“Thanks for sharing”—Identifying users’ roles based on knowledge contribution in Enterprise Social Networks

While ever more companies use Enterprise Social Networks for knowledge management, there is still a lack of understanding of users' knowledge exchanging behavior. In this context, it is important to be able to identify and characterize users who contribute and communicate their knowledge in the network and help others to get their work done. In this paper, we propose a new methodological approach consisting of three steps, namely "message classification", "identification of users' roles" as well as "characterization of users' roles". We apply the approach to a dataset from a multinational consulting company, which allows us to identify three user roles based on their knowledge contribution in messages: givers, takers, and matchers. Going beyond this categorization, our data shows that whereas the majority of messages aims to share knowledge, matchers, that means people that give and take, are a central element of the network. In conclusion, the development and application of a new methodological approach allows us to contribute to a more refined understanding of users' knowledge exchanging behavior in Enterprise Social Networks which can ultimately help companies to take measures to improve their knowledge management. (C) 2018 Elsevier B.V. All rights reserved

Investigating Maar Formation and the climate history of Southern Argentina–the Potrok Aike Maar Lake Sediment Archive Drilling Project (PASADO)

Evidence is increasing that the Southern Ocean plays a key role in the global climate system. The southern hemisphere contains more than 90% of the world’s ice, and eighty-one percent of its total surface area is covered by oceans. On global terms, the most extreme oceanic character is encountered between 40°S and 60°S latitude, where land (Patagonia and a few islands) comprises only 2% of the surface area. Terrestrial archives of past climate changes are thus extremely scarce at these latitudes. As Patagonia is subject to shifts in polar and mid-latitude winds, pressure fi elds, and precipitation regimes, as well as to variations related to the El Niño Southern Oscillation (ENSO) and the Antarctic Oscillation (AO), it has the unique potential to record variations in the hydrological cycle, changes in aeolian dust deposition, the frequency of volcanic activity, and other natural forces that control climatic conditions. Lake sediments can provide important archives for such terrestrial climatic and environmental reconstructions. In the semi-arid steppe region of Patagonia, however, most of the lakes are periodically dry or ephemeral. One exception is the 100-m-deep crater lake Laguna Potrok Aike (Fig. 1), a 770 ± 220 thousand year old maar situated in the province of Santa Cruz, Argentina. The lake is located in the Pali Aike Volcanic Field (Fig. 2), the southernmost back-arc Neozoic volcanic fi eld of South America. As Laguna Potrok Aike has not been reached by any Pleistocene ice advance during the last 1 Ma, it is potentially the only mid-latitude lake in the Southern Hemisphere with a continuous sedimentary record covering several glacial to interglacial cycles. In addition to global reconstructions, regional climatic variations represent other important aspects of research.Fil: Zolitschka, Bernd. Universitat Bremen; AlemaniaFil: Corbella, Hugo. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Maidana, Nora Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ohlendorf, Christian. Universitat Bremen; Alemani

Spätquartäre Sedimentationsgeschichte des Meerfelder Maares (Westeifel).—Mikrostratigraphie jahreszeitlich geschichteter Seesedimente

Zwei Sedimentkerne aus dem zentralen Teil des Meerfelder Maares wurden mikrostratigraphisch ausgewertet. Diatomologische Untersuchungen weisen die überwiegend organischen Ablagerungen als jahreszeitlich geschichtet aus. Die daraufhin durchgeführte Warvenzählung erlaubt es, jeden Sedimentabschnitt absolut zu datieren. Klimaschwankungen und anthropogene Einflüsse können nachgewiesen und datiert werden. Sie steuern den wechselnden Sedimentaufbau und erklären die unterschiedlichen Sedimentationsraten.researc

Social Mechanisms in Epidemiological Publications on Small-Area Health Inequalities-A Scoping Review

Zolitschka KA, Razum O, Breckenkamp J, Sauzet O. Social Mechanisms in Epidemiological Publications on Small-Area Health Inequalities-A Scoping Review. FRONTIERS IN PUBLIC HEALTH. 2019;7: 393.Background: Small-area social mechanisms-social processes involving the social environment around the place of residence-may be playing a role in the production of health inequalities. Understanding how small-area health inequalities (social environment affects health and consequently contribute to inequalities between areas) are generated and the role of social mechanisms in this process may help defining interventions to reduce inequalities. In mediation and pathway analyses, social mechanisms need to be treated as processes or factors. We aimed to identify which types of social mechanisms explaining the process leading from small-area characteristics to health inequalities have been considered and investigated in epidemiological publications and to establish how they have been operationalized. Methods: We performed a scoping review for social mechanisms in the context of small-area health inequalities in the database PubMed. Epidemiological publications identified were categorized according to the typology proposed by Galster (social networks, social contagion, collective socialization, social cohesion, competition, relative deprivation, and parental mediation). Furthermore, we assessed whether the mechanisms were operationalized at the micro or macro level and whether mechanisms were considered as processes or merely as exposure factors. Results: We retrieved 1,019 studies, 15 thereof were included in our analysis. Eight forms of operationalization were found in the category social networks and another nine in the category social cohesion. Other categories were hardly represented. Furthermore, all studies were cross sectional and did not consider mechanisms as processes. Except for one, all studies treated mechanisms merely as factors whose respective association to health outcomes was tested. Conclusion: In epidemiological publications, social mechanisms in studies on small-area effects on health inequalities are not operationalized as processes in which these mechanisms would play a role. Rather, the focus is on studying associations. To understand the production of health inequalities and the causal effect of social mechanisms on health, it is necessary to analyze mechanisms as processes. For this purpose, methods such as complex system modeling should be considered

Können kleinräumige, gesundheitliche Ungleichheiten durch nachbarschaftlich mediierte, soziale Mechanismen reduziert werden?

Zolitschka KA. Können kleinräumige, gesundheitliche Ungleichheiten durch nachbarschaftlich mediierte, soziale Mechanismen reduziert werden?. Bielefeld: Universität Bielefeld; 2020

Does social cohesion mediate neighbourhood effects on mental and physical health? Longitudinal analysis using German Socio-Economic Panel data

Kress S, Razum O, Zolitschka KA, Breckenkamp J, Sauzet O. Does social cohesion mediate neighbourhood effects on mental and physical health? Longitudinal analysis using German Socio-Economic Panel data. BMC Public Health. 2020;20: 1043.Background Neighbourhood has risen as a relevant determinant of health. While there is substantial evidence that environmental factors affect health, far less evidence of the role of social mechanisms in the causal chain between neighbourhood characteristics and health is available. Method To evaluate the role of social cohesion as a mediator between four different neighbourhood characteristics and health using data from German Socio-Economic-Panel (SOEP), a longitudinal mediation analysis was performed. Multilevel linear regression models adjusted for socio-economic variables involved three time points and two measures of physical and mental health (physical and mental component scores (PCS and MCS) of the SF12 Questionnaire. Participants were followed-up for 4 and 10 year starting in 2004. Results A total of 15,518 measures of MCS and PCS on 10,013 participants living in 4985 households were included. After adjusting for values of MCS and PCS at baseline and demographic/socio-economic variables, social cohesion was a significant positive predictor of both MCS and PCS (β-coefficient MCS: 1.57 (0.27); PCS: 1.50 (0.24)). Interaction between social cohesion and follow-up were significant for PCS. The effect of environmental and built characteristics on health was consistently mediated by social cohesion with proportion varying between 10 and 23%. Discussion We show that social cohesion is part of the causal chain between environmental and built characteristics of a neighbourhood and health, with increasing mediation effect over time for physical health. Social mechanisms should be considered when studying the effect of neighbourhood characteristics on health inequalities making social cohesion as a legitimate target of public health interventions at neighbourhood level

Responses of testate amoebae assemblages (Amoebozoa: Arcellinida) to recent volcanic eruptions, inferred from the sediment record in Laguna Verde, southern Patagonia, Argentina

There is little knowledge about testate amoebae in lakes and their responses to volcanic eruptions. To address this knowledge gap, we studied the paleoecology of these protists in a sediment record from Laguna Verde, a lake located east of the southern Patagonian Ice Field, in Santa Cruz Province, Argentina. The lake is under the influence of volcanic eruptions from Lautaro Volcano, Chile, ~ 42 km WNW of Laguna Verde. We evaluated the response of 11 testate amoeba morphospecies in the lake to the last four Lautaro eruptions, using a 61-cm sediment core. Calcium (Ca), a major element of volcanic ash, was the most important variable explaining testate amoeba variability in the three zones determined by detretended correspondence analysis. We identified four declines in testate amoeba abundance and diversity associated with tephra deposition. Poisson regression analysis revealed that Difflugia immanata, D. bidens, and D. glans strain “glans” decrease after deposition of tephra layers. In contrast, Centropyxis constricta strain “constricta,” C. aculeata strain “aculeata” and Zivkovicia compressa respond positively to ash deposition. Our findings suggest a high resilience of testate amoebae to stochastic events such as volcanism because the same assemblage (D. immanata, D. bidens, and D. glans strain “glans”) inhabited the lake before and after the ashfalls. Nevertheless, several volcanic eruptions during the last ~ 300 years may have weakened this resilience and had a long-term effect on community diversity. Multivariate analysis showed that potassium (K) plays a significant role in shaping assemblage composition. Because of the low K content of the Lautaro tephra, we infer that higher potassium concentrations in sediments are not related with volcanic events, but rather, are associated with terrestrial input. Future studies, however, will be needed to identify the source of K in the sediment record and its relationship with testate amoebae assemblages. Our study demonstrates the potential for using lacustrine testate amoebae as environmental proxies, and illustrates the direct effects of volcanic ash deposition on their assemblage composition, diversity and distribution in southern Patagonia.Fil: Charqueño Celis, Norma Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi"; ArgentinaFil: Sigala, Itzel. Universidad Nacional Autónoma de México. Instituto de Geofísica; MéxicoFil: Zolitschka, Bernd. Universitat Bremen. Institut Fuer Geographie; AlemaniaFil: Pérez, Liseth. Technische Universitat Carolo Wilhelmina Zu Braunschweig. Iinstitut fur Geosysteme und Bioindikation; AlemaniaFil: Mayr, Christoph. Institut Fur Geographie, Friedrich-alexander-universit; Alemania. Universitat Erlangen Nuremberg; Alemania. Ludwig Maximilians Universitat; AlemaniaFil: Massaferro, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi"; Argentin

New vegetation history reconstructions suggest a biostratigraphic assignment of the lowermost Rodderberg interglacial (Germany) to MIS 11

Along with the ongoing climate crisis, research efforts increasingly focus on Pleistocene environmental archives. Interglacial periods are of special interest, as they offer crucial information about natural interactions (i.e. not influenced by human activities) between climate and ecosystems within a climatic setting comparable to the Holocene and/or climate change projections. The sedimentary infill of the Rodderberg crater, 10 km south of the city of Bonn (Germany), records several glacial-interglacial cycles in superposition, which makes it a rare and promising environmental archive. One of the most challenging targets is to establish a robust chronological framework for the Rodderberg sediment sequence. In the present study we reconstruct the vegetation history of the basal and most prominent interglacial sequence, the lowermost Rodderberg interglacial (LRI), and apply the principles of pollen biostratigraphy to estimate the depositional age. At the base of the sequence steppe tundra conditions prevailed during the cryocratic phase before the onset of the interglacial. Rising temperatures caused afforestation of the landscape with boreal forests during the protocratic phase, which subsequently were replaced by temperate forests in the mesocratic phase. The sequence continues under unstable vegetation conditions characterized by temperate forests dominated by Carpinus and Abies during the oligocratic phase. During the terminal part of the LRI, the telocratic phase, boreal to nemoboreal forests covered the landscape. Due to climatic deterioration these forests collapsed and a steppe tundra evolved again (cryocratic phase). This climate-driven glacial-interglacial cycle is followed by an interstadial with rather closed nemoboreal forest vegetation. Based on the occurrences of characteristic taxa as well as the vegetation assemblages and succession, we refrain from correlating the LRI with any of the warm stages between c. 240 and 180 ka BP, i.e. roughly corresponding to MIS 7. A correlation with the Holsteinian, which was previously physically dated to c. 340e325 ka BP, cannot unambiguously be excluded, however, the absence of Pterocarya during the LRI argues against it. Instead, the LRI has striking similarities with the Kärlich interglacial, which has been previously physically dated to c. 400 ka BP, making it chronologically equivalent to MIS 11

Origin and evolution of the Laguna Potrok Aike maar (Patagonia, Argentina)

Laguna Potrok Aike, a maar lake in southern-most Patagonia, is located at about 110 m a.s.l. in the Pliocene to late Quaternary Pali Aike Volcanic Field (Santa Cruz, southern Patagonia, Argentina) at about 52°S and 70°W, some 20 km north of the Strait of Magellan and approximately 90 km west of the city of Rio Gallegos. The lake is almost circular and bowl-shaped with a 100 m deep, flat plain in its central part and an approximate diameter of 3.5 km.Steep slopes separate the central plain from the lake shoulder at about 35 m water depth. At present, strong winds permanently mix the entire water column. The closed lake basin contains a sub saline water body and has only episodic inflows with the most important episodic tributary situated on the western shore. Discharge is restricted to major snowmelt events.Laguna Potrok Aike is presently located at the boundary between the Southern Hemispheric Westerlies and the Antarctic Polar Front. The sedimentary regime is thus influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern HemisphericWesterlies and sporadic outbreaks of Antarctic polar air masses. Previous studies demonstrated that closed lakes in southern South America are sensitive to variations in the evaporation/precipitation ratio and have experienced drastic lake level changes in the past causing for example the desiccation of the 75 m deep Lago Cardiel during the Late Glacial. Multiproxy environmental reconstruction of the last 16 ka documents that Laguna Potrok Aike is highly sensitive to climate change. Based on an Ar/Ar age determination, the phreatomagmatic tephra that is assumed to relate to the Potrok Aike maar eruption was formed around 770 ka. Thus Laguna Potrok Aike sediments contain almost 0.8 million years of climate history spanning several past glacial-interglacial cycles making it a unique archive for non-tropical and non-polar regions of the Southern Hemisphere. In particular, variations of the hydrological cycle, changes in eolian dust deposition, frequencies and consequences of volcanic activities and other natural forces controlling climatic and environmental responses can be tracked throughout time. Laguna Potrok Aike has thus become a major focus of the International Continental Scientific Drilling Program. Drilling operations were carried out within PASADO (Potrok Aike Maar Lake Sediment Archive Drilling Project) in late 2008 and penetrated ~100 m into the lacustrine sediment.Laguna Potrok Aike is surrounded by a series of subaerial paleo-shorelines of modern to Holocene age that reach up to 21 m above the 2003 AD lake level. An erosional unconformity which can be observed basin-wide along the lake shoulder at about 33 m below the 2003 AD lake level marks the lowest lake level reached during Late Glacial to Holocene times. A high- resolution seismic survey revealed a series of buried, subaquatic paleo-shorelines that hold a record of the complex transgressional history of the past approximately 6800 years, which was temporarily interrupted by two regressional phases from approximately 5800 to 5400 and 4700 to 4000 cal BP. Seismic reflection and refraction data provide insights into the sedimentary infill and the underlying volcanic structure of Laguna Potrok Aike. Reflection data show undisturbed, stratified lacustrine sediments at least in the upper ~100 m of the sedimentary infill. Two stratigraphic boundaries were identified in the seismic profiles (separating subunits I-ab, I-c and I-d) that are likely related to changes in lake level. Subunits I-ab and I-d are quite similar even though velocities are enhanced in subunit I-d. This might point at cementation in subunit I-d. Subunit I-c is restricted to the central parts of the lake and thins out laterally.A velocity-depth model calculated from seismic refraction data reveals a funnel-shaped structure embedded in the sandstone rocks of the surrounding Santa Cruz Formation. This funnel struc