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Introduction: Opening the incubator side wall to insert a non-sterile length-measuring device carries the risk of microbial contamination and thermal instability for preterm infants. To reduce this inconvenience, a laser-based length-measuring board is proposed to measure body length from outside the incubator. Methods: This device has two laser-line-shaped cursors which can be pointed to opposite ends of a segment to be measured. It is attached to the outer side of one of the incubator's side walls in such a manner as to ensure that its axis is parallel to the longitudinal axis of the segment. To validate the measurements made with this model, a calibrated caliper consisting of a conventional rigid length-measuring board with a resolution of 0.05 mm was constructed to serve as a reference. Crown–heel length was measured in a sample of 45 infants, including 32 preterm and 13 term infants of corrected gestational age at the time of measurement. Results: Good intra-observer variability was obtained. Near-perfect statistical agreement was found between measurements with both devices, with concordance correlation coefficients of 0.994 (95% CI: 0.990; 0.996) in preterm infants and 0.994 (95% CI: 0.988, 0.998) in infants at term. The clinical relevance of the agreement between measurements was assessed by a Bland–Altman plot, and the difference may reach clinical relevance (up to 1 cm) but without evidence of proportional bias. Conclusion: The proposed validated laser-based length-measuring board offers a suitable alternative to conventional length-measuring boards for contactless measurement of infant body length. [ABSTRACT FROM AUTHOR]

Students in three sections of introductory psychology, N = 1051, were asked about the utility of traditional, e.g. instructor, lectures and textbook, and nontraditional, e.g., clickers, podcasts and online lecture slides, teaching tools. Students who felt unprepared for college (25.9%) differed from their peers in their perceived utility of these tools. Both groups of students reported that novel teaching tools were less helpful than traditional teaching tools and while there was no group difference in the perceived usefulness of the novel tools, underprepared students found traditional teaching tools to be less helpful than did prepared students. When the individual tools were used to predict the amount of self-reported learning gains in these students, it was the traditional teaching tools that accounted for the greater proportion of variability in overall learning. These results suggest that, rather than adding new approaches to their teaching, instructors could best assist their underprepared students by helping them learn to make better use of traditional teaching tools.

Previously, we showed that at low temperatures and very low excitation powers, EuTe displays band-edge photoluminescence with a well-resolved phonon structure, the so-called MX 0 band, which is associated with the recombination of giant spin polarons (SPs) of magnetic moments of several hundred Bohr magnetons. Here, we investigate the MX 0 band both experimentally and by Monte Carlo simulations. Results indicate that the SPs are bound to defects, with a localization energy of 0.29 eV. The density of defects harboring the SPs is estimated to be 4.3 × 10 15 cm − 3 . [ABSTRACT FROM AUTHOR]

We investigated the time evolution of the density of giant spin polarons in a magnetic semiconductor. Spin polarons (SPs) were photoexcited and observed using time-resolved Faraday rotation. We find the existence of two types of SPs, a short-lived spin polaron with a lifetime of around τsl = 0.5 ns and a long-lived spin polaron with a lifetime of τll = 0.45 ± 0.03 µs, at T = 5 K. The stark difference of three order of magnitude between these lifetimes suggests that in the long lived SP the electron-hole pair is relaxed and its recombination is forbidden. The short-lived SP is probably associated with SP recombination before such relaxation has occured. An extraordinary finding is that the magnitude of τsl, as well as its decrease with increasing temperature, reproduces exactly the characteristic time for SP growth. This suggests that the thermal fluctuations, responsible for SP magnetic moment growth, are also responsible for increasing the recombination probability of SPs. [ABSTRACT FROM AUTHOR]

We present a simple semiclassical model to sustain that in europium chalcogenides (EuX), Faraday rotation (FR) in the transparency gap is proportional to the magnetization of the sample, irrespective of the material's magnetic phase, temperature, or applied magnetic field. The model is validated by FR and magnetization measurements in EuSe in the temperature interval 1.7–300 K, covering all EuSe magnetic phases (paramagnetic, antiferromagnetic type I or type II, ferrimagnetic, and ferromagnetic). Furthermore, by combining the semiclassical model with the explicit electronic energy structure of EuX, the proportionality coefficient between magnetization and FR is shown to be dependent only on the wavelength and the bandgap. Due to its simplicity, the model has didactic value; moreover, it provides a working tool for converting FR into magnetization in EuX. The possible extension of the model to other intrinsic magnetic semiconductors is discussed. [ABSTRACT FROM AUTHOR]

A time-resolved optical pump-probe technique has been applied for studying the ultrafast dynamics in the magnetic semiconductor EuTe near the absorption band gap. We show that application of external magnetic field up to 6 T results in crossover from the inverse Faraday effect taking place on the femtosecond time scale to the optical orientation phenomenon with an evolution in the picosecond time domain. We propose a model which includes both these processes, possessing different spectral and temporal properties. The circularly polarized optical pumping induces the electronic transition 4 f 7 5 d 0 → 4 f 6 5 d 1 forming the absorption band gap in EuTe. The observed crossover is related to a strong magnetic-field shift of the band gap in EuTe at low temperatures. It was found that manipulation of spin states on intrinsic defect levels takes place on a time scale of 19 ps in the applied magnetic field of 6 T. [ABSTRACT FROM AUTHOR]