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https://www.readbyqxmd.com/read/28769779/size-matters-how-scaling-affects-the-interaction-between-grid-and-border-cells
#1
Diogo Santos-Pata, Riccardo Zucca, Sock C Low, Paul F M J Verschure
Many hippocampal cell types are characterized by a progressive increase in scale along the dorsal-to-ventral axis, such as in the cases of head-direction, grid and place cells. Also located in the medial entorhinal cortex (MEC), border cells would be expected to benefit from such scale modulations. However, this phenomenon has not been experimentally observed. Grid cells in the MEC of mammals integrate velocity related signals to map the environment with characteristic hexagonal tessellation patterns. Due to the noisy nature of these input signals, path integration processes tend to accumulate errors as animals explore the environment, leading to a loss of grid-like activity...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28768062/self-organization-of-modular-activity-of-grid-cells
#2
Eugenio Urdapilleta, Bailu Si, Alessandro Treves
A unique topographical representation of space is found in the concerted activity of grid cells in the rodent medial entorhinal cortex. Many among the principal cells in this region exhibit a hexagonal firing pattern, in which each cell expresses its own set of place fields (spatial phases) at the vertices of a triangular grid, the spacing and orientation of which are typically shared with neighboring cells. Grid spacing, in particular, has been found to increase along the dorso-ventral axis of the entorhinal cortex but in discrete steps, i...
August 2, 2017: Hippocampus
https://www.readbyqxmd.com/read/28767717/disentangling-the-influence-of-environmental-and-anthropogenic-factors-on-the-distribution-of-endemic-vascular-plants-in-sardinia
#3
Mauro Fois, Giuseppe Fenu, Eva Maria Cañadas, Gianluigi Bacchetta
Due to the impelling urgency of plant conservation and the increasing availability of high resolution spatially interpolated (e.g. climate variables) and categorical data (e.g. land cover and vegetation type), many recent studies have examined relationships among plant species distributions and a diversified set of explanatory factors; nevertheless, global and regional patterns of endemic plant richness remain in many cases unexplained. One such pattern is the 294 endemic vascular plant taxa recorded on a 1 km resolution grid on the environmentally heterogeneous island of Sardinia...
2017: PloS One
https://www.readbyqxmd.com/read/28767687/a-novel-on-line-spatial-temporal-k-anonymity-method-for-location-privacy-protection-from-sequence-rules-based-inference-attacks
#4
Haitao Zhang, Chenxue Wu, Zewei Chen, Zhao Liu, Yunhong Zhu
Analyzing large-scale spatial-temporal k-anonymity datasets recorded in location-based service (LBS) application servers can benefit some LBS applications. However, such analyses can allow adversaries to make inference attacks that cannot be handled by spatial-temporal k-anonymity methods or other methods for protecting sensitive knowledge. In response to this challenge, first we defined a destination location prediction attack model based on privacy-sensitive sequence rules mined from large scale anonymity datasets...
2017: PloS One
https://www.readbyqxmd.com/read/28763654/evaluating-the-risk-of-phosphorus-loss-with-a-distributed-watershed-model-featuring-zero-order-mobilization-and-first-order-delivery
#5
Sisi Li, Liang Zhang, Hongbin Liu, Hugo A Loáiciga, Limei Zhai, Yanhua Zhuang, Qiuliang Lei, Wanli Hu, Wenchao Li, Qi Feng, Yun Du
Many semi-distributed models that simulate pollutants' losses from watersheds do not handle well detailed spatially distributed and temporal data with which to identify accurate and cost-effective strategies for controlling pollutants issuing from non-point sources. Such models commonly overlook the flow pathways of pollutants across the landscape. This work aims at closing such knowledge gap by developing a Spatially and Temporally Distributed Empirical model for Phosphorus Management (STEM-P) that simulates the daily phosphorus loss from source areas to receiving waters on a spatially-distributed grid-cell basis...
July 27, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28756950/grid-cells-encode-local-positional-information
#6
Revekka Ismakov, Omri Barak, Kate Jeffery, Dori Derdikman
The brain has an extraordinary ability to create an internal spatial map of the external world [1]. This map-like representation of environmental surroundings is encoded through specific types of neurons, located within the hippocampus and entorhinal cortex, which exhibit spatially tuned firing patterns [2, 3]. In addition to encoding space, these neurons are believed to be related to contextual information and memory [4-7]. One class of such cells is the grid cells, which are located within the entorhinal cortex, presubiculum, and parasubiculum [3, 8]...
August 7, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28750005/from-grid-cells-to-place-cells-with-realistic-field-sizes
#7
Torsten Neher, Amir Hossein Azizi, Sen Cheng
While grid cells in the medial entorhinal cortex (MEC) of rodents have multiple, regularly arranged firing fields, place cells in the cornu ammonis (CA) regions of the hippocampus mostly have single spatial firing fields. Since there are extensive projections from MEC to the CA regions, many models have suggested that a feedforward network can transform grid cell firing into robust place cell firing. However, these models generate place fields that are consistently too small compared to those recorded in experiments...
2017: PloS One
https://www.readbyqxmd.com/read/28748383/is-ambient-heat-exposure-levels-associated-with-miscarriage-or-stillbirths-in-hot-regions-a-cross-sectional-study-using-survey-data-from-the-ghana-maternal-health-survey-2007
#8
Benedict Asamoah, Tord Kjellstrom, Per-Olof Östergren
It is well established that high ambient heat could cause congenital abnormalities resulting in miscarriage or stillbirth among certain species of mammals. However, this has not been systematically studied in real field settings among humans, despite the potential value of such knowledge for estimating the impact of global warming on the human species. This study sought to test the hypothesis that maternal heat exposure during pregnancy in hot regions is associated with increased prevalence of spontaneous abortions or stillbirths and to develop an analytical strategy to use existing data from maternal health surveys and existing data on historical heat levels at a geographic grid cell level...
July 26, 2017: International Journal of Biometeorology
https://www.readbyqxmd.com/read/28731409/assessment-of-the-probability-of-autochthonous-transmission-of-chikungunya-virus-in-canada-under-recent-and-projected-climate-change
#9
Victoria Ng, Aamir Fazil, Philippe Gachon, Guillaume Deuymes, Milka Radojević, Mariola Mascarenhas, Sophiya Garasia, Michael A Johansson, Nicholas H Ogden
BACKGROUND: Chikungunya virus (CHIKV) is a reemerging pathogen transmitted by Aedes aegypti and Aedes albopictus mosquitoes. The ongoing Caribbean outbreak is of concern due to the potential for infected travelers to spread the virus to countries where vectors are present and the population is susceptible. Although there has been no autochthonous transmission of CHIKV in Canada, there is concern that both Ae. albopictus and CHIKV will become established, particularly under projected climate change...
June 5, 2017: Environmental Health Perspectives
https://www.readbyqxmd.com/read/28724433/gridsample-an-r-package-to-generate-household-survey-primary-sampling-units-psus-from-gridded-population-data
#10
Dana R Thomson, Forrest R Stevens, Nick W Ruktanonchai, Andrew J Tatem, Marcia C Castro
BACKGROUND: Household survey data are collected by governments, international organizations, and companies to prioritize policies and allocate billions of dollars. Surveys are typically selected from recent census data; however, census data are often outdated or inaccurate. This paper describes how gridded population data might instead be used as a sample frame, and introduces the R GridSample algorithm for selecting primary sampling units (PSU) for complex household surveys with gridded population data...
July 19, 2017: International Journal of Health Geographics
https://www.readbyqxmd.com/read/28708881/large-anthropogenic-impacts-on-a-charismatic-small-carnivore-insights-from-distribution-surveys-of-red-panda-ailurus-fulgens-in-nepal
#11
Saroj Panthi, Gopal Khanal, Krishna Prasad Acharya, Achyut Aryal, Arjun Srivathsa
Protected areas are key to preserving biodiversity and maintaining ecosystem services. However, their ability to ensure long-term survival of threatened andendangered species varies across countries, regions and landscapes. Distribution surveys can beparticularly important for assessing the value of protected areas, and gauging their efficacy incatering to species-specific requirements. We assessed the conservation value of one such reserve for a charismatic yet globally endangered species, the red panda Ailurus fulgens,in the light of on-going land-use transformation in Nepal...
2017: PloS One
https://www.readbyqxmd.com/read/28703324/scaling-range-sizes-to-threats-for-robust-predictions-of-risks-to-biodiversity
#12
David A Keith, H Resit Akçakaya, Nicholas J Murray
Assessments of risk to biodiversity often rely on spatial distributions of species and ecosystems. Range size metrics used extensively in these assessments, such as Area of Occupancy (AOO), are sensitive to measurement scale, prompting proposals to measure them at finer scales, or a variery of different scales based on the shape of the distribution or ecological characteristics of the biota. Despite its dominant role in Red List assessments for decades, appropriate spatial scales of AOO for predicting risks of species extinction or ecosystem collapse remain untested and contentious...
July 13, 2017: Conservation Biology: the Journal of the Society for Conservation Biology
https://www.readbyqxmd.com/read/28701481/place-and-grid-cells-in-a-loop-implications-for-memory-function-and-spatial-coding
#13
César Rennó-Costa, Adriano B L Tort
Place cells in the hippocampus and grid cells in the medial entorhinal cortex have different codes for space. However, how one code relates to the other is ill understood. Based on the anatomy of the entorhinal-hippocampal circuitry, we constructed a model of place and grid cells organized in a loop to investigate their mutual influence in the establishment of their codes for space. Using computer simulations, we first replicated experiments in rats that measured place and grid cell activity in different environments, and then assessed which features of the model account for different phenomena observed in neurophysiological data, such as pattern completion and pattern separation, global and rate remapping of place cells and realignment of grid cells...
July 12, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28683931/filling-the-gap-using-fishers-knowledge-to-map-the-extent-and-intensity-of-fishing-activity
#14
Claire L Szostek, Lee G Murray, Ewen Bell, Michel J Kaiser
Knowledge of the extent and intensity of fishing activities is critical to inform management in relation to fishing impacts on marine conservation features. Such information can also provide insight into the potential socio-economic impacts of closures (or other restrictions) of fishing grounds that could occur through the future designation of Marine Conservation Zones (MCZs). We assessed the accuracy and validity of fishing effort data (spatial extent and relative effort) obtained from Fishers' Local Knowledge (LK) data compared to that derived from Vessel Monitoring System (VMS) data for a high-value shellfish fishery, the king scallop (Pecten maximus L...
June 20, 2017: Marine Environmental Research
https://www.readbyqxmd.com/read/28678438/examining-the-relationship-between-local-extinction-risk-and-position-in-range
#15
Elizabeth H Boakes, Nicholas J B Isaac, Richard A Fuller, Georgina M Mace, Philip J K McGowan
Over half of globally threatened animal species have experienced rapid geographic range loss. Identifying the parts of species' distributions most vulnerable to extinction would benefit conservation planning. However, previous studies give little consensus on whether ranges decline to the core or edge. Here we build on previous work by using empirical data to examine the position of recent local extinctions within species' geographic ranges, addressing range position as a continuum and exploring the influence of environmental factors...
July 5, 2017: Conservation Biology: the Journal of the Society for Conservation Biology
https://www.readbyqxmd.com/read/28675670/predicting-the-abundance-of-forest-types-across-the-eastern-u-s-through-inverse-modelling-of-tree-demography
#16
Mark C Vanderwel, Danaë M A Rozendaal, Margaret E K Evans
Global environmental change is expected to induce widespread changes in the geographic distribution and biomass of forest communities. Impacts have been projected from both empirical (statistical) and mechanistic (physiology-based) modelling approaches, but there remains an important gap in accurately predicting abundance across species' ranges from spatial variation in individual-level demographic processes. We address this issue by using a cohort-based forest dynamics model (CAIN) to predict spatial variation in the abundance of six plant functional types (PFTs) across the eastern U...
July 4, 2017: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/28667472/erratum-to-combined-effect-of-pulse-density-and-grid-cell-size-on-predicting-and-mapping-aboveground-carbon-in-fast-growing-eucalyptus-forest-plantation-using-airborne-lidar-data
#17
Carlos Alberto Silva, Andrew Thomas Hudak, Carine Klauberg, Lee Alexandre Vierling, Carlos Gonzalez-Benecke, Samuel de Padua Chaves Carvalho, Luiz Carlos Estraviz Rodriguez, Adrián Cardil
No abstract text is available yet for this article.
December 2017: Carbon Balance and Management
https://www.readbyqxmd.com/read/28640608/numerical-difficulties-computing-electrostatic-potentials-near-interfaces-with-the-poisson-boltzmann-equation
#18
Robert C Harris, Alexander H Boschitsch, Marcia O Fenley
Many researchers compute surface maps of the electrostatic potential (φ) with the Poisson-Boltzmann (PB) equation to relate the structural information obtained from X-ray and NMR experiments to biomolecular functions. Here we demonstrate that the usual method of obtaining these surface maps of φ, by interpolating from neighboring grid points on the solution grid generated by a PB solver, generates large errors because of the large discontinuity in the dielectric constant (and thus in the normal derivative of φ) at the surface...
July 17, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28628647/an-efficient-coding-theory-for-a-dynamic-trajectory-predicts-non-uniform-allocation-of-entorhinal-grid-cells-to-modules
#19
Noga Mosheiff, Haggai Agmon, Avraham Moriel, Yoram Burak
Grid cells in the entorhinal cortex encode the position of an animal in its environment with spatially periodic tuning curves with different periodicities. Recent experiments established that these cells are functionally organized in discrete modules with uniform grid spacing. Here we develop a theory for efficient coding of position, which takes into account the temporal statistics of the animal's motion. The theory predicts a sharp decrease of module population sizes with grid spacing, in agreement with the trend seen in the experimental data...
June 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28628104/active-dendritic-integration-as-a-mechanism-for-robust-and-precise-grid-cell-firing
#20
Christoph Schmidt-Hieber, Gabija Toleikyte, Laurence Aitchison, Arnd Roth, Beverley A Clark, Tiago Branco, Michael Häusser
Understanding how active dendrites are exploited for behaviorally relevant computations is a fundamental challenge in neuroscience. Grid cells in medial entorhinal cortex are an attractive model system for addressing this question, as the computation they perform is clear: they convert synaptic inputs into spatially modulated, periodic firing. Whether active dendrites contribute to the generation of the dual temporal and rate codes characteristic of grid cell output is unknown. We show that dendrites of medial entorhinal cortex neurons are highly excitable and exhibit a supralinear input-output function in vitro, while in vivo recordings reveal membrane potential signatures consistent with recruitment of active dendritic conductances...
August 2017: Nature Neuroscience
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