We have used seven different techniques to measure the anisotropic refractive index of poly(vinylcarbazole) films. These techniques are: two types of variable angle spectroscopic ellipsometry (VASE) with multiple sample analysis, Interference enhanced VASE, Transmittance combined with VASE, Polarised Reflectance, beta‐scan VASE, and prism coupling. We have found the average ordinary and extraordinary indices at 633 nm to be no = nTE = 1.675 ± 0.008, and ne = nTM = 1.722 ± 0.018, respectively, consistent amongst methods and conclusive on the magnitude of Δn in polymer films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Small-scale gold mining activities and their mercury emissions in the Gorontalo Utara Regency of the Gorontalo Province, Sulawesi Island, Indonesia, have been studied. The mining occurs in many areas of this region, but especially in the three villages Hulawa, Ilangata and Ilangata Barat. Mining activities in the Hulawa village are the oldest (19th century) in the regency, whereas mining in the Ilangata village began just 15 years ago. The activity level changes rapidly from time to time depending on the fluctuations of the gold market. Women and children are involved in the gold mining process. Female workers crush ore, process sediment wastes, and pan for gold in rivers. Children assist their mothers in these activities and play around the mining sites. Gold mining in the Utara Regency is estimated to produce about 290 kg of gold and emits approximately 860 kg of mercury into the environment annually. The impact of such large mercury release into the environment have caused environmental degradation and contamination of fish as food for humans. Collaborative works of stakeholders are urgently needed to find solutions to the problems related to small-scale gold mining such as marginalization and environmental pollution.

This research aimed to evaluate the students’ conceptual understanding and to diagnose the students’ preconceptions in elaborating the particle characteristics of matter by development of diagnostic instrument as well as Rasch model response pattern analysis approach. Data were acquired by 25 multiple-choice written test items distributed to 987 students in North Sulawesi, Indonesia. Analysis on diagnostic test items response pattern was conducted in three steps: 1) conversion of raw score to a homogenous interval unit and effectiveness analysis of measurement instruments; 2) measurement of disparity of students’ conceptual understanding; and 3) diagnosis of students’ preconception by estimation of item response pattern. The result generated information on the diagnostic and summative measurement on students’ conceptual understanding in elaborating the topic; information also acts as empirical evidence on the measurement’s reliability and validity. Moreover, the result discovered a significant disparity between students’ conceptual understanding based on their educational level. It was found that the distractor item response pattern tended to be consistent, indicating a certain tendency of resistant preconception pattern. The findings are expected to be a recommendation for future researchers and educational practitioners that integrate diagnostic and summative measurement with Rasch model in evaluating conceptual understanding and diagnosing misconception. Keywords: conceptual understanding, item response, particle of matter, Rasch model

We prepared thin films of the conjugated polymer poly(3-butylthiophene) by spin-coating and performed transmission and reflection spectroscopy to characterize the dispersion of linear refractive index and absorption coefficient at in-plane polarization. Slab waveguides of this regiorandom polythiophene derivative have mode propagation losses smaller than 1 dB/cm at wavelengths larger than 1000 nm. We determined the nonlinear refractive index and two-photon absorption of slab waveguides by means of intensity-dependent prism coupling using picosecond laser pulses in the range 700–1300 nm. These data yield the dispersion of the figures of merit, which appear promising for all-optical waveguide switching at wavelengths larger than 1200 nm.