Ordovician reef and mound evolution : the Baltoscandian picture

The widespread growth of reefs formed by a framework of biogenic constructors and frame-lacking carbonate mounds began on Baltica during Ordovician time. Previously, Ordovician reef and mound development on Baltica was considered to be sporadic and local. A review of all known bioherm localities across the Baltic Basin reveals a more consistent pattern. Ordovician bioherms grew in a wide E-W-aligned belt across the Baltic Basin and occur in several places in Norway. Substantial reef development began simultaneously across the region during the late Sandbian - early Katian interval and climaxed during the late Katian Pirgu age. The current spatiotemporal distribution of bioherms is a result of interdependent factors that involve original drivers of reef development such as relative sea level, climate during the time of deposition and effects of post-depositional erosion. Oceanographic conditions were likely more favourable during times of cooler global climates, low sea level and glacial episodes. At the same time, the likelihood that bioherms are preserved from long-term erosion is higher when deposited during low sea level in deeper parts of the basin. A main factor controlling the timing of the reef and mound evolution was Baltica's shift toward palaeotropical latitudes during Late Ordovician time. The time equivalence between initial reef growth and the Guttenberg isotope carbon excursion (GICE) suggests that global climatic conditions were important.Peer reviewe

Comparison of a solid oxide cell with nickel/gadolinium‐doped ceria fuel electrode during operation with hydrogen/steam and carbon monoxide/carbon dioxide

Solid oxide cells (SOCs) offer the possibility to operate on hydrogen/steam (H$_2$/H$_2$O), carbon monoxide/carbon dioxide (CO/CO$_2$), and mixtures thereof in the fuel cell as well as in the electrolyzer mode. In this study, the electrochemical processes in an electrolyte-supported SOC exhibiting a La$_w$ Sr$_x$ Co$_y$ Fe$_z$ O$_{(3-δ)}$ air electrode and a nickel/gadolinium-doped ceria (Ni/CGO) fuel electrode (FE) were analyzed by electrochemical impedance spectroscopy, and the subsequent impedance data analysis by the distribution of relaxation times for CO/CO$_2$ fuel mixtures. A physicochemical equivalent circuit model was fitted to the measured spectra. With the help of the extracted parameters, a zero-dimensional direct current cell model was parametrized to simulate the current-voltage behavior of the cell. This approach, previously implemented for H$_2$/H$_2$O fuel mixtures, is extended toward CO/CO$_2$ fuels. It will be shown that the same model – with adapted parameters for the FE – can be applied. A comparison of measured and simulated current-voltage curves showed an excellent agreement for both fuels and operating modes (solid oxide fuel cell/solid oxide electrolyzer cell). Simulations reveal that there is nearly no performance difference between H$_2$O and CO$_2$ electrolysis for the electrolyte-supported cell with Ni/CGO FE in comparison to an anode-supported cell with Ni/yttria-stabilized zirconia FE

Ordovician climate changes in the northern subtropics: The δ18O record from the Tunguska Basin, Siberia

Oxygen isotopes from bioapatite (conodonts) have been used for several decades to reconstruct the Palaeozoic climate history. During the Ordovician, conodont-based δ18Ophos studies have revealed a general cooling trend throughout the system. The δ18Ophos data from Estonia confirm this long-term shift but also demonstrate that against the background of a generally cooling climate in the pre-Hirnantian, the Late Ordovician was quite unstable, with several episodes of sea surface temperature (SST) decrease and increase of different magnitude and duration. In the sedimentary sequence, these cooling events are reflected by major sea-level lowstands. Several of these are also recognizable in the Tunguska Basin of Siberia. We have recently studied the δ18Ophos record from two Middle and Upper Ordovician sections in Siberia. Comparisons of the results with data from the Baltic region have revealed differences but also some similarities in the δ18Ophos trends, even though these two regions were located on different palaeocontinents, Siberia and Baltica. Both were geographically separated and display different Early Palaeozoic histories with respect to their environmental conditions. Siberia was located in low equatorial latitudes from the Cambrian onwards and remained there through the Ordovician and Silurian, whereas Baltica drifted from high southern latitudes to low latitudes from the late Cambrian and reached the southern subtropics in the Late Ordovician (late Sandbianâearly Katian). Despite Siberiaâs location at low northern subequatorial latitudes, the upper Middle (starting from the Darriwilian) and the Upper Ordovician in the Tunguska Basin are assumed to be represented by cool-water deposits (various calcareous siltstones with interbeds of micritic and/or bioclastic limestone). The onset of cool-water conditions is explained by plate-tectonic reorganization, resulting in the upwelling of cold oceanic waters along the southern margin of the palaeocontinent and their penetration into the epicontinental seas. Our δ18Ophos data generally fluctuate around 17.5â° (VSMOW), indicating that SST was relatively stable. This general state is interrupted by six cooling episodes, but unlike in Baltica, no general trend of SST change in any direction (decrease or increase) is evident. In the Baltic region, a general cooling trend prevailed, and SST decreased continuously during the pre-Hirnantian Late Ordovician. In addition to this general trend, seven cooling events (CE) are observed, named (from the oldest upwards) the Late Kukruse, Haljala, Keila, Early Nabala, Vormsi, Early Pirgu, and Middle Pirgu CEs. Comparison of the δ18Ophos curves from the Tunguska and Baltoscandian basins shows that five of these CEs are reflected by brief intervals of higher δ18Ophos values also in the former one. The Keila CE is identified in the lower Mangazea Formation (Fm), the Early Nabala CE in the upper Mangazea Fm, and the Vormsi CE in the uppermost Mangazea Fm. In addition, the Haljala CE probably corresponds to an interval in the lowermost Mangazea Fm and the Early Pirgu CE to a small δ18Ophos peak in the lowermost Dolbor Fm. The most pronounced CE in Siberia is recorded in the upper Darriwilian, in the lower UstâStolbovaya Fm, and apparently reflects the Middle-Darriwilian Ice Age. The recognition of the same CEs in successions on two different palaeocontinents is clear evidence that they are not some regional phenomena but the result of global climatic perturbations. The recently acquired δ18Ophos data allow an improvement in the dating of the Siberian strata and their correlation with successions on other palaeocontinents. Previously, the MDICE, Upper Kukruse Low, GICE, and an interval probably including Rakvere (KOPE) and Saunja carbon isotopic events (CIE) were recognized in the Siberian δ13Ccarb record. Now, the position of the Keila CE just below an increase in δ13Ccarb in the Tunguska Basin confirms the identification of this CIE as GICE and allows the correlation of this level (lower Baksian Regional Stage) with the Keila Regional Stage in Estonia. In addition, the prolonged CIE between the Early Nabala and Vormsi CEs as identified in the Tunguska Basin apparently corresponds to the Saunja (Waynesville) CIE. This also means that the small peak in the δ13Ccarb curve below this CIE correlates with the Rakvere CIE

Wind farm facilities in Germany kill noctule bats from near and far

Over recent years, it became widely accepted that alternative, renewable energy may come at some risk for wildlife, for example, when wind turbines cause large numbers of bat fatalities. To better assess likely populations effects of wind turbine related wildlife fatalities, we studied the geographical origin of the most common bat species found dead below German wind turbines, the noctule bat (Nyctalus noctula). We measured stable isotope ratios of non-exchangeable hydrogen in fur keratin to separate migrants from local individuals, used a linear mixed-effects model to identify temporal, spatial and biological factors explaining the variance in measured stable isotope ratios and determined the geographical breeding provenance of killed migrants using isoscape origin models. We found that 72% of noctule bat casualties (n = 136) were of local origin, while 28% were long-distance migrants. These findings highlight that bat fatalities at German wind turbines may affect both local and distant populations. Our results indicated a sex and age-specific vulnerability of bats towards lethal accidents at turbines, i.e. a relatively high proportion of killed females were recorded among migratory individuals, whereas more juveniles than adults were recorded among killed bats of local origin. Migratory noctule bats were found to originate from distant populations in the Northeastern parts of Europe. The large catchment areas of German wind turbines and high vulnerability of female and juvenile noctule bats call for immediate action to reduce the negative cross-boundary effects of bat fatalities at wind turbines on local and distant populations. Further, our study highlights the importance of implementing effective mitigation measures and developing species and scale-specific conservation approaches on both national and international levels to protect source populations of bats. The efficacy of local compensatory measures appears doubtful, at least for migrant noctule bats, considering the large geographical catchment areas of German wind turbines for this species

Multigenerational outbreeding effects in Chinook salmon (Oncorhynchus tshawytscha)

Outbreeding, mating between genetically divergent individuals, may result in negative fitness consequences for offspring via outbreeding depression. Outbreeding effects are of notable concern in salmonid research as outbreeding can have major implications for salmon aquaculture and conservation management. We therefore quantified outbreeding effects in two generations (F1 hybrids and F2 backcrossed hybrids) of Chinook salmon (Oncorhynchus tshawytscha) derived from captively-reared purebred lines that had been selectively bred for differential performance based on disease resistance and growth rate. Parental lines were crossed in 2009 to create purebred and reciprocal hybrid crosses (n = 53 families), and in 2010 parental and hybrid crosses were crossed to create purebred and backcrossed hybrid crosses (n = 66 families). Although we found significant genetic divergence between the parental lines (FST = 0.130), reciprocal F1 hybrids showed no evidence of outbreeding depression (hybrid breakdown) or favorable heterosis for weight, length, condition or survival. The F2 backcrossed hybrids showed no outbreeding depression for a suite of fitness related traits measured from egg to sexually mature adult life stages. Our study contributes to the current knowledge of outbreeding effects in salmonids and supports the need for more research to better comprehend the mechanisms driving outbreeding depression. © 2014 Springer International Publishing Switzerland

Concerns of Ageing and Interest in Assistive Technologies – Convenience Sampling of Attendees at an Aged Care Technology Exhibition in China

Part 7: e-Health, the New Frontier of Service Science InnovationInternational audienceAs in many countries, ageing and aged care in China is an important issue. There is a need for more research on the potential for technology to assist older people and their families, particularly given the disappointing levels of adoption in developed countries. Accordingly this paper aims to gain insight into the perceptions of older people and stakeholders in relation to issues of ageing and their interest in adoption of technology. Using convenience sampling, the authors surveyed 277 participants to understand peoples concerns concerning ageing and use of technologies. Results from this study provide a basis for discussion with stakeholders, particularly concerning ageing in China

Performance analysis on percentage of wheel slip for a passenger car using GPS and wheel speed sensor

This thesis deals with the analysis on percentage of wheel slip for a passenger car using GPS and wheel speed sensor. The objective of this thesis is to analyze the percentage of wheel slip for a passenger car in a various velocity, road condition and driving mode. The thesis describes the post-processing method to analyze the percentage of wheel slip and identify the effective rolling radius and the longitudinal tire stiffness for maximum tire life and performance. Driving and braking behaviour of vehicle were both studied in this thesis for paved and unpaved sandy road condition which commonly the contributing factors to the wheel slip to occur. The data used for the analysis is obtained through experimental test using UMP Test Car which has been installed with Wheel Pulse Transducer, Global Positioning System and DEWESOFT software for data acquisition purpose. The post-processing method was performed using Flexpro and Microsoft Office Excel. The post-processing method to analyze the percentage of wheel slip was performed using the SAE definition of wheel slip and the percent error in the distance travel by the car between free rolling and actual condition. Finally, the longitudinal force, the effective rolling radius and the longitudinal tire stiffness was determined for both driving and braking maneuver of vehicle on paved and unpaved sandy road condition. From the results, it is observed that the percentage of wheel slip during driving maneuver is higher for unpaved sandy road condition compares to that the paved road. It is also observed that the longitudinal force of the tire is lower for unpaved sandy road compare to the paved road condition. The effective rolling radius of the tire during driving maneuver was determined to be lower compare to the free rolling radius of the tire. During braking manuever, the results show that the percentage of wheel slip is higher for unpaved sandy road compare to that for paved road condition. The longitudinal force and tire stiffness also observed lower for unpaved sandy road condition. The effective rolling radius of the tire during braking determined higher compared to that in the free rolling radius. The results concluded that the percentage of wheel slip is strongly dependent to the longitudinal force and the tire road friction. Therefore, effective rolling radius and longitudinal tire stiffness obtained can significantly use to improve tire design and construction. The results also can be use to improve the energy usage efficiency and fuel consumption of vehicle

Changes in shelf phosphorus burial during the Hirnantian glaciation and its implications

The Late Ordovician mass extinction occurred during an icehouse interval, accompanied by the glaciation of the supercontinent Gondwana, which was located at the South Pole at that time. As suggested by sequence stratigraphy of near- and far-field sedimentary successions as well as stable oxygen isotope studies, ice sheets reached their maximum extent in the late Hirnantian M. persculptus graptolite zone. As a result, the global sea-level dropped significantly during the Hirnantian Glacial Maximum (HGM). This led to exposure and erosion of sediments on the tropical shelves of Laurentia and Baltica. Where shelves remained submerged, water depths were probably very shallow. Local redox proxies, such as I/Ca ratios or iron speciation, indicate that shelf environments were well oxygenated. At the same time, stable uranium isotopes, measured on shallow-water carbonate samples, indicate a global expansion of the seafloor overlain by anoxic water. This implies that the observed increase in anoxia was confined to the open ocean and that there was a redox gradient between coastal and oceanic environments. Unfortunately, the lack of Late Ordovician deep water sedimentary records makes it impossible to directly measure open-ocean redox conditions. In general, Late Ordovician deoxygenation is in stark contrast to other oceanic anoxic events of the Phanerozoic, which occurred during greenhouse conditions and are associated with rising water temperatures. Under present interglacial conditions, with a relatively high sea-level, it is estimated that about 70% of the nutrient phosphorus delivered from the continents is retained in shelf sediments. Hence, shelf environments act as a nutrient filter. However, during times of low sea-level, this filter is switched off due to the bypassing of incoming riverine dissolved load through river canyons. As a result, excess phosphorus is released into the open ocean leading to eutrophication. This has previously been proposed for the Last Glacial Maximum (LGM) and is supported by geochemical data. We suggest that this scenario may also be applicable to the HGM and serve as an explanation for increasing anoxia during cold climatic conditions. To test this, we measured phosphorus concentrations across the HGM on carbonate samples collected from two low-latitude successions (Ruisseau aux Algues on Anticosti Island and Valga-10 core section from Estonia, both interpreted as shelf environments). To eliminate the detrital, non-reactive phosphorus fraction, we used the SEDEX sequential extraction method, which allows to separately measure reactive (Preact) and organic phosphorus (Porg). In order to evaluate the burial efficiency of phosphorus, we determined total organic carbon (C) concentration and calculated C/Porg and C/Preact ratios. We observe a decreasing trend in Preact towards the HGM and a minimum during the subsequent initial transgression. Low C/Preact and C/Porg in the range of the Redfield ratio indicate efficient burial under oxygenated conditions. Therefore, we can rule out that phosphorus regeneration, which is stronger under anoxic conditions, caused the observed minimum. This means that Preact is a direct measure of primary productivity and phosphorus burial. Using the Preact data and an estimate for the shelf area, we modelled the global burial flux of phosphorus into shelf sediments. Due to the overall reduction in shelf area during the HGM and the low Preact contents, the modelling suggests that the shelf burial flux was approximately halved. If the phosphorus input had remained constant across the interval, which is reasonable given that the erosion of exposed shelf sediments compensated for a reduction in continental weathering during the cold and arid climate, the excess phosphorus would have entered the open ocean stimulating primary productivity. Ultimately, enhanced productivity would have resulted in a high organic matter sinking flux and oxygen depletion by aerobic respiration. In summary, our data and modelling support the proposed scenario of an inefficient nutrient filter