Stockholm University

About: Stockholm University is a education organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Population & Supernova. The organization has 21052 authors who have published 62567 publications receiving 2725859 citations. The organization is also known as: University of Stockholm & Stockholms universitet.

Blocking Action in the Middle Troposphere and its Effect upon Regional Climate

Abstract: The results of a semi-statistical study of 112 cases of blocking action in the upper westerlies are presented; areas of most frequent occurrence, characteristic movement and persistence, and seasonal and yearly trends of blocking activity are determined The regional precipitation and mean surface-temperature anomalies associated with blocking over Europe are illustrated and compared with those produced by strong zonal flow aloft The effects produced by variations in blocking activity upon European climatic trends are discussed The influence of blocking action upon Scandinavian glaciation and certain indications as to the role played by blocking in an ice-age climatic cycle are discussed DOI: 101111/j2153-34901950tb00339x

Vertical structure of recent Arctic warming

Abstract: Near-surface warming in the Arctic has been almost twice as large as the global average over recent decades1, 2, 3, 4, 5—a phenomenon that is known as the 'Arctic amplification'. The underlying cau ...

Estimation of census and effective population sizes: the increasing usefulness of DNA-based approaches

Abstract: Population census size (NC) and effective population sizes (Ne) are two crucial parameters that influence population viability, wildlife management deci- sions, and conservation planning. Genetic estimators of both NC and Ne are increasingly widely used because molecular markers are increasingly available, statistical methods are improving rapidly, and genetic estimators complement or improve upon traditional demographic estimators. We review the kinds and applications of estimators of both NC and Ne, and the often undervalued and misunderstood ratio of effective-to-census size (Ne/NC). We focus on recently improved and well evalu- ated methods that are most likely to facilitate conservation. Finally, we outline areas of future research to improve Ne and NC estimation in wild populations.

Learning loss due to school closures during the COVID-19 pandemic.

Abstract: Suspension of face-to-face instruction in schools during the COVID-19 pandemic has led to concerns about consequences for students' learning. So far, data to study this question have been limited. Here we evaluate the effect of school closures on primary school performance using exceptionally rich data from The Netherlands (n ≈ 350,000). We use the fact that national examinations took place before and after lockdown and compare progress during this period to the same period in the 3 previous years. The Netherlands underwent only a relatively short lockdown (8 wk) and features an equitable system of school funding and the world's highest rate of broadband access. Still, our results reveal a learning loss of about 3 percentile points or 0.08 standard deviations. The effect is equivalent to one-fifth of a school year, the same period that schools remained closed. Losses are up to 60% larger among students from less-educated homes, confirming worries about the uneven toll of the pandemic on children and families. Investigating mechanisms, we find that most of the effect reflects the cumulative impact of knowledge learned rather than transitory influences on the day of testing. Results remain robust when balancing on the estimated propensity of treatment and using maximum-entropy weights or with fixed-effects specifications that compare students within the same school and family. The findings imply that students made little or no progress while learning from home and suggest losses even larger in countries with weaker infrastructure or longer school closures.

Social media and the organization of collective action : using Twitter to explore the ecology of two climate change protests

Abstract: The Twitter Revolutions of 2009 reinvigorated the question of whether new social media have any real effect on contentious politics. In this article, the authors argue that evaluating the relation between transforming communication technologies and collective action demands recognizing how such technologies infuse specific protest ecologies. This includes looking beyond informational functions to the role of social media as organizing mechanisms and recognizing that traces of these media may reflect larger organizational schemes. Three points become salient in the case of Twitter against this background: (a) Twitter streams represent crosscutting networking mechanisms in a protest ecology, (b) they embed and are embedded in various kinds of gatekeeping processes, and (c) they reflect changing dynamics in the ecology over time. The authors illustrate their argument with reference to two hashtags used in the protests around the 2009 United Nations Climate Summit in Copenhagen.