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"Grid cells"

Siliang Lin, Yaozhu Jiang, Jiekun He, Guangzhi Ma, Yang Xu, Haisheng Jiang
The study of the past, present, and future state and dynamics of the tropical natural forest cover (NFC) might help to better understand the pattern of deforestation and fragmentation as well as the influence of social and natural processes. The obtained information will support the development of effective conservation policies and strategies. In the present study, we used historical data of the road network, topography, and climatic productivity to reconstruct NFC maps of Hainan Island, China, from the 1950s to the 2010s, using the random forest algorithm...
2017: PeerJ
Nirav N Patel, Forrest R Stevens, Zhuojie Huang, Andrea E Gaughan, Iqbal Elyazar, Andrew J Tatem
Many different methods are used to disaggregate census data and predict population densities to construct finer scale, gridded population data sets. These methods often involve a range of high resolution geospatial covariate datasets on aspects such as urban areas, infrastructure, land cover and topography; such covariates, however, are not directly indicative of the presence of people. Here we tested the potential of geo-located tweets from the social media application, Twitter, as a covariate in the production of population maps...
April 2017: Transactions in GIS: TG
Mimi Gong, Shasha Yin, Xingke Gu, Yuanqian Xu, Nan Jiang, Ruiqin Zhang
Vehicle emission is becoming one of the most important pollution sources because of the increase in vehicle population and activity in China. A more reasonable and complete vehicle emission inventory in Zhengzhou for the year 2013 was developed in this study. This inventory is suitable for local emission factors and vehicle kilometers of travel. Estimates show that the total carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOX), particulate matter (PM2.5 and PM10) and sulfur dioxide (SO2) emissions were 291Gg, 35Gg, 106Gg, 6Gg, 7Gg, and 3Gg, respectively...
May 12, 2017: Science of the Total Environment
Jochen Winterer, Nikolaus Maier, Christian Wozny, Prateep Beed, Jörg Breustedt, Roberta Evangelista, Yangfan Peng, Tiziano D'Albis, Richard Kempter, Dietmar Schmitz
The distinctive firing pattern of grid cells in the medial entorhinal cortex (MEC) supports its role in the representation of space. It is widely believed that the hexagonal firing field of grid cells emerges from neural dynamics that depend on the local microcircuitry. However, local networks within the MEC are still not sufficiently characterized. Here, applying up to eight simultaneous whole-cell recordings in acute brain slices, we demonstrate the existence of unitary excitatory connections between principal neurons in the superficial layers of the MEC...
May 9, 2017: Cell Reports
Gerald Chikowore, Ahmadou H Dicko, Peter Chinwada, Moses Zimba, William Shereni, François Roger, Jérémy Bouyer, Laure Guerrini
BACKGROUND: Tsetse (Glossina sensu stricto) are cyclical vectors of human and animal trypanosomoses, that are presently targeted by the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) coordinated by the African Union. In order to achieve effective control of tsetse, there is need to produce elaborate plans to guide intervention programmes. A model intended to aid in the planning of intervention programmes and assist a fuller understanding of tsetse distribution was applied, in a pilot study in the Masoka area, Mid-Zambezi valley in Zimbabwe, and targeting two savannah species, Glossina morsitans morsitans and Glossina pallidipes...
May 2017: PLoS Neglected Tropical Diseases
Veronika Röthlisberger, Andreas P Zischg, Margreth Keiler
A sound understanding of flood risk drivers (hazard, exposure and vulnerability) is essential for the effective and efficient implementation of risk-reduction strategies. In this paper, we focus on 'exposure' and study the influence of different methods and parameters of flood exposure analyses in Switzerland. We consider two types of exposure indicators and two different spatial aggregation schemes: the density of exposed assets (exposed numbers per km(2)) and the ratios of exposed assets (share of exposed assets compared to total amount of assets in a specific region) per municipality and per grid cells of similar size as the municipalities...
April 25, 2017: Science of the Total Environment
Rosa A Scherson, Andrew H Thornhill, Rafael Urbina-Casanova, William A Freyman, Patricio A Pliscoff, Brent D Mishler
Current geographic patterns of biodiversity are a consequence of the evolutionary history of the lineages that comprise them. This study was aimed at exploring how evolutionary features of the vascular flora of Chile are distributed across the landscape. Using a phylogeny at the genus level for 87% of the Chilean vascular flora, and a geographic database of sample localities, we calculated phylogenetic diversity (PD), phylogenetic endemism (PE), relative PD (RPD), and relative PE (RPE). Categorical Analyses of Neo- and Paleo-Endemism (CANAPE) were also performed, using a spatial randomization to assess statistical significance...
April 24, 2017: Molecular Phylogenetics and Evolution
Mona M Garvert, Raymond J Dolan, Timothy Ej Behrens
The hippocampal-entorhinal system encodes a map of space that guides spatial navigation. Goal-directed behaviour outside of spatial navigation similarly requires a representation of abstract forms of relational knowledge. This information relies on the same neural system, but it is not known whether the organisational principles governing continuous maps may extend to the implicit encoding of discrete, non-spatial graphs. Here, we show that the human hippocampal-entorhinal system can represent relationships between objects using a metric that depends on associative strength...
April 27, 2017: ELife
Satoshi Eifuku
First, Brodmann areas 27, 28, 36 and 37, were anatomically defined in the beginning of this review. These areas exist in the parahippocampal or fusiform gyrus of the ventral temporal lobe in humans. Subsequently, the current understanding of their functions was summarized on the basis of recent findings mainly through human functional neuroimaging studies and animal studies. Rodent studies have shown the existence of neuronal activities for representing space, such as those involving head-direction cells or grid cells, in areas 27 (the parasubicular cortex) and 28 (the ventral entorhinal cortex)...
April 2017: Brain and Nerve, Shinkei Kenkyū No Shinpo
Jichao He, David W Wanik, Brian M Hartman, Emmanouil N Anagnostou, Marina Astitha, Maria E B Frediani
This article compares two nonparametric tree-based models, quantile regression forests (QRF) and Bayesian additive regression trees (BART), for predicting storm outages on an electric distribution network in Connecticut, USA. We evaluated point estimates and prediction intervals of outage predictions for both models using high-resolution weather, infrastructure, and land use data for 89 storm events (including hurricanes, blizzards, and thunderstorms). We found that spatially BART predicted more accurate point estimates than QRF...
March 2017: Risk Analysis: An Official Publication of the Society for Risk Analysis
Zoltan Nadasdy, T Peter Nguyen, Ágoston Török, Jason Y Shen, Deborah E Briggs, Pradeep N Modur, Robert J Buchanan
The spatially periodic activity of grid cells in the entorhinal cortex (EC) of the rodent, primate, and human provides a coordinate system that, together with the hippocampus, informs an individual of its location relative to the environment and encodes the memory of that location. Among the most defining features of grid-cell activity are the 60° rotational symmetry of grids and preservation of grid scale across environments. Grid cells, however, do display a limited degree of adaptation to environments. It remains unclear if this level of environment invariance generalizes to human grid-cell analogs, where the relative contribution of visual input to the multimodal sensory input of the EC is significantly larger than in rodents...
April 25, 2017: Proceedings of the National Academy of Sciences of the United States of America
Kiah Hardcastle, Niru Maheswaranathan, Surya Ganguli, Lisa M Giocomo
Medial entorhinal grid cells display strikingly symmetric spatial firing patterns. The clarity of these patterns motivated the use of specific activity pattern shapes to classify entorhinal cell types. While this approach successfully revealed cells that encode boundaries, head direction, and running speed, it left a majority of cells unclassified, and its pre-defined nature may have missed unconventional, yet important coding properties. Here, we apply an unbiased statistical approach to search for cells that encode navigationally relevant variables...
April 19, 2017: Neuron
Jidong Wu, Ying Li, Ning Li, Peijun Shi
The extent of economic losses due to a natural hazard and disaster depends largely on the spatial distribution of asset values in relation to the hazard intensity distribution within the affected area. Given that statistical data on asset value are collected by administrative units in China, generating spatially explicit asset exposure maps remains a key challenge for rapid postdisaster economic loss assessment. The goal of this study is to introduce a top-down (or downscaling) approach to disaggregate administrative-unit level asset value to grid-cell level...
April 5, 2017: Risk Analysis: An Official Publication of the Society for Risk Analysis
E N Bui, A H Thornhill, C E González-Orozco, N Knerr, J T Miller
Eucalypts cover most of Australia. Here, we investigate the relative contribution of climate and geochemistry to the distribution and diversity of eucalypts. Using geostatistics, we estimate major element concentrations, pH, and electrical conductivity at sites where eucalypts have been recorded. We compare the median predicted geochemistry and reported substrate for individual species that appear associated with extreme conditions; this provides a partial evaluation of the predictions. We generate a site-by-species matrix by aggregating observations to the centroids of 100-km-wide grid cells, calculate diversity indices, and use numerical ecology methods (ordination, variation partitioning) to investigate the ecology of eucalypts and their response to climatic and geochemical gradients...
May 2017: Geobiology
Tarin Paz-Kagan, Tamir Caras, Ittai Herrmann, Moshe Shachak, Arnon Karnieli
Land-use changes are one of the most important factors causing environmental transformations and species diversity alterations. The aim of the current study was to develop a geoinformatics-based framework to quantify alpha and beta diversity indices in two sites in Israel with different land-uses, i.e., an agricultural system of fruit orchards, an afforestation system of planted groves, and an unmanaged system of groves. The framework comprises four scaling steps: (1) classification of a tree species distribution (SD) map using imaging spectroscopy (IS) at a pixel size of 1 m; (2) estimation of local species richness by calculating the alpha diversity index for 30-m grid cells; (3) calculation of beta diversity for different land-use categories and sub-categories at different sizes; and (4) calculation of the beta diversity difference between the two sites...
March 28, 2017: Ecological Applications: a Publication of the Ecological Society of America
Danica J Stark, Ian P Vaughan, Diana A Ramirez Saldivar, Senthilvel K S S Nathan, Benoit Goossens
The development of GPS tags for tracking wildlife has revolutionised the study of home ranges, habitat use and behaviour. Concomitantly, there have been rapid developments in methods for estimating habitat use from GPS data. In combination, these changes can cause challenges in choosing the best methods for estimating home ranges. In primatology, this issue has received little attention, as there have been few GPS collar-based studies to date. However, as advancing technology is making collaring studies more feasible, there is a need for the analysis to advance alongside the technology...
2017: PloS One
Dmitriy Aronov, Rhino Nevers, David W Tank
During spatial navigation, neural activity in the hippocampus and the medial entorhinal cortex (MEC) is correlated to navigational variables such as location, head direction, speed, and proximity to boundaries. These activity patterns are thought to provide a map-like representation of physical space. However, the hippocampal-entorhinal circuit is involved not only in spatial navigation, but also in a variety of memory-guided behaviours. The relationship between this general function and the specialized spatial activity patterns is unclear...
March 29, 2017: Nature
Oliver Angélil, Sarah Perkins-Kirkpatrick, Lisa V Alexander, Dáithí Stone, Markus G Donat, Michael Wehner, Hideo Shiogama, Andrew Ciavarella, Nikolaos Christidis
A growing field of research aims to characterise the contribution of anthropogenic emissions to the likelihood of extreme weather and climate events. These analyses can be sensitive to the shapes of the tails of simulated distributions. If tails are found to be unrealistically short or long, the anthropogenic signal emerges more or less clearly, respectively, from the noise of possible weather. Here we compare the chance of daily land-surface precipitation and near-surface temperature extremes generated by three Atmospheric Global Climate Models typically used for event attribution, with distributions from six reanalysis products...
September 2016: Weather and Climate Extremes
Geoffrey W Diehl, Olivia J Hon, Stefan Leutgeb, Jill K Leutgeb
The medial entorhinal cortex (mEC) has been identified as a hub for spatial information processing by the discovery of grid, border, and head-direction cells. Here we find that in addition to these well-characterized classes, nearly all of the remaining two-thirds of mEC cells can be categorized as spatially selective. We refer to these cells as nongrid spatial cells and confirmed that their spatial firing patterns were unrelated to running speed and highly reproducible within the same environment. However, in response to manipulations of environmental features, such as box shape or box color, nongrid spatial cells completely reorganized their spatial firing patterns...
April 5, 2017: Neuron
Yangfan Peng, Federico J Barreda Tomás, Constantin Klisch, Imre Vida, Jörg R P Geiger
The presubiculum is part of the parahippocampal spatial navigation system and contains head direction and grid cells upstream of the medial entorhinal cortex. This position within the parahippocampal cortex renders the presubiculum uniquely suited for analyzing the circuit requirements underlying the emergence of spatially tuned neuronal activity. To identify the local circuit properties, we analyzed the topology of synaptic connections between pyramidal cells and interneurons in all layers of the presubiculum by testing 4250 potential synaptic connections using multiple whole-cell recordings of up to 8 cells simultaneously...
April 1, 2017: Cerebral Cortex
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