Longitudinal spectra of wind velocity in the atmospheric surface layer perturbed by a small topographic ridge

Turbulence measurements carried out in the near neutral surface layer are presented. The wind velocity components were measured with sonic anemometers at 2 and 10 m height. Three masts are considered, placed about 4 km upwind, on the top and about 6 km downwind of Inexpressible Island, a relief 300 m high and 1 km in cross-section. Spectral features are discussed in detail. Local equilibrium is found in the inertial subrange and in (at least in part of) the intermediate range, characterized by different slopes upwind and downwind (k−1 and k−5/3, respectively) for the components parallel to the terrain

The relationship betweens math anxiety and arithmetic reasoning: The mediating role of working memory and self-competence

The complex interplay between cognitive and emotional factors at the base of maths achievement started to be evaluated and quantified in the last few years. Only a few studies, anyway, examine at the same time, the role of working memory (visuospatial and verbal subsystem) and maths anxiety together with self-competence, on maths attainment. To investigate the specific link between these three factors, in a large developmental sample, we enrol 335 students from the 3rd, 5th, and 7th grades. In respect to emotional and motivational factors, data indicates a direct influence of maths anxiety on maths performance. Furthermore, the results highlight that maths anxiety differently impacts working memory subsystems. In fact, we observe a significant and indirect effect of MA, through the visuospatial system, on maths achievement. Our results provide further support to the hypothesis that maths anxiety is a special type of anxiety, most likely impacting the visuospatial rather than the verbal working memory subsystem. Data is discussed in terms of a possible mechanism underlying maths anxiety and visuospatial working memory at the base of this specificity, and in relation to the role of self-competence in this interplay

Plant mediated methane efflux from a boreal peatland complex

Purpose Aerenchymous plants are an important control for methane efflux from peatlands to the atmosphere, providing a bypass from the anoxic peat and avoiding oxidation in the oxic peat. We aimed to quantify the drivers of aerenchymous peatland species methane transport and the importance of this process for ecosystem-scale methane efflux. Methods We measured seasonal and interspecies variation in methane transport rate per gram of plant dry mass at a boreal fen and bog, which were upscaled to ecosystem-scale plant methane transport. Results Methane transport rate was better explained by plant species, leaf greenness and area than by environmental variables. Leaves appeared to transport methane even after senescence. Contrary to our expectations, both methane transport rate and the proportion of plant transport were lower in the fen (with greater sedge cover) than in the bog site. At the fen and bog, average methane transport rate was 0.7 and 1.8 mg g(-1) d(-1), and the proportion of seasonally variable plant transport was 7-41% and 6-90%, respectively. Species-specific differences in methane transport rate were observed at the ecosystem-scale: Scheuchzeria palustris, which accounted for 16% of the aerenchymous leaf area in the fen and displayed the greatest methane transport rate, was responsible for 45% of the ecosystem-scale plant transport. Conclusion Our study showed that plant species influence the magnitude of ecosystem-scale methane emissions through their properties of methane transport. The identification and quantification of these properties could be the pivotal next step in predicting plant methane transport in peatlands.Peer reviewe

Noise, age and gender effects on speech intelligibility and sentence comprehension for 11- to 13-year-old children in real classrooms.

The present study aimed to investigate the effects of type of noise, age, and gender on children\u2019s speech intelligibility (SI) and sentence comprehension (SC). The experiment was conducted with 171 children between 11 and 13 years old in ecologically-valid conditions (collective presentation in real, reverberating classrooms). Two standardized tests were used to assess SI and SC. The two tasks were presented in three listening conditions: quiet; traffic noise; and classroom noise (non-intelligible noise with the same spectrum and temporal envelope of speech, plus typical classroom sound events). Both task performance accuracy and listening effort were considered in the analyses, the latter tracked by recording the response time (RT) using a single-task paradigm. Classroom noise was found to have the worst effect on both tasks (worsening task performance accuracy and slowing RTs), due to its spectro-temporal characteristics. A developmental effect was seen in the range of ages (11\u201313 years), which depended on the task and listening condition. Gender effects were also seen in both tasks, girls being more accurate and quicker to respond in most listening conditions. A significant interaction emerged between type of noise, age and task, indicating that classroom noise had a greater impact on RTs for SI than for SC. Overall, these results indicate that, for 11- to 13-year-old children, performance in SI and SC tasks is influenced by aspects relating to both the sound environment and the listener (age, gender). The presence of significant interactions between these factors and the type of task suggests that the acoustic conditions that guarantee optimal SI might not be equally adequate for SC. Our findings have implications for the development of standard requirements for the acoustic design of classrooms

Intuitive geometry and visuospatial working memory in children showing symptoms of nonverbal learning disabilities.

Visuospatial working memory (VSWM) and intuitive geometry were examined in two groups aged 11-13, one with children displaying symptoms of nonverbal learning disability (NLD; n = 16), and the other, a control group without learning disabilities (n = 16). The two groups were matched for general verbal abilities, age, gender, and socioeconomic level. The children were presented with simple storage and complex-span tasks involving VSWM and with the intuitive geometry task devised by Dehaene, Izard, Pica, and Spelke (2006 ). Results revealed that the two groups differed in the intuitive geometry task. Differences were particularly evident in Euclidean geometry and in geometrical transformations. Moreover, the performance of NLD children was worse than controls to a larger extent in complex-span than in simple storage tasks, and VSWM differences were able to account for group differences in geometry. Finally, a discriminant function analysis confirmed the crucial role of complex-span tasks involving VSWM in distinguishing between the two groups. Results are discussed with reference to the relationship between VSWM and mathematics difficulties in nonverbal learning disabilities

Methane Fluxes Into Atmosphere from Fennoskandian Lakes

The experimental data on methane fluxes into the atmosphere from Fennoscandian lakes is analyzed. The contribution made by the lake network of this northern region to the atmospheric methane budget is estimated as 320 +/- 23 KtCH(4) per year. From 16 to 37% of the annual methane emission from Fennoscandian lakes is carried out by methane produced during the ice cover period. The methane fluxe rate from studied lakes is estimated as 2.6 +/- 0.2 gCH(4)m(-2) yr(-1). Among lakes of the region, small lakes (areaPeer reviewe

Lake-atmosphere interactions at Alqueva reservoir : a case study in the summer of 2014

The study of lake-atmosphere interactions was the main purpose of a 2014 summer experiment at Alqueva reservoir in Portugal. Near-surface fluxes of momentum, heat and mass [water vapour (H2O) and carbon dioxide (CO2)] were obtained with the new Campbell Scientific's IRGASON Integrated Open-Path CO2/H2O Gas Analyser and 3D Sonic Anemometer between 2 June and 2 October. On average, the reservoir was releasing energy in the form of sensible and latent heat flux during the study period. At the end of the 75 d, the total evaporation was estimated as 490.26 mm. A high correlation was found between the latent heat flux and the wind speed (R = 0.97). The temperature gradient between air and water was positive between 12 and 21 UTC, causing a negative sensible heat flux, and negative during the rest of the day, triggering a positive sensible heat flux. The reservoir acted as a sink of atmospheric CO2 with an average rate of -0.026 mg m(-2) s(-1). However, at a daily scale we found an unexpected uptake between 0 and 9 UTC and almost null flux between 13 and 19 UTC. Potential reasons for this result are further discussed. The net radiation was recorded for the same period and water column heat storage was estimated using water temperature profiles. The energy balance closure for the analysed period was 81%. In-water solar spectral downwelling irradiance profiles were measured with a new device allowing measurements independent of the solar zenith angle, which enabled the computation of the attenuation coefficient of light in the water column. The average attenuation coefficient for the photosynthetically active radiation spectral region varied from 0.849 +/- 0.025 m(-1) on 30 July to 1.459 +/- 0.007 m(-1) on 25 September.Peer reviewe

Challenges for evaluating process-based models of gas exchange at forest sites with fetches of various species

Physiologically-based (or process-based) models are commonly applied to describe plant responses mechanistically in dependence on environmental conditions. They are increasingly evaluated with eddy-covariance measurements that integrate carbon and water exchange of an area of several hectares (called the fetch). However, almost all models applied to date in such exercises have considered only the dominant tree species and neglected other species that contributed to the measured gas exchange rates-either in separate patches or in mixture. This decreases the transferability of the model from one site to another because the contributions from other species might be different. It is therefore a major challenge in modeling today to separate the measured gas exchanges by sources. In this study, a detailed physiologically-based biosphere model is applied that allows distinguishing between tree species in mixed forests, considering them as «vegetation cohorts» that interact with each other. The sensitivity of the model to different assumptions about how different tree species contribute to an integrated measurement of standscale gas exchange is investigated. The model exercise is carried out for a forest site in Finland with dominant Scots pine but presence of significant amounts of Norway spruce and birch. The results demonstrate that forest structure affects simulated gas exchange rates indicating a possible importance of considering differences in physiological properties at the species level. It is argued that the variation of stand structure within the range of eddy-covariance measurements should be better accounted for in models and that inventory measurements need to consider this variation

Challenges for evaluating process-based models of gas exchange at forest sites with fetches of various species

Peer reviewe