Home About us Contact
|
Home About us Contact | ||
|
|
||
Test Design (test + design)
Selected AbstractsDevelopment and field validation of a predictive copper toxicity model for the green alga Pseudokirchneriella subcapitataENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2003Karel A. C. De Schamphelaere Abstract In this sudy, the combined effects of pH, water hardness, and dissolved organic carbon(DO) concentration and type on the chronic (72-h) effect of copper on growth inhibition of the green alga Pseudokirchneriella subcapitata were investigated. Natural dissolved organic matter (DOM) was collected at three sites in Belgium and The Netherlands using reverse osmosis. A full central composite test design was used for one DOM and a subset of the full design for the two other DOMs. For a total number of 35 toxicity tests performed, 72-h effect concentration resulting in 10% growth inhibition (EbC10s) ranged from 14.2 to 175.9 ,g Cu/L (factor 12) and 72-h EbC50s from 26.9 to 506.8 ,g Cu/L (factor 20). Statistical analysis demonstrated that DOC concentration, DOM type, and pH had a significant effect on copper toxicity; hardness did not affect toxicity at the levels tested. In general, an increase in pH resulted in increased toxicity, whereas an increase of the DOC concentration resulted in decreased copper toxicity. When expressed as dissolved copper, significant differences of toxicity reduction capacity were noted across the three DOM types tested (up to factor 2.5). When expressed as Cu2+ activity, effect levels were only significantly affected by pH; linear relationships were observed between pH and the logarithm of the effect concentrations expressed as free copper ion activity, that is, log(EbC50) and log(EbC10): (1) log(EbC50) = ,1.431 pH + 2.050 (r2 = 0.95), and (2) log(EbC10) = ,1.140 pH , 0.812 (r2 = 0.91). A copper toxicity model was developed by linking these equations to the WHAM V geochemical speciation model. This model predicted 97% of the EbC50dissolved and EbC10dissolved values within a factor of two of the observed values. Further validation using toxicity test results that were obtained previously with copper-spiked European surface waters demonstrated that for 81% of tested waters, effect concentrations were predicted within a factor of two of the observed. The developed model is considered to be an important step forward in accounting for copper bioavailability in natural systems. [source] Individual Odour Similarity and Discrimination in the Coruro (Spalacopus cyanus, Octodontidae)ETHOLOGY, Issue 6 2006Petra Hagemeyer Previous studies of subterranean, fossorial and above-ground rodents have demonstrated that similarities in individual odours covary with genetic similarities thus supporting the theory of odour-genes covariance (i.e. the closer the individuals are genetically, the greater the similarities between their odours). We used the habituation-generalization paradigm, where the subject is exposed to the same odour stimulus in three consecutive habituation trials followed by two test trials in which the odour from two other individuals are presented successively. Using this test design, we showed that the socially living coruros (Spalacopus cyanus) discriminate individuals on the basis of their ano-genital odours and also respond to odour similarities between individuals. Male and female subjects treated ano-genital odours of two same-sex family members and also the odours of two sibling strangers as different to each other. At the same time, they treated the odours of siblings as similar compared with the odour of an unrelated individual. No gender differences were detected. Our results contrast with those from other rodent species that did not spontaneously discriminate between individual odours of siblings from a different family than their own. The polygyneous lifestyle may provide the selective background for that difference. Additional research will be necessary to explore this hypothesis and to rule out differences due to dietary preferences and due to the type of paradigm chosen for the tests. [source] A computer-assisted test design and diagnosis system for use by classroom teachersJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 6 2005Q. He Abstract Computer-assisted assessment (CAA) has become increasingly important in education in recent years. A variety of computer software systems have been developed to help assess the performance of students at various levels. However, such systems are primarily designed to provide objective assessment of students and analysis of test items, and focus has been mainly placed on higher and further education. Although there are commercial professional systems available for use by primary and secondary educational institutions, such systems are generally expensive and require skilled expertise to operate. In view of the rapid progress made in the use of computer-based assessment for primary and secondary students by education authorities here in the UK and elsewhere, there is a need to develop systems which are economic and easy to use and can provide the necessary information that can help teachers improve students' performance. This paper presents the development of a software system that provides a range of functions including generating items and building item banks, designing tests, conducting tests on computers and analysing test results. Specifically, the system can generate information on the performance of students and test items that can be easily used to identify curriculum areas where students are under performing. A case study based on data collected from five secondary schools in Hong Kong involved in the Curriculum, Evaluation and Management Centre's Middle Years Information System Project, Durham University, UK, has been undertaken to demonstrate the use of the system for diagnostic and performance analysis. [source] Long-term effects of computer training of phonological awareness in kindergartenJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 1 2005Eliane Segers Abstract The present study examined the long-term effects of a computer intervention for the development of phonological awareness in Dutch kindergartners. Native Dutch and immigrant children worked with the software 15 min/week during one school year. Following a pretest , interim test , post-test , retention test design, the effects on rhyming, phonemic segmentation, auditory blending, and grapheme knowledge were assessed. The intervention showed significant immediate effects on rhyming and grapheme knowledge. The time spent on the computer games also correlated with the learning gains for the experimental group. In the first grade, retention effects were demonstrated after 4 months of formal reading education. [source] Small-Sample Equating Using a Synthetic Linking FunctionJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 4 2008Sooyeon Kim This study addressed the sampling error and linking bias that occur with small samples in a nonequivalent groups anchor test design. We proposed a linking method called the synthetic function, which is a weighted average of the identity function and a traditional equating function (in this case, the chained linear equating function). Specifically, we compared the synthetic, identity, and chained linear functions for various-sized samples from two types of national assessments. One design used a highly reliable test and an external anchor, and the other used a relatively low-reliability test and an internal anchor. The results from each of these methods were compared to the criterion equating function derived from the total samples with respect to linking bias and error. The study indicated that the synthetic functions might be a better choice than the chained linear equating method when samples are not large and, as a result, unrepresentative. [source] A Bayesian zero-failure reliability demonstration test of high quality electro-explosive devicesQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 8 2009Tsai-Hung Fan Abstract Usually, for high reliability products the production cost is high and the lifetime is much longer, which may not be observable within a limited time. In this paper, an accelerated experiment is employed in which the lifetime follows an exponential distribution with the failure rate being related to the accelerated factor exponentially. The underlying parameters are also assumed to have the exponential prior distributions. A Bayesian zero-failure reliability demonstration test is conducted to design forehand the minimum sample size and testing length subject to a certain specified reliability criterion. Probability of passing the test design as well as predictive probability for additional experiments is also derived. Sensitivity analysis of the design is investigated by a simulation study. Copyright © 2009 John Wiley & Sons, Ltd. [source] Artificial disruption of skin barrier prior to irritant patch testing does not improve test designBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2004K.L. Gebhard Summary Background, Irritant patch testing is often performed as a 24- or 48-h occlusive patch test with low concentrations of sodium lauryl sulphate (SLS). Objectives, The aim of this study was to investigate potential ways to shorten this test procedure and obtain precise test results. Patients and methods, Thirty-six healthy volunteers underwent irritant patch testing with different pretreatments (PT) of the test fields. Occlusive test chambers were applied on the upper back with SLS 0·5%, 1%, 2% and 5% in large Finn Chambers®. The patches were removed after 4 and 24 h, respectively, depending on the concentration used. Test fields were pretreated as follows: PT 0, field without any PT (control); PT 1, prick with lancet; PT 2, prick with test stamp; PT 3, scratch with lancet; PT 4, incision with standardized incision instrument (0·1,0·2 mm depth). Skin reactions were evaluated by transepidermal water loss (TEWL), skin erythema and skin hydration and as well by a visual score (VS) at 4, 24 and 72 h. Results, Our data show an obvious distinction between PT 0,2 and PT 3,4 at all measurement methods. The average TEWL values with PT 3,4 were higher than those with PT 0,2, especially on the 4-h course. This distinction may derive from the shape and size of the skin impairment achieved by PT 3,4, leading to a mechanical barrier disruption. However, SLS may infiltrate directly into deeper skin layers supported by capillarity. Consequently, no or little penetration through the epidermis and interaction with its structures occurs, which is responsible for irritant skin reactions. The SLS dose in the upper skin layers is therefore lower at these PTs. The lower remaining dose of SLS also explains this distinction, especially for the VS. Additionally, there are presumed reactions in deeper layers of the epidermis and dermis at PT 3,4. Conclusions, In summary, all data suggest a different reaction pattern from the classical irritant response. Therefore, application without any PT seems to be best suited for irritancy skin testing, especially for visual assessment. PTs prior to irritant patch testing have been shown to be unjustifiable. [source] 4421: The fundamentals of visual acuity measurementACTA OPHTHALMOLOGICA, Issue 2010CM CHISHOLM Purpose To provide the background to the symposium on visual acuity and its measurement Methods The parameters employed to quantify visual performance will be defined. Commonly used measurement techniques ranging from traditional letter charts to psychophysical computer-based programmes, will be described and compared, with reference to the peer-reviewed literature in this area. The issues of accuracy and repeatability will be considered in the context of the clinical setting and scientific studies. Results Letter charts are most commonly employed to assess visual performance because of their ease of use for both the patient and assessor, but they suffer from design limitations. Psychophysical procedures are more flexible and can improve repeatability, but are time consuming and fatigue can start to play a part. Such techniques are generally more suited to the research environment. High contrast visual acuity measurement can give a misleading impression regarding the quality of vision. This is particularly the case for subjects with impaired optical quality relating to an increase in intraocular light scatter and/or increased higher order aberrations. Assessment in the contrast domain is essential to build up a fuller picture. Conclusion The assessment of visual quality requires an understanding of test design and limitations. The method used should be chosen to suit the aims of the work and partly depends on whether it is taking place in a clinical practice setting or as part of a research study. [source] Reducing the length of mental health instruments through structurally incomplete designsINTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 3 2007Niels Smits Abstract This paper presents structurally incomplete designs as an approach to reduce the length of mental health tests. In structurally incomplete test designs, respondents only fill out a subset of the total item set. The scores on the unadministered items are estimated using methods for missing data. As an illustration, structurally incomplete test designs recording, respectively, two thirds, one half, one third and one quarter of the complete item set were applied to item scores on the Centre of Epidemiological Studies-Depression (CES-D) scale of the respondents in the Longitudinal Aging Study Amsterdam (LASA). The resulting unobserved item scores were estimated with the missing data method Data Augmentation. The complete and reconstructed data yielded very similar total scores and depression classifications. In contrast, the diagnostic accuracy of the incomplete designs decreased as the designs had more unobserved item scores. The discussion addresses the strengths and limitations of the application of incomplete designs in mental health research. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||||||||