Search Results (4)

The Observatoire Pérenne de l’Environnement (OPE) station is a rural background site located in North-Eastern France. Besides emissions from agricultural activities, the site is located far from local emissions but at an even distance from the intense emission zones of Western Germany to the north-east and the Paris area to the south-west. In the paper, we report and analyze almost six years of measurements (1 May 2012 to 31 December 2018) of the optical and physical properties of aerosol particles. Based on aerosol optical and physical measurements combined with air mass back-trajectories, we investigate the dependence of these properties on air mass type. Two distinct equivalent black carbon (EBC) sources—origins-fossil fuel (FF) and biomass burning (BB)— were identified. FF was the dominant source of EBC (>70%) but showed a very marked seasonal variation. BB fraction is found higher during the cold seasons in the order of 35% (0.1 µg m⁻³) against 17% (0.05 µg m⁻³) during the warm seasons. The highest EBC and N_0.54–1.15 (particles whose diameter ranged from 0.54 to 1.15 µm) median concentrations were observed during the night time and during the cold seasons compared to the warmer seasons, indicating primary sources trapped within a thin boundary layer (BL). A different behavior is found for N_10–550 (particles whose diameter ranged from 10 to 550 nm) and coarse mode particles (N_1.15–4.5, i.e., particles whose diameter ranged from 1.15 to 4.5 µm) median concentrations, which were observed during the warm seasons compared to the cold seasons, indicating rather biogenic secondary sources for the smaller particles, and potentially primary biogenic sources for the coarse mode particles. The scattering and absorption coefficients and single scattering albedo (SSA) show the same seasonal variations like the ones of N_0.54–1.15 concentrations, indicating that particles larger than 500 nm seemed to contribute the most to the optical properties of the aerosol. Full article

New particle formation (NPF) was predicted to contribute to a major fraction of free tropospheric particle number and cloud condensation nuclei (CCN) concentrations by global models. At high altitudes, pre-existing particle concentrations are low, leading to limited condensational sinks for nucleation precursor gases, and temperatures are cooler compared to lower altitudes, whereas radiation is higher. These factors would all be in favor of nucleation to occur with an enhanced frequency at high altitudes. In the present work, long term data from six altitude stations (and four continents) at various altitudes (from 1465 to 5240 m a.s.l) were used to derive statistically relevant NPF features (frequency, formation rates, and growth rates) and seasonal variability. The combined information together with literature data showed that the frequencies of NPF events at the two Southern hemisphere (SH) stations are some of the highest reported thus far (64% and 67%, respectively). There are indications that NPF would be favored at a preferential altitude close to the interface of the free troposphere (FT) with the planetary boundary layer (PBL) and/or at the vicinity with clouds, which otherwise inhibit the occurrence of NPF. Particle formation rates are found to be lower at high altitudes than at low altitude sites, but a higher fraction of particles are formed via the charged pathway (mainly related to positive ions) compared to boundary layer (BL) sites. Low condensational sinks (CS) are not necessarily needed at high altitudes to promote the occurrence of NPF. For stations at altitudes higher than 1000 m a.s.l., higher CSs favor NPF and are thought to be associated with precursor gases needed to initiate nucleation and early growth. Full article

This study analyzes the relationship between the degrees of resemblance and distances between dialects based on several dialectological atlases. This analysis investigates various correspondence data with respect to total valid data in setting reference places and comparison places. The degree of correspondence (DC) can be calculated by quantifying the degree of resemblance. I adopt a great-circular distance for the distance between the source and a comparison place. It is possible to graph the data with distances and DCs along the X and Y axes, respectively. The analysis yields five main results. (1) DC has an inverse relationship with distance in most places, here called the main sequence. However, there are exceptional places called peculiar groups. (2) One of the peculiar groups was caused by in-migration. (3) Another peculiar group is found on islands having very narrow land areas divided by the sea. (4) The main sequence can be classified into two types of linguistic classes. The grammatical data show a stepping slope instead of a gentle slope in the lexical data. (5) The main sequence shows a precise linear relationship over a narrow area. Full article

This paper discusses the diffusion of two models of mobile learning within the educational research literature: The Framework for the Rational Analysis of Mobile Learning (FRAME) model and the 3-Level Evaluation Framework (3-LEF). The main purpose is to analyse how the two models, now over 10 years old, have been referenced in the literature and applied in research. The authors conducted a systematic review of publications that referenced the seminal papers that originally introduced the models. The research team summarized the publications by recording the abstracts and documenting how the models were cited, described, interpreted, selected, rejected, and/or modified. The summaries were then coded according to criteria such as fields of study, reasons for use, criticisms and modifications. In total, 208 publications referencing the FRAME model and 97 publications referencing the 3-LEF were included. Of these, 55 publications applied the FRAME model and 10 applied the 3-LEF in research projects. The paper concludes that these two models/frameworks were likely chosen for reasons other than philosophical commensurability. Additional studies of the uptake of other mobile learning models is recommended in order to develop an understanding of how mobile learning, as a field, is progressing theoretically. Full article