12,122 research outputs found
Zoocoenological state of microhabitats and its seasonal dynamics in an aquatic macroinvertebrate assembly (Hydrobiological case studies on lake Balaton, No. 1.)
In the years 2002, 2003 and 2004 we collected samples of macroinvertebrates on a total of 36
occasions in Badacsony bay, in areas of open water (in the years 2003 and 2004 reed-grassy) as well as
populated by reed (Phragmites australis) and cattail (Typha angustifolia). Samples were taken using a stiff
hand net. The sampling site includes three microhabitats differentiated only by the aquatic plants inhabiting
these areas. Our data was gathered from processing 208 individual samples. The quantity of
macroinvertebrates is represented by biovolume value based on volume estimates. We can identify taxa in
abundant numbers found in all water types and ooze; as well as groups associated with individual microhabitats
with various aquatic plants. We can observe a notable difference between the years in the volume of
invertebrate macrofauna caused by the drop of water level, and the multiplication of submerged macrophytes.
There are smaller differences between the samples taken in reeds and cattail stands. In the second
half of 2003 â which was a year of drought â the Najas marina appeared in open waters and allowed to
support larger quantities of macroinvertebrates. In 2004 with higher water levels, the Potamogeton perfoliatus
occurring in the same area has had an even more significant effect. This type of reed-grass may support
the most macroinvertebrates during the summer. From the aspect of diversity relations we may suspect
different characteristics. The reeds sampling site proved to be the richest, while the cattail microhabitat is
close behind, open water (with submerged macrophytes) is the least diverse microhabitat
Why do commercial companies contribute to open source software?
This is the post-print version of the Article. The official published version can be accessed from the link belowMany researchers have pointed out that the opensource movement is an interesting phenomenon that is difficult to explain with conventional economic theories. However, while there is no shortage on research on individualsâ motivation for contributing to opensource, few have investigated the commercial companiesâ motivations for doing the same. A case study was conducted at three different companies from the IT service industry, to investigate three possible drivers: sale of complimentary services, innovation and open sourcing (outsourcing). We offer three conclusions. First, we identified three main drivers for contributing to opensource, which are (a) selling complimentary services, (b) building greater innovative capability and (c) cost reduction through open sourcing to an external community. Second, while previous research has documented that the most important driver is selling complimentary services, we found that this picture is too simple. Our evidence points to a broader set of motivations, in the sense that all our cases exhibit combinations of the three drivers. Finally, our findings suggest that there might be a shift in how commercial companies view opensource software. The companies interviewed have all expressed a moral obligation to contribute to open source
Shocks in coupled socio-ecological systems: what are they and how can we model them?
Coupled socio-ecological systems (SES) are complex systems characterized by self-organization, non-linearities, interactions among heterogeneous elements within each subsystem, and feedbacks across scales and among subsystems. When such a system experiences a shock or a crisis, the consequences are difficult to predict. In this paper we first define what a shock or a crisis means for SES. Depending on where the system boundary is drawn, shocks can be seen as exogenous or endogenous. For example, human intervention in environmental systems could be seen as exogenous, but endogenous in a socio-environmental system. This difference in the origin and nature of shocks has certain consequences for coupled SES and for policies to ameliorate negative consequences of shocks. Having defined shocks, the paper then focuses on modelling challenges when studying shocks in coupled SES. If we are to explore, study and predict the responses of coupled SES to shocks, the models used need to be able to accommodate (exogenous) or produce (endogenous) a shock event. Various modelling choices need to be made. Specifically, the âsuddenâ aspect of a shock suggests the time period over which an event claimed to be a shock occurred might be âquickâ. What does that mean for a discrete event model? Turning to magnitude, what degree of change (in a variable or set of variables) is required for the event to be considered a shock? The âsurprisingâ nature of a shock means that none of the agents in the model should expect the shock to happen, but may need rules enabling them to generate behaviour in exceptional circumstances. This requires a certain design of the agentsâ decision-making algorithms, their perception of a shock, memory of past events and formation of expectations, and the information available to them during the time the shock occurred
Archiving Software Surrogates on the Web for Future Reference
Software has long been established as an essential aspect of the scientific
process in mathematics and other disciplines. However, reliably referencing
software in scientific publications is still challenging for various reasons. A
crucial factor is that software dynamics with temporal versions or states are
difficult to capture over time. We propose to archive and reference surrogates
instead, which can be found on the Web and reflect the actual software to a
remarkable extent. Our study shows that about a half of the webpages of
software are already archived with almost all of them including some kind of
documentation.Comment: TPDL 2016, Hannover, German
A modeling framework to assess water and nitrate balances in the Western Bug river basin, Ukraine
The objective of this study was to assess the utility of the
eco-hydrological SWAT model (Soil and Water Assessment Tool, Arnold et al.,
1998) for representing water balance and nitrate fluxes given limited input
and calibration data. The investigated catchment is located in Western
Ukraine with an area of approximately 2616 km<sup>2</sup>. Land use is currently
dominated by agriculture with significant areas of pasture, and has
undergone a high degree of changes in land-use and agricultural practice
since the end of the Soviet Union. Model application produced a fitted water
balance (calibration: <i>R</i><sup>2</sup> = 0.52, NS = 0.46; validation: <i>R</i><sup>2</sup> = 0.47,
NS = 0.51) and plausible ranges and dynamics of nitrate in stream loadings.
Groundwater parameters were found to be highly sensitive. The results
indicate that SWAT is an appropriate tool for water resource investigations
in the Western Bug catchment, and can provide a useful tool for further
eco-hydrologic research in the region (i.e. diffuse pollution impacts)
Libxc: a library of exchange and correlation functionals for density functional theory
The central quantity of density functional theory is the so-called
exchange-correlation functional. This quantity encompasses all non-trivial
many-body effects of the ground-state and has to be approximated in any
practical application of the theory. For the past 50 years, hundreds of such
approximations have appeared, with many successfully persisting in the
electronic structure community and literature. Here, we present a library that
contains routines to evaluate many of these functionals (around 180) and their
derivatives.Comment: 15 page
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Proceedings ICPW'07: 2nd International Conference on the Pragmatic Web, 22-23 Oct. 2007, Tilburg: NL
Proceedings ICPW'07: 2nd International Conference on the Pragmatic Web, 22-23 Oct. 2007, Tilburg: N
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