The Effect of Use and Access on Citations

It has been shown (S. Lawrence, 2001, Nature, 411, 521) that journal articles which have been posted without charge on the internet are more heavily cited than those which have not been. Using data from the NASA Astrophysics Data System (ads.harvard.edu) and from the ArXiv e-print archive at Cornell University (arXiv.org) we examine the causes of this effect.Comment: Accepted for publication in Information Processing & Management, special issue on scientometric

Satellite Observations of Antarctic Sea Ice Thickness and Volume

We utilize satellite laser altimetry data from ICESat combined with passive microwave measurements to analyze basin-wide changes in Antarctic sea ice thickness and volume over a 5 year period from 2003-2008. Sea ice thickness exhibits a small negative trend while area increases in the summer and fall balanced losses in thickness leading to small overall volume changes. Using a five year time-series, we show that only small ice thickness changes of less than -0.03 m/yr and volume changes of -266 cu km/yr and 160 cu km/yr occurred for the spring and summer periods, respectively. The calculated thickness and volume trends are small compared to the observational time period and interannual variability which masks the determination of long-term trend or cyclical variability in the sea ice cover. These results are in stark contrast to the much greater observed losses in Arctic sea ice volume and illustrate the different hemispheric changes of the polar sea ice covers in recent years

Improving Our Understanding of Antarctic Sea Ice with NASA's Operation IceBridge and the Upcoming ICESat-2 Mission

Antarctic sea ice is a crucial component of the global climate system. Rapid sea ice production regimes around Antarctica feed the lower branch of the Southern Ocean overturning circulation through intense brine rejection and the formation of Antarctic Bottom Water (e.g., Orsi et al. 1999; Jacobs 2004), while the northward transport and subsequent melt of Antarctic sea ice drives the upper branch of the overturning circulation through freshwater input (Abernathy et al. 2016). Wind-driven trends in Antarctic sea ice (Holland Kwok 2012) have likely increased the transport of freshwater away from the Antarctic coastline, significantly altering the salinity distribution of the Southern Ocean (Haumann et al. 2016). Conversely, weaker sea ice production and the lack of shelf water formation over the Amundsen and Bellingshausen shelf seas promote intrusion of warm Circumpolar Deep Water onto the continental shelf and the ocean-driven melting of several ice shelves fringing the West Antarctic Ice Sheet (e.g., Jacobs et al. 2011; Pritchard et al. 2012; Dutrieux et al. 2014). Sea ice conditions around Antarctica are also increasingly considered an important factor impacting local atmospheric conditions and the surface melting of Antarctic ice shelves (e.g., Scambos et al. 2017). Sea ice formation around Antarctica is responsive to the strong regional variability in atmospheric forcing present around Antarctica, driving this bimodal variability in the behavior and properties of the underlying shelf seas (e.g., Petty et al. 2012; Petty et al. 2014)

Development of an Applied Field Magnetoplasmadynamic Thruster Design Supported by Numerical Simulations at IRS

In this paper an overview is given on a numerical simulation program for applied field magnetoplasmadynamic thrusters which is currently under development at the Institute of Space Systems (IRS). The simulation code for argon plasma flows in thermal and chemical non-equilibrium uses an axisymmetric finite volume scheme on unstructured, adaptive meshes. The external magnetic field is taken into account employing the vector potential formulation. Azimuthal velocity and magnetic field are handled by a quasi-three dimensional approach with vanishing azimuthal derivatives. Besides the numerical analysis, a radiation-cooled laboratory model of an applied field magnetoplasmadynamic thruster is under development at IRS. The modular design allows adjustments of the thruster to find an optimized thruster geometry based on numerical and experimental results

Skillful spring forecasts of September Arctic sea ice extent using passive microwave sea ice observations

In this study, we demonstrate skillful spring forecasts of detrended September Arctic sea ice extent using passive microwave observations of sea ice concentration (SIC) and melt onset (MO). We compare these to forecasts produced using data from a sophisticated melt pond model, and find similar to higher skill values, where the forecast skill is calculated relative to linear trend persistence. The MO forecasts shows the highest skill in March–May, while the SIC forecasts produce the highest skill in June–August, especially when the forecasts are evaluated over recent years (since 2008). The high MO forecast skill in early spring appears to be driven primarily by the presence and timing of open water anomalies, while the high SIC forecast skill appears to be driven by both open water and surface melt processes. Spatial maps of detrended anomalies highlight the drivers of the different forecasts, and enable us to understand regions of predictive importance. Correctly capturing sea ice state anomalies, along with changes in open water coverage appear to be key processes in skillfully forecasting summer Arctic sea ice

Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic

Effects of Olive Mill Wastewater on Soil Microarthropods and Soil Chemistry in Two Different Cultivation Scenarios in Israel and Palestinian Territories

Although olive mill wastewater (OMW) is often applied onto soil and is known to be phytotoxic, its impact on soil fauna is still unknown. The objective of this study was to investigate how OMW spreading in olive orchards affects Oribatida and Collembola communities, physicochemical soil properties and their interdependency. For this, we treated plots in two study sites (Gilat, Bait Reema) with OMW. Among others, the sites differed in irrigation practice, soil type and climate. We observed that soil acidity and water repellency developed to a lower extent in Gilat than in Bait Reema. This may be explained by irrigation-induced dilution and leaching of OMW compounds in Gilat. In Bait Reema, OMW application suppressed emergence of Oribatida and induced a community shift, but the abundance of Collembola increased in OMW and water-treated plots. In Gilat, Oribatida abundance increased after OMW application. The effects of OMW application on soil biota result from an interaction between stimulation of biological activity and suppression of sensitive species by toxic compounds. Environmental and management conditions are relevant for the degree and persistence of the effects. Moreover, this study underlines the need for detailed research on the ecotoxicological effects of OMW at different application rates

The Reference System in the Model of PGE: Proposing a Generalized Description of Reference Products and their Interrelations

Samsung recently introduced a new smartphone display with increased breaking resistance, which will probably be relevant for future cars as well. This example shows that subsystems, in general artefacts from former development processes can be relevant for subsequent projects. Their integration has to be planned, i.a. even before the original product is in the market and across branches. The research on supporting methods requires a suitable description model for this phenomenon. Research in design reuse and PGE – product generation engineering addresses this only partially yet. Design reuse focuses on the informational aspect, PGE refers primarily to reference products. This contribution aims at closing this gap as a basis for future research. Two case studies from industry projects by the authors and an example from foresight and product planning show the role of artefacts from former development processes in running projects. It is described which artefacts are used as a reference, why they are used and when. Based on these findings the authors propose the term “reference system” to depict the whole set of artefacts, which serves as a basis for every product development project