Accuracy of Rats in Discriminating Visual Objects Is Explained by the Complexity of Their Perceptual Strategy

Despite their growing popularity as models of visual functions, it remains unclear whether rodents are capable of deploying advanced shape-processing strategies when engaged in visual object recognition. In rats, for instance, pattern vision has been reported to range from mere detection of overall object luminance to view-invariant processing of discriminative shape features. Here we sought to clarify how refined object vision is in rodents, and how variable the complexity of their visual processing strategy is across individuals. To this aim, we measured how well rats could discriminate a reference object from 11 distractors, which spanned a spectrum of image-level similarity to the reference. We also presented the animals with random variations of the reference, and processed their responses to these stimuli to derive subject-specific models of rat perceptual choices. Our models successfully captured the highly variable discrimination performance observed across subjects and object conditions. In particular, they revealed that the animals that succeeded with the most challenging distractors were those that integrated the wider variety of discriminative features into their perceptual strategies. Critically, these strategies were largely preserved when the rats were required to discriminate outlined and scaled versions of the stimuli, thus showing that rat object vision can be characterized as a transformation-tolerant, feature-based filtering process. Overall, these findings indicate that rats are capable of advanced processing of shape information, and point to the rodents as powerful models for investigating the neuronal underpinnings of visual object recognition and other high-level visual functions

A Multi-Year Study of Radioactivity in Surface Air and Its Relation to Climate Variables in Belgrade, Serbia

Activities of Be-7 and Pb-210 were monitored in surface air in Belgrade, Serbia, from 2004 to 2012. The measurements were taken from two locations, in an open field of a city suburb and in the central city area. The activities were determined on HPGe detectors by standard gamma spectrometry. The Be-7 activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter, while the Pb-210 activity exhibits two maxima, in autumn and late winter. The mean monthly concentrations measured at both sites are below 9 mBq/m(3) and 1.3 mBq/m(3) for Be-7 and Pb-210, respectively. The obtained correlation of the Be-7 activity with the number of sun-spots is not statistically significant. Relations of the radionuclides activities with climate variables (precipitation, temperature, relative humidity, cloud cover, sunshine hours, and atmospheric pressure) are also investigated, but the only significant correlations are found for the Be-7 activity with temperature and sunshine hours, and the Pb-210 activity with atmospheric pressure. The maximum Be-7 and Pb-210 activities corresponding to binned total monthly precipitation data imply different modes of the radionuclide scavenging from the atmosphere. During dry periods, accumulation of the radionuclides in the atmosphere leads to their increased activities, but no correlation was found between the activities and the number of consecutive dry days

The worldwide C3S CORDEX grand ensemble: A major contribution to assess regional climate change in the IPCC AR6 Atlas

peer reviewedAbstract The collaboration between the Coordinated Regional Climate Downscaling Experiment (CORDEX) and the Earth System Grid Federation (ESGF) provides open access to an unprecedented ensemble of Regional Climate Model (RCM) simulations, across the 14 CORDEX continental-scale domains, with global coverage. These simulations have been used as a new line of evidence to assess regional climate projections in the latest contribution of the Working Group I (WGI) to the IPCC Sixth Assessment Report (AR6), particularly in the regional chapters and the Atlas. Here, we present the work done in the framework of the Copernicus Climate Change Service (C3S) to assemble a consistent worldwide CORDEX grand ensemble, aligned with the deadlines and activities of IPCC AR6. This work addressed the uneven and heterogeneous availability of CORDEX ESGF data by supporting publication in CORDEX domains with few archived simulations and performing quality control. It also addressed the lack of comprehensive documentation by compiling information from all contributing regional models, allowing for an informed use of data. In addition to presenting the worldwide CORDEX dataset, we assess here its consistency for precipitation and temperature by comparing climate change signals in regions with overlapping CORDEX domains, obtaining overall coincident regional climate change signals. The C3S CORDEX dataset has been used for the assessment of regional climate change in the IPCC AR6 (and for the interactive Atlas) and is available through the Copernicus Climate Data Store (CDS)

Future climate change impacts on residential heating and cooling degree days in Serbia

This study analyzes the potential changes of residential heating and cooling degree days (HDD and CDD) in the 21st century over Serbia with the regional climate model (RCM) EBU-POM under two different forcing scenarios (A1B and A2). The validation of the model shows that the model reproduces the spatial variability, magnitude, and annual cycles of HDD and CDD for the reference period very well. According to both scenarios, a significant decrease of HDD and increase of CDD is expected all over Serbia. The simulations show a spatial heterogeneity in the potential changes, with the largest decrease of HDD in southern (mountainous) Serbia and largest increase of CDD in northern (lowland) Serbia. Results also show that by the end of the 21st century, the existing ratio between populations weighted regional mean CDD and HDD of 1:7.3 could be reduced to 1:2.3 according to the A1B scenario and 1:2.0 according to the A2 scenario. At the end of the 21st century cooling season length will be for about two times longer than at the reference period, while length of the heating season will be reduced for about 25%. According to both scenarios model projected an increase of the heating and cooling season temperature through 21st century by slightly less than 2 °C. Our study is the first research of future changes in HDD and CDD over Serbia based on regional climate modeling. Results of the research should help the policy of energy management and planning through provided indications of future spatial and seasonal changes of HDD and CDD within Serbia

Factors affecting the 7Be surface concentration and its extremely high occurrences over the Scandinavian Peninsula during autumn and winter

Relationships between the beryllium-7 concentrations in surface air and meteorological parameters (temperature, atmospheric pressure, and precipitation), teleconnection indices (Arctic Oscillation, North Atlantic Oscillation, and Scandinavian pattern) and number of sunspots are investigated using two multivariate statistical techniques: hierarchical cluster and factor analysis. The beryllium-7 surface measurements over 1995-2011, at four sampling sites located in the Scandinavian Peninsula, are obtained from the Radioactivity Environmental Monitoring Database. In all sites, the statistical analyses show that the beryllium-7 concentrations are strongly linked to temperature. Although the beryllium-7 surface concentration exhibits the well-characterised spring/summer maximum, our study shows that extremely high beryllium-7 concentrations, defined as the values exceeding the 90th percentile in the data records for each site, also occur over the October-March period. Two types of autumn/winter extremes are distinguished: type-1 when the number of extremes in a given month is less than three, and type-2 when at least three extremes occur in a month. Factor analysis performed for these autumn/winter events shows a weaker effect of temperature and a stronger impact of the transport and production signal on the beryllium-7 concentrations. Further, the majority of the type-2 extremes are associated with a very high monthly Scandinavian teleconnection index. The type-2 extremes that occurred in January, February and March are also linked to sudden stratospheric warmings of the Arctic vortex. Our results indicate that the Scandinavian teleconnection index might be a good indicator of the meteorological conditions facilitating extremely high beryllium-7 surface concentrations over Scandinavia during autumn and winter.JRC.G.10-Knowledge for Nuclear Security and Safet

Beryllium-7 surface concentration extremes in Europe

Seasonal and spatial patterns of extremely high beryllium-7 surface concentration recorded over the 2001–2010 period across Europe are investigated. The beryllium-7 measurements for 14 sites are taken from the Radioactivity Environmental Monitoring Database. An investigation of the annual cycles of the beryllium-7 surface concentration shows that their maximum and minimum values occur later in the year as the latitude of the measurement site decreases. Extremely high beryllium-7 surface concentrations are defined here as values greater than the 95th percentile in each measurement site. Most of the extremes occur over the March–August period. At least 10 % of the total number of extremes appear during autumn and winter, with an exception of Vienna, where all the extremes took place during spring and summer. The regional spread of extremes common for pairs of measurement sites points to an existence of three distinct regions in Europe: north of 55 °N, between 45 °N and 55 °N, and south of 45 °N. Although the beryllium-7 concentration records are significantly correlated across all the investigated sites, the strongest correlations are found within the identified regionsJRC.G.10-Knowledge for Nuclear Security and Safet

ANALYSIS OF EXTREME BERYLLIUM-7 SPECIFIC ACTIVITIES IN SURFACE AIR

We present an analysis of the maxima in a large dataset of the beryllium-7 specific activities measured in surface air in Helsinki, Finland, over 25 years (1987-2011), which are stored in the online Radioactivity Environmental Monitoring (REM) database. The maxima are defined as events with the beryllium-7 specific activity above the 95th percentile, which, for the Helsinki data set, equals to 4.82\u9710-3 Bq\u97m-3. The beryllium-7 specific activity in Helsinki shows a seasonal pattern with the monthly means above 2.00\u9710-3 Bq\u97m-3 during the warm season (April– September), and below 2.00\u9710-3 Bq\u97m-3 during the cold season (October–March). The analysis of the extremes shows that 10 % occurred in the cold season, and these “cold extremes” are analysed in more detail. Amongst the cold extremes, three representative “episodes” are identified. The episodes, which occurred in March 1999, February 2003 and February 2005, show extremely high beryllium-7 specific activities measured over several consecutive days. Anomalies of potential vorticity, sea level pressure and surface temperature, as well as precipitation, over Europe and the Atlantic are investigated. A brief analysis of one cold extreme, classified as “burst” since it was an isolated event surrounded by measurements below the 95th percentile, is also presented in an attempt to find common mechanisms that contribute to both cold extreme episodes and bursts. Scandinavia teleconnection index seems to represent a good indicator of potentiall

Factors affecting the 7Be surface concentration and its extremely high occurrences over the Scandinavian Peninsula during autumn and winter

Relationships between the beryllium-7 concentrations in surface air and meteorological parameters (temperature, atmospheric pressure, and precipitation), teleconnection indices (Arctic Oscillation, North Atlantic Oscillation, and Scandinavian pattern) and number of sunspots are investigated using two multivariate statistical techniques: hierarchical cluster and factor analysis. The beryllium-7 surface measurements over 1995-2011, at four sampling sites located in the Scandinavian Peninsula, are obtained from the Radioactivity Environmental Monitoring Database. In all sites, the statistical analyses show that the beryllium-7 concentrations are strongly linked to temperature. Although the beryllium-7 surface concentration exhibits the well-characterised spring/summer maximum, our study shows that extremely high beryllium-7 concentrations, defined as the values exceeding the 90th percentile in the data records for each site, also occur over the October-March period. Two types of autumn/winter extremes are distinguished: type-1 when the number of extremes in a given month is less than three, and type-2 when at least three extremes occur in a month. Factor analysis performed for these autumn/winter events shows a weaker effect of temperature and a stronger impact of the transport and production signal on the beryllium-7 concentrations. Further, the majority of the type-2 extremes are associated with a very high monthly Scandinavian teleconnection index. The type-2 extremes that occurred in January, February and March are also linked to sudden stratospheric warmings of the Arctic vortex. Our results indicate that the Scandinavian teleconnection index might be a good indicator of the meteorological conditions facilitating extremely high beryllium-7 surface concentrations over Scandinavia during autumn and winter.JRC.G.10-Knowledge for Nuclear Security and Safet