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Grid Cell

Nikolaus Kriegeskorte, Katherine R Storrs
"Grid cells" encode an animal's location and direction of movement in 2D physical environments via regularly repeating receptive fields. Constantinescu et al. (2016) report the first evidence of grid cells for 2D conceptual spaces. The work has exciting implications for mental representation and shows how detailed neural-coding hypotheses can be tested with bulk population-activity measures.
October 19, 2016: Neuron
Yongseok Yoo, Woori Kim
Neural systems are inherently noisy. One well-studied example of a noise reduction mechanism in the brain is the population code, where representing a variable with multiple neurons allows the encoded variable to be recovered with fewer errors. Studies have assumed ideal observer models for decoding population codes, and the manner in which information in the neural population can be retrieved remains elusive. This letter addresses a mechanism by which realistic neural circuits can recover encoded variables...
October 20, 2016: Neural Computation
William Severa, Ojas Parekh, Conrad D James, James B Aimone
The dentate gyrus forms a critical link between the entorhinal cortex and CA3 by providing a sparse version of the signal. Concurrent with this increase in sparsity, a widely accepted theory suggests the dentate gyrus performs pattern separation-similar inputs yield decorrelated outputs. Although an active region of study and theory, few logically rigorous arguments detail the dentate gyrus's (DG) coding. We suggest a theoretically tractable, combinatorial model for this action. The model provides formal methods for a highly redundant, arbitrarily sparse, and decorrelated output signal...
October 20, 2016: Neural Computation
Sang-Yoon Lee, Eun Kyoung Lee, Ki Ho Park, Dong Myung Kim, Jin Wook Jeoung
PURPOSE: To report an asymmetry analysis of macular inner retinal layers using swept-source optical coherence tomography (OCT) and to evaluate the utility for glaucoma diagnosis. DESIGN: Observational, cross-sectional study. PARTICIPANTS: Seventy normal healthy subjects and 62 glaucoma patients. METHODS: Three-dimensional scans were acquired from 70 normal subjects and 62 open angle glaucoma patients by swept-source OCT...
2016: PloS One
Radu Danescu, Razvan Itu, Andra Petrovai
The driving environment is complex and dynamic, and the attention of the driver is continuously challenged, therefore computer based assistance achieved by processing image and sensor data may increase traffic safety. While active sensors and stereovision have the advantage of obtaining 3D data directly, monocular vision is easy to set up, and can benefit from the increasing computational power of smart mobile devices, and from the fact that almost all of them come with an embedded camera. Several driving assistance application are available for mobile devices, but they are mostly targeted for simple scenarios and a limited range of obstacle shapes and poses...
October 17, 2016: Sensors
Pablo Arturo Fernández Garrillo, Lukasz Borowik, Florent Caffy, Renaud Demadrille, Benjamin Grevin
Investigating the photo-carrier dynamics in nanostructured and heterogeneous energy materials is of crucial importance from both fundamental and technological points of view. Here, we demonstrate how non-contact atomic force microscopy combined with Kelvin Probe Force Microscopy under frequency modulated illumination can be used to simultaneously image the surface photo-potential dynamics at different timescales with a sub-10 nm lateral resolution. The basic principle of the method consists in the acquisition of spectroscopic curves of the surface potential as a function of the illumination frequency modulation on a two dimensional grid...
October 20, 2016: ACS Applied Materials & Interfaces
J Augustin, J Austermann, S Erasmi
Background: One of the overall objectives of the legislator is to ensure an overall "homogeneous", and easily accessible medical care for the population. The physician-patient ratio can be used to describe the regional health care situation. But this method does not provide information concerning the availability of, for instance, the nearest doctor. Therefore, further parameters such as accessibility must be taken into consideration. For this purpose, network analyses are an appropriate method. The objective of this study is to present methodological tools to evaluate the healthcare situation in the metropolitan region of Hamburg, primarily focusing on accessibility using dermatologists as an example...
October 18, 2016: Das Gesundheitswesen
R Behnke, S Vavrus, A Allstadt, T Albright, W E Thogmartin, V C Radeloff
Weather and climate affect many ecological processes, making spatially continuous yet fine-resolution weather data desirable for ecological research and predictions. Numerous downscaled weather data sets exist, but little attempt has been made to evaluate them systematically. Here we address this shortcoming by focusing on four major questions: (1) How accurate are downscaled, gridded climate data sets in terms of temperature and precipitation estimates? (2) Are there significant regional differences in accuracy among data sets? (3) How accurate are their mean values compared with extremes? (4) Does their accuracy depend on spatial resolution? We compared eight widely used downscaled data sets that provide gridded daily weather data for recent decades across the United States...
July 2016: Ecological Applications: a Publication of the Ecological Society of America
Tobias Janoschka, Norbert Martin, Martin D Hager, Ulrich S Schubert
Redox-flow batteries (RFB) can easily store large amounts of electric energy and thereby mitigate the fluctuating output of renewable power plants. They are widely discussed as energy-storage solutions for wind and solar farms to improve the stability of the electrical grid. Most common RFB concepts are based on strongly acidic metal-salt solutions or poorly performing organics. Herein we present a battery which employs the highly soluble N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) and the viologen derivative N,N'-dimethyl-4,4-bipyridinium dichloride (MV) in a simple and safe aqueous solution as redox-active materials...
October 18, 2016: Angewandte Chemie
Christopher J Benjamin, Kyle J Wright, Scott C Bolton, Seok-Hee Hyun, Kyle Krynski, Mahima Grover, Guimei Yu, Fei Guo, Tamara L Kinzer-Ursem, Wen Jiang, David H Thompson
We report the fabrication of transmission electron microscopy (TEM) grids bearing graphene oxide (GO) sheets that have been modified with N(α), N(α)-dicarboxymethyllysine (NTA) and deactivating agents to block non-selective binding between GO-NTA sheets and non-target proteins. The resulting GO-NTA-coated grids with these improved antifouling properties were then used to isolate His6-T7 bacteriophage and His6-GroEL directly from cell lysates. To demonstrate the utility and simplified workflow enabled by these grids, we performed cryo-electron microscopy (cryo-EM) of His6-GroEL obtained from clarified E...
October 17, 2016: Scientific Reports
Yuting Zhou, Xiangming Xiao, Yuanwei Qin, Jinwei Dong, Geli Zhang, Weili Kou, Cui Jin, Jie Wang, Xiangping Li
Accurate and up-to-date information on the spatial distribution of paddy rice fields is necessary for the studies of trace gas emissions, water source management, and food security. The phenology-based paddy rice mapping algorithm, which identifies the unique flooding stage of paddy rice, has been widely used. However, identification and mapping of paddy rice in rice-wetland coexistent areas is still a challenging task. In this study, we found that the flooding/transplanting periods of paddy rice and natural wetlands were different...
April 2016: International Journal of Applied Earth Observation and Geoinformation: ITC Journal
Holger Dannenberg, James R Hinman, Michael E Hasselmo
Behavioral data suggest that cholinergic modulation may play a role in certain aspects of spatial memory, and neurophysiological data demonstrate neurons that fire in response to spatial dimensions, including grid cells and place cells that respond on the basis of location and running speed. These neurons show firing responses that depend upon the visual configuration of the environment, due to coding in visually-responsive regions of the neocortex. This review focuses on the physiological effects of acetylcholine that may influence the sensory coding of spatial dimensions relevant to behavior...
September 24, 2016: Journal of Physiology, Paris
Rui Liu, Yun Chen, Jianping Wu, Lei Gao, Damian Barrett, Tingbao Xu, Xiaojuan Li, Linyi Li, Chang Huang, Jia Yu
Regional flood risk caused by intensive rainfall under extreme climate conditions has increasingly attracted global attention. Mapping and evaluation of flood hazard are vital parts in flood risk assessment. This study develops an integrated framework for estimating spatial likelihood of flood hazard by coupling weighted naïve Bayes (WNB), geographic information system, and remote sensing. The north part of Fitzroy River Basin in Queensland, Australia, was selected as a case study site. The environmental indices, including extreme rainfall, evapotranspiration, net-water index, soil water retention, elevation, slope, drainage proximity, and density, were generated from spatial data representing climate, soil, vegetation, hydrology, and topography...
September 24, 2016: Risk Analysis: An Official Publication of the Society for Risk Analysis
Argo Ronk, Francesco de Bello, Pavel Fibich, Meelis Pärtel
Large-scale biodiversity studies can be more informative if observed diversity in a study site is accompanied by dark diversity, the set of absent although ecologically suitable species. Dark diversity methodology is still being developed and a comparison of different approaches is needed. We used plant data at two different scales (European and seven large regions) and compared dark diversity estimates from two mathematical methods: species co-occurrence (SCO) and species distribution modeling (SDM). We used plant distribution data from the Atlas Florae Europaeae (50 × 50 km grid cells) and seven different European regions (10 × 10 km grid cells)...
September 2016: Ecology and Evolution
Georgios Gerogiokas, Michelle W Y Southey, Michael P Mazanetz, Alexander Heifetz, Michael Bodkin, Richard J Law, Richard H Henchman, J Michel
Molecular dynamics simulations have been analyzed with the Grid Cell Theory (GCT) method to spatially resolve the binding enthalpies and entropies of water molecules at the interface of 17 structurally diverse proteins. Correlations between computed energetics and structural descriptors have been sought to facilitate the development of simple models of protein hydration. Little correlation was found between GCT-computed binding enthalpies and continuum electrostatics calculations. A simple count of contacts with functional groups in charged amino acids correlates well with enhanced water stabilization, but the stability of water near hydrophobic and polar residues depends markedly on its coordination environment...
October 13, 2016: Journal of Physical Chemistry. B
Corinna S Bazelet, Aileen C Thompson, Piotr Naskrecki
The use of endemism and vascular plants only for biodiversity hotspot delineation has long been contested. Few studies have focused on the efficacy of global biodiversity hotspots for the conservation of insects, an important, abundant, and often ignored component of biodiversity. We aimed to test five alternative diversity measures for hotspot delineation and examine the efficacy of biodiversity hotspots for conserving a non-typical target organism, South African katydids. Using a 1° fishnet grid, we delineated katydid hotspots in two ways: (1) count-based: grid cells in the top 10% of total, endemic, threatened and/or sensitive species richness; vs...
2016: PloS One
Marie Hébert, Antoine Anfray, Arnaud Chevilley, Sara Martinez de Lizarrondo, Aurélien Quenault, Morgane Louessard, Benoit D Roussel, Pauline Obiang, Etienne Save, Cyrille Orset, Eric Maubert, Denis Vivien, Véronique Agin
In humans, spatial cognition and navigation impairments are a frequent situation during physiological and pathological aging, leading to a dramatic deterioration in the quality of life. Despite the discovery of neurons with location-specific activity in rodents, that is, place cells in the hippocampus and later on grid cells in the entorhinal cortex (EC), the molecular mechanisms underlying spatial cognition are still poorly known. Our present data bring together in an unusual combination 2 molecules of primary biological importance: a major neuronal excitatory receptor, N-methyl-D-aspartate receptor (NMDAR), and an extracellular protease, tissue plasminogen activator (tPA), in the control of spatial navigation...
September 9, 2016: Cerebral Cortex
Yuanqing Li, Chong Liu, Yi Cui, Spencer S Walse, Ryan Olver, David Zilberman, William A Mitch
Due to concerns surrounding its ozone depletion potential, there is a need for technologies to capture and destroy methyl bromide (CH3Br) emissions from postharvest fumigations applied to control agricultural pests. Previously, we described a system in which CH3Br fumes vented from fumigation chambers could be captured by granular activated carbon (GAC). The GAC was converted to a cathode by submergence in a high ionic strength solution and connection to the electrical grid, resulting in reductive debromination of the sorbed CH3Br...
October 18, 2016: Environmental Science & Technology
Yvonne Roger, Luisa Marilena Schäck, Anastasia Koroleva, Sandra Noack, Kestutis Kurselis, Christian Krettek, Boris Chichkov, Thomas Lenarz, Athanasia Warnecke, Andrea Hoffmann
The use of autologous cells for the coating of implant surfaces presents a promising tool to attenuate foreign body reaction and inflammation. However, insertion forces that occur especially during implantation of electrodes into the narrow cochlea may strip off cells from the surface. Thus, implant surfaces should be ideally structured in a way that protects the cell coating from mechanical removal during implantation. The structuring of implant surfaces may also direct cells towards desired functions to further enhance their performance and clinical suitability...
June 16, 2016: Colloids and Surfaces. B, Biointerfaces
Masaki Makihara, Takashi Watanabe, Eiji Usukura, Kozo Kaibuchi, Akihiro Narita, Nobuo Tanaka, Jiro Usukura
An improved unroofing method consisting of tearing off the cell membrane using an adhesive electron microscopy (EM) grid instead of vitreous ice sectioning (cryo-sectioning) has enabled us to panoramically view the membrane cytoskeleton in its native state with extremely high contrast. Grids pre-treated with Alcian blue were placed on cells, and a portion of the dorsal plasma membrane was transferred onto the grid, which was then floated in buffer solution. These membrane fragments contained sufficient cytoskeleton and were of suitable thickness for observation by cryo-EM...
September 1, 2016: Microscopy
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