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Grid cells

Dhanashree Ratra, Durgasri Jaishankar, Ramya Sachidanandam, Hatim Yusufali, Vineet Ratra
BACKGROUND: Stargardt disease, a juvenile retinal dystrophy, may show secondary changes in the choroid which may have importance while considering future treatments such as stem cell transplant. OBJECTIVE: To evaluate the choroidal and retinal morphology in patients with Stargardt disease and compare with age-matched normals. SETTING AND DESIGN: This was a case-control study at a tertiary level eye care institute. METHODS: Twenty-six patients (52 eyes) clinically diagnosed with Stargardt disease underwent detailed evaluation with swept-source optical coherence tomography...
May 2018: Oman Journal of Ophthalmology
Susana R Cerqueira, Yee-Shuan Lee, Robert C Cornelison, Michaela W Mertz, Rebecca A Wachs, Christine E Schmidt, Mary Bartlett Bunge
Schwann cell (SC) transplantation has been comprehensively studied as a strategy for spinal cord injury (SCI) repair. SCs are neuroprotective and promote axon regeneration and myelination. Nonetheless, substantial SC death occurs post-implantation, which limits therapeutic efficacy. The use of extracellular matrix (ECM)-derived matrices, such as Matrigel, supports transplanted SC survival and axon growth, resulting in improved motor function. Because appropriate matrices are needed for clinical translation, we test here the use of an acellular injectable peripheral nerve (iPN) matrix...
May 28, 2018: Biomaterials
Omar Zakary, Mostafa Rachik, Ilias Elmouki
First, we devise in this paper, a multi-regions discrete-time model which describes the spatial-temporal spread of an epidemic which starts from one region and enters to regions which are connected with their neighbors by any kind of anthropological movement. We suppose homogeneous Susceptible-Infected-Removed (SIR) populations, and we consider in our simulations, a grid of colored cells, which represents the whole domain affected by the epidemic while each cell can represent a sub-domain or region. Second, in order to minimize the number of infected individuals in one region, we propose an optimal control approach based on a travel-blocking vicinity strategy which aims to control only one cell by restricting movements of infected people coming from all neighboring cells...
August 2017: Infectious Disease Modelling
Mikhail A Lebedev, Alexey Pimashkin, Alexei Ossadtchi
According to the currently prevailing theory, hippocampal formation constructs and maintains cognitive spatial maps. Most of the experimental evidence for this theory comes from the studies on navigation in laboratory rats and mice, typically male animals. While these animals exhibit a rich repertoire of behaviors associated with navigation, including locomotion, head movements, whisking, sniffing, raring and scent marking, the contribution of these behavioral patterns to the hippocampal spatially-selective activity has not been sufficiently studied...
2018: Frontiers in Behavioral Neuroscience
Nina Berggaard, Mohsen Seifi, Johannes J L van der Want, Jerome D Swinny
GABAergic parvalbumin-expressing (PV+) interneurons provide powerful inhibitory modulation of grid cells in layer II of the medial entorhinal cortex (MEC LII). However, the molecular machinery through which PV+ cells regulate grid cell activity is poorly defined. PV+ interneurons impart inhibitory modulation primarily via GABA-A receptors (GABAA Rs). GABAA Rs are pentameric ion channels assembled from a repertoire of 19 subunits. Multiple subunit combinations result in a variety of receptor subtypes mediating functionally diverse postsynaptic inhibitory currents...
2018: Frontiers in Neuroanatomy
Zhaoling Li, Hasi Bagan, Yoshiki Yamagata
Land use has changed dramatically in the Inner Mongolia Autonomous Region because of rapid economic growth and human disturbances. However, little information is available about the medium- and long-term land use changes in this region. The effects of ecological recovery policies have also been evaluated rarely. In this study, we employed the self-organizing map neural network method to identify the land cover changes in Inner Mongolia between 2000 and 2014. MOD13Q1, Landsat, and DMSP/OLS night-time light data were used as the data resources...
September 15, 2018: Science of the Total Environment
Amir Shamloo, Saba Ahmad, Maede Momeni
Being the second cause of mortality across the globe, there is now a persistent effort to establish new cancer medication and therapies. Any accomplishment in treating cancers entails the existence of accurate identification systems empowering the early diagnosis. Recent studies indicate CTCs’ potential in cancer prognosis as well as therapy monitoring. The chief shortcoming with CTCs is that they are exceedingly rare cells in their clinically relevant concentration. Here, we simulated a microfluidic construct devised for immunomagnetic separation of the particles of interest from the background cells...
June 18, 2018: Biosensors
Guifen Chen, John Andrew King, Yi Lu, Francesca Cacucci, Neil Burgess
We present a mouse virtual reality (VR) system which restrains head-movements to horizontal rotations, compatible with multi-photon imaging. This system allows expression of the spatial navigation and neuronal firing patterns characteristic of real open arenas (R). Comparing VR to R: place and grid, but not head-direction, cell firing had broader spatial tuning; place, but not grid, cell firing was more directional; theta frequency increased less with running speed; whereas increases in firing rates with running speed and place and grid cells' theta phase precession were similar...
June 18, 2018: ELife
Zhaoxin Dai, Jean-Michel Guldmann, Yunfeng Hu
Understanding the relationship between urban land structure and land surface temperatures (LST) is important for mitigating the urban heat island (UHI). This paper explores this relationship within central Beijing, an area located within the 2nd Ring Road. The urban variables include the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Build-up Index (NDBI), the area of building footprints, the area of main roads, the area of water bodies and a gravity index for parks that account for both park size and distance...
June 1, 2018: Science of the Total Environment
Sean Robinson, Michael J Courtney
Motivation: The collective and coordinated synaptic activity of large neuronal populations is relevant to neuronal development as well as a range of neurological diseases. Quantification of synaptically-mediated neuronal signalling permits further downstream analysis as well as potential application in target validation and in vitro screening assays. Our aim is to develop a phenotypic quantification for neuronal activity imaging data of large populations of neurons, in particular relating to the spatial component of the activity...
April 20, 2018: Bioinformatics
Yuanyuan Ran, Zongjian Liu, Shuo Huang, Jiamei Shen, Fengwu Li, Wenxiu Zhang, Chen Chen, Xiaokun Geng, Zhili Ji, Huishan Du, Xiaoming Hu
Splenectomy before or immediately after stroke provides early brain protection. This study aims to explore the effect of splenectomy on long-term neurological recovery after stroke, which is currently lacking in the field. Adult male rats were randomized into splenectomy or sham groups and then subjected to 90 min of middle cerebral artery occlusion (MCAO). Spleen was removed right upon reperfusion or 3d after MCAO. Infarct volume, neurological functions, and peripheral immune cell populations were assessed up to 28d after stroke...
June 2018: Aging and Disease
Leah E Trigg, Feng Chen, Georgy I Shapiro, Simon N Ingram, Clare B Embling
Underwater noise pollution from shipping is a significant ecological concern. Acoustic propagation models are essential to predict noise levels and inform management activities to safeguard ecosystems. However, these models can be computationally expensive to execute. To increase computational efficiency, ships are spatially partitioned using grids but the cell size is often arbitrary. This work presents an adaptive grid where cell size varies with distance from the receiver to increase computational efficiency and accuracy...
June 2018: Marine Pollution Bulletin
Matthew R Hauwiller, Justin C Ondry, A Paul Alivisatos
Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in liquid environments. This manuscript describes the process for making graphene liquid cells through the example of graphene liquid cell transmission electron microscopy (TEM) experiments of gold nanocrystal etching. The protocol for making graphene liquid cells involves coating gold, holey-carbon TEM grids with chemical vapor deposition graphene and then using those graphene-coated grids to encapsulate liquid between two graphene surfaces...
May 17, 2018: Journal of Visualized Experiments: JoVE
Hanin Alamir, Mona Alomari, Abdulla Ahmed A Salwati, Mohamad Saka, Mohammed Bangash, Saleh Baeesa, Fahad Alghamdi, Angel Carracedo, Hans-Juergen Schulten, Adeel Chaudhary, Adel Abuzenadah, Deema Hussein
Background: Meningioma cancer stem cells (MCSCs) contribute to tumor aggressiveness and drug resistance. Successful therapies developed for inoperable, recurrent, or metastatic tumors must target these cells and restrict their contribution to tumor progression. Unfortunately, the identity of MCSCs remains elusive, and MSCSs' in situ spatial distribution, heterogeneity, and relationship with tumor grade, remain unclear. Methods: Seven tumors classified as grade II or grade III, including one case of metastatic grade III, and eight grade I meningioma tumors, were analyzed for combinations of ten stem cell (SC)-related markers using immunofluorescence of consecutive sections...
2018: Cancer Cell International
Fátima Jorge, Robert Poulin
Mapping global parasite diversity is crucial to identify geographical hotspots of emerging disease, and guide public health and conservation efforts. In principle, assuming a bottom-up coupling between the diversity of resources and consumers, the geographical distribution of parasite diversity should match that of host diversity. We test the expected spatial congruence between host and parasite diversity for helminth parasites of vertebrate hosts, across grid cells of a global map. Using high-resolution databases on host species distributions and newly compiled data on the geographical distribution of parasite species discovery, we found positive covariation between host species richness and the number of parasite species discovered, for all vertebrate groups, regardless of the analytical method used, spatial autocorrelation, and spatial resolution...
May 30, 2018: Proceedings. Biological Sciences
R N Gejl, P L Bjerg, H J Henriksen, M Z Hauschild, J Rasmussen, M Rygaard
Understanding groundwater abstraction effects is vital for holistic impact assessments in areas depending on groundwater resources. The objective of our study was to modify the state-of-the-art AWaRe (available water remaining), freshwater impact assessment specifically for use in LCAs in areas dependent on groundwater resources. The new method, called "AGWaRe" (available groundwater remaining), reflects groundwater availability, based on a fraction of available groundwater remaining locally relative to a reference...
May 25, 2018: Journal of Environmental Management
Xiugang Song, Hui Li, Ruixin Li, Qingxian Yuan, Yingjie Liu, Wei Cheng, Xizheng Zhang
Objective: To observe the effect of dynamic mechanical loading on the proliferation, differentiation, and specific gene expression of MC3T3-E1 cells that on three-dimensional (3D) biomimetic composite scaffolds prepared by low temperature 3D printing technology combined with freeze-drying. Methods: The silk fibroin, collagen type Ⅰ, and nano-hydroxyapatite (HA) were mixed at a mass ratio of 3∶9∶2 and were used to prepare the 3D biomimetic composite scaffolds via low temperature 3D printing technology combined with freeze-drying...
April 1, 2018: Chinese Journal of Reparative and Reconstructive Surgery
Ce Wang, Jun Bi, Xu-Xiang Zhang, Qiang Fang, Yi Qi
Influent river carrying cumulative watershed load plays a significant role in promoting nuisance algal bloom in river-fed lake. It is most relevant to discern in-stream water quality exceedance and evaluate the spatial relationship between risk location and potential pollution sources. However, no comprehensive studies of source tracking in watershed based on management grid have been conducted for refined water quality management, particularly for plain terrain with complex river network. In this study, field investigations were implemented during 2014 in Taige Canal watershed of Taihu Lake Basin...
May 25, 2018: Environmental Science and Pollution Research International
Justin Moat, Steven P Bachman, Richard Field, Doreen S Boyd
The 'modifiable areal unit problem' is prevalent across many aspects of spatial analysis within ecology and conservation. The problem is particularly manifest when calculating metrics for extinction risk estimation, for example, area of occupancy (AOO). Although embedded into the International Union for the Conservation of Nature (IUCN) Red List criteria, AOO is often not used or is poorly applied. Here we evaluate new and existing methods for calculating AOO from occurrence records and present a method for determining the minimum AOO using a uniform grid...
May 23, 2018: Conservation Biology: the Journal of the Society for Conservation Biology
Jukka Pappinen, Päivi Laukkanen-Nevala, Pekka Mäntyselkä, Jouni Kurola
BACKGROUND: In Finland, hospital districts (HD) are required by law to determine the level and availability of Emergency Medical Services (EMS) for each 1-km2 sized area (cell) within their administrative area. The cells are currently categorised into five risk categories based on the predicted number of missions. Methodological defects and insufficient instructions have led to incomparability between EMS services. The aim of this study was to describe a new, nationwide method for categorising the cells, analyse EMS response time data and describe possible differences in mission profiles between the new risk category areas...
May 15, 2018: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine
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