Design and verification of a 24 kA calibration head for a DCCT test facility

The Large Hadron Collider (LHC) is CERN's next particle accelerator project, scheduled for commissioning in 2005. The project requires accurate current measurements above 10 kA. Calibration heads have been developed in collaboration with industry to work up to 24 kA at sub-ppm accuracy. The paper describes the design and verification

Chilled Water Storage Feasibility with District Cooling Chiller in Tropical Environment

The difficulties of efficiently operating a chiller cooling system are manifest in the high-energy consumption under partial-cooling loads. The performance of a chiller cooling system declines when operating away from the optimal design conditions, which is typically 75% of chiller capacity. One pathway has been found to overcome this problem using multiple smaller chillers within the same chiller plant, accompanied by a smart control system that is designed and constructed based on the cooling demand profile. Thermal energy storage integration with chiller cooling system is proposed to shave the cooling peak demand. This can be achieved by storing chilled water during the lower electricity-tariff period by the thermal energy storage system, which will then be discharged during the higher tariff-rate, thus, aiming for sustainable operating cost. The present paper studies the feasibility of sensible thermal energy storage to be integrated with two chillers, of 30-ton capacity each, under hot-and-humid climates. A computational model validated with experimental results is developed for three chiller cooling system case scenarios. The smart control scenario, as well as the thermal energy storage scenario results, showed great potential for energy and electricity cost saving. In addition, the carbon dioxide emissions reduction is calculated based on the amount of energy saving

Alternative antibody for the detection of CA19-9 antigen: a European multicenter study for the evaluation of the analytical and clinical performance of the Access (R) GI Monitor assay on the UniCel (R) Dxl 800 Immunoassay System

Background: Gastrointestinal cancer antigen CA19-9 is known as a valuable marker for the management of patients with pancreatic cancer. Methods: The analytical and clinical performance of the Access(R) GI Monitor assay (Beckman Coulter) was evaluated on the UniCel(R) Dxl 800 Immunoassay System at five different European sites and compared with a reference method, defined as CA19-9 on the Elecsys System (Roche Diagnostics). Results: Total imprecision (%CV) of the GI Monitor ranged between 3.4% and 7.7%, and inter-laboratory reproducibility between 3.6% and 4.0%. Linearity upon dilution showed a mean recovery of 97.4% (SD+7.2%). Endogenous interferents had no influence on GI Monitor levels (mean recoveries: hemoglobin 103%, bilirubin 106%, triglycerides 106%). There was no high-dose hook effect up to 115,000 kU/L. Clinical performance investigated in sera from 1811 individuals showed a good correlation between the Access' GI Monitor and Elecsys CA19-9 (R = 0.959, slope = 1.004, intercept +0.17). GI Monitor serum levels were low in healthy individuals (n = 267, median = 6.0 kU/L, 95th percentile = 23.1 kU/L), higher in individuals with various benign diseases (n = 550, medians = 5.8-13.4 kU/L, 95th percentiles = 30.1-195.5 kU/L) and even higher in individuals suffering from various cancers (n = 995, medians = 8.4-233.8 kU/L, 95th percentiles = 53.7-13,902 kU/L). Optimal diagnostic accuracy for cancer detection against the relevant benign control group by the GI Monitor was found for pancreatic cancer {[}area under the curve (AUC) 0.83]. Results for the reference CA19-9 assay were comparable (AUC 0.85). Conclusions: The Access(R) GI Monitor provides very good methodological characteristics and demonstrates an excellent analytical and clinical correlation with the Elecsys CA19-9. The GI Monitor shows the best diagnostic accuracy in pancreatic cancer. Our results also suggest a clinical value of the GI Monitor in other cancers

Declining trends in student performance in lower secondary education

Student performance is related to motivation to learn. As motivation generally declines during lower secondary education, one might expect performance to decline as well during this period. Though, until now, it has been unclear whether this pattern exists. In the present study, we examined student performance during the early years of secondary education from a developmental perspective. Participants were 1544 Dutch secondary school students across three grades (grades 7 to 9). To investigate student performance trends, we analysed report card grades by using hierarchical linear modelling with two levels (level 1, time point; level 2, student). Potential moderators to be examined were (1) gender, (2) school type and (3) initial level. A linear decline in report card grades from grade 7 to 9 was found for boys and girls, in all school types, and regardless of initial level. Two variables moderated the steepness of the decline: school type and initial level. Gender and school type had a main effect on performance level. The same pattern was observed for the subset of 'core subjects'-Dutch, English and mathematics. Motivational and cognitive factors that may explain the performance decline are discussed

Promoting performance and motivation through a combination of intrinsic motivation stimulation and an extrinsic incentive

During the early stages of secondary education students’ motivation and performance levels decline. This study employed a case study approach to evaluate a learning environment called GUTS; Differentiated Challenging of Talent in School. GUTS was specifically designed to raise performance and motivation through a combination of (a) talent lessons as an intrinsic motivator and (b) a higher promotion standard as an extrinsic incentive. Participants were 156 students who started secondary education in grade 7 in school year 2013/2014, and participated in GUTS for three successive school years. Performance and motivation measures were longitudinally collected between grades 7 and 9 and were analysed in comparison to previous cohorts of students at the same school and students at other schools. Additionally, measures of well-being and self-esteem were included to explore possible collateral effects of the intervention. The GUTS cohort displayed generally higher levels of performance and motivation than the comparison groups. However, the GUTS cohort still showed the decline of performance and motivation between grades 7 and 9 that was also observed in the comparison groups. This study showed that performance and motivation levels were increased without collateral damage to the students’ overall sense of well-being and self-esteem, while GUTS was not a strong enough intervention to counter the motivation and performance decline over time. Possible reasons for the persistent decline of student performance and motivation are discussed in terms of various factors at the level of GUTS, the educational context and the needs of the developing adolescent