Modulation of Brain Activity during Action Observation: Influence of Perspective, Transitivity and Meaningfulness

The coupling process between observed and performed actions is thought to be performed by a fronto-parietal perception-action system including regions of the inferior frontal gyrus and the inferior parietal lobule. When investigating the influence of the movements' characteristics on this process, most research on action observation has focused on only one particular variable even though the type of movements we observe can vary on several levels. By manipulating the visual perspective, transitivity and meaningfulness of observed movements in a functional magnetic resonance imaging study we aimed at investigating how the type of movements and the visual perspective can modulate brain activity during action observation in healthy individuals. Importantly, we used an active observation task where participants had to subsequently execute or imagine the observed movements. Our results show that the fronto-parietal regions of the perception action system were mostly recruited during the observation of meaningless actions while visual perspective had little influence on the activity within the perception-action system. Simultaneous investigation of several sources of modulation during active action observation is probably an approach that could lead to a greater ecological comprehension of this important sensorimotor process

An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex

The North American Ice Sheet Complex (NAISC; consisting of the Laurentide, Cordilleran and Innuitian ice sheets) was the largest ice mass to repeatedly grow and decay in the Northern Hemisphere during the Quaternary. Understanding its pattern of retreat following the Last Glacial Maximum is critical for studying many facets of the Late Quaternary, including ice sheet behaviour, the evolution of Holocene landscapes, sea level, atmospheric circulation, and the peopling of the Americas. Currently, the most up-to-date and authoritative margin chronology for the entire ice sheet complex is featured in two publications (Geological Survey of Canada Open File 1574 [Dyke et al., 2003]; ‘Quaternary Glaciations – Extent and Chronology, Part II’ [Dyke, 2004]). These often-cited datasets track ice margin recession in 36 time slices spanning 18 ka to 1 ka (all ages in uncalibrated radiocarbon years) using a combination of geomorphology, stratigraphy and radiocarbon dating. However, by virtue of being over 15 years old, the ice margin chronology requires updating to reflect new work and important revisions. This paper updates the aforementioned 36 ice margin maps to reflect new data from regional studies. We also update the original radiocarbon dataset from the 2003/2004 papers with 1541 new ages to reflect work up to and including 2018. A major revision is made to the 18 ka ice margin, where Banks and Eglinton islands (once considered to be glacial refugia) are now shown to be fully glaciated. Our updated 18 ka ice sheet increased in areal extent from 17.81 to 18.37 million km2, which is an increase of 3.1% in spatial coverage of the NAISC at that time. Elsewhere, we also summarize, region-by-region, significant changes to the deglaciation sequence. This paper integrates new information provided by regional experts and radiocarbon data into the deglaciation sequence while maintaining consistency with the original ice margin positions of Dyke et al. (2003) and Dyke (2004) where new information is lacking; this is a pragmatic solution to satisfy the needs of a Quaternary research community that requires up-to-date knowledge of the pattern of ice margin recession of what was once the world’s largest ice mass. The 36 updated isochrones are available in PDF and shapefile format, together with a spreadsheet of the expanded radiocarbon dataset (n = 5195 ages) and estimates of uncertainty for each interval

Procjena utjecaja modernizacije i novih tehnoloških procesa na izloženost buci u aluminijskoj industriji

The aim of this study was to assess to which extent modernisation of an aluminium production complex reduced occupational noise hazard for jobs with the highest potential of exposure. Periodical measurements of noise level were taken at the same workplaces using the same method, before and after modernisation of all plants. The results were compared with the recommended standard. After modernisation, the noise was significantly reduced in all sections of all plants. The greatest reduction was measured in the foundry. After modernisation, the portion of workplaces with excessive noise level dropped significantly (chi-square=21.315; p<0.0001) from 78.4 % to 13 %. Noise remained a problem in ingot casting and dross skimming section. In the anode plant, noise remained a problem in the green mill section where noise intensities generated by mills and vibrocompactors varied from 95 dB(A) to 102 dB(A). In the electrolysis plant, the portion of workplaces with extensive noise dropped from 77.8 % to 39.3 % after modernisation (p=0.0019). Noise remains to be a problem at the anode covering section where levels rise up to 100 dB(A). The modernisation of the factory has considerably reduced the noise level in the working environment of all plants, but it can not be reduced completely.Cilj je rada procijeniti utjecaj modernizacije tehnološkog procesa proizvodnje aluminija na prisutnost i razinu buke štetne za zdravlje radnika u radnom okolišu. U tu svrhu uspoređivani su rezultati periodičkih mjerenja razine buke prije i nakon modernizacije. Mjerenja intenziteta buke provedena su na istim radnim mjestima i istom metodom tijekom radnih smjena i uspoređeni s važećim nacionalnim standardom. Nakon modernizacije tvornice u svim odjelima proizvodnih pogona značajno se smanjila razina buke, kao i broj radnih mjesta na kojima su radnici izloženi prekomjernoj buci. Najbolji rezultati postignuti su u ljevaonici, gdje se broj radnih mjesta s prekomjernom razinom buke, tj. razinom buke višom od 90 dB(A) smanjio sa 78.4 % na 13 %. Na radnim mjestima gdje se izlijevaju ingoti i skida šljaka buka je i dalje prekomjerna. U pogonu anoda prekomjerna je buka i dalje prisutna pri proizvodnji sirovih anoda, gdje razina buke zbog rada mlinova i vibrokompresora varira od 95 dB(A) do 102 dB(A). U pogonu elektrolize buka viša od 100 dB(A) izmjerena je pri zasipanju anoda. Iako je modernizacijom tvornice i unaprjeđenjem tehnološkog procesa značajno reducirana razina buke, nije ju moguće u cijelosti ukloniti

Contribution à l’étude de l’érosion des berges : analyse à haute résolution spatio-temporelle des mouvements subaériens sur une berge de la rivière Ouelle, Québec, Canada

Trois processus distincts agissant en interrelation contribuent à l’érosion des berges en bordure des cours d’eau : les mouvements de masse, l’érosion fluviale et les mouvements subaériens. Ces derniers résultent de l’effet conjugué des cycles gel-dégel, des cycles d’humidification-dessiccation et de la désagrégation des sédiments par les gouttes de pluie et le ruissellement. Les deux premiers processus érosifs sont les plus connus. Les mouvements subaériens sont moins documentés car ils sont généralement considérés comme un mécanisme préparatoire affaiblissant la berge et facilitant l’érosion par les deux autres processus. Cette étude examine les mouvements subaériens en tant que processus érosifs à l’aide d’observation in situ permettant de décrire et de quantifier leur contribution à l’érosion des berges. Une berge en érosion sur la rivière Ouelle, Québec, a été étudiée à l’aide de levés topographiques mensuels issus d’un LIDAR terrestre (Scan-station II de Leica). Les levés d’une résolution d’1 cm (10 000 points/m2) couvrent une période de dix mois et permettent de suivre l’évolution saisonnière des processus érosifs. Les résultats révèlent que les mouvements subaériens entraînent des épaisseurs d’érosion entre 5 et 50 mm/mois sur l’ensemble de la berge ; l’épaisseur d’érosion variant fortement selon le mois et la position sur la berge. Une analyse qualitative des processus contribuant à l’évolution de la berge a été faite à l’aide d’une série horaire de photographies issues d’une caméra automatisée installée en permanence sur le site. Les variations saisonnières des taux d’érosion liés aux mouvements subaériens ont été mises en relation avec les données météorologiques d’Environnement Canada (2010). Les mouvements subaériens sont plus fréquents lorsque la température oscille autour de zéro. Les mouvements subaériens sont plus que de simples processus préparatoires et que leur contribution à titre d’agent érosif est probablement sous-estimée. Les variations temporelles soulignent l’importance de considérer les saisons dans l’étude de l’érosion des berges pour une meilleure évaluation de l’amplitude et de la fréquence des différents processus d’érosion des berges des cours d’eau.Three types of processes contribute together to riverbank erosion: fluvial erosion, mass failure and subaerial movements produced partly by frost action, wetting and drying cycles and by raindrops and runoff. The first two processes have received far more attention than the latter which are often considered as preparatory processes to bank erosion. In this study, subaerial processes are looked as an eroding agent, in situ measures are carried out in order to document and quantify their contribution to bank erosion. An eroding riverbank on the Ouelle river, Québec, is monitored with a high resolution terrestrial 3D laser scanner (Scan-station II by Leica). Surveys of a resolution of 1 cm (10,000 points/m2) cover a period of ten months and allow us to follow the seasonal evolution of erosion processes. Results show that subaerial movements generate thicknesses of erosion ranging from 5 to 50 mm/month, the thickness of erosion varies depending on the month and the position on the bank Scans are coupled with qualitative analysis of processes contributing to bank face evolution. An automatized camera fixed on the site is used to obtain a photographic series of the riverbank. Meteorological data are examined in relation with the seasonal erosion rates from subaerial movements. Subaerial movements are more frequent when the temperature oscillates around zero. Subaerial movements are more than preparatory processes and that their contribution as erosive agent is likely to be underestimated. Temporal variation underlines the importance of considering seasons for a better evaluation of magnitude and frequency of the contribution of different erosion processes of riverbank