Search results for "CORR"
showing 10 items of 6535 documents
La non stationnarité dans les séries saisonnières. Application au tourisme tunisien
1998
The purpose of the paper is to specify the nature of the seasonal behaviors of tourist stay demand in Tunisia by using recent tools of monthly time series analysis. The available series (tourist expenditures, prices, guest nights, reception capacities,...) are analyzed with the classical theory of demand and the theory of supply induced demand. Empirical results show that these series are generated by non stationary processes which seasonality is stochastic and deterministic. The extent of the maximum likelihood method proposed by Lee (1992) for monthly data emphasizes unit roots and cointegration relationships at some seasonal frequencies. Error correction models are derived for endogenous…
Can arbuscular mycorrhizal fungi enhance plant nitrogen capture from organic matter added to soil?
2012
Relaciones suelo-vegetación en una toposecuencia del Escudo Guayanés, Venezuela
2014
El Escudo Guayanés es uno de los territorios más antiguos del planeta; tiene millones de años sometido a procesos de lixiviación y erosión que dejan suelos oligotróficos. El objetivo de este trabajo fue hacer la caracterización de los parámetros físicos y químicos de los suelos, en diferentes comunidades boscosas de la Reserva Forestal Imataca, e identificar ciertas relaciones entre los componentes edáficos y las especies que allí se presentan. Se realizó un inventario de todos los individuos mayores a 10cm dap (diámetro a la altura del pecho) en 15 parcelas (1ha); en cada una de esas parcelas se evaluaron cuatro sub-parcelas de sotobosque (100m²) para contabilizar todas las espermatofitas;…
ICAnDoiT: the impact of computerised adaptive corrective feedback on L2 English learners
2016
The present dissertation examines the impact of (computerised) adaptive corrective feedback, that is, feedback dynamically adapting to learners’ abilities, in English as a second/foreign language (L2) and explores the ways to maximise this impact. The study was inspired by the sociocultural perspective on development, which had implications for the interpretation of the results, including those obtained through statistical data analyses. The dissertation comprises five articles and a synthesis. In the first article, a positive effect of adaptive corrective feedback on the learners’ ability to formulate L2 English wh-questions is established. The second article explores how learners’ beliefs…
Symbolisme phonétique et transmodalité
2019
Spatial spillovers in France: a study on individual count data at the city level
2007
Our study aims to measure the effects of spatial R&D spillovers on firms' patent production at the city level. We use an original method to estimate the spatial dimension of spillovers using count data. The method, based on a generalized cross entropy approach, allows us to test spatial auto-correlation. The main result is that when there are local spillovers, their impact on knowledge production is different according to the geographical area and the sector.
Spatial analysis of the Italian seismic network and seismicity
2018
Seismic networks are powerful tools for understanding active tectonic processes in a monitored region. Their numerous applications, from monitoring seismicity to characterizing seismogenic volumes and generated seismicity, make seismic networks essential tools for assessing seismic hazard in active regions. The ability to locate earthquakes hypocenters requires a seismic network with a sufficient number of optimally distributed, stations. It is important to assess existing network geometry, to identify seismogenic volumes that are not adequately monitored, and to quantify measures that will allow network improvement. In this work we have studied the spatial arrangement of the stations of th…
Probabilistic and preferential sampling approaches offer integrated perspectives of Italian forest diversity
2023
Aim: Assessing the performances of different sampling approaches for documenting community diversity may help to identify optimal sampling efforts and strategies, and to enhance conservation and monitoring planning. Here, we used two data sets based on probabilistic and preferential sampling schemes of Italian forest vegetation to analyze the multifaceted performances of the two approaches across three major forest types at a large scale. Location: Italy. Methods: We pooled 804 probabilistic and 16,259 preferential forest plots as samples of vascular plant diversity across the country. We balanced the two data sets in terms of sizes, plot size, geographical position, and vegetation types. F…
Joint second-order parameter estimation for spatio-temporal log-Gaussian Cox processes
2018
We propose a new fitting method to estimate the set of second-order parameters for the class of homogeneous spatio-temporal log-Gaussian Cox point processes. With simulations, we show that the proposed minimum contrast procedure, based on the spatio-temporal pair correlation function, provides reliable estimates and we compare the results with the current available methods. Moreover, the proposed method can be used in the case of both separable and non-separable parametric specifications of the correlation function of the underlying Gaussian Random Field. We describe earthquake sequences comparing several Cox model specifications.
Seasonal variation in diversity of marine benthic invertebrates leads to a positive species-genetic diversity correlation (SGDC)
2018
Species-genetic diversity correlations (SGDCs) are useful indicators of processes that simultaneously affect diversity at multiple biological levels. We combined spatial and temporal sampling of 4 study sites in the Danish Isefjord-Roskilde Fjord Estuary at 4 time points over 1 yr to investigate the effect of seasonal variation on SGDCs. Species diversity was estimated as species richness from samples comprising 20752 individuals representing 51 benthic invertebrate taxa. Genetic diversity was estimated for a single focal taxon, the polychaete Pygospio elegans, as mean allelic richness at 7 microsatellite loci. Combining all samples, a significant positive correlation between species richne…