A process analysis of the CA3 subregion of the hippocampus

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Raymond PIERRE Kesner

2013-05-01

Full Text Available AbstractFrom a behavioral perspective the CA3a,b subregion of the hippocampus plays an important role in the encoding of new spatial information within short-term memory with a duration of seconds and minutes. This can easily be observed in tasks that require rapid encoding, novelty detection, 1-trial short- term or working memory, and 1-trial cued recall primarily for spatial information. These are tasks that have been assumed to reflect the operations of episodic memory and require interactions between CA3a,b and the dentate gyrus via mossy fiber inputs into the CA3a,b. The CA3a,b is also important for encoding of spatial information requiring the acquisition of arbitrary and relational associations. All these tasks are assumed to operate within an autoassociative network function of the CA3 region. The CA3a,b also supports retrieval of short-term memory information based on a spatial pattern completion process. Based on afferent inputs into CA3a,b from the dentate gyrus (DG via mossy fibers and afferents from the entorhinal cortex into CA3a,b as well as reciprocal connections with the septum, CA3a,b can bias the process of encoding utilizing the operation of spatial pattern separation and the process of retrieval utilizing the operation of pattern completion. The CA3a,b also supports sequential processing of information in cooperation with CA1 based on the Schaffer collateral output from CA3a,b to CA1. The CA3c function is in part based on modulation of the DG in supporting pattern separation processes.

Computational hologram synthesis and representation on spatial light modulators for real-time 3D holographic imaging

International Nuclear Information System (INIS)

Reichelt, Stephan; Leister, Norbert

2013-01-01

In dynamic computer-generated holography that utilizes spatial light modulators, both hologram synthesis and hologram representation are essential in terms of fast computation and high reconstruction quality. For hologram synthesis, i.e. the computation step, Fresnel transform based or point-source based raytracing methods can be applied. In the encoding step, the complex wave-field has to be optimally represented by the SLM with its given modulation capability. For proper hologram reconstruction that implies a simultaneous and independent amplitude and phase modulation of the input wave-field by the SLM. In this paper, we discuss full complex hologram representation methods on SLMs by considering inherent SLM parameter such as modulation type and bit depth on their reconstruction performance such as diffraction efficiency and SNR. We review the three implementation schemes of Burckhardt amplitude-only representation, phase-only macro-pixel representation, and two-phase interference representation. Besides the optical performance we address their hardware complexity and required computational load. Finally, we experimentally demonstrate holographic reconstructions of different representation schemes as obtained by functional prototypes utilizing SeeReal's viewing-window holographic display technology. The proposed hardware implementations enable a fast encoding of complex-valued hologram data and thus will pave the way for commercial real-time holographic 3D imaging in the near future.

Linguistic and Perceptual Mapping in Spatial Representations: An Attentional Account.

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Valdés-Conroy, Berenice; Hinojosa, José A; Román, Francisco J; Romero-Ferreiro, Verónica

2018-03-01

Building on evidence for embodied representations, we investigated whether Spanish spatial terms map onto the NEAR/FAR perceptual division of space. Using a long horizontal display, we measured congruency effects during the processing of spatial terms presented in NEAR or FAR space. Across three experiments, we manipulated the task demands in order to investigate the role of endogenous attention in linguistic and perceptual space mapping. We predicted congruency effects only when spatial properties were relevant for the task (reaching estimation task, Experiment 1) but not when attention was allocated to other features (lexical decision, Experiment 2; and color, Experiment 3). Results showed faster responses for words presented in Near-space in all experiments. Consistent with our hypothesis, congruency effects were observed only when a reaching estimate was requested. Our results add important evidence for the role of top-down processing in congruency effects from embodied representations of spatial terms. Copyright © 2017 Cognitive Science Society, Inc.

Spatially variant morphological restoration and skeleton representation.

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Bouaynaya, Nidhal; Charif-Chefchaouni, Mohammed; Schonfeld, Dan

2006-11-01

The theory of spatially variant (SV) mathematical morphology is used to extend and analyze two important image processing applications: morphological image restoration and skeleton representation of binary images. For morphological image restoration, we propose the SV alternating sequential filters and SV median filters. We establish the relation of SV median filters to the basic SV morphological operators (i.e., SV erosions and SV dilations). For skeleton representation, we present a general framework for the SV morphological skeleton representation of binary images. We study the properties of the SV morphological skeleton representation and derive conditions for its invertibility. We also develop an algorithm for the implementation of the SV morphological skeleton representation of binary images. The latter algorithm is based on the optimal construction of the SV structuring element mapping designed to minimize the cardinality of the SV morphological skeleton representation. Experimental results show the dramatic improvement in the performance of the SV morphological restoration and SV morphological skeleton representation algorithms in comparison to their translation-invariant counterparts.

Spatial representation in the hippocampal formation: a history.

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Moser, Edvard I; Moser, May-Britt; McNaughton, Bruce L

2017-10-26

Since the first place cell was recorded and the cognitive-map theory was subsequently formulated, investigation of spatial representation in the hippocampal formation has evolved in stages. Early studies sought to verify the spatial nature of place cell activity and determine its sensory origin. A new epoch started with the discovery of head direction cells and the realization of the importance of angular and linear movement-integration in generating spatial maps. A third epoch began when investigators turned their attention to the entorhinal cortex, which led to the discovery of grid cells and border cells. This review will show how ideas about integration of self-motion cues have shaped our understanding of spatial representation in hippocampal-entorhinal systems from the 1970s until today. It is now possible to investigate how specialized cell types of these systems work together, and spatial mapping may become one of the first cognitive functions to be understood in mechanistic detail.

The spatial representation of market information

NARCIS (Netherlands)

DeSarbo, WS; Degeratu, AM; Wedel, M; Saxton, MK

2001-01-01

To be used effectively, market knowledge and information must be structured and represented in ways that are parsimonious and conducive to efficient managerial decision making. This manuscript proposes a new latent structure spatial model for the representation of market information that meets this

EnzyNet: enzyme classification using 3D convolutional neural networks on spatial representation.

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Amidi, Afshine; Amidi, Shervine; Vlachakis, Dimitrios; Megalooikonomou, Vasileios; Paragios, Nikos; Zacharaki, Evangelia I

2018-01-01

During the past decade, with the significant progress of computational power as well as ever-rising data availability, deep learning techniques became increasingly popular due to their excellent performance on computer vision problems. The size of the Protein Data Bank (PDB) has increased more than 15-fold since 1999, which enabled the expansion of models that aim at predicting enzymatic function via their amino acid composition. Amino acid sequence, however, is less conserved in nature than protein structure and therefore considered a less reliable predictor of protein function. This paper presents EnzyNet, a novel 3D convolutional neural networks classifier that predicts the Enzyme Commission number of enzymes based only on their voxel-based spatial structure. The spatial distribution of biochemical properties was also examined as complementary information. The two-layer architecture was investigated on a large dataset of 63,558 enzymes from the PDB and achieved an accuracy of 78.4% by exploiting only the binary representation of the protein shape. Code and datasets are available at https://github.com/shervinea/enzynet.

NMDA Signaling in CA1 Mediates Selectively the Spatial Component of Episodic Memory

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Place, Ryan; Lykken, Christy; Beer, Zachery; Suh, Junghyup; McHugh, Thomas J.; Tonegawa, Susumu; Eichenbaum, Howard; Sauvage, Magdalena M.

2012-01-01

Recent studies focusing on the memory for temporal order have reported that CA1 plays a critical role in the memory for the sequences of events, in addition to its well-described role in spatial navigation. In contrast, CA3 was found to principally contribute to the memory for the association of items with spatial or contextual information in…

Spatial Representation of Ordinal Information

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Meng eZhang

2016-04-01

Full Text Available Right hand responds faster than left hand when shown larger numbers and vice-versa when shown smaller numbers (the SNARC effect. Accumulating evidence suggests that the SNARC effect may not be exclusive for numbers and can be extended to other ordinal sequences (e.g., months or letters in the alphabet as well. In this study, we tested the SNARC effect with a non-numerically ordered sequence: The Chinese notations for the color spectrum (Red, Orange, Yellow, Green, Blue, Indigo, and Violet. Chinese color word sequence reserves relatively weak ordinal information, because each element color in the sequence normally appears in non-sequential contexts, making it ideal to test the spatial organization of sequential information that was stored in the long-term memory. This study found a reliable SNARC-like effect for Chinese color words (deciding whether the presented color word was before or after the reference color word green, suggesting that, without access to any quantitative information or exposure to any previous training, ordinal representation can still activate a sense of space. The results support that weak ordinal information without quantitative magnitude encoded in the long-term memory can activate spatial representation in a comparison task.

Spatial Representation of Ordinal Information.

Science.gov (United States)

Zhang, Meng; Gao, Xuefei; Li, Baichen; Yu, Shuyuan; Gong, Tianwei; Jiang, Ting; Hu, Qingfen; Chen, Yinghe

2016-01-01

Right hand responds faster than left hand when shown larger numbers and vice-versa when shown smaller numbers (the SNARC effect). Accumulating evidence suggests that the SNARC effect may not be exclusive for numbers and can be extended to other ordinal sequences (e.g., months or letters in the alphabet) as well. In this study, we tested the SNARC effect with a non-numerically ordered sequence: the Chinese notations for the color spectrum (Red, Orange, Yellow, Green, Blue, Indigo, and Violet). Chinese color word sequence reserves relatively weak ordinal information, because each element color in the sequence normally appears in non-sequential contexts, making it ideal to test the spatial organization of sequential information that was stored in the long-term memory. This study found a reliable SNARC-like effect for Chinese color words (deciding whether the presented color word was before or after the reference color word "green"), suggesting that, without access to any quantitative information or exposure to any previous training, ordinal representation can still activate a sense of space. The results support that weak ordinal information without quantitative magnitude encoded in the long-term memory can activate spatial representation in a comparison task.

Perirhinal cortical inactivation impairs object-in-place memory and disrupts task-dependent firing in hippocampal CA1, but not in CA3.

Science.gov (United States)

Lee, Inah; Park, Seong-Beom

2013-01-01

Objects and their locations can associatively define an event and a conjoint representation of object-place can form an event memory. Remembering how to respond to a certain object in a spatial context is dependent on both hippocampus and perirhinal cortex (PER). However, the relative functional contributions of the two regions are largely unknown in object-place associative memory. We investigated the PER influence on hippocampal firing in a goal-directed object-place memory task by comparing the firing patterns of CA1 and CA3 of the dorsal hippocampus between conditions of PER muscimol inactivation and vehicle control infusions. Rats were required to choose one of the two objects in a specific spatial context (regardless of the object positions in the context), which was shown to be dependent on both hippocampus and PER. Inactivation of PER with muscimol (MUS) severely disrupted performance of well-trained rats, resulting in response bias (i.e., choosing any object on a particular side). MUS did not significantly alter the baseline firing rates of hippocampal neurons. We measured the similarity in firing patterns between two trial conditions in which the same target objects were chosen on opposite sides within the same arm [object-in-place (O-P) strategy] and compared the results with the similarity in firing between two trial conditions in which the rat chose any object encountered on a particular side [response-in-place (R-P) strategy]. We found that the similarity in firing patterns for O-P trials was significantly reduced with MUS compared to control conditions (CTs). Importantly, this was largely because MUS injections affected the O-P firing patterns in CA1 neurons, but not in CA3. The results suggest that PER is critical for goal-directed organization of object-place associative memory in the hippocampus presumably by influencing how object information is associated with spatial information in CA1 according to task demand.

Perirhinal cortical inactivation impairs object-in-place memory and disrupts task-dependent firing in hippocampal CA1, but not in CA3

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Inah eLee

2013-08-01

Full Text Available Objects and their locations can associatively define an event and a conjoint representation of object-place can form an event memory. Remembering how to respond to a certain object in a spatial context is dependent on both hippocampus and perirhinal cortex (PER. However, the relative functional contributions of the two regions are largely unknown in object-place associative memory. We investigated the PER influence on hippocampal firing in a goal-directed object-place memory task by comparing the firing patterns of CA1 and CA3 of the dorsal hippocampus between conditions of PER muscimol inactivation and vehicle control infusions. Rats were required to choose one of the two objects in a specific spatial context (regardless of the object positions in the context, which was shown to be dependent on both hippocampus and PER. Inactivation of PER with muscimol (MUS severely disrupted performance of well-trained rats, resulting in response bias (i.e., choosing any object on a particular side. MUS did not significantly alter the baseline firing rates of hippocampal neurons. We measured the similarity in firing patterns between two trial conditions in which the same target objects were chosen on opposite sides within the same arm (object-in-place strategy and compared the results with the similarity in firing between two trial conditions in which the rat chose any object encountered on a particular side (response-in-place strategy. We found that the similarity in firing patterns for object-in-place trials was significantly reduced with MUS compared to control conditions. Importantly, this was largely because MUS injections affected the object-in-place firing patterns in CA1 neurons, but not in CA3. The results suggest that PER is critical for goal-directed organization of object-place associative memory in the hippocampus presumably by influencing how object information is associated with spatial information in CA1 according to task demand.

Language, Perception, and the Schematic Representation of Spatial Relations

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Amorapanth, Prin; Kranjec, Alexander; Bromberger, Bianca; Lehet, Matthew; Widick, Page; Woods, Adam J.; Kimberg, Daniel Y.; Chatterjee, Anjan

2012-01-01

Schemas are abstract nonverbal representations that parsimoniously depict spatial relations. Despite their ubiquitous use in maps and diagrams, little is known about their neural instantiation. We sought to determine the extent to which schematic representations are neurally distinguished from language on the one hand, and from rich perceptual…

Dock Sud's environmental pollution: Spatial representations, space representation and spatial practices in peripheral neighborhoods

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Sandra Valeria Ursino

2012-01-01

Full Text Available In this article, we present some of the results and argumentative lines used in the analysis of the field work carried out in the neighborhoods of Porst, Danubio and Villa Inflamable, in the Dock Sud area, located in the district of Avellaneda, province de Buenos Aires, during 2010 and 2011. Within this framework, we observed and recorded the inhabitants' usual routes around the neighborhood, which is environmentally polluted but which has also been symbolically appropriated. Along these lines then, our general aim was to learn about social representations, representation spaces and the spatial practices of the inhabitants of the most affected neighborhoods of Dock Sud due to the area's environmental issues. To this end, there was a reconstruction of the subjects' practices in the neighborhood, of the hegemonic discourse about the pollution in this place and, finally, the population's conflict and struggle practices

Ventral tegmental area disruption selectively affects CA1/CA2 but not CA3 place fields during a differential reward working memory task.

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Martig, Adria K; Mizumori, Sheri J Y

2011-02-01

Hippocampus (HPC) receives dopaminergic (DA) projections from the ventral tegmental area (VTA) and substantia nigra. These inputs appear to provide a modulatory signal that influences HPC dependent behaviors and place fields. We examined how efferent projections from VTA to HPC influence spatial working memory and place fields when the reward context changes. CA1 and CA3 process environmental context changes differently and VTA preferentially innervates CA1. Given these anatomical data and electrophysiological evidence that implicate DA in reward processing, we predicted that CA1 place fields would respond more strongly to both VTA disruption and changes in the reward context than CA3 place fields. Rats (N = 9) were implanted with infusion cannula targeting VTA and recording tetrodes aimed at HPC. Then they were tested on a differential reward, win-shift working memory task. One recording session consisted of 5 baseline and 5 manipulation trials during which place cells in CA1/CA2 (N = 167) and CA3 (N = 94) were recorded. Prior to manipulation trials rats were infused with either baclofen or saline and then subjected to control or reward conditions during which the learned locations of large and small reward quantities were reversed. VTA disruption resulted in an increase in errors, and in CA1/CA2 place field reorganization. There were no changes in any measures of CA3 place field stability during VTA disruption. Reward manipulations did not affect performance or place field stability in CA1/CA2 or CA3; however, changes in the reward locations "rescued" performance and place field stability in CA1/CA2 when VTA activity was compromised, perhaps by trigging compensatory mechanisms. These data support the hypothesis that VTA contributes to spatial working memory performance perhaps by maintaining place field stability selectively in CA1/CA2. Copyright © 2009 Wiley-Liss, Inc.

Impacts of spatial resolution and representation of flow connectivity on large-scale simulation of floods

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C. M. R. Mateo

2017-10-01

Full Text Available Global-scale river models (GRMs are core tools for providing consistent estimates of global flood hazard, especially in data-scarce regions. Due to former limitations in computational power and input datasets, most GRMs have been developed to use simplified representations of flow physics and run at coarse spatial resolutions. With increasing computational power and improved datasets, the application of GRMs to finer resolutions is becoming a reality. To support development in this direction, the suitability of GRMs for application to finer resolutions needs to be assessed. This study investigates the impacts of spatial resolution and flow connectivity representation on the predictive capability of a GRM, CaMa-Flood, in simulating the 2011 extreme flood in Thailand. Analyses show that when single downstream connectivity (SDC is assumed, simulation results deteriorate with finer spatial resolution; Nash–Sutcliffe efficiency coefficients decreased by more than 50 % between simulation results at 10 km resolution and 1 km resolution. When multiple downstream connectivity (MDC is represented, simulation results slightly improve with finer spatial resolution. The SDC simulations result in excessive backflows on very flat floodplains due to the restrictive flow directions at finer resolutions. MDC channels attenuated these effects by maintaining flow connectivity and flow capacity between floodplains in varying spatial resolutions. While a regional-scale flood was chosen as a test case, these findings should be universal and may have significant impacts on large- to global-scale simulations, especially in regions where mega deltas exist.These results demonstrate that a GRM can be used for higher resolution simulations of large-scale floods, provided that MDC in rivers and floodplains is adequately represented in the model structure.

Impacts of spatial resolution and representation of flow connectivity on large-scale simulation of floods

Science.gov (United States)

Mateo, Cherry May R.; Yamazaki, Dai; Kim, Hyungjun; Champathong, Adisorn; Vaze, Jai; Oki, Taikan

2017-10-01

Global-scale river models (GRMs) are core tools for providing consistent estimates of global flood hazard, especially in data-scarce regions. Due to former limitations in computational power and input datasets, most GRMs have been developed to use simplified representations of flow physics and run at coarse spatial resolutions. With increasing computational power and improved datasets, the application of GRMs to finer resolutions is becoming a reality. To support development in this direction, the suitability of GRMs for application to finer resolutions needs to be assessed. This study investigates the impacts of spatial resolution and flow connectivity representation on the predictive capability of a GRM, CaMa-Flood, in simulating the 2011 extreme flood in Thailand. Analyses show that when single downstream connectivity (SDC) is assumed, simulation results deteriorate with finer spatial resolution; Nash-Sutcliffe efficiency coefficients decreased by more than 50 % between simulation results at 10 km resolution and 1 km resolution. When multiple downstream connectivity (MDC) is represented, simulation results slightly improve with finer spatial resolution. The SDC simulations result in excessive backflows on very flat floodplains due to the restrictive flow directions at finer resolutions. MDC channels attenuated these effects by maintaining flow connectivity and flow capacity between floodplains in varying spatial resolutions. While a regional-scale flood was chosen as a test case, these findings should be universal and may have significant impacts on large- to global-scale simulations, especially in regions where mega deltas exist.These results demonstrate that a GRM can be used for higher resolution simulations of large-scale floods, provided that MDC in rivers and floodplains is adequately represented in the model structure.

No functional role of attention-based rehearsal in maintenance of spatial working memory representations.

Science.gov (United States)

Belopolsky, Artem V; Theeuwes, Jan

2009-10-01

The present study systematically examined the role of attention in maintenance of spatial representations in working memory as proposed by the attention-based rehearsal hypothesis [Awh, E., Jonides, J., & Reuter-Lorenz, P. A. (1998). Rehearsal in spatial working memory. Journal of Experimental Psychology--Human Perception and Performance, 24(3), 780-790]. Three main issues were examined. First, Experiments 1-3 demonstrated that inhibition and not facilitation of visual processing is often observed at the memorized location during the retention interval. This inhibition was caused by keeping a location in memory and not by the exogenous nature of the memory cue. Second, Experiment 4 showed that inhibition of the memorized location does not lead to any significant impairment in memory accuracy. Finally, Experiment 5 connected current results to the previous findings and demonstrated facilitation of processing at the memorized location. Importantly, facilitation of processing did not lead to more accurate memory performance. The present results challenge the functional role of attention in maintenance of spatial working memory representations.

Continuous spatial representations in the olfactory bulb may reflect perceptual categories

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Benjamin eAuffarth

2011-10-01

Full Text Available In sensory processing of odors, the olfactory bulb is an important relay station, where odor representations are noise-filtered, sharpened, and possibly re-organized. An organization by perceptual qualities has been found previously in the piriform cortex, however several recent studies indicate that the olfactory bulb code reflects behaviorally relevant dimensions spatially as well as at the population level. We apply a statistical analysis on 2-deoxyglucose images, taken over the entire bulb of glomerular layer of the rat, in order to see how the recognition of odors in the nose is translated into a map of odor quality in the brain. We first confirm previous studies that the first principal component could be related to pleasantness, however the next higher principal components are not directly clear. We then find mostly continuous spatial representations for perceptual categories. We compare the space spanned by spatial and population codes to human reports of perceptual similarity between odors and our results suggest that perceptual categories could be already embedded in glomerular activations and that spatial representations give a better match than population codes. This suggests that human and rat perceptual dimensions of odorant coding are related and indicates that perceptual qualities could be represented as continuous spatial codes of the olfactory bulb glomerulus population.

Thinking Egyptian: Active Models for Understanding Spatial Representation.

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Schiferl, Ellen

This paper highlights how introductory textbooks on Egyptian art inhibit understanding by reinforcing student preconceptions, and demonstrates another approach to discussing space with a classroom exercise and software. The alternative approach, an active model for spatial representation, introduced here was developed by adapting classroom…

Spatial Representations in Local Field Potential Activity of Primate Anterior Intraparietal Cortex (AIP.

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Sebastian J Lehmann

Full Text Available The execution of reach-to-grasp movements in order to interact with our environment is an important subset of the human movement repertoire. To coordinate such goal-directed movements, information about the relative spatial position of target and effector (in this case the hand has to be continuously integrated and processed. Recently, we reported the existence of spatial representations in spiking-activity of the cortical fronto-parietal grasp network (Lehmann & Scherberger 2013, and in particular in the anterior intraparietal cortex (AIP. To further investigate the nature of these spatial representations, we explored in two rhesus monkeys (Macaca mulatta how different frequency bands of the local field potential (LFP in AIP are modulated by grip type, target position, and gaze position, during the planning and execution of reach-to-grasp movements. We systematically varied grasp type, spatial target, and gaze position and found that both spatial and grasp information were encoded in a variety of frequency bands (1-13Hz, 13-30Hz, 30-60Hz, and 60-100Hz, respectively. Whereas the representation of grasp type strongly increased towards and during movement execution, spatial information was represented throughout the task. Both spatial and grasp type representations could be readily decoded from all frequency bands. The fact that grasp type and spatial (reach information was found not only in spiking activity, but also in various LFP frequency bands of AIP, might significantly contribute to the development of LFP-based neural interfaces for the control of upper limb prostheses.

Behavioral and Neural Representations of Spatial Directions across Words, Schemas, and Images.

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Weisberg, Steven M; Marchette, Steven A; Chatterjee, Anjan

2018-05-23

Modern spatial navigation requires fluency with multiple representational formats, including visual scenes, signs, and words. These formats convey different information. Visual scenes are rich and specific but contain extraneous details. Arrows, as an example of signs, are schematic representations in which the extraneous details are eliminated, but analog spatial properties are preserved. Words eliminate all spatial information and convey spatial directions in a purely abstract form. How does the human brain compute spatial directions within and across these formats? To investigate this question, we conducted two experiments on men and women: a behavioral study that was preregistered and a neuroimaging study using multivoxel pattern analysis of fMRI data to uncover similarities and differences among representational formats. Participants in the behavioral study viewed spatial directions presented as images, schemas, or words (e.g., "left"), and responded to each trial, indicating whether the spatial direction was the same or different as the one viewed previously. They responded more quickly to schemas and words than images, despite the visual complexity of stimuli being matched. Participants in the fMRI study performed the same task but responded only to occasional catch trials. Spatial directions in images were decodable in the intraparietal sulcus bilaterally but were not in schemas and words. Spatial directions were also decodable between all three formats. These results suggest that intraparietal sulcus plays a role in calculating spatial directions in visual scenes, but this neural circuitry may be bypassed when the spatial directions are presented as schemas or words. SIGNIFICANCE STATEMENT Human navigators encounter spatial directions in various formats: words ("turn left"), schematic signs (an arrow showing a left turn), and visual scenes (a road turning left). The brain must transform these spatial directions into a plan for action. Here, we investigate

An investigation of spatial representation of pitch in individuals with congenital amusia.

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Lu, Xuejing; Sun, Yanan; Thompson, William Forde

2017-09-01

Spatial representation of pitch plays a central role in auditory processing. However, it is unknown whether impaired auditory processing is associated with impaired pitch-space mapping. Experiment 1 examined spatial representation of pitch in individuals with congenital amusia using a stimulus-response compatibility (SRC) task. For amusic and non-amusic participants, pitch classification was faster and more accurate when correct responses involved a physical action that was spatially congruent with the pitch height of the stimulus than when it was incongruent. However, this spatial representation of pitch was not as stable in amusic individuals, revealed by slower response times when compared with control individuals. One explanation is that the SRC effect in amusics reflects a linguistic association, requiring additional time to link pitch height and spatial location. To test this possibility, Experiment 2 employed a colour-classification task. Participants judged colour while ignoring a concurrent pitch by pressing one of two response keys positioned vertically to be congruent or incongruent with the pitch. The association between pitch and space was found in both groups, with comparable response times in the two groups, suggesting that amusic individuals are only slower to respond to tasks involving explicit judgments of pitch.

Representations and Techniques for 3D Object Recognition and Scene Interpretation

CERN Document Server

Hoiem, Derek

2011-01-01

One of the grand challenges of artificial intelligence is to enable computers to interpret 3D scenes and objects from imagery. This book organizes and introduces major concepts in 3D scene and object representation and inference from still images, with a focus on recent efforts to fuse models of geometry and perspective with statistical machine learning. The book is organized into three sections: (1) Interpretation of Physical Space; (2) Recognition of 3D Objects; and (3) Integrated 3D Scene Interpretation. The first discusses representations of spatial layout and techniques to interpret physi

A Common Representation of Spatial Features Drives Action and Perception

DEFF Research Database (Denmark)

Christiansen, Jens H; Christensen, Jeppe Høy; Grünbaum, Thor

2014-01-01

Spatial features of an object can be specified using two different response types: either by use of symbols or motorically by directly acting upon the object. Is this response dichotomy reflected in a dual representation of the visual world: one for perception and one for action? Previously, symb...... of matching object-processing characteristics is also in agreement with the idea of a common representation driving both response types....

Spatial representations elicit dual-coding effects in mental imagery.

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Verges, Michelle; Duffy, Sean

2009-08-01

Spatial aspects of words are associated with their canonical locations in the real world. Yet little research has tested whether spatial associations denoted in language comprehension generalize to their corresponding images. We directly tested the spatial aspects of mental imagery in picture and word processing (Experiment 1). We also tested whether spatial representations of motion words produce similar perceptual-interference effects as demonstrated by object words (Experiment 2). Findings revealed that words denoting an upward spatial location produced slower responses to targets appearing at the top of the display, whereas words denoting a downward spatial location produced slower responses to targets appearing at the bottom of the display. Perceptual-interference effects did not obtain for pictures or for words lacking a spatial relation. These findings provide greater empirical support for the perceptual-symbols system theory (Barsalou, 1999, 2008). Copyright © 2009 Cognitive Science Society, Inc.

Spatial, Temporal and Spectral Satellite Image Fusion via Sparse Representation

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Song, Huihui

Remote sensing provides good measurements for monitoring and further analyzing the climate change, dynamics of ecosystem, and human activities in global or regional scales. Over the past two decades, the number of launched satellite sensors has been increasing with the development of aerospace technologies and the growing requirements on remote sensing data in a vast amount of application fields. However, a key technological challenge confronting these sensors is that they tradeoff between spatial resolution and other properties, including temporal resolution, spectral resolution, swath width, etc., due to the limitations of hardware technology and budget constraints. To increase the spatial resolution of data with other good properties, one possible cost-effective solution is to explore data integration methods that can fuse multi-resolution data from multiple sensors, thereby enhancing the application capabilities of available remote sensing data. In this thesis, we propose to fuse the spatial resolution with temporal resolution and spectral resolution, respectively, based on sparse representation theory. Taking the study case of Landsat ETM+ (with spatial resolution of 30m and temporal resolution of 16 days) and MODIS (with spatial resolution of 250m ~ 1km and daily temporal resolution) reflectance, we propose two spatial-temporal fusion methods to combine the fine spatial information of Landsat image and the daily temporal resolution of MODIS image. Motivated by that the images from these two sensors are comparable on corresponding bands, we propose to link their spatial information on available Landsat- MODIS image pair (captured on prior date) and then predict the Landsat image from the MODIS counterpart on prediction date. To well-learn the spatial details from the prior images, we use a redundant dictionary to extract the basic representation atoms for both Landsat and MODIS images based on sparse representation. Under the scenario of two prior Landsat

Conceptual spatial representations for indoor mobile robots

OpenAIRE

Zender, Henrik; Mozos, Oscar Martinez; Jensfelt, Patric; Kruijff, Geert-Jan M.; Wolfram, Burgard

2008-01-01

We present an approach for creating conceptual representations of human-made indoor environments using mobile robots. The concepts refer to spatial and functional properties of typical indoor environments. Following findings in cognitive psychology, our model is composed of layers representing maps at different levels of abstraction. The complete system is integrated in a mobile robot endowed with laser and vision sensors for place and object recognition. The system also incorporate...

Visual-Spatial Attention Aids the Maintenance of Object Representations in Visual Working Memory

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Williams, Melonie; Pouget, Pierre; Boucher, Leanne; Woodman, Geoffrey F.

2013-01-01

Theories have proposed that the maintenance of object representations in visual working memory is aided by a spatial rehearsal mechanism. In this study, we used two different approaches to test the hypothesis that overt and covert visual-spatial attention mechanisms contribute to the maintenance of object representations in visual working memory. First, we tracked observers’ eye movements while remembering a variable number of objects during change-detection tasks. We observed that during the blank retention interval, participants spontaneously shifted gaze to the locations that the objects had occupied in the memory array. Next, we hypothesized that if attention mechanisms contribute to the maintenance of object representations, then drawing attention away from the object locations during the retention interval would impair object memory during these change-detection tasks. Supporting this prediction, we found that attending to the fixation point in anticipation of a brief probe stimulus during the retention interval reduced change-detection accuracy even on the trials in which no probe occurred. These findings support models of working memory in which visual-spatial selection mechanisms contribute to the maintenance of object representations. PMID:23371773

Directing spatial attention to locations within remembered and imagined mental representations

Directory of Open Access Journals (Sweden)

Simon G Gosling

2013-04-01

Full Text Available Spatial attention enables us to enhance the processing of items at target locations, at the expense of items presented at irrelevant locations. Many studies have explored the neural correlates of these spatial biases using event-related potentials. More recently some studies have shown that these ERP correlates are also present when subjects search visual short-term memory. This suggests firstly that this type of mental representation retains a spatial organisation that is based upon that of the original percept, and secondly that these attentional biases are flexible and can act to modulate remembered as well as perceptual representations. We aimed to test whether it was necessary for subjects to have actually seen the memoranda at those spatial locations, or whether simply imagining the spatial layout was sufficient to elicit the spatial attention effects. On some trials subjects performed a ‘visual’ search of an array held in visual short-term memory, and upon other trials subjects imagined the items at those spatial locations. We found ERP markers of spatial attention in both the memory-search and the imagery-search conditions. However, there were differences between the conditions, the effect in the memory-search began earlier and included posterior electrode sites. By contrast the ERP effect in the imagery-search condition was apparent only over fronto-central electrode sites and emerged slightly later. Nonetheless, our data demonstrate that it is not necessary for subjects to have ever seen the items at spatial locations for neural markers of spatial attention to be elicited; searching an imaginary spatial layout also triggers spatially-specific attention effects in the ERP data.

SNAP-25 in hippocampal CA3 region is required for long-term memory formation

International Nuclear Information System (INIS)

Hou Qiuling; Gao Xiang; Lu Qi; Zhang Xuehan; Tu Yanyang; Jin Meilei; Zhao Guoping; Yu Lei; Jing Naihe; Li Baoming

2006-01-01

SNAP-25 is a synaptosomal protein of 25 kDa, a key component of synaptic vesicle-docking/fusion machinery, and plays a critical role in exocytosis and neurotransmitter release. We previously reported that SNAP-25 in the hippocampal CA1 region is involved in consolidation of contextual fear memory and water-maze spatial memory (Hou et al. European J Neuroscience, 20: 1593-1603, 2004). SNAP-25 is expressed not only in the CA1 region, but also in the CA3 region, and the SNAP-25 mRNA level in the CA3 region is higher than in the CA1 region. Here, we provide evidence that SNAP-25 in the CA3 region is also involved in learning/memory. Intra-CA3 infusion of SNAP-25 antisense oligonucleotide impaired both long-term contextual fear memory and water-maze spatial memory, with short-term memory intact. Furthermore, the SNAP-25 antisense oligonucleotide suppressed the long-term potentiation (LTP) of field excitatory post-synaptic potential (fEPSP) in the mossy-fiber pathway (DG-CA3 pathway), with no effect on paired-pulse facilitation of the fEPSP. These results are consistent with the notion that SNAP-25 in the hippocampal CA3 region is required for long-term memory formation

Crowding in Visual Working Memory Reveals Its Spatial Resolution and the Nature of Its Representations.

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Tamber-Rosenau, Benjamin J; Fintzi, Anat R; Marois, René

2015-09-01

Spatial resolution fundamentally limits any image representation. Although this limit has been extensively investigated for perceptual representations by assessing how neighboring flankers degrade the perception of a peripheral target with visual crowding, the corresponding limit for representations held in visual working memory (VWM) is unknown. In the present study, we evoked crowding in VWM and directly compared resolution in VWM and perception. Remarkably, the spatial resolution of VWM proved to be no worse than that of perception. However, mixture modeling of errors caused by crowding revealed the qualitatively distinct nature of these representations. Perceptual crowding errors arose from both increased imprecision in target representations and substitution of flankers for targets. By contrast, VWM crowding errors arose exclusively from substitutions, which suggests that VWM transforms analog perceptual representations into discrete items. Thus, although perception and VWM share a common resolution limit, exceeding this limit reveals distinct mechanisms for perceiving images and holding them in mind. © The Author(s) 2015.

Behavior-driven arc expression is reduced in all ventral hippocampal subfields compared to CA1, CA3, and dentate gyrus in rat dorsal hippocampus.

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Chawla, M K; Sutherland, V L; Olson, K; McNaughton, B L; Barnes, C A

2018-02-01

Anatomical connectivity and lesion studies reveal distinct functional heterogeneity along the dorsal-ventral axis of the hippocampus. The immediate early gene Arc is known to be involved in neural plasticity and memory and can be used as a marker for cell activity that occurs, for example, when hippocampal place cells fire. We report here, that Arc is expressed in a greater proportion of cells in dorsal CA1, CA3, and dentate gyrus (DG), following spatial behavioral experiences compared to ventral hippocampal subregions (dorsal CA1 = 33%; ventral CA1 = 13%; dorsal CA3 = 23%; ventral CA3 = 8%; and dorsal DG = 2.5%; ventral DG = 1.2%). The technique used here to obtain estimates of numbers of behavior-driven cells across the dorsal-ventral axis, however, corresponds quite well with samples from available single unit recording studies. Several explanations for the two- to-threefold reduction in spatial behavior-driven cell activity in the ventral hippocampus can be offered. These include anatomical connectivity differences, differential gain of the self-motion signals that appear to alter the scale of place fields and the proportion of active cells, and possibly variations in the neuronal responses to non-spatial information within the hippocampus along its dorso-ventral axis. © 2017 Wiley Periodicals, Inc.

Research on a Rotating Machinery Fault Prognosis Method Using Three-Dimensional Spatial Representations

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Xiaoni Dong

2016-01-01

Full Text Available Process models and parameters are two critical steps for fault prognosis in the operation of rotating machinery. Due to the requirement for a short and rapid response, it is important to study robust sensor data representation schemes. However, the conventional holospectrum defined by one-dimensional or two-dimensional methods does not sufficiently present this information in both the frequency and time domains. To supply a complete holospectrum model, a new three-dimensional spatial representation method is proposed. This method integrates improved three-dimensional (3D holospectra and 3D filtered orbits, leading to the integration of radial and axial vibration features in one bearing section. The results from simulation and experimental analysis on a complex compressor show that the proposed method can present the real operational status and clearly reveal early faults, thus demonstrating great potential for condition-based maintenance prediction in industrial machinery.

Spatial language processing in the blind: evidence for a supramodal representation and cortical reorganization.

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Marijn E Struiksma

Full Text Available Neuropsychological and imaging studies have shown that the left supramarginal gyrus (SMG is specifically involved in processing spatial terms (e.g. above, left of, which locate places and objects in the world. The current fMRI study focused on the nature and specificity of representing spatial language in the left SMG by combining behavioral and neuronal activation data in blind and sighted individuals. Data from the blind provide an elegant way to test the supramodal representation hypothesis, i.e. abstract codes representing spatial relations yielding no activation differences between blind and sighted. Indeed, the left SMG was activated during spatial language processing in both blind and sighted individuals implying a supramodal representation of spatial and other dimensional relations which does not require visual experience to develop. However, in the absence of vision functional reorganization of the visual cortex is known to take place. An important consideration with respect to our finding is the amount of functional reorganization during language processing in our blind participants. Therefore, the participants also performed a verb generation task. We observed that only in the blind occipital areas were activated during covert language generation. Additionally, in the first task there was functional reorganization observed for processing language with a high linguistic load. As the visual cortex was not specifically active for spatial contents in the first task, and no reorganization was observed in the SMG, the latter finding further supports the notion that the left SMG is the main node for a supramodal representation of verbal spatial relations.

Daytime sleep enhances consolidation of the spatial but not motoric representation of motor sequence memory.

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Geneviève Albouy

Full Text Available Motor sequence learning is known to rely on more than a single process. As the skill develops with practice, two different representations of the sequence are formed: a goal representation built under spatial allocentric coordinates and a movement representation mediated through egocentric motor coordinates. This study aimed to explore the influence of daytime sleep (nap on consolidation of these two representations. Through the manipulation of an explicit finger sequence learning task and a transfer protocol, we show that both allocentric (spatial and egocentric (motor representations of the sequence can be isolated after initial training. Our results also demonstrate that nap favors the emergence of offline gains in performance for the allocentric, but not the egocentric representation, even after accounting for fatigue effects. Furthermore, sleep-dependent gains in performance observed for the allocentric representation are correlated with spindle density during non-rapid eye movement (NREM sleep of the post-training nap. In contrast, performance on the egocentric representation is only maintained, but not improved, regardless of the sleep/wake condition. These results suggest that motor sequence memory acquisition and consolidation involve distinct mechanisms that rely on sleep (and specifically, spindle or simple passage of time, depending respectively on whether the sequence is performed under allocentric or egocentric coordinates.

Examination about the Spatial Representation of PM2.5 Obtained from Limited Stations Using a Network Observation

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Shi, X.; Zhao, C.

2017-12-01

Haze aerosol pollution has been a focus issue in China, and its characteristics is highly demanded. With limited observation sites, aerosol properties obtained from a single site is frequently used to represent the haze condition over a large domain, such as tens of kilometers. This could result in high uncertainties in the haze characteristics due to their spatial variation. Using a network observation from November 2015 to February 2016 over an urban city in North China with high spatial resolution, this study examines the spatial representation of ground site observations. A method is first developed to determine the representative area of measurements from limited stations. The key idea of this method is to determine the spatial variability of particulate matter with diameters less than 2.5 μm (PM2.5) concentration using a variance function in 2km x 2km grids. Based on the high spatial resolution (0.5km x 0.5km) measurements of PM2.5, the grids in which PM2.5 have high correlations and weak value differences are determined as the representation area of measurements at these grids. Note that the size representation area is not exactly a circle region. It shows that the size representation are for the study region and study period ranges from 0.25 km2 to 16.25 km2. The representation area varies with locations. For the 20 km x 20 km study region, 10 station observations would have a good representation of the PM2.5 observations obtained from current 169 stations at the four-month time scale.

CaV 3.1 and CaV 3.3 account for T-type Ca2+ current in GH3 cells

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M.A. Mudado

2004-06-01

Full Text Available T-type Ca2+ channels are important for cell signaling by a variety of cells. We report here the electrophysiological and molecular characteristics of the whole-cell Ca2+ current in GH3 clonal pituitary cells. The current inactivation at 0 mV was described by a single exponential function with a time constant of 18.32 ± 1.87 ms (N = 16. The I-V relationship measured with Ca2+ as a charge carrier was shifted to the left when we applied a conditioning pre-pulse of up to -120 mV, indicating that a low voltage-activated current may be present in GH3 cells. Transient currents were first activated at -50 mV and peaked around -20 mV. The half-maximal voltage activation and the slope factors for the two conditions are -35.02 ± 2.4 and 6.7 ± 0.3 mV (pre-pulse of -120 mV, N = 15, and -27.0 ± 0.97 and 7.5 ± 0.7 mV (pre-pulse of -40 mV, N = 9. The 8-mV shift in the activation mid-point was statistically significant (P < 0.05. The tail currents decayed bi-exponentially suggesting two different T-type Ca2+ channel populations. RT-PCR revealed the presence of a1G (CaV3.1 and a1I (CaV3.3 T-type Ca2+ channel mRNA transcripts.

No functional role of attention-based rehearsal in maintenance of spatial working memory representations

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Belopolsky, A.V.; Theeuwes, J.

2009-01-01

The present study systematically examined the role of attention in maintenance of spatial representations in working memory as proposed by the attention-based rehearsal hypothesis [Awh, E., Jonides, J., & Reuter-Lorenz, P. A. (1998). Rehearsal in spatial working memory. Journal of Experimental

Exclusion of agricultural lands in spatial conservation prioritization strategies: consequences for biodiversity and ecosystem service representation.

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Durán, América P; Duffy, James P; Gaston, Kevin J

2014-10-07

Agroecosystems have traditionally been considered incompatible with biological conservation goals, and often been excluded from spatial conservation prioritization strategies. The consequences for the representativeness of identified priority areas have been little explored. Here, we evaluate these for biodiversity and carbon storage representation when agricultural land areas are excluded from a spatial prioritization strategy for South America. Comparing different prioritization approaches, we also assess how the spatial overlap of priority areas changes. The exclusion of agricultural lands was detrimental to biodiversity representation, indicating that priority areas for agricultural production overlap with areas of relatively high occurrence of species. By contrast, exclusion of agricultural lands benefits representation of carbon storage within priority areas, as lands of high value for agriculture and carbon storage overlap little. When agricultural lands were included and equally weighted with biodiversity and carbon storage, a balanced representation resulted. Our findings suggest that with appropriate management, South American agroecosystems can significantly contribute to biodiversity conservation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Learning from graphically integrated 2D and 3D representations improves retention of neuroanatomy

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Naaz, Farah

Visualizations in the form of computer-based learning environments are highly encouraged in science education, especially for teaching spatial material. Some spatial material, such as sectional neuroanatomy, is very challenging to learn. It involves learning the two dimensional (2D) representations that are sampled from the three dimensional (3D) object. In this study, a computer-based learning environment was used to explore the hypothesis that learning sectional neuroanatomy from a graphically integrated 2D and 3D representation will lead to better learning outcomes than learning from a sequential presentation. The integrated representation explicitly demonstrates the 2D-3D transformation and should lead to effective learning. This study was conducted using a computer graphical model of the human brain. There were two learning groups: Whole then Sections, and Integrated 2D3D. Both groups learned whole anatomy (3D neuroanatomy) before learning sectional anatomy (2D neuroanatomy). The Whole then Sections group then learned sectional anatomy using 2D representations only. The Integrated 2D3D group learned sectional anatomy from a graphically integrated 3D and 2D model. A set of tests for generalization of knowledge to interpreting biomedical images was conducted immediately after learning was completed. The order of presentation of the tests of generalization of knowledge was counterbalanced across participants to explore a secondary hypothesis of the study: preparation for future learning. If the computer-based instruction programs used in this study are effective tools for teaching anatomy, the participants should continue learning neuroanatomy with exposure to new representations. A test of long-term retention of sectional anatomy was conducted 4-8 weeks after learning was completed. The Integrated 2D3D group was better than the Whole then Sections group in retaining knowledge of difficult instances of sectional anatomy after the retention interval. The benefit

Deployment of spatial attention towards locations in memory representations. An EEG study.

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Leszczyński, Marcin; Wykowska, Agnieszka; Perez-Osorio, Jairo; Müller, Hermann J

2013-01-01

Recalling information from visual short-term memory (VSTM) involves the same neural mechanisms as attending to an actually perceived scene. In particular, retrieval from VSTM has been associated with orienting of visual attention towards a location within a spatially-organized memory representation. However, an open question concerns whether spatial attention is also recruited during VSTM retrieval even when performing the task does not require access to spatial coordinates of items in the memorized scene. The present study combined a visual search task with a modified, delayed central probe protocol, together with EEG analysis, to answer this question. We found a temporal contralateral negativity (TCN) elicited by a centrally presented go-signal which was spatially uninformative and featurally unrelated to the search target and informed participants only about a response key that they had to press to indicate a prepared target-present vs. -absent decision. This lateralization during VSTM retrieval (TCN) provides strong evidence of a shift of attention towards the target location in the memory representation, which occurred despite the fact that the present task required no spatial (or featural) information from the search to be encoded, maintained, and retrieved to produce the correct response and that the go-signal did not itself specify any information relating to the location and defining feature of the target.

Deployment of spatial attention towards locations in memory representations. An EEG study.

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Marcin Leszczyński

Full Text Available Recalling information from visual short-term memory (VSTM involves the same neural mechanisms as attending to an actually perceived scene. In particular, retrieval from VSTM has been associated with orienting of visual attention towards a location within a spatially-organized memory representation. However, an open question concerns whether spatial attention is also recruited during VSTM retrieval even when performing the task does not require access to spatial coordinates of items in the memorized scene. The present study combined a visual search task with a modified, delayed central probe protocol, together with EEG analysis, to answer this question. We found a temporal contralateral negativity (TCN elicited by a centrally presented go-signal which was spatially uninformative and featurally unrelated to the search target and informed participants only about a response key that they had to press to indicate a prepared target-present vs. -absent decision. This lateralization during VSTM retrieval (TCN provides strong evidence of a shift of attention towards the target location in the memory representation, which occurred despite the fact that the present task required no spatial (or featural information from the search to be encoded, maintained, and retrieved to produce the correct response and that the go-signal did not itself specify any information relating to the location and defining feature of the target.

How Fast Do Objects Fall in Visual Memory? Uncovering the Temporal and Spatial Features of Representational Gravity.

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De Sá Teixeira, Nuno

2016-01-01

Visual memory for the spatial location where a moving target vanishes has been found to be systematically displaced downward in the direction of gravity. Moreover, it was recently reported that the magnitude of the downward error increases steadily with increasing retention intervals imposed after object's offset and before observers are allowed to perform the spatial localization task, in a pattern where the remembered vanishing location drifts downward as if following a falling trajectory. This outcome was taken to reflect the dynamics of a representational model of earth's gravity. The present study aims to establish the spatial and temporal features of this downward drift by taking into account the dynamics of the motor response. The obtained results show that the memory for the last location of the target drifts downward with time, thus replicating previous results. Moreover, the time taken for completion of the behavioural localization movements seems to add to the imposed retention intervals in determining the temporal frame during which the visual memory is updated. Overall, it is reported that the representation of spatial location drifts downward by about 3 pixels for each two-fold increase of time until response. The outcomes are discussed in relation to a predictive internal model of gravity which outputs an on-line spatial update of remembered objects' location.

Entorhinal-CA3 Dual-Input Control of Spike Timing in the Hippocampus by Theta-Gamma Coupling.

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Fernández-Ruiz, Antonio; Oliva, Azahara; Nagy, Gergő A; Maurer, Andrew P; Berényi, Antal; Buzsáki, György

2017-03-08

Theta-gamma phase coupling and spike timing within theta oscillations are prominent features of the hippocampus and are often related to navigation and memory. However, the mechanisms that give rise to these relationships are not well understood. Using high spatial resolution electrophysiology, we investigated the influence of CA3 and entorhinal inputs on the timing of CA1 neurons. The theta-phase preference and excitatory strength of the afferent CA3 and entorhinal inputs effectively timed the principal neuron activity, as well as regulated distinct CA1 interneuron populations in multiple tasks and behavioral states. Feedback potentiation of distal dendritic inhibition by CA1 place cells attenuated the excitatory entorhinal input at place field entry, coupled with feedback depression of proximal dendritic and perisomatic inhibition, allowing the CA3 input to gain control toward the exit. Thus, upstream inputs interact with local mechanisms to determine theta-phase timing of hippocampal neurons to support memory and spatial navigation. Copyright © 2017 Elsevier Inc. All rights reserved.

Spatially selective Er/Yb-doped CaF2 crystal formation by CO2 laser exposure

International Nuclear Information System (INIS)

Kim, Dong-Seon; Lee, Jin-Ho; Lim, Ki-Soo

2014-01-01

Highlights: • Oxyfluoride glass–ceramics containing CaF 2 nanocrystals doped with Er 3+ and Yb 3+ ions were formed on the glass surface by CO 2 laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF 2 nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO 2 laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF 2 and miner Ca 2 SiO 4 nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment

Spatially selective Er/Yb-doped CaF2 crystal formation by CO2 laser exposure

International Nuclear Information System (INIS)

Kim, Dong-Seon; Lee, Jin-Ho; Lim, Ki-Soo

2015-01-01

Highlights: • Oxyfluoride glass–ceramics containing CaF 2 nanocrystals doped with Er 3+ and Yb 3+ ions were formed on the glass surface by CO 2 laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF 2 nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO 2 laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF 2 and miner Ca 2 SiO 4 nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment

Reactivation of Rate Remapping in CA3.

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Schwindel, C Daniela; Navratilova, Zaneta; Ali, Karim; Tatsuno, Masami; McNaughton, Bruce L

2016-09-07

The hippocampus is thought to contribute to episodic memory by creating, storing, and reactivating patterns that are unique to each experience, including different experiences that happen at the same location. Hippocampus can combine spatial and contextual/episodic information using a dual coding scheme known as "global" and "rate" remapping. Global remapping selects which set of neurons can activate at a given location. Rate remapping readjusts the firing rates of this set depending on current experience, thus expressing experience-unique patterns at each location. But can the experience-unique component be retrieved spontaneously? Whereas reactivation of recent, spatially selective patterns in hippocampus is well established, it is never perfect, raising the issue of whether the experiential component might be absent. This question is key to the hypothesis that hippocampus can assist memory consolidation by reactivating and broadcasting experience-specific "index codes" to neocortex. In CA3, global remapping exhibits attractor-like dynamics, whereas rate remapping apparently does not, leading to the hypothesis that only the former can be retrieved associatively and casting doubt on the general consolidation hypothesis. Therefore, we studied whether the rate component is reactivated spontaneously during sleep. We conducted neural ensemble recordings from CA3 while rats ran on a circular track in different directions (in different sessions) and while they slept. It was shown previously that the two directions of running result in strong rate remapping. During sleep, the most recent rate distribution was reactivated preferentially. Therefore, CA3 can retrieve patterns spontaneously that are unique to both the location and the content of recent experience. The hippocampus is required for memory of events and their spatial contexts. The primary correlate of hippocampal activity is location in space, but multiple memories can occur in the same location. To be useful

Gender differences in the use of external landmarks versus spatial representations updated by self-motion.

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Lambrey, Simon; Berthoz, Alain

2007-09-01

Numerous data in the literature provide evidence for gender differences in spatial orientation. In particular, it has been suggested that spatial representations of large-scale environments are more accurate in terms of metric information in men than in women but are richer in landmark information in women than in men. One explanatory hypothesis is that men and women differ in terms of navigational processes they used in daily life. The present study investigated this hypothesis by distinguishing two navigational processes: spatial updating by self-motion and landmark-based orientation. Subjects were asked to perform a pointing task in three experimental conditions, which differed in terms of reliability of the external landmarks that could be used. Two groups of subjects were distinguished, a mobile group and an immobile group, in which spatial updating of environmental locations did not have the same degree of importance for the correct performance of the pointing task. We found that men readily relied on an internal egocentric representation of where landmarks were expected to be in order to perform the pointing task, a representation that could be updated during self-motion (spatial updating). In contrast, women seemed to take their bearings more readily on the basis of the stable landmarks of the external world. We suggest that this gender difference in spatial orientation is not due to differences in information processing abilities but rather due to the differences in higher level strategies.

DNA methylation regulates neurophysiological spatial representation in memory formation

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Eric D. Roth

2015-04-01

Full Text Available Epigenetic mechanisms including altered DNA methylation are critical for altered gene transcription subserving synaptic plasticity and the retention of learned behavior. Here, we tested the idea that one role for activity-dependent altered DNA methylation is stabilization of cognition-associated hippocampal place cell firing in response to novel place learning. We observed that a behavioral protocol (spatial exploration of a novel environment known to induce hippocampal place cell remapping resulted in alterations of hippocampal Bdnf DNA methylation. Further studies using neurophysiological in vivo single-unit recordings revealed that pharmacological manipulations of DNA methylation decreased long-term but not short-term place field stability. Together, our data highlight a role for DNA methylation in regulating neurophysiological spatial representation and memory formation.

DNA methylation regulates neurophysiological spatial representation in memory formation.

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Roth, Eric D; Roth, Tania L; Money, Kelli M; SenGupta, Sonda; Eason, Dawn E; Sweatt, J David

2015-04-01

Epigenetic mechanisms including altered DNA methylation are critical for altered gene transcription subserving synaptic plasticity and the retention of learned behavior. Here we tested the idea that one role for activity-dependent altered DNA methylation is stabilization of cognition-associated hippocampal place cell firing in response to novel place learning. We observed that a behavioral protocol (spatial exploration of a novel environment) known to induce hippocampal place cell remapping resulted in alterations of hippocampal Bdnf DNA methylation. Further studies using neurophysiological in vivo single unit recordings revealed that pharmacological manipulations of DNA methylation decreased long-term but not short-term place field stability. Together our data highlight a role for DNA methylation in regulating neurophysiological spatial representation and memory formation.

Evidence for cue-independent spatial representation in the human auditory cortex during active listening.

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Higgins, Nathan C; McLaughlin, Susan A; Rinne, Teemu; Stecker, G Christopher

2017-09-05

Few auditory functions are as important or as universal as the capacity for auditory spatial awareness (e.g., sound localization). That ability relies on sensitivity to acoustical cues-particularly interaural time and level differences (ITD and ILD)-that correlate with sound-source locations. Under nonspatial listening conditions, cortical sensitivity to ITD and ILD takes the form of broad contralaterally dominated response functions. It is unknown, however, whether that sensitivity reflects representations of the specific physical cues or a higher-order representation of auditory space (i.e., integrated cue processing), nor is it known whether responses to spatial cues are modulated by active spatial listening. To investigate, sensitivity to parametrically varied ITD or ILD cues was measured using fMRI during spatial and nonspatial listening tasks. Task type varied across blocks where targets were presented in one of three dimensions: auditory location, pitch, or visual brightness. Task effects were localized primarily to lateral posterior superior temporal gyrus (pSTG) and modulated binaural-cue response functions differently in the two hemispheres. Active spatial listening (location tasks) enhanced both contralateral and ipsilateral responses in the right hemisphere but maintained or enhanced contralateral dominance in the left hemisphere. Two observations suggest integrated processing of ITD and ILD. First, overlapping regions in medial pSTG exhibited significant sensitivity to both cues. Second, successful classification of multivoxel patterns was observed for both cue types and-critically-for cross-cue classification. Together, these results suggest a higher-order representation of auditory space in the human auditory cortex that at least partly integrates the specific underlying cues.

Dendritic Kv3.3 potassium channels in cerebellar purkinje cells regulate generation and spatial dynamics of dendritic Ca2+ spikes.

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Zagha, Edward; Manita, Satoshi; Ross, William N; Rudy, Bernardo

2010-06-01

Purkinje cell dendrites are excitable structures with intrinsic and synaptic conductances contributing to the generation and propagation of electrical activity. Voltage-gated potassium channel subunit Kv3.3 is expressed in the distal dendrites of Purkinje cells. However, the functional relevance of this dendritic distribution is not understood. Moreover, mutations in Kv3.3 cause movement disorders in mice and cerebellar atrophy and ataxia in humans, emphasizing the importance of understanding the role of these channels. In this study, we explore functional implications of this dendritic channel expression and compare Purkinje cell dendritic excitability in wild-type and Kv3.3 knockout mice. We demonstrate enhanced excitability of Purkinje cell dendrites in Kv3.3 knockout mice, despite normal resting membrane properties. Combined data from local application pharmacology, voltage clamp analysis of ionic currents, and assessment of dendritic Ca(2+) spike threshold in Purkinje cells suggest a role for Kv3.3 channels in opposing Ca(2+) spike initiation. To study the physiological relevance of altered dendritic excitability, we measured [Ca(2+)](i) changes throughout the dendritic tree in response to climbing fiber activation. Ca(2+) signals were specifically enhanced in distal dendrites of Kv3.3 knockout Purkinje cells, suggesting a role for dendritic Kv3.3 channels in regulating propagation of electrical activity and Ca(2+) influx in distal dendrites. These findings characterize unique roles of Kv3.3 channels in dendrites, with implications for synaptic integration, plasticity, and human disease.

Recurrent synapses and circuits in the CA3 region of the hippocampus: an associative network.

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Richard eMiles

2014-01-01

Full Text Available In the CA3 region of the hippocampus, pyramidal cells excite other pyramidal cells and interneurons. The axons of CA3 pyramidal cells spread throughout most of the region to form an associative network. These connections were first drawn by Cajal and Lorente de No. Their physiological properties were explored to understand epileptiform discharges generated in the region. Synapses between pairs of pyramidal cells involve one or few release sites and are weaker than connections made by mossy fibres on CA3 pyramidal cells. Synapses with interneurons are rather effective, as needed to control unchecked excitation. We examine contributions of recurrent synapses to epileptiform synchrony, to the genesis of sharp waves in the CA3 region and to population oscillations at theta and gamma frequencies. Recurrent connections in CA3, as other associative cortices, have a lower connectivity spread over a larger area than in primary sensory cortices. This sparse, but wide-ranging connectivity serves the functions of an associative network, including acquisition of neuronal representations as activity in groups of CA3 cells and completion involving the recall from partial cues of these ensemble firing patterns.

Synaptically evoked Ca2+ release from intracellular stores is not influenced by vesicular zinc in CA3 hippocampal pyramidal neurones.

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Evstratova, Alesya; Tóth, Katalin

2011-12-01

The co-release of neuromodulatory substances in combination with classic neurotransmitters such as glutamate and GABA from individual presynaptic nerve terminals has the capacity to dramatically influence synaptic efficacy and plasticity. At hippocampal mossy fibre synapses vesicular zinc is suggested to serve as a cotransmitter capable of regulating calcium release from internal stores in postsynaptic CA3 pyramidal cells. Here we investigated this possibility using combined intracellular ratiometric calcium imaging and patch-clamp recording techniques. In acute hippocampal slices a brief train of mossy fibre stimulation produced a large, delayed postsynaptic Ca(2+) wave that was spatially restricted to the proximal apical dendrites of CA3 pyramidal cells within stratum lucidum. This calcium increase was sensitive to intracellularly applied heparin indicating reliance upon release from internal stores and was triggered by activation of both group I metabotropic glutamate and NMDA receptors. Importantly, treatment of slices with the membrane-impermeant zinc chelator CaEDTA did not influence the synaptically evoked postsynaptic Ca(2+) waves. Moreover, mossy fibre stimulus evoked postsynaptic Ca(2+) signals were not significantly different between wild-type and zinc transporter 3 (ZnT3) knock-out animals. Considered together our data do not support a role for vesicular zinc in regulating mossy fibre evoked Ca(2+) release from CA3 pyramidal cell internal stores.

Unbounding the mental number line – New evidence on children’s spatial representation of numbers

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Tanja eLink

2014-01-01

Full Text Available Number line estimation (i.e., indicating the position of a given number on a physical line is a standard assessment of children’s spatial representation of number magnitude. Importantly, there is an ongoing debate on the question in how far the bounded task version with start and endpoint given (e.g., 0 and 100 might induce specific estimation strategies and thus may not allow for unbiased inferences on the underlying representation. Recently, a new unbounded version of the task was suggested with only the start point and a unit fixed (e.g., the distance from 0 to 1. In adults this task provided a less biased index of the spatial representation of number magnitude. Yet, so far there are no children data available for the unbounded number line estimation task. Therefore, we conducted a cross-sectional study on primary school children performing both, the bounded and the unbounded version of the task. We observed clear evidence for systematic strategic influences (i.e., the consideration of reference points in the bounded number line estimation task for children older than grade two whereas there were no such indications for the unbounded version for any one of the age groups. In summary, the current data corroborate the unbounded number line estimation task to be a valuable tool for assessing children's spatial representation of number magnitude in a systematic and unbiased manner. Yet, similar results for the bounded and the unbounded version of the task for first- and second-graders may indicate that both versions of the task might assess the same underlying representation for relatively younger children - at least in number ranges familiar to the children assessed. This is of particular importance for inferences about the nature and development of children's magnitude representation.

Where to attend next: guiding refreshing of visual, spatial, and verbal representations in working memory.

Science.gov (United States)

Souza, Alessandra S; Vergauwe, Evie; Oberauer, Klaus

2018-04-23

One of the functions that attention may serve in working memory (WM) is boosting information accessibility, a mechanism known as attentional refreshing. Refreshing is assumed to be a domain-general process operating on visual, spatial, and verbal representations alike. So far, few studies have directly manipulated refreshing of individual WM representations to measure the WM benefits of refreshing. Recently, a guided-refreshing method was developed, which consists of presenting cues during the retention interval of a WM task to instruct people to refresh (i.e., attend to) the cued items. Using a continuous-color reconstruction task, previous studies demonstrated that the error in reporting a color varies linearly with the frequency with which it was refreshed. Here, we extend this approach to assess the WM benefits of refreshing different representation types, from colors to spatial locations and words. Across six experiments, we show that refreshing frequency modulates performance in all stimulus domains in accordance with the tenet that refreshing is a domain-general process in WM. The benefits of refreshing were, however, larger for visual-spatial than verbal materials. © 2018 New York Academy of Sciences.

Thermoluminescence of CaCO3:Dy and CaCO3:Mn

International Nuclear Information System (INIS)

Bapat, V.N.; Nambi, K.S.V.

1976-01-01

CaCO 3 samples doped with Dy and Mn were prepared in the laboratory by co-precipitation techniques. Thermoluminescence and emission spectra of these phosphors were studied and were compared with those of the naturally occuring calcite and undoped CaCO 3 samples. Dy-doping seems to give a more efficient phosphor and indicates a possibility of getting a better phosphor by a judicious choice of a rare earth doping of CaCO 3 . Interesting result have been obtained on the TL glow curve variations of these phosphors with different temperature treatments prior to irradiation. (author)

Evolution and sign control of square-wave-like anisotropic magneto-resistance in spatially confined La{sub 0.3}Pr{sub 0.4}Ca{sub 0.3}MnO{sub 3}/LaAlO{sub 3}(001) manganite thin films

Energy Technology Data Exchange (ETDEWEB)

Alagoz, H. S., E-mail: alagoz@ualberta.ca; Jeon, J.; Keating, S.; Chow, K. H., E-mail: khchow@ualberta.ca; Jung, J., E-mail: jjung@ualberta.ca [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)

2016-04-14

We investigated magneto-transport properties of a compressively strained spatially confined La{sub 0.3}Pr{sub 0.4}Ca{sub 0.3}MnO{sub 3} (LPCMO) thin film micro-bridge deposited on LaAlO{sub 3}. Angular dependence of the magneto-resistance R(θ) of this bridge, where θ is the angle between the magnetic field and the current directions in the film plane, exhibits sharp positive and negative percolation jumps near T{sub MIT}. The sign and the magnitude of these jumps can be tuned using the magnetic field. Such behavior has not been observed in LPCMO micro-bridges subjected to tensile strain, indicating a correlation between the type of the lattice strain, the distribution of electronic domains, and the anisotropic magneto-resistance in spatially confined manganite systems.

Electrolytic lesions of dorsal CA3 impair episodic-like memory in rats.

Science.gov (United States)

Li, Jay-Shake; Chao, Yuen-Shin

2008-02-01

Episodic memory is the ability to recollect one's past experiences occurring in an unique spatial and temporal context. In non-human animals, it is expressed in the ability to combine "what", "where" and "when" factors to form an integrated memory system. During the search for its neural substrates, the hippocampus has attracted a lot of attentions. Yet, it is not yet possible to induce a pure episodic-like memory deficit in animal studies without being confounded by impairments in the spatial cognition. Here, we present a lesion study evidencing direct links between the hippocampus CA3 region and the episodic-like memory in rats. In a spontaneous object exploration task, lesioned rats showed no interaction between the temporal and spatial elements in their memory associated with the objects. In separate tests carried out subsequently, the same animals still expressed abilities to process spatial, temporal, and object recognition memory. In conclusions, our results support the idea that the hippocampus CA3 has a particular status in the neural mechanism of the episodic-like memory system. It is responsible for combining information from different modules of cognitive processes.

Disruption of hippocampal CA3 network: effects on episodic-like memory processing in C57BL/6J mice.

Science.gov (United States)

Daumas, Stéphanie; Halley, Hélène; Lassalle, Jean-Michel

2004-07-01

Lesion studies have demonstrated the prominent role of the hippocampus in spatial and contextual learning. To better understand how contextual information is processed in the CA3 region during learning, we focused on the CA3 autoassociative network hypothesis. We took advantage of a particularity of the mossy fibre (MF) synapses, i.e. their high zinc concentration, to reversibly disrupt the afferent MF pathway by microinfusions of an intracellular (DEDTC) or an extracellular (CaEDTA) zinc chelator into the CA3 area of the dorsal hippocampus of mice. Disruption of the CA3 network significantly impaired the acquisition and the consolidation of contextual fear conditioning, whereas contextual retrieval was unaffected. These results also suggest a heterogeneity between the cognitive processes underlying spatial and contextual memory that might be linked to the specific involvement of free zinc in contextual information processing.

Separating the Representation from the Science: Training Students in Comprehending 3D Diagrams

Science.gov (United States)

Bemis, K. G.; Silver, D.; Chiang, J.; Halpern, D.; Oh, K.; Tremaine, M.

2011-12-01

Studies of students taking first year geology and earth science courses at universities find that a remarkable number of them are confused by the three-dimensional representations used to explain the science [1]. Comprehension of these 3D representations has been found to be related to an individual's spatial ability [2]. A variety of interactive programs and animations have been created to help explain the diagrams to beginning students [3, 4]. This work has demonstrated comprehension improvement and removed a gender gap between male (high spatial) and female (low spatial) students [5]. However, not much research has examined what makes the 3D diagrams so hard to understand or attempted to build a theory for creating training designed to remove these difficulties. Our work has separated the science labeling and comprehension of the diagrams from the visualizations to examine how individuals mentally see the visualizations alone. In particular, we asked subjects to create a cross-sectional drawing of the internal structure of various 3D diagrams. We found that viewing planes (the coordinate system the designer applies to the diagram), cutting planes (the planes formed by the requested cross sections) and visual property planes (the planes formed by the prominent features of the diagram, e.g., a layer at an angle of 30 degrees to the top surface of the diagram) that deviated from a Cartesian coordinate system imposed by the viewer caused significant problems for subjects, in part because these deviations forced them to mentally re-orient their viewing perspective. Problems with deviations in all three types of plane were significantly harder than those deviating on one or two planes. Our results suggest training that does not focus on showing how the components of various 3D geologic formations are put together but rather training that guides students in re-orienting themselves to deviations that differ from their right-angle view of the world, e.g., by showing how

Key features of human episodic recollection in the cross-episode retrieval of rat hippocampus representations of space.

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Eduard Kelemen

2013-07-01

Full Text Available Neurophysiological studies focus on memory retrieval as a reproduction of what was experienced and have established that neural discharge is replayed to express memory. However, cognitive psychology has established that recollection is not a verbatim replay of stored information. Recollection is constructive, the product of memory retrieval cues, the information stored in memory, and the subject's state of mind. We discovered key features of constructive recollection embedded in the rat CA1 ensemble discharge during an active avoidance task. Rats learned two task variants, one with the arena stable, the other with it rotating; each variant defined a distinct behavioral episode. During the rotating episode, the ensemble discharge of CA1 principal neurons was dynamically organized to concurrently represent space in two distinct codes. The code for spatial reference frame switched rapidly between representing the rat's current location in either the stationary spatial frame of the room or the rotating frame of the arena. The code for task variant switched less frequently between a representation of the current rotating episode and the stable episode from the rat's past. The characteristics and interplay of these two hippocampal codes revealed three key properties of constructive recollection. (1 Although the ensemble representations of the stable and rotating episodes were distinct, ensemble discharge during rotation occasionally resembled the stable condition, demonstrating cross-episode retrieval of the representation of the remote, stable episode. (2 This cross-episode retrieval at the level of the code for task variant was more likely when the rotating arena was about to match its orientation in the stable episode. (3 The likelihood of cross-episode retrieval was influenced by preretrieval information that was signaled at the level of the code for spatial reference frame. Thus key features of episodic recollection manifest in rat hippocampal

Relative contributions of visual and auditory spatial representations to tactile localization.

Science.gov (United States)

Noel, Jean-Paul; Wallace, Mark

2016-02-01

Spatial localization of touch is critically dependent upon coordinate transformation between different reference frames, which must ultimately allow for alignment between somatotopic and external representations of space. Although prior work has shown an important role for cues such as body posture in influencing the spatial localization of touch, the relative contributions of the different sensory systems to this process are unknown. In the current study, we had participants perform a tactile temporal order judgment (TOJ) under different body postures and conditions of sensory deprivation. Specifically, participants performed non-speeded judgments about the order of two tactile stimuli presented in rapid succession on their ankles during conditions in which their legs were either uncrossed or crossed (and thus bringing somatotopic and external reference frames into conflict). These judgments were made in the absence of 1) visual, 2) auditory, or 3) combined audio-visual spatial information by blindfolding and/or placing participants in an anechoic chamber. As expected, results revealed that tactile temporal acuity was poorer under crossed than uncrossed leg postures. Intriguingly, results also revealed that auditory and audio-visual deprivation exacerbated the difference in tactile temporal acuity between uncrossed to crossed leg postures, an effect not seen for visual-only deprivation. Furthermore, the effects under combined audio-visual deprivation were greater than those seen for auditory deprivation. Collectively, these results indicate that mechanisms governing the alignment between somatotopic and external reference frames extend beyond those imposed by body posture to include spatial features conveyed by the auditory and visual modalities - with a heavier weighting of auditory than visual spatial information. Thus, sensory modalities conveying exteroceptive spatial information contribute to judgments regarding the localization of touch. Copyright © 2016

Analogical processes in children's understanding of spatial representations.

Science.gov (United States)

Yuan, Lei; Uttal, David; Gentner, Dedre

2017-06-01

We propose that map reading can be construed as a form of analogical mapping. We tested 2 predictions that follow from this claim: First, young children's patterns of performance in map reading tasks should parallel those found in analogical mapping tasks; and, second, children will benefit from guided alignment instructions that help them see the relational correspondences between the map and the space. In 4 experiments, 3-year-olds completed a map reading task in which they were asked to find hidden objects in a miniature room, using a corresponding map. We manipulated the availability of guided alignment (showing children the analogical mapping between maps and spaces; Experiments 1, 2, and 3a), the format of guided alignment (gesture or relational language; Experiment 2), and the iconicity of maps (Experiments 3a and 3b). We found that (a) young children's difficulties in map reading follow from known patterns of analogical development-for example, focusing on object similarity over relational similarity; and (b) guided alignment based on analogical reasoning led to substantially better performance. Results also indicated that children's map reading performance was affected by the format of guided alignment, the iconicity of the maps, and the order of tasks. The results bear on the developmental mechanisms underlying young children's learning of spatial representations and also suggest ways to support this learning. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Spatially selective Er/Yb-doped CaF{sub 2} crystal formation by CO{sub 2} laser exposure

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Seon; Lee, Jin-Ho; Lim, Ki-Soo, E-mail: kslim@chungbuk.ac.kr

2014-10-30

Highlights: • Oxyfluoride glass–ceramics containing CaF{sub 2} nanocrystals doped with Er{sup 3+} and Yb{sup 3+} ions were formed on the glass surface by CO{sub 2} laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF{sub 2} nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO{sub 2} laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF{sub 2} and miner Ca{sub 2}SiO{sub 4} nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment.

Spatially selective Er/Yb-doped CaF{sub 2} crystal formation by CO{sub 2} laser exposure

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Seon; Lee, Jin-Ho; Lim, Ki-Soo, E-mail: kslim@chungbuk.ac.kr

2015-04-15

Highlights: • Oxyfluoride glass–ceramics containing CaF{sub 2} nanocrystals doped with Er{sup 3+} and Yb{sup 3+} ions were formed on the glass surface by CO{sub 2} laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF{sub 2} nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO{sub 2} laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF{sub 2} and miner Ca{sub 2}SiO{sub 4} nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment.

Diminished Dentate Gyrus Filtering of Cortical Input Leads to Enhanced Area Ca3 Excitability after Mild Traumatic Brain Injury.

Science.gov (United States)

Folweiler, Kaitlin A; Samuel, Sandy; Metheny, Hannah E; Cohen, Akiva S

2018-04-06

Mild traumatic brain injury (mTBI) disrupts hippocampal function and can lead to long-lasting episodic memory impairments. The encoding of episodic memories relies on spatial information processing within the hippocampus. As the primary entry point for spatial information into the hippocampus, the dentate gyrus is thought to function as a physiological gate, or filter, of afferent excitation before reaching downstream area Cornu Ammonis (CA3). Although injury has previously been shown to alter dentate gyrus network excitability, it is unknown whether mTBI affects dentate gyrus output to area CA3. In this study, we assessed hippocampal function, specifically the interaction between the dentate gyrus and CA3, using behavioral and electrophysiological techniques in ex vivo brain slices 1 week following mild lateral fluid percussion injury (LFPI). Behaviorally, LFPI mice were found to be impaired in an object-place recognition task, indicating that spatial information processing in the hippocampus is disrupted. Extracellular recordings and voltage-sensitive dye imaging demonstrated that perforant path activation leads to the aberrant spread of excitation from the dentate gyrus into area CA3 along the mossy fiber pathway. These results suggest that after mTBI, the dentate gyrus has a diminished capacity to regulate cortical input into the hippocampus, leading to increased CA3 network excitability. The loss of the dentate filtering efficacy reveals a potential mechanism by which hippocampal-dependent spatial information processing is disrupted, and may contribute to memory dysfunction after mTBI.

Improving the spatial representation of basin hydrology and flow processes in the SWAT model

OpenAIRE

Rathjens, Hendrik

2014-01-01

This dissertation aims at improving the spatial representation of basin hydrology and flow processes in the SWAT model. Die vorliegende Dissertation stellt die methodischen Grundlage zur räumlich differenzierten Modellierung mit dem Modell SWAT dar.

Hyperspectral Image Classification Based on the Combination of Spatial-spectral Feature and Sparse Representation

Directory of Open Access Journals (Sweden)

YANG Zhaoxia

2015-07-01

Full Text Available In order to avoid the problem of being over-dependent on high-dimensional spectral feature in the traditional hyperspectral image classification, a novel approach based on the combination of spatial-spectral feature and sparse representation is proposed in this paper. Firstly, we extract the spatial-spectral feature by reorganizing the local image patch with the first d principal components(PCs into a vector representation, followed by a sorting scheme to make the vector invariant to local image rotation. Secondly, we learn the dictionary through a supervised method, and use it to code the features from test samples afterwards. Finally, we embed the resulting sparse feature coding into the support vector machine(SVM for hyperspectral image classification. Experiments using three hyperspectral data show that the proposed method can effectively improve the classification accuracy comparing with traditional classification methods.

Spatially-explicit estimation of geographical representation in large-scale species distribution datasets.

Science.gov (United States)

Kalwij, Jesse M; Robertson, Mark P; Ronk, Argo; Zobel, Martin; Pärtel, Meelis

2014-01-01

Much ecological research relies on existing multispecies distribution datasets. Such datasets, however, can vary considerably in quality, extent, resolution or taxonomic coverage. We provide a framework for a spatially-explicit evaluation of geographical representation within large-scale species distribution datasets, using the comparison of an occurrence atlas with a range atlas dataset as a working example. Specifically, we compared occurrence maps for 3773 taxa from the widely-used Atlas Florae Europaeae (AFE) with digitised range maps for 2049 taxa of the lesser-known Atlas of North European Vascular Plants. We calculated the level of agreement at a 50-km spatial resolution using average latitudinal and longitudinal species range, and area of occupancy. Agreement in species distribution was calculated and mapped using Jaccard similarity index and a reduced major axis (RMA) regression analysis of species richness between the entire atlases (5221 taxa in total) and between co-occurring species (601 taxa). We found no difference in distribution ranges or in the area of occupancy frequency distribution, indicating that atlases were sufficiently overlapping for a valid comparison. The similarity index map showed high levels of agreement for central, western, and northern Europe. The RMA regression confirmed that geographical representation of AFE was low in areas with a sparse data recording history (e.g., Russia, Belarus and the Ukraine). For co-occurring species in south-eastern Europe, however, the Atlas of North European Vascular Plants showed remarkably higher richness estimations. Geographical representation of atlas data can be much more heterogeneous than often assumed. Level of agreement between datasets can be used to evaluate geographical representation within datasets. Merging atlases into a single dataset is worthwhile in spite of methodological differences, and helps to fill gaps in our knowledge of species distribution ranges. Species distribution

Providing a non-deterministic representation of spatial variability of precipitation in the Everest region

Directory of Open Access Journals (Sweden)

J. Eeckman

2017-09-01

Full Text Available This paper provides a new representation of the effect of altitude on precipitation that represents spatial and temporal variability in precipitation in the Everest region. Exclusive observation data are used to infer a piecewise linear function for the relation between altitude and precipitation and significant seasonal variations are highlighted. An original ensemble approach is applied to provide non-deterministic water budgets for middle and high-mountain catchments. Physical processes at the soil–atmosphere interface are represented through the Interactions Soil–Biosphere–Atmosphere (ISBA surface scheme. Uncertainties associated with the model parametrization are limited by the integration of in situ measurements of soils and vegetation properties. Uncertainties associated with the representation of the orographic effect are shown to account for up to 16 % of annual total precipitation. Annual evapotranspiration is shown to represent 26 % ± 1 % of annual total precipitation for the mid-altitude catchment and 34% ± 3 % for the high-altitude catchment. Snowfall contribution is shown to be neglectable for the mid-altitude catchment, and it represents up to 44 % ± 8 % of total precipitation for the high-altitude catchment. These simulations on the local scale enhance current knowledge of the spatial variability in hydroclimatic processes in high- and mid-altitude mountain environments.

Attention-spreading based on hierarchical spatial representations for connected objects.

Science.gov (United States)

Kasai, Tetsuko

2010-01-01

Attention selects objects or groups as the most fundamental unit, and this may be achieved through a process in which attention automatically spreads throughout their entire region. Previously, we found that a lateralized potential relative to an attended hemifield at occipito-temporal electrode sites reflects attention-spreading in response to connected bilateral stimuli [Kasai, T., & Kondo, M. Electrophysiological correlates of attention-spreading in visual grouping. NeuroReport, 18, 93-98, 2007]. The present study examined the nature of object representations by manipulating the extent of grouping through connectedness, while controlling the symmetrical structure of bilateral stimuli. The electrophysiological results of two experiments consistently indicated that attention was guided twice in association with perceptual grouping in the early phase (N1, 150-200 msec poststimulus) and with the unity of an object in the later phase (N2pc, 310/330-390 msec). This suggests that there are two processes in object-based spatial selection, and these are discussed with regard to their cognitive mechanisms and object representations.

Experience-Dependency of Reliance on Local Visual and Idiothetic Cues for Spatial Representations Created in the Absence of Distal Information

Directory of Open Access Journals (Sweden)

Fabian Draht

2017-06-01

Full Text Available Spatial encoding in the hippocampus is based on a range of different input sources. To generate spatial representations, reliable sensory cues from the external environment are integrated with idiothetic cues, derived from self-movement, that enable path integration and directional perception. In this study, we examined to what extent idiothetic cues significantly contribute to spatial representations and navigation: we recorded place cells while rodents navigated towards two visually identical chambers in 180° orientation via two different paths in darkness and in the absence of reliable auditory or olfactory cues. Our goal was to generate a conflict between local visual and direction-specific information, and then to assess which strategy was prioritized in different learning phases. We observed that, in the absence of distal cues, place fields are initially controlled by local visual cues that override idiothetic cues, but that with multiple exposures to the paradigm, spaced at intervals of days, idiothetic cues become increasingly implemented in generating an accurate spatial representation. Taken together, these data support that, in the absence of distal cues, local visual cues are prioritized in the generation of context-specific spatial representations through place cells, whereby idiothetic cues are deemed unreliable. With cumulative exposures to the environments, the animal learns to attend to subtle idiothetic cues to resolve the conflict between visual and direction-specific information.

Experience-Dependency of Reliance on Local Visual and Idiothetic Cues for Spatial Representations Created in the Absence of Distal Information.

Science.gov (United States)

Draht, Fabian; Zhang, Sijie; Rayan, Abdelrahman; Schönfeld, Fabian; Wiskott, Laurenz; Manahan-Vaughan, Denise

2017-01-01

Spatial encoding in the hippocampus is based on a range of different input sources. To generate spatial representations, reliable sensory cues from the external environment are integrated with idiothetic cues, derived from self-movement, that enable path integration and directional perception. In this study, we examined to what extent idiothetic cues significantly contribute to spatial representations and navigation: we recorded place cells while rodents navigated towards two visually identical chambers in 180° orientation via two different paths in darkness and in the absence of reliable auditory or olfactory cues. Our goal was to generate a conflict between local visual and direction-specific information, and then to assess which strategy was prioritized in different learning phases. We observed that, in the absence of distal cues, place fields are initially controlled by local visual cues that override idiothetic cues, but that with multiple exposures to the paradigm, spaced at intervals of days, idiothetic cues become increasingly implemented in generating an accurate spatial representation. Taken together, these data support that, in the absence of distal cues, local visual cues are prioritized in the generation of context-specific spatial representations through place cells, whereby idiothetic cues are deemed unreliable. With cumulative exposures to the environments, the animal learns to attend to subtle idiothetic cues to resolve the conflict between visual and direction-specific information.

Evaluation of Deep Learning Representations of Spatial Storm Data

Science.gov (United States)

Gagne, D. J., II; Haupt, S. E.; Nychka, D. W.

2017-12-01

The spatial structure of a severe thunderstorm and its surrounding environment provide useful information about the potential for severe weather hazards, including tornadoes, hail, and high winds. Statistics computed over the area of a storm or from the pre-storm environment can provide descriptive information but fail to capture structural information. Because the storm environment is a complex, high-dimensional space, identifying methods to encode important spatial storm information in a low-dimensional form should aid analysis and prediction of storms by statistical and machine learning models. Principal component analysis (PCA), a more traditional approach, transforms high-dimensional data into a set of linearly uncorrelated, orthogonal components ordered by the amount of variance explained by each component. The burgeoning field of deep learning offers two potential approaches to this problem. Convolutional Neural Networks are a supervised learning method for transforming spatial data into a hierarchical set of feature maps that correspond with relevant combinations of spatial structures in the data. Generative Adversarial Networks (GANs) are an unsupervised deep learning model that uses two neural networks trained against each other to produce encoded representations of spatial data. These different spatial encoding methods were evaluated on the prediction of severe hail for a large set of storm patches extracted from the NCAR convection-allowing ensemble. Each storm patch contains information about storm structure and the near-storm environment. Logistic regression and random forest models were trained using the PCA and GAN encodings of the storm data and were compared against the predictions from a convolutional neural network. All methods showed skill over climatology at predicting the probability of severe hail. However, the verification scores among the methods were very similar and the predictions were highly correlated. Further evaluations are being

Spatial and Foveal Biases, Not Perceived Mass or Heaviness, Explain the Effect of Target Size on Representational Momentum and Representational Gravity

Science.gov (United States)

De Sá Teixeira, Nuno; Oliveira, Armando Mónica

2014-01-01

The spatial memory for the last position occupied by a moving target is usually displaced forward in the direction of motion. Interpreted as a mental analogue of physical momentum, this phenomenon was coined "representational momentum" (RM). As momentum is given by the product of an object's velocity and mass, both these factors came to…

Ensemble place codes in hippocampus: CA1, CA3, and dentate gyrus place cells have multiple place fields in large environments.

Directory of Open Access Journals (Sweden)

Eunhye Park

Full Text Available Previously we reported that the hippocampus place code must be an ensemble code because place cells in the CA1 region of hippocampus have multiple place fields in a more natural, larger-than-standard enclosure with stairs that permitted movements in 3-D. Here, we further investigated the nature of hippocampal place codes by characterizing the spatial firing properties of place cells in the CA1, CA3, and dentate gyrus (DG hippocampal subdivisions as rats foraged in a standard 76-cm cylinder as well as a larger-than-standard box (1.8 m×1.4 m that did not have stairs or any internal structure to permit movements in 3-D. The rats were trained to forage continuously for 1 hour using computer-controlled food delivery. We confirmed that most place cells have single place fields in the standard cylinder and that the positional firing pattern remapped between the cylinder and the large enclosure. Importantly, place cells in the CA1, CA3 and DG areas all characteristically had multiple place fields that were irregularly spaced, as we had reported previously for CA1. We conclude that multiple place fields are a fundamental characteristic of hippocampal place cells that simplifies to a single field in sufficiently small spaces. An ensemble place code is compatible with these observations, which contradict any dedicated coding scheme.

Urbanisation and 3d Spatial - a Geometric Approach

Science.gov (United States)

Duncan, E. E.; Rahman, A. Abdul

2013-09-01

Urbanisation creates immense competition for space, this may be attributed to an increase in population owing to domestic and external tourism. Most cities are constantly exploring all avenues in maximising its limited space. Hence, urban or city authorities need to plan, expand and use such three dimensional (3D) space above, on and below the city space. Thus, difficulties in property ownership and the geometric representation of the 3D city space is a major challenge. This research, investigates the concept of representing a geometric topological 3D spatial model capable of representing 3D volume parcels for man-made constructions above and below the 3D surface volume parcel. A review of spatial data models suggests that the 3D TIN (TEN) model is significant and can be used as a unified model. The concepts, logical and physical models of 3D TIN for 3D volumes using tetrahedrons as the base geometry is presented and implemented to show man-made constructions above and below the surface parcel within a user friendly graphical interface. Concepts for 3D topology and 3D analysis are discussed. Simulations of this model for 3D cadastre are implemented. This model can be adopted by most countries to enhance and streamline geometric 3D property ownership for urban centres. 3D TIN concept for spatial modelling can be adopted for the LA_Spatial part of the Land Administration Domain Model (LADM) (ISO/TC211, 2012), this satisfies the concept of 3D volumes.

Profile of biology prospective teachers’ representation on plant anatomy learning

Science.gov (United States)

Ermayanti; Susanti, R.; Anwar, Y.

2018-04-01

This study aims to obtaining students’ representation ability in understanding the structure and function of plant tissues in plant anatomy course. Thirty students of The Biology Education Department of Sriwijaya University were involved in this study. Data on representation ability were collected using test and observation. The instruments had been validated by expert judgment. Test scores were used to represent students’ ability in 4 categories: 2D-image, 3D-image, spatial, and verbal representations. The results show that students’ representation ability is still low: 2D-image (40.0), 3D-image (25.0), spatial (20.0), and verbal representation (45.0). Based on the results of this study, it is suggested that instructional strategies be developed for plant anatomy course.

Naloxone injections into CA3 disrupt pattern completion associated with relapse from cocaine seeking

Science.gov (United States)

Kirk, Ryan A.; Clark, Jascha K.; Moore, Angela; Keefe, Kristen

2016-01-01

The goal of the present research was to assess the degree to which a pattern completion process operates in cue-induced relapse to cocaine-seeking behavior. Using a novel cue-preference version of the place preference task, rats were administered cocaine or saline, which resulted in a preference for the cocaine-paired cues. After 21 days of abstinence and prior to the preference test, for one group, PBS or naloxone was injected into the CA3 subregion of the hippocampus and for a second group, saline or naloxone was injected systemically. The results indicated that infusions of naloxone into CA3 or systemic injections produced a marked disruption for one and two cues, but had minimal disruptive effect for three or four cues, suggesting that naloxone injections disrupt CA3 function and trigger a deficit in a pattern completion process. Thus, it appears that cue-based activation of the dorsal CA3 might be a critical trigger via a pattern completion process. Based on additional analyses it appears that there is a disruption primarily for object touches for one cue naloxone injections into the CA3 or systemic injections, but no effect on time (spatial context). PMID:26815290

Changes in CaCO3 Burial Trump the Biological Pump

Science.gov (United States)

Toggweiler, J.; Dunne, J. P.

2008-12-01

The dramatic increases in atmospheric CO2 at the ends of ice ages are usually attributed to a one-two punch coming from the ocean. First, a weakened biological pump vents organically cycled CO2 from the deep ocean via changes in the ventilation of the deep ocean around Antarctica. The initial CO2 increase is then augmented by an enhancement of CaCO3 burial due to a process called CaCO3 compensation (after Broecker, W. S and T.-H. Peng, Global Biogeochem. Cycles, 1, 15-29, 1987). Here, we argue that the importance of the biological pump has been exaggerated. The main effect comes from circulation-induced changes in the burial of CaCO3. As shown in a recent paper by Andreas Schmittner and co-authors (Schmittner, A., E. Brook and J. Ahn, Impact of the ocean's overturning circulation on atmospheric CO2, in Ocean Circulation: Mechanisms and Impacts, Geophys. Monogr. 173, A. Schmittner, J. Chiang, and S. Hemming, eds., pp. 209-246, AGU, 2007) changes in the ventilation of the deep ocean around Antarctica gave rise to 20-30 ppm increases in atmospheric CO2 every 5,000-7,000 years during isotope stages 3 and 4 (30,000 to 70,000 years ago). None of these venting events gave rise to a compensation response. Meanwhile, Jaccard et al. (Science, 308, 1003-1006, 2005) show that all the big CO2 increases during terminations through stage 11 were accompanied by huge increases in CaCO3 burial. This suggests that the enhanced burial of CaCO3 is obligatory rather than compensatory with respect to the dramatic CO2 increases. Broecker and Peng's compensation idea is based on an assumption that the rain of CaCO3 to the sea floor is the same everywhere. More specifically, it assumes that there is no spatial correlation between the production of CaCO3 at the surface and the burial on the sea floor. We find instead that the production and burial of CaCO3 tend to be co-located in regional "hot spots" and that burial in the hot spots balances the input of Ca++ and HCO3- ions in rivers. The

The Evolution of Spatial Representation During Complex Visual Data Analysis: Knowing When and How to be Exact

National Research Council Canada - National Science Library

Schunn, Christian D; Saner, Lelyn D; Trafton, J. G; Trickett, Susan B; Kirschenbaum, Susan K; Knepp, Michael; Shoup, Melanie

2005-01-01

... (weather forecasting, submarine target motion analysis, and fMRI data analysis). Internal spatial representations are coded from spontaneous gestures made during cued-recall summaries of problem solving activities...

Opposite monosynaptic scaling of BLP-vCA1 inputs governs hopefulness- and helplessness-modulated spatial learning and memory.

Science.gov (United States)

Yang, Ying; Wang, Zhi-Hao; Jin, Sen; Gao, Di; Liu, Nan; Chen, Shan-Ping; Zhang, Sinan; Liu, Qing; Liu, Enjie; Wang, Xin; Liang, Xiao; Wei, Pengfei; Li, Xiaoguang; Li, Yin; Yue, Chenyu; Li, Hong-Lian; Wang, Ya-Li; Wang, Qun; Ke, Dan; Xie, Qingguo; Xu, Fuqiang; Wang, Liping; Wang, Jian-Zhi

2016-07-14

Different emotional states lead to distinct behavioural consequences even when faced with the same challenging events. Emotions affect learning and memory capacities, but the underlying neurobiological mechanisms remain elusive. Here we establish models of learned helplessness (LHL) and learned hopefulness (LHF) by exposing animals to inescapable foot shocks or with anticipated avoidance trainings. The LHF animals show spatial memory potentiation with excitatory monosynaptic upscaling between posterior basolateral amygdale (BLP) and ventral hippocampal CA1 (vCA1), whereas the LHL show memory deficits with an attenuated BLP-vCA1 connection. Optogenetic disruption of BLP-vCA1 inputs abolishes the effects of LHF and impairs synaptic plasticity. By contrast, targeted BLP-vCA1 stimulation rescues the LHL-induced memory deficits and mimics the effects of LHF. BLP-vCA1 stimulation increases synaptic transmission and dendritic plasticity with the upregulation of CREB and intrasynaptic AMPA receptors in CA1. These findings indicate that opposite excitatory monosynaptic scaling of BLP-vCA1 controls LHF- and LHL-modulated spatial memory, revealing circuit-specific mechanisms linking emotions to memory.

Opposite monosynaptic scaling of BLP–vCA1 inputs governs hopefulness- and helplessness-modulated spatial learning and memory

Science.gov (United States)

Yang, Ying; Wang, Zhi-Hao; Jin, Sen; Gao, Di; Liu, Nan; Chen, Shan-Ping; Zhang, Sinan; Liu, Qing; Liu, Enjie; Wang, Xin; Liang, Xiao; Wei, Pengfei; Li, Xiaoguang; Li, Yin; Yue, Chenyu; Li, Hong-lian; Wang, Ya-Li; Wang, Qun; Ke, Dan; Xie, Qingguo; Xu, Fuqiang; Wang, Liping; Wang, Jian-Zhi

2016-01-01

Different emotional states lead to distinct behavioural consequences even when faced with the same challenging events. Emotions affect learning and memory capacities, but the underlying neurobiological mechanisms remain elusive. Here we establish models of learned helplessness (LHL) and learned hopefulness (LHF) by exposing animals to inescapable foot shocks or with anticipated avoidance trainings. The LHF animals show spatial memory potentiation with excitatory monosynaptic upscaling between posterior basolateral amygdale (BLP) and ventral hippocampal CA1 (vCA1), whereas the LHL show memory deficits with an attenuated BLP–vCA1 connection. Optogenetic disruption of BLP–vCA1 inputs abolishes the effects of LHF and impairs synaptic plasticity. By contrast, targeted BLP–vCA1 stimulation rescues the LHL-induced memory deficits and mimics the effects of LHF. BLP–vCA1 stimulation increases synaptic transmission and dendritic plasticity with the upregulation of CREB and intrasynaptic AMPA receptors in CA1. These findings indicate that opposite excitatory monosynaptic scaling of BLP–vCA1 controls LHF- and LHL-modulated spatial memory, revealing circuit-specific mechanisms linking emotions to memory. PMID:27411738

Structure determinations for Ca3Ti2O7, Ca4Ti3O10, Ca3.6Sr0.4Ti3O10 and a refinement of Sr3Ti2O7

International Nuclear Information System (INIS)

Elcombe, M.M.; Kisi, E.H.; Hawkins, K.D.; White, T.J.; Goodman, P.; Matheson, S.

1991-01-01

The structures of the orthorhombic Ruddlesden-Popper (A n+1 B n X 3n+1 ) phases Ca 3 Ti 2 O 7 (n=2) refined from neutron powder diffraction data at λ=1.893 A. They consist of coherent intergrowths of perovskite (CaTiO 3 ) blocks, n TiO 6 octahedra thick, with single layers of CaO having a distorted NaCl configuration. TiO 6 octahedra are tilted and distorted in a very similar fashion to those in CaTiO 3 (n=∞). This fact was used to determine the space groups of the layered structures. Convergent-beam electron diffraction patterns are best matched by calculations in the above space groups which are thus confirmed. Octahedral tilt angles increase slightly in the sequence n=2, 3, ∞. Strontium addition reduces the octahedral tilt angles because of preferential substitution of Sr on the Ca sites within the perovskite blocks of Ca 4 Ti 3 O 10 . The algorithm used to produce starting models for structure refinements is thought to be generally applicable to Ruddlesden-Popper and possibly other layered perovskite structures. It furnishes the predictions: (a) all n-even compounds in the Ca n+1 Ti n O 3n+1 series will have space group Ccm2 1 , (b) all n-odd compounds in this series will have space group Pcab, (c) all A n+1 B n X 3n+1 series for which the n=∞ end member (ABX 3 ) is isostructural with CaTiO 3 will be isostructural with the compounds reported above (e.g. Ca n+1 Zr n O 3n+1 ). (orig./WL)

Comprehending 3D Diagrams: Sketching to Support Spatial Reasoning.

Science.gov (United States)

Gagnier, Kristin M; Atit, Kinnari; Ormand, Carol J; Shipley, Thomas F

2017-10-01

Science, technology, engineering, and mathematics (STEM) disciplines commonly illustrate 3D relationships in diagrams, yet these are often challenging for students. Failing to understand diagrams can hinder success in STEM because scientific practice requires understanding and creating diagrammatic representations. We explore a new approach to improving student understanding of diagrams that convey 3D relations that is based on students generating their own predictive diagrams. Participants' comprehension of 3D spatial diagrams was measured in a pre- and post-design where students selected the correct 2D slice through 3D geologic block diagrams. Generating sketches that predicated the internal structure of a model led to greater improvement in diagram understanding than visualizing the interior of the model without sketching, or sketching the model without attempting to predict unseen spatial relations. In addition, we found a positive correlation between sketched diagram accuracy and improvement on the diagram comprehension measure. Results suggest that generating a predictive diagram facilitates students' abilities to make inferences about spatial relationships in diagrams. Implications for use of sketching in supporting STEM learning are discussed. Copyright © 2016 Cognitive Science Society, Inc.

Fine-grained, local maps and coarse, global representations support human spatial working memory.

Directory of Open Access Journals (Sweden)

Mohammad Zia Ul Haq Katshu

Full Text Available While sensory processes are tuned to particular features, such as an object's specific location, color or orientation, visual working memory (vWM is assumed to store information using representations, which generalize over a feature dimension. Additionally, current vWM models presume that different features or objects are stored independently. On the other hand, configurational effects, when observed, are supposed to mainly reflect encoding strategies. We show that the location of the target, relative to the display center and boundaries, and overall memory load influenced recall precision, indicating that, like sensory processes, capacity limited vWM resources are spatially tuned. When recalling one of three memory items the target distance from the display center was overestimated, similar to the error when only one item was memorized, but its distance from the memory items' average position was underestimated, showing that not only individual memory items' position, but also the global configuration of the memory array may be stored. Finally, presenting the non-target items at recall, consequently providing landmarks and configurational information, improved precision and accuracy of target recall. Similarly, when the non-target items were translated at recall, relative to their position in the initial display, a parallel displacement of the recalled target was observed. These findings suggest that fine-grained spatial information in vWM is represented in local maps whose resolution varies with distance from landmarks, such as the display center, while coarse representations are used to store the memory array configuration. Both these representations are updated at the time of recall.

Fine-Grained, Local Maps and Coarse, Global Representations Support Human Spatial Working Memory

Science.gov (United States)

Katshu, Mohammad Zia Ul Haq; d'Avossa, Giovanni

2014-01-01

While sensory processes are tuned to particular features, such as an object's specific location, color or orientation, visual working memory (vWM) is assumed to store information using representations, which generalize over a feature dimension. Additionally, current vWM models presume that different features or objects are stored independently. On the other hand, configurational effects, when observed, are supposed to mainly reflect encoding strategies. We show that the location of the target, relative to the display center and boundaries, and overall memory load influenced recall precision, indicating that, like sensory processes, capacity limited vWM resources are spatially tuned. When recalling one of three memory items the target distance from the display center was overestimated, similar to the error when only one item was memorized, but its distance from the memory items' average position was underestimated, showing that not only individual memory items' position, but also the global configuration of the memory array may be stored. Finally, presenting the non-target items at recall, consequently providing landmarks and configurational information, improved precision and accuracy of target recall. Similarly, when the non-target items were translated at recall, relative to their position in the initial display, a parallel displacement of the recalled target was observed. These findings suggest that fine-grained spatial information in vWM is represented in local maps whose resolution varies with distance from landmarks, such as the display center, while coarse representations are used to store the memory array configuration. Both these representations are updated at the time of recall. PMID:25259601

Learning weighted sparse representation of encoded facial normal information for expression-robust 3D face recognition

KAUST Repository

Li, Huibin

2011-10-01

This paper proposes a novel approach for 3D face recognition by learning weighted sparse representation of encoded facial normal information. To comprehensively describe 3D facial surface, three components, in X, Y, and Z-plane respectively, of normal vector are encoded locally to their corresponding normal pattern histograms. They are finally fed to a sparse representation classifier enhanced by learning based spatial weights. Experimental results achieved on the FRGC v2.0 database prove that the proposed encoded normal information is much more discriminative than original normal information. Moreover, the patch based weights learned using the FRGC v1.0 and Bosphorus datasets also demonstrate the importance of each facial physical component for 3D face recognition. © 2011 IEEE.

Allocentric and contra-aligned spatial representations of a town environment in blind people.

Science.gov (United States)

Chiesa, Silvia; Schmidt, Susanna; Tinti, Carla; Cornoldi, Cesare

2017-10-01

Evidence concerning the representation of space by blind individuals is still unclear, as sometimes blind people behave like sighted people do, while other times they present difficulties. A better understanding of blind people's difficulties, especially with reference to the strategies used to form the representation of the environment, may help to enhance knowledge of the consequences of the absence of vision. The present study examined the representation of the locations of landmarks of a real town by using pointing tasks that entailed either allocentric points of reference with mental rotations of different degrees, or contra-aligned representations. Results showed that, in general, people met difficulties when they had to point from a different perspective to aligned landmarks or from the original perspective to contra-aligned landmarks, but this difficulty was particularly evident for the blind. The examination of the strategies adopted to perform the tasks showed that only a small group of blind participants used a survey strategy and that this group had a better performance with respect to people who adopted route or verbal strategies. Implications for the comprehension of the consequences on spatial cognition of the absence of visual experience are discussed, focusing in particular on conceivable interventions. Copyright © 2017 Elsevier B.V. All rights reserved.

Electric field control of the small-polaron hopping conduction in spatial confined Pr0.7(Ca0.6Sr0.40.3MnO3/PMN-PT heterostructure

Directory of Open Access Journals (Sweden)

Hao Kuang

2017-05-01

Full Text Available The electric field dependent high-temperature small-polaron hopping conduction was investigated in patterned Pr0.7(Ca0.6Sr0.40.3MnO3 strips. The small-polaronic activation energy EA and the carrier localization were found to decrease with the reduction of the strip size. Meanwhile, a similar dependence on the strip size was also obtained for the calculated small-polaron coupling constants, which could be related to the strain relaxation in strips. These results indicate that the spatial confinement prefers to delocalize the carrier and reduce the electron-phonon interaction. Furthermore, opposite variation trends of EA under negative and positive electric field were found in the strips with small size, which could be attributed to the enhancement of polarization effect induced by the reduction of strip size.

The role of spatial boundaries in shaping long-term event representations.

Science.gov (United States)

Horner, Aidan J; Bisby, James A; Wang, Aijing; Bogus, Katrina; Burgess, Neil

2016-09-01

When remembering the past, we typically recall 'events' that are bounded in time and space. However, as we navigate our environment our senses receive a continuous stream of information. How do we create discrete long-term episodic memories from continuous input? Although previous research has provided evidence for a role of spatial boundaries in the online segmentation of our sensory experience within working memory, it is not known how this segmentation contributes to subsequent long-term episodic memory. Here we show that the presence of a spatial boundary at encoding (a doorway between two rooms) impairs participants' later ability to remember the order that objects were presented in. A sequence of two objects presented in the same room in a virtual reality environment is more accurately remembered than a sequence of two objects presented in adjoining rooms. The results are captured by a simple model in which items are associated to a context representation that changes gradually over time, and changes more rapidly when crossing a spatial boundary. We therefore provide the first evidence that the structure of long-term episodic memory is shaped by the presence of a spatial boundary and provide constraints on the nature of the interaction between working memory and long-term memory. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

The Focus of Spatial Attention Determines the Number and Precision of Face Representations in Working Memory.

Science.gov (United States)

Towler, John; Kelly, Maria; Eimer, Martin

2016-06-01

The capacity of visual working memory for faces is extremely limited, but the reasons for these limitations remain unknown. We employed event-related brain potential measures to demonstrate that individual faces have to be focally attended in order to be maintained in working memory, and that attention is allocated to only a single face at a time. When 2 faces have to be memorized simultaneously in a face identity-matching task, the focus of spatial attention during encoding predicts which of these faces can be successfully maintained in working memory and matched to a subsequent test face. We also show that memory representations of attended faces are maintained in a position-dependent fashion. These findings demonstrate that the limited capacity of face memory is directly linked to capacity limits of spatial attention during the encoding and maintenance of individual face representations. We suggest that the capacity and distribution of selective spatial attention is a dynamic resource that constrains the capacity and fidelity of working memory for faces. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Formation of ternary CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) complexes under neutral to weakly alkaline conditions.

Science.gov (United States)

Lee, Jun-Yeop; Yun, Jong-Il

2013-07-21

The chemical behavior of ternary Ca-UO2-CO3 complexes was investigated by using time-resolved laser fluorescence spectroscopy (TRLFS) in combination with EDTA complexation at pH 7-9. A novel TRLFS revealed two distinct fluorescence lifetimes of 12.7 ± 0.2 ns and 29.2 ± 0.4 ns for uranyl complexes which were formed increasingly dependent upon the calcium ion concentration, even though nearly indistinguishable fluorescence peak shapes and positions were measured for both Ca-UO2-CO3 complexes. For identifying the stoichiometric number of complexed calcium ions, slope analysis in terms of relative fluorescence intensity versus calcium concentration was employed in a combination with the complexation reaction of CaEDTA(2-) by adding EDTA. The formation of CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) was identified under given conditions and their formation constants were determined at I = 0.1 M Na/HClO4 medium, and extrapolated to infinitely dilute solution using specific ion interaction theory (SIT). As a result, the formation constants for CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) were found to be log β113(0) = 27.27 ± 0.14 and log β213(0) = 29.81 ± 0.19, respectively, providing that the ternary Ca-UO2-CO3 complexes were predominant uranium(vi) species at neutral to weakly alkaline pH in the presence of Ca(2+) and CO3(2-) ions.

Some nonunitary, indecomposable representations of the Euclidean algebra e(3)

International Nuclear Information System (INIS)

Douglas, Andrew; De Guise, Hubert

2010-01-01

The Euclidean group E(3) is the noncompact, semidirect product group E(3)≅R 3 x SO(3). It is the Lie group of orientation-preserving isometries of three-dimensional Euclidean space. The Euclidean algebra e(3) is the complexification of the Lie algebra of E(3). We construct three distinct families of finite-dimensional, nonunitary representations of e(3) and show that each representation is indecomposable. The representations of the first family are explicitly realized as subspaces of the polynomial ring F[X,Y,Z] with the action of e(3) given by differential operators. The other families are constructed via duals and tensor products of the representations within the first family. We describe subrepresentations, quotients and duals of these indecomposable representations.

3D Maps Representation Using GNG

Directory of Open Access Journals (Sweden)

Vicente Morell

2014-01-01

Full Text Available Current RGB-D sensors provide a big amount of valuable information for mobile robotics tasks like 3D map reconstruction, but the storage and processing of the incremental data provided by the different sensors through time quickly become unmanageable. In this work, we focus on 3D maps representation and propose the use of the Growing Neural Gas (GNG network as a model to represent 3D input data. GNG method is able to represent the input data with a desired amount of neurons or resolution while preserving the topology of the input space. Experiments show how GNG method yields a better input space adaptation than other state-of-the-art 3D map representation methods.

The CaV2.3 R-type voltage-gated Ca2+ channel in mouse sleep architecture.

Science.gov (United States)

Siwek, Magdalena Elisabeth; Müller, Ralf; Henseler, Christina; Broich, Karl; Papazoglou, Anna; Weiergräber, Marco

2014-05-01

Voltage-gated Ca(2+) channels (VGCCs) are key elements in mediating thalamocortical rhythmicity. Low-voltage activated (LVA) CaV 3 T-type Ca(2+) channels have been related to thalamic rebound burst firing and to generation of non-rapid eye movement (NREM) sleep. High-voltage activated (HVA) CaV 1 L-type Ca(2+) channels, on the opposite, favor the tonic mode of action associated with higher levels of vigilance. However, the role of the HVA Non-L-type CaV2.3 Ca(2+) channels, which are predominantly expressed in the reticular thalamic nucleus (RTN), still remains unclear. Recently, CaV2.3(-/-) mice were reported to exhibit altered spike-wave discharge (SWD)/absence seizure susceptibility supported by the observation that CaV2.3 mediated Ca(2+) influx into RTN neurons can trigger small-conductance Ca(2+)-activated K(+)-channel type 2 (SK2) currents capable of maintaining thalamic burst activity. Based on these studies we investigated the role of CaV2.3 R-type Ca(2+) channels in rodent sleep. The role of CaV2.3 Ca(2+) channels was analyzed in CaV2.3(-/-) mice and controls in both spontaneous and artificial urethane-induced sleep, using implantable video-EEG radiotelemetry. Data were analyzed for alterations in sleep architecture using sleep staging software and time-frequency analysis. CaV2.3 deficient mice exhibited reduced wake duration and increased slow-wave sleep (SWS). Whereas mean sleep stage durations remained unchanged, the total number of SWS epochs was increased in CaV2.3(-/-) mice. Additional changes were observed for sleep stage transitions and EEG amplitudes. Furthermore, urethane-induced SWS mimicked spontaneous sleep results obtained from CaV2.3 deficient mice. Quantitative Real-time PCR did not reveal changes in thalamic CaV3 T-type Ca(2+) channel expression. The detailed mechanisms of SWS increase in CaV2.3(-/-) mice remain to be determined. Low-voltage activated CaV2.3 R-type Ca(2+) channels in the thalamocortical loop and extra

New 3D gas density maps of NaI and CaII interstellar absorption within 300 pc

Science.gov (United States)

Welsh, B. Y.; Lallement, R.; Vergely, J.-L.; Raimond, S.

2010-02-01

Aims: We present new high resolution (R > 50 000) absorption measurements of the NaI doublet (5889-5895 Å) along 482 nearby sight-lines, in addition to 807 new measurements of the CaII K (3933 Å) absorption line. We have combined these new data with previously reported measurements to produce a catalog of absorptions towards a total of 1857 early-type stars located within 800 pc of the Sun. Using these data we have determined the approximate 3-dimensional spatial distribution of neutral and partly ionized interstellar gas density within a distance-cube of 300 pc from the Sun. Methods: All newly recorded spectra were analyzed by means of a multi-component line profile-fitting program, in most cases using simultaneous fits to the line doublets. Normalized absorption profiles were fitted by varying the velocity, doppler width and column density for all intervening interstellar clouds. The resulting total column densities were then used in conjunction with the Hipparcos distances of the target stars to construct inversion maps of the 3D spatial density distribution of the NaI and CaII bearing gas. Results: A plot of the equivalent width of NaI versus distance reveals a wall of neutral gas at ~80 pc that can be associated with the boundary wall to the central rarefied Local Cavity region. In contrast, a similar plot for the equivalent width of CaII shows no sharply increasing absorption at 80 pc, but instead we observe a slowly increasing value of CaII equivalent width with increasing sight-line distance sampled. Low values for the volume density of NaI (nNaI values in the range 10-8 >nNaI > 10-10 cm-3 are found for sight-lines with distance >300 pc. Both high and low values of the volume density of CaII (nCaII) are found for sight-lines 100 pc a value of nCaII ~ 10-9 cm-3 is typical for most sight-lines, indicating that the distribution of CaII bearing gas is fairly uniform throughout the general ISM. Our three maps of the 3D spatial distribution of local neutral Na

Ab-initio calculations of the Ruddlesden-Popper phases CaMnO3, CaO(CaMnO3) and CaO(CaMnO3)2

International Nuclear Information System (INIS)

Cardoso, C; Borges, R P; Gasche, T; Godinho, M

2008-01-01

The present work reports ab-initio density functional theory calculations for the Ruddlesden-Popper phase CaO(CaMnO 3 ) n compounds. In order to study the evolution of the properties with the number of perovskite layers, a detailed analysis of the densities of states calculated for each compound and for several magnetic configurations was performed. The effect of distortions of the crystal structure on the magnetic ground state is also analysed and the exchange constants and transition temperatures are calculated for the three compounds using a mean field model. The calculated magnetic ground state structures and magnetic moments are in good agreement with experimental results and previous calculations

The system La(PO3)3-Ca(PO3)2-P2O5

International Nuclear Information System (INIS)

Jungowska, W.; Znamierowska, T.

1993-01-01

Ternary system La(PO 3 ) 3 -Ca(PO 3 ) 2 -P 2 O 5 has been studied by means of thermal and roentgenography analysis. The existence of single intermediate compound CaLa(PO 3 ) 5 has been observed. The phase diagrams for the ternary system as well as for two binary systems La(PO 3 ) 3 -Ca(PO 3 ) 2 and CaLa(PO 3 ) 5 -LaP 5 O 11 have been shown. 7 refs, 3 figs

Ca 3d unoccupied states in Bi2Sr2CaCu2O8 investigated by Ca L2,3 x-ray-absorption near-edge structure

International Nuclear Information System (INIS)

Borg, A.; King, P.L.; Pianetta, P.; Lindau, I.; Mitzi, D.B.; Kapitulnik, A.; Soldatov, A.V.; Della Longa, S.; Bianconi, A.

1992-01-01

The high-resolution Ca L 2,3 x-ray-absorption near-edge-structure (XANES) spectrum of a Bi 2 Sr 2 CaCu 2 O 8 single crystal has been measured by use of a magnetic-projection x-ray microscope probing a surface area of 200x200 μm 2 . The Ca L 2,3 XANES spectrum is analyzed by performing a multiple-scattering XANES calculation in real space and comparing the results with the spectrum of CaF 2 . Good agreement between the calculated and experimental crystal-field splitting Δ f of the Ca 3d final states is found and the splitting is shown to be smaller by 0.5 eV than in the initial state. The Ca 3d partial density of states is found to be close to the Fermi level in the initial state. The Ca-O(in plane) distance is shown to be a critical parameter associated with the shift of the Ca 3d states relative to the Fermi level; in particular, we have studied the effect of the out-of-plane dimpling mode of the in-plane oxygen atoms O(in plane) that will move the Ca 3d states on or off the Fermi level. This mode can therefore play a role in modulating the charge transfer between the two CuO 2 planes separated by the Ca ions

Ca 3d unoccupied states in Bi2Sr2CaCu2O8 investigated by Ca L2,3 x-ray-absorption near-edge structure

Energy Technology Data Exchange (ETDEWEB)

Borg, A; King, P L; Pianetta, P; Lindau, I; Mitzi, D B

1992-01-01

The high-resolution Ca L(2,3) x-ray-absorption near-edge-structure (XANES) spectrum of a Bi2Sr2CaCu2O8 single crystal has been measured by use of a magnetic-projection x-ray microscope probing a surface area of 200x200 micrometers square. The Ca L(2,3) XANES spectrum is analyzed by performing a multiple-scattering XANES calculation in real space and comparing the results with the spectrum of CaF2. Good agreement between the calculated and experimental crystal-field splitting Delta f of the Ca 3d final states is found and the splitting is shown to be smaller by 0.5 eV than in the initial state. The Ca 3d partial density of states is found to be close to the Fermi level in the initial state. The Ca-O (in plane) distance is shown to be a critical parameter associated with the shift of the Ca 3d states relative to the Fermi level; in particular, the authors have studied the effect of the out-of-plane dimpling mode of the in-plane oxygen atoms O(in plane) that will move the Ca 3d states on or off the Fermi level. This mode can therefore play a role in modulating the charge transfer between the two CuO2 planes separated by the Ca ions.

Identities for the electron forms 2 and their 3D representation

International Nuclear Information System (INIS)

Minogin, Vladimir G.

2012-01-01

New type of identities for products of the electron forms 2 (Fs2) and the bilinear forms (BFs) are derived. The identities are found for both temporal Fs2 describing the electron energy and quasi energy densities and spatial Fs2 describing the linear momentum and quasi linear momentum densities. The identities allow one to transform the quasi energy densities into the energy densities as well as the quasi linear momentum densities into the linear momentum densities. It is shown that by choosing any one of the 16 electron temporal or spatial Fs2 one can represent the remaining 15 temporal or spatial Fs2 as combinations of a chosen form 2 (F2) and the derivatives of a number of BFs. Any one of such 16 sets of identities can be considered as a specific form of an irreducible representation for the temporal or spatial Fs2. Similar to the bilinear identities for BFs the derived identities can be used for reduction different physical quantities describing the electron to the forms defined by the basic physical observables. As an example we consider transformation of the electron energy density to a new fundamental form that presents the energy density through the linear momentum density. - Highlights: ► New type of identities connecting electron forms 2 and bilinear forms is derived.► Identities are found for temporal and spatial forms 2. ► Irreducible representation of the identities is derived. ► New forms of the electron energy density are presented.

Spatial representation of organic carbon and active-layer thickness of high latitude soils in CMIP5 earth system models

Energy Technology Data Exchange (ETDEWEB)

Mishra, Umakant; Drewniak, Beth; Jastrow, Julie D.; Matamala, Roser M.; Vitharana, U. W. A.

2017-08-01

Soil properties such as soil organic carbon (SOC) stocks and active-layer thickness are used in earth system models (F.SMs) to predict anthropogenic and climatic impacts on soil carbon dynamics, future changes in atmospheric greenhouse gas concentrations, and associated climate changes in the permafrost regions. Accurate representation of spatial and vertical distribution of these soil properties in ESMs is a prerequisite for redudng existing uncertainty in predicting carbon-climate feedbacks. We compared the spatial representation of SOC stocks and active-layer thicknesses predicted by the coupled Modellntercomparison Project Phase 5 { CMIP5) ESMs with those predicted from geospatial predictions, based on observation data for the state of Alaska, USA. For the geospatial modeling. we used soil profile observations {585 for SOC stocks and 153 for active-layer thickness) and environmental variables (climate, topography, land cover, and surficial geology types) and generated fine-resolution (50-m spatial resolution) predictions of SOC stocks (to 1-m depth) and active-layer thickness across Alaska. We found large inter-quartile range (2.5-5.5 m) in predicted active-layer thickness of CMIP5 modeled results and small inter-quartile range (11.5-22 kg m-2) in predicted SOC stocks. The spatial coefficient of variability of active-layer thickness and SOC stocks were lower in CMIP5 predictions compared to our geospatial estimates when gridded at similar spatial resolutions (24.7 compared to 30% and 29 compared to 38%, respectively). However, prediction errors. when calculated for independent validation sites, were several times larger in ESM predictions compared to geospatial predictions. Primaly factors leading to observed differences were ( 1) lack of spatial heterogeneity in ESM predictions, (2) differences in assumptions concerning environmental controls, and (3) the absence of pedogenic processes in ESM model structures. Our results suggest that efforts to incorporate

IP3 stimulates CA++ efflux from fusogenic carrot protoplasts

International Nuclear Information System (INIS)

Rincon, M.; Boss, W.F.

1986-01-01

Polyphosphoinositide breakdown plays an important role in signal transduction in animal cells (Berridge and Irvine, 1984, Nature, 312:315). Upon stimulation, phospholipase C hydrolyzes phosphatidylinositol 4,5-bisphosphate to inositol 1,4,5-trisphosphate (IP 3 ) and diacylglycerol both of which act as cellular second messengers. IP 3 mobilizes Ca ++ from internal stores, hence the cytosolic free Ca ++ concentration increases and those physiological activities regulated by Ca ++ are stimulated. To test if plant cells also responded to IP 3 , Ca ++ efflux studies were done with fusogenic carrot protoplasts released in EGTA. The protoplasts were preloaded with 45 Ca ++ placed in a Ca ++ -free medium, and efflux determined as 45 Ca ++ loss from the protoplasts. IP 3 (10-20μM) caused enhanced 45 Ca ++ efflux and the response was sustained for at least 15 min. In plants, as in animals, the observed IP 3 -enhanced 45 Ca ++ efflux suggested that IP 3 released Ca ++ from internal stores, and the increased free cytosolic Ca ++ activated Ca ++ pumping mechanisms which restored the Ca ++ concentration in the cytosol to the normal level

High-pressure synthesis and structural, physical properties of CaIr1-xPtxO3 and CaIr1-xRhxO3

Science.gov (United States)

Hirai, S.; Bromiley, G. D.; Klemme, S.; Irifune, T.; Ohfuji, H.; Attfield, P.; Nishiyama, N.

2010-12-01

Since the discovery of the perovskite to post-perovskite transition in MgSiO3 in a laser-heated DAC, wide attention has been focussed on the post-perovskite phase of MgSiO3. This is because the post-perovskite phase is likely to play a key role in Earth’s lowermost mantle, and because the perovskite to post-perovskite transition can explain many features of the D” seismic discontinuity. While it is meaningful to conduct further studies of MgSiO3, the post-perovskite phase of MgSiO3 cannot be quenched to ambient pressure/temperature conditions. Thus, further studies must be conducted using analogue compounds of MgSiO3 post-perovskite, which are quenchable to ambient pressure/temperature conditions. The post-perovskite phase of MgSiO3 crystallizes in a layered structure with CaIrO3-structure. Therefore, it is useful to investigate compounds with CaIrO3-structure. There are only four quenchable oxides with CaIrO3-structure reported to date: CaIrO3, CaPtO3, CaRhO3 and CaRuO3. CaIrO3 can be synthesized at ambient pressure, whilst the other three oxides can only be obtained at high pressure/temperature conditions using a multi-anvil apparatus. Further studies on these materials have revealed structural phase transitions at high P-T and a metal-insulator transition by hole doping. In the case of CaIrO3, The post-perovskite phase of CaIrO3 synthesized at 2GPa, 1373K transforms into a perovskite phase at 2GPa, 1673K. In other words, the perovskite phase can be synthesized at temperatures higher than those needed for synthesizing the post-perovskite phase. This is also the case for CaRhO3 (6GPa, 1873K) and CaRuO3 (23GPa, 1343K), while CaPtO3 remained post-perovskite at higher temperatures. We have succeeded in synthesizing solid solutions between CaIrO3, CaPtO3 and CaRhO3. We have found the systematic change in structural and physical properties of post-perovskite oxides, with composition and P-T, which broadens the future opportunity for studying post-perovskite systems

Getting to Know a Place: Built Environment Walkability and Children's Spatial Representation of Their Home-School (h-s) Route.

Science.gov (United States)

Moran, Mika R; Eizenberg, Efrat; Plaut, Pnina

2017-06-06

The literature on environmental walkability to date has mainly focused on walking and related health outcomes. While previous studies suggest associations between walking and spatial knowledge, the associations between environmental walkability and spatial knowledge is yet to be explored. The current study addresses this lacuna in research by exploring children's mental representations of their home-school (h-s) route, vis.

A Lightweight AV System for Providing a Faithful and Spatially Manipulable Visual Hand Representation

OpenAIRE

Pusch , Andreas; Martin , Olivier; Coquillart , Sabine

2011-01-01

Session: Developing new tools and technologies - Abstracts to be published in a regular issue of the journal Cyberpsychology, Behavior and Social Networking (indexed in MedLine and PsychInfo): http://online.liebertpub.com/loi/CYBER; International audience; This paper introduces the technical foundations of a system designed to embed a lightweight, faithful and spatially manipulable representation of the user's hand into an otherwise virtual world (aka Augmented Virtuality, AV). A highly intui...

EFFECT OF FERRITE PHASE ON THE FORMATION AND COEXISTENCE OF 3CaO.3Al₂O₃.CaSO₄ AND 3CaO.SiO₂ MINERALS

Directory of Open Access Journals (Sweden)

Xiaolei Lu

2017-12-01

Full Text Available The effect of ferrite on the formation and coexistence of 3CaO.3Al₂O₃.CaSO₄ (C₄A₃$ and 3CaO.SiO₂ (C3S was investigated in this paper. The results indicate that 20 % content of ferrite phase with the composition of C₂A0.5F0.5 can facilitate the coexistence of C₄A₃$ and C₃S solid solutions at 1350 ° C. There are other trace elements that incorporate into clinker minerals and form solid solutions. In addition, the dark and polygonal C₄A₃$ solid solution is not dissolved in liquid phase at 1350 ° C. It can promote the burnability of the raw mixes and provide a favorable condition for the formation of C₃S. However, it has an adverse effect on the coexistence of two clinker minerals with the changing of ferrite compositions. This will provide the important basis for the preparation of the calcium sulphoaluminate cement clinker containing C₃S.

Towards a 3d Spatial Urban Energy Modelling Approach

Science.gov (United States)

Bahu, J.-M.; Koch, A.; Kremers, E.; Murshed, S. M.

2013-09-01

Today's needs to reduce the environmental impact of energy use impose dramatic changes for energy infrastructure and existing demand patterns (e.g. buildings) corresponding to their specific context. In addition, future energy systems are expected to integrate a considerable share of fluctuating power sources and equally a high share of distributed generation of electricity. Energy system models capable of describing such future systems and allowing the simulation of the impact of these developments thus require a spatial representation in order to reflect the local context and the boundary conditions. This paper describes two recent research approaches developed at EIFER in the fields of (a) geo-localised simulation of heat energy demand in cities based on 3D morphological data and (b) spatially explicit Agent-Based Models (ABM) for the simulation of smart grids. 3D city models were used to assess solar potential and heat energy demand of residential buildings which enable cities to target the building refurbishment potentials. Distributed energy systems require innovative modelling techniques where individual components are represented and can interact. With this approach, several smart grid demonstrators were simulated, where heterogeneous models are spatially represented. Coupling 3D geodata with energy system ABMs holds different advantages for both approaches. On one hand, energy system models can be enhanced with high resolution data from 3D city models and their semantic relations. Furthermore, they allow for spatial analysis and visualisation of the results, with emphasis on spatially and structurally correlations among the different layers (e.g. infrastructure, buildings, administrative zones) to provide an integrated approach. On the other hand, 3D models can benefit from more detailed system description of energy infrastructure, representing dynamic phenomena and high resolution models for energy use at component level. The proposed modelling strategies

Temporal and spatial differences in intracellular Ca++ changes elicited by K+ and glutamate in single cultured neocortical neurons

DEFF Research Database (Denmark)

Belhage, B; Frandsen, A; Schousboe, A

1996-01-01

characteristics of voltage gated Ca++ channels are dramatically different in cell bodies and neurites. Moreover, the distribution of L-type channels activated by glutamate differs in cell bodies and neurites. Such differences in the spatial distribution of Ca++ channels are likely to be of major importance...... after exposure to K+. The Ca++ channel blockers verapamil and nifedipine affecting N- and L-type channels, respectively had differential effects on K+ stimulated increases in [Ca++]i. Nifedipine only affected the increase marginally whereas verapamil inhibited the response by 50-60% both in cell bodies...

Image Simulation and Assessment of the Colour and Spatial Capabilities of the Colour and Stereo Surface Imaging System (CaSSIS) on the ExoMars Trace Gas Orbiter

Science.gov (United States)

Tornabene, Livio L.; Seelos, Frank P.; Pommerol, Antoine; Thomas, Nicholas; Caudill, C. M.; Becerra, Patricio; Bridges, John C.; Byrne, Shane; Cardinale, Marco; Chojnacki, Matthew; Conway, Susan J.; Cremonese, Gabriele; Dundas, Colin M.; El-Maarry, M. R.; Fernando, Jennifer; Hansen, Candice J.; Hansen, Kayle; Harrison, Tanya N.; Henson, Rachel; Marinangeli, Lucia; McEwen, Alfred S.; Pajola, Maurizio; Sutton, Sarah S.; Wray, James J.

2018-02-01

This study aims to assess the spatial and visible/near-infrared (VNIR) colour/spectral capabilities of the 4-band Colour and Stereo Surface Imaging System (CaSSIS) aboard the ExoMars 2016 Trace Grace Orbiter (TGO). The instrument response functions for the CaSSIS imager was used to resample spectral libraries, modelled spectra and to construct spectrally ( i.e., in I/F space) and spatially consistent simulated CaSSIS image cubes of various key sites of interest and for ongoing scientific investigations on Mars. Coordinated datasets from Mars Reconnaissance Orbiter (MRO) are ideal, and specifically used for simulating CaSSIS. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) provides colour information, while the Context Imager (CTX), and in a few cases the High-Resolution Imaging Science Experiment (HiRISE), provides the complementary spatial information at the resampled CaSSIS unbinned/unsummed pixel resolution (4.6 m/pixel from a 400-km altitude). The methodology used herein employs a Gram-Schmidt spectral sharpening algorithm to combine the ˜18-36 m/pixel CRISM-derived CaSSIS colours with I/F images primarily derived from oversampled CTX images. One hundred and eighty-one simulated CaSSIS 4-colour image cubes (at 18-36 m/pixel) were generated (including one of Phobos) based on CRISM data. From these, thirty-three "fully"-simulated image cubes of thirty unique locations on Mars ( i.e., with 4 colour bands at 4.6 m/pixel) were made. All simulated image cubes were used to test both the colour capabilities of CaSSIS by producing standard colour RGB images, colour band ratio composites (CBRCs) and spectral parameters. Simulated CaSSIS CBRCs demonstrated that CaSSIS will be able to readily isolate signatures related to ferrous (Fe2+) iron- and ferric (Fe3+) iron-bearing deposits on the surface of Mars, ices and atmospheric phenomena. Despite the lower spatial resolution of CaSSIS when compared to HiRISE, the results of this work demonstrate that Ca

Representation of Numerical and Non-Numerical Order in Children

Science.gov (United States)

Berteletti, Ilaria; Lucangeli, Daniela; Zorzi, Marco

2012-01-01

The representation of numerical and non-numerical ordered sequences was investigated in children from preschool to grade 3. The child's conception of how sequence items map onto a spatial scale was tested using the Number-to-Position task (Siegler & Opfer, 2003) and new variants of the task designed to probe the representation of the alphabet…

Photoluminescence and thermoluminescence characterization of Eu3+- and Dy3+ -activated Ca3(PO4)2 phosphor

International Nuclear Information System (INIS)

Nagpure, I.M.; Saha, Subhajit; Dhoble, S.J.

2009-01-01

Rare-earth-doped polycrystalline Ca 3 (PO 4 ) 2 :Eu, Ca 3 (PO 4 ) 2 :Dy and Ca 3 (PO 4 ) 2 :Eu,Dy phosphors prepared by a modified solid-state synthesis has been studied for its X-ray diffraction, thermoluminescence (TL) and photoluminescence (PL) characteristics. The PL emission spectra of the phosphor suggest the presence of Eu 3+ ion in Ca 3 (PO 4 ) 2 :Eu and Dy 3+ ion in Ca 3 (PO 4 ) 2 :Dy lattice sites. The TL glow curve of the Ca 3 (PO 4 ) 2 :Eu compounds has a simple structure with a prominent peak at 228 deg. C, while Ca 3 (PO 4 ) 2 :Dy peaking at 146 and 230 deg. C. TL sensitivity of phosphors are compared with CaSO 4 : Dy and found 1.52 and 1.20 times less in Ca 3 (PO 4 ) 2 :Eu and Ca 3 (PO 4 ) 2 :Dy phosphors, respectively. The Ca 3 (PO 4 ) 2 :Eu,Dy phosphors shows switching behavior under two different excitation wavelengths and enhancement in PL intensity of Dy 3+ ions were reported. The paper discusses the photoluminescence and thermoluminescence behavior of Eu 3+ and Dy 3+ ion in Ca 3 (PO 4 ) 2 hosts, it may be applicable to solid-state lighting as well as thermoluminescence dosimetry applications.

Magnetic structures of iron-based materials. Through complex magnetism of CaFe4As3

International Nuclear Information System (INIS)

Nambu, Yusuke

2011-01-01

Magnetism of interpenetrating FeAs strips in the orthorhombic CaFe 4 As 3 was examined through neutron diffraction. Incommensurate and predominantly longitudinally (parallel b) modulated order develops through a 2nd order phase transition at T N - 90 K. A 1st order transition at T 2 - 26 K is associated with the development of components in a separate irreducible representation, locking the wave vector to 3b*/8. The ab-initio Fermi surface features sheets separated by near the observed wave vector. However, Fermi surface nesting seems to have a limited role, instead magnetic structures could result from competing 2nd and 3rd nearest neighbor interactions in a localized spin picture. (author)

Impacts of spatial resolution and representation of flow connectivity on large-scale simulation of floods

OpenAIRE

C. M. R. Mateo; C. M. R. Mateo; D. Yamazaki; D. Yamazaki; H. Kim; A. Champathong; J. Vaze; T. Oki; T. Oki

2017-01-01

Global-scale river models (GRMs) are core tools for providing consistent estimates of global flood hazard, especially in data-scarce regions. Due to former limitations in computational power and input datasets, most GRMs have been developed to use simplified representations of flow physics and run at coarse spatial resolutions. With increasing computational power and improved datasets, the application of GRMs to finer resolutions is becoming a reality. To support development...

Spatial organization of NG2 glial cells and astrocytes in rat hippocampal CA1 region.

Science.gov (United States)

Xu, Guangjin; Wang, Wei; Zhou, Min

2014-04-01

Similar to astrocytes, NG2 glial cells are uniformly distributed in the central nervous system (CNS). However, little is known about the interspatial relationship, nor the functional interactions between these two star-shaped glial subtypes. Confocal morphometric analysis showed that NG2 immunostained cells are spatially organized as domains in rat hippocampal CA1 region and that each NG2 glial domain occupies a spatial volume of ∼178, 364 μm(3) . The processes of NG2 glia and astrocytes overlap extensively; each NG2 glial domain interlaces with the processes deriving from 5.8 ± 0.4 neighboring astrocytes, while each astrocytic domain accommodates processes stemming from 4.5 ± 0.3 abutting NG2 glia. In CA1 stratum radiatum, the cell bodies of morphologically identified glial cells often appear to make direct somatic-somata contact, termed as doublets. We used dual patch recording and postrecording NG2/GFAP double staining to determine the glial identities of these doublets. We show that among 44 doublets, 50% were NG2 glia-astrocyte pairs, while another 38.6% and 11.4% were astrocyte-astrocyte and NG2 glia-NG2 glia pairs, respectively. In dual patch recording, neither electrical coupling nor intercellular biocytin transfer was detected in astrocyte-NG2 glia or NG2 glia-NG2 glia doublets. Altogether, although NG2 glia and astrocytes are not gap junction coupled, their cell bodies and processes are interwoven extensively. The anatomical and physiological relationships revealed in this study should facilitate future studies to understand the metabolic coupling and functional communication between NG2 glia and astrocytes. Copyright © 2013 Wiley Periodicals, Inc.

Developing Spatial Knowledge in the Absence of Vision: Allocentric and Egocentric Representations Generated by Blind People When Supported by Auditory Cues

Directory of Open Access Journals (Sweden)

Luca Latini Corazzini

2010-10-01

Full Text Available The study of visuospatial representations and visuospatial memory can profit from the analysis of the performance of specific groups. in particular, the surprising skills and limitations of blind people may be an important source of information. For example, converging evidence indicates that, even though blind individuals are able to develop both egocentric and allocentric space representations, the latter tend to be much more restricted than those in blindfolded sighted individuals. however, no study has explored yet whether this conclusion also holds when people receive practice with the spatial environment and are supported by auditory stimuli. The present research examined these issues with the use of an experimental apparatus based on the morris Water maze (morris et al., 1982. in this setup, blind people and blindfolded controls were given the opportunity to develop knowledge of the environment with the support of simultaneous auditory cues. The results show that even in this favourable case blind people spontaneously maintain to rely on an egocentric spatial representation.

Content-adaptive pyramid representation for 3D object classification

DEFF Research Database (Denmark)

Kounalakis, Tsampikos; Boulgouris, Nikolaos; Triantafyllidis, Georgios

2016-01-01

In this paper we introduce a novel representation for the classification of 3D images. Unlike most current approaches, our representation is not based on a fixed pyramid but adapts to image content and uses image regions instead of rectangular pyramid scales. Image characteristics, such as depth...... and color, are used for defining regions within images. Multiple region scales are formed in order to construct the proposed pyramid image representation. The proposed method achieves excellent results in comparison to conventional representations....

Role of electron correlation and long range magnetic order in the electronic structure of Ca(Sr)RuO3

International Nuclear Information System (INIS)

Singh, Ravi Shankar; Medicherla, V.R.R.; Maiti, Kalobaran

2008-01-01

The room temperature photoemission spectra collected at different surface sensitivities reveal qualitatively different surface and bulk electronic structures in CaRuO 3 and SrRuO 3 . The extracted bulk spectra are dominated by the coherent feature intensity with a weak correlation induced feature at higher binding energies. The First principle calculations provide a wonderful representation of the bulk spectra for the effective electron correlation strength, U/W∼0.2 as expected for highly extended 4d systems. This resolves a long-standing issue that arose due to the prediction of large U/W similar to 3d systems. Photoemission spectra across the magnetic phase transition reveal unusual evolution exhibiting a large reduction in the coherent feature intensity in the bulk spectrum of SrRuO 3 , while the bulk spectrum in CaRuO 3 remains almost the same down to the lowest temperature studied

Mucins CA 125, CA 19.9, CA 15.3 and TAG-72.3 as tumor markers in patients with lung cancer: comparison with CYFRA 21-1, CEA, SCC and NSE.

Science.gov (United States)

Molina, Rafael; Auge, Jose Maria; Escudero, Jose Miguel; Marrades, Ramon; Viñolas, Nuria; Carcereny, Emilio; Ramirez, Jose; Filella, Xavier

2008-01-01

Tumor marker serum levels were prospectively studied in 289 patients with suspected, but unconfirmed, lung cancer and in 513 patients with lung cancer [417 non-small cell lung cancer (NSCLC) patients and 96 small cell lung cancer (SCLC) patients]. In patients with benign disease, abnormal serum levels were found for the following tumor markers: CEA (in 6.6% of patients); CA 19.9 (6.2%); CA 125 (28.7%); NSE (0.7%); CYFRA (8.7%); TAG-72.3 (4.2%); SCC (3.5%), and CA 15.3 (3.5%). Excluding patients with renal failure or liver diseases, tumor marker specificity improved with abnormal levels in 0.5% for NSE, 0.9% for SCC, 2.8% for CEA, CA 15.3 and TAG-72.3, 3.8% for CA 19.9, 4.2% for CYFRA and 21.4% for CA 125. Excluding CA 125, one of the markers was abnormal in 15% of patients without malignancy. Tumor marker sensitivity was related to cancer histology and tumor extension. NSE had the highest sensitivity in SCLC and CYFRA and CEA in NSCLC. Significantly higher concentrations of CEA, SCC, CA 125, CA 15.3 and TAG-72.3 were found in NSCLC than in SCLC. Likewise, significantly higher CEA (p tumors. Using a combination of 3 tumor markers (CEA, CYFRA 21-1 in all histologies, SCC in squamous tumors and CA 15.3 in adenocarcinomas), a high sensitivity may be achieved in all histological types. Tumor markers may be useful in the histological differentiation of NSCLC and SCLC. Using specific criteria for the differentiation of SCLC and NSCLC, the sensitivity was 84.2 and 68.8%, the specificity was 93.8 and 99.7%, the positive predictive value was 98.3 and 98.5% and the negative predictive value was 57.7 and 93.3%, respectively. Copyright 2008 S. Karger AG, Basel.

Getting to Know a Place: Built Environment Walkability and Children’s Spatial Representation of Their Home-School (h–s Route

Directory of Open Access Journals (Sweden)

Mika R. Moran

2017-06-01

Full Text Available The literature on environmental walkability to date has mainly focused on walking and related health outcomes. While previous studies suggest associations between walking and spatial knowledge, the associations between environmental walkability and spatial knowledge is yet to be explored. The current study addresses this lacuna in research by exploring children’s mental representations of their home-school (h–s route, vis-

Impacts of spatial resolution and representation of flow connectivity on large-scale simulation of floods

OpenAIRE

Mateo, Cherry May R.; Yamazaki, Dai; Kim, Hyungjun; Champathong, Adisorn; Vaze, Jai; Oki, Taikan

2017-01-01

Global-scale River Models (GRMs) are core tools for providing consistent estimates of global flood hazard, especially in data-scarce regions. Due to former limitations in computational power and input datasets, most GRMs have been developed to use simplified representation of flow physics and run at coarse spatial resolutions. With increasing computational power and improved datasets, the application of GRMs to finer resolutions is becoming a reality. To support development in this direction,...

Image simulation and assessment of the colour and spatial capabilities of the Colour and Stereo Surface Imaging System (CaSSIS) on the ExoMars Trace Gas Orbiter

Science.gov (United States)

Tornabene, Livio L.; Seelos, Frank P.; Pommerol, Antoine; Thomas, Nicolas; Caudill, Christy M.; Becerra, Patricio; Bridges, John C.; Byrne, Shane; Cardinale, Marco; Chojnacki, Matthew; Conway, Susan J.; Cremonese, Gabriele; Dundas, Colin M.; El-Maarry, M. R.; Fernando, Jennifer; Hansen, Candice J.; Hansen, Kayle; Harrison, Tanya N.; Henson, Rachel; Marinangeli, Lucia; McEwen, Alfred S.; Pajola, Maurizio; Sutton, Sarah S.; Wray, James J.

2018-01-01

This study aims to assess the spatial and visible/near-infrared (VNIR) colour/spectral capabilities of the 4-band Colour and Stereo Surface Imaging System (CaSSIS) aboard the ExoMars 2016 Trace Grace Orbiter (TGO). The instrument response functions for the CaSSIS imager was used to resample spectral libraries, modelled spectra and to construct spectrally (i.e., in I/F space) and spatially consistent simulated CaSSIS image cubes of various key sites of interest and for ongoing scientific investigations on Mars. Coordinated datasets from Mars Reconnaissance Orbiter (MRO) are ideal, and specifically used for simulating CaSSIS. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) provides colour information, while the Context Imager (CTX), and in a few cases the High-Resolution Imaging Science Experiment (HiRISE), provides the complementary spatial information at the resampled CaSSIS unbinned/unsummed pixel resolution (4.6 m/pixel from a 400-km altitude). The methodology used herein employs a Gram-Schmidt spectral sharpening algorithm to combine the ∼18–36 m/pixel CRISM-derived CaSSIS colours with I/F images primarily derived from oversampled CTX images. One hundred and eighty-one simulated CaSSIS 4-colour image cubes (at 18–36 m/pixel) were generated (including one of Phobos) based on CRISM data. From these, thirty-three “fully”-simulated image cubes of thirty unique locations on Mars (i.e., with 4 colour bands at 4.6 m/pixel) were made. All simulated image cubes were used to test both the colour capabilities of CaSSIS by producing standard colour RGB images, colour band ratio composites (CBRCs) and spectral parameters. Simulated CaSSIS CBRCs demonstrated that CaSSIS will be able to readily isolate signatures related to ferrous (Fe2+) iron- and ferric (Fe3+) iron-bearing deposits on the surface of Mars, ices and atmospheric phenomena. Despite the lower spatial resolution of CaSSIS when compared to HiRISE, the results of this work demonstrate that

Filling the holes in the CaFe4As3 structure: Synthesis and magnetism of CaCo5As3

Science.gov (United States)

Rosa, P. F. S.; Scott, B. L.; Ronning, F.; Bauer, E. D.; Thompson, J. D.

2017-07-01

Here, we investigate single crystals of CaCo5As3 by means of single-crystal x-ray diffraction, microprobe, magnetic susceptibility, heat capacity, and pressure-dependent transport measurements. CaCo5As3 shares the same structure of CaFe4As3 with an additional Co atom filling a lattice vacancy and undergoes a magnetic transition at TM=16 K associated with a frustrated magnetic order. CaCo5As3 displays metallic behavior and its Sommerfeld coefficient (γ =70 mJ/mol K2) indicates a moderate enhancement of electron-electron correlations. Transport data under pressures to 2.5 GPa reveal a suppression of TM at a rate of -0.008 K/GPa. First-principles electronic structure calculations show a complex three-dimensional band structure and magnetic moments that depend on the local environment at each Co site. Our results are compared with previous data on CaFe4As3 and provide a scenario for a magnetically frustrated ground state in this family of compounds.

Representations of braid group obtained from quantum sl(3) enveloping algebra

International Nuclear Information System (INIS)

Ma Zhongqi.

1989-07-01

The quantum Clebsch-Gordan coefficients for the coproduct 6x6 of the quantum sl(3) enveloping algebra are computed. Based on the representation 6, the representation of the braid group and the corresponding link polynomial are obtained. The link polynomials based on the representations of the quantum sl(3) enveloping algebra with one row Young tableau are discussed. (author). 11 refs, 3 tabs

Ischemic damage in hippocampal CA1 is dependent on glutamate release and intact innervation from CA3

DEFF Research Database (Denmark)

Benveniste, H; Jørgensen, M B; Sandberg, M

1989-01-01

The removal of glutamatergic afferents to CA1 by destruction of the CA3 region is known to protect CA1 pyramidal cells against 10 min of transient global ischemia. To investigate further the pathogenetic significance of glutamate, we measured the release of glutamate in intact and CA3-lesioned CA...

a Representation-Driven Ontology for Spatial Data Quality Elements, with Orthoimagery as Running Example

Science.gov (United States)

Hangouët, J.-F.

2015-08-01

The many facets of what is encompassed by such an expression as "quality of spatial data" can be considered as a specific domain of reality worthy of formal description, i.e. of ontological abstraction. Various ontologies for data quality elements have already been proposed in literature. Today, the system of quality elements is most generally used and discussed according to the configuration exposed in the "data dictionary for data quality" of international standard ISO 19157. Our communication proposes an alternative view. This is founded on a perspective which focuses on the specificity of spatial data as a product: the representation perspective, where data in the computer are meant to show things of the geographic world and to be interpreted as such. The resulting ontology introduces new elements, the usefulness of which will be illustrated by orthoimagery examples.

Lucky numbers: spatial neglect affects physical, but not representational, choices in a lotto task.

Science.gov (United States)

Loetscher, Tobias; Nicholls, Michael E R; Towse, John N; Bradshaw, John L; Brugger, Peter

2010-05-01

Spatial neglect can be characterized by a "magnetic attraction" towards the right side of a visual stimulus array and a selection of stimuli from that hemispace. This study examined whether these distinctive characteristics in visuo-motor space are also evident in representational number space. Given that numbers are thought to be represented along a left-to-right oriented mental number line, an affinity for the spontaneous selection of larger numbers was anticipated for neglect patients. Contrary to this expectation, neglect patients (n=20) picked a similar range of numbers compared to controls (n=17) when generating a number between 1000 and 10,000 and when playing an imaginary lottery game. There was, however, a positive correlation between the biases for the imaginary lottery, number generation and a number bisection task - demonstrating that exploration asymmetries along the mental number line are consistent within individuals across tasks. Some of the patients selected smaller numbers in all of these tasks, confirming reports of dissociations between physical and numerical-representational forms of neglect. Conversely, only four (20%) of the patients could reliably be classified as demonstrating a neglect in number space. When filling out a physical lottery ticket, the neglect patients showed the expected bias towards picking numbers placed on the right-hand side of the ticket. These results demonstrate that the magnetic attraction towards the right side of mental representations is rather weak and that representational forms of neglect only occasionally co-exist with neglect in physical space. Copyright 2009 Elsevier Srl. All rights reserved.

CaCO3-III and CaCO3-VI, high-pressure polymorphs of calcite: Possible host structures for carbon in the Earth's mantle

Science.gov (United States)

Merlini, M.; Hanfland, M.; Crichton, W. A.

2012-06-01

Calcite, CaCO3, undergoes several high pressure phase transitions. We report here the crystal structure determination of the CaCO3-III and CaCO3-VI high-pressure polymorphs obtained by single-crystal synchrotron X-ray diffraction. This new technical development at synchrotron beamlines currently affords the possibility of collecting single-crystal data suitable for structure determination in-situ at non-ambient conditions, even after multiphase transitions. CaCO3-III, observed in the pressure range 2.5-15 GPa, is triclinic, and it presents two closely related structural modifications, one, CaCO3-III, with 50 atoms in the unit cell [a=6.281(1) Å, b=7.507(2) Å, c=12.516(3) Å, α=93.76(2)°, β=98.95(2)°, γ=106.49(2)°, V=555.26(20) Å3 at 2.8 GPa], the second, CaCO3-IIIb, with 20 atoms [a=6.144(3) Å, b=6.3715(14) Å, c=6.3759(15) Å, α= 93.84(2)°, β=107.34(3)°, γ=107.16(3)°, V=224.33(13) Å3 at 3.1 GPa]. Different pressure-time experimental paths can stabilise one or the other polymorph. Both structures are characterised by the presence of non-coplanar CO3 groups. The densities of CaCO3-III (2.99 g/cm3 at 2.8 GPa) and CaCO3-IIIb (2.96 g/cm3 at 3.1 GPa) are lower than aragonite, in agreement with the currently accepted view of aragonite as the thermodynamically stable Ca-carbonate phase at these pressures. The presence of different cation sites, with variable volume and coordination number (7-9), suggests however that these structures have the potential to accommodate cations with different sizes without introducing major structural strain. Indeed, this structure can be adopted by natural Ca-rich carbonates, which often exhibit compositions deviating from pure calcite. Mg-calcites are found both in nature (Frezzotti et al., 2011) and in experimental syntheses at conditions corresponding to deep subduction environments (Poli et al., 2009). At these conditions, the low pressure rhombohedral calcite structure is most unlikely to be stable, and, at the same

Gene of the month: PIK3CA.

Science.gov (United States)

Lai, K; Killingsworth, M C; Lee, C S

2015-04-01

PIK3CA encodes the p110α catalytic subunit of phosphatidylinositol 3-kinase (PI3K) which through its role in the PI3K/Akt pathway is important for the regulation of important cellular functions such as proliferation, metabolism and protein synthesis, angiogenesis and apoptosis. Mutations in PIK3CA are known to be involved in a wide range of human cancers and mutant PIK3CA is thought to act as an oncogene. The specific PIK3CA inhibitor, NVP-BYL719, has displayed promising results in cancer therapy and is currently under clinical trials. Furthermore, PI3K regulates autophagy, a cellular process that recycles proteins and organelles through lysosomal degradation and has recently been recognised as an attractive therapeutic target due to its pro- and anti-cancer properties. Several studies have attempted to investigate the effects of combining the inhibition of both PI3K and autophagy in cancer therapy, and an in vivo model has demonstrated that the combined use of a concomitant PI3K and autophagy inhibitor induced apoptosis in glioma cells. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Low temperature synthesis of CaZrO3 nanoceramics from CaCl2–NaCl molten eutectic salt

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Rahman Fazli

2015-06-01

Full Text Available CaZrO3 nanoceramics were successfully synthesized at 700 C using the molten salt method, and the effects of processing parameters, such as temperature, holding time, and amount of salt on the crystallization of CaZrO3 were investigated. CaCl2, Na2CO3, and nano-ZrO2 were used as starting materials. On heating, CaCl2–NaCl molten eutectic salt provided a liquid medium for the reaction of CaCO3 and ZrO2 to form CaZrO3. The results demonstrated that CaZrO3 started to form at about 600C and that, after the temperature was increased to 1,000C, the amounts of CaZrO3 in the resultant powders increased with a concomitant decrease in CaCO3and ZrO2 contents. After washing with hot distilled water, the samples heated for 3 h at 700C were single-phase CaZrO3 with 90–95 nm particle size. Furthermore, the synthesized CaZrO3 particles retained the size and morphology of the ZrO2 powders which indicated that a template mechanism dominated the formation of CaZrO3 by molten-salt method.

Value of Combined Detection of Serum CEA, CA72-4, CA19-9, CA15-3 and CA12-5 in the Diagnosis of Gastric Cancer.

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Chen, Changguo; Chen, Qiuyuan; Zhao, Qiangyuan; Liu, Min; Guo, Jianwei

2017-05-01

To examine whether the combined detection of serum tumor markers (CEA, CA72-4, CA19-9, CA15-3 and CA12-5) improves the sensitivity and accuracy in the diagnosis of gastric cancer (GC). An automatic chemiluminescence immune analyzer with matched kits was used to determine the levels of serum CEA, CA72-4, CA19-9, CA15-3, and CA12-5 in 87 patients with gastric cancer (GC group), 60 patients with gastric benign diseases (GBD group) who were hospitalized during the same period, and 40 healthy subjects undergoing a physical examination. The values of these 5 tumor markers in the diagnosis of gastric cancer were analyzed. The levels of serum CEA, CA72-4, CA19-9, and CA12-5 were higher in the GC group than in the GBD group and healthy subjects, and these differences were significant ( P 0.05). The combined detection of CEA, CA72-4, CA19-9, and CA12-5 had a higher diagnostic value for gastric cancer than did single detection, and the positive detection rate of the combined detection of the four tumor markers was 60.9%. The diagnostic power when using the combined detection of CA72-4, CEA, CA19-9, and CA12-5 was the best. The combined detection of serum CA72-4, CEA, CA19-9 and CA12-5 increases the sensitivity and accuracy in the diagnosis of GC and can thus be considered an important tool for early diagnosis. © 2017 by the Association of Clinical Scientists, Inc.

Orienting attention to locations in mental representations

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Astle, Duncan Edward; Summerfield, Jennifer; Griffin, Ivan; Nobre, Anna Christina

2014-01-01

Many cognitive processes depend on our ability to hold information in mind, often well beyond the offset of the original sensory input. The capacity of this ‘visual short-term memory’ (VSTM) is limited to around three to four items. Recent research has demonstrated that the content of VSTM can be modulated by top-down attentional biases. This has been demonstrated using retrodictive spatial cues, termed ‘retro-cues’, which orient participants’ attention to spatial locations within VSTM. In the current paper, we tested whether the use of these cues is modulated by memory load and cue delay. There are a number of important conclusions: i) top-down biases can operate upon very brief iconic traces as well as older VSTM representations (Experiment 1); ii) when operating within capacity, subjects use the cue to prioritize where they initiate their memory search, rather than to discard un-cued items (Experiments 2 and 3); iii) when capacity is exceeded there is little benefit to top-down biasing relative to a neutral condition, however, unattended items are lost, with there being a substantial cost of invalid spatial cueing (Experiment 3); iv) these costs and benefits of orienting spatial attention differ across iconic memory and VSTM representations when VSTM capacity is exceeded (Experiment 4). PMID:21972046

Human neuroimaging studies on the hippocampal CA3 region – integrating evidence for pattern separation and completion

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Lorena eDeuker

2014-03-01

Full Text Available Human functional magnetic imaging (fMRI studies have long investigated the hippocampus without differentiating between its subfields, even though theoretical models and rodent studies suggest that subfields support different and potentially even opposite functions. The CA3 region of the hippocampus has been ascribed a pivotal role both in initially forming associations during encoding and in reconstructing a memory representation based on partial cues during retrieval. These functions have been related to pattern separation and pattern completion, respectively. In recent years, studies using high-resolution fMRI in humans have begun to separate different hippocampal subregions and identify the role of the CA3 subregion relative to the other subregions. However, some of these findings have been inconsistent with theoretical models and findings from electrophysiology. In this review, we describe selected recent studies and highlight how their results might help to define different processes and functions that are presumably carried out by the CA3 region, in particular regarding the seemingly opposing functions of pattern separation and pattern completion. We also describe how these subfield-specific processes are related to behavioral, functional and structural alterations in patients with mild cognitive impairment and Alzheimer’s disease. We conclude with discussing limitations of functional imaging and briefly outline possible future developments of the field.

Somal and dendritic development of human CA3 pyramidal neurons from midgestation to middle childhood: a quantitative Golgi study.

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Lu, Dahua; He, Lixin; Xiang, Wei; Ai, Wei-Min; Cao, Ye; Wang, Xiao-Sheng; Pan, Aihua; Luo, Xue-Gang; Li, Zhiyuan; Yan, Xiao-Xin

2013-01-01

The CA3 area serves a key relay on the tri-synaptic loop of the hippocampal formation which supports multiple forms of mnemonic processing, especially spatial learning and memory. To date, morphometric data about human CA3 pyramidal neurons are relatively rare, with little information available for their pre- and postnatal development. Herein, we report a set of developmental trajectory data, including somal growth, dendritic elongation and branching, and spine formation, of human CA3 pyramidal neurons from midgestation stage to middle childhood. Golgi-impregnated CA3 pyramidal neurons in fetuses at 19, 20, 26, 35, and 38 weeks of gestation (GW) and a child at 8 years of age (Y) were analyzed by Neurolucida morphometry. Somal size of the impregnated CA3 cells increased age-dependently among the cases. The length of the apical and basal dendrites of these neurons increased between 26 GW to 38 GW, and appeared to remain stable afterward until 8 Y. Dendritic branching points increased from 26 GW to 38 GW, with that on the apical dendrites slightly reduced at 8 Y. Spine density on the apical and basal dendrites increased progressively from 26 GW to 8 Y. These data suggest that somal growth and dendritic arborization of human CA3 pyramidal neurons occur largely during the second to third trimester. Spine development and likely synaptogenesis on CA3 pyramidal cells progress during the third prenatal trimester and may continue throughout childhood. Copyright © 2012 Wiley Periodicals, Inc.

Anti-tumor activity of self-charged (Eu,Ca):WO3 and Eu:CaWO4 nanoparticles

International Nuclear Information System (INIS)

Lin, Cao; Cong, Wang; De'An, Pan; Jiexin, Cao; Ping, Che; Volinsky, Alex A.

2012-01-01

Non-stoichiometric (Eu,Ca):WO 3 and Eu:CaWO 4 nanoparticles with anti-tumor activity are synthesized in a sol-gel method by adding excessive Eu 3+ and Ca 2+ ions to tungsten oxide crystal structure. Colorimetric assay shows that 10 nm (Eu,Ca):WO 3 and Eu:CaWO 4 nanoparticles can effectively inhibit growth of mammary cancer cells without any harm to normal cells. Nanoparticles are characterized by X-ray diffraction, high resolution transmission electron microscopy and fluorescence optical spectrometry. Nanomaterials, insoluble in synthesized water, have complicated self-charging surfaces that trap mammary cancer cells. Surface self-charging effect is suggested as the inhibition mechanism. (author)

Exogenous hydrogen sulfide eliminates spatial memory retrieval impairment and hippocampal CA1 LTD enhancement caused by acute stress via promoting glutamate uptake.

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He, Jin; Guo, Ruixian; Qiu, Pengxin; Su, Xingwen; Yan, Guangmei; Feng, Jianqiang

2017-05-14

Acute stress impairs the hippocampus-dependent spatial memory retrieval, and its synaptic mechanisms are associated with hippocampal CA1 long-term depression (LTD) enhancement in the adult rats. Endogenous hydrogen sulfide (H 2 S) is recognized as a novel gasotransmitter and has the neural protective roles. However, very little attention has been paid to understanding the effects of H 2 S on spatial memory retrieval impairment. We observed the protective effects of NaHS (a donor of H 2 S) against spatial memory retrieval impairment caused by acute stress and its synaptic mechanisms. Our results showed that NaHS abolished spatial memory retrieval impairment and hippocampal CA1 LTD enhancement caused by acute stress, but not by glutamate transporter inhibitor l-trans-pyrrolidine-2,4-dicarboxylic (tPDC), indicating that the activation of glutamate transporters is necessary for exogenous H 2 S to exert its roles. Moreover, NaHS restored the decreased glutamate uptake in the hippocampal CA1 synaptosomal fraction caused by acute stress. Dithiothreitol (DTT, a disulfide reducing agent) abolished a decrease in the glutamate uptake caused by acute stress, and NaHS eradicated the decreased glutamate uptake caused by 5,5'-dithio-bis(2-nitrobenzoic)acid (DTNB, a thiol oxidizing agent), collectively, revealing that exogenous H 2 S increases glutamate uptake by reducing disulfide bonds of the glutamate transporters. Additionally, NaHS inhibited the increased expression level of phosphorylated c-Jun-N-terminal kinase (JNK) in the hippocampal CA1 region caused by acute stress. The JNK inhibitor SP600125 eliminated spatial memory retrieval impairment, hippocampal CA1 LTD enhancement and the decreased glutamate uptake caused by acute stress, indicating that exogenous H 2 S exerts these roles by inhibiting the activation of JNK signaling pathway. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Dynamic representation of 3D auditory space in the midbrain of the free-flying echolocating bat

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2018-01-01

Essential to spatial orientation in the natural environment is a dynamic representation of direction and distance to objects. Despite the importance of 3D spatial localization to parse objects in the environment and to guide movement, most neurophysiological investigations of sensory mapping have been limited to studies of restrained subjects, tested with 2D, artificial stimuli. Here, we show for the first time that sensory neurons in the midbrain superior colliculus (SC) of the free-flying echolocating bat encode 3D egocentric space, and that the bat’s inspection of objects in the physical environment sharpens tuning of single neurons, and shifts peak responses to represent closer distances. These findings emerged from wireless neural recordings in free-flying bats, in combination with an echo model that computes the animal’s instantaneous stimulus space. Our research reveals dynamic 3D space coding in a freely moving mammal engaged in a real-world navigation task. PMID:29633711

Observation of microstructure of hydrated Ca3SiO5

International Nuclear Information System (INIS)

Mori, Kazuhiro; Sato, Takashi; Fukunaga, Toshiharu; Oishi, Koji; Kimura, Katsuhiko; Iwase, Kenji; Sugiyama, Masaaki; Itoh, Keiji; Shikanai, Fumihito; Wuernisha, Tuerxun; Yonemura, Masao; Sulistyanintyas, Dyah; Tsukushi, Itaru; Takata, Shinich; Otomo, Toshiya; Kamiyma, Takashi; Kawai, Masayoshi

2006-01-01

Quasi-elastic neutron scattering experiments were carried out to evaluate the hydration rate of tricalcium silicate (Ca 3 SiO 5 ). Furthermore, in the early hydration period, a variation in surface roughness of Ca 3 SiO 5 was observed in nano-scale by the small-angle neutron scattering. From these results, it was found that the hydration rate of Ca 3 SiO 5 is suppressed when the surface of Ca 3 SiO 5 becomes rough through the creation of hydration products C-S-H gel and Ca(OH) 2 , and this roughness is associated with changes in the Ca 3 SiO 5 hydration rate

The diagnostic value of serum tumor markers CEA, CA19-9, CA125, CA15-3, and TPS in metastatic breast cancer.

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Wang, Weigang; Xu, Xiaoqin; Tian, Baoguo; Wang, Yan; Du, Lili; Sun, Ting; Shi, Yanchun; Zhao, Xianwen; Jing, Jiexian

2017-07-01

This study aims to understand the diagnostic value of serum tumor markers carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), cancer antigen 125 (CA125), cancer antigen 15-3 (CA15-3), and tissue polypeptide-specific antigen (TPS) in metastatic breast cancer (MBC). A total of 164 metastatic breast cancer patients in Shanxi Cancer Hospital were recruited between February 2016 and July 2016. 200 breast cancer patients without metastasis in the same period were randomly selected as the control group. The general characteristics, immunohistochemical, and pathological results were investigated between the two groups, and tumor markers were determined. There were statistical differences in the concentration and the positive rates of CEA, CA19-9, CA125, CA15-3, and TPS between the MBC and control group (Ptumor marker at 56.7% and 97.0%, respectively. In addition, two tumor markers were used for the diagnosis of MBC and the CEA and TPS combination had the highest diagnostic sensitivity with 78.7%, while the CA15-3 and CA125 combination had the highest specificity of 91.5%. Analysis of tumor markers of 164 MBC found that there were statistical differences in the positive rates of CEA and CA15-3 between bone metastases and other metastases (χ 2 =6.00, P=0.014; χ 2 =7.32, P=0.007, respectively). The sensitivity and specificity values of the CEA and CA15-3 combination in the diagnosis of bone metastases were 77.1% and 45.8%, respectively. The positive rate of TPS in the lung metastases group was lower than in other metastases (χ 2 =8.06, P=0.005).There were significant differences in the positive rates of CA15-3 and TPS between liver metastases and other metastases (χ 2 =15.42, Ptumor markers have varying diagnostic value. Copyright © 2017 Elsevier B.V. All rights reserved.

Linear optical properties of Ca4EuO(BO3)3 and Eu3+ : Ca4GdO(BO3)3 crystals

International Nuclear Information System (INIS)

Antic-Fidancev, E.; Lemaitre-Blaise, M.; Porcher, P.; Caramanian, A.; Aka, G.

1998-01-01

Full text: The title compounds are now intensively studied due to their quadratic nonlinear properties in view of applications, e.g. high power laser frequency conversion. Rare earth calcium oxoborates, Ca 4 REO(BO 3 ) 3 , constitute an isostructural family along the rare earth series with RE = La - Lu, Y included. These compounds crystallize in the monoclinic biaxial crystal system with Cm (N 8) space group. They are isostructural to the calcium fluoroborate Ca 5 (BO 3 ) 3 F which is related to the fluoroapatite structure Ca 5 (PO 4 ) 3 F. The rare earth ions are located in the distorted octahedron with C s point site symmetry in the mirror plane. Two types of distorted octahedral sites exist for calcium ions. The existence of some disorder between calcium and rare earth atoms is suspected from the structural analysis. Good optical quality crystals of europium (or gadolinium) oxoborate, EuCOB (GdCOB) have been grown from the stoichiometric melt by the Czochralski pulling method. From the luminescence of the Eu 3+ doped gadolinium or in the europium stoichiometric compound very complex emission spectra have been obtained. It principally depends on the preparation method of studied samples: i) for a monocrystalline sample, a single phase with a single site is observed; ii) for a polycrystalline sample complex feature occurs. It is probably due to an expanded disorder between calcium and rare earth atoms. Practically, there is one principal site corresponding to the low symmetry site of the rare earth as expected from the structural investigation. Other minor sites are attributed to the local distortion created around the active rare earth ion. The intensity of the emission lines of Eu 3+ used as a local structural probe related to these minor sites increases when the gadolinium in Ca 4 GdO(BO 0 ) 3 is substituted by lanthanum or yttrium ions. It seems therefore evident that the synthesis of these rare earth calcium oxoborates must be realised carefully. The crystal

FGFR3, PIK3CA and RAS mutations in benign lichenoid keratosis.

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Groesser, L; Herschberger, E; Landthaler, M; Hafner, C

2012-04-01

Benign lichenoid keratoses (BLKs) are solitary skin lesions which have been proposed to represent a regressive form of pre-existent epidermal tumours such as solar lentigo or seborrhoeic keratosis. However, the genetic basis of BLK is unknown. FGFR3, PIK3CA and RAS mutations have been shown to be involved in the pathogenesis of seborrhoeic keratosis and solar lentigo. We thus investigated whether these mutations are also present in BLK. After manual microdissection and DNA isolation, 52 BLKs were screened for FGFR3, PIK3CA and RAS hotspot mutations using SNaPshot(®) multiplex assays. We identified 6/52 (12%) FGFR3 mutations, 10/52 (19%) PIK3CA mutations, 6/52 (12%) HRAS mutations and 2/52 (4%) KRAS mutations. FGFR3 and RAS mutations were mutually exclusive. One BLK showed a simultaneous PIK3CA and HRAS mutation. In nine BLKs with a mutation, nonlesional control tissue from the epidermal margin and the dermal lymphocytic infiltrate were wild-type, indicating that these mutations are somatic. To demonstrate that these findings are specific, 10 samples of lichen planus were analysed without evidence for FGFR3, PIK3CA or RAS mutations. Our results indicate that FGFR3, PIK3CA and RAS mutations are present in approximately 50% of BLKs. These findings support the concept on the molecular genetic level that at least a proportion of BLKs represents regressive variants resulting from former benign epidermal tumours such as seborrhoeic keratosis and solar lentigo. © 2011 The Authors. BJD © 2011 British Association of Dermatologists 2011.

Enhanced magnetoresistance in La0.7Ca0.3Mn03/Nd0.7Ca0.3Mn03 epitaxial multilayers

International Nuclear Information System (INIS)

Sharma, Himanshu; Khan, Md. S.; Tomy, C.V.; Jain, Sourabh; Tulapurkar, Ashwin

2014-01-01

Magnanite multilayers of La 0.7 Ca 0.3 MnO 3 /Nd 0.7 Ca 0.5 MnO 3 have been fabricated on SrTiO 3 (100) substrate using Nd 0.7 Ca 0.5 MnO 3 as the spacer layers. An enhanced magnetoresistance (MR) of more than 80% is observed in the multilayers compared with LCMO thin film (∼50%). Result suggests that the interface strains between LCMO and NCMO layers may have influences on the transport properties and a suitable film structure could be used to increase the large low field magnetoresistance. (author)

Intransigent Vowel-Consonant Position in Korean Dysgraphia: Evidence of Spatial-Constructive Representation

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HyangHee Kim

2007-01-01

Full Text Available Dysgraphia due to a focal brain lesion can be characterized by substitution, transposition, deletion and/or addition errors of graphemes or strokes. However, those linguistic errors can be language-specific because the writing system of a given language may influence error patterns. We investigated a Korean stroke patient, a 57-year-old English teacher with dysgraphia both in Korean Han-geul (한글 and in English alphabet writings. The results of an experimental testing revealed transposition errors between a consonant and a vowel only in English but not in Korean writings. This austerity of vowel-consonant position may be attributed to a unique Korean writing system of a spatially well-formed syllabic configuration or block with consonant(s and a vowel. In light of a neuropsychological model of writing, which depicts a multi-level spelling and writing process, we suggest a spatial-constructional component of internal orthographic representations in Korean writing. This Korean graphemic configuration feature may be resistant to a focal, left cerebral damage, and thus, we also discuss our results in terms of cerebral lateralization of the writing processes.

Spatial displacement of numbers on a vertical number line in spatial neglect

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Urszula eMihulowicz

2015-04-01

Full Text Available Previous studies that investigated the association of numbers and space in humans came to contradictory conclusions about the spatial character of the mental number magnitude representation and about how it may be influenced by unilateral spatial neglect. The present study aimed to disentangle the debated influence of perceptual versus representational aspects via explicit mapping of numbers onto space by applying the number line estimation paradigm with vertical orientation of stimulus lines. Thirty-five acute right-brain damaged stroke patients (6 with neglect were asked to place two-digit numbers on vertically oriented lines with 0 marked at the bottom and 100 at the top. In contrast to the expected, nearly linear mapping in the control patient group, patients with spatial neglect overestimated the position of numbers in the lower middle range. The results corroborate spatial characteristics of the number magnitude representation. In neglect patients, this representation seems to be biased towards the ipsilesional side, independent of the physical orientation of the task stimuli.

Activity of RE/sub 2/O/sub 3/ in liquid La/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-CaF/sub 2/ and Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slags

International Nuclear Information System (INIS)

Changzhen, W.; Shuqing, Y.; Qieng, D.

1985-01-01

In the course of electro-slag refining, if the slag contains rare earth oxides, the amount of rare earth introduced to the steel depends on the composition of the slag and other conditions. The main aim of this investigation is to study the activity of RE/sub 2/O/sub 3/ in the electro-slags of various compositions. One is the La/sub 2/O/sub 3/-CaO-CaF/sub 2/ ternary slag system and the other is the Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slag system. The iso-activity diagram for RE/sub 2/O/sub 3/ and the liquid boundary for slags system were estimated

Application package DeCA. Version 3.3

International Nuclear Information System (INIS)

Gladkikh, P.I.; Strelkov, M.A.; Zelinskij, A.Yu.

1993-01-01

The application package DeCA (Design of Cyclic Accelerators) is intended for solving a wide range of problems related to the dynamics of charged particle beams in cyclic accelerators and storage rings. It can be used for both design or modification purposes and numerical experimentation. The package DeCA consist of several program blocks, which are unified by functional principle. In this article we are consider the description of two blocks: the control block (COMM), and the description of magnetic elements and lattices block (IMOS). The formats of package commands, language of lattice definition and list of own commands of these blocks are described. (author). 4 refs., 3 ape

Reference frames for spatial frequency in face representation differ in the temporal visual cortex and amygdala.

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Inagaki, Mikio; Fujita, Ichiro

2011-07-13

Social communication in nonhuman primates and humans is strongly affected by facial information from other individuals. Many cortical and subcortical brain areas are known to be involved in processing facial information. However, how the neural representation of faces differs across different brain areas remains unclear. Here, we demonstrate that the reference frame for spatial frequency (SF) tuning of face-responsive neurons differs in the temporal visual cortex and amygdala in monkeys. Consistent with psychophysical properties for face recognition, temporal cortex neurons were tuned to image-based SFs (cycles/image) and showed viewing distance-invariant representation of face patterns. On the other hand, many amygdala neurons were influenced by retina-based SFs (cycles/degree), a characteristic that is useful for social distance computation. The two brain areas also differed in the luminance contrast sensitivity of face-responsive neurons; amygdala neurons sharply reduced their responses to low luminance contrast images, while temporal cortex neurons maintained the level of their responses. From these results, we conclude that different types of visual processing in the temporal visual cortex and the amygdala contribute to the construction of the neural representations of faces.

CaV1.3 L-type Ca2+ channels modulate depression-like behaviour in mice independent of deaf phenotype.

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Busquet, Perrine; Nguyen, Ngoc Khoi; Schmid, Eduard; Tanimoto, Naoyuki; Seeliger, Mathias W; Ben-Yosef, Tamar; Mizuno, Fengxia; Akopian, Abram; Striessnig, Jörg; Singewald, Nicolas

2010-05-01

Mounting evidence suggests that voltage-gated L-type Ca2+ channels can modulate affective behaviour. We therefore explored the role of CaV1.3 L-type Ca2+ channels in depression- and anxiety-like behaviours using CaV1.3-deficient mice (CaV1.3-/-). We showed that CaV1.3-/- mice displayed less immobility in the forced swim test as well as in the tail suspension test, indicating an antidepressant-like phenotype. Locomotor activity in the home cage or a novel open-field test was not influenced. In the elevated plus maze (EPM), CaV1.3-/- mice entered the open arms more frequently and spent more time there indicating an anxiolytic-like phenotype which was, however, not supported in the stress-induced hyperthermia test. By performing parallel experiments in Claudin 14 knockout mice (Cldn14-/-), which like CaV1.3-/- mice are congenitally deaf, an influence of deafness on the antidepressant-like phenotype could be ruled out. On the other hand, a similar EPM behaviour indicative of an anxiolytic phenotype was also found in the Cldn14-/- animals. Using electroretinography and visual behavioural tasks we demonstrated that at least in mice, CaV1.3 channels do not significantly contribute to visual function. However, marked morphological changes were revealed in synaptic ribbons in the outer plexiform layer of CaV1.3-/- retinas by immunohistochemistry suggesting a possible role of this channel type in structural plasticity at the ribbon synapse. Taken together, our findings indicate that CaV1.3 L-type Ca2+ channels modulate depression-like behaviour but are not essential for visual function. The findings raise the possibility that selective modulation of CaV1.3 channels could be a promising new therapeutic concept for the treatment of mood disorders.

Mechanical and thermal-expansion characteristics of Ca10(PO46(OH2-Ca3(PO42 composites

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Ruseska G.

2006-01-01

Full Text Available Three types of composites consisting of Ca10(PO46(OH2 and Ca3(PO42 with composition: 75% (wt Ca10(PO46(OH2: 25%(wt Ca3(PO42; 50%(wt Ca10(PO46(OH2: 50%(wtCa3(PO42 and 25 %(wt Ca10(PO46(OH2: 75%(wt Ca3(PO42 were the subject of our investigation. Sintered compacts were in thermal equilibrium, which was proved by the absence of hysteresis effect of the dependence ΔL/L=f(T during heating /cooling in the temperature interval 20-1000-200C. Sintered compacts with the previously mentioned composition possess 26-50% higher values of the E-modulus, G-modulus and K-modulus indicating the presence of a synergism effect. Several proposed model equations for predicting the thermal expansion coefficient in dependence of the thermal and elastic properties of the constitutive phases and their volume fractions, given by: Turner, Kerner, Tummala and Friedberg, Thomas and Taya, were used for making correlations between mechanical and thermal-expansion characteristics of the Ca10(PO46(OH2 - Ca3(PO42 composites. Application of the previously mentioned model equations to all kinds of composites leads to the conclusion that the experimentally obtained results for the thermal expansion coefficient are in an excellent agreement with the theoretical calculated values on account of the volume fraction of each constitutive phase and with all applied model equations, with a coefficient of correlation from 98.16-99.86 %.

Think Spatial: The Representation in Mental Rotation Is Nonvisual

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Liesefeld, Heinrich R.; Zimmer, Hubert D.

2013-01-01

For mental rotation, introspection, theories, and interpretations of experimental results imply a certain type of mental representation, namely, visual mental images. Characteristics of the rotated representation can be examined by measuring the influence of stimulus characteristics on rotational speed. If the amount of a given type of information…

The Spatial and the Visual in Mental Spatial Reasoning: An Ill-Posed Distinction

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Schultheis, Holger; Bertel, Sven; Barkowsky, Thomas; Seifert, Inessa

It is an ongoing and controversial debate in cognitive science which aspects of knowledge humans process visually and which ones they process spatially. Similarly, artificial intelligence (AI) and cognitive science research, in building computational cognitive systems, tended to use strictly spatial or strictly visual representations. The resulting systems, however, were suboptimal both with respect to computational efficiency and cognitive plau sibility. In this paper, we propose that the problems in both research strands stem from a mis conception of the visual and the spatial in mental spatial knowl edge pro cessing. Instead of viewing the visual and the spatial as two clearly separable categories, they should be conceptualized as the extremes of a con tinuous dimension of representation. Regarding psychology, a continuous di mension avoids the need to exclusively assign processes and representations to either one of the cate gories and, thus, facilitates a more unambiguous rating of processes and rep resentations. Regarding AI and cognitive science, the con cept of a continuous spatial / visual dimension provides the possibility of rep re sentation structures which can vary continuously along the spatial / visual di mension. As a first step in exploiting these potential advantages of the pro posed conception we (a) introduce criteria allowing for a non-dichotomic judgment of processes and representations and (b) present an approach towards rep re sentation structures that can flexibly vary along the spatial / visual dimension.

Imidacloprid toxicity impairs spatial memory of echolocation bats through neural apoptosis in hippocampal CA1 and medial entorhinal cortex areas.

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Hsiao, Chun-Jen; Lin, Ching-Lung; Lin, Tian-Yu; Wang, Sheue-Er; Wu, Chung-Hsin

2016-04-13

It has been reported that the decimation of honey bees was because of pesticides of imidacloprid. The imidacloprid is a wildly used neonicotinoid insecticide. However, whether imidacloprid toxicity interferes with the spatial memory of echolocation bats is still unclear. Thus, we compared the spatial memory of Formosan leaf-nosed bats, Hipposideros terasensis, before and after chronic treatment with a low dose of imidacloprid. We observed that stereotyped flight patterns of echolocation bats that received chronic imidacloprid treatment were quite different from their originally learned paths. We further found that neural apoptosis in hippocampal CA1 and medial entorhinal cortex areas of echolocation bats that received imidacloprid treatment was significantly enhanced in comparison with echolocation bats that received sham treatment. Thus, we suggest that imidacloprid toxicity may interfere with the spatial memory of echolocation bats through neural apoptosis in hippocampal CA1 and medial entorhinal cortex areas. The results provide direct evidence that pesticide toxicity causes a spatial memory disorder in echolocation bats. This implies that agricultural pesticides may pose severe threats to the survival of echolocation bats.

Comparison of CA15-3 and CEA in breast cancer

International Nuclear Information System (INIS)

Rajkovaca, Z.; Mijatovic, J.; Matavulj, A.; Kovacevic, P.; Ponorac, N.

2002-01-01

Aim: Tumor markers are potentially powerful means for obtaining information about cancers whilst causing minimal morbidity, inconvenience and cost. CA 15-3 and CEA are considered useful tumor markers in monitoring breast cancer patients. The aim of this study was to evaluate which of these two markers are in better correlate with the disease in patients surgically treated for breast cancer. Material and Methods: We retrospectively reviewed values of CA15-3 and CEA in 342 patients (median age 52.18 years, range 27-78 years) with surgically treated and pathologically proven breast cancer. CA15-3 and CEA was measured by radioimmunoassay. CA15-3 levels above 30 U/ml and CEA levels above 5 ng/ml were considered as positive values. Results: Out of 342 patients, 86 had elevated CA15-3 levels (sensitivity: 25.1%) and 68 of 342 patients had positive CEA levels (sensitivity 19.9%). Two hundred thirty seven (237) of the patients suffering from breast cancer (69.3%) did not have metastatic disease. In this group CA15-3 sensitivity was 94.5%, while CEA sensitivity was 87.3%. One hundred and five (105) patients (30.7%) had metastatic disease. In this group, CA15-3 sensitivity was 69.5% and CEA sensitivity was 36.2% (P < 0.05). With regard to the correlation of the two tumor markers with clinical course patients had significantly higher levels of CA15-3 than of CEA in metastatic breast cancer. Conclusion: This result suggests CA15-3 to be the more sensitive and more specific of the two tumor markers for metastatic breast cancer detection and monitoring

High pressure study of low compressibility tetracalcium aluminum carbonate hydrates 3CaO·Al2O3·CaCO3·11H2O

KAUST Repository

Moon, Juhyuk; Oh, Jae Eun; Balonis, Magdalena; Glasser, Fredrik P.; Clark, Simon M.; Monteiro, Paulo J.M.

2012-01-01

Synchrotron X-ray diffraction data was collected from a sample of monocarboaluminate 3CaO•Al2O3•CaCO 3•11H2O from ambient pressure to 4.3 GPa. The refined crystal structure at ambient pressure is triclinic with parameters a = 5.77(2) Å, b = 8

Systems of Ba(PO3)2-Sr(Pu3)2, Cd(PO3)2-Ca(PO3)2

International Nuclear Information System (INIS)

Tokman, I.A.; Bukhalova, G.A.

1977-01-01

Phase diagrams of the Ba(PO 3 ) 2 -Sr(PO 3 ) 2 and Cd(PO 3 ) 2 -Ca(PO 3 ) 2 systems have been studied and plotted by the methods of differential-thermal analysis (DTA), visual-polythermal, X-ray phase and infrared spectroscopy. The Ba(PO 3 ) 2 -Sr(PO 3 ) 2 system is of the eutectic type. In the binary system Cd(PO 3 ) 2 -Ca(PO 3 ) 2 the existence of a continuous series of solid solutions with a minimum at 858 deg C and 27.5 mol.% Ca(PO 3 ) 2 has been established

Spatiotemporal representation of cardiac vectorcardiogram (VCG signals

Directory of Open Access Journals (Sweden)

Yang Hui

2012-03-01

Full Text Available Abstract Background Vectorcardiogram (VCG signals monitor both spatial and temporal cardiac electrical activities along three orthogonal planes of the body. However, the absence of spatiotemporal resolution in conventional VCG representations is a major impediment for medical interpretation and clinical usage of VCG. This is especially so because time-domain features of 12-lead ECG, instead of both spatial and temporal characteristics of VCG, are widely used for the automatic assessment of cardiac pathological patterns. Materials and methods We present a novel representation approach that captures critical spatiotemporal heart dynamics by displaying the real time motion of VCG cardiac vectors in a 3D space. Such a dynamic display can also be realized with only one lead ECG signal (e.g., ambulatory ECG through an alternative lag-reconstructed ECG representation from nonlinear dynamics principles. Furthermore, the trajectories are color coded with additional dynamical properties of space-time VCG signals, e.g., the curvature, speed, octant and phase angles to enhance the information visibility. Results In this investigation, spatiotemporal VCG signal representation is used to characterize various spatiotemporal pathological patterns for healthy control (HC, myocardial infarction (MI, atrial fibrillation (AF and bundle branch block (BBB. The proposed color coding scheme revealed that the spatial locations of the peak of T waves are in the Octant 6 for the majority (i.e., 74 out of 80 of healthy recordings in the PhysioNet PTB database. In contrast, the peak of T waves from 31.79% (117/368 of MI subjects are found to remain in Octant 6 and the rest (68.21% spread over all other octants. The spatiotemporal VCG signal representation is shown to capture the same important heart characteristics as the 12-lead ECG plots and more. Conclusions Spatiotemporal VCG signal representation is shown to facilitate the characterization of space-time cardiac

Spatial Associations and Chemical Composition of Organic Carbon Sequestered in Fe, Ca, and Organic Carbon Ternary Systems.

Science.gov (United States)

Sowers, Tyler D; Adhikari, Dinesh; Wang, Jian; Yang, Yu; Sparks, Donald L

2018-05-25

Organo-mineral associations of organic carbon (OC) with iron (Fe) oxides play a major role in environmental OC sequestration, a process crucial to mitigating climate change. Calcium has been found to have high coassociation with OC in soils containing high Fe content, increase OC sorption extent to poorly crystalline Fe oxides, and has long been suspected to form bridging complexes with Fe and OC. Due to the growing realization that Ca may be an important component of C cycling, we launched a scanning transmission X-ray microscopy (STXM) investigation, paired with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, in order to spatially resolve Fe, Ca, and OC relationships and probe the effect of Ca on sorbed OC speciation. We performed STXM-NEXAFS analysis on 2-line ferrihydrite reacted with leaf litter-extractable dissolved OC and citric acid in the absence and presence of Ca. Organic carbon was found to highly associate with Ca ( R 2 = 0.91). Carboxylic acid moieties were dominantly sequestered; however, Ca facilitated the additional sequestration of aromatic and phenolic moieties. Also, C NEXAFS revealed polyvalent metal ion complexation. Our results provide evidence for the presence of Fe-Ca-OC ternary complexation, which has the potential to significantly impact how organo-mineral associations are modeled.

Elementary properties of CaV1.3 Ca2+ channels expressed in mouse cochlear inner hair cells

Science.gov (United States)

Zampini, Valeria; Johnson, Stuart L; Franz, Christoph; Lawrence, Neil D; Münkner, Stefan; Engel, Jutta; Knipper, Marlies; Magistretti, Jacopo; Masetto, Sergio; Marcotti, Walter

2010-01-01

Mammalian cochlear inner hair cells (IHCs) are specialized to process developmental signals during immature stages and sound stimuli in adult animals. These signals are conveyed onto auditory afferent nerve fibres. Neurotransmitter release at IHC ribbon synapses is controlled by L-type CaV1.3 Ca2+ channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca2+ channels in immature mouse IHCs under near-physiological recording conditions. CaV1.3 Ca2+ channels at the cell pre-synaptic site co-localize with about half of the total number of ribbons present in immature IHCs. These channels activated at about −70 mV, showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca2+ action potential activity characteristic of these immature cells. The CaV1.3 Ca2+ channels showed a very low open probability (about 0.15 at −20 mV: near the peak of an action potential). Comparison of elementary and macroscopic Ca2+ currents indicated that very few Ca2+ channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca2+ channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca2+ channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres. PMID:19917569

Elementary properties of CaV1.3 Ca(2+) channels expressed in mouse cochlear inner hair cells.

Science.gov (United States)

Zampini, Valeria; Johnson, Stuart L; Franz, Christoph; Lawrence, Neil D; Münkner, Stefan; Engel, Jutta; Knipper, Marlies; Magistretti, Jacopo; Masetto, Sergio; Marcotti, Walter

2010-01-01

Mammalian cochlear inner hair cells (IHCs) are specialized to process developmental signals during immature stages and sound stimuli in adult animals. These signals are conveyed onto auditory afferent nerve fibres. Neurotransmitter release at IHC ribbon synapses is controlled by L-type Ca(V)1.3 Ca(2+) channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca(2+) channels in immature mouse IHCs under near-physiological recording conditions. Ca(V)1.3 Ca(2+) channels at the cell pre-synaptic site co-localize with about half of the total number of ribbons present in immature IHCs. These channels activated at about 70 mV, showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca(2+) action potential activity characteristic of these immature cells. The Ca(V)1.3 Ca(2+) channels showed a very low open probability (about 0.15 at 20 mV: near the peak of an action potential). Comparison of elementary and macroscopic Ca(2+) currents indicated that very few Ca(2+) channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca(2+) channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca(2+) channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.

Vibrational spectroscopic study of poldervaartite CaCa[SiO3(OH)(OH)

Science.gov (United States)

Frost, Ray L.; López, Andrés; Scholz, Ricardo; Lima, Rosa Malena Fernandes

2015-02-01

We have studied the mineral poldervaartite CaCa[SiO3(OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 °C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite.

Altered thalamocortical rhythmicity and connectivity in mice lacking CaV3.1 T-type Ca2+ channels in unconsciousness

Science.gov (United States)

Choi, Soonwook; Yu, Eunah; Lee, Seongwon; Llinás, Rodolfo R.

2015-01-01

In unconscious status (e.g., deep sleep and anesthetic unconsciousness) where cognitive functions are not generated there is still a significant level of brain activity present. Indeed, the electrophysiology of the unconscious brain is characterized by well-defined thalamocortical rhythmicity. Here we address the ionic basis for such thalamocortical rhythms during unconsciousness. In particular, we address the role of CaV3.1 T-type Ca2+ channels, which are richly expressed in thalamic neurons. Toward this aim, we examined the electrophysiological and behavioral phenotypes of mice lacking CaV3.1 channels (CaV3.1 knockout) during unconsciousness induced by ketamine or ethanol administration. Our findings indicate that CaV3.1 KO mice displayed attenuated low-frequency oscillations in thalamocortical loops, especially in the 1- to 4-Hz delta band, compared with control mice (CaV3.1 WT). Intriguingly, we also found that CaV3.1 KO mice exhibited augmented high-frequency oscillations during unconsciousness. In a behavioral measure of unconsciousness dynamics, CaV3.1 KO mice took longer to fall into the unconscious state than controls. In addition, such unconscious events had a shorter duration than those of control mice. The thalamocortical interaction level between mediodorsal thalamus and frontal cortex in CaV3.1 KO mice was significantly lower, especially for delta band oscillations, compared with that of CaV3.1 WT mice, during unconsciousness. These results suggest that the CaV3.1 channel is required for the generation of a given set of thalamocortical rhythms during unconsciousness. Further, that thalamocortical resonant neuronal activity supported by this channel is important for the control of vigilance states. PMID:26056284

Acute effects of alcohol on intrusive memory development and viewpoint dependence in spatial memory support a dual representation model.

Science.gov (United States)

Bisby, James A; King, John A; Brewin, Chris R; Burgess, Neil; Curran, H Valerie

2010-08-01

A dual representation model of intrusive memory proposes that personally experienced events give rise to two types of representation: an image-based, egocentric representation based on sensory-perceptual features; and a more abstract, allocentric representation that incorporates spatiotemporal context. The model proposes that intrusions reflect involuntary reactivation of egocentric representations in the absence of a corresponding allocentric representation. We tested the model by investigating the effect of alcohol on intrusive memories and, concurrently, on egocentric and allocentric spatial memory. With a double-blind independent group design participants were administered alcohol (.4 or .8 g/kg) or placebo. A virtual environment was used to present objects and test recognition memory from the same viewpoint as presentation (tapping egocentric memory) or a shifted viewpoint (tapping allocentric memory). Participants were also exposed to a trauma video and required to detail intrusive memories for 7 days, after which explicit memory was assessed. There was a selective impairment of shifted-view recognition after the low dose of alcohol, whereas the high dose induced a global impairment in same-view and shifted-view conditions. Alcohol showed a dose-dependent inverted "U"-shaped effect on intrusions, with only the low dose increasing the number of intrusions, replicating previous work. When same-view recognition was intact, decrements in shifted-view recognition were associated with increases in intrusions. The differential effect of alcohol on intrusive memories and on same/shifted-view recognition support a dual representation model in which intrusions might reflect an imbalance between two types of memory representation. These findings highlight important clinical implications, given alcohol's involvement in real-life trauma. Copyright 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Long-lasting spatial learning and memory impairments caused by chronic cerebral hypoperfusion associate with a dynamic change of HCN1/HCN2 expression in hippocampal CA1 region.

Science.gov (United States)

Luo, Pan; Lu, Yun; Li, Changjun; Zhou, Mei; Chen, Cheng; Lu, Qing; Xu, Xulin; He, Zhi; Guo, Lianjun

2015-09-01

Chronic cerebral hypoperfusion (CCH) causes learning and memory impairments and increases the risk of Alzheimer disease (AD) and vascular dementia (VD) through several biologically plausible pathways, yet the mechanisms underlying the disease process remained unclear particularly in a temporal manner. We performed permanent bilateral occlusion of the common carotid arteries (two-vessel occlusion, 2VO) to induce CCH. To determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are altered at different stages of cognitive impairment caused by CCH, adult male SD rats were randomly distributed into sham-operated 4, 8 and 12weeks group, 2VO 4, 8 and 12weeks group. Learning and memory performance were evaluated with Morris water maze (MWM) and long-term potentiation (LTP) was used to address the underlying synaptic mechanisms. Expression of NeuN, HCN1 and HCN2 in hippocampal CA1, DG and CA3 areas was quantified by immunohistochemistry and western blotting. Our data showed that CCH induced a remarkable spatial learning and memory deficits in rats of 2VO 4, 8, and 12weeks group although neuronal loss only occurred after 4weeks of 2VO surgery in CA1. In addition, a significant reduction of HCN1 surface expression in CA1 was observed in the group that suffered 4weeks ischemia but neither 8 nor 12weeks. However, HCN2 surface expression in CA1 increased throughout the ischemia time-scales (4, 8 and 12w). Our findings indicate spatial learning and memory deficits in the CCH model are associated with disturbed HCN1 and HCN2 surface expression in hippocampal CA1. The altered patterns of both HCN1 and HCN2 surface expression may be implicated in the early stage (4w) of spatial learning and memory impairments; and the stable and long-lasting impairments of spatial learning and memory may partially attribute to the up-regulated HCN2 surface expression. Copyright © 2015 Elsevier Inc. All rights reserved.

CaMKII-dependent dendrite ramification and spine generation promote spatial training-induced memory improvement in a rat model of sporadic Alzheimer's disease.

Science.gov (United States)

Jiang, Xia; Chai, Gao-Shang; Wang, Zhi-Hao; Hu, Yu; Li, Xiao-Guang; Ma, Zhi-Wei; Wang, Qun; Wang, Jian-Zhi; Liu, Gong-Ping

2015-02-01

Participation in cognitively stimulating activities can preserve memory capacities in patients with Alzheimer's disease (AD), but the mechanism is not fully understood. Here, we used a rat model with hyperhomocysteinemia, an independent risk factor of AD, to study whether spatial training could remodel the synaptic and/or dendritic plasticity and the key molecular target(s) involved. We found that spatial training in water maze remarkably improved the subsequent short-term and long-term memory performance in contextual fear conditioning and Barnes maze. The trained rats showed an enhanced dendrite ramification, spine generation and plasticity in dentate gyrus (DG) neurons, and stimulation of long-term potentiation between perforant path and DG circuit. Spatial training also increased the levels of postsynaptic GluA1, GluN2A, GluN2B, and PSD93 with selective activation of calcium/calmodulin-dependent protein kinase II (CaMKII), although inhibition of CaMKII by stereotaxic injection of KN93 into hippocampal DG, abolished the training-induced cognitive improvement, dendrite ramification, and spine generation. We conclude that spatial training can preserve the cognitive function by CaMKII-dependent remodeling of dendritic plasticity in hyperhomocysteinemia-induced sporadic AD-like rats. Copyright © 2015 Elsevier Inc. All rights reserved.

Partition function of free conformal fields in 3-plet representation

Energy Technology Data Exchange (ETDEWEB)

Beccaria, Matteo [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento & INFN,Via Arnesano, 73100 Lecce (Italy); Tseytlin, Arkady A. [The Blackett Laboratory, Imperial College,London SW7 2AZ (United Kingdom)

2017-05-10

Simplest examples of AdS/CFT duality correspond to free CFTs in d dimensions with fields in vector or adjoint representation of an internal symmetry group dual in the large N limit to a theory of massless or massless plus massive higher spins in AdS{sub d+1}. One may also study generalizations when conformal fields belong to higher dimensional representations, i.e. carry more than two internal symmetry indices. Here we consider the case of the 3-fundamental (“3-plet”) representation. One motivation is a conjectured connection to multiple M5-brane theory: heuristic arguments suggest that it may be related to an (interacting) CFT of 6d (2,0) tensor multiplets in 3-plet representation of large N symmetry group that has an AdS{sub 7} dual. We compute the singlet partition function Z on S{sup 1}×S{sup d−1} for a free field in 3-plet representation of U(N) and analyse its novel large N behaviour. The large N limit of the low temperature expansion of Z which is convergent in the vector and adjoint cases here is only asymptotic, reflecting the much faster growth of the number of singlet operators with dimension, indicating a phase transition at very low temperature. Indeed, while the critical temperatures in the vector (T{sub c}∼N{sup γ}, γ>0) and adjoint (T{sub c}∼1) cases are finite, we find that in the 3-plet case T{sub c}∼(log N){sup −1}, i.e. it approaches zero at large N. We discuss some details of large N solution for the eigenvalue distribution. Similar conclusions apply to higher p-plet representations of U(N) or O(N) and also to the free p-tensor theories invariant under [U(N)]{sup p} or [O(N)]{sup p} with p≥3.

Strong coupling and quasispinor representations of the SU(3) rotor model

International Nuclear Information System (INIS)

Rowe, D.J.; De Guise, H.

1992-01-01

We define a coupling scheme, in close parallel to the coupling scheme of Elliott and Wilsdon, in which nucleonic intrinsic spins are strongly coupled to SU(3) spatial wave functions. The scheme is proposed for shell-model calculations in strongly deformed nuclei and for semimicroscopic analyses of rotations in odd-mass nuclei and other nuclei for which the spin-orbit interaction is believed to play an important role. The coupling scheme extends the domain of utility of the SU(3) model, and the symplectic model, to heavy nuclei and odd-mass nuclei. It is based on the observation that the low angular-momentum states of an SU(3) irrep have properties that mimic those of a corresponding irrep of the rotor algebra. Thus, we show that strongly coupled spin-SU(3) bands behave like strongly coupled rotor bands with properties that approach those of irreducible representations of the rigid-rotor algebra in the limit of large SU(3) quantum numbers. Moreover, we determine that the low angular-momentum states of a strongly coupled band of states of half-odd integer angular momentum behave to a high degree of accuracy as if they belonged to an SU(3) irrep. These are the quasispinor SU(3) irreps referred to in the title. (orig.)

Cannabinoids disrupt memory encoding by functionally isolating hippocampal CA1 from CA3.

Directory of Open Access Journals (Sweden)

Roman A Sandler

2017-07-01

Full Text Available Much of the research on cannabinoids (CBs has focused on their effects at the molecular and synaptic level. However, the effects of CBs on the dynamics of neural circuits remains poorly understood. This study aims to disentangle the effects of CBs on the functional dynamics of the hippocampal Schaffer collateral synapse by using data-driven nonparametric modeling. Multi-unit activity was recorded from rats doing an working memory task in control sessions and under the influence of exogenously administered tetrahydrocannabinol (THC, the primary CB found in marijuana. It was found that THC left firing rate unaltered and only slightly reduced theta oscillations. Multivariate autoregressive models, estimated from spontaneous spiking activity, were then used to describe the dynamical transformation from CA3 to CA1. They revealed that THC served to functionally isolate CA1 from CA3 by reducing feedforward excitation and theta information flow. The functional isolation was compensated by increased feedback excitation within CA1, thus leading to unaltered firing rates. Finally, both of these effects were shown to be correlated with memory impairments in the working memory task. By elucidating the circuit mechanisms of CBs, these results help close the gap in knowledge between the cellular and behavioral effects of CBs.

A remarkable representation of the SO(3,2) Kac-Moody algebra

International Nuclear Information System (INIS)

Dobrev, V.K.; Sezgin, E.

1990-01-01

We construct a minimal representation of the SO(3,2) Kac-Moody algebra algebra which is based on the spin-zero singleton (the Rac) representation of SO(3,2). The representation is minimal in the sense that the central charge k of the SO(3,2) Kac-Moody algebra is chosen to take the special value of 5/2 which allows the imposition of maximum number of reducibility conditions. For the Rac, this is the unique choice for the remarkable property of maximum reducibility which is consistent with unitarity. To ensure unitarity, we furthermore impose invariance condition under the maximal compact subalgebra SO(3) x SO(2). (author). 19 refs, 1 fig

Sol–gel synthesis and photoluminescence of CaTi1–x Zrx O3: Pr 3 ...

Indian Academy of Sciences (India)

The strongest red excitation obtained from CaTi1–ZrO3 : Pr3+ ( = 4/300) and CaTi1–ZrO3 : Pr3+ ( = 5/300) possesses the strongest emission at 610 nm, similar to the intensities of Ca(Ti1–Zr)O3 : Pr3+ ( = 3/300, 4/300, 6/300), which may be corresponded to the cell parameters of CaTi1–ZrO3 : Pr3+.

Luminescence and energy transfer of Sm3+ and Eu3+ in Ca2PO4Cl

International Nuclear Information System (INIS)

Wang, Zhijun; Li, Panlai; Yang, Zhiping; Guo, Qinglin

2014-01-01

Sm 3+ , Eu 3+ , and Sm 3+ –Eu 3+ doped Ca 2 PO 4 Cl phosphors are synthesized by a solid-state method. Ca 2 PO 4 Cl:Sm 3+ can produce red emission under the 400 nm radiation excitation, and the emission peak is located at 601 nm, which is assigned to the 4 G 5/2 → 6 H 7/2 transition of Sm 3+ . Ca 2 PO 4 Cl:Eu 3+ can create red emission under the 392 nm radiation excitation, and the strongest peak is located at 620 nm, which is attributed to the 5 D 0 → 7 F 2 transition of Eu 3+ . The energy transfer from Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl has been validated and the critical distance (R c ) of Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl is calculated to be 1.14 nm. With increasing Eu 3+ doping concentration, the energy transfer efficiency (Sm 3+ →Eu 3+ ) gradually increases to 53.7%. The luminescence property of Ca 2 PO 4 Cl:Sm 3+ , Eu 3+ can be tuned by properly tuning the relative ratio of Sm 3+ –Eu 3+ , and the emission intensity of Ca 2 PO 4 Cl:Eu 3+ can be greatly enhanced by codoped Sm 3+ . - Highlights: • Ca 2 PO 4 Cl:Sm 3+ , Eu 3+ can produce red emission under the 400 nm radiation excitation. • The energy transfer from Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl has been validated. • The critical distance of Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl is calculated to be 1.14 nm

Facile combustion synthesis of novel CaZrO 3

Indian Academy of Sciences (India)

Abstract. A facile sol–gel combustion route was reported for the direct preparation of CaZrO3:Eu3+ and CaZrO3:Eu3+, Gd3+. The obtained deposits were characterized by XRD, TGA-DSC, SEM, EDS, PL measurements and microscope fluorescence. When the Gd3+ ions were introduced in this compound, the emissions of ...

Rapid recycling of Ca2+ between IP3-sensitive stores and lysosomes.

Directory of Open Access Journals (Sweden)

Cristina I López Sanjurjo

Full Text Available Inositol 1,4,5-trisphosphate (IP3 evokes release of Ca2+ from the endoplasmic reticulum (ER, but the resulting Ca2+ signals are shaped by interactions with additional intracellular organelles. Bafilomycin A1, which prevents lysosomal Ca2+ uptake by inhibiting H+ pumping into lysosomes, increased the amplitude of the initial Ca2+ signals evoked by carbachol in human embryonic kidney (HEK cells. Carbachol alone and carbachol in combination with parathyroid hormone (PTH evoke Ca2+ release from distinct IP3-sensitive Ca2+ stores in HEK cells stably expressing human type 1 PTH receptors. Bafilomycin A1 similarly exaggerated the Ca2+ signals evoked by carbachol or carbachol with PTH, indicating that Ca2+ released from distinct IP3-sensitive Ca2+ stores is sequestered by lysosomes. The Ca2+ signals resulting from store-operated Ca2+ entry, whether evoked by thapsigargin or carbachol, were unaffected by bafilomycin A1. Using Gd3+ (1 mM to inhibit both Ca2+ entry and Ca2+ extrusion, HEK cells were repetitively stimulated with carbachol to assess the effectiveness of Ca2+ recycling to the ER after IP3-evoked Ca2+ release. Blocking lysosomal Ca2+ uptake with bafilomycin A1 increased the amplitude of each carbachol-evoked Ca2+ signal without affecting the rate of Ca2+ recycling to the ER. This suggests that Ca2+ accumulated by lysosomes is rapidly returned to the ER. We conclude that lysosomes rapidly, reversibly and selectively accumulate the Ca2+ released by IP3 receptors residing within distinct Ca2+ stores, but not the Ca2+ entering cells via receptor-regulated, store-operated Ca2+ entry pathways.

Rapid recycling of Ca2+ between IP3-sensitive stores and lysosomes.

Science.gov (United States)

López Sanjurjo, Cristina I; Tovey, Stephen C; Taylor, Colin W

2014-01-01

Inositol 1,4,5-trisphosphate (IP3) evokes release of Ca2+ from the endoplasmic reticulum (ER), but the resulting Ca2+ signals are shaped by interactions with additional intracellular organelles. Bafilomycin A1, which prevents lysosomal Ca2+ uptake by inhibiting H+ pumping into lysosomes, increased the amplitude of the initial Ca2+ signals evoked by carbachol in human embryonic kidney (HEK) cells. Carbachol alone and carbachol in combination with parathyroid hormone (PTH) evoke Ca2+ release from distinct IP3-sensitive Ca2+ stores in HEK cells stably expressing human type 1 PTH receptors. Bafilomycin A1 similarly exaggerated the Ca2+ signals evoked by carbachol or carbachol with PTH, indicating that Ca2+ released from distinct IP3-sensitive Ca2+ stores is sequestered by lysosomes. The Ca2+ signals resulting from store-operated Ca2+ entry, whether evoked by thapsigargin or carbachol, were unaffected by bafilomycin A1. Using Gd3+ (1 mM) to inhibit both Ca2+ entry and Ca2+ extrusion, HEK cells were repetitively stimulated with carbachol to assess the effectiveness of Ca2+ recycling to the ER after IP3-evoked Ca2+ release. Blocking lysosomal Ca2+ uptake with bafilomycin A1 increased the amplitude of each carbachol-evoked Ca2+ signal without affecting the rate of Ca2+ recycling to the ER. This suggests that Ca2+ accumulated by lysosomes is rapidly returned to the ER. We conclude that lysosomes rapidly, reversibly and selectively accumulate the Ca2+ released by IP3 receptors residing within distinct Ca2+ stores, but not the Ca2+ entering cells via receptor-regulated, store-operated Ca2+ entry pathways.

Differentiating Spatial Memory from Spatial Transformations

Science.gov (United States)

Street, Whitney N.; Wang, Ranxiao Frances

2014-01-01

The perspective-taking task is one of the most common paradigms used to study the nature of spatial memory, and better performance for certain orientations is generally interpreted as evidence of spatial representations using these reference directions. However, performance advantages can also result from the relative ease in certain…

A Review On Accuracy and Uncertainty of Spatial Data and Analyses with special reference to Urban and Hydrological Modelling

Science.gov (United States)

Devendran, A. A.; Lakshmanan, G.

2014-11-01

Data quality for GIS processing and analysis is becoming an increased concern due to the accelerated application of GIS technology for problem solving and decision making roles. Uncertainty in the geographic representation of the real world arises as these representations are incomplete. Identification of the sources of these uncertainties and the ways in which they operate in GIS based representations become crucial in any spatial data representation and geospatial analysis applied to any field of application. This paper reviews the articles on the various components of spatial data quality and various uncertainties inherent in them and special focus is paid to two fields of application such as Urban Simulation and Hydrological Modelling. Urban growth is a complicated process involving the spatio-temporal changes of all socio-economic and physical components at different scales. Cellular Automata (CA) model is one of the simulation models, which randomly selects potential cells for urbanisation and the transition rules evaluate the properties of the cell and its neighbour. Uncertainty arising from CA modelling is assessed mainly using sensitivity analysis including Monte Carlo simulation method. Likewise, the importance of hydrological uncertainty analysis has been emphasized in recent years and there is an urgent need to incorporate uncertainty estimation into water resources assessment procedures. The Soil and Water Assessment Tool (SWAT) is a continuous time watershed model to evaluate various impacts of land use management and climate on hydrology and water quality. Hydrological model uncertainties using SWAT model are dealt primarily by Generalized Likelihood Uncertainty Estimation (GLUE) method.

Chemical purification of CaCO{sub 3} and CaWO{sub 4} powders used for CaWO{sub 4} crystal production for the CRESST experiment

Energy Technology Data Exchange (ETDEWEB)

Trinh Thi, H.H.; Defay, X.; Erb, A.; Hampf, R.; Lanfranchi, J.C.; Langenkaemper, A.; Morgalyuk, V.; Muenster, A.; Mondragon, E.; Oppenheimer, C.; Potzel, W.; Schoenert, S.; Steiger, H.; Ulrich, A.; Wawoczny, S.; Willers, M.; Zoeller, A. [Physik-Department and Excellence Cluster Universe, Technische Universitaet Muenchen, Garching (Germany)

2016-07-01

CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) uses CaWO{sub 4} single crystals as targets for the direct search for dark matter particles. Since several years these CaWO{sub 4} crystals are grown at the Technische Universitaet Muenchen. Thereby, commercially available CaCO{sub 3} and WO{sub 3} powders are used for the synthesis of CaWO{sub 4} powder. For the experiment low intrinsic contaminations of the crystals play a crucial role. In order to improve the radiopurity of the crystals it is necessary to reduce potential sources for radioactive backgrounds such as U and Th. In this poster we will present our studies of the chemical purification of the CaCO{sub 3} and CaWO{sub 4} powders.

Preparation and tunable luminescence of CaCO{sub 3}: Eu{sup 3+}, Tb{sup 3+} phosphors

Energy Technology Data Exchange (ETDEWEB)

Cheng, Qijun; Dong, Yanwei; Kang, Ming, E-mail: dyw510@126.com; Zhang, Ping

2014-12-15

Luminescent tunable phosphors CaCO{sub 3}: Eu{sup 3+}, Tb{sup 3+} were synthesized by a microwave co-precipitation method. The structure and micro-morphology of samples were characterized and analyzed by an X-ray powder diffraction (XRD) and a scanning electronic microscope (SEM), results showed that Tb{sup 3+} and Eu{sup 3+} ions were uniformly introduced into the host lattice of CaCO{sub 3} entering substitutionally in Ca{sup 2+} sites. The photoluminescence (PL) properties were characterized by PL, PL excitation spectroscopy and chromaticity coordinates. Under the excitation at 235 nm and 267 nm, the transitions of {sup 5}D{sub 4}→{sup 7}F{sub J} (J=3–6) for Tb{sup 3+} and {sup 5}D{sub 0}→{sup 7}F{sub J} (J=0–3) for Eu{sup 3+} were observed, and the luminescent intensities and emitting colors of Eu{sup 3+}–Tb{sup 3+} co-doped CaCO{sub 3} phosphors could be gradually changed between red and green by changing the Eu/Tb atomic ratio and the excitation wavelength. - highlights: • A new phosphor CaCO{sub 3}: Eu{sup 3+}, Tb{sup 3+} was prepared by the microwave co-precipitation method. • The phosphors exhibited green and red color under UV excitation. • The emission color could be gradually tuned between green and red. • The phosphors had the potential as materials for anti-counterfeiting technologies.

Significance of the tumor markers CA 125 and CA 15-3 in postoperative diagnosis of ovarian and breast cancer

International Nuclear Information System (INIS)

Johannsen, B.; Bartel, U.; Elling, D.

1989-01-01

In 271 patients with ovarian carcinoma, benign ovarian tumors, breast cancer, and two control groups, serum levels of CA 125, CA 15-3, CEA and, partly, CA 19-9 were determined immunoradiometrically. According to the results of the determination of CA 125 in the follow-up of ovarian carcinoma, CA 125 represents a useful marker for early detection of recurrences, especially in cases of diffuse carcinoma dissemination. In incomplete tumor debulking, postoperative CA 125 serum levels did not prove to be helpful except that a positive level renders invasive diagnostic investigation no longer necessary. Postoperative follow-up in breast cancer early reveals distant metastases, with very high levels in patients with bone metastases. By simultaneous measurement of CA 15-3 and CEA the sensitivity could be increased from 86% (CA 15-3 only) to 93%. (author)

Post-perovskite transitions in CaB4+O3 at high pressure

International Nuclear Information System (INIS)

Akaogi, M; Shirako, Y; Kojitani, H; Takamori, S; Yamaura, K; Takayama-Muromachi, E

2010-01-01

High-pressure phase transitions in CaRhO 3 were examined using a multianvil apparatus up to 27 GPa and 1930 o C. CaRhO 3 perovskite transforms to post-perovskite via a monoclinic intermediate phase with increasing pressure. Volume changes for the transitions of perovskite - intermediate phase and of intermediate phase - post-perovskite are -1.1 and -0.7 %, respectively. CaRhO 3 post-perovskite is the fourth quenchable post-perovskite oxide found so far. By high-temperature calorimetric experiments, enthalpy of the perovskite - post-perovskite transition in CaRuO 3 was measured as 15.2±3.3 kJ/mol. Combining the datum with those of CaIrO 3 , it is shown that CaIrO 3 perovskite is energetically less stable than CaRuO 3 perovskite. This is consistent with the fact that orthorhombic distortion of CaIrO 3 perovskite is larger than CaRuO 3 , as indicated with the tilt-angle of octahedral framework of perovskite structure. The transition pressure from perovskite to post-perovskite in CaBO 3 (B = Ru, Rh, Ir) increases almost linearly with decreasing the tilt-angle, suggesting that the perovskite - post-perovskite transition may result from instability of the perovskite structure with pressure.

Formation of carrageenan-CaCO{sub 3} bioactive membranes

Energy Technology Data Exchange (ETDEWEB)

Nogueira, Lucas F.B.; Maniglia, Bianca C.; Pereira, Lourivaldo S.; Tapia-Blácido, Delia R.; Ramos, Ana P., E-mail: anapr@ffclrp.usp.br

2016-01-01

The high biocompatibility and resorbability of polymeric membranes have encouraged their use to manufacture medical devices. Here, we report on the preparation of membranes consisting of carrageenan, a naturally occurring sulfated polysaccharide that forms helical structures in the presence of calcium ions. We incorporated CaCO{sub 3} particles into the membranes to enhance their bioactivity and mechanical properties. Infrared spectroscopy and X-ray diffraction data confirmed CaCO{sub 3} incorporation into the polymeric matrix. We tested the bioactivity of the samples by immersing them in a solution that mimics the ionic composition and pH of the human body fluid. The hybrid membranes generated hydroxyapatite, as attested by X-ray diffraction data. Scanning electron and atomic force microscopies aided investigation of membrane topography before and after CaCO{sub 3} deposition. The wettability and surface free energy, evaluated by contact angle measures, increased in the presence of CaCO{sub 3} particles. These parameters are important for membrane implantation in the body. Moreover, membrane stiffness was up to 110% higher in the presence of the inorganic particles, as revealed by Young's modulus. - Highlights: • Hybrid kappa and iota carrageenan-CaCO{sub 3} membranes were formed. • The hybrid membrane's origin hydroxyapatite after exposure to simulated body fluid • The carrageenan's specificity to bind Ca{sup 2+} ions tailors the surface properties.

Improving 3d Spatial Queries Search: Newfangled Technique of Space Filling Curves in 3d City Modeling

Science.gov (United States)

Uznir, U.; Anton, F.; Suhaibah, A.; Rahman, A. A.; Mioc, D.

2013-09-01

The advantages of three dimensional (3D) city models can be seen in various applications including photogrammetry, urban and regional planning, computer games, etc.. They expand the visualization and analysis capabilities of Geographic Information Systems on cities, and they can be developed using web standards. However, these 3D city models consume much more storage compared to two dimensional (2D) spatial data. They involve extra geometrical and topological information together with semantic data. Without a proper spatial data clustering method and its corresponding spatial data access method, retrieving portions of and especially searching these 3D city models, will not be done optimally. Even though current developments are based on an open data model allotted by the Open Geospatial Consortium (OGC) called CityGML, its XML-based structure makes it challenging to cluster the 3D urban objects. In this research, we propose an opponent data constellation technique of space-filling curves (3D Hilbert curves) for 3D city model data representation. Unlike previous methods, that try to project 3D or n-dimensional data down to 2D or 3D using Principal Component Analysis (PCA) or Hilbert mappings, in this research, we extend the Hilbert space-filling curve to one higher dimension for 3D city model data implementations. The query performance was tested using a CityGML dataset of 1,000 building blocks and the results are presented in this paper. The advantages of implementing space-filling curves in 3D city modeling will improve data retrieval time by means of optimized 3D adjacency, nearest neighbor information and 3D indexing. The Hilbert mapping, which maps a subinterval of the [0, 1] interval to the corresponding portion of the d-dimensional Hilbert's curve, preserves the Lebesgue measure and is Lipschitz continuous. Depending on the applications, several alternatives are possible in order to cluster spatial data together in the third dimension compared to its

Cation-exchange antibody labeling for simultaneous electrochemical detection of tumor markers CA15-3 and CA19-9

International Nuclear Information System (INIS)

Wang, Guangjie; Qing, Yi; Shan, Jinlu; Jin, Feng; Wang, Dong; Yuan, Ruo

2013-01-01

We report on a new kind of non-covalent multi-label electrochemical immunoassay that was applied to simultaneously quantify the tumor markers CA15-3 and CA19-9. The method employs a nanohybrid composed of an ionomer and conductive titanium dioxide nanoparticles that act as a matrix support for the antibodies. The two antibodies (anti-CA153 and anti-CA199) were labeled (a) with a cobaltous dipyridine complex, and (b) with methylene blue. Labeling is based on cation-exchange interaction rather than on covalent conjugation. The redox potentials of the two labels are separated by an interval of 0.3 V. The resulting sandwich-type immunosensor was read out by differential pulse voltammetry. The potential sites and currents of the two redox probes reflect the concentration of the two analytes. The two analytes were determined with a detection limit of 1.6 U mL −1 for CA19-9, and of 0.3 U mL −1 for CA15-3 (author)

Radiolysis of Ca14CO3

International Nuclear Information System (INIS)

Sanchez, M.G.A.

1986-01-01

The partition-ion exclusion chromatography is evaluated to analyse non-ionic organic compounds obtained from radiolysis of high specific activity Ca 14 CO 3 . The Ca 14 CO 3 was irradiated by β - decay of carbon-14 or by γ rays from a cobalt-60 source. The crystals were dissolved for qualitative and quantitative analysis of the radiolytic products. Formic and oxalic acids were produced in high yields. Glyoxylic, acetic and glycolic acids, formaldehyde and methanol were produced in low yields. Quantitative determination was carried out by liquid scintillation spectroscopy and the chemical yields (G-values) were calculated for the products. Mechanisms of product formation are proposed based on thermal annealing experiments. (Author) [pt

Electrical and magnetic behavior of La0.7Ca0.3MnO3/La0.7Sr0.2Ca0.1MnO3 composites

International Nuclear Information System (INIS)

Phong, P.T.; Dai, N.V.; Manh, D.H.; Thanh, T.D.; Khiem, N.V.; Hong, L.V.; Phuc, N.X.

2010-01-01

The electrical transport properties and the magnetoresistance of La 0.7 Ca 0.3 MnO 3 /La 0.7 Sr 0.2 Ca 0.1 MnO 3 composites are investigated as a function of sintering temperature. On the basis of an analysis by X-ray powder diffraction and scanning electron microscopy we suggest that raising the sintering temperature enhanced the interfacial reaction and creates interfacial phases at the boundaries of the La 0.7 Ca 0.3 MnO 3 and La 0.7 Sr 0.2 Ca 0.1 MnO 3 . Results also show that in 3 kOe, and at the Curie temperature, the magnetoresistance value of 14% was observed for the composite sintered at 1300 o C. Based on the phenomenological equation for conductivity under a percolation approach, which depends on the phase segregation of ferromagnetic metallic clusters and paramagnetic insulating regions, we fitted the experimental resistivity-temperature data from 50-300 K and find that the activation barrier decreases as temperature is increased.

Chronic Loss of CA2 Transmission Leads to Hippocampal Hyperexcitability.

Science.gov (United States)

Boehringer, Roman; Polygalov, Denis; Huang, Arthur J Y; Middleton, Steven J; Robert, Vincent; Wintzer, Marie E; Piskorowski, Rebecca A; Chevaleyre, Vivien; McHugh, Thomas J

2017-05-03

Hippocampal CA2 pyramidal cells project into both the neighboring CA1 and CA3 subfields, leaving them well positioned to influence network physiology and information processing for memory and space. While recent work has suggested unique roles for CA2, including encoding position during immobility and generating ripple oscillations, an interventional examination of the integrative functions of these connections has yet to be reported. Here we demonstrate that CA2 recruits feedforward inhibition in CA3 and that chronic genetically engineered shutdown of CA2-pyramidal-cell synaptic transmission consequently results in increased excitability of the recurrent CA3 network. In behaving mice, this led to spatially triggered episodes of network-wide hyperexcitability during exploration accompanied by the emergence of high-frequency discharges during rest. These findings reveal CA2 as a regulator of network processing in hippocampus and suggest that CA2-mediated inhibition in CA3 plays a key role in establishing the dynamic excitatory and inhibitory balance required for proper network function. Copyright © 2017 Elsevier Inc. All rights reserved.

Electronic Structure and Thermoelectric Properties of Ca3 Co4O9

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The relation among electronic structure, chemical bond and thermoelectric property of Ca3 Co4 O9 was studied using density function and discrete variation method (DFT-DVM).The gap between the highest valence band (HVB) and the lowest conduction band (LCB) shows a semiconducting property.Ca3 Co4 O9 colsists of CoO2 and Ca2 CoO3 two layers.The HVB and LCB near Fermi level are only mainly from O(2) 2p and Co(2) 3d in Ca2 CoO3 layer. Therefore, the semiconducting or thermoelectric property of Ca3 Co4 O9 should be mainly from Ca2 CoO3 layer, but it seems to have no direct relation to the CoO2 layer,which is consistent with that binary oxides hardly have a thermoelectric property, but trinary oxide compounds have quite a good thermoelectric property.The covalent and ionic bonds of Ca2 CoO3 layer are both weaker than those of CoO2 layer.Ca plays the role of connections between CoO2 and Ca2 CoO3 layers in Ca3 Co4 O9, decrease the ionic and covalent bond strength, and improve the thermoelectric property.

3D geospatial visualizations: Animation and motion effects on spatial objects

Science.gov (United States)

Evangelidis, Konstantinos; Papadopoulos, Theofilos; Papatheodorou, Konstantinos; Mastorokostas, Paris; Hilas, Constantinos

2018-02-01

Digital Elevation Models (DEMs), in combination with high quality raster graphics provide realistic three-dimensional (3D) representations of the globe (virtual globe) and amazing navigation experience over the terrain through earth browsers. In addition, the adoption of interoperable geospatial mark-up languages (e.g. KML) and open programming libraries (Javascript) makes it also possible to create 3D spatial objects and convey on them the sensation of any type of texture by utilizing open 3D representation models (e.g. Collada). One step beyond, by employing WebGL frameworks (e.g. Cesium.js, three.js) animation and motion effects are attributed on 3D models. However, major GIS-based functionalities in combination with all the above mentioned visualization capabilities such as for example animation effects on selected areas of the terrain texture (e.g. sea waves) as well as motion effects on 3D objects moving in dynamically defined georeferenced terrain paths (e.g. the motion of an animal over a hill, or of a big fish in an ocean etc.) are not widely supported at least by open geospatial applications or development frameworks. Towards this we developed and made available to the research community, an open geospatial software application prototype that provides high level capabilities for dynamically creating user defined virtual geospatial worlds populated by selected animated and moving 3D models on user specified locations, paths and areas. At the same time, the generated code may enhance existing open visualization frameworks and programming libraries dealing with 3D simulations, with the geospatial aspect of a virtual world.

Infrared spectroscopic study of CaFe0.7Co0.3O3

Science.gov (United States)

Zhang, C. X.; Xia, H. L.; Dai, Y. M.; Qiu, Z. Y.; Sui, Q. T.; Long, Y. W.; Qiu, X. G.

2017-08-01

Temperature-dependent infrared spectroscopy has been investigated for CaFe0.7Co0.3O3 which undergoes a ferromagnetic transition at TC≈177 K . It is observed that the spectral weight is transferred from ˜4800 -14 000 cm-1 to ˜0 -4800 cm-1 as the temperature is lowered around TC. Such a large-range spectral weight transfer is attributed to the Hund's interaction. The phonons in CaFe0.7Co0.3O3 show minor asymmetric line shapes, implying relatively weak electron-phonon coupling compared with the parent compound CaFeO3. The optical conductivity also reveals a broad peak structure in the range of ˜700 -1500 cm-1. Fit by the model of single-polaron absorption, the broad peak is interpreted by the excitation of polarons. From the fitting parameters of the polaron peak, we estimate the electron-phonon coupling constant α ˜ 0.4 -0.5 , implying that CaFe0.7Co0.3O3 falls into the weak-coupling regime.

Ablation of NMDA receptors enhances the excitability of hippocampal CA3 neurons.

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Fumiaki Fukushima

Full Text Available Synchronized discharges in the hippocampal CA3 recurrent network are supposed to underlie network oscillations, memory formation and seizure generation. In the hippocampal CA3 network, NMDA receptors are abundant at the recurrent synapses but scarce at the mossy fiber synapses. We generated mutant mice in which NMDA receptors were abolished in hippocampal CA3 pyramidal neurons by postnatal day 14. The histological and cytological organizations of the hippocampal CA3 region were indistinguishable between control and mutant mice. We found that mutant mice lacking NMDA receptors selectively in CA3 pyramidal neurons became more susceptible to kainate-induced seizures. Consistently, mutant mice showed characteristic large EEG spikes associated with multiple unit activities (MUA, suggesting enhanced synchronous firing of CA3 neurons. The electrophysiological balance between fast excitatory and inhibitory synaptic transmission was comparable between control and mutant pyramidal neurons in the hippocampal CA3 region, while the NMDA receptor-slow AHP coupling was diminished in the mutant neurons. In the adult brain, inducible ablation of NMDA receptors in the hippocampal CA3 region by the viral expression vector for Cre recombinase also induced similar large EEG spikes. Furthermore, pharmacological blockade of CA3 NMDA receptors enhanced the susceptibility to kainate-induced seizures. These results raise an intriguing possibility that hippocampal CA3 NMDA receptors may suppress the excitability of the recurrent network as a whole in vivo by restricting synchronous firing of CA3 neurons.

Cathodoluminescence and Raman characteristics of CaSO{sub 4}:Tm{sup 3+}, Cu phosphor

Energy Technology Data Exchange (ETDEWEB)

Ekdal, E. [Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir (Turkey); Guinea, J. Garcia [MuseoNacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Kelemen, A. [Centre for Energy Research, Radiation Safety Laboratory, P.O. Box 49, H-1121 Budapest (Hungary); Ayvacikli, M. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Canimoglu, A. [Nigde University, Faculty of Arts and Sciences, Department of Physics, Nigde (Turkey); Jorge, A. [MuseoNacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Karali, T. [Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir (Turkey); Can, N., E-mail: cannurdogan@yahoomail.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Physics Department, Jazan University, P.O. Box 114, 45142 Jazan (Saudi Arabia)

2015-05-15

The physical characterization and phosphor emission spectra are presented for CaSO{sub 4} doped with Tm and Cu. All spectral wavelengths are related to electronic transitions of Tm{sup 3+} ions. The powder X-ray diffraction pattern showed that the compound exhibits orthorhombic structure and all reflections were indexed without any other secondary impurity phases. Chemical and structural properties of the samples have been characterized by means of Raman spectroscopy and environmental scanning electron microscope (ESEM) with an attached X-ray energy dispersive system (EDS). Group frequencies concept is essential point to the interpretation of the bands due to the main SO{sub 4} vibrational units and these displayed main characteristic intensive Raman bands including typical strong intensity at 1016 cm{sup −1} that corresponds to ν{sub 1}SO{sub 4} vibrational mode. From the spatially-resolved cathodoluminescence (CL) spectrum, main emission bands of Tm{sup 3+} centered at 346, 362, and 452 nm, due to the respective transitions of {sup 3}P{sub 0}→{sup 3}H{sub 4}, {sup 1}D{sub 2}→{sup 3}H{sub 6}, {sup 1}D{sub 2}→{sup 3}F{sub 4} were clearly identified. The study is novel as no such CL-ESEM data are available for this doped compound. - Highlights: • Characteristic and cathodoluminescence properties of CaSO{sub 4}:Tm{sup 3+}, Cu have been investigated. • Several sharp and strong CL emission bands due to rare earth ion were observed for rare earth doped sample. • The nature and limitation of the interaction between CaSO{sub 4} and the activator ions were discussed.

3D ear identification based on sparse representation.

Directory of Open Access Journals (Sweden)

Lin Zhang

Full Text Available Biometrics based personal authentication is an effective way for automatically recognizing, with a high confidence, a person's identity. Recently, 3D ear shape has attracted tremendous interests in research field due to its richness of feature and ease of acquisition. However, the existing ICP (Iterative Closet Point-based 3D ear matching methods prevalent in the literature are not quite efficient to cope with the one-to-many identification case. In this paper, we aim to fill this gap by proposing a novel effective fully automatic 3D ear identification system. We at first propose an accurate and efficient template-based ear detection method. By utilizing such a method, the extracted ear regions are represented in a common canonical coordinate system determined by the ear contour template, which facilitates much the following stages of feature extraction and classification. For each extracted 3D ear, a feature vector is generated as its representation by making use of a PCA-based local feature descriptor. At the stage of classification, we resort to the sparse representation based classification approach, which actually solves an l1-minimization problem. To the best of our knowledge, this is the first work introducing the sparse representation framework into the field of 3D ear identification. Extensive experiments conducted on a benchmark dataset corroborate the effectiveness and efficiency of the proposed approach. The associated Matlab source code and the evaluation results have been made publicly online available at http://sse.tongji.edu.cn/linzhang/ear/srcear/srcear.htm.

The effects of CCK-8S on spatial memory and long-term potentiation at CA1 during induction of stress in rats

Directory of Open Access Journals (Sweden)

Malihe Sadeghi

2017-12-01

Full Text Available Objective(s: Cholecystokinin (CCK has been proposed as a mediator in stress. However, it is still not fully documented what are its effects. We aimed to evaluate the effects of systemic administration of CCK exactly before induction of stress on spatial memory and synaptic plasticity at CA1 in rats. Materials and Methods: Male Wistar rats were divided into 4 groups: the control, the control-CCK, the stress and the stress-CCK. Restraint stress was induced 6 hr per day, for 24 days. Cholecystokinin sulfated octapeptide (CCK-8S was injected (1.6 µg/kg, IP before each session of stress induction. Spatial memory was evaluated by Morris water maze test. Long term potentiation (LTP in Schaffer collateral-CA1 synapses was assessed (by 100 Hz tetanization in order to investigate synaptic plasticity. Results: Stress impaired spatial memory significantly (P

IP3 Receptor-Dependent Cytoplasmic Ca2+ Signals Are Tightly Controlled by Cavβ3

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Anouar Belkacemi

2018-01-01

Full Text Available Voltage-gated calcium channels (Cavs are major Ca2+ entry pathways in excitable cells. Their β subunits facilitate membrane trafficking of the channel’s ion-conducting α1 pore and modulate its gating properties. We report that one β subunit, β3, reduces Ca2+ release following stimulation of phospholipase C-coupled receptors and inositol 1,4,5-trisphosphate (IP3 formation. This effect requires the SH3-HOOK domain of Cavβ3, includes physical β3/IP3 receptor interaction, and prevails when agonist-induced IP3 formation is bypassed by photolysis of caged IP3. In agreement with β3 acting as a brake on Ca2+ release, fibroblast migration is enhanced in vitro, and in vivo, closure of skin wounds is accelerated in the absence of β3. To mediate specific physiological responses and to prevent Ca2+ toxicity, cytoplasmic Ca2+ signals must be tightly controlled. The described function of β3, unrelated to its function as a Cav subunit, adds to this tight control.

Spatial representation and cognitive modulation of response variability in the lateral intraparietal area priority map.

Science.gov (United States)

Falkner, Annegret L; Goldberg, Michael E; Krishna, B Suresh

2013-10-09

The lateral intraparietal area (LIP) in the macaque contains a priority-based representation of the visual scene. We previously showed that the mean spike rate of LIP neurons is strongly influenced by spatially wide-ranging surround suppression in a manner that effectively sharpens the priority map. Reducing response variability can also improve the precision of LIP's priority map. We show that when a monkey plans a visually guided delayed saccade with an intervening distractor, variability (measured by the Fano factor) decreases both for neurons representing the saccade goal and for neurons representing the broad spatial surround. The reduction in Fano factor is maximal for neurons representing the saccade goal and steadily decreases for neurons representing more distant locations. LIP Fano factor changes are behaviorally significant: increasing expected reward leads to lower variability for the LIP representation of both the target and distractor locations, and trials with shorter latency saccades are associated with lower Fano factors in neurons representing the surround. Thus, the LIP Fano factor reflects both stimulus and behavioral engagement. Quantitative modeling shows that the interaction between mean spike count and target-receptive field (RF) distance in the surround during the predistractor epoch is multiplicative: the Fano factor increases more steeply with mean spike count further away from the RF. A negative-binomial model for LIP spike counts captures these findings quantitatively, suggests underlying mechanisms based on trial-by-trial variations in mean spike rate or burst-firing patterns, and potentially provides a principled framework to account simultaneously for the previously observed unsystematic relationships between spike rate and variability in different brain areas.

Neuronal migration and its disorders affecting the CA3 region

Directory of Open Access Journals (Sweden)

Richard eBelvindrah

2014-03-01

Full Text Available In this review, we focus on CA3 neuronal migration disorders in the rodent. We begin by introducing the main steps of hippocampal development, and we summarize characteristic hippocampal malformations in human. We then describe various mouse mutants showing structural hippocampal defects. Notably, genes identified in human cortical neuronal migration disorders consistently give rise to a CA3 phenotype when mutated in the mouse. We successively describe their molecular, physiological and behavioral phenotypes that together contribute to a better understanding of CA3-dependent functions. We finally discuss potential factors underlying the CA3 vulnerability revealed by these mouse mutants and that may also contribute to other human neurological and psychiatric disorders.

Coupled Ca2+/H+ transport by cytoplasmic buffers regulates local Ca2+ and H+ ion signaling.

Science.gov (United States)

Swietach, Pawel; Youm, Jae-Boum; Saegusa, Noriko; Leem, Chae-Hun; Spitzer, Kenneth W; Vaughan-Jones, Richard D

2013-05-28

Ca(2+) signaling regulates cell function. This is subject to modulation by H(+) ions that are universal end-products of metabolism. Due to slow diffusion and common buffers, changes in cytoplasmic [Ca(2+)] ([Ca(2+)]i) or [H(+)] ([H(+)]i) can become compartmentalized, leading potentially to complex spatial Ca(2+)/H(+) coupling. This was studied by fluorescence imaging of cardiac myocytes. An increase in [H(+)]i, produced by superfusion of acetate (salt of membrane-permeant weak acid), evoked a [Ca(2+)]i rise, independent of sarcolemmal Ca(2+) influx or release from mitochondria, sarcoplasmic reticulum, or acidic stores. Photolytic H(+) uncaging from 2-nitrobenzaldehyde also raised [Ca(2+)]i, and the yield was reduced following inhibition of glycolysis or mitochondrial respiration. H(+) uncaging into buffer mixtures in vitro demonstrated that Ca(2+) unloading from proteins, histidyl dipeptides (HDPs; e.g., carnosine), and ATP can underlie the H(+)-evoked [Ca(2+)]i rise. Raising [H(+)]i tonically at one end of a myocyte evoked a local [Ca(2+)]i rise in the acidic microdomain, which did not dissipate. The result is consistent with uphill Ca(2+) transport into the acidic zone via Ca(2+)/H(+) exchange on diffusible HDPs and ATP molecules, energized by the [H(+)]i gradient. Ca(2+) recruitment to a localized acid microdomain was greatly reduced during intracellular Mg(2+) overload or by ATP depletion, maneuvers that reduce the Ca(2+)-carrying capacity of HDPs. Cytoplasmic HDPs and ATP underlie spatial Ca(2+)/H(+) coupling in the cardiac myocyte by providing ion exchange and transport on common buffer sites. Given the abundance of cellular HDPs and ATP, spatial Ca(2+)/H(+) coupling is likely to be of general importance in cell signaling.

Combined Evaluation of AFP, CA15-3, CA125, CA19-9, and CEA Tumor Markers in Patients with Hepatitis B and C.

Science.gov (United States)

Assmar, Mehdi; Yeganeh, Sara; Mansourghanaei, Fariborz; Amirmozafari, Nour

2016-12-01

This study aimed to determine the role of tumor markers AFP, CA15-3, CA125, CA19-9 and CEA in patients with hepatitis B and C. This descriptive cross-sectional study was performed from Oct 2012 to Oct 2014. Serum samples of 129 patients with hepatitis B and C referred to Guilan Liver and Digestive Disease Research Center in Rasht, Iran were collected and checked for the existence of the listed tumor markers by ELISA. No increase in serum levels of tumor marker CA19-9, CEA and CA15-3 were seen in patients with hepatitis ( P >0.05). In patients with hepatitis B, increase in CA125 were observed ( P =0.03). In hepatitis C patients, there was an increase in AFP levels ( P =0.03). The levels of AFP and CA125 markers were high in hepatitis C and hepatitis B, respectively. However, the increased levels were not seen is malignancy. Due to the small sample size, further study is necessary to find the reasons of the increase.

Spatial specificity of working memory representations in the early visual cortex.

Science.gov (United States)

Pratte, Michael S; Tong, Frank

2014-03-19

Recent fMRI decoding studies have demonstrated that early retinotopic visual areas exhibit similar patterns of activity during the perception of a stimulus and during the maintenance of that stimulus in working memory. These findings provide support for the sensory recruitment hypothesis that the mechanisms underlying perception serve as a foundation for visual working memory. However, a recent study by Ester, Serences, and Awh (2009) found that the orientation of a peripheral grating maintained in working memory could be classified from both the contralateral and ipsilateral regions of the primary visual cortex (V1), implying that, unlike perception, feature-specific information was maintained in a nonretinotopic manner. Here, we evaluated the hypothesis that early visual areas can maintain information in a spatially specific manner and will do so if the task encourages the binding of feature information to a specific location. To encourage reliance on spatially specific memory, our experiment required observers to retain the orientations of two laterally presented gratings. Multivariate pattern analysis revealed that the orientation of each remembered grating was classified more accurately based on activity patterns in the contralateral than in the ipsilateral regions of V1 and V2. In contrast, higher extrastriate areas exhibited similar levels of performance across the two hemispheres. A time-resolved analysis further indicated that the retinotopic specificity of the working memory representation in V1 and V2 was maintained throughout the retention interval. Our results suggest that early visual areas provide a cortical basis for actively maintaining information about the features and locations of stimuli in visual working memory.

Pion-nucleus forward scattering amplitudes at Δ(3,3) energies for π+---12C, 40Ca and 48Ca

International Nuclear Information System (INIS)

Dragoset, W.H. Jr.

1978-01-01

Using the LAMPF P 3 channel, small angle elastic cross sections and total cross sections were measured for π +- -- 12 C, 40 Ca and 48 Ca at incident pion kinetic energies spanning the energy region of the Δ(3,3) resonance. The sigma/sub EL/ experiment employed a spectrometer consisting of two magnets and six MWPC to measure scattering angles and momenta. For the sigma/sub T/ experiment six MWPC were positioned about the target in the beam to measure the deflection or absorption of the incident pions. Both experiments monitored the Jacobian cusp of the π → μ + ν decay to achieve absolute normalization. The two complementary data sets allowed the nuclear forward scattering amplitudes, f/sub N/(0), to be completely determined. The sigma/sub EL/ data were fit by a phenomenological small angle scattering model developed by Bethe and modified by West and Yennie. Due to the presence of nuclear-Coulomb interference in the elastic cross sections, both the magnitude and sign of Re f/sub N/ were determined by the fits. The Re f/sub N/ results were used in the sigma/sub T/ analysis to calculate corrections for the nuclear and nuclear-Coulomb interference amplitudes. Im f/sub N/ was calculated from the sigma/sub T/ results via the optical theorem. The overall self-consistencies of the data were checked by inserting IM f/sub N/ as a fixed parameter into the sigma/sub EL/ fits and comparing the resulting Re f/sub N/ to the original Re f/sub N/. It was determined that Re f/sub N/(0) has a zero near 180 MeV for both 12 C and 40 Ca. For 48 Ca, however, the Re f/sub N/ obtained by fitting with the West-Yennie formula was quite charge dependent and did not exhibit a zero in the energy range investigated. The differences in the 40 Ca, 48 Ca total cross sections were compared to a simple Kisslinger optical model calculation. The model indicated that the RMS neutron radius of 48 Ca exceeds the proton radius by 0.10 +- 0.06 fm

Retrieval of Brain Tumors by Adaptive Spatial Pooling and Fisher Vector Representation.

Science.gov (United States)

Cheng, Jun; Yang, Wei; Huang, Meiyan; Huang, Wei; Jiang, Jun; Zhou, Yujia; Yang, Ru; Zhao, Jie; Feng, Yanqiu; Feng, Qianjin; Chen, Wufan

2016-01-01

Content-based image retrieval (CBIR) techniques have currently gained increasing popularity in the medical field because they can use numerous and valuable archived images to support clinical decisions. In this paper, we concentrate on developing a CBIR system for retrieving brain tumors in T1-weighted contrast-enhanced MRI images. Specifically, when the user roughly outlines the tumor region of a query image, brain tumor images in the database of the same pathological type are expected to be returned. We propose a novel feature extraction framework to improve the retrieval performance. The proposed framework consists of three steps. First, we augment the tumor region and use the augmented tumor region as the region of interest to incorporate informative contextual information. Second, the augmented tumor region is split into subregions by an adaptive spatial division method based on intensity orders; within each subregion, we extract raw image patches as local features. Third, we apply the Fisher kernel framework to aggregate the local features of each subregion into a respective single vector representation and concatenate these per-subregion vector representations to obtain an image-level signature. After feature extraction, a closed-form metric learning algorithm is applied to measure the similarity between the query image and database images. Extensive experiments are conducted on a large dataset of 3604 images with three types of brain tumors, namely, meningiomas, gliomas, and pituitary tumors. The mean average precision can reach 94.68%. Experimental results demonstrate the power of the proposed algorithm against some related state-of-the-art methods on the same dataset.

Representational Machines

DEFF Research Database (Denmark)

Photography not only represents space. Space is produced photographically. Since its inception in the 19th century, photography has brought to light a vast array of represented subjects. Always situated in some spatial order, photographic representations have been operatively underpinned by social...... to the enterprises of the medium. This is the subject of Representational Machines: How photography enlists the workings of institutional technologies in search of establishing new iconic and social spaces. Together, the contributions to this edited volume span historical epochs, social environments, technological...... possibilities, and genre distinctions. Presenting several distinct ways of producing space photographically, this book opens a new and important field of inquiry for photography research....

Relationship between the Ca/P ratio of hydroxyapatite thin films and the spatial energy distribution of the ablation laser in pulsed laser deposition

NARCIS (Netherlands)

Nishikawa, H.; Hasegawa, T; Miyake, A.; Tashiro, Y.; Hashimoto, Y.; Blank, David H.A.; Rijnders, Augustinus J.H.M.

2016-01-01

Variation of the Ca/P ratio in hydroxyapatite (Ca10(PO4)6(OH)2) thin films was studied in relation to the spot size of the ablation laser for two different spatial energy distributions in pulsed laser deposition. One energy distribution is the defocus method with a raw distribution and the other is

Effects of induced Na+/Ca2+ exchanger overexpression on the spatial distribution of L-type Ca2+ channels and junctophilin-2 in pressure-overloaded hearts.

Science.gov (United States)

Ujihara, Yoshihiro; Mohri, Satoshi; Katanosaka, Yuki

2016-11-25

The Na + /Ca 2+ exchanger 1 (NCX1) is an essential Ca 2+ efflux system in cardiomyocytes. Although NCX1 is distributed throughout the sarcolemma, a subpopulation of NCX1 is localized to transverse (T)-tubules. There is growing evidence that T-tubule disorganization is a causal event that shifts the transition from hypertrophy to heart failure (HF). However, the detailed molecular mechanisms have not been clarified. Previously, we showed that induced NCX1 expression in pressure-overloaded hearts attenuates defective excitation-contraction coupling and HF progression. Here, we examined the effects of induced NCX1 overexpression on the spatial distribution of L-type Ca 2+ channels (LTCCs) and junctophilin-2 (JP2), a structural protein that connects the T-tubule and sarcoplasmic reticulum membrane, in pressure-overloaded hearts. Quantitative analysis showed that the regularity of NCX1 localization was significantly decreased at 8 weeks after transverse aortic constriction (TAC)-surgery; however, T-tubule organization and the regularities of LTCC and JP2 immunofluorescent signals were maintained at this time point. These observations demonstrated that release of NCX1 from the T-tubule area occurred before the onset of T-tubule disorganization and LTCC and JP2 mislocalization. Moreover, induced NCX1 overexpression at 8 weeks post-TAC not only recovered NCX1 regularity but also prevented the decrease in LTCC and JP2 regularities at 16 weeks post-TAC. These results suggested that NCX1 may play an important role in the proper spatial distribution of LTCC and JP2 in T-tubules in the context of pressure-overloading. Copyright © 2016 Elsevier Inc. All rights reserved.

Spin glass properties of Y0.7Ca0.3MnO3 and Th0.35Ba0.37Ca0.28MnO3

Science.gov (United States)

Sedmidubský, D.; Hejtmánek, J.; Maryško, M.; Jirák, Z.; Hardy, V.; Martin, C.

2002-05-01

Two perovskite manganites with the same nominal concentration of Mn4+ have been studied by the magnetic susceptibility and specific heat measurements: the Y0.7Ca0.3MnO3 single crystal (YCa) with low tolerance factor and negligible ionic radii variance and the Th0.35Ba0.37Ca0.28MnO3 (ThBaCa) ceramics with favorable tolerance factor but huge substitution induced disorder. Both systems were found to possess an insulating ground state with activated conductivity. The ac susceptibility data exhibit a frequency dependent peak at Tsg=32 K for YCa and Tsg=43 K for ThBaCa. The Cole-Cole analysis revealed a sharper than exponential increase of the relaxation time for the former sample while almost linear slowly growing characteristics below Tsg were observed for the latter one. Using the heat capacity curves, the magnetic contribution was separated and magnetic peaks with typical linear on-set tails were obtained. This observation and the abovementioned characteristics are all indicative of spin or cluster glass character. The necessary magnetic frustration is here induced by a considerable tilting of MnO6 octahedra and deformation of Mn-O bonds which occur in a cooperative manner for YCa and locally for ThBaCa.

Effect of Eu{sup 3+} doping on the structural and photoluminescence properties of cubic CaCO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Gao, Yan; Sun, Yidi; Zou, Haifeng; Sheng, Ye; Zhou, Xiuqing; Zhang, Bowen; Zhou, Bing, E-mail: zhoubing@jlu.edu.cn

2016-01-15

Graphical abstract: - Highlights: • The doping of Eu{sup 3+} ions decreased the size of CaCO{sub 3} nanoparticles. • The doping of Eu{sup 3+} ions brought about the change of CaCO{sub 3}'s optical bandgap. • Multiple sites of Eu{sup 3+} in CaCO{sub 3} nanocrystals have been identified. - Abstract: CaCO{sub 3}:xEu{sup 3+} (x = 0, 0.010, 0.015, 0.020, and 0.025) cubic nanoparticles were synthesized by carbonation method. The powder XRD patterns and SEM images of the CaCO{sub 3}:xEu{sup 3+} nanoparticles demonstrate that both the crystalline sizes and average particle sizes of synthesized samples decreased with the increase of Eu{sup 3+} content until x = 0.020. Kubelka–Munk plots and bandgap energy estimation indicate that the doping of Eu{sup 3+} ions changed optical bandgap of CaCO{sub 3}. Photoluminescence (PL) spectra show that the PL intensity of the CaCO{sub 3}:xEu{sup 3+} nanoparticles was enhanced with the increase of Eu{sup 3+} content in cubic CaCO{sub 3}:xEu{sup 3+}, and concentration quenching occurred when Eu{sup 3+} concentration exceeded 2.0 mol%. In addition, the doped sites of Eu{sup 3+} in CaCO{sub 3} crystalline were identified by the site-selective spectroscopy and decay curves.

Structure of the CaMKIIdelta/calmodulin complex reveals the molecular mechanism of CaMKII kinase activation.

Directory of Open Access Journals (Sweden)

Peter Rellos

2010-07-01

Full Text Available Long-term potentiation (LTP, a long-lasting enhancement in communication between neurons, is considered to be the major cellular mechanism underlying learning and memory. LTP triggers high-frequency calcium pulses that result in the activation of Calcium/Calmodulin (CaM-dependent kinase II (CaMKII. CaMKII acts as a molecular switch because it remains active for a long time after the return to basal calcium levels, which is a unique property required for CaMKII function. Here we describe the crystal structure of the human CaMKIIdelta/Ca2+/CaM complex, structures of all four human CaMKII catalytic domains in their autoinhibited states, as well as structures of human CaMKII oligomerization domains in their tetradecameric and physiological dodecameric states. All four autoinhibited human CaMKIIs were monomeric in the determined crystal structures but associated weakly in solution. In the CaMKIIdelta/Ca2+/CaM complex, the inhibitory region adopted an extended conformation and interacted with an adjacent catalytic domain positioning T287 into the active site of the interacting protomer. Comparisons with autoinhibited CaMKII structures showed that binding of calmodulin leads to the rearrangement of residues in the active site to a conformation suitable for ATP binding and to the closure of the binding groove for the autoinhibitory helix by helix alphaD. The structural data, together with biophysical interaction studies, reveals the mechanism of CaMKII activation by calmodulin and explains many of the unique regulatory properties of these two essential signaling molecules.This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3-D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the Web plugin are available in Text S1.

Teacher spatial skills are linked to differences in geometry instruction.

Science.gov (United States)

Otumfuor, Beryl Ann; Carr, Martha

2017-12-01

Spatial skills have been linked to better performance in mathematics. The purpose of this study was to examine the relationship between teacher spatial skills and their instruction, including teacher content and pedagogical knowledge, use of pictorial representations, and use of gestures during geometry instruction. Fifty-six middle school teachers participated in the study. The teachers were administered spatial measures of mental rotations and spatial visualization. Next, a single geometry class was videotaped. Correlational analyses revealed that spatial skills significantly correlate with teacher's use of representational gestures and content and pedagogical knowledge during instruction of geometry. Spatial skills did not independently correlate with the use of pointing gestures or the use of pictorial representations. However, an interaction term between spatial skills and content and pedagogical knowledge did correlate significantly with the use of pictorial representations. Teacher experience as measured by the number of years of teaching and highest degree did not appear to affect the relationships among the variables with the exception of the relationship between spatial skills and teacher content and pedagogical knowledge. Teachers with better spatial skills are also likely to use representational gestures and to show better content and pedagogical knowledge during instruction. Spatial skills predict pictorial representation use only as a function of content and pedagogical knowledge. © 2017 The British Psychological Society.

Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single crystals

International Nuclear Information System (INIS)

Haberkorn, N.; Larregola, S.; Franco, D.; Nieva, G.

2009-01-01

We present a study of the magnetic properties of Gd 2/3 Ca 1/3 MnO 3 single crystals at low temperatures, showing that this material behaves as an inhomogeneous ferrimagnet. In addition to small saturation magnetization at 5 K, we have found history dependent effects in the magnetization and the presence of exchange bias. These features are compatible with microscopic phase separation in the clean Gd 2/3 Ca 1/3 MnO 3 system studied

Vision and the representation of the surroundings in spatial memory

Science.gov (United States)

Tatler, Benjamin W.; Land, Michael F.

2011-01-01

One of the paradoxes of vision is that the world as it appears to us and the image on the retina at any moment are not much like each other. The visual world seems to be extensive and continuous across time. However, the manner in which we sample the visual environment is neither extensive nor continuous. How does the brain reconcile these differences? Here, we consider existing evidence from both static and dynamic viewing paradigms together with the logical requirements of any representational scheme that would be able to support active behaviour. While static scene viewing paradigms favour extensive, but perhaps abstracted, memory representations, dynamic settings suggest sparser and task-selective representation. We suggest that in dynamic settings where movement within extended environments is required to complete a task, the combination of visual input, egocentric and allocentric representations work together to allow efficient behaviour. The egocentric model serves as a coding scheme in which actions can be planned, but also offers a potential means of providing the perceptual stability that we experience. PMID:21242146

Vision and the representation of the surroundings in spatial memory.

Science.gov (United States)

Tatler, Benjamin W; Land, Michael F

2011-02-27

One of the paradoxes of vision is that the world as it appears to us and the image on the retina at any moment are not much like each other. The visual world seems to be extensive and continuous across time. However, the manner in which we sample the visual environment is neither extensive nor continuous. How does the brain reconcile these differences? Here, we consider existing evidence from both static and dynamic viewing paradigms together with the logical requirements of any representational scheme that would be able to support active behaviour. While static scene viewing paradigms favour extensive, but perhaps abstracted, memory representations, dynamic settings suggest sparser and task-selective representation. We suggest that in dynamic settings where movement within extended environments is required to complete a task, the combination of visual input, egocentric and allocentric representations work together to allow efficient behaviour. The egocentric model serves as a coding scheme in which actions can be planned, but also offers a potential means of providing the perceptual stability that we experience.

Photoluminescence properties of Eu(3+)/ Sm(3+) activated CaZr4(PO4)6 phosphors.

Science.gov (United States)

Nair, Govind B; Dhoble, S J

2016-09-01

Solid state reaction method was employed for the synthesis of a series of CaZr4(PO4)6: Eu(3+)/Sm(3+) phosphors. The red-emitting CaZr4(PO4)6:Eu(3+) phosphors can be efficiently excited at 396 nm and thereby, exhibit a strong red luminescence predominantly corresponding to the electric dipole transition at 615 nm. Under 405 nm excitation, CaZr4(PO4)6:Sm(3+) phosphors display orange emission with color temperatures approximately around 2200 K. The acquired results reveal that CaZr4(PO4)6: RE(3+) (RE = Eu, Sm) phosphors could be potential candidates for red and orange emitting phosphor, respectively, for UV/blue-pump LEDs.

Synthesis and luminescence enhancement of CaTiO{sub 3}:Bi{sup 3+} yellow phosphor by codoping Al{sup 3+}/B{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Cao, Renping, E-mail: jxcrp@163.com; Fu, Ting; Xu, Haidong; Luo, Wenjie; Peng, Dedong; Chen, Zhiquan; Fu, Jingwei

2016-07-25

CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors are synthesized by solid-state reaction method in air. With excitation 272 and 320 nm, broad PL band peaking at 555 nm with full width at half maximum ∼200 nm is observed in the range of 400–800 nm due to the {sup 3}P{sub 1,0} → {sup 1}S{sub 0} transitions of Bi{sup 3+} ion. PLE spectrum monitored at 555 nm contains two PLE band peaking at ∼272 and 320 nm within the range 230–420 nm owing to metal-to-metal charge-transfer and {sup 1}S{sub 0} → {sup 3}P{sub 1} transition of Bi{sup 3+} ion, respectively. The optimal Bi{sup 3+} doping concentration in CaTiO{sub 3}:Bi{sup 3+} phosphor is about 0.5 mol%. Luminescence properties of CaTiO{sub 3}:Bi{sup 3+} phosphor may be improved obviously by co-doping Al{sup 3+}/B{sup 3+} ions, and its emission intensity can be enhanced 13–15 times after Al{sup 3+} ion is co-doped. Luminous mechanism of CaTiO{sub 3}:Bi{sup 3+} phosphor is analyzed by energy level diagram of Bi{sup 3+} ion. Decay curve and time-resolved spectra confirm that only a single type of Bi{sup 3+} luminescence center exists in CaTiO{sub 3}:Bi{sup 3+} phosphor. - Graphical abstract: PL spectra of CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors and the corresponding pictures under 365 nm UV lamp. - Highlights: • CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors are synthesized by solid-state reaction in air. • Broadband emission with FWHM ∼200 nm is observed within the range 400–800 nm. • Luminescence properties of CaTiO{sub 3}:Bi{sup 3+} phosphor can be improved by codoping Al{sup 3+}/B{sup 3+} ions. • PL intensity of CaTiO{sub 3}:Bi{sup 3+} phosphor can be enhanced 13–15 times after Al{sup 3+} ion is codoped.

High-pressure compressibility and vibrational properties of (Ca,Mn)CO ₃

Energy Technology Data Exchange (ETDEWEB)

Liu, Jin; Caracas, Razvan; Fan, Dawei; Bobocioiu, Ema; Zhang, Dongzhou; Mao, Wendy L.

2016-12-01

Knowledge of potential carbon carriers such as carbonates is critical for our understanding of the deep-carbon cycle and related geological processes within the planet. Here we investigated the high-pressure behavior of (Ca,Mn)CO₃ up to 75 GPa by synchrotron single-crystal X-ray diffraction, laser Raman spectroscopy, and theoretical calculations. MnCO₃-rich carbonate underwent a structural phase transition from the CaCO₃-I structure into the CaCO₃-VI structure at 45–48 GPa, while CaCO₃-rich carbonate transformed into CaCO₃-III and CaCO₃-VI at approximately 2 and 15 GPa, respectively. The equation of state and vibrational properties of MnCO₃-rich and CaCO₃-rich carbonates changed dramatically across the phase transition. The CaCO₃-VI-structured CaCO₃-rich and MnCO₃-rich carbonates were stable at room temperature up to at least 53 and 75 GPa, respectively. The addition of smaller cations (e.g., Mn²⁺, Mg²⁺, and Fe²⁺) can enlarge the stability field of the CaCO₃-I phase as well as increase the pressure of the structural transition into the CaCO₃-VI phase.

Mg/Ca- Δ CO3porewater2- -temperature calibration for Globobulimina spp.: A sensitive paleothermometer for deep-sea temperature reconstruction

Science.gov (United States)

Weldeab, Syee; Arce, Adam; Kasten, Sabine

2016-03-01

Existing benthic foraminiferal Mg/Ca-temperature calibrations are surrounded by substantial uncertainties mainly due to low temperature sensitivity of Mg/Ca in most benthic foraminifers and the effect of carbonate ion concentration on benthic foraminiferal Mg/Ca. Here we present Mg/Ca analysis of Rose Bengal stained and exceptionally well-preserved tests of the infaunal benthic foraminifer Globobulimina spp. from 39 eastern equatorial Atlantic core top samples. Mg/Ca in Globobulimina spp. varies between 2.5 mmol/mol and 9.1 mmol/mol corresponding to bottom water temperatures (BWT) between 1.8 °C and 19.1 °C and Δ CO3pore water2- between 33.7 ± 4 and - 34.3 ± 4 μmol /kg in sediment depths between 1 and 10 cm. Mg/Ca and BWT are linearly correlated with a best fit of Mg/Ca [mmol/mol] = (0.36 ± 0.02) * BWT [°C] + 2.22 ± 0.19 (r2 = 0.92, p-value: 11 *10-20, and n = 39). Using total alkalinity and pH data of pore water samples from 64 Atlantic multi-corer sites, we obtained Δ CO3pore water2- data from the depth habitat range of Globobulimina spp. (≥1 cm ≤ 10 cm below sediment surface). We show that Δ CO3pore waterSUP>2- is significantly lower than and linearly co-varies with the ΔCO2-3 of the overlying bottom water: Δ CO3pore water2- = (0.67 ± 0.05) * Δ CO3bottom water2- - (39.84 ± 1.98); r2 = 0.75, p-value: 6 *10-20, n = 64. We found a Mg/Ca sensitivity of 0.009 ± 0.0044 mmol /mol per μmol/kg Δ CO3pore water2- and Mg/Ca temperature sensitivity of 0.32 ± 0.06 mmol /mol / °C after a correction for the Δ CO3pore water2- effect. This study provides a robust Mg/Ca-temperature calibration, highlights that Δ CO3pore water2- is spatially and most likely temporally variable, and contradicts the notion that infaunal foraminiferal Mg/Ca is relatively immune from ΔCO2-3 changes in the overlying bottom water. Furthermore, comparison of down core Mg/Ca data of Cibicides pachyderma and Globobulimina spp. demonstrates that the high temperature sensitivity of

Properties of closed 3-braids and braid representations of links

CERN Document Server

Stoimenow, Alexander

2017-01-01

This book studies diverse aspects of braid representations via knots and links. Complete classification results are illustrated for several properties through Xu’s normal 3-braid form and the Hecke algebra representation theory of link polynomials developed by Jones. Topological link types are identified within closures of 3-braids which have a given Alexander or Jones polynomial. Further classifications of knots and links arising by the closure of 3-braids are given, and new results about 4-braids are part of the work. Written with knot theorists, topologists,and graduate students in mind, this book features the identification and analysis of effective techniques for diagrammatic examples with unexpected properties.

Synthesis and luminescent properties of CaCO3:Eu3+@SiO2 phosphors with core-shell structure

Science.gov (United States)

Liu, Min; Kang, Ming; Chen, Kexu; Mou, Yongren; Sun, Rong

2018-03-01

Integrating the processes of preparation of CaCO3:Eu3+ and its surface-coating, core-shell structured CaCO3:Eu3+@SiO2 phosphors with red emission were synthesized by the carbonation method and surface precipitation procedure using sodium silicate as silica source. The phase structure, thermal stability, morphology and luminescent property of the as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectrum, thermal analysis, field-emission scanning electron microscopy, transmission electron microscope and photoluminescence spectra. The experimental results show that Eu3+ ions as the luminescence center are divided into two types: one is at the surface of the CaCO3 and the other inhabits the site of Ca2+. For CaCO3:Eu3+@SiO2 phosphors, the SiO2 layers are continuously coated on the surface of CaCO3:Eu3+ and show a typical core-shell structure. After coated with SiO2 layer, the luminous intensity and the compatibility with the rubber matrix increase greatly. Additionally, the luminous intensity increases with the increasing of Eu3+ ions concentration in CaCO3 core and concentration quenching occurs when Eu3+ ions concentration exceeds 7.0 mol%, while it is 5.0 mol% for CaCO3:Eu3+ phosphors. Therefore, preparation of CaCO3:Eu3+@SiO2 phosphors can not only simplify the experimental process through integrating the preparation of CaCO3:Eu3+ and SiO2 layer, but also effectively increase the luminous intensities of CaCO3:Eu3+ phosphors. The as-obtained phosphors may have potential applications in the fields of optical materials and functional polymer composite materials, such as plastics and rubbers.

The diagnostic value of determination of serum GOLPH3 associated with CA125, CA19.9 in patients with ovarian cancer.

Science.gov (United States)

Fan, H-Y; Duan, D-M; Liu, Y-F

2017-09-01

To evaluate the value of three tumor markers serum Golgi phosphoprotein-3 (GOLPH3), cancer antigen 125 (CA125) and cancer antigen 19-9 (CA19.9) in the diagnosis and postoperative evaluation of ovarian cancer by detecting these three markers. A total of 187 patients were studied and included in the ovarian cancer group, benign pelvic mass group, and the normal control group. The levels of serum Golgi phosphoprotein-3 (GOLPH3), cancer antigen 125 (CA125) and cancer antigen 199 (CA19.9) were detected, respectively, and their effects on the diagnosis, evaluation, pathology typing and staging of ovarian cancer were measured. The sensitivity of the detection of ovarian cancer by GOLPH3 combined with CA125 and CA19.9 was higher than that by a single marker (pserum GOLPH3 in patients with serous and endometrioid carcinoma was significantly higher than that in patients with mucinous carcinoma, clear-cell carcinoma and germ cell tumor (pserum GOLPH3 level between patients with ovarian malignancies at stage III-IV and those at stage I-II (p>0.05). The levels of serum GOLPH3, CA125 and CA19.9 in patients with ovarian malignancies after surgery were significantly lower than those before surgery (p<0.05). The combined detection by GOLPH3, CA125, and CA19.9 may improve the diagnosis rate of ovarian epithelial cancer. GOLPH3, as a new ovarian cancer tumor marker used in clinical diagnosis, is expected to become an important indicator for the early diagnosis of ovarian cancer and the determination of clinical surgery efficacy.

Coastline Zones Identification and 3D Coastal Mapping Using UAV Spatial Data

Directory of Open Access Journals (Sweden)

Apostolos Papakonstantinou

2016-05-01

Full Text Available Spatial data acquisition is a critical process for the identification of the coastline and coastal zones for scientists involved in the study of coastal morphology. The availability of very high-resolution digital surface models (DSMs and orthophoto maps is of increasing interest to all scientists, especially those monitoring small variations in the earth’s surface, such as coastline morphology. In this article, we present a methodology to acquire and process high resolution data for coastal zones acquired by a vertical take off and landing (VTOL unmanned aerial vehicle (UAV attached to a small commercial camera. The proposed methodology integrated computer vision algorithms for 3D representation with image processing techniques for analysis. The computer vision algorithms used the structure from motion (SfM approach while the image processing techniques used the geographic object-based image analysis (GEOBIA with fuzzy classification. The SfM pipeline was used to construct the DSMs and orthophotos with a measurement precision in the order of centimeters. Consequently, GEOBIA was used to create objects by grouping pixels that had the same spectral characteristics together and extracting statistical features from them. The objects produced were classified by fuzzy classification using the statistical features as input. The classification output classes included beach composition (sand, rubble, and rocks and sub-surface classes (seagrass, sand, algae, and rocks. The methodology was applied to two case studies of coastal areas with different compositions: a sandy beach with a large face and a rubble beach with a small face. Both are threatened by beach erosion and have been degraded by the action of sea storms. Results show that the coastline, which is the low limit of the swash zone, was detected successfully by both the 3D representations and the image classifications. Furthermore, several traces representing previous sea states were

Age-dependent changes in diastolic Ca2+ and Na+ concentrations in dystrophic cardiomyopathy: Role of Ca2+ entry and IP3

International Nuclear Information System (INIS)

Mijares, Alfredo; Altamirano, Francisco; Kolster, Juan; Adams, José A.; López, José R.

2014-01-01

Highlights: • Age-dependent increase in [Ca 2+ ] d and [Na + ] d in mdx cardiomyocytes. • Gadolinium significantly reduced both [Ca 2+ ] d and [Na + ] d at all ages. • IP 3 -pathway inhibition reduced cations concentrations in dystrophic cardiomyocytes. - Abstract: Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca 2+ concentration ([Ca 2+ ] d ) and diastolic Na + concentration ([Na + ] d ) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd 3+ )-sensitive Ca 2+ entry and inositol triphosphate (IP 3 ) signaling pathways in abnormal [Ca 2+ ] d and [Na + ] d were investigated. Our results showed an age-dependent increase in both [Ca 2+ ] d and [Na + ] d in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd 3+ treatment significantly reduced both [Ca 2+ ] d and [Na + ] d at all ages. In addition, blockade of the IP 3 -pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd 3+ normalized both [Ca 2+ ] d and [Na + ] d at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca 2+ and Na + overload mediated at least in part by enhanced Ca 2+ entry through Gd 3+ sensitive transient receptor potential channels (TRPC), and by IP 3 receptors

Pathways for Energization of Ca in Mercury's Exosphere

Science.gov (United States)

Killen, Rosemary M.

2015-01-01

We investigate the possible pathways to produce the extreme energy observed in the calcium exosphere of Mercury. Any mechanism must explain the facts that Ca in Mercury's exosphere is extremely hot, that it is seen almost exclusively on the dawnside of the planet, and that its content varies seasonally, not sporadically. Simple diatomic molecules or their clusters are considered, focusing on calcium oxides while acknowledging that Ca sulfides may also be the precursor molecules. We first discuss impact vaporization to justify the assumption that CaO and Ca-oxide clusters are expected from impacts on Mercury. Then we discuss processes by which the atomic Ca is energized to a 70,000 K gas. The processes considered are (1) electron-impact dissociation of CaO molecules, (2) spontaneous dissociation of Ca-bearing molecules following impact vaporization, (3) shock-induced dissociative ionization, (4) photodissociation and (5) sputtering. We conclude that electron-impact dissociation cannot produce the required abundance of Ca, and sputtering cannot reproduce the observed spatial and temporal variation that is measured. Spontaneous dissociation is unlikely to result in the high energy that is seen. Of the two remaining processes, shock induced dissociative ionization produces the required energy and comes close to producing the required abundance, but rates are highly dependent on the incoming velocity distribution of the impactors. Photodissociation probably can produce the required abundance of Ca, but simulations show that photodissociation cannot reproduce the observed spatial distribution.

Microstructure and electric characteristics of AETiO3 (AE=Mg, Ca, Sr doped CaCu3Ti4O12 thin films prepared by the sol–gel method

Directory of Open Access Journals (Sweden)

Dong Xu

2015-10-01

Full Text Available This paper focuses on the effects of alkline-earth metal titante AETiO3 (AE=Mg, Ca, Sr doping on the microstructure and electric characteristics of CaCu3Ti4O12 thin films prepared by the sol–gel method. The results showed that the grain size of CCTO thin films could be increased by MgTiO3 doping. The movement of the grain boundaries was impeded by the second phases of CaTiO3 and SrTiO3 concentrating at grain boundaries in CaTiO3 and SrTiO3 doped CCTO thin films. Rapid ascent of dielectric constant could be observed in 0.1Mg TiO3 doped CCTO thin films, which was almost as three times high as pure CCTO thin film and the descent of the dielectric loss at low frequency could also be observed. In addition, the nonlinear coefficient (α, threshold voltage (VT and leakage current (IL of AETiO3 doped CCTO thin films (AE=Mg, Ca, Sr showed different variation with the increasing content of the MgTiO3, CaTiO3 and SrTiO3.

Teratological studies of DTPA-CaNa3, DTPA-ZnNa3 and quinamic acid in mice

International Nuclear Information System (INIS)

Luo Meichu; Ruan Tianming; Tong Shungao

1989-01-01

DTPA-CaNa 3 , DTPA-ZnNa 3 and quinamic acid are effective chelating agents for removing actinide elements from the body. In this experiment, different doses of DTPA-CaNa 3 , DTPA-ZnNa 3 and quinamic acid were given to mice on gestation days 6-10. Eight groups of mice received 0.8 and 2.0 mM/kg of DTPA-CaNa 3 , 3.8, 7.6, and 11.4 mM/kg of DTPA-ZnNa 3 and 0.42, 2.1, and 4.2 mM/kg of quinamic acid. Hypetonic saline and isotonic saline were given to two control groups. DTPA-CaNa 3 and quinamidic acid were found to be much more toxic to fetus of mice than DTPA-ZnNa 3 . When the doses of DTPA-CaMa 3 and quinamidic acid were 20 times higher than the human dose, the number of resorbed fetus was increased and the number and weight of live fetus were reduced. The result of injection with 7.6 mM/kg (200 times of human dose)DTPA-ZnNa 3 and that of injection with isotonic saline are the same. Therefore, we suggest that the DTPA-CaNa 3 and quinamidic acid should not be given to pregnant woman, if chelation therapy is needed, while the much safer DTPA-ZnNa 3 could be used

caCORE version 3: Implementation of a model driven, service-oriented architecture for semantic interoperability

OpenAIRE

Komatsoulis, George A.; Warzel, Denise B.; Hartel, Frank W.; Shanbhag, Krishnakant; Chilukuri, Ram; Fragoso, Gilberto; de Coronado, Sherri; Reeves, Dianne M.; Hadfield, Jillaine B.; Ludet, Christophe; Covitz, Peter A.

2007-01-01

One of the requirements for a federated information system is interoperability, the ability of one computer system to access and use the resources of another system. This feature is particularly important in biomedical research systems, which need to coordinate a variety of disparate types of data. In order to meet this need, the National Cancer Institute Center for Bioinformatics (NCICB) has created the cancer Common Ontologic Representation Environment (caCORE), an interoperability infrastr...

Luminescent properties and energy transfer of Gd{sup 3+}/Eu{sup 3+} co-doped cubic CaCO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sun, Yidi; Zou, Haifeng; Zhang, Bowen; Zhou, Xiuqing; Song, Yanhua; Zheng, Keyan [College of Chemistry, Jilin University, Changchun 130012 (China); Shi, Zhan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Sheng, Ye, E-mail: shengye@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

2016-10-15

Gd{sup 3+} and Eu{sup 3+} ions co-doped CaCO{sub 3} nanoparticles have been successfully synthesized via carbonization method. The emission spectra of co-doped CaCO{sub 3} phosphors in the range of VUV–vis spectral were studied. The results reveal that the co-doped CaCO{sub 3} phosphors show intense red emission in the VUV range because of the Gd{sup 3+} ions as sensitizers. The energy transfer process from Gd{sup 3+} to Eu{sup 3+} in CaCO{sub 3}:Gd{sup 3+}/Eu{sup 3+} phosphors was investigated and discussed in terms of the luminescence spectra and the decay curves, which demonstrated that the energy transfer of Gd{sup 3+}→Eu{sup 3+} is efficient. The mechanism of energy transfer from Gd{sup 3+} to Eu{sup 3+} is a resonant transfer, in which electric dipole–dipole interaction plays a leading role. Furthermore, the effect of doping concentration of Eu{sup 3+} ions on the energy transfer efficiency was also investigated. From the photoluminescence (PL) spectra, it was also found that the incorporation of Na{sup +} ions into CaCO{sub 3}:Gd{sup 3+}/Eu{sup 3+} could lead to a remarkable increase of luminescent intensity due to the charge compensation.

Novel method of generation of Ca(HCO32 and CaCO3 aerosols and first determination of hygroscopic and cloud condensation nuclei activation properties

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A. Trimborn

2010-09-01

Full Text Available Atmospheric mineral aerosols contain CaCO3 as a reactive component. A novel method to produce CaCO3 aerosol was developed by spraying Ca(HCO32 solution, which was generated from a CaCO3 suspension and CO2. By aerosol mass spectrometry the freshly sprayed and dried aerosol was characterized to consist of pure Ca(HCO32 which under annealing in a tube furnace transformed into CaCO3. Transmission Electron Microscopy demonstrated that the particles produced were spherical. The method was able to generate aerosol of sufficient concentration and proper size for the study of physiochemical properties and investigations of heterogeneous reactions of mineral aerosol. The dried Ca(HCO32 particles were somewhat more hygroscopic than CaCO3 particles. However, during humidification a restructuring took place and ∼2/3 of the Ca(HCO32 was transformed to CaCO3. The mixed Ca(HCO32/CaCO3(s particles were insoluble with a growth factor of 1.03 at 95% (hygroscopicity parameter κ=0.011±0.007 relative humidity. This compares to a corresponding growth factor of 1.01 for CaCO3(s (κ=0.0016±0.0004. Mass spectrometric composition analysis, restructuring, and insolubility of the mixed particles suggested that solid Ca(HCO32(s was observed. This would be in contrast to the current belief that Ca(HCO32(s is thermodynamically instable. The CCN activity of Ca(HCO32(s aerosol (κ≈0.15 is remarkably higher than that of CaCO3 aerosol (κ=0.0019±0.0007 and less than that of Ca(NO32. The noticeable but limited solubility of Ca(HCO32 of ≈0.01 mol/l explains limited hygroscopic growth and good CCN activity. Experiments in the Large Jülich Aerosol Chamber indicated that Ca(HCO32(s could exist for several hours under dry atmospheric conditions. However, it was likely buried in a protective layer of CaCO3(s. We conclude that Ca(HCO32 may be formed in the atmosphere in cloud droplets of activated mineral dust by reaction of CaCO3 with CO2 and H2O. The presence of Ca(HCO32 and

Compound effect of CaCO3 and CaSO4·2H2O on the strength of steel slag: cement binding materials

International Nuclear Information System (INIS)

Qi, Liqian; Liu, Jiaxiang; Liu, Qian

2016-01-01

In this study, we replaced 30% of the cement with steel slag to prepare binding material; additionally, small amounts of CaCO 3 and CaSO 4 ·2H 2 O were added. This was done to study the compound effect of CaCO 3 and CaSO 4 ·2H 2 O on the strength of steel slag-cement binding materials. The hydration degree of the steel slag cementitious material was analyzed by XRD, TG and SEM. The results showed that the optimum proportions of CaCO 3 and CaSO 4 ·2H 2 O were 3% and 2%, respectively. Compared with the steel slag-cement binders without adding CaCO 3 and CaSO 4 ·2H 2 O, the compressive strength increased by 59.9% at 3 days and by 17.8% at 28 days. Acting as the nucleation matrix, CaCO 3 could accelerate the hydration of C 3 S. In addition, CaCO 3 was involved in the hydration reaction, generating a new hydration product, which could stably exist in a slurry. Meanwhile, CaSO 4 ·2H 2 O could increase the number of AFt. The compound effect of CaCO 3 and CaSO 4 ·2H 2 O enhanced the intensity of steel slag-cement binding materials and improved the whole hydration behavior. (author)

Semiconductor-metal transition in CaMO3-CaTiO2 (M-Ru,Ir) systems

International Nuclear Information System (INIS)

Lazarev, V.B.; Shaplygin, I.S.

1982-01-01

Properties of CaRusub(x)Tisub(1-x)Osub(3) and CaIsub(2x)Tisub(1-x)Osub(3) solid solutions were studied in the whole range of concentrations by the methods of X-ray diffraction, electric conductivity and magnetic susceptibility. It was ascertained that the transition of semiconductor-metal type proceeded in the both families of solid solutions at x approximately 0.77 and 0.85 respectively and was accompanied by the change of structural type of solid solutions

caCORE version 3: Implementation of a model driven, service-oriented architecture for semantic interoperability.

Science.gov (United States)

Komatsoulis, George A; Warzel, Denise B; Hartel, Francis W; Shanbhag, Krishnakant; Chilukuri, Ram; Fragoso, Gilberto; Coronado, Sherri de; Reeves, Dianne M; Hadfield, Jillaine B; Ludet, Christophe; Covitz, Peter A

2008-02-01

One of the requirements for a federated information system is interoperability, the ability of one computer system to access and use the resources of another system. This feature is particularly important in biomedical research systems, which need to coordinate a variety of disparate types of data. In order to meet this need, the National Cancer Institute Center for Bioinformatics (NCICB) has created the cancer Common Ontologic Representation Environment (caCORE), an interoperability infrastructure based on Model Driven Architecture. The caCORE infrastructure provides a mechanism to create interoperable biomedical information systems. Systems built using the caCORE paradigm address both aspects of interoperability: the ability to access data (syntactic interoperability) and understand the data once retrieved (semantic interoperability). This infrastructure consists of an integrated set of three major components: a controlled terminology service (Enterprise Vocabulary Services), a standards-based metadata repository (the cancer Data Standards Repository) and an information system with an Application Programming Interface (API) based on Domain Model Driven Architecture. This infrastructure is being leveraged to create a Semantic Service-Oriented Architecture (SSOA) for cancer research by the National Cancer Institute's cancer Biomedical Informatics Grid (caBIG).

Mutations in PIK3CA are infrequent in neuroblastoma

International Nuclear Information System (INIS)

Dam, Vincent; Morgan, Brian T; Mazanek, Pavel; Hogarty, Michael D

2006-01-01

Neuroblastoma is a frequently lethal pediatric cancer in which MYCN genomic amplification is highly correlated with aggressive disease. Deregulated MYC genes require co-operative lesions to foster tumourigenesis and both direct and indirect evidence support activated Ras signaling for this purpose in many cancers. Yet Ras genes and Braf, while often activated in cancer cells, are infrequent targets for activation in neuroblastoma. Recently, the Ras effector PIK3CA was shown to be activated in diverse human cancers. We therefore assessed PIK3CA for mutation in human neuroblastomas, as well as in neuroblastomas arising in transgenic mice with MYCN overexpressed in neural-crest tissues. In this murine model we additionally surveyed for Ras family and Braf mutations as these have not been previously reported. Sixty-nine human neuroblastomas (42 primary tumors and 27 cell lines) were sequenced for PIK3CA activating mutations within the C2, helical and kinase domain 'hot spots' where 80% of mutations cluster. Constitutional DNA was sequenced in cases with confirmed alterations to assess for germline or somatic acquisition. Additionally, Ras family members (Hras1, Kras2 and Nras) and the downstream effectors Pik3ca and Braf, were sequenced from twenty-five neuroblastomas arising in neuroblastoma-prone transgenic mice. We identified mutations in the PIK3CA gene in 2 of 69 human neuroblastomas (2.9%). Neither mutation (R524M and E982D) has been studied to date for effects on lipid kinase activity. Though both occurred in tumors with MYCN amplification the overall rate of PIK3CA mutations in MYCN amplified and single-copy tumors did not differ appreciably (2 of 31 versus 0 of 38, respectively). Further, no activating mutations were identified in a survey of Ras signal transduction genes (including Hras1, Kras2, Nras, Pik3ca, or Braf genes) in twenty-five neuroblastic tumors arising in the MYCN-initiated transgenic mouse model. These data suggest that activating

A role for CA3 in social recognition memory.

Science.gov (United States)

Chiang, Ming-Ching; Huang, Arthur J Y; Wintzer, Marie E; Ohshima, Toshio; McHugh, Thomas J

2018-02-02

Social recognition memory is crucial for survival across species, underlying the need to correctly identify conspecifics, mates and potential enemies. In humans the hippocampus is engaged in social and episodic memory, however the circuit mechanisms of social memory in rodent models has only recently come under scrutiny. Work in mice has established that the dorsal CA2 and ventral CA1 regions play critical roles, however a more comprehensive comparative analyses of the circuits and mechanisms required has not been reported. Here we employ conditional genetics to examine the differential contributions of the hippocampal subfields to social memory. We find that the deletion of NMDA receptor subunit 1 gene (NR1), which abolishes NMDA receptor synaptic plasticity, in CA3 pyramidal cells led to deficits in social memory; however, mice lacking the same gene in DG granule cells performed indistinguishable from controls. Further, we use conditional pharmacogenetic inhibition to demonstrate that activity in ventral, but not dorsal, CA3 is necessary for the encoding of a social memory. These findings demonstrated CA3 pyramidal cell plasticity and transmission contribute to the encoding of social stimuli and help further identify the distinct circuits underlying the role of the hippocampus in social memory. Copyright © 2018 Elsevier B.V. All rights reserved.

A new technique for the assessment of the 3D spatial distribution of the calcium/phosphorus ratio in bone apatite.

Science.gov (United States)

Hadjipanteli, A; Kourkoumelis, N; Fromme, P; Olivo, A; Huang, J; Speller, R

2013-11-01

The value and distribution of calcium/phosphorus (Ca/P) ratio in bone vary between healthy and osteoporotic bone. The purpose of this study was the development of a technique for the assessment of the 3D spatial distribution of Ca/P ratio in bone apatite, which could eventually be implemented through a conventional computed tomography (CT) system. A three-material mass-fraction decomposition CT dual energy analysis was optimized. The technique was validated using ten bone phantoms of different, known Ca/P ratio. Their measured average Ca/P ratio showed a mean/maximum deviation from the expected Ca/P ratio of 0.24/0.35. Additionally, three healthy and three inflammation-mediated osteoporotic (IMO) collagen-free rabbit tibia bone samples were assessed, providing promising preliminary results on real bone tissue. The average Ca/P ratios in all IMO samples (1.64-1.65) were found to be lower than in healthy samples (1.67-1.68). Osteoporotic regions in IMO samples were located using Ca/P ratio colour maps and Ca/P ratio values as low as 1.40 ± 0.26 were found. The low Ca/P ratio volume proportion in IMO samples (12.8%-13.9%) was found to be higher than in healthy (5.8%-8.3%) samples. A region growing technique showed a higher homogeneity of Ca/P ratio in healthy than in IMO bone samples.

A Method of Vector Map Multi-scale Representation Considering User Interest on Subdivision Gird

Directory of Open Access Journals (Sweden)

YU Tong

2016-12-01

Full Text Available Compared with the traditional spatial data model and method, global subdivision grid show a great advantage in the organization and expression of massive spatial data. In view of this, a method of vector map multi-scale representation considering user interest on subdivision gird is proposed. First, the spatial interest field is built using a large number POI data to describe the spatial distribution of the user interest in geographic information. Second, spatial factor is classified and graded, and its representation scale range can be determined. Finally, different levels of subdivision surfaces are divided based on GeoSOT subdivision theory, and the corresponding relation of subdivision level and scale is established. According to the user interest of subdivision surfaces, the spatial feature can be expressed in different degree of detail. It can realize multi-scale representation of spatial data based on user interest. The experimental results show that this method can not only satisfy general-to-detail and important-to-secondary space cognitive demands of users, but also achieve better multi-scale representation effect.

Efeitos de relações CaSO4/CaCO3 na mobilidade de nutrientes no solo e no crescimento do algodoeiro

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A. A. Silva

1998-09-01

Full Text Available O experimento, realizado em casa de vegetação no Departamento de Ciência do Solo da Universidade Federal de Lavras, teve por objetivo estudar o efeito de diferentes relações de CaSO4/CaCO3, que simulam o uso de gesso e calcário, na movimentação de nutrientes no solo e no crescimento do algodoeiro, cultivar IAC-20. As proporções de CaSO4/CaCO3 utilizadas foram: 0/100, 25/75, 50/50, 75/25 e 100/0, com base em peso equivalente, além de um tratamento-testemunha, sem aplicação de CaSO4 e CaCO3. Observou-se acentuada movimentação de cálcio e de sulfato em profundidade, como íons acompanhantes, com o aumento da relação CaSO4/CaCO3. Para o N-NO3- e Mg2+, ao contrário do N-NH4+ e K+, observou-se um acúmulo em profundidade, com a elevação da relação CaSO4/CaCO3. Neste estudo, o gesso teve pouco ou nenhum efeito sobre a acidez e Al trocável presentes nas camadas subsuperficiais. A produção de matéria seca do algodoeiro foi reduzida com o aumento da relação CaSO4/CaCO3, porém, quando comparada à do tratamento-testemunha, a aplicação de gesso aumentou-a significativamente, atestando o potencial de uso do gesso agrícola.

Preattentive representation of feature conjunctions for concurrent spatially distributed auditory objects.

Science.gov (United States)

Takegata, Rika; Brattico, Elvira; Tervaniemi, Mari; Varyagina, Olga; Näätänen, Risto; Winkler, István

2005-09-01

The role of attention in conjoining features of an object has been a topic of much debate. Studies using the mismatch negativity (MMN), an index of detecting acoustic deviance, suggested that the conjunctions of auditory features are preattentively represented in the brain. These studies, however, used sequentially presented sounds and thus are not directly comparable with visual studies of feature integration. Therefore, the current study presented an array of spatially distributed sounds to determine whether the auditory features of concurrent sounds are correctly conjoined without focal attention directed to the sounds. Two types of sounds differing from each other in timbre and pitch were repeatedly presented together while subjects were engaged in a visual n-back working-memory task and ignored the sounds. Occasional reversals of the frequent pitch-timbre combinations elicited MMNs of a very similar amplitude and latency irrespective of the task load. This result suggested preattentive integration of auditory features. However, performance in a subsequent target-search task with the same stimuli indicated the occurrence of illusory conjunctions. The discrepancy between the results obtained with and without focal attention suggests that illusory conjunctions may occur during voluntary access to the preattentively encoded object representations.

Chemical stability and defect formation in CaHfO3

KAUST Repository

Alay-E-Abbas, Syed Muhammad

2014-04-01

Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

Chemical stability and defect formation in CaHfO3

KAUST Repository

Alay-E-Abbas, Syed Muhammad; Nazir, Safdar; Mun Wong, Kin; Shaukat, Ali; Schwingenschlö gl, Udo

2014-01-01

Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

Cross-cultural differences in mental representations of time: evidence from an implicit nonlinguistic task.

Science.gov (United States)

Fuhrman, Orly; Boroditsky, Lera

2010-11-01

Across cultures people construct spatial representations of time. However, the particular spatial layouts created to represent time may differ across cultures. This paper examines whether people automatically access and use culturally specific spatial representations when reasoning about time. In Experiment 1, we asked Hebrew and English speakers to arrange pictures depicting temporal sequences of natural events, and to point to the hypothesized location of events relative to a reference point. In both tasks, English speakers (who read left to right) arranged temporal sequences to progress from left to right, whereas Hebrew speakers (who read right to left) arranged them from right to left, replicating previous work. In Experiments 2 and 3, we asked the participants to make rapid temporal order judgments about pairs of pictures presented one after the other (i.e., to decide whether the second picture showed a conceptually earlier or later time-point of an event than the first picture). Participants made responses using two adjacent keyboard keys. English speakers were faster to make "earlier" judgments when the "earlier" response needed to be made with the left response key than with the right response key. Hebrew speakers showed exactly the reverse pattern. Asking participants to use a space-time mapping inconsistent with the one suggested by writing direction in their language created interference, suggesting that participants were automatically creating writing-direction consistent spatial representations in the course of their normal temporal reasoning. It appears that people automatically access culturally specific spatial representations when making temporal judgments even in nonlinguistic tasks. Copyright © 2010 Cognitive Science Society, Inc.

Selection of spatial reference frames depends on task's demands

Directory of Open Access Journals (Sweden)

Greeshma Sharma

2016-12-01

Full Text Available Spatial reference frames (SRF are the means of representing spatial relations or locations either in an egocentric coordinate system (centred on navigator or in an allocentric coordinate system (Centred on object. It is necessary to understand when and how spatial representation switches between allocentric and egocentric reference frames in context to spatial tasks. The objective of this study was to explore if the elementary spatial representation does exist, whether it would remain consistent or change under the influence of a task's demand. Also, we explored how the SRF would assist if the environment is enriched with landmarks, having multiple routes for wayfinding. The results showed that the switching of SRF depends not only on the default representation but also on a task's demand. They also demonstrated that participants who were using allocentric representation performed better in the presence of landmarks.

Aspirin exerts high anti-cancer activity in PIK3CA-mutant colon cancer cells.

Science.gov (United States)

Gu, Mancang; Nishihara, Reiko; Chen, Yang; Li, Wanwan; Shi, Yan; Masugi, Yohei; Hamada, Tsuyoshi; Kosumi, Keisuke; Liu, Li; da Silva, Annacarolina; Nowak, Jonathan A; Twombly, Tyler; Du, Chunxia; Koh, Hideo; Li, Wenbin; Meyerhardt, Jeffrey A; Wolpin, Brian M; Giannakis, Marios; Aguirre, Andrew J; Bass, Adam J; Drew, David A; Chan, Andrew T; Fuchs, Charles S; Qian, Zhi Rong; Ogino, Shuji

2017-10-20

Evidence suggests that nonsteroidal anti-inflammatory drug aspirin (acetylsalicylic acid) may improve patient survival in PIK3CA -mutant colorectal carcinoma, but not in PIK3CA -wild-type carcinoma. However, whether aspirin directly influences the viability of PIK3CA -mutant colon cancer cells is poorly understood. We conducted in vitro experiments to test our hypothesis that the anti-proliferative activity of aspirin might be stronger for PIK3CA -mutant colon cancer cells than for PIK3CA -wild-type colon cancer cells. We measured the anti-proliferative effect of aspirin at physiologic concentrations in seven PIK3CA -mutant and six PIK3CA -wild-type human colon cancer cell lines. After exposure to aspirin, the apoptotic index and cell cycle phase of colon cancer cells were assessed. In addition, the effect of aspirin was examined in parental SW48 cells and SW48 cell clones with individual knock-in PIK3CA mutations of either c.3140A>G (p.H1047R) or c.1633G>A (p.E545K). Aspirin induced greater dose-dependent loss of cell viability in PIK3CA -mutant cells than in PIK3CA -wild-type cells after treatment for 48 and 72 hours. Aspirin treatment also led to higher proportions of apoptotic cells and G0/G1 phase arrest in PIK3CA -mutant cells than in PIK3CA -wild-type cells. Aspirin treatment of isogenic SW48 cells carrying a PIK3CA mutation, either c.3140A>G (p.H1047R) or c.1633G>A (p. E545K), resulted in a more significant loss of cell viability compared to wild-type controls. Our findings indicate that aspirin causes cell cycle arrest, induces apoptosis, and leads to loss of cell viability more profoundly in PIK3CA -mutated colon cancer cells than in PIK3CA -wild-type colon cancer cells. These findings support the use of aspirin to treat patients with PIK3CA -mutant colon cancer.

Effect of carbonation temperature on CO_2 adsorption capacity of CaO derived from micro/nanostructured aragonite CaCO_3

International Nuclear Information System (INIS)

Hlaing, Nwe Ni; Sreekantan, Srimala; Hinode, Hirofumi; Kurniawan, Winarto; Thant, Aye Aye; Othman, Radzali; Mohamed, Abdul Rahman; Salime, Chris

2016-01-01

Recent years, CaO-based synthetic materials have been attracted attention as potential adsorbents for CO_2 capture mainly due to their high CO_2 adsorption capacity. In this study, micro/nanostructured aragonite CaCO_3 was synthesized by a simple hydrothermal method with using polyacrylamide (PAM). The structural, morphological and thermal properties of the synthesized sample were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and thermogravimetry analysis (TG-DTA). The XRD and FESEM results showed that the obtained sample was aragonite CaCO_3 with aggregated nanorods and microspheres composed of nanorods. A TG-DTA apparatus with Thermoplus 2 software was used to investigate the effect of carbonation temperature on the CO_2 adsorption capacity of CaO derived from aragonite CaCO_3 sample. At 300 °C, the sample reached the CO_2 adsorption capacity of 0.098 g-CO_2/g-adsorbent, whereas the sample achieved the highest capacity of 0.682 g-CO_2/g-adsorbent at 700 °C. The results showed that the carbonation temperature significantly influenced on the CO_2 adsorption capacity of the CaO derived from aragonite CaCO_3.

Dopamine D1/D5, but not D2/D3, receptor dependency of synaptic plasticity at hippocampal mossy fiber synapses that is enabled by patterned afferent stimulation, or spatial learning

Directory of Open Access Journals (Sweden)

Hardy Hagena

2016-09-01

Full Text Available Although the mossy fiber (MF synapses of the hippocampal CA3 region display quite distinct properties in terms of the molecular mechanisms that underlie synaptic plasticity, they nonetheless exhibit persistent (>24h synaptic plasticity that is akin to that observed at the Schaffer collateral (SCH-CA1 and perforant path (PP-dentate gyrus (DG synapses of freely behaving rats. In addition, they also respond to novel spatial learning with very enduring forms of long-term potentiation (LTP and long-term depression (LTD. These latter forms of synaptic plasticity are directly related to the learning behavior: novel exploration of generalized changes in space facilitates the expression of LTP at MF-CA3 synapses, whereas exploration of novel configurations of large environmental features facilitates the expression of LTD. In the absence of spatial novelty, synaptic plasticity is not expressed. Motivation is a potent determinant of whether learning about spatial experience effectively occurs and the neuromodulator dopamine plays a key role in motivation-based learning. Prior research on the regulation by dopamine receptors of long-term synaptic plasticity in CA1 and dentate gyrus synapses in vivo suggests that whereas D2/D3 receptors may modulate a general predisposition toward expressing plasticity, D1/D5 receptors may directly regulate the direction of change in synaptic strength that occurs during learning. Although the CA3 region is believed to play a pivotal role in many forms of learning, the role of these receptors in persistent (>24h forms of synaptic plasticity at MF-CA3 synapses is unknown. Here, we report that whereas pharmacological antagonism of D2/D3 receptors had no impact on LTP or LTD, antagonism of D1/D5 receptors significantly impaired LTP and LTD that were induced by solely by means of patterned afferent stimulation, or LTP/LTD that are typically enhanced by the conjunction of afferent stimulation and novel spatial learning. These data

Menstrual Cycle Dependent Variability for Serum Tumor Markers CEA, AFP, CA 19-9, CA 125 and CA 15-3 in Healthy Women

Directory of Open Access Journals (Sweden)

Ayşe Binnur Erbağci

1999-01-01

Full Text Available Information on menstrual cycle dependent variation of tumor markers in healthy women is a subject of diagnostic efficiency and has an impact in elucidating the normal function of these markers. In this study midfollicular and midluteal concentrations of serum CEA, AFP, CA 19-9, CA 125, CA 15-3 and their relations with LH, FSH, prolactin, estradiol and progesterone were evaluated during ovulatory cycles in a group of 23 healthy female individuals. Samples were collected on the 7th and 21st day of the same menstrual cycle. Tumor marker and hormone concentrations were determined with chemiluminescence or electrochemiluminescence EIA methods. A significant phase-dependent difference was observed for CA 15-3, midluteal concentrations (mean ± SEM; 26.33 ± 1.56 U/ml higher than the midfollicular (mean ± SEM; 19.27 ± 1.49 U/ml concentrations (p < 0.001. But an obvious difference for other tumor markers investigated did not exist. Significant correlations of follicular and luteal CA 125 levels with body mass index of the subjects were observed (r:0.52, p < 0.05 and r:0.57, p < 0.005, respectively.

Lysosomes shape Ins(1,4,5)P3-evoked Ca2+ signals by selectively sequestering Ca2+ released from the endoplasmic reticulum

Science.gov (United States)

López-Sanjurjo, Cristina I.; Tovey, Stephen C.; Prole, David L.; Taylor, Colin W.

2013-01-01

Summary Most intracellular Ca2+ signals result from opening of Ca2+ channels in the plasma membrane or endoplasmic reticulum (ER), and they are reversed by active transport across these membranes or by shuttling Ca2+ into mitochondria. Ca2+ channels in lysosomes contribute to endo-lysosomal trafficking and Ca2+ signalling, but the role of lysosomal Ca2+ uptake in Ca2+ signalling is unexplored. Inhibition of lysosomal Ca2+ uptake by dissipating the H+ gradient (using bafilomycin A1), perforating lysosomal membranes (using glycyl-L-phenylalanine 2-naphthylamide) or lysosome fusion (using vacuolin) increased the Ca2+ signals evoked by receptors that stimulate inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] formation. Bafilomycin A1 amplified the Ca2+ signals evoked by photolysis of caged Ins(1,4,5)P3 or by inhibition of ER Ca2+ pumps, and it slowed recovery from them. Ca2+ signals evoked by store-operated Ca2+ entry were unaffected by bafilomycin A1. Video-imaging with total internal reflection fluorescence microscopy revealed that lysosomes were motile and remained intimately associated with the ER. Close association of lysosomes with the ER allows them selectively to accumulate Ca2+ released by Ins(1,4,5)P3 receptors. PMID:23097044

The center-to-limb behavior of CaI lambda 6573 and [Ca II] lambda 7324

International Nuclear Information System (INIS)

Ayres, T.R.; Testerman, L.

1978-01-01

Center-to-limb measurements of the Ca I lambda 6573 intercombination line and the Ca II lambda 7324 forbidden line are compared with synthetic profiles based on a simple representation of the non-LTE Ca-Ca + ionization equilibrium. The effects of photoionization from low lying excited states of neutral calcium are found to reduce the sensitivity of the lambda 6573 center-to-limb behavior as a thermal structure diagnostic. The synthetic center-to-limb behavior is also sensitive to uncertainties in the nonthermal broadening. Nevertheless, the measured center-to-limb behavior of lambda 6573 favors a 'cool' photospheric model similar to the Vernazza, Avrett, and Loeser model M over hotter models based on the Ca II K wings. The non-LTE calcium abundance obtained from the disk center equivalent widths of lambda 6573 and lambda 7324 using the best fit model is Asub(Ca)approximately=2.1+-0.2x10 -6 (by number relative to hydrogen). Applications of these lines as diagnostics of the Ca-Ca + ionization equilibrium in other stars are briefly discussed. (Auth.)

Sustained increase of spontaneous input and spike transfer in the CA3-CA1 pathway following long term potentiation in vivo

Directory of Open Access Journals (Sweden)

Oscar eHerreras

2012-10-01

Full Text Available Long term potentiation (LTP is commonly used to study synaptic plasticity but the associated changes in the spontaneous activity of individual neurons or the computational properties of neural networks in vivo remain largely unclear. The multisynaptic origin of spontaneous spikes makes difficult estimating the impact of a particular potentiated input. Accordingly, we adopted an approach that isolates pathway-specific postsynaptic activity from raw local field potentials (LFPs in the rat hippocampus in order to study the effects of LTP on ongoing spike transfer between cell pairs in the CA3-CA1 pathway. CA1 Schaffer-specific LFPs elicited by spontaneous clustered firing of CA3 pyramidal cells involved a regular succession of elementary micro-field-EPSPs (gamma-frequency that fired spikes in CA1 units. LTP increased the amplitude but not the frequency of these ongoing excitatory quanta. Also, the proportion of Schaffer-driven spikes in both CA1 pyramidal cells and interneurons increased in a cell-specific manner only in previously connected CA3-CA1 cell pairs, i.e., when the CA3 pyramidal cell had shown pre-LTP significant correlation with firing of a CA1 unit and potentiated spike-triggered average of Schaffer LFPs following LTP. Moreover, LTP produced subtle reorganization of presynaptic CA3 cell assemblies. These findings show effective enhancement of pathway specific ongoing activity which leads to increased spike transfer in potentiated segments of a network. These indicate that plastic phenomena induced by external protocols may intensify spontaneous information flow across specific channels as proposed in transsynaptic propagation of plasticity and synfire chain hypotheses that may be the substrate for different types of memory involving multiple brain structures.

Analysis of Spatial Concepts, Spatial Skills and Spatial Representations in New York State Regents Earth Science Examinations

Science.gov (United States)

Kastens, Kim A.; Pistolesi, Linda; Passow, Michael J.

2014-01-01

Research has shown that spatial thinking is important in science in general, and in Earth Science in particular, and that performance on spatially demanding tasks can be fostered through instruction. Because spatial thinking is rarely taught explicitly in the U.S. education system, improving spatial thinking may be "low-hanging fruit" as…

Pharmacological Intervention of Hippocampal CA3 NMDA Receptors Impairs Acquisition and Long-Term Memory Retrieval of Spatial Pattern Completion Task

Science.gov (United States)

Fellini, Laetitia; Florian, Cedrick; Courtey, Julie; Roullet, Pascal

2009-01-01

Pattern completion is the ability to retrieve complete information on the basis of incomplete retrieval cues. Although it has been demonstrated that this cognitive capacity depends on the NMDA receptors (NMDA-Rs) of the hippocampal CA3 region, the role played by these glutamatergic receptors in the pattern completion process has not yet been…

PIK3CA Mutation in Colorectal Cancer: Relationship with Genetic and Epigenetic Alterations

Directory of Open Access Journals (Sweden)

Katsuhiko Nosho

2008-06-01

Full Text Available Somatic PIK3CA mutations are often present in colorectal cancer. Mutant PIK3CA activates AKT signaling, which up-regulates fatty acid synthase (FASN. Microsatellite instability (MSI and CpG island methylator phenotype (CIMP are important molecular classifiers in colorectal cancer. However, the relationship between PIK3CA mutation, MSI and CIMP remains uncertain. Using Pyrosequencing technology, we detected PIK3CA mutations in 91 (15% of 590 population-based colorectal cancers. To determine CIMP status, we quantified DNA methylation in eight CIMP-specific promoters [CACNA1G, CDKN2A (p16, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1] by real-time polymerase chain reaction (MethyLight. PIK3CA mutation was significantly associated with mucinous tumors [P = .0002; odds ratio (OR = 2.44], KRAS mutation (P < .0001; OR = 2.68, CIMP-high (P = .03; OR = 2.08, phospho–ribosomal protein S6 expression (P = .002; OR = 2.19, and FASN expression (P = .02; OR = 1.85 and inversely with p53 expression (P = .01; OR = 0.54 and β-catenin (CTNNB1 alteration (P = .004; OR = 0.43. In addition, PIK3CA G-to-A mutations were associated with MGMT loss (P = .001; OR = 3.24 but not with MGMT promoter methylation. In conclusion, PIK3CA mutation is significantly associated with other key molecular events in colorectal cancer, and MGMT loss likely contributes to the development of PIK3CA G>A mutation. In addition, Pyrosequencing is useful in detecting PIK3CA mutation in archival paraffin tumor tissue. PIK3CA mutational data further emphasize heterogeneity of colorectal cancer at the molecular level.

Thermoelectric properties of Ca1-xYxMnO3 and Ca0.9Y0.1-yFeyMnO3 perovskite compounds

DEFF Research Database (Denmark)

Thuy, Nguyen Thi; Minh, Dang Le; Van Nong, Ngo

2012-01-01

Polycrystalline Ca1-xYxMnO3 (x = 0.0; 0.1; 0.3; 0.5; 0.7) and Ca0.9Y0.1-yFeyMnO3 (y = 0.00; 0.01; 0.03; 0.05) compounds were prepared by solid-state reaction. X-ray diffraction (XRD) analysis revealed all XRD peaks of all the samples as identical to the orthorhombic structure. The thermoelectric ...

Magnetic Field Effects on CaCO3 Precipitation Process in Hard Water

Directory of Open Access Journals (Sweden)

Nelson Saksono

2010-10-01

Full Text Available Magnetic treatment is applied as physical water treatment for scale prevention especially CaCO3, from hard water in piping equipment by reducing its hardness.Na2CO3 and CaCl2 solution sample was used in to investigate the magnetic fields influence on the formation of particle of CaCO3. By changing the strength of magnetic fields, exposure time and concentration of samples solution, this study presents quantitative results of total scale deposit, total precipitated CaCO3 and morphology of the deposit. This research was run by comparing magnetically and non-magnetically treated  samples. The results showed an increase of deposits formation rate and total number of precipitated CaCO3 of magnetically treated samples. The increase of concentration solution sample will also raised the deposit under magnetic  field. Microscope images showed a greater number but smaller size of CaCO3 deposits form in magnetically treated samples, and aggregation during the processes. X-ray diffraction (XRD analysis showed that magnetically samples were dominated by calcite. But, there was a significant decrease of calcite’s peak intensities from magnetized  samples that indicated the decrease of the amount of calcite and an increase of total amorphous of deposits. This result  showed that magnetization of hard water leaded to the decreasing of ion Ca2+ due to the increasing of total CaCO3 precipitation process.

Tunable Yellow-Red Photoluminescence and Persistent Afterglow in Phosphors Ca4LaO(BO3)3:Eu3+ and Ca4EuO(BO3)3.

Science.gov (United States)

Chen, Zhen; Pan, Yuexiao; Xi, Luqing; Pang, Ran; Huang, Shaoming; Liu, Guokui

2016-11-07

In most Eu 3+ activated phosphors, only red luminescence from the 5 D 0 is obtainable, and efficiency is limited by concentration quenching. Herein we report a new phosphor of Ca 4 LaO(BO 3 ) 3 :Eu 3+ (CLBO:Eu) with advanced photoluminescence properties. The yellow luminescence emitted from the 5 D 1,2 states is not thermally quenched at room temperature. The relative intensities of the yellow and red emission bands depend strongly on the Eu 3+ doping concentration. More importantly, concentration quenching of Eu 3+ photoluminescence is absent in this phosphor, and the stoichiometric compound of Ca 4 EuO(BO 3 ) 3 emits stronger luminescence than the Eu 3+ doped compounds of CLBO:Eu; it is three times stronger than that of a commercial red phosphor of Y 2 O 3 :Eu 3+ . Another beneficial phenomenon is that ligand-to-metal charge transfer (CT) transitions occur in the long UV region with the lowest charge transfer band (CTB) stretched down to about 3.67 eV (∼330 nm). The CT transitions significantly enhance Eu 3+ excitation, and thus result in stronger photoluminescence and promote trapping of excitons for persistent afterglow emission. Along with structure characterization, optical spectra and luminescence dynamics measured under various conditions as a function of Eu 3+ doping, temperature, and excitation wavelength are analyzed for a fundamental understanding of electronic interactions and for potential applications.

How the cerebellum may monitor sensory information for spatial representation

Science.gov (United States)

Rondi-Reig, Laure; Paradis, Anne-Lise; Lefort, Julie M.; Babayan, Benedicte M.; Tobin, Christine

2014-01-01

The cerebellum has already been shown to participate in the navigation function. We propose here that this structure is involved in maintaining a sense of direction and location during self-motion by monitoring sensory information and interacting with navigation circuits to update the mental representation of space. To better understand the processing performed by the cerebellum in the navigation function, we have reviewed: the anatomical pathways that convey self-motion information to the cerebellum; the computational algorithm(s) thought to be performed by the cerebellum from these multi-source inputs; the cerebellar outputs directed toward navigation circuits and the influence of self-motion information on space-modulated cells receiving cerebellar outputs. This review highlights that the cerebellum is adequately wired to combine the diversity of sensory signals to be monitored during self-motion and fuel the navigation circuits. The direct anatomical projections of the cerebellum toward the head-direction cell system and the parietal cortex make those structures possible relays of the cerebellum influence on the hippocampal spatial map. We describe computational models of the cerebellar function showing that the cerebellum can filter out the components of the sensory signals that are predictable, and provides a novelty output. We finally speculate that this novelty output is taken into account by the navigation structures, which implement an update over time of position and stabilize perception during navigation. PMID:25408638

Compound Method to Disperse CaCO3 Nanoparticles to Nano-Size in Water.

Science.gov (United States)

Gu, Sui; Cai, Jihua; Wang, Jijun; Yuan, Ye; Chang, Dewu; Chikhotkin, Viktor F

2015-12-01

The invalidation of CaCO3 nanoparticles (nCaCO3) is often caused by the fact of agglomeration and inhomogeneous dispersion which limits its application into water-based drilling muds for low permeability reservoirs such as coalbed methane reservoir and shale gas/oil reservoir. Effective methods to disperse nCaCO3 to nano-size (≤ 100 nm) in water have seldom been reported. Here we developed a compound method containing mechanical stirring, ultrasonic treatment, the use of surfactant and stabilizer to disperse nCaCO3 in water. It comprises the steps adding 2% nCaCO3, 1% sodium dodecyl sulfonate (SDS), 2% cetyltrimethyl ammonium bromide (CTAB), 2% OP-10, 3% to 4% biopolymer (XC) in water successively, stirring it at a shear rate of 6000 to 8000 r/min for 15 minutes and treating it with ultrasonic at a frequency of 28 KHz for 30 to 40 minutes. The dispersed nCaCO3 was characterized with scanning electron microscope (SEM), transmission electron microscope (TEM) and particle size distribution (PSD) tests. We found that nCaCO3 could be dispersed to below 100 nm in water and the medium value of nCaCO3 was below 50 nm. This method paved the way for the utilization of nCaCO3 in drilling fluid and completion fluid for low permeability reservoirs such as coal seams and shale gas/oil formations.

Effects of 45Ca on murine skeletal muscle. 3

International Nuclear Information System (INIS)

Malhotra, R.K.; Asotra, K.; Katoch, S.S.; Krishan, K.

1983-01-01

Swiss albino mice were injected intraperitoneally with 3.7x10 4 Bq and 7.4x10 4 Bq 45 Ca/g body weight. Mice of both dose groups were autopsied on days 1, 3, 5, 7, 14 and 28 and activities of alanine aminotransferase and aspartate aminotransferase bioassayed in diaphragm and gastrocnemius in 45 Ca-treated and normal mice. Alanine aminotransferase activity in the two muscles increased in response to 45 Ca administration suggesting a stepped up utilization of alanine in glucose generation. Aspartate aminotransferase levels, on the other hand, diminished in both the 45 Ca-treated muscles and are maintained at low values throughout the 28 day period of study. The results suggest an innate ability of skeletal muscle to selectively utilize either of the two glucogenic amino acids during radiation stress. The data are discussed in light of previous findings on glycogen accumulation in irradiated skeletal muscle. (author)

The Ca(PO3)2-Sr(PO3)2 system

International Nuclear Information System (INIS)

Bukhalova, G.A.; Tokman, I.A.

1977-01-01

Phase diagram of the system Ca(PO 3 ) 2 -Sr(PO 3 ) 2 has been studied and plotted with the aid of differential thermal, visual polythermal, X-ray analysis, and infrared spectroscopy. Continuous solid solutions are formed in the system with a minimum at 968 deg C and 25 mol.% of Sr(PO 3 ) 2 . Solid solutions decompose with the formation of about 30 mol.% of Sr(PO 3 ) 2

Bone scan and serum CA 15-3 in bone metastasis in breast cancer

International Nuclear Information System (INIS)

Mendoza, G.; Cano, R.; Morales, R.; Guzman, C.

1996-01-01

CA 15-3 is a tumor marker useful in evolution control of breast cancer, being the serum levels trend the most important parameter. The purpose of this study was to report our experience and show the concordance of bone scan and CA 15-3 in patients with breast cancer attending the Breast and Bone Department of INEN from June to December 1993. One hundred patients had serum CA 15-3 quantification between June and December of 1993 in Nuclear Medicine Center (Peruvian Institute of Nuclear Energy and National Institute of Neoplasic Diseases). We selected 52 patients which simultaneously had a bone scan performed. Patients age ranged from 21 to 67 years (media of 44,57 years). 99m Tc methylenediphosphonate produced by IPEN was the radiopharmaceutical employed. A GE AZS-400 gamma camera was utilized to obtain the bone scans. Ca 15-5 quantification was performed with ELSA-CA 15-3 (CIS bio France) IRMA kit. Bone scan and CA 15-3 media of 17,06 U/ml (DS 15,4). Eight patients had a positive bone scan with a CA 15-3 media of 41,6 U/ml (SD 23,0). CA 15-3 levels ranged between 4,6 and 96,0 U/ml in the first group and 10,1 U/ml to 75,0 U/ml in the second group. Using a cut-off point of 30 U/ml the sensitivity of CA 15-3 was 62,5% and the specificity 93,2% respectively. Mean CA 15-3 values of the negative and positive bone scan groups were significantly different (p=0,0361). The high negative predictive value of CA 15-3 may help to establish which patients will benefit from bone scan procedure. (authors) 42 refs., 2 tabs

The essence of student visual-spatial literacy and higher order thinking skills in undergraduate biology.

Science.gov (United States)

Milner-Bolotin, Marina; Nashon, Samson Madera

2012-02-01

Science, engineering and mathematics-related disciplines have relied heavily on a researcher's ability to visualize phenomena under study and being able to link and superimpose various abstract and concrete representations including visual, spatial, and temporal. The spatial representations are especially important in all branches of biology (in developmental biology time becomes an important dimension), where 3D and often 4D representations are crucial for understanding the phenomena. By the time biology students get to undergraduate education, they are supposed to have acquired visual-spatial thinking skills, yet it has been documented that very few undergraduates and a small percentage of graduate students have had a chance to develop these skills to a sufficient degree. The current paper discusses the literature that highlights the essence of visual-spatial thinking and the development of visual-spatial literacy, considers the application of the visual-spatial thinking to biology education, and proposes how modern technology can help to promote visual-spatial literacy and higher order thinking among undergraduate students of biology.

The sup(40,44,48)Ca(3He, 3He) and (3He, 4He) reactions at 50 MeV

International Nuclear Information System (INIS)

Griffiths, R.J.; Duggan, F.; Clarke, N.M.

1981-01-01

Measurements have been made of the ( 3 He, 3 He) and ( 3 He, 4 He) reactions on the isotopes of calcium 40 Ca, 44 Ca and 48 Ca at an energy of 50.4 MeV. The results have been analysed with conventional optical potentials and DWBA. The adequacy of the former and inadequacy of the latter for reactions with composite particles is discussed. (author)

Bi4Sr3Ca3Cu4O16 galss and superconducting glass ceramics

International Nuclear Information System (INIS)

Zheng, H.; Mackenzie, J.D.

1988-01-01

Bi 4 Sr 3 Ca 3 Cu 4 O 16 glass has been successfully fabricated by the melting process. Glass transition temperature, crystallization temperature, and liquid temperature of the glass are 434, 478, and 833 0 C, respectively. After the glass is heat treated at 800 0 C, a glass ceramic is formed. A comparison of the x-ray-diffraction pattern of the superconducting Bi 4 Sr 3 Ca 3 Cu 4 O/sub 16+//sub x/ ceramic to the Bi 4 Sr 3 Ca 3 Cu 4 O 16 glass ceramic revealed preferred orientation in the glass ceramic crystals. The superconducting transition temperatures T/sub c//sub (onset)/ and T/sub c//sub (zero)/ of the glass ceramics are 100 and 45 K, respectively

Trapping processes in CaS:Eu2+,Tm3+

International Nuclear Information System (INIS)

Jia, Dongdong; Jia, Weiyi; Evans, D. R.; Dennis, W. M.; Liu, Huimin; Zhu, Jing; Yen, W. M.

2000-01-01

CaS:Eu 2+ ,Tm 3+ is a persistent red phosphor. Thermoluminescence was measured under different excitation and thermal treatment conditions. The results reveal that the charge defects, created by substituting Tm 3+ for Ca 2+ , serve as hole traps for the afterglow at room temperature. Tm 3+ plays the role of deep electron trapping centers, capturing electrons either through the conduction band or directly from the excited Eu 2+ ions. These two processes, in which two different sites of Tm 3+ are involved, correspond to two traps with different depths. (c) 2000 American Institute of Physics

Acoustic Monitoring of Gravity-Driven Controls on CaCO3 Precipitates in a Fracture

Science.gov (United States)

Xu, Z.; Sheets, J.; Zhang, L.; Kim, D.; Kneafsey, T. J.; Cole, D. R.; Jun, Y. S.; Pyrak-Nolte, L. J.

2017-12-01

Sealing fractures by mineral precipitation is an important process for improving caprock integrity in subsurface reservoirs. In this study, the ability to monitor precipitate distribution in fractures with buoyant fluids was examined. Fractures with uniform aperture distributions of 0.5, 1.0 and 2.0 mm were created from acrylic plates to enable direct imaging of precipitate formation over time. CaCO3 precipitation was induced in a fracture from invasion of 1M CaCl2 and 0.3M Na2CO3 solutions. During chemical invasion, a fracture plane was oriented either parallel or perpendicular to gravity. Acoustic (P) wave transmission ( 1 MHz) and optical imaging were used to monitor the sample prior to, during and after fluid injection. Complementary X-ray computed tomography was performed throughout the experiments on vertical fractures and post injection for the horizontal fractures. Precipitate particle sizes during formation were determined using SAXS and WAXS. In both horizontal and vertical fractures, the density contrast between the two solutions affected the spatial distribution of precipitation. In vertical fractures, the denser CaCl2 solution almost completely displaced the NaCO3 solution, causing strong localization of precipitates. However, in the horizontal fractures, flow stratification occurred in the 2 mm aperture fractures, with the less dense Na2CO3 flowing over the CaCl2 solution, resulting in a more even distribution of precipitates cross the fracture plane. P-wave amplitudes increased up to 8% and the arrival time decreased with precipitate accumulation in the horizontal fracture. This is consistent with a three-layered approach as the seismic impedance inside the fracture increases. The initial contact between the two was observed as a decrease in the P-wave amplitude. As precipitates accumulated, the amplitude recovered and increased, with greater increases observed along the mixing flow path. Fractures in the subsurface may seal differently depending on

Long afterglow property of Er"3"+ doped Ca_2SnO_4 phosphor

International Nuclear Information System (INIS)

Zhang, Dongyun; Shi, Mingming; Sun, Yiwen; Guo, Yunyun; Chang, Chengkang

2016-01-01

A novel green emitting long afterglow phosphor, Er"3"+ -doped Ca_2SnO_4 (Ca_2SnO_4:Er"3"+), was prepared successfully via a traditional high temperature solid–state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction (XRD), photoluminescence spectroscope (PLS), afterglow decay curve (ADC) and thermal luminescence spectroscope (TLS). Three main emission peaks of PLS locate at 524, 550 and 668 nm, corresponding to CIE chromaticity coordinates of x = 0.326, y = 0.6592. An optimal doping concentration of Er"3"+ of 2% was determined. The Ca_2SnO_4:Er"3"+ phosphors showed a typical triple-exponential afterglow decay behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Ca_2SnO_4:2 mol% Er"3"+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the Ca_2SnO_4 host with rare-earth ions (Er"3"+). - Highlights: • A novel green emitting long afterglow phosphor, Ca_2SnO_4:Er"3"+, was prepared. • An optimal doping concentration of Er"3"+ of 2% was determined. • After the UV source was turned off, the Ca_2SnO_4:Er"3"+ showed a typical triple-exponential afterglow decay behavior. • CIE chromaticity coordinates results confirmed a green light emitting of the Ca_2SnO_4:Er"3"+. • The persistent afterglow of the Ca_2SnO_4:Er"3"+ was attributed to suitable electron or hole traps.

BAG3 regulates contractility and Ca(2+) homeostasis in adult mouse ventricular myocytes.

Science.gov (United States)

Feldman, Arthur M; Gordon, Jennifer; Wang, JuFang; Song, Jianliang; Zhang, Xue-Qian; Myers, Valerie D; Tilley, Douglas G; Gao, Erhe; Hoffman, Nicholas E; Tomar, Dhanendra; Madesh, Muniswamy; Rabinowitz, Joseph; Koch, Walter J; Su, Feifei; Khalili, Kamel; Cheung, Joseph Y

2016-03-01

Bcl2-associated athanogene 3 (BAG3) is a 575 amino acid anti-apoptotic protein that is constitutively expressed in the heart. BAG3 mutations, including mutations leading to loss of protein, are associated with familial cardiomyopathy. Furthermore, BAG3 levels have been found to be reduced in end-stage non-familial failing myocardium. In contrast to neonatal myocytes in which BAG3 is found in the cytoplasm and involved in protein quality control and apoptosis, in adult mouse left ventricular (LV) myocytes BAG3 co-localized with Na(+)-K(+)-ATPase and L-type Ca(2+) channels in the sarcolemma and t-tubules. BAG3 co-immunoprecipitated with β1-adrenergic receptor, L-type Ca(2+) channels and phospholemman. To simulate decreased BAG3 protein levels observed in human heart failure, we targeted BAG3 by shRNA (shBAG3) in adult LV myocytes. Reducing BAG3 by 55% resulted in reduced contraction and [Ca(2+)]i transient amplitudes in LV myocytes stimulated with isoproterenol. L-type Ca(2+) current (ICa) and sarcoplasmic reticulum (SR) Ca(2+) content but not Na(+)/Ca(2+) exchange current (INaCa) or SR Ca(2+) uptake were reduced in isoproterenol-treated shBAG3 myocytes. Forskolin or dibutyryl cAMP restored ICa amplitude in shBAG3 myocytes to that observed in WT myocytes, consistent with BAG3 having effects upstream and at the level of the receptor. Resting membrane potential and action potential amplitude were unaffected but APD50 and APD90 were prolonged in shBAG3 myocytes. Protein levels of Ca(2+) entry molecules and other important excitation-contraction proteins were unchanged in myocytes with lower BAG3. Our findings that BAG3 is localized at the sarcolemma and t-tubules while modulating myocyte contraction and action potential duration through specific interaction with the β1-adrenergic receptor and L-type Ca(2+) channel provide novel insight into the role of BAG3 in cardiomyopathies and increased arrhythmia risks in heart failure. Copyright © 2016 Elsevier Ltd. All rights

BAG3 regulates contractility and Ca2+ homeostasis in adult mouse ventricular myocytes

Science.gov (United States)

Feldman, Arthur M.; Gordon, Jennifer; Wang, JuFang; Song, Jianliang; Zhang, Xue-Qian; Myers, Valerie D.; Tilley, Douglas G.; Gao, Erhe; Hoffman, Nicholas E.; Tomar, Dhanendra; Madesh, Muniswamy; Rabinowitz, Joseph; Koch, Walter J.; Su, Feifei; Khalili, Kamel; Cheung, Joseph Y.

2016-01-01

Bcl2-associated athanogene 3 (BAG3) is a 575 amino acid anti-apoptotic protein that is constitutively expressed in the heart. BAG3 mutations, including mutations leading to loss of protein, are associated with familial cardiomyopathy. Furthermore, BAG3 levels have been found to be reduced in end-stage non-familial failing myocardium. In contrast to neonatal myocytes in which BAG3 is found in the cytoplasm and involved in protein quality control and apoptosis, in adult mouse left ventricular (LV) myocytes BAG3 co-localized with Na+-K+-ATPase and L-type Ca2+ channels in the sarcolemma and t-tubules. BAG3 co-immunoprecipitated with β1-adrenergic receptor, L-type Ca2+ channels and phospholemman. To simulate decreased BAG3 protein levels observed in human heart failure, we targeted BAG3 by shRNA (shBAG3) in adult LV myocytes. Reducing BAG3 by 55% resulted in reduced contraction and [Ca2+]i transient amplitudes in LV myocytes stimulated with isoproterenol. L-type Ca2+ current (ICa) and sarcoplasmic reticulum (SR) Ca2+ content but not Na+/Ca2+ exchange current (INaCa) or SR Ca2+ uptake were reduced in isoproterenol-treated shBAG3 myocytes. Forskolin or dibutyrl cAMP restored ICa amplitude in shBAG3 myocytes to that observed in WT myocytes, consistent with BAG3 having effects upstream and at the level of the receptor. Resting membrane potential and action potential amplitude were unaffected but APD50 and APD90 were prolonged in shBAG3 myocytes. Protein levels of Ca2+ entry molecules and other important excitation-contraction proteins were unchanged in myocytes with lower BAG3. Our findings that BAG3 is localized at the sarcolemma and t-tubules while modulating myocyte contraction and action potential duration through specific interaction with the β1-adrenergic receptor and L-type Ca2+ channel provide novel insight into the role of BAG3 in cardiomyopathies and increased arrhythmia risks in heart failure. PMID:26796036

Investigation of Spatial Variation of Sea States Offshore of Humboldt Bay CA Using a Hindcast Model.

Energy Technology Data Exchange (ETDEWEB)

Dallman, Ann Renee; Neary, Vincent Sinclair

2014-10-01

Spatial variability of sea states is an important consideration when performing wave resource assessments and wave resource characterization studies for wave energy converter (WEC) test sites and commercial WEC deployments. This report examines the spatial variation of sea states offshore of Humboldt Bay, CA, using the wave model SWAN . The effect of depth and shoaling on bulk wave parameters is well resolved using the model SWAN with a 200 m grid. At this site, the degree of spatial variation of these bulk wave parameters, with shoaling generally perpendicular to the depth contours, is found to depend on the season. The variation in wave height , for example, was higher in the summer due to the wind and wave sheltering from the protruding land on the coastline north of the model domain. Ho wever, the spatial variation within an area of a potential Tier 1 WEC test site at 45 m depth and 1 square nautical mile is almost negligible; at most about 0.1 m in both winter and summer. The six wave characterization parameters recommended by the IEC 6 2600 - 101 TS were compared at several points along a line perpendicular to shore from the WEC test site . As expected, these parameters varied based on depth , but showed very similar seasonal trends.

CA 15-3: uses and limitation as a biomarker for breast cancer.

LENUS (Irish Health Repository)

Duffy, Michael J

2012-02-01

CA 15-3 which detects soluble forms of MUC-1 protein is the most widely used serum marker in patients with breast cancer. Its main use is for monitoring therapy in patients with metastatic disease. In monitoring therapy in this setting, CA 15-3 should not be used alone but measured in conjunction with diagnostic imaging, clinical history and physical examination. CA 15-3 is particularly valuable for treatment monitoring in patients that have disease that cannot be evaluated using existing radiological procedures. CA 15-3 may also be used in the postoperative surveillance of asymptomatic women who have undergone surgery for invasive breast cancer. In this setting, serial determination can provide median lead-times of 5-6 months in the early detection of recurrent\\/metastatic breast cancer. It is unclear however, whether administering systemic therapy based on this lead-time improves patient outcome. Consequently, expert panels disagree on the utility of regularly measuring CA 15-3 in the postoperative surveillance of asymptomatic women following a diagnosis of breast cancer. The main limitation of CA 15-3 as a marker for breast cancer is that serum levels are rarely increased in patients with early or localized disease.

Rosiglitazone attenuates inflammation and CA3 neuronal loss following traumatic brain injury in rats

International Nuclear Information System (INIS)

Liu, Hao; Rose, Marie E.; Culver, Sherman; Ma, Xiecheng; Dixon, C. Edward; Graham, Steven H.

2016-01-01

Rosiglitazone, a potent peroxisome proliferator-activated receptor (PPAR)-γ agonist, has been shown to confer neuroprotective effects in stroke and spinal cord injury, but its role in the traumatic brain injury (TBI) is still controversial. Using a controlled cortical impact model in rats, the current study was designed to determine the effects of rosiglitazone treatment (6 mg/kg at 5 min, 6 h and 24 h post injury) upon inflammation and histological outcome at 21 d after TBI. In addition, the effects of rosiglitazone upon inflammatory cytokine transcription, vestibulomotor behavior and spatial memory function were determined at earlier time points (24 h, 1–5 d, 14–20 d post injury, respectively). Compared with the vehicle-treated group, rosiglitazone treatment suppressed production of TNFα at 24 h after TBI, attenuated activation of microglia/macrophages and increased survival of CA3 neurons but had no effect on lesion volume at 21 d after TBI. Rosiglitazone-treated animals had improved performance on beam balance testing, but there was no difference in spatial memory function as determined by Morris water maze. In summary, this study indicates that rosiglitazone treatment in the first 24 h after TBI has limited anti-inflammatory and neuroprotective effects in rat traumatic injury. Further study using an alternative dosage paradigm and more sensitive behavioral testing may be warranted. - Highlights: • Effects of rosiglitazone after CCI were evaluated using a rat TBI model. • Rosiglitazone suppressed production of TNFα at 24 h after CCI. • Rosiglitazone inhibited microglial activation at 21 d after CCI. • Rosiglitazone increased survival of CA3 neurons at 21 d after CCI. • Rosiglitazone-treated animals had improved performance in beam balance testing.

Rosiglitazone attenuates inflammation and CA3 neuronal loss following traumatic brain injury in rats

Energy Technology Data Exchange (ETDEWEB)

Liu, Hao; Rose, Marie E. [Geriatric Research Educational and Clinical Center, V.A. Pittsburgh Healthcare System, PA (United States); Department of Neurology, University of Pittsburgh School of Medicine, PA (United States); Culver, Sherman; Ma, Xiecheng; Dixon, C. Edward [Geriatric Research Educational and Clinical Center, V.A. Pittsburgh Healthcare System, PA (United States); Department of Neurosurgery, University of Pittsburgh, PA 15216 (United States); Department of Critical Care Medicine, University of Pittsburgh, PA 15216 (United States); Graham, Steven H., E-mail: Steven.Graham@va.gov [Geriatric Research Educational and Clinical Center, V.A. Pittsburgh Healthcare System, PA (United States); Department of Neurology, University of Pittsburgh School of Medicine, PA (United States)

2016-04-15

Rosiglitazone, a potent peroxisome proliferator-activated receptor (PPAR)-γ agonist, has been shown to confer neuroprotective effects in stroke and spinal cord injury, but its role in the traumatic brain injury (TBI) is still controversial. Using a controlled cortical impact model in rats, the current study was designed to determine the effects of rosiglitazone treatment (6 mg/kg at 5 min, 6 h and 24 h post injury) upon inflammation and histological outcome at 21 d after TBI. In addition, the effects of rosiglitazone upon inflammatory cytokine transcription, vestibulomotor behavior and spatial memory function were determined at earlier time points (24 h, 1–5 d, 14–20 d post injury, respectively). Compared with the vehicle-treated group, rosiglitazone treatment suppressed production of TNFα at 24 h after TBI, attenuated activation of microglia/macrophages and increased survival of CA3 neurons but had no effect on lesion volume at 21 d after TBI. Rosiglitazone-treated animals had improved performance on beam balance testing, but there was no difference in spatial memory function as determined by Morris water maze. In summary, this study indicates that rosiglitazone treatment in the first 24 h after TBI has limited anti-inflammatory and neuroprotective effects in rat traumatic injury. Further study using an alternative dosage paradigm and more sensitive behavioral testing may be warranted. - Highlights: • Effects of rosiglitazone after CCI were evaluated using a rat TBI model. • Rosiglitazone suppressed production of TNFα at 24 h after CCI. • Rosiglitazone inhibited microglial activation at 21 d after CCI. • Rosiglitazone increased survival of CA3 neurons at 21 d after CCI. • Rosiglitazone-treated animals had improved performance in beam balance testing.

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia

Directory of Open Access Journals (Sweden)

Rossner Moritz

2007-10-01

Full Text Available Abstract Background The different physiological repertoire of CA3 and CA1 neurons in the hippocampus, as well as their differing behaviour after noxious stimuli are ultimately based upon differences in the expressed genome. We have compared CA3 and CA1 gene expression in the uninjured brain, and after cerebral ischemia using laser microdissection (LMD, RNA amplification, and array hybridization. Results Profiling in CA1 vs. CA3 under normoxic conditions detected more than 1000 differentially expressed genes that belong to different, physiologically relevant gene ontology groups in both cell types. The comparison of each region under normoxic and ischemic conditions revealed more than 5000 ischemia-regulated genes for each individual cell type. Surprisingly, there was a high co-regulation in both regions. In the ischemic state, only about 100 genes were found to be differentially expressed in CA3 and CA1. The majority of these genes were also different in the native state. A minority of interesting genes (e.g. inhibinbetaA displayed divergent expression preference under native and ischemic conditions with partially opposing directions of regulation in both cell types. Conclusion The differences found in two morphologically very similar cell types situated next to each other in the CNS are large providing a rational basis for physiological differences. Unexpectedly, the genomic response to ischemia is highly similar in these two neuron types, leading to a substantial attenuation of functional genomic differences in these two cell types. Also, the majority of changes that exist in the ischemic state are not generated de novo by the ischemic stimulus, but are preexistant from the genomic repertoire in the native situation. This unexpected influence of a strong noxious stimulus on cell-specific gene expression differences can be explained by the activation of a cell-type independent conserved gene-expression program. Our data generate both novel

Synthesis and characterization of Er3+ doped CaF2 nanoparticles

International Nuclear Information System (INIS)

Zhi Guanglin; Song Jinghong; Mei Bingchu; Zhou Weibing

2011-01-01

Highlights: → Er 3+ :CaF 2 nanoparticles were synthesized by co-precipitation method with particle size of 8-36 nm. → Increasing dopant concentration increases lattice constants and decreases grain size. → Annealing treatment has a remarkable effect on luminescence properties. → Luminescence intensity decrease with the increasing of the dopant concentration. - Abstract: Er 3+ doped CaF 2 nanoparticles were synthesized by a chemical co-precipitation method. Effect of the dopant concentrations on the structure and optical properties of the CaF 2 nanoparticles was investigated. The X-ray powder diffraction and transmission electron microscopy analysis was used to characterize the structure and morphology of the nanoparticles. The nanoparticles with different dopant concentration exhibited a sphere-like morphology with diameters of about 8-36 nm. The incorporation of Er 3+ ions into CaF 2 resulted in the decrease in grain size and deterioration of crystallinity, but enlarged the lattice constants of CaF 2 . Additional annealing treatment at 400 deg. C to the prepared CaF 2 removed the NO 3 - and OH - groups adsorbed on the particles' surfaces, and improved the optical properties of the nanoparticles. The fluorescence intensity, with a maximum at approximately 0.4 mol%, decreased with the increase in doping concentration because of concentration quenching.

Characterization of Corn Starch Films Reinforced with CaCO3 Nanoparticles

Science.gov (United States)

Sun, Qingjie; Xi, Tingting; Li, Ying; Xiong, Liu

2014-01-01

The characterization of corn starch (CS) films impregnated with CaCO3 nanoparticles was investigated. Criteria such as morphology, crystallinity, water vapor permeability (WVP), opacity, and mechanical properties were the focus of the investigation. It was found that the CaCO3 contents had significant effects on the tensile properties of the nanocomposite films. The addition of CaCO3 nanoparticles to the CS films significantly increased tensile strength from 1.40 to 2.24 MPa, elongation from 79.21 to 118.98%, and Young’s modulus from 1.82 to 2.41 MPa. The incorporation of CaCO3 nanoparticles increased the opacity of films, lowered the degree of WVP and film solubility value compared to those of the CS films. The results of scanning electron microscopy (SEM) showed that with the increase of CaCO3 nanoparticles content in starch films, the roughness of the films increased, and pores or cavities were found on the surface of the films, while small cracks were observed in the structures of the fractured surfaces. X-ray diffraction showed that the addition of nanoparticles increased the peaks in the intensity of films. PMID:25188503

New High Pressure Phase of CaCO3: Implication for the Deep Diamond Formation

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Mao, Z.; Li, X.; Zhang, Z.; Lin, J. F.; Ni, H.; Prakapenka, V.

2017-12-01

Surface carbon can be transported to the Earth's deep interior through sinking subduction slabs. Carbonates, including CaCO3, MgCO3 and MgCa(CO3)2, are important carbon carriers for the deep carbon cycle. Experimental studies on the phase stability of carbonates with coexisting mantle minerals at relevant pressure and temperature conditions are thus important for understanding the deep carbon cycle. In particular, recent petrological studies have revealed the evidence for the transportation of CaCO3 to the depth at least of the top lower mantle by analyzing the diamond inclusions. Yet the phase stability of CaCO3 at relevant pressure and temperature conditions of the top lower mantle is still unclear. Previous single-crystal study has shown that CaCO3 transforms from the CaCO3-III structure to CaCO3-VI at 15 GPa and 300 K. The CaCO3-VI is stable at least up to 40 GPa at 300 K. At high temperatures, CaCO3 in the aragonite structure will directly transform into the post-aragonite structure at 40 GPa. However, a recent theoretical study predicted a new phase of CaCO3 with a space group of P21/c between 32 and 48 GPa which is different from previous experimental results. In this study, we have investigated the phase stability of CaCO3 at high pressure-temperature conditions using synchrotron X-ray diffraction in laser-heated diamond anvil cells. We report the discovery of a new phase of CaCO3 at relevant pressure-temperature conditions of the top lower mantle which is consistent with previous theoretical predictions. This new phase is an important carrier for the transportation of carbon to the Earth's lower mantle and crucial for growing deep diamonds in the region.

Representational Thickness

DEFF Research Database (Denmark)

Mullins, Michael

Contemporary communicational and informational processes contribute to the shaping of our physical environment by having a powerful influence on the process of design. Applications of virtual reality (VR) are transforming the way architecture is conceived and produced by introducing dynamic...... elements into the process of design. Through its immersive properties, virtual reality allows access to a spatial experience of a computer model very different to both screen based simulations as well as traditional forms of architectural representation. The dissertation focuses on processes of the current...... representation? How is virtual reality used in public participation and how do virtual environments affect participatory decision making? How does VR thus affect the physical world of built environment? Given the practical collaborative possibilities of immersive technology, how can they best be implemented...

The 3-D global spatial data model foundation of the spatial data infrastructure

CERN Document Server

Burkholder, Earl F

2008-01-01

Traditional methods for handling spatial data are encumbered by the assumption of separate origins for horizontal and vertical measurements. Modern measurement systems operate in a 3-D spatial environment. The 3-D Global Spatial Data Model: Foundation of the Spatial Data Infrastructure offers a new model for handling digital spatial data, the global spatial data model or GSDM. The GSDM preserves the integrity of three-dimensional spatial data while also providing additional benefits such as simpler equations, worldwide standardization, and the ability to track spatial data accuracy with greater specificity and convenience. This groundbreaking spatial model incorporates both a functional model and a stochastic model to connect the physical world to the ECEF rectangular system. Combining horizontal and vertical data into a single, three-dimensional database, this authoritative monograph provides a logical development of theoretical concepts and practical tools that can be used to handle spatial data mo...

Spatial olfactory learning facilitates long-term depression in the hippocampus.

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André, Marion Agnès Emma; Manahan-Vaughan, Denise

2013-10-01

Recently, it has emerged that visual spatial exploration facilitates synaptic plasticity at different synapses within the trisynaptic network. Particularly striking is the finding that visuospatial contexts facilitate hippocampal long-term depression (LTD), raising the possibility that this form of plasticity may be important for memory formation. It is not known whether other sensory modalities elicit similar permissive effects on LTD. Here, we explored if spatial olfactory learning facilitates LTD in the hippocampus region of freely behaving rats. Patterned afferent stimulation of the Schaffer collaterals elicited short-term depression (STD) (<1 h) of evoked responses in the Stratum radiatum of the CA1 region. Coupling of this protocol with novel exploration of a spatial constellation of olfactory cues facilitated short-term depression into LTD that lasted for over 24 h. Facilitation of LTD did not occur when animals were re-exposed 1 week later to the same odors in the same spatial constellation. Evaluation of learning behavior revealed that 1 week after the 1st odor exposure, the animals remembered the odors and their relative positions. These data support that the hippocampus can use nonvisuospatial resources, and specifically can use spatial olfactory information, to facilitate LTD and to generate spatial representations. The data also support that a tight relationship exists between the processing of spatial contextual information and the expression of LTD in the hippocampus. Copyright © 2013 Wiley Periodicals, Inc.

Spatiality of environmental law

DEFF Research Database (Denmark)

Baaner, Lasse; Hvingel, Line

2015-01-01

, examines legal regulation as spatial information. It aims to deepen the understanding of spatiality as a core element of environmental law, and to connect it to the basic concept of representation used in giscience. It concludes that the future path for e-Government demands a shift in legal paradigm, from...... maps showing representations of applied legal norms, to maps build on datasets that have legal authority. That will integrate legal and geographic information systems, and improve the legal accountability of decision support systems used in e-Government services based on spatio-legal data....

Focusing on Presentation Instead of Representation: Perspectives on Representational and Non-Representational Language-Games for Educational History and Theory

Science.gov (United States)

Fendler, Lynn; Smeyers, Paul

2015-01-01

Debates in science seem to depend on referential language-games, but in other senses they do not. This article addresses non-representational theory. It is a branch of newer approaches to cultural geography that strive to get a handle on spatial relationships not by representing them, but rather by presenting them. In this case, present connotes…

PLCζ Induced Ca2+ Oscillations in Mouse Eggs Involve a Positive Feedback Cycle of Ca2+ Induced InsP3 Formation From Cytoplasmic PIP2

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Sanders, Jessica R.; Ashley, Bethany; Moon, Anna; Woolley, Thomas E.; Swann, Karl

2018-01-01

Egg activation at fertilization in mammalian eggs is caused by a series of transient increases in the cytosolic free Ca2+ concentration, referred to as Ca2+ oscillations. It is widely accepted that these Ca2+ oscillations are initiated by a sperm derived phospholipase C isoform, PLCζ that hydrolyses its substrate PIP2 to produce the Ca2+ releasing messenger InsP3. However, it is not clear whether PLCζ induced InsP3 formation is periodic or monotonic, and whether the PIP2 source for generating InsP3 from PLCζ is in the plasma membrane or the cytoplasm. In this study we have uncaged InsP3 at different points of the Ca2+ oscillation cycle to show that PLCζ causes Ca2+ oscillations by a mechanism which requires Ca2+ induced InsP3 formation. In contrast, incubation in Sr2+ media, which also induces Ca2+ oscillations in mouse eggs, sensitizes InsP3-induced Ca2+ release. We also show that the cytosolic level Ca2+ is a key factor in setting the frequency of Ca2+ oscillations since low concentrations of the Ca2+ pump inhibitor, thapsigargin, accelerates the frequency of PLCζ induced Ca2+ oscillations in eggs, even in Ca2+ free media. Given that Ca2+ induced InsP3 formation causes a rapid wave during each Ca2+ rise, we use a mathematical model to show that InsP3 generation, and hence PLCζ's substate PIP2, has to be finely distributed throughout the egg cytoplasm. Evidence for PIP2 distribution in vesicles throughout the egg cytoplasm is provided with a rhodamine-peptide probe, PBP10. The apparent level of PIP2 in such vesicles could be reduced by incubating eggs in the drug propranolol which also reversibly inhibited PLCζ induced, but not Sr2+ induced, Ca2+ oscillations. These data suggest that the cytosolic Ca2+ level, rather than Ca2+ store content, is a key variable in setting the pace of PLCζ induced Ca2+ oscillations in eggs, and they imply that InsP3 oscillates in synchrony with Ca2+ oscillations. Furthermore, they support the hypothesis that PLCζ and sperm

Complementary theta resonance filtering by two spatially segregated mechanisms in CA1 hippocampal pyramidal neurons.

Science.gov (United States)

Hu, Hua; Vervaeke, Koen; Graham, Lyle J; Storm, Johan F

2009-11-18

Synaptic input to a neuron may undergo various filtering steps, both locally and during transmission to the soma. Using simultaneous whole-cell recordings from soma and apical dendrites from rat CA1 hippocampal pyramidal cells, and biophysically detailed modeling, we found two complementary resonance (bandpass) filters of subthreshold voltage signals. Both filters favor signals in the theta (3-12 Hz) frequency range, but have opposite location, direction, and voltage dependencies: (1) dendritic H-resonance, caused by h/HCN-channels, filters signals propagating from soma to dendrite when the membrane potential is close to rest; and (2) somatic M-resonance, caused by M/Kv7/KCNQ and persistent Na(+) (NaP) channels, filters signals propagating from dendrite to soma when the membrane potential approaches spike threshold. Hippocampal pyramidal cells participate in theta network oscillations during behavior, and we suggest that that these dual, polarized theta resonance mechanisms may convey voltage-dependent tuning of theta-mediated neural coding in the entorhinal/hippocampal system during locomotion, spatial navigation, memory, and sleep.

Ferutinin as a Ca(2+) complexone: lipid bilayers, conductometry, FT-IR, NMR studies and DFT-B3LYP calculations.

Science.gov (United States)

Dubis, A; Zamaraeva, M V; Siergiejczyk, L; Charishnikova, O; Shlyonsky, V

2015-10-07

Calcium ionophoretic properties of ferutinin were re-evaluated in solvent-containing bilayer lipid membranes. The slopes of conductance-concentration curves suggest that in the presence of a solvent in the membrane the majority of complexes appear to consist of a single terpenoid molecule bound to one Ca ion. By contrast, the stoichiometry of ferutinin-Ca(2+) complexes in acetone determined using the conductometric method was 2 : 1. While the cation-cation selectivity of ferutinin did not change, the cation-anion selectivity slightly decreased in solvent containing membranes. FT-IR and NMR data together with DFT calculations at the B3LYP/6-31G(d) level of theory indicate that in the absence of Ca ions ferutinin molecules are hydrogen-bonded at the phenol hydroxyl groups. The variations of absorption assigned to -OH and -C-O stretching mode suggest that ferutinin interacts strongly with Ca ions via the hydroxyl group of ferutinol and carboxyl oxygen of the complex ether bond. The coordination through the carbonyl group of ferutinin was demonstrated by theoretical calculations. Taken together, ferutinin molecules form H-bonded dimers, while complexation of Ca(2+) by ferutinin ruptures this hydrogen bond due to spatial re-orientation of the ferutinin molecules from parallel to antiparallel alignment.

Spatial representation of magnitude in humans (Homo sapiens), Western lowland gorillas (Gorilla gorilla gorilla), and American black bears (Ursus americanus).

Science.gov (United States)

Johnson-Ulrich, Zoe; Vonk, Jennifer

2018-05-04

The spatial-numerical association of response codes (SNARC) effect is the tendency for humans to respond faster to relatively larger numbers on the left or right (or with the left or right hand) and faster to relatively smaller numbers on the other side. This effect seems to occur due to a spatial representation of magnitude either in occurrence with a number line (wherein participants respond to relatively larger numbers faster on the right), other representations such as clock faces (responses are reversed from number lines), or culturally specific reading directions, begging the question as to whether the effect may be limited to humans. Given that a SNARC effect has emerged via a quantity judgement task in Western lowland gorillas and orangutans (Gazes et al., Cog 168:312-319, 2017), we examined patterns of response on a quantity discrimination task in American black bears, Western lowland gorillas, and humans for evidence of a SNARC effect. We found limited evidence for SNARC effect in American black bears and Western lowland gorillas. Furthermore, humans were inconsistent in direction and strength of effects, emphasizing the importance of standardizing methodology and analyses when comparing SNARC effects between species. These data reveal the importance of collecting data with humans in analogous procedures when testing nonhumans for effects assumed to bepresent in humans.

Synthesis and characterization of nano-sized CaCO3 in purified diet

Science.gov (United States)

Mulyaningsih, N. N.; Tresnasari, D. R.; Ramahwati, M. R.; Juwono, A. L.; Soejoko, D. S.; Astuti, D. A.

2017-07-01

The growth and development of animals depend strongly on the balanced nutrition in the diet. This research aims is to characterize the weight variations of nano-sized calcium carbonate (CaCO3) in purified diet that to be fed to animal model of rat. The nano-sized CaCO3 was prepared by milling the calcium carbonate particles for 20 hours at a rotation speed of 1000 rpm and resulting particle size in a range of 2-50 nm. Nano-sized CaCO3 added to purified diet to the four formulas that were identified as normal diet (N), deficiency calcium (DC), rich in calcium (RC), and poor calcium (PC) with containing in nano-sized CaCO3 much as 0.50 %, 0.00 %, 0.75 % and 0.25 % respectively. The nutritional content of the purified diet was proximate analyzed, it resulted as followed moisture, ash, fat, protein, crude fiber. The quantities of chemical element were analyzed by atomic absorption spectrometry (AAS), it resulted iron, magnesium, potassium and calcium. The results showed that N diet (Ca: 16,914.29 ppm) were suggested for healthy rats and RC diet (Ca: 33,696.13 ppm) for conditioned osteoporosis rats. The crystalline phases of the samples that were examined by X-ray diffraction showed that crystalline phase increased with the increasing concentration of CaCO3.

Long-term sustainability of microbial-induced CaCO3 precipitation in aqueous media.

Science.gov (United States)

Gat, Daniella; Ronen, Zeev; Tsesarsky, Michael

2017-10-01

Microbially induced CaCO 3 precipitation (MICP) via urea hydrolysis is an emerging technique for soil amelioration, building materials rehabilitation and pollutants sequestration amongst other various environmental applications. The successful application of MICP requires the sustainability of the precipitated CaCO 3 ; to which the fate of ammonia, the main by-product of ureolysis, is potentially significante. Ammonia volatilization and biological ammonia oxidation both induce a pH decrease, which, in turn, might cause CaCO 3 dissolution. To examine the potential effect of accumulated ammonia on precipitated CaCO 3 , we conducted a long-term MICP batch experiment, using environmental enrichment cultures of ureolytic bacteria. Here we show that CaCO 3 precipitation was completed within 15-27 days, along with a rise in ammonium concentration. Following completion of ureolysis and precipitation, ammonium concentrations decreased, leading to a pH decrease. About 30 days after precipitation was completed, as much as 30% CaCO 3 dissolution, was observed. A two-step model, describing urea hydrolysis followed by the removal of ammonia from the precipitation solution, predicted CaCO 3 dissolution due to ammonia volatilization. We suggest that ureolytic MICP might result in ammonia volatilization, leading to significant CaCO 3 dissolution. These results provide basic insights into the sustainability of ureolytic MICP and should further encourage removal of the accumulated ammonia from the treated site. Copyright © 2017 Elsevier Ltd. All rights reserved.

New link polynomial obtained from octet representation of quantum sl(3) enveloping algebra

International Nuclear Information System (INIS)

Ma Zhongqi.

1989-08-01

The quantum Clebsch-Gordan coefficients for the coproduct 8x8 of the quantum sl(3) enveloping algebra are computed. In the decomposition of the coproduct 8x8, there are two octet representations which are identified by the symmetry in changing the order of the factor octet representations. The corresponding R q matrix, and a new link polynomial are obtained. (author). 14 refs, 3 tabs

Why Do Organisms in the Atlantic Ocean Produce So Much CaCO3?

Science.gov (United States)

Toggweiler, J. R.

2010-12-01

Sediments in the Atlantic are richer in CaCO3 than sediments in the other oceans. Sediment trap observations show that sinking particles in the Atlantic also tend to have more CaCO3 in relation to organic carbon than sinking particles elsewhere. The reason for the extra production of CaCO3 has never been very clear. The Atlantic is unusual because it receives much more than its share of the global input of river water. River water adds alkalinity to the surface ocean while the production of CaCO3 takes it away. In this presentation a new tracer, called Alk*, is derived from the surface alkalinity distribution to highlight the impact of river inputs and the production of CaCO3. If the production of CaCO3 were evenly distributed across the ocean one would expect the Atlantic to have a higher level of Alk* becaused of its river inputs. We find instead that Alk* is lower in the middle of the Atlantic than almost any place else. This, of course, is consistent with the fact that organisms in the Atlantic produce a lot of CaCO3. Comparison with other areas with especially low values of Alk* (Red Sea and northern Arabian Sea) shows that the production of CaCO3 is highly correlated across the ocean with the surface salinity. Hence, we argue that organisms in the Atlantic produce a lot of CaCO3 simply because the Atlantic is so salty. Salty waters, by definition, have more CO3= ions, which increase the supersaturation with respect to calcite and aragonite. This finding, while extremely simple, has major implifications for the impact of ocean acidification on calcifying organisms.

Mice lacking hippocampal left-right asymmetry show non-spatial learning deficits.

Science.gov (United States)

Shimbo, Akihiro; Kosaki, Yutaka; Ito, Isao; Watanabe, Shigeru

2018-01-15

Left-right asymmetry is known to exist at several anatomical levels in the brain and recent studies have provided further evidence to show that it also exists at a molecular level in the hippocampal CA3-CA1 circuit. The distribution of N-methyl-d-aspartate (NMDA) receptor NR2B subunits in the apical and basal synapses of CA1 pyramidal neurons is asymmetrical if the input arrives from the left or right CA3 pyramidal neurons. In the present study, we examined the role of hippocampal asymmetry in cognitive function using β2-microglobulin knock-out (β2m KO) mice, which lack hippocampal asymmetry. We tested β2m KO mice in a series of spatial and non-spatial learning tasks and compared the performances of β2m KO and C57BL6/J wild-type (WT) mice. The β2m KO mice appeared normal in both spatial reference memory and spatial working memory tasks but they took more time than WT mice in learning the two non-spatial learning tasks (i.e., a differential reinforcement of lower rates of behavior (DRL) task and a straight runway task). The β2m KO mice also showed less precision in their response timing in the DRL task and showed weaker spontaneous recovery during extinction in the straight runway task. These results indicate that hippocampal asymmetry is important for certain characteristics of non-spatial learning. Copyright © 2017 Elsevier B.V. All rights reserved.

Ceramic powders of CaZrO3. Preparation and sintering

International Nuclear Information System (INIS)

Tamborenea, S.; Coronel, A.; Mazzoni, A.D.; Aglietti, E.F.

2003-01-01

Calcium zirconate (CaZrO 3 ) is a compound belonging to the perovskite family of the A 2+ B 4+ O 3 6- type with orthorhombic crystalline structure (distorted perovskite).CaZrO 3 is used in the manufacture of sensors of oxygen, humidity, hydrogen and hydrocarbides.Additionally, it is also being studied for the manufacture of thermistors.The calcium zirconate preparation by solid state reaction from stoichiometric mixtures of CaCO 3 and ZrO 2 is studied.The formation reaction was followed by thermal analysis techniques (DTA-TG-DTG) and X-ray diffraction (XRD).The different behaviour of the mixtures was studied according to the milling type employed.It could be observed a shift of some peaks, mainly of TG (gravimetry) with a tendency to a temperature decrease.These changes are mainly influenced by the amorphization effects on the carbonate and by the mixing caused by the milling type used.The powder (CaZrO 3 ) was isostatically pressed obtaining then green densities of 50% of the theoretical one.Sintering was made in air between 1300 and 1600degC at times between 0 and 240.Densities reached were between 90 and 95% increasing with the temperature and the sintering time

EYE TRACKING TO EXPLORE THE IMPACTS OF PHOTOREALISTIC 3D REPRESENTATIONS IN PEDSTRIAN NAVIGATION PERFORMANCE

Directory of Open Access Journals (Sweden)

W. Dong

2016-06-01

Full Text Available Despite the now-ubiquitous two-dimensional (2D maps, photorealistic three-dimensional (3D representations of cities (e.g., Google Earth have gained much attention by scientists and public users as another option. However, there is no consistent evidence on the influences of 3D photorealism on pedestrian navigation. Whether 3D photorealism can communicate cartographic information for navigation with higher effectiveness and efficiency and lower cognitive workload compared to the traditional symbolic 2D maps remains unknown. This study aims to explore whether the photorealistic 3D representation can facilitate processes of map reading and navigation in digital environments using a lab-based eye tracking approach. Here we show the differences of symbolic 2D maps versus photorealistic 3D representations depending on users’ eye-movement and navigation behaviour data. We found that the participants using the 3D representation were less effective, less efficient and were required higher cognitive workload than using the 2D map for map reading. However, participants using the 3D representation performed more efficiently in self-localization and orientation at the complex decision points. The empirical results can be helpful to improve the usability of pedestrian navigation maps in future designs.

Effects of Calcium Source on Biochemical Properties of Microbial CaCO3 Precipitation.

Science.gov (United States)

Xu, Jing; Du, Yali; Jiang, Zhengwu; She, Anming

2015-01-01

The biochemical properties of CaCO3 precipitation induced by Sporosarcina pasteurii, an ureolytic type microorganism, were investigated. Effects of calcium source on the precipitation process were examined, since calcium source plays a key role in microbiologically induced mineralization. Regardless of the calcium source type, three distinct stages in the precipitation process were identified by Ca(2+), NH4 (+), pH and cell density monitoring. Compared with stage 1 and 3, stage 2 was considered as the most critical part since biotic CaCO3 precipitation occurs during this stage. Kinetics studies showed that the microbial CaCO3 precipitation rate for calcium lactate was over twice of that for calcium nitrate, indicating that calcium lactate is more beneficial for the cell activity, which in turn determines urease production and CaCO3 precipitation. X-ray diffraction analysis confirmed the CaCO3 crystal as calcite, although scanning electron microscopy revealed a difference in crystal size and morphology if calcium source was different. The findings of this paper further suggest a promising application of microbiologically induced CaCO3 precipitation in remediation of surface and cracks of porous media, e.g., cement-based composites, particularly by using organic source of calcium lactate.

A novel approach in preparing polymer/nano-CaCO3 composites

Institute of Scientific and Technical Information of China (English)

Zhengying LIU; Runze YU; Mingbo YANG; Jianmin FENG; Wei YANG; Bo YIN

2008-01-01

An novel compounding process using nano-CaCO3 aqueous suspension for preparing polymer/ nano-CaCO3 composites with nanoparticles dispersed at the nanoscale is reported. The process is called the mild mixing method. In this method, the pre-dispersed nano-particle suspensions are blended with melting polymers in a weak shearing field using an extruder, followed by removing the water from the vent. The four typical poly-meric nanocomposites were prepared by mild mixing method. The dispersion of nano-CaCO3 in the matrix of the polymer at the nanoscale was confirmed by scanning electron microscopy (SEM). The molecular weights of polycarbonate (PC) and its nanocomposite showed that the degradation had not occurred during the mild mixing processing. The mechanical properties of the composite with 1.5 wt-% nano-CaCO3 improve slightly. It proved that this approach is suitable for the preparation of nano-composites based on both polar and non-polar polymers.

Investigation of structural and optical properties of CaTiO3 powders doped with Mg2+ and Eu3+ ions

International Nuclear Information System (INIS)

Oliveira, Larissa H.; Savioli, Julia; Moura, Ana P. de; Nogueira, Içamira C.; Li, Maximo S.; Longo, Elson; Varela, José A.; Rosa, Ieda L.V.

2015-01-01

In this work, CaTiO 3 powders doped with Mg 2+ ions and CaTiO 3 powders co-doped with Mg 2+ and Eu 3+ ions were prepared by the polymeric precursor method (PPM). These powders were characterized by different characterization techniques to study the influence of Mg 2+ doping as well as Mg 2+ and Eu 3+ co-doping in structural and optical properties of CaTiO 3 perovskite-type structure. The Rietveld refinement and Micro-Raman analyses suggested the substitution Mg 2+ and Eu 3+ ions in the A-site of CaTiO 3 perovskite. The influence of Mg 2+ doping can be detected by the displacement of calcium and oxygen atomic positions when compared to the non-doped CaTiO 3 powder. When Eu 3+ ions are added to the A-site of this perovskite the excess of positive charge can be compensated by the formation of calcium vacancies. Luminescence data showed that Ca 1-x Mg x TiO 3 and Ca 1x Mg x/2 Eu 2y/3 TiO 3 powders are potential materials for fabrication of lighting devices based on near-UV and blue LED using an excitation wavelength of 397 and/or 450 nm. - Highlights: • CaTiO 3 co-doped with Mg 2+ and Eu 3+ were obtained by the Polymeric Precursor Method. • Incorporation of Mg 2+ and Eu 3+ ions in the CaTiO 3 lattice. • Enhancement of the Eu 3+ photoluminescence

Development of novel antibacterial active, HaCaT biocompatible and biodegradable CA-g-P(3HB-EC biocomposites with caffeic acid as a functional entity

Directory of Open Access Journals (Sweden)

H. M. N. Iqbal

2015-09-01

Full Text Available We have developed novel composites by grafting caffeic acid (CA onto the P(3HB-EC based material and laccase from Trametes versicolor was used for grafting purposes. The resulting composites were designated as CA-g-P(3HB-EC i.e., P(3HB-EC (control, 5CA-g-P(3HB-EC, 10CA-g-P(3HB-EC, 15CA-g-P(3HB-EC and 20CA-g-P(3HB-EC. FT-IR (Fourier-transform infrared spectroscopy was used to examine the functional and elemental groups of the control and laccase-assisted graft composites. Evidently, 15CA-g-P(3HB-EC composite exhibited resilient antibacterial activity against Gram-positive and Gram-negative bacterial strains. Moreover, a significant level of biocompatibility and biodegradability of the CA-g-P(3HB-EC composites was also achieved with the human keratinocytes-like HaCaT cells and soil burial evaluation, respectively. In conclusion, the newly developed novel composites with multi characteristics could well represent the new wave of biomaterials for medical applications, and more specifically have promising future in the infection free would dressings, burn and/or skin regeneration field due to their sophisticated characteristics.

Thermodynamic, electronic, and magnetic properties of intrinsic vacancy defects in antiperovskite Ca3SnO

Science.gov (United States)

Batool, Javaria; Alay-e-Abbas, Syed Muhammad; Amin, Nasir

2018-04-01

The density functional theory based total energy calculations are performed to examine the effect of charge neutral and fully charged intrinsic vacancy defects on the thermodynamic, electronic, and magnetic properties of Ca3SnO antiperovskite. The chemical stability of Ca3SnO is evaluated with respect to binary compounds CaO, CaSn, and Ca2Sn, and the limits of atomic chemical potentials of Ca, Sn, and O atoms for stable synthesis of Ca3SnO are determined within the generalized gradient approximation parametrization scheme. The electronic properties of the pristine and the non-stoichiometric forms of this compound have been explored and the influence of isolated intrinsic vacancy defects (Ca, Sn, and O) on the structural, bonding, and electronic properties of non-stoichiometric Ca3SnO are analyzed. We also predict the possibility of achieving stable ferromagnetism in non-stoichiometric Ca3SnO by means of charge neutral tin vacancies. From the calculated total energies and the valid ranges of atomic chemical potentials, the formation energetics of intrinsic vacancy defects in Ca3SnO are evaluated for various growth conditions. Our results indicate that the fully charged calcium vacancies are thermodynamically stable under the permissible Sn-rich condition of stable synthesis of Ca3SnO, while tin and oxygen vacancies are found to be stable under the extreme Ca-rich condition.

Luminescence properties of undoped CsCaCl3 and CsSrCl3 crystalline scintillators

International Nuclear Information System (INIS)

Fujimoto, Yutaka; Saeki, Keiichiro; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki

2015-01-01

Intrinsic luminescence properties of undoped CsCaCl 3 and CsSrCl 3 crystalline scintillators were studied. The crystal samples were grown by a vertical Bridgman method. Photoluminescence spectra of the crystals showed Auger-free luminescence (AFL) at 310 nm and self-trapped emission (STE) at 400 nm for CsCaCl 3 and 465 nm for CsSrCl 3 , when vacuum ultraviolet (VUV) light at 84 nm and 160 nm excited the crystals. X-ray excited radioluminescence spectra of the crystals showed some emission bands in the 280-600 nm wavelength range, which are owing to AFL, STE, and other origins such as lattice defects and impurities. Scintillation light yield was 400-300 ph/MeV, and the principal scintillation decay time about 2.5 ns and 12 ns for CsCaCl 3 and 1.8 ns and 13 ns for CsSrCl 3 . (author)

RAMONA-3B/MINET composite representation of BWR thermal-hydraulic systems

International Nuclear Information System (INIS)

Van Tuyle, G.J.; Slovik, G.; Cazzoli, E.G.; Nepsee, T.C.; Guppy, J.G.

1985-01-01

The modification and interfacing of two computer codes, RAMONA-3B and MINET, for the thermal hydraulic transient analysis of a Boiling Water Reactor nuclear steam supply system, is described. The RAMONA-3B code provides for multi-channel thermal hydraulics and three-dimensional (or one-dimensional) neutron kinetics analysis of a boiling water reactor core. The RAMONA-3B system representation terminates at the end of the steam line and at the junction of the feedwater line at the vessel inlet. By interfacing RAMONA-3B with MINET, a generic balance-of-plant systems analysis code, a complete BWR systems code with detailed core modeling was obtained. The result is a code of particular importance to the analysis of transients such as ATWS. A comparison between the 3-D and 1-D neutronics representation is provided, along with a test case utilizing the composite RAMONA-3B/MINET code

Perovskite-related Ca(Nb,Ti)O3.33

International Nuclear Information System (INIS)

Guevarra, J.; Smaalen, S. van; Daniels, P.; Rotiroti, N.; Lichtenberg, F.

2005-01-01

Crystals of nominal composition Ca(Nb 0.8 Ti 0.2 )O 3.4 , an n = 5 member of the homologous series A n B n O 3n+2 , have been synthesized by floating-zone melting. The material was found to be multiphase consisting also of the n = 6 type. A good single crystal of this n = 6 type was found and the crystal structure at room temperature was determined by X-ray diffraction using synchrotron radiation. Structure refinements indicate a composition of Ca(Nb 0.76 Ti 0.24 )O 3.33 . The crystal structure is monoclinic P2 1 and consists of slabs of corner-sharing (Nb,Ti)O 6 octahedra interrupted by layers of oxygen atoms. Ca atoms within the slabs are 12-fold coordinated whereas those at the borders show irregular coordination geometries. The octahedral distortion is greatest near the borders of the slabs and least near the middle of the slabs. Ti 4+ preferentially occupy octahedral sites in the middle of slabs. The non-stoichiometry in the refined composition and the insulating character of the material may be explained in terms of extra oxygen, vacancies on the cation sites, or by localization of the electrons in the 4d orbitals of Nb at the borders of slabs. (orig.)

Mg and Ca isotope fractionation during CaCO3 biomineralisation

International Nuclear Information System (INIS)

Chang, Veronica T.-C.; Williams, R.J.P.; Makishima, Akio; Belshawl, Nick S.; O'Nions, R. Keith

2004-01-01

The natural variation of Mg and Ca stable isotopes of carbonates has been determined in carbonate skeletons of perforate foraminifera and reef coral together with Mg/Ca ratios to assess the influence of biomineralisation processes. The results for coral aragonite suggest its formation, in terms of stable isotope behaviour, approximates to inorganic precipitation from a seawater reservoir. In contrast, results for foraminifera calcite suggest a marked biological control on Mg isotope ratios presumably related to its low Mg content compared with seawater. The bearing of these observations on the use of Mg and Ca isotopes as proxies in paleoceanography is considered

Search for the 3-phonon state of 40Ca

International Nuclear Information System (INIS)

Fallot, M.

2002-09-01

We study collective vibrational states of the nucleus: giant resonances and multiphonon states. It has been shown that multiphonon states, which are built with several superimposed giant resonances, can be excited in inelastic heavy ion scattering near the grazing angle. No three photon states have been observed until now. An experiment has been performed at GANIL, aiming at the observation of the 3-phonon state built with the giant quadrupole resonance (GQR) in 40 Ca, with the reaction 40 Ca + 40 Ca at 50 A.Me.V. The ejectile was identified in the SPEG spectrometer. Light charged particles were detected in 240 CsI scintillators of the INDRA 4π array. The analysis confirms the previous results about the GQR and the 2-phonon state in 40 Ca. For the first time, we have measured an important direct decay branch of the GQR by alpha particles. Applying the so-called 'missing energy method' to events containing three protons measured in coincidence with the ejectile, we observe a direct decay branch revealing the presence of a 3-phonon state in the excitation energy region expected for the triple GQR. Dynamical processes are also studied in the inelastic channel, emphasizing a recently discovered mechanism named towing-mode. We observe for the first time the towing-mode of alpha particles. The energies of multiphonon states in 40 Ca and 208 Pb have been computed microscopically including some anharmonicities via boson mapping methods. The basis of the calculation has been extended to the 3-phonon states. Our results show large anharmonicities (several MeV), due to the coupling of 3-phonon states to 2-phonon states. The extension of the basis to 4-phonon states has been performed for the first time. The inclusion of the 4 phonon states in the calculation did not affect the previous observations concerning the 2-phonon states. Preliminary results on the anharmonicities of the 3-phonon states are presented. (author)

CaCO{sub 3} scaling in pressure retarded osmosis

Energy Technology Data Exchange (ETDEWEB)

Thelin, Willy; Holt, Torleif; Sivertsen, Edvard

2010-07-01

Full text: Osmotic power is a renewable energy source exploiting the energy of mixing between freshwater and seawater. Pressure retarded osmosis (PRO) is one of the methods that is technically feasible to extract this energy. In PRO, freshwater and seawater are separated by a semi permeable membrane that ideally only will allow transport of water, whereas salts and dissolved constituents will be retained by the membrane. Due to the difference in osmotic pressure across the membrane, there will be an osmotic transport of water from the freshwater side to the seawater side of the membrane. The osmotic transport of water will take place against a pressure gradient equal to approximately half the osmotic pressure between the two solutions. The resulting net volume increase on the seawater side will be utilised to drive a turbine. One of the major challenges towards realisation of osmotic power as a commercially feasible renewable energy source will be to maintain stable performance of the PRO membranes over time. In this respect the control of membrane fouling and scaling will be essential. Both adequate pre-treatment, in order to reduce the fouling potential of incoming feed waters, and operation and maintenance aspects such as flux control, disinfection and suitable membrane cleaning procedures will be important. A study investigating the CaCO{sub 3} scaling potential in PRO has been accomplished. Laboratory experiments with model solutions having different saturation index (SI) with respect to CaCO{sub 3} have been performed, and the flux decline over time due to precipitation of CaCO{sub 3} scale was monitored. A transport model estimating the concentration of Ca{sup 2+} and CO{sub 3}{sup 2-} at the membrane surface was developed and used to determine the SI for each of the experiments. Further, the SI of CaCO{sub 3} for a selection of 32 Norwegian rivers were calculated and for all cases the SI at the membrane surface was simulated for operation in PRO. (Author)

Vacancy induced metallicity at the CaHfO3/SrTiO3 interface

KAUST Repository

Nazir, Safdar

2011-03-31

Density functional theory is used to study the electronic properties of the oxide heterointerfaceCaHfO3/SrTiO3. Structural relaxation is carried out with and without O vacancies. As compared to related interfaces, strongly reduced octahedral distortions are found. Stoichiometric interfaces between the wide band gap insulatorsCaHfO3 and SrTiO3 turn out to exhibit an insulating state. However, interface metallicity is introduced by O vacancies, in agreement with experiment. The reduced octahedral distortions and necessity of O deficiency indicate a less complicated mechanism for the creation of the interfacial electron gas.

Vacancy induced metallicity at the CaHfO3/SrTiO3 interface

KAUST Repository

Nazir, Safdar; Pulikkotil, J. J.; Schwingenschlö gl, Udo; Singh, Nirpendra

2011-01-01

Density functional theory is used to study the electronic properties of the oxide heterointerfaceCaHfO3/SrTiO3. Structural relaxation is carried out with and without O vacancies. As compared to related interfaces, strongly reduced octahedral distortions are found. Stoichiometric interfaces between the wide band gap insulatorsCaHfO3 and SrTiO3 turn out to exhibit an insulating state. However, interface metallicity is introduced by O vacancies, in agreement with experiment. The reduced octahedral distortions and necessity of O deficiency indicate a less complicated mechanism for the creation of the interfacial electron gas.

In situ biosynthesis of bacterial nanocellulose-CaCO3 hybrid bionanocomposite: One-step process

International Nuclear Information System (INIS)

Mohammadkazemi, Faranak; Faria, Marisa; Cordeiro, Nereida

2016-01-01

In this work, a simple and green route to the synthesis of the bacterial nanocellulose-calcium carbonate (BNC/CaCO 3 ) hybrid bionanocomposites using one-step in situ biosynthesis was studied. The CaCO 3 was incorporated in the bacterial nanocellulose structure during the cellulose biosynthesis by Gluconacetobacter xylinus PTCC 1734 bacteria. Hestrin-Schramm (HS) and Zhou (Z) culture media were used to the hybrid bionanocomposites production and the effect of ethanol addition was investigated. Attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, inverse gas chromatography and thermogravimetric analysis were used to characterize the samples. The experimental results demonstrated that the ethanol and culture medium play an important role in the BNC/CaCO 3 hybrid bionanocomposites production, structure and properties. The BNC/CaCO 3 biosynthesized in Z culture medium revealed higher O/C ratio and amphoteric surface character, which justify the highest CaCO 3 content incorporation. The CaCO 3 was incorporated into the cellulosic matrix decreasing the bacterial nanocellulose crystallinity. This work reveals the high potential of in situ biosynthesis of BNC/CaCO 3 hybrid bionanocomposites and opens a new way to the high value-added applications of bacterial nanocellulose. - Graphical Abstract: Display Omitted - Highlights: • BNC/CaCO 3 hybrid bionanocomposites were produced using in situ biosynthesis process. • Ethanol and culture medium play an important role in the production and properties. • Z-BNC/CaCO 3 bionanocomposites revealed higher O/C ratio and amphoteric surface character. • CaCO 3 incorporated into the BNC decreased crystallinity.