837 research outputs found

    Convolutional Goppa Codes

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    We define Convolutional Goppa Codes over algebraic curves and construct their corresponding dual codes. Examples over the projective line and over elliptic curves are described, obtaining in particular some Maximum-Distance Separable (MDS) convolutional codes.Comment: 8 pages, submitted to IEEE Trans. Inform. Theor

    Transfer parameters for ICRP's Reference Animals and Plants in a terrestrial Mediterranean ecosystem

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    A system for the radiological protection of the environment (or wildlife) based on Reference Animals and Plants (RAPs) has been suggested by the International Commission on Radiological Protection (ICRP). To assess whole-body activity concentrations for RAPs and the resultant internal dose rates, transfer parameters are required. However, transfer values specifically for the taxonomic families defined for the RAPs are often sparse and furthermore can be extremely site dependent. There is also a considerable geographical bias within available transfer data, with few data for Mediterranean ecosystems. In the present work, stable element concentrations (I, Li, Be, B, Na, Mg, Al, P, S, K. Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Cs, Ba, Tl, Pb and U) in terrestrial RAPs, and the corresponding whole-body concentration ratios, CRwo, were determined in two different Mediterranean ecosystems: a Pinewood and a Dehesa (grassland with disperse tree cover). The RAPs considered in the Pinewood ecosystem were Pine Tree and Wild Grass; whereas in the Dehesa ecosystem those considered were Deer, Rat, Earthworm, Bee, Frog, Duck and Wild Grass. The CRwo values estimated from these data are compared to those reported in international compilations and databases

    Efficiency of university education: A partial frontier analysis

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    This article investigates the efficiency of the university education using two linked databases (Saber Pro and Saber 11) from the Colombian Institute for Evaluation of Education (ICFES) corresponding to 2014. We use a non-parametric frontier approach that combines the "order m" technique with the concept of a meta-frontier to disaggregate students' total efficiency in generic skills in quantitative reasoning, critical reading, and written communication, into the parts attributable to the students themselves and the university. The analysis is performed by academic programme and by education sector (public vs. private). Results indicate that most of the inefficiency of students in the assessment of generic skills in higher education is attributable to the students themselves and a significant number of students could improve their performance in the assessment in each of the academic programmes if they performed as efficiently as those located on the frontier. Furthermore, the inefficiency share of students varies between academic programmes and university sectors, with students in the private sector more inefficient than those in the public sector in some and less inefficient in others. This research constitutes the first application of the technique of "order m" with the approach of the meta-frontier for the analysis of educational efficiency using data at the student and university levels
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