Search results for "Sample"
showing 10 items of 2270 documents
Dataset of a globally relevant stock of soil nitrogen in the Yedoma permafrost domain
2022
This dataset merges nitrogen data from the Yedoma domain. It includes numerous fieldwork campaigns, which take place since 1998. In total 467 samples from the active layer (seasonally thawed layer), 175 samples from perennially frozen Holocene cover deposits, 479 samples from thermokarst deposits in drained thermokarst, 175 in-situ thawed, diagenetically (anaerobic microbial decomposition possible during unfrozen phase) altered Yedoma deposits (called Taberite), and 917 samples from frozen Yedoma deposits are included. Moreover it includes a NH4+ and NO3- quantification basing on of 658 samples, including 378 data points for NH4+ (active layer, 93; Holocene cover, 108; thermokarst sediment,…
Análisis de materiales didácticos digitales para guiar y/o apoyar el proceso de enseñanza - aprendizaje de las matemáticas
2018
Las tecnologías digitales han supuesto una revolución en todos los ámbitos de la vida: tecnológico, empresarial, comunicativo, cultural, e incluso en el conocimiento y el entretenimiento. En el panorama educativo tiene también su reflejo y las metodologías y recursos se han redibujado, en cuanto a los diferentes soportes, canales, lenguajes, narrativas,? Estos cambios, sustantivos y profundos, afectan simultáneamente al profesorado, alumnado y familias, pero otros agentes como las administraciones educativas y el sector editorial también se ve involucrado. En esta investigación analizamos una muestra de portales institucionales y plataformas comerciales que ofertan recursos didácticos digit…
The status of dental caries and related factors in a sample of Iranian adolescents.
2010
Objective: To describe the status of dental caries in a sample of Iranian adolescents aged 14 to 18 years in Qazvin, and to identify caries-related factors affecting this group. Study design: Qazvin was divided into three zones according to socio-economic status. The sampling procedure used was a stratified cluster sampling technique; incorporating 3 stratified zones, for each of which a cluster of school children were recruited from randomly selected high schools. The adolescents agreed to participate in the study and to complete a questionnaire. Dental caries status was assessed in terms of decayed teeth (DT), filled teeth (FT) and decayed, missing and filled teeth (DMFT). A multivariate …
Economic and Technical Efficiency of Drinking Water Systems: An Empirical Approach for Spain
2009
The objective of this paper is to analyze the efficiency of drinking water systems. Efficient performance, both in technical and economic terms guarantee minimum water losses in the network and reduced tariffs for the users. An analytical benchmarking methodology based on non-radial measures considering water losses as undesirable output gives us an efficiency indicator for each input used in the water supply process. These indicators, obtained by means of mathematical programming techniques, are used to rank suppliers' activity. The relation between the efficiency in the activity of the companies and the establishment of different tariffs is also analyzed. An empirical application is carry…
Standardizing the use of fast-field cycling NMR relaxometry for measuring hydrological connectivity inside the soil
2019
Hydrological connectivity inside the soil (HCS) is applied to study the effects of heterogeneities in complex environmental systems. It refers to both the spatial patterns inside the soil (i.e., structural connectivity [SC]) and the physical–chemical processes at a molecular level (i.e., functional connectivity [FC]). NMR relaxometry has been already applied to assess both SC and FC components of the HCS by defining SC and FC indexes. Here, fast-field cycling NMR relaxometry has been applied on a water suspended soil and a sediment to optimize the conditions to standardize the technique. Proton Larmor frequencies (ωL) from 0.01 to 25 MHz were used on samples suspended in three different rat…
Unbiased Simultaneous Prediction Limits on Observations in Future Samples
2013
This paper provides procedures for constructing unbiased simultaneous prediction limits on the observations or functions of observations of all of k future samples using the results of a previous sample from the same underlying distribution belonging to invariant family. The results have direct application in reliability theory, where the time until the first failure in a group of several items in service provides a measure of assurance regarding the operation of the items. The simultaneous prediction limits are required as specifications on future life for components, as warranty limits for the future performance of a specified number of systems with standby units, and in various other app…
Relative evaluation of regression tools for urban area electrical energy demand forecasting
2019
Abstract Load forecasting is the most fundamental application in Smart-Grid, which provides essential input to Demand Response, Topology Optimization and Abnormally Detection, facilitating the integration of intermittent clean energy sources. In this work, several regression tools are analyzed using larger datasets for urban area electrical load forecasting. The regression tools which are used are Random Forest Regressor, k-Nearest Neighbour Regressor and Linear Regressor. This work explores the use of regression tool for regional electric load forecasting by correlating lower distinctive categorical level (season, day of the week) and weather parameters. The regression analysis has been do…
Environmental sustainability in hotels: a matter of category?
2012
As in other economic activities, companies in the hospitality industry have proposed several practices and implemented technology solutions to pursue environmental sustainability of their activities and minimise their impact on climate change. Some applications of information and communication technologies (ICT) may contribute to the reduction of the demand of supplies, water and energy by hotels. In the present paper, we aim at exploring the influence of the hotel category on the implementation of environmental-friendly technologies in hotels. Considering a sample of Spanish hotels in the most important cities, we evaluate the relationship between the level of implementation of certain tec…
Quantitative Estimation of Major and Trace Elements in Coals of the Benue Trough, Nigeria
2013
The concentrations of major and trace elements in ash residues of coals of the Benue Trough, Nigeria have been determined by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry, respectively. Major and trace element determination in rocks by fusion on an iridium strip heater followed by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry is extended here to coal ash, and the accuracy of the method is evaluated by including an Argonne Premium Coal reference sample in each analysis program. Si and Al are the major elements detected in the coal ashes. An assessment using worldwide concentration ranges of trace elements in coal ash…
Chemical separation and MC-ICPMS analysis of U, Th, Pa and Ra isotope ratios of carbonates
2018
Diagenetic alteration of fossil reef corals may have severe effects on the reliability of 230Th/U-ages. The widely applied criteria introduced to test for the reliability of coral 230Th/U-ages are often not sufficient to identify all altered ages. The combination of 230Th/U- with 231Pa/U-dating has been suggested as a promising method to identify altered ages. Furthermore, 226Ra/230Th ratios can provide information about the diagenetic history during the last 10 000 years. Here we present a method to chemically separate U, Th, Pa and Ra from the same aliquot of a carbonate sample. The isotope ratios of our mixed U–Th–Pa–Ra spike are calibrated using a secular equilibrium material treated in…