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Makers of a future journalism? The role of pioneer journalists and pioneer communities in transforming journalism
Get PDFIn this paper, we want to discuss the role pioneer journalists and the pioneer communities that they are part of may play in journalism s trajectory going forward. Journalism serves as an ideal case study for such an undertaking. This is because the transformation of jour- nalism is entangled with the development of media technologies and is increasingly main- tained beyond the newsroom by actors outside established media organisations, who are situated more at the periphery of the journalistic field not yet being part of the main- stream. For a couple of examples, one can look at the Hacks/Hackers movement who are engaged in data- and technology-driven journalism (Lewis and Usher, 2014), or the Con- structive Journalism Project (www.constructivejournalism.org), which are both develop- ing new forms of media coverage that integrates solution-focused elements (Haagerup, 2014). The starting point of our paper is that such forms of pioneering are a more general phenomenon in journalism. What pioneers or pioneer communities imagine is not a collec- tion of straightforward models that can be readily applied to current mainstream jour- nalism, but something that is likely to have a remarkable impact on discourse surrounding its future - something that signals developments and practices of pioneers and innovators at the periphery that push towards the centre
Mikroelektroden für die chronische Ableitung und Stimulation neuronaler Aktivität im Kortex
Get PDFFor neuroscience an experimental access to the individual neurons is essential to investigate e.g. the interaction of different brain areas. A basic challenge therefor is the long-term stable, electrical interface to the neurons for in-vivo experiments over several months or even years. Due to the inflammatory response of the neural tissue to the foreign body a scar is created around the neural probe with the microelectrodes, so that the electrical access for recording and stimulation of neural activity in the cortex is hindered or even impossible. The present dissertation contains the development of novel neural probes with the goal to reduce the inflammatory response and enable a chronic neural interface. The therefor developed, silicon-based microfabrication process enables a monolithical integration of the neural probes with highly flexible, electrical conducting paths to reduce the mechanical coupling during micromotion of the cortex relative to the skull and thus the irritation of the neural tissue. The developed microfabrication process allows the integration of in total 18 microelectrodes on a linear probe with a rectangular cross section of only 130 Amicrometre x 30 Amicrometre and a highly flexible ribbon cable with a cross section of only 130 Amicrometre x 10 Amicrometre. As flexible insulation materials for the conducting paths to the microelectrodes the biocompatible polymers parylene-C and polyimide were investigated, in which parylene-C revealed as an unsuitable material for this purpose. To guarantee a safe electrical stimulation of neurons, electrode materials with sufficient charge injection capacity have to be used. For this purpose the promising, electrical conductive polymer PEDOT is investigated in the present dissertation, which is deposited on the microelectrodes using an electropolymerization process. In-vitro long-term tests could verify that a degradation of this polymer coating does not occur after short current pulses. Improvements of the polymerization process could furthermore increase the mechanical stability and charge injection capacity of ca. 2 mC/cm2 of this electrode coating. For the implantation of the neural probes an insertion tool was additionally designed and fabricated, which is used to enable a complete and precise insertion of the probe into the cortex. In-vivo experiments could verify the functionality for chronic recording and microstimulation of neural activity using the novel neural probes. Therefore these neural implants have a high potential also for medical applications
Graded Structured Tools for Dry Rotary Swaging
Get PDFNowadays cold forming processes, especially the incremental process rotary swaging, use high amounts of lubricants with disadvantages like costs of recycling, replacement and for cleaning of the workpieces. But the lubricant fulfill necessary functions such as lubricating, flushing and cleaning of the tools. To enable dry forming without lubricant, it is necessary to substitute the functions by means of coating and structuring of the tools. In this study infeed rotary swaging with graded structured tools is investigated by FEM simulations and by experiments. The simulated process forces are in good accordance to the measured ones. Finally, the racticability of dry rotary swaging with graded structured tools is demonstrated
Einfluss von Oberflächenstrukturierungen auf die Stempelkraft beim Vollvorwärtsfließpressen von 16MnCr5
Get PDFDurch rechtliche Bestimmungen sowie aufgrund von ökonomischen und ökologischen Bedenken wird die Reduktion von Schmierstoffen in Umformprozessen angestrebt. Im Schwerpunktprogramm (SPP) 1676 der Deutschen Forschungsgemeinschaft (DFG) widmet man sicher dieser Ausgangssituation mit der Erforschung umweltfreundlicher Tribosysteme in der Umformtechnik. Insbesondere stehen Tribosysteme im Fokus, die keine zusätzlichen Prozessschritte, wie das Aufbringen und Entfernen von Schmierstoffen, benötigen. In Kooperation mit dem Institut für Oberflächentechnik (IOT) der RWTH Aachen University erforscht das Werkzeugmaschinenlabor (WZL) der RWTH Aachen University das Vollvorwärtsfließpressen (VVFP) im Hinblick auf einen trockenen Umformprozess. Werkzeugseitig untersucht das IOT die speziell für das Beanspruchungskollektiv der Kaltmassivumformung hergestellten selbstschmierenden (Cr,Al)N X:S (X = Mo, W) PVD-Beschichtungen. Werkstückseitig untersucht das WZL die Aufbringung unterschiedlicher Oberflächenstrukturierungen, um damit die Reibungszustände gezielt anzupassen und dadurch ein trockenes VVFP zu ermöglichen. Die Wirkmechanismen zwischen strukturierten Halbzeugoberflächen und Werkzeugen, die eine selbstschmierende Beschichtung aufweisen, sind vor allem in Bezug auf Reibung und Verschleiß unbekannt. Das Ziel des Forschungsansatzes ist die Ermittlung einer optimierten Halbzeugstrukturierung unter Verwendung beschichteter Matrizen zur Reduktion der Reibschubspannung beim Fließpressen. Die Versuche wurden durch beschichtete und unbeschichtete Werkzeuge erweitert, um die Reduzierung der Prozesskräfte aufgrund der Beschichtung zu belegen. Die umgeformten Halbzeuge wurden vor und nach dem Pressen durch ihre Geometrie, Oberflächenrauheit und Härte charakterisiert. Ein Fokus lag auf der unterschiedlichen Einebnung der Oberflächenstrukturen. Die Analyse zeigte die optimale Oberflächenstruktur für ein Werkstück in einem geschmiertes Tribosystem im Hinblick auf eine Reduzierung der Prozesskräfte auf. Aus den Ergebnissen lässt sich ein angepasstes Tribosystem für das trockene VVFP ableiten
Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography
No full textPolar ice cores act as a unique archive of the Earth's climate system. However, due to logistic constraints, the representativity of these ice-core records cannot be estimated directly. One possible remedy is to analyze the spatial variability in polar snow and firn and combine the results with an improved understanding of the formation of paleoclimatic ice-core signals and their evolution with depth. Here, X-ray computed tomography is applied as a non-destructive method that yields information on stratigraphy and microstructure in polar snow and firn. The results are used to contribute to both subtopics of this indirect approach for estimating representativity. New methods for sampling the snowpack as well as the detection and alignment of coherent signals in spatially-distributed datasets are presented. They are applied to analyze spatial variability in the snowpack both on the local (trench studies in Greenland and East Antarctica, distances up to 100 m) and the regional scale (450 km traverse through North Greenland). The matching algorithm is validated using randomly generated profiles with the same statistical properties as the original data. Snow and firn density as markers of stratigraphy are determined by two-dimensional radioscopic imaging, the water-isotopic d18O signal is used for age dating. The results show that regionally a significant share of the stratigraphic density signal persists over hundreds of kilometers. Locally, there is a strong directional influence of the wind with a much larger homogeneity of the snowpack along the main wind direction. As density is an important input parameter for remote sensing and surface-mass-balance estimates, representative profiles or mean values of snow and firn density are required. Such a profile is provided for the upper two meters of the North Greenland snowpack. On the local scale, the estimation of representative densities for certain areas of interest (such as the footprint of an altimeter) is complicated by the directional dependence of the stratigraphic variability. As the density layering is significantly impacted by melting of the snow surface, melt features dating to the warm Greenlandic summer of 2012 are analyzed in detail. A large heterogeneity of these features is quantified, which does not only affect remote measurements (where ice layers act as reflectors for electromagnetic waves) but also strongly influences the ability to interpret single-core melt records. Methodological advances in the three-dimensional computed tomography of polar firn allow the creation of a first extensive dataset of direct firn-microstructure measurements. Three ice cores that represent different extremes of the temperature and accumulation ranges are analyzed throughout the lock-in zone, the depth range where pores are sealed from the atmosphere. The fundamental lock-in process is a determining factor for the gas-age-ice-age difference, which can be on the order of several 1,000 years. Thus, accurate estimates of this value are of particular importance for the interpretation of phase relationships between ice and gas records. The dataset is used to show that the critical porosity of pore enclosure is a climate-independent constant, a finding that is corroborated by percolation theory. Incorporation of this result significantly influences the dating of trace-gas records, reducing mismatches with other climate proxies by up to more than 1,000 years. Furthermore, it is demonstrated why previous measurements yielded misleading results
On the dielectrophoretic particle retention in porous media
Get PDFDielectrophoresis (DEP) is a very suitable particle manipulation technique that is able to solve a range of separation problems because it is label-free, very sensitive and, if applied correctly, highly selective towards a specific target particle. DEP has mostly been researched and applied (bio-)analytical chemistry to solve separation problems on lab-on-a-chip devices at uL/min throughputs, which makes it incompatible for industrial scale processes. This thesis investigates a high-throughput method, DEP filtration, which is particle retention due to DEP in porous media. Particle retention dynamics in model porous media are scrutinized using simulative and experimental methods. Particle movement in transparent microchannels gives first-hand insight into DEP trapping dynamics. The results presented pave the way toward actual high-throughput DEP filtration that could tackle important separation problems, such as the separation of metal from scrap in recycling
Role of Mixed Layer Depth and Subduction Processes for the Southern Ocean Carbon and Nutrient Cycles
Get PDFChanges in wind forcing in the Southern Ocean exert a large impact on the dynamics of the surface mixed layer and subduction processes. Over the last two decades, the index of the Southern Annular Mode (SAM) has experienced a trend towards its positive phase, which is characterized by stronger westerly winds. The positive trend in the SAM index results from the complex interaction between the steady increase of atmospheric CO2 concentration due to anthropogenic emissions and the stratospheric ozone depletion. Co-occurring with the wind signal is the global warming effect driven by the increase in atmospheric CO2. Increased wind forcing alone would lead to a deepening of the mixed layer and enhance the supply of carbon and nutrients to the euphotic zone. In contrast, the surface ocean warming alone would lead to more surface stratification, and therefore to a shoaling of the mixed layer. The main objective of this PhD thesis is to answer the question: How did the combined changes in atmospheric forcing affect the surface mixed layer and the carbon and nutrient subduction rates on the timescale of interannual to decadal variability? In the first part of my thesis, I assessed the impact of the recent changes in atmospheric temperature and zonal wind speed on the summer mixed-layer depth (MLD) in the SO (south of 30AAA S) from observations and a set of model sensitivity experiments over the period of 2002-2011. The study showed that summer MLD changes in response to recent atmospheric forcing were zonally asymmetric. Summer MLD increased in the Antarctic Zone of the Atlantic and the Indian Ocean sectors. Overall, the effect of recent changes in wind forcing dominated over temperature-induced changes in summer MLD. In the second part of this thesis, I examined the decadal variability in nutrient and dissolved inorganic carbon (DIC) concentrations in the Antarctic Intermediate Water of the Atlantic sector of the Southern Ocean between 1990 and 2014 using cruise data sampled along the Prime Meridian. The results showed a positive trend in DIC and nitrate concentrations along with a negative trend in temperature and salinity. These observations support a scenario of an increase in the upper-ocean overturning circulation probably linked to the positive trend in the SAM index. The third part of this thesis focused on the SAM impact on the inter-annual variability of carbon and nutrient subduction rates across the base of the winter mixed layer between 1958 and 2016 using a coupled physical-biogeochemical general circulation model. The study showed that the variations in SAM led to large-scale anomalies in carbon and nutrient subduction and obduction rates that are zonally symmetric. More obduction occured south of the Antarctic Polar Front (APF) and more subduction occurred where the MLD gradient is strongest in response to the positive trend in the SAM index. Also, I found that the annual mean carbon and nutrient subduction rates varied by around 10% around the long-term mean on interannual to decadal time scales with a stronger positive trend since 1990 leading to an approximately 20% increase in DIC and nitrate subduction rates between 1990 and 2016. My findings (parts I, II and III) suggest that the positive trend of the SAM index (wind intensification) has profoundly affected the surface mixed layer, and increased upwelling of carbon and nutrient-rich deep water. The increased upwelling is driven by the Ekman divergence and is balanced by the stronger northward Ekman transport across the APF. North of the APF these water masses subduct as mode and intermediate waters. While today changes in the wind forcing play a larger role than atmospheric temperature changes, this might reverse in the future
Sozialepidemiologische, versorgungsbezogene und forschungsmethodische Aspekte der intrauterinen Wachstumsverzögerung (IUGR) des Fetus
Get PDFFetal growth monitoring and an early antenatal detection of intrauterine growth restriction (IUGR) is of core importance in routine antenatal care. IUGR is associated with a higher risk for perinatal morbidity and mortality, and an elevated risk for chronic conditions later in life. Under routine conditions, low antenatal detection rates of 25 - 30 % were observed and there is a lack of a clearly defined terminology and definition of IUGR. Women with migrant background and low socioeconomic status may be specific groups having a higher chance of antenatal non-detection of IUGR. The primary objective of this dissertation is the examination of the routine antenatal care of women with pregnancies affected by suboptimal fetal growth, particularly with respect to health inequity and research-methodological aspects. Primary data of the project, entitled Care-related factors associated with antenatal diagnosis of intrauterine growth restrictions (IUGR) a a case-control study was used for this dissertation. The project had two components: (1) hospital-based case-control study with mothers of newborns with a birthweight 10th percentile and (2) a physician survey among gynecologists in Bremen and Lower Saxony. In our study suboptimal fetal growth was antenatally identified in less than half (47.8 %) of the cases as determined perinatally. A lesser degree of severity of IUGR, the absence of maternal complications / diseases during pregnancy, and no Doppler examination during the course of pregnancy were associated with a higher chance of antenatal non-detection of IUGR. Although not statistically significant, we found that antenatal non-detection of IUGR was about two times more likely in women with migration background (OR 1.8; 95 %a KI: 0.68, 4.56) as compared to non-migrants. The physician survey among primary care gynecologists indicates considerable variation in antenatal detection and management of (suspected) IUGR, e.g. in the use of cut-off values to classify a fetus as SGA. The results of these investigations indicate that there is a substantial potential for improvement in routine antenatal care in Germany. Better antenatal detection of IUGR may be aided by the establishment and implementation of a standardized terminology and definition of IUGR and (to the extent possible) the determination of an evidence-based management of (suspected) suboptimal fetal growth. One conceivable option is the implementation of a mandatory Doppler examination shortly before birth, in general or at least for some subgroups (e.g. women with migration background). Further research (with lager study populations) is needed to examine whether women with migration background or low socioeconomic status have a higher chance of antenatal non-detection of IUGR and to further investigate possible causal factors
Friedrich Walburg - Ein bremischer Lehrer und Archäologe zwischen demokratischer Schulreform und nationalsozialistischer Kulturpolitik
Get PDFFriedrich Walburg erlangte ab 1919 als Vorsitzender der Arbeitsgemeinschaft für Geschichtsunterricht des Bremischen Lehrervereins und Herausgeber der Schulbuchreihe Geschichtsunterricht im neuen Geiste Bekanntheit. Trotz seiner Nähe zur sozialdemokratisch geprägten Schulreformbewegung in Bremen konnte er sich im Nationalsozialismus weiterhin erfolgreich als Pädagoge einbringen und erweiterte sein Tätigkeitsfeld um die prähistorische Archäologie. Die Integration in nationalsozialistische Forschungsstrukturen behinderte seinen beruflichen Werdegang nach 1945 kaum. Der Aufsatz stellt erstmals Walburgs wissenschaftliche und pädagogische Tätigkeiten überblicksartig zusammen
Assessing the State and Impacts of the Artisanal Reef Fisheries and their Management Implications in Kenyan South Coast
Get PDFArtisanal fisheries of tropical waters are estimated to harvest about 25% of the world s fisheries catch. Despite this importance, a majority of tropical fish stocks remain unassessed and poorly managed. Reasons include a severe under-reporting of catches or the lack of reliable information of the fishery. With the growing concern over overexploitation and the challenge to assess fisheries status in these data-limited situations, a suit of assessment approaches have been proposed. In this study, we explore the usefulness of these data-limited approaches for the multi-species and multi-gear fishery of the Kenyan coast. The primary objective was to evaluate the current level and impacts of the fishery at the species and ecosystem level and to revise current management measures. In a first step, we used the Schaefer and Fox production models to estimate the sustainable catch and effort limits of the pooled catches for the entire coastal fishery and also explored possible changes in the mean trophic level of the catch by analysing officially reported time series data over sixty years. The results indicate that the current fish extraction and effort surpass sustainable limits (MSY) and that the mean trophic level of the catch has continuously declined over the years. In a second step, the size structure of currently obtained catches from the multi-gear fishery was studied based on a case study area of the Kenyan South coast. Results reveal that the multi-species fisheriesa catches are dominated by small to medium-sized species and individuals. While these finding may indicate an unsustainable fishery, where older and larger fish have been serially depleted from the stock leading to a truncation of the size structure of the aggregated catches and a critical removal of large spawners, it is also possible that the observed pattern has emerged because of a fishers shift towards the smaller, more abundant and productive elements of the fished community. In this context, it is important to mention that catches from different gears overlap in species and sizes but also differ due to gear selectivity and spatial differences in gear use (inshore shallow lagoon versus more offshore waters). In a third step, the exploitation rates of the four commercially most important target species of the fishery were determined using lengtha based single-species stock assessment approaches. Results suggest moderate to high mean exploitation rates for all species with low spawning potential ratios, supporting the results of the above analysis of an unsustainable fishery, with some species experiencing both growth and recruitment overfishing. In a fourth step, results from the single-species stock assessment were compared to those obtained from a holistic trophic model constructed for the study area. The results from the latter suggest that the system is in a perturbed (immature) state, likely due to the very intense resource exploitation. Overall catch volumes are relatively low (4.6 t Km-2 year-1), and comparable to other intensively exploited coastal and coral reef ecosystems of the world. Our findings reveal that it may not be sufficient to rely on the current single-species management approaches such as gear restrictions and size limits for sustaining this multi-species fishery. Instead, control and reduction of the fishing effort and the establishment of specific areas closed to some fisheries may be needed if sustainable, ecosystem-based management is to be achieved. This should be done while considering the fishing impacts, the economic and social benefits within the ecosystem context