırmaların ve çıktılarının bilimsel niteliğinin korunması açısından önem taşımaktadır. Çalışmamızın amacı, sosyal medya analitiğine örnek oluşturmak ve özellikle Twitter analizi için büyük veri analizine dayanan bir araştırma yöntemi önerisinde bulunmaktır.
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| 3. |
- Ozturkcan, Selcen, et al.
(författare)
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An analysis of the Gezi Park social movement tweets
- 2017
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Ingår i: Aslib Journal of Information Management. - : Emerald Group Publishing Limited. - 2050-3806 .- 2050-3814. ; 69:4, s. 426-440
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Twitter usage during Gezi Park Protests, a significant large-scale connective action, is analyzed to reveal meaningful findings on individual and group tweeting characteristics. Subsequent to the Arab Spring in terms of its timing, the Gezi Park Protests began by the spread of news on construction plans to build a shopping mall at a public park in Taksim Square in Istanbul on May 26, 2013. Though started as a small-scale local protest, it emerged into a series of multi-regional social protests, also known as the Gezi Park demonstrations. The paper aims to discuss these issues.Design/methodology/approach: The authors sought answers to three important research questions: whether Twitter usage is reflective of real life events, what Twitter is actually used for, and is Twitter usage contagious? The authors have collected streamed data from Twitter. As a research methodology, the authors followed social media analytics framework proposed by Fan and Gordon (2014), which included three consecutive processes; capturing, understanding, and presenting. An analysis of 54 million publicly available tweets and 3.5 million foursquare check-ins, which account to randomly selected 1 percent of all tweets and check-ins posted from Istanbul, Turkey between March and September 2013 are presented.Findings: A perceived lack of sufficient media coverage on events taking place on the streets is believed to result in Turkish protestors’ use of Twitter as a medium to share and get information on ongoing and planned demonstrations, to learn the recent news, to participate in the debate, and to create local and global awareness.Research limitations/implications: Data collection via streamed tweets comes with certain limitations. Twitter restricts data collection on publicly available tweets and only allows randomly selected 1 percent of all tweets posted from a specific region. Therefore, the authors’ data include only tweets of publicly available Twitter profiles. The generalizability of the findings should be regarded with concerning this limitation.Practical implications: The authors conclude that Twitter was used mainly as a platform to exchange information to organize street demonstrations.Originality/value: The authors conclude that Twitter usage reflected Street movements on a chronological level. Finally, the authors present that Twitter usage is contagious whereas tweeting is not necessarily.
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| 4. |
- Yurtman, Erinç, et al.
(författare)
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Archaeogenetic analysis of Neolithic sheep from Anatolia suggests a complex demographic history since domestication
- 2021
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Sheep were among the first domesticated animals, but their demographic history is little understood. Here we analyzed nuclear polymorphism and mitochondrial data (mtDNA) from ancient central and west Anatolian sheep dating from Epipaleolithic to late Neolithic, comparatively with modern-day breeds and central Asian Neolithic/Bronze Age sheep (OBI). Analyzing ancient nuclear data, we found that Anatolian Neolithic sheep (ANS) are genetically closest to present-day European breeds relative to Asian breeds, a conclusion supported by mtDNA haplogroup frequencies. In contrast, OBI showed higher genetic affinity to present-day Asian breeds. These results suggest that the east-west genetic structure observed in present-day breeds had already emerged by 6000 BCE, hinting at multiple sheep domestication episodes or early wild introgression in southwest Asia. Furthermore, we found that ANS are genetically distinct from all modern breeds. Our results suggest that European and Anatolian domestic sheep gene pools have been strongly remolded since the Neolithic.
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