Middle Grade Students' Interpretations of Contour Maps

This study examined eighth graders' approach to three tasks implemented to assist students with learning to interpret contour maps. Students' approach to and interpretation of these three tasks were analyzed qualitatively. When students were rank ordered according to their scores on a standardized test of spatial ability, the Minnesota Paper Form Board Task ( Likert & Quasha, 1948 ), evidence emerged that spatial ability was related to how students interpreted the tasks. Students with the relatively lowest spatial ability scores had difficulty picking out the relevant features of the representations used for instruction and despite scaffolding attempts by peers remained unclear about their interpretation. Students with relatively higher spatial ability were able to pick out salient features of the representations used for instruction which resulted in their learning to read and interpret contour maps.     

The Relationship Between Teacher and Student Beliefs About Mathematics

In this study the relationship between teacher (n = 7) beliefs about mathematics, the learning and teaching of mathematics and their respective students' beliefs about mathematics (n = 158) are examined. The data were collected by means of two instruments specifically designed to measure belief systems about mathematics. Teacher scores were adjusted so that a higher score reflected beliefs in aligntnent with the National Council of Teachers of Mathematics (NCTM) Standards. Results indicated that the students of teachers whose beliefs were in alignment with the NCTM Standards had significantly different beliefs about factors that lead to success in mathematics than did other students. Specifically these students felt that working hard to solve problems and striving for understanding would lead to success. No student differences were found for subscales of ego orientation, competitiveness, interest and extrinsic factors such as neatness and cooperation. These findings suggest that this group of teachers practiced what they believed and that these practices affected what their students believed about mathematics. We suggest that using these two assessments in tandem give a clearer picture of the mathematical environment within a classroom and can be used in professional development workshops to initiate teacher reflection about classroom practices.     

Interlaboratory comparison of methods for the determination of incurred tilmicosin residues in bovine liver

The objective of this study was to compare 2 methods for the determination of tilmicosin residues in bovine liver samples. Three laboratories participated in the comparison of the 2 methods. The first method was described in a New Animal Drug Application (NADA 140-929), and the second was a modification of that method in which hexane was substituted for carbon tetrachloride in one cleanup step. Each of the 3 laboratories analyzed subsamples of 10 bovine livers containing incurred tilmicosin. Residues ranged from 2.3 to 81 ppm tilmicosin in the 10 liver samples with an 11.8% relative standard deviation obtained by using both methods. In addition, fortified-control liver tissue samples were analyzed concurrently with tissues containing incurred residues by using the modified method in one of the laboratories. The fortification levels ranged from 0.3 to 112 ppm, with recoveries ranging from 76 to 92%. The results from the 3 laboratories were comparable, indicating that the modified method was not only as effective as the original NADA method, but also more desirable because of the change to a less hazardous solvent.     

Factors influencing first-year students' success in mathematics

Qualitative data from lecturers and students were used to identify factors which were perceived as making the most important contributions to students' academic success or failure in first-year mathematics courses. The study was conducted in three phases involving exploratory open-ended questionnaires, Likert-type questionnaires, and interviews. The results highlight both areas of similarities and areas of differences in lecturers' and students' perceptions about influences on student success and failure. While both students and lecturers acknowledged the importance of motivation, differences in perceptions suggest further research is needed in the areas of active learning, help-seeking, and student effort and workload.     

Apolipoprotein-E forms dimers in human frontal cortex and hippocampus

Background  

Apolipoprotein-E (apoE) plays important roles in neurobiology and the apoE4 isoform increases risk for Alzheimer's disease (AD). ApoE3 and apoE2 are known to form disulphide-linked dimers in plasma and cerebrospinal fluid whereas apoE4 cannot form these dimers as it lacks a cysteine residue. Previous in vitro research indicates dimerisation of apoE3 has a significant impact on its functions related to cholesterol homeostasis and amyloid-beta peptide degradation. The possible occurrence of apoE dimers in cortical tissues has not been examined and was therefore assessed. Human frontal cortex and hippocampus from control and AD post-mortem samples were homogenised and analysed for apoE by western blotting under both reducing and non-reducing conditions.     

Polarization Modulation Effects in Infrared–Infrared Four-Level Double Resonance inCH3F andNH3

The elements of the Jones matrices for an optically pumped sample have been derived and used to predict four-level double resonance absorption coefficients that are functions of the velocity component of the molecules in the direction of the pump beam for different polarizations of the probe beam. When a saturating pump and weak probe are used in four-level double resonance experiments under population modulation conditions, these absorption coefficients are found to depend only on the first three statistical tensor ranks:n= 0 (population), 1 (orientation), and 2 (alignment). It is also found that for polarization modulation experiments with plane-polarized radiation, the absorption coefficient depends only on the alignment of them-state populations. Similarly, for polarization modulation with circularly polarized radiation, the absorption coefficient depends only on the orientation. The theory was used to interpret double-resonance polarization modulation experiments in¹³CH₃F and¹⁵NH₃in order to examine the effects of collisions on the initial anisotropy of the projection ofJon a space-fixedZaxis. The four-level double-resonance lineshapes were fit by least squares to absorption coefficients predicted by the theory. The collisional effects were modeled by a sum of Keilson–Storer collision kernels. The results of the fits were much improved when the value of the effective rate constant for the transfer of then= 0 tensor from the upper level of the pump to the lower level of the probe was larger than the values of the effective rate constants for the transfer of then= 1 and 2 populations. The best ratio of the rate constant forn> 0 to that forn= 0 is about 2/3 for¹³CH₃F and 1/3 for¹⁵NH₃. Additional analysis of the lineshapes showed the importance of long-range dipole–dipole interactions, elastic realignment and reorientation, and V–V mechanisms for collision-induced rotational energy transfer in¹³CH₃F and¹⁵NH₃.     

A test of performance of breast MRI interpretation in a multicentre screening study

OBJECTIVES: The aim of this study was to assess the consistency and performance of radiologists interpreting breast magnetic resonance imaging (MRI) examinations. MATERIALS AND METHODS: Two test sets of eight cases comprising cancers, benign disease, technical problems and parenchymal enhancement were prepared from two manufacturers' equipment (X and Y) and reported by 15 radiologists using the recording form and scoring system of the UK MRI breast screening study [(MAgnetic Resonance Imaging in Breast Screening (MARIBS)]. Variations in assessments of morphology, kinetic scores and diagnosis were measured by assessing intraobserver and interobserver variability and agreement. The sensitivity and specificity of reporting performances was determined using receiver operating characteristic (ROC) curve analysis. RESULTS: Intraobserver variation was seen in 13 (27.7%) of 47 of the radiologists' conclusions (four technical and seven pathological differences). Substantial interobserver variation was observed in the scores recorded for morphology, pattern of enhancement, quantification of enhancement and washout pattern. The overall sensitivity of breast MRI was high [88.6%, 95% confidence interval (CI) 77.4-94.7%], combined with a specificity of 69.2% (95% CI 60.5-76.7%). The sensitivities were similar for the two test sets (P=.3), but the specificity was significantly higher for the Manufacturer X dataset (P<.001). ROC curve analysis gave an area under the curve of 0.85 (95% CI 0.79-0.92) CONCLUSIONS: Substantial variation in all elements of the scoring system and in the overall diagnostic conclusions was observed between radiologists participating in MARIBS. High overall sensitivity was achieved with moderate specificity. Manufacturer-related differences in specificities possibly occurred because the numerical thresholds set for the scoring system were not optimised for both equipment manufacturers. Scoring systems developed on one equipment software may not be transferable to other manufacturers.     

Interlaboratory determination of boron compounds in preservative treated timber

Accurate analysis for preservatives in treated timber is an integral part of quality assurance in the New Zealand timber preservation industry. The continued high volume use of boron-treated timber has highlighted the requirement for reliable methods to determine boron-containing preservatives in timber. Several aspects of a leaching-titration method are discussed in an effort to validate and standardize laboratory analysis of samples for the timber preservation industry. Steam volatility was found not to be a problem. The limit of detection was 0.007% (w/w) H₃BO₃ and the relative standard deviation of 50 replicate analyses was 2.2%. Statistical outliers and stragglers were identified by Cochran's test. The precision data (repeatability and reproducibility) from an interlaboratory determination of boric acid in timber were 0.0133–0.0273 and 0.0194–0.0535% H₃BO₃, respectively, over six concentration levels. Recommendations for maintaining active quality assurance programmes are made.