Wikipedia

Die kostenlose und freie Enzyklopädie Wikipedia ist ein sehr erfolgreiches "Open Content"-Projekt, das auf der unentgeltlichen Zusammenarbeit vieler freiwilliger Autoren beruht. Inzwischen zählt Wikipedia zu den zehn populärsten Webseiten der Welt, und empirische Untersuchungen belegen eine überwiegend hohe Qualität der Beiträge. Bislang ist allerdings nur wenig darüber bekannt, aus welchen Gründen Personen an Wikipedia mitarbeiten. In einer Reihe von empirischen Studien wurden daher die auslösenden und aufrechterhaltenden motivationalen Einflussfaktoren der freiwilligen Mitarbeit an Wikipedia untersucht. Den theoretischen Bezugsrahmen bildeten zentrale Theorien zur Teilnahme an sozialen Bewegungen einerseits und zum Einfluss der Merkmale einer Tätigkeit andererseits (z. B. Autonomie, Feedback, etc.). Zunächst wurden in einer deutschsprachigen und einer internationalen Studie jeweils sehr aktive Wikipedia-Autoren zu den Gründen ihres Engagements befragt. Die Ergebnisse zeigen, dass die Merkmale der Tätigkeit für Wikipedia (insb. Autonomie, Rückmeldung und die Bedeutsamkeit der Tätigkeit) zu einer höheren intrinsischen Motivation führten (d. h., Freude an und Aufgehen in der Tätigkeit), die wiederum das selbstberichtete Engagement für Wikipedia vorhersagte (z. B. aufgewendete Zeit). Personen, die sich stärker für Wikipedia engagierten, schätzten das Verhältnis von Kosten und Nutzen ungünstiger ein als weniger engagierte Personen. Andererseits waren Autoren, die Verhältnis von Kosten und Nutzen günstiger bewerteten, zufriedener mit ihrem Engagement für Wikipedia. Wichtig war auch die Identifikation mit Wikipedia, wohingegen die individuelle Bedeutsamkeit der von Wikipedia vertretenen Ziele (v. a. freier Zugang zu Wissen) trotz sehr hoher Ausprägung weder das Ausmaß des Engagements noch die Zufriedenheit mit dem Engagement vorhersagte. Schließlich wurde in einer Befragung von Wikipedia-Lesern untersucht, aus welchen Gründen bislang nicht aktive Personen sich zum ersten Mal an Wikipedia beteiligten. Wichtig für die Teilnahmebereitschaft bzw. die tatsächliche Beteiligung sechs Monate später waren das wahrgenommene Kosten-Nutzen-Verhältnis, die erwartete Freude an der Tätigkeit und die Bedeutsamkeit des eigenen Beitrags, die vor allem aufgrund von fehlenden Informationen in Wikipedia deutlich wurde. Die persönliche Bedeutung des Ideals von freiem Wissen förderte das Interesse an Wikipedia, war aber kein hinreichender Grund, sich zu beteiligen. Diese Ergebnisse können bedeutsam dafür sein, neue Autoren für Wikipedia zu gewinnen und aktive Autoren längerfristig zu motivieren. Konsequenzen für andere Web-2.0-Projekte und das Wissensmanagement in Organisationen werden diskutiert

Transmembrane domain length of viral K+ channels is a signal for mitochondria targeting

K+ channels operate in the plasma membrane and in membranes of organelles including mitochondria. The mechanisms and topogenic information for their differential synthesis and targeting is unknown. This article describes 2 similar viral K+ channels that are differentially sorted; one protein (Kesv) is imported by the Tom complex into the mitochondria, the other (Kcv) to the plasma membrane. By creating chimeras we discovered that mitochondrial sorting of Kesv depends on a hierarchical combination of N- and C-terminal signals. Crucial is the length of the second transmembrane domain; extending its C terminus by \u3e2 hydrophobic amino acids redirects Kesv from the mitochondrial to the plasma membrane. Activity of Kesv in the plasma membrane is detected electrically or by yeast rescue assays only after this shift in sorting. Hence only minor structural alterations in a transmembrane domain are sufficient to switch sorting of a K+ channel between the plasma membrane and mitochondria

50 Jahre „Unterrichtswissenschaft – Zeitschrift für Lernforschung“ – Jubiläumsheft I

Die Unterrichtswissenschaft feiert ein Jubiläum – sie erscheint im Jahr 2023 seit 50 Jahren. Dieser Beitrag ist die Einführung für das Jubiläumsheft (Heft 1, 2023). Er stellt zunächst die Gründung der Zeitschrift dar. Anhand der Protokolle der Herausgebersitzungen wird skizziert, wie sich die „Unterrichtswissenschaft“ als Zeitschrift der empirischen Lehr-Lernforschung entwickelt hat und welche Herausforderungen dabei zu bewältigen waren. Abschließend werden die bisherigen Überlegungen der derzeitigen Herausgeber*innen für die Entwicklung der Zeitschrift und der Lehr-Lern-Forschung vorgestellt

Forschungsstudie: Alterssicherung von Personen mit Migrationshintergrund; Endbericht zum Auftrag des BMAS, Projektgruppe "Soziale Sicherheit und Migration" vom 02.01.2009

Aufgrund der demographischen Entwicklung und unter Annahme weitgehend stabiler Remigrationsmuster ist ein Anstieg des Bevölkerungsanteils älterer Menschen mit Migrationshintergrund zu erwarten. Viele der derzeit in Deutschland lebenden Migranten werden daher ihren Lebensabend hier verbringen. Ziel dieser Studie ist die vergleichende Darstellung der sozioökonomischen Lage der Migrantenpopulation und der autochthonen Bevölkerung. Dabei wird die Lebenslage von Personen im Rentenalter und von älteren Erwerbspersonen ab 45 Jahren vor dem Hintergrund ihrer spezifischen Bildungs- und Erwerbsverläufe untersucht. Damit wird eine belastbare empirische Grundlage für Handlungsempfehlungen zur Verbesserung der sozialen Lage von Frauen und Männern mit Migrationshintergrund im Alter geliefert

Associations of Preconception Exposure to Air Pollution and Greenness with Offspring Asthma and Hay Fever

We investigated if greenness and air pollution exposure in parents' childhood affect offspring asthma and hay fever, and if effects were mediated through parental asthma, pregnancy greenness/pollution exposure, and offspring exposure. We analysed 1106 parents with 1949 offspring (mean age 35 and 6) from the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) generation study. Mean particulate matter (PM(2.5)and PM10), nitrogen dioxide (NO2), black carbon (BC), ozone (O-3) (mu g/m(3)) and greenness (normalized difference vegetation index (NDVI)) were calculated for parents 0-18 years old and offspring 0-10 years old, and were categorised in tertiles. We performed logistic regression and mediation analyses for two-pollutant models (clustered by family and centre, stratified by parental lines, and adjusted for grandparental asthma and education). Maternal medium PM(2.5)and PM(10)exposure was associated with higher offspring asthma risk (odds ratio (OR) 2.23, 95%CI 1.32-3.78, OR 2.27, 95%CI 1.36-3.80), and paternal high BC exposure with lower asthma risk (OR 0.31, 95%CI 0.11-0.87). Hay fever risk increased for offspring of fathers with medium O(3)exposure (OR 4.15, 95%CI 1.28-13.50) and mothers with high PM(10)exposure (OR 2.66, 95%CI 1.19-5.91). The effect of maternal PM(10)exposure on offspring asthma was direct, while for hay fever, it was mediated through exposures in pregnancy and offspring's own exposures. Paternal O(3)exposure had a direct effect on offspring hay fever. To conclude, parental exposure to air pollution appears to influence the risk of asthma and allergies in future offspring

Associations of preconception exposure to air pollution and greenness with offspring asthma and hay fever

We investigated if greenness and air pollution exposure in parents’ childhood affect offspring asthma and hay fever, and if effects were mediated through parental asthma, pregnancy greenness/pollution exposure, and offspring exposure. We analysed 1106 parents with 1949 offspring (mean age 35 and 6) from the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) generation study. Mean particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), black carbon (BC), ozone (O3) (µg/m3) and greenness (normalized difference vegetation index (NDVI)) were calculated for parents 0-18 years old and offspring 0-10 years old, and were categorised in tertiles. We performed logistic regression and mediation analyses for two-pollutant models (clustered by family and centre, stratified by parental lines, and adjusted for grandparental asthma and education). Maternal medium PM2.5 and PM10 exposure was associated with higher offspring asthma risk (odds ratio (OR) 2.23, 95%CI 1.32-3.78, OR 2.27, 95%CI 1.36-3.80), and paternal high BC exposure with lower asthma risk (OR 0.31, 95%CI 0.11-0.87). Hay fever risk increased for offspring of fathers with medium O3 exposure (OR 4.15, 95%CI 1.28-13.50) and mothers with high PM10 exposure (OR 2.66, 95%CI 1.19-5.91). The effect of maternal PM10 exposure on offspring asthma was direct, while for hay fever, it was mediated through exposures in pregnancy and offspring’s own exposures. Paternal O3 exposure had a direct effect on offspring hay fever. To conclude, parental exposure to air pollution appears to influence the risk of asthma and allergies in future offspring

Elaia, Pergamon's maritime satellite:The rise and fall of an ancient harbour city shaped by shoreline migration

Throughout human history, communication and trade have been key to society. Because maritime trade facilitated the rapid transportation of passengers and freight at relatively low cost, harbours became hubs for traffic, trade and exchange. This general statement holds true for the Pergamenian kingdom, which ruled wide parts of today's western Turkey during Hellenistic times. Its harbour, located at the city of Elaia on the eastern Aegean shore, was used extensively for commercial and military purposes. This study reconstructs the coastal evolution in and around the ancient harbour of Elaia and compares the observed environmental modifications with archaeological and historical findings. We use micropalaeontological, sedimentological and geochemical proxies to reconstruct the palaeoenvironmental dynamics and evolution of the ancient harbour. The geoarchaeological results confirm the archaeological and historical evidence for Elaia's primacy during Hellenistic and early Roman times, and the city's gradual decline during the late Roman period. Furthermore, our study demonstrates that Elaia holds a unique position as a harbour city during ancient times in the eastern Aegean region, because it was not greatly influenced by the high sediment supply associated with river deltas. Consequently, no dredging of the harbour basins is documented, creating exceptional geo-bioarchives for palaeoenvironmental reconstructions

Distance to high-voltage power lines and risk of childhood leukemia:An analysis of confounding by and interaction with other potential risk factors

We investigated whether there is an interaction between distance from residence at birth to nearest power line and domestic radon and traffic-related air pollution, respectively, in relation to childhood leukemia risk. Further, we investigated whether adjusting for potential confounders alters the association between distance to nearest power line and childhood leukemia. We included 1024 cases aged <15, diagnosed with leukemia during 1968-1991, from the Danish Cancer Registry and 2048 controls randomly selected from the Danish childhood population and individually matched by gender and year of birth. We used geographical information systems to determine the distance between residence at birth and the nearest 132-400 kV overhead power line. Concentrations of domestic radon and traffic-related air pollution (NOx at the front door) were estimated using validated models. We found a statistically significant interaction between distance to nearest power line and domestic radon regarding risk of childhood leukemia (p = 0.01) when using the median radon level as cut-off point but not when using the 75th percentile (p = 0.90). We found no evidence of an interaction between distance to nearest power line and traffic-related air pollution (p = 0.73). We found almost no change in the estimated association between distance to power line and risk of childhood leukemia when adjusting for socioeconomic status of the municipality, urbanization, maternal age, birth order, domestic radon and traffic-related air pollution. The statistically significant interaction between distance to nearest power line and domestic radon was based on few exposed cases and controls and sensitive to the choice of exposure categorization and might, therefore, be due to chance

Cyclic stretch increases splicing noise rate in cultured human fibroblasts

BACKGROUND: Mechanical forces are known to alter the expression of genes, but it has so far not been reported whether they may influence the fidelity of nucleus-based processes. One experimental approach permitting to address this question is the application of cyclic stretch to cultured human fibroblasts. As a marker for the precision of nucleus-based processes, the number of errors that occur during co-transcriptional splicing can then be measured. This so-called splicing noise is found at low frequency in pre-mRNA splicing. FINDINGS: The amount of splicing noise was measured by RT-qPCR of seven exon skips from the test genes AATF, MAP3K11, NF1, PCGF2, POLR2A and RABAC1. In cells treated by altered uniaxial cyclic stretching for 18 h, a uniform and significant increase of splicing noise was found for all detectable exon skips. CONCLUSION: Our data demonstrate that application of cyclic stretch to cultured fibroblasts correlates with a reduced transcriptional fidelity caused by increasing splicing noise