Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems

Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities

Community Detection via Semi-Synchronous Label Propagation Algorithms

A recently introduced novel community detection strategy is based on a label propagation algorithm (LPA) which uses the diffusion of information in the network to identify communities. Studies of LPAs showed that the strategy is effective in finding a good community structure. Label propagation step can be performed in parallel on all nodes (synchronous model) or sequentially (asynchronous model); both models present some drawback, e.g., algorithm termination is nor granted in the first case, performances can be worst in the second case. In this paper, we present a semi-synchronous version of LPA which aims to combine the advantages of both synchronous and asynchronous models. We prove that our models always converge to a stable labeling. Moreover, we experimentally investigate the effectiveness of the proposed strategy comparing its performance with the asynchronous model both in terms of quality, efficiency and stability. Tests show that the proposed protocol does not harm the quality of the partitioning. Moreover it is quite efficient; each propagation step is extremely parallelizable and it is more stable than the asynchronous model, thanks to the fact that only a small amount of randomization is used by our proposal.Comment: In Proc. of The International Workshop on Business Applications of Social Network Analysis (BASNA '10

Synchronization of groups of coupled oscillators with sparse connections

Synchronization of groups of coupled oscillators with sparse connections are explored. It is found that different topologies of intergroup couplings may lead to different synchronizability. In the strong-coupling limit, an analytical treatment and criterion is proposed to judge the synchronization between communities of oscillators, and an optimal connection scheme for the group synchronization is given. By varying the intergroup and intragroup coupling strengths, different synchronous phases, i.e., the unsynchronized state, intragroup synchronization, intergroup synchronization, and global synchronization are revealed. The present discussions and results can be applied to study the pattern formation and synchronization of coupled spatiotemporal systems

Supporting and Enabling Scholarship: Developing and Sharing Expertise in Online Learning and Teaching

In a highly competitive, rapidly changing higher education market, universities need to be able to generate pedagogical expertise quickly and ensure that it is applied to practice. Since teaching approaches are constantly evolving, partly responding to emerging learning technologies, there is a need to foster ways to keep abreast on an ongoing basis. This paper explores how a small-scale project, the Teaching Online Panel (TOP), used scholarship investigations and a bottom-up approach to enhance one particular aspect of academic practice – online learning and teaching. The experiences of TOP are useful for identifying: - how a scholarship approach can help develop academic expertise - its contribution to enhancing understanding of staff’s different roles in the University - ways of developing the necessary supportive network for those undertaking such scholarship - the effectiveness of staff development which is peer-led rather than imposed from above - how practical examples can stimulate practice development - the relevance of literature on communities of practice and landscapes of practice for scholarship - the important role of ‘brokers’ to facilitate the dissemination of scholarship findings - the benefits to the brokers’ own professional roles - the challenges of sustaining such an approach and lessons learnt. This study has relevance for those involved in supporting scholarship or delivering staff development in Higher Education

Observations of expert communicators in immersive virtual worlds: implications for synchronous discussion

With the increased interest in using Immersive Virtual Worlds (IVWs) such as Second Life to augment and amplify teaching or to develop communities of practice, the author engaged graduate students, all current K‐12 teachers, in a qualitative study to examine their attitudes about communicating for the first time in a virtual setting represented by an interactive avatar. This study sought to determine if students were able to discern degrees of expertise in other avatars by providing encounters with guests who had a significant amount of experience navigating in a virtual world. The study examined Second Life as a synchronous discussion tool for a higher education setting and finds it lacking in some respects, but is able to make recommendations about training instructors to exhibit behaviours that may inspire confidence while leading a class in such a setting

Sampling design for compliance monitoring of surface water quality: A case study in a Polder area

International agreements such as the EU Water Framework Directive (WFD) ask for efficient sampling methods for monitoring natural resources. In this paper a general methodology for designing efficient, statistically sound monitoring schemes is described. An important decision is the choice between a design-based and a model-based method, implying the choice between probability (random) sampling and purposive sampling. For mapping purposes, model-based methods are more appropriate, whereas to obtain valid results for the universe as a whole, such as in testing water quality standards against legal standards, we generally prefer a design-based method. Four basic sampling patterns in space-time universe are described: static, synchronous, static-synchronous, and rotational. A case study is carried out for monitoring the quality of surface water at two farms in western Netherlands, wherein a synchronous sampling design is applied, with stratified simple random sampling in both space and time. To reduce laboratory costs the aliquots taken at the locations of a given sampling round are bulked to form a composite. To test the spatiotemporal mean N-total concentration during the summer half-year against the MAR standard with a power of 80% at a concentration 15% below the MAR standard and with a confidence of 95%, six to nine sampling rounds are needed with 50 to 75 locations per sampling round. For P-total the required number of sampling rounds differs strongly between the two farms, but is for both farms much larger than for N-total

Sampling design for compliance monitoring of surface water quality: A case study in a Polder area

International agreements such as the EU Water Framework Directive (WFD) ask for efficient sampling methods for monitoring natural resources. In this paper a general methodology for designing efficient, statistically sound monitoring schemes is described. An important decision is the choice between a design-based and a model-based method, implying the choice between probability (random) sampling and purposive sampling. For mapping purposes, model-based methods are more appropriate, whereas to obtain valid results for the universe as a whole, such as in testing water quality standards against legal standards, we generally prefer a design-based method. Four basic sampling patterns in space-time universe are described: static, synchronous, static-synchronous, and rotational. A case study is carried out for monitoring the quality of surface water at two farms in western Netherlands, wherein a synchronous sampling design is applied, with stratified simple random sampling in both space and time. To reduce laboratory costs the aliquots taken at the locations of a given sampling round are bulked to form a composite. To test the spatiotemporal mean N-total concentration during the summer half-year against the MAR standard with a power of 80% at a concentration 15% below the MAR standard and with a confidence of 95%, six to nine sampling rounds are needed with 50 to 75 locations per sampling round. For P-total the required number of sampling rounds differs strongly between the two farms, but is for both farms much larger than for N-total

Social networking and open educational resources: updating quality assurance for e-learning excellence

Quality assurance approaches in higher education are well-established, but it is important to develop methods which are applicable to the domain of e-learning. The E-xcellence methodology (EADTU, 2009a) was therefore designed to assess the quality of e-learning in distance learning and blended learning contexts. The methodology is based around a set of benchmarks, supported by a practitioner handbook and a web-based ‘QuickScan’ self-evaluation tool. Experience shows that the E-xcellence methodology is particularly valuable for the process of improvement through collaborative internal review. E-learning has evolved since the E-xcellence methodology was first developed. In particular, there is increasing awareness and use of open education resources (OERs) and social networking. However, these aspects were not explicit in the original E-xcellence resources. The E-xcellence Next project was therefore established to update the resources, incorporating these developments. To begin this process, a consultation was carried out among E-xcellence Next project members, followed by a participatory workshop on the themes of social networking and OERs. The E-xcellence resources were also used in a series of self-evaluation seminars held at European higher education institutions. Experience and feedback from these activities has been used to update the manual, the benchmarks and the QuickScan tool. The result is a set of quality assurance resources which encompass social networking, OERs and other recent developments in e-learning