Diet partitioning, habitat preferences and behavioral interactions between juvenile yellow perch and round goby in nearshore areas of Lake Erie

Ecological interactions between native and non-indigeneous species depend on interspecies dietary and habitat overlap and species-specific behavior. In the Great Lakes, the exotic round goby (Apollonia melanostoma) is very abundant in littoral areas used by the native yellow perch (Perca flavencens). We examined yellow perch-round goby interactions using multiple approaches. Field surveys analyzing dietary overlap among three size classes of yellow perch and round goby detected significant overlap only between juvenile perch (< 95 mm TL) and gobies (< 60 mm TL). Laboratory experiments using juvenile stages tested for habitat preference differences (open sand, macrophytes and dreissenids) in solitary, intraspecific (2 perch) and interspecific (1 perch, 1 goby) treatments. In macrophyte and dreissenid habitats, we tested for treatment differences in fish behavior (intraspecific vs. interspecific) and yellow perch growth (solitary, intraspecific and interspecific). Round goby consistently preferred complex habitats. Yellow perch showed diurnal preference of complex habitats, but increased nocturnal use of sand in the solitary and interspecific treatments. Activity was greater in dreissenid than macrophyte habitat, but prey attacks showed the opposite trend. Activity and prey attacks were greater in the intraspecific than interspecific treatments. The trend was due to lower prey attacks executed by round goby. In macrophytes, individual yellow perch growth was lower in the intraspecific than in the solitary and interspecific treatments. In dreissenids, intraspecific and interspecific competitors equally decreased yellow perch growth. Our results suggest differences in diet, habitat preference and behavior between juvenile round goby and yellow perch may allow their coexistence in nearshore areas.     

Development aid and access to water and sanitation in Sub-Saharan Africa

This paper compares countries’ performance in the water and sanitation sector and analyzes how effectively they used the development aid targeted for this sector. These analyses are validated by presentation of the water and sanitation situation of four case-study countries: Kenya, Madagascar, Burkina Faso and Uganda. The paper also utilizes the innovative Watsan Index of Development Effectiveness, which compares drivers of progress with results achieved and ranks African countries by the level of outcome obtained per unit of available input in the four case-study countries.     

The Potential for Calculating a Meaningful Water Poverty Index

Abstract

One of the most significant failures in the development process has been our inability to match water demand to its supply. For a large portion of the world's population, this has meant a lack of provision of adequate water for domestic use, resulting in a significant loss of time and effort, especially on the part of women. While science can now provide us with detailed assessments of water resource availability, little to date has been done to link this to our knowledge of human resources and their geographical distributions. In order to manage these resources better, it is essential that they be addressed in a more holistic way. This paper provides a preliminary discussion of possible ways in which an interdisciplinary approach can be taken to produce a more holistic assessment of water stress, in such a way as to link physical estimates of water availability with the socio-economic drivers of poverty. To this end, some approaches to creating a Water Poverty Index are discussed, and it is hoped that this paper will generate interest and debate among a wide range of readers.     

Preconceptions and Individual Differences in Understanding Visual Metaphors

Understanding information visualization is more than a matter of reading a series of data values; it is also a matter of incorporating a visual structure into one's own thinking about a problem. We have proposed visual metaphors as a framework for understanding high-level visual structure and its effect on visualization use. Although there is some evidence that visual metaphors can affect visualization use, the nature of this effect is still ambiguous. We propose that a user's preconceived metaphors for data and other individual differences play an important role in her ability to think in a variety of visual metaphors, and subsequently in her ability to use a visualization. We test this hypothesis by conducting a study in which a participant's preconceptions and thinking style were compared with the degree to which she is affected by conflicting metaphors in a visualization and its task questions. The results show that metaphor compatibility has a significant effect on accuracy, but that factors such as spatial ability and personality can lessen this effect. We also find a complex influence of self-reported metaphor preference on performance. These findings shed light on how people use visual metaphors to understand a visualization.     

Community Development Among Distance Learners: Temporal and Technological Dimensions

Internet self-efficacy, or the belief in one's capabilities to organize and execute courses of Internet actions required to produce given attainments, is a potentially important factor in efforts to close the digital divide that separates experienced Internet users from novices. Prior research on Internet self-efficacy has been limited to examining specific task performance and narrow behavioral domains rather than overall attainments in relation to general Internet use, and has not yielded evidence of reliability and construct validity. Survey data were collected to develop a reliable operational measure of Internet self-efficacy and to examine its construct validity. An eight-item Internet self-efficacy scale developed for the present study was found to be reliable and internally consistent. Prior Internet experience, outcome expectancies and Internet use were significantly and positively correlated to Internet self-efficacy judgments. Internet stress and self-disparagement were negatively related to Internet self-efficacy. A path analysis model was tested within the theoretical framework of social cognitive theory ( Bandura (1997) .     

Beyond sentence-level semantic role labeling: linking argument structures in discourse

Semantic role labeling is traditionally viewed as a sentence-level task concerned with identifying semantic arguments that are overtly realized in a fairly local context (i.e., a clause or sentence). However, this local view potentially misses important information that can only be recovered if local argument structures are linked across sentence boundaries. One important link concerns semantic arguments that remain locally unrealized (null instantiations) but can be inferred from the context. In this paper, we report on the SemEval 2010 Task-10 on “Linking Events and Their Participants in Discourse”, that addressed this problem. We discuss the corpus that was created for this task, which contains annotations on multiple levels: predicate argument structure (FrameNet and PropBank), null instantiations, and coreference. We also provide an analysis of the task and its difficulties.     

The influence of precision requirements and cognitive challenges on upper extremity joint reaction forces,moments and muscle force estimates during prolonged repetitive lifting

Prolonged repetitive lifting is a whole-body exertion. Despite this, the roles and physical exposures of the upper extremities are frequently neglected. The influence of precision requirements and cognitive distractions on upper extremity responses when lifting was evaluated by quantifying several biomechanical upper extremity quantities. Nine participants completed four 30-min lifting tasks with and without simultaneous cognitive distractions and/or precision placement constraints. Specific metrics evaluated were joint reaction forces and moments (wrist, elbow and shoulder) and modelled shoulder muscle forces (38 defined shoulder muscle mechanical elements). The addition of a precision requirement increased several metrics by up to 43%, while the addition of the cognitive distraction task had minimal influence. Furthermore, several metrics decreased by up to 14% after the first 10 min of lifting, suggesting a temporal change of lifting strategy.     

Life-span changes in the copulatory behavior of male rats (Rattus norvegicus).

Studied the copulatory behavior of 36 5-, 10-, 15-, and 20-mo old sexually naive male Long-Evans rats during 2-hr tests with receptive females. There was no apparent change in sexual arousal as measured by latency to initiate copulation across age, with Ss from all groups exhibiting comparable latencies to 1st mount and 1st mount with intromission. The numbers of ejaculations achieved were also similar across ages. Significant age differences were found for frequency of mounts, with 20-mo olds having the highest mean frequency. The persistent mounting by older Ss appeared to account for significant group differences in interintromission interval and ejaculation latency. It is suggested that motor deficits may impair the ability of older Ss to achieve intromission, increasing the number of mount bouts as well as the number of mounts for each bout, thus extending the length of each copulatory series. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Argumentation frameworks as constraint satisfaction problems

Argumentation is a promising approach for defeasible reasoning. It consists of justifying each plausible conclusion by arguments. Since the available information may be inconsistent, a conclusion and its negation may both be justified. The arguments are thus said to be conflicting. The main issue is how to evaluate the arguments. Several semantics were proposed for that purpose. The most important ones are: stable, preferred, complete, grounded and admissible. A semantics is a set of criteria that should be satisfied by a set of arguments, called extension, in order to be acceptable. Different decision problems related to these semantics were defined (like whether an argumentation framework has a stable extension). It was also shown that most of these problems are intractable. Consequently, developing algorithms for these problems is not trivial and thus the implementation of argumentation systems not obvious. Recently, some solutions to this problem were found. The idea is to use a reduction method where a given problem is translated in another one like SAT or ASP. This paper follows this line of research. It studies how to encode the problem of computing the extensions of an argumentation framework (under each of the previous semantics) as a constraint satisfaction problem (CSP). Such encoding is of great importance since it makes it possible to use the very efficient solvers (developed by the CSP community) for computing the extensions. Our encodings take advantage of existing reductions to SAT problems in the case of Dung’s abstract framework. Among the various ways of translating a SAT problem into a CSP one, we propose the most appropriate one in the argumentation context. We also provide encodings in case two other families of argumentation frameworks: the constrained version of Dung’s abstract framework and preference-based argumentation framework.     

Effects of feedback in a computer-based assessment for learning

The effects of written feedback in a computer-based assessment for learning on students’ learning outcomes were investigated in an experiment at a Higher Education institute in the Netherlands. Students were randomly assigned to three groups, and were subjected to an assessment for learning with different kinds of feedback. These are immediate knowledge of correct response (KCR) + elaborated feedback (EF), delayed KCR + EF, and delayed knowledge of results (KR). A summative assessment was used as a post-test. No significant effect was found for the feedback condition on student achievement on the post-test. Results suggest that students paid more attention to immediate than to delayed feedback. Furthermore, the time spent reading feedback was positively influenced by students’ attitude and motivation. Students perceived immediate KCR + EF feedback to be more useful for learning than KR. Students also had a more positive attitude towards feedback in a CBA when they received KCR + EF rather than KR only.