Carbon dioxide as working gas for laboratory plasmas

Measurements with a RF probe, retarding potential analyzer and mass spectrometer in a laboratory plasma tank were performed using the gases CO2, N2, A and He in order to compare their properties as working gases for laboratory plasma production. The overall result of that CO2 leads to higher plasma densities at lower neutral-gas pressures as well as to a larger Maxwellian component of the electron population, while the electron temperature is lower than that when N2, A and He are used

Optomotor Swimming in Larval Zebrafish Is Driven by Global Whole-Field Visual Motion and Local Light-Dark Transitions

Stabilizing gaze and position within an environment constitutes an important task for the nervous system of many animals. The optomotor response (OMR) is a reflexive behavior, present across many species, in which animals move in the direction of perceived whole-field visual motion, therefore stabilizing themselves with respect to the visual environment. Although the OMR has been extensively used to probe visuomotor neuronal circuitry, the exact visual cues that elicit the behavior remain unidentified. In this study, we use larval zebrafish to identify spatio-temporal visual features that robustly elicit forward OMR swimming. These cues consist of a local, forward-moving, off edge together with on/off symmetric, similarly directed, global motion. Imaging experiments reveal neural units specifically activated by the forward-moving light-dark transition. We conclude that the OMR is driven not just by whole-field motion but by the interplay between global and local visual stimuli, where the latter exhibits a strong light-dark asymmetry

Providing equivalent learning activities with software-based remote access laboratories

Laboratory-based learning activities are important components of engineering and surveying education and it is difficult to offering practical activities to distance education students. Remote Access Laboratory (RAL) systems are widely discussed as learning tools to offer students remote access to rigs or hardware. In some disciplines laboratory activities are purely software based and RAL systems can be used to provide access to software. As part of a larger study into the transferability of the remote laboratory concept to non-engineering disciplines this project evaluates the effectiveness of RAL based software activities in supporting student learning is investigated. In the discipline of Surveying and Spatial Science, RAL technology is used to provide Geographic Information System software access to distance students. The key research question discussed in this paper is whether RALbased software activities can address the same learning outcomes as face-to-face practical classes for software activities. Data was collected from students' discussion forums, teaching staff diaries and teaching staff interviews. The project demonstrates that students undertaking learning activities remotely achieve similar learning outcomes than student in practice classes using the same software. Ease of system access and usability are critical and the learning activity needs to be supported by comprehensive learning materials. This research provides a clear case in which the use of RAL technology has provided inclusive educational opportunities more efficiently and these general results are also applicable to experiments that involve physical hardware

Generalized Kruithof approach for traffic matrix estimation

[Abstract]: In this paper, the traffic matrix estimation problem is formulated as an nonlinear optimization problem based on the generalized Kruithof approach which uses the Kullback distance to measure the probabilistic distance between two traffic matrices. In addition, an algorithm using the affine scaling method is provided to solve the constraint optimization problem

Functionele aspecten van de gecomputeriseerde lexicografie

Functional Aspects of Computerised Lexicography. The computerisation of lexicography has meant that traditional dictionaries are now supported, supplemented and - in some places - already supplanted by new electronic off- and online information carriers. The Woordenboek der Nederlandsche Taal (WNT) which was "completed" in 1998 and its electronic successors form a case study of these developments. In addition to a short description of the WNT project, this article also focuses on the functional aspects of computerised lexicography. Some of the more general aspects of information and knowledge technology are stressed, including the role of the user who needs to carry out his/her searches through the language banks of the future with the least possible effort.Keywords: Computerised lexicography, electronic dictionary, electronic publishing, information and communication technology, on-line access via internet, user interfac

A Comparative Analysis of the Metabolism and Energetics of Darters (Percidae)

Ecological niche theory suggests two species cannot live in the same ecological niche and differences should exist among species that appear to cohabitate. Variations in physiology and behavior that potentially enable species coexistence can be reflected in metabolism. This study investigated coexisting darter fishes by measuring the metabolism of greenside (Etheostoma blennioides) and variegate (E. variatum) darters over 48 h using intermittent-flow respirometry. Activity was analyzed using time-lapse videos. E. blennioides mean metabolic rate (154.64 ± SE 52.54 mg O2·kg-1 ·hr-1 ; n=14; p=0.0006) was significantly greater than and varied more than E. variatum’s mean rate (92.51 ± SE 32.70 mg O2·kg-1 ·hr-1 ; n=15). E. blennioides had consistently elevated activity compared to E. variatum, but was not significantly different over time (F1,4=3.24, p=0.5173); while E. variatum’s activity was (F1,4=20.50, p=0.0004). The results may suggest that E. blennioides is a bolder, more active species than E. variatum. Physiological and behavioral differences revealed between E. blennioides and E. variatum could potentially explain their coexistence. Second, a comparison of published studies on darter metabolism was conducted to elucidate interspecific variation among a greater number of darter species. This search resulted in metabolic data on a total of 11 darter species, which were compared to the current study in three ways (using the 48 h mean rates, the first 4.5 h mean rates, and the middle 24 h mean rates). The results showed interspecific variation in metabolic rates among darters, but also illustrated the importance of developing methods that measure metabolism accurately. Finally, this study helped uncover differences among darters using a physiological approach and will hopefully lead to an increased interest in quantitative darter physiological ecology

Assessing culturally and linguistically diverse stuents : a discussion for professionals in the schools

This paper is intended for professional school psychologists, school social workers, consultants in special education and other professionals involved in assessment issues in the schools. It is necessary for school professionals to have an understanding of the general socio-political context which surrounds the issues involved in language and culture to better assess the mental/cognitive abilities of language minority students through the dominant language and culture. It is beyond the scope of this paper to present such issues in their entirety. Therefore, the focus of this paper will center on voluntary minorities , specifically those who are learning English as a second language and those minorities who are from linguistically and culturally diverse groups