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Grid cells

Nicolas Lemercier, Volker Middel, Didier Hentsch, Serge Taubert, Masanari Takamiya, Tanja Beil, Jean-Luc Vonesch, Tilo Baumbach, Patrick Schultz, Claude Antony, Uwe Strähle
Many areas of biological research demand the combined use of different imaging modalities to cover a wide range of magnifications and measurements or to place fluorescent patterns into an ultrastructural context. A technically difficult problem is the efficient specimen transfer between different imaging modalities without losing the coordinates of the regions-of-interest (ROI). Here, we report a new and highly sensitive integrated system that combines a custom designed microscope with an ultramicrotome for in-resin-fluorescence detection in blocks, ribbons and sections on EM-grids...
October 19, 2017: Scientific Reports
Yoshifumi Nishimura, Hiromi Nakai
A low-computational-cost algorithm and its parallel implementation for periodic divide-and-conquer density-functional tight-binding (DC-DFTB) calculations are presented. The developed algorithm enables rapid computation of the interaction between atomic partial charges, which is the bottleneck for applications to large systems, by means of multipole- and interpolation-based approaches for long- and short-range contributions. The numerical errors of energy and forces with respect to the conventional Ewald-based technique can be under the control of the multipole expansion order, level of unit cell replication, and interpolation grid size...
October 18, 2017: Journal of Computational Chemistry
Kees de Hoogh, Harris Héritier, Massimo Stafoggia, Nino Künzli, Itai Kloog
Spatiotemporal resolved models were developed predicting daily fine particulate matter (PM2.5) concentrations across Switzerland from 2003 to 2013. Relatively sparse PM2.5 monitoring data was supplemented by imputing PM2.5 concentrations at PM10 sites, using PM2.5/PM10 ratios at co-located sites. Daily PM2.5 concentrations were first estimated at a 1 × 1km resolution across Switzerland, using Multiangle Implementation of Atmospheric Correction (MAIAC) spectral aerosol optical depth (AOD) data in combination with spatiotemporal predictor data in a four stage approach...
October 13, 2017: Environmental Pollution
Maxine Perrin, Manon Robillard, Annie Roy-Charland
This study examined eye movements during a visual search task as well as cognitive abilities within three age groups. The aim was to explore scanning patterns across symbol grids and to better understand the impact of symbol location in AAC displays on speed and accuracy of symbol selection. For the study, 60 students were asked to locate a series of symbols on 16 cell grids. The EyeLink 1000 was used to measure eye movements, accuracy, and response time. Accuracy was high across all cells. Participants had faster response times, longer fixations, and more frequent fixations on symbols located in the middle of the grid...
October 10, 2017: Augmentative and Alternative Communication: AAC
Annika Wenz, Kirsten Borchers, Günter E M Tovar, Petra Kluger
Though bioprinting is a forward-looking approach in bone tissue engineering, the development of bioinks which are on the one hand processable with the chosen printing technique, and on the other hand possess the relevant mechanical as well as osteoconductive features remains a challenge. In the present study, polymer solutions based on methacrylated gelatin and methacrylated hyaluronic acid modified with hydroxyapatite particles (5 wt%) were prepared. Encapsulation of primary human adipose-derived stem cells in the hydroxyapatite-containing gels and culture for 28 days resulted in a storage moduli significantly increased to126...
October 9, 2017: Biofabrication
Jean-Marie Cariolet, Morgane Colombert, Marc Vuillet, Youssef Diab
Recent studies report that outdoor air pollution will become the main environmental cause of premature death over the next few decades (OECD, 2012; WHO, 2014; World Bank, 2016). Cities are considered hot spots and urban populations are particularly exposed. There is therefore an urgent need to adapt urban systems and urban design to tackle this issue. While most European cities have introduced measures to reduce emissions, action is still required to reduce concentrations and exposure, and a holistic approach to urban design is badly needed...
October 5, 2017: Science of the Total Environment
Pavel Chernyavskiy, Mark P Little, Philip S Rosenberg
Age-period-cohort (APC) models are widely used to analyze population-level rates, particularly cancer incidence and mortality. These models are used for descriptive epidemiology, comparative risk analysis, and extrapolating future disease burden. Traditional APC models have 2 major limitations: (1) they lack parsimony because they require estimation of deviations from linear trends for each level of age, period, and cohort; and (2) rates observed at similar ages, periods, and cohorts are treated as independent, ignoring any correlations between them that may lead to biased parameter estimates and inefficient standard errors...
October 4, 2017: Statistics in Medicine
Kazuko Omodaka, Tsutomu Kikawa, Yukihiro Shiga, Satoru Tsuda, Yu Yokoyama, Haruka Sato, Junko Ohuchi, Akiko Matsumoto, Hidetoshi Takahashi, Masahiro Akiba, Toru Nakazawa
PURPOSE: To identify sectors of the optical coherence tomography (OCT) macular map that could be used to effectively assess structural progression in patients with normal-tension glaucoma (NTG). METHODS: This study examined 117 eyes of 117 NTG patients to establish axonal tract-dependent macular sectors, and also examined a separate group of 122 eyes of 81 NTG patients to evaluate the ability of these sectors to reveal glaucoma progression. Longitudinal data, including macular maps from at least 5 OCT examinations performed over at least 2 years, was available for all patients in this group...
2017: PloS One
Tiziano D'Albis, Richard Kempter
Spatial cognition in mammals is thought to rely on the activity of grid cells in the entorhinal cortex, yet the fundamental principles underlying the origin of grid-cell firing are still debated. Grid-like patterns could emerge via Hebbian learning and neuronal adaptation, but current computational models remained too abstract to allow direct confrontation with experimental data. Here, we propose a single-cell spiking model that generates grid firing fields via spike-rate adaptation and spike-timing dependent plasticity...
October 2017: PLoS Computational Biology
Kimberly L Stachenfeld, Matthew M Botvinick, Samuel J Gershman
A cognitive map has long been the dominant metaphor for hippocampal function, embracing the idea that place cells encode a geometric representation of space. However, evidence for predictive coding, reward sensitivity and policy dependence in place cells suggests that the representation is not purely spatial. We approach this puzzle from a reinforcement learning perspective: what kind of spatial representation is most useful for maximizing future reward? We show that the answer takes the form of a predictive representation...
October 2, 2017: Nature Neuroscience
Kostadinka Bizheva, Bingyao Tan, Benjamin MacLellan, Zohreh Hosseinaee, Erik Mason, Denise Hileeto, Luigina Sorbara
A research-grade OCT system was used to image in-vivo and without contact with the tissue, the cellular structure and microvasculature of the healthy human corneo-scleral limbus. The OCT system provided 0.95 µm axial and 4 µm (2 µm) lateral resolution in biological tissue depending on the magnification of the imaging objective. Cross-sectional OCT images acquired tangentially from the inferior limbus showed reflective, loop-like features that correspond to the fibrous folds of the palisades of Vogt (POV)...
September 1, 2017: Biomedical Optics Express
Chenglin Miao, Qichen Cao, May-Britt Moser, Edvard I Moser
The medial entorhinal cortex (MEC) contains several discrete classes of GABAergic interneurons, but their specific contributions to spatial pattern formation in this area remain elusive. We employed a pharmacogenetic approach to silence either parvalbumin (PV)- or somatostatin (SOM)-expressing interneurons while MEC cells were recorded in freely moving mice. PV-cell silencing antagonized the hexagonally patterned spatial selectivity of grid cells, especially in layer II of MEC. The impairment was accompanied by reduced speed modulation in colocalized speed cells...
October 19, 2017: Cell
Majid Pakdel, Saeid Jalilzadeh
In this paper a novel packed U cell (PUC) based multilevel grid connected inverter is proposed. Unlike the U cell arrangement which consists of two power switches and one capacitor, in the proposed converter topology a lower DC power supply from renewable energy resources such as photovoltaic arrays (PV) is used as a base power source. The proposed topology offers higher efficiency and lower cost using a small number of power switches and a lower DC power source which is supplied from renewable energy resources...
September 29, 2017: Scientific Reports
Helene Schmidt, Anjali Gour, Jakob Straehle, Kevin M Boergens, Michael Brecht, Moritz Helmstaedter
Research on neuronal connectivity in the cerebral cortex has focused on the existence and strength of synapses between neurons, and their location on the cell bodies and dendrites of postsynaptic neurons. The synaptic architecture of individual presynaptic axonal trees, however, remains largely unknown. Here we used dense reconstructions from three-dimensional electron microscopy in rats to study the synaptic organization of local presynaptic axons in layer 2 of the medial entorhinal cortex, the site of grid-like spatial representations...
September 28, 2017: Nature
Nick Golding, Roy Burstein, Joshua Longbottom, Annie J Browne, Nancy Fullman, Aaron Osgood-Zimmerman, Lucas Earl, Samir Bhatt, Ewan Cameron, Daniel C Casey, Laura Dwyer-Lindgren, Tamer H Farag, Abraham D Flaxman, Maya S Fraser, Peter W Gething, Harry S Gibson, Nicholas Graetz, L Kendall Krause, Xie Rachel Kulikoff, Stephen S Lim, Bonnie Mappin, Chloe Morozoff, Robert C Reiner, Amber Sligar, David L Smith, Haidong Wang, Daniel J Weiss, Christopher J L Murray, Catherine L Moyes, Simon I Hay
BACKGROUND: During the Millennium Development Goal (MDG) era, many countries in Africa achieved marked reductions in under-5 and neonatal mortality. Yet the pace of progress toward these goals substantially varied at the national level, demonstrating an essential need for tracking even more local trends in child mortality. With the adoption of the Sustainable Development Goals (SDGs) in 2015, which established ambitious targets for improving child survival by 2030, optimal intervention planning and targeting will require understanding of trends and rates of progress at a higher spatial resolution...
September 25, 2017: Lancet
Asuka Yuda, Christopher A McCulloch
The generation of cell extensions is critical for matrix remodeling in tissue invasion by cancer cells, but current methods for identifying molecules that regulate cell extension formation and matrix remodeling are not well adapted for screening purposes. We applied a grid-supported, floating collagen gel system (~100 Pa stiffness) to examine cell extension formation, collagen compaction, and collagen degradation in a single assay. With the use of cultured diploid fibroblasts, a fibroblast cell line, and two cancer cell lines, we found that compared with attached collagen gels (~2800 Pa), the mean number and length of cell extensions were respectively greater in the floating gels...
September 1, 2017: SLAS Discovery
C A Suarez-Mendez, C Ras, S A Wahl
BACKGROUND: Natural and industrial environments are dynamic with respect to substrate availability and other conditions like temperature and pH. Especially, metabolism is strongly affected by changes in the extracellular space. Here we study the dynamic flux of central carbon metabolism and storage carbohydrate metabolism under dynamic feast/famine conditions in Saccharomyces cerevisiae. RESULTS: The metabolic flux reacts fast and sensitive to cyclic perturbations in substrate availability...
September 25, 2017: Microbial Cell Factories
Shahla Khalili, Saied Nouri Khorasani, Mohammad Razavi, Batol Hashemi Beni, Fariba Heydari, Ali Tamayol
This research studies the effect of using a grid-like pattern as a collector on increasing the pore size of the electrospun gelatin/cellulose acetate/elastin scaffolds. The morphological study showed an enlargement in pore size and a decline in fiber diameter in comparison with the scaffold fabricated using conventional flat sheet collectors. The use of the pattern increased the swelling ratio and degradation rate of the scaffold. Investigating the tensile properties of scaffolds revealed that the patterned collector increased the elongation at break up to 145%...
September 25, 2017: Journal of Biomedical Materials Research. Part A
Ainslie L K Derrick-Roberts, Matilda R Jackson, Carmen E Pyragius, Sharon Byers
Mucopolysaccharidosis type I (MPS I) is the most common form of the MPS group of genetic diseases. MPS I results from a deficiency in the lysosomal enzyme α-l-iduronidase, leading to accumulation of undegraded heparan and dermatan sulphate glycosaminoglycan (GAG) chains in patient cells. MPS children suffer from multiple organ failure and die in their teens to early twenties. In particular, MPS I children also suffer from profound mental retardation and skeletal disease that restricts growth and movement. Neither brain nor skeletal disease is adequately treated by current therapy approaches...
February 23, 2017: Diseases (Basel)
Ali Noorafshan, Fatemeh Karimi, Ali-Mohammad Kamali, Saied Karbalay-Doust, Mohammad Nami
The present study examined the consequences of rapid eye-movement sleep-deprivation (REM-SD) with or without curcumin treatment. The outcome measures comprised quantitative features in the three-dimensional reconstructed (3DR) CA1 and dentate gyrus in experimental and control animals using stereological procedures. Male rats were arbitrarily assigned to nine groups based on the intervention and treatment administered including: 1-cage control+distilled water, 2-cage control+curcumin (100mg/kg/day), 3-cage control+olive oil, 4-REM-SD+distilled water, 5-REM-SD+curcumin, 6-REM-SD+olive oil, 7-grid-floor control+distilled water, 8-grid-floor control+curcumin, and 9-grid-floor control+olive oil...
September 17, 2017: Life Sciences
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