130,828 research outputs found
Increasing classroom engagement and student comprehension through the use of clickers: an Italian secondary school experience
No full text"Clickers" are individual response devices that allow each student to respond to questions presented by teachers. This technology promises to be beneficial since it increases student engagement and provides prompt feedback - two key practices that stimulate learning. Although a number of researchers have studied clickers in higher education and in large classroom settings, there has been very little research in small classrooms and at lower levels. Our research has investigated the role of clickers in five different classes of an Italian grade one secondary school. Two different situations of interactive teaching were compared. In both cases, teachers pose a variety of questions during the course of the explanation, but in the first situation they received answers by “hand-raising”, in the second situation through the electronic devices. We wanted to verify differences posed by the use of technology regarding: a) learning outcomes, b) student engagement, c) student’s evaluation regarding learning conditions. Results are consistent with other research, which forecasts that students are more cognitively engaged while using clickers; however data showed unexpected differences in learning outcomes based on the subject matter
Comments on the Cosmological Horizon Problem
No full textCurrent attempts to find a solution to the problem of the cosmological particle horizon are reviewed with reference to two general approaches. The first approach involves modifications to the standard theory in the very early Universe, close to the Planck time, whereas the second approach tries to exploit new developments in elementary particle physics in such a way as to eliminate the problem at much later times. The relative merits and demerits of the two approaches are examined and it is suggested that the resolution of the cosmological horizon problem be sought in processes occuring at or near the Planck epoch
Transitory L-carnitine depletion in rat skeletal muscle by D-carnitine
No full textWeanling and adult rats were intraperitoneally injected with d-carnitine for 40 days. After 15 days of treatment a statistically significant depletion in the muscle levels of free and total l-carnitine was observed, but after 40 days this depletion became slight and statistically not significant. These findings suggest the presence of a compensatory mechanism acting on the inhibition of l-carnitine transport into skeletal muscle fibres. © 1989
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of oxygen reduction on the optical conductivity of La0.75Ca0.25MnO3
No full textReflectivity measurements are used to obtain the optical conductivity of three La0.75Ca0.25MnO32y samples annealed under increasingly strong reducing conditions. All three samples are nearly saturated ferromagnets although their Curie temperatures fall progressively from Tc5221 K to Tc5187 K with maximum deoxygenation. The presence of Drude absorption indicates that the unreduced and the slightly reduced samples are electrical conductors below Tc . However, the most reduced sample manifests an insulatinglike optical conductivity at all temperatures. Thus, ferromagnetism and insulating behavior coexist in the most-reduced sample. This result contradicts the notion that mobile charge carriers of an electrically conducting manganite induce its ferromagnetism. Beyond Drude absorption, midinfrared and near-infrared absorptions are also observed. A midinfrared absorption band is present in all samples. The energy at its peak falls markedly with decreasing temperature. Moreover, near-infrared absorption is found in the nonconducting sample and in the high-temperature insulating phase of the conducting samples. The implications of these findings are discussed in terms of models for properties of doped manganites
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Black diamond for solar energy conversion
No full textBlack diamond is obtained by a controlled nanoscale periodic texturing of CVD diamond surface, able to drastically modify the interaction with solar radiation from optical transparency up to solar absorptance values even >90%. Surface texturing, performed by the use of an ultra-short pulse laser, is demonstrated to induce an intermediate band within the diamond bandgap supporting an efficient photoelectronic conversion of sub-bandgap photons (<5.5 eV). The intermediate band introduction results in an external quantum efficiency enhanced up to 800 nm wavelengths (and up two orders of magnitude larger than the starting transparent diamond film), without affecting the film transport capabilities. The optical and photoelectronic outstanding results open the path for future application of black diamond as a photon-enhanced thermionic emission cathode for solar concentrating systems, with advantages of excellent electronic properties combined with a potentially very low work function and high thermal stability
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